**Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence**

Janet Flores-Lujano, Juan Carlos Núñez-Enríquez, Angélica Rangel-López, David Aldebarán-Duarte, Arturo Fajardo-Gutiérrez and Juan Manuel Mejía-Aranguré

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/52717

**1. Introduction**

[113] Kwan, M. L, Jensen, C. D, Block, G, Hudes, M. L, Chu, L. W, & Buffler, P. A. Public

[114] Sam, T. N, Kersey, J. H, Linabery, A. M, Johnson, K. J, Heerema, N. A, Hilden, J. M, Davies, S. M, Reaman, G. H, & Ross, J. A. MLL gene rearrangements in infant leukemia vary with age at diagnosis and selected demographic factors: a Children's Oncology

Group (COG) study. Pediatric blood & cancer (2012). , 58(6), 836-839.

health reports (2009). , 124(4), 503-514.

170 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

The role of infection in the etiology of leukemia was revealed for the first time more than ninety years ago through a series of cases reported by Gordon Ward in the year 1917. These cases included 1457 children with acute leukemia, but the results were inconclusive. Later, in another study by Poynton, Thursfield and Paterson, the authors reported that it was not possible to attribute the etiology of leukemia to a single infectious agent and emphasized the importance of host susceptibility in the acquirement of an infection and the development of acute leukemia.[1,2]

In 1937, in a study conducted in England by Kellet, it was mentioned that an infection could be the causative agent for acute leukemia when the infection is widely distributed but has low infectivity. This conclusion was supported by Cooke in 1942 in a study involving 33 pe‐ diatric care units in the United States, who found that the peak age of 2 to 5 years in children with acute leukemia correlated with the peak of increased incidence of diseases, such as measles and diphtheria. [3,4]

One of the most important scientific contributions in this regard was made by Kinlen et al., who found a relationship between high incidence rates of acute leukemia and Non-Hodgkin's lymphoma and infections in children living near rural areas. Kinlen's findings resulted in the emergence of a hypothesis proposing that leukemia could be caused by exposure to an infec‐ tious agent in a susceptible population and, in this case, a mixed population (rural-urban), causing an abnormal immune response that increases the risk of developing the disease. [5,7]

© 2013 Flores-Lujano et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Moreover, Greaves et al. provided a new approach to the hypothesis that had been raised by Kellet, now basing it on biological and epidemiological data on acute leukemia. These au‐ thors suggested the hypothesis of late infection, which is explained by two stages: the first stage occurs with a mutation in utero at the same time that precursor B cells are developing and a second stage, during the postnatal period, in which the cell that undergoes a mutation is exposed to a common infection late in the first year of the child's life. [8-13]

ther adjusted for the child's age being <4 years at diagnosis, the OR was 1.78 (95% CI: 1.04-3.04). Furthermore, in 2010, these results were supported by the German study of Kaatsch et al., who reported an OR of 1.47 (95% CI: 1.06-2.04). [33,35] These findings, however, are inconsistent

Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence

http://dx.doi.org/10.5772/52717

173

While there are maternal protective barriers during pregnancy that help to prevent infec‐ tions that may occur in the child at some point after birth, when these barriers cease to exist and the immune system is not well developed, the child is at greater risk for developing in‐ fections. Therefore, many epidemiological studies have considered the neonatal period to be a crucial step in the assessment of the relationship between infections and the development of acute leukemia. In 1999, McKinney et al. reported that the presence of neonatal infection was associated with a decreased risk of acute lymphoblastic leukemia (ALL) in Scottish chil‐ dren, with an OR of 0.49 (95% CI: 0.26 to 0.95) being more evident in cases of skin infections, such as omphalitis and/or infection in the skin around the umbilical cord, with an OR of 0.20 (95% CI: 0.05 to 0.87) for all leukemias and for acute lymphoblastic leukemia, regardless of

Breast milk is considered to be the first vaccine that a child receives during the first months of life, and it protects against infections by stimulating the immune system. There are many mechanisms by which breast milk exerts its antimicrobial and immunological properties. Among the most important mechanisms are the immunoglobulins, interleukins, lactoferrin, mucin, various types of enzymes (e.g., lysozyme and lipases), opsonins, cytokines, prosta‐ glandins and other small peptides. Also involved in these functions are T and B lympho‐ cytes, which are present in breast milk. Thus, the study of breastfeeding as a protective factor against infections during the first year of life has generated scientific interest. [47-50] In most epidemiological studies, it has been documented that breastfeeding favorably influ‐ ences both the response to infection and the modulation of the child's immune system.

These factors require further investigation, as there is inconsistency among the epidemiolog‐ ical studies conducted thus far regarding whether a child's immune system will respond ap‐ propriately to an infectious agent after the child has been breastfed for the first six months of life. However, if the child has had recurrent common infections, his/her immune system will

The child's attendance at daycare also represents a quantifiable index of infection during the first year of life in relation to the development of leukemia. For its implementation in epide‐ miological studies, investigators have used the age of entry to kindergarten, the hours spent in child care, the number of partners in the nursery, the presence of infection during their stay in

with those reported by other authors. [36-45]

birth type (vaginal or by cesarean section). [46]

have an adequate response to a delayed infection.

**2.3. Neonatal infections**

**2.4. Breastfeeding**

[21,33,51-64]

**2.5. Attendance at daycare**

## **2. Measuring exposure to infection with proxy variables**

Over time, in epidemiological studies that have attempted to determine whether an associa‐ tion between early infections and the development of leukemia exists, some indicators have been used to quantify the exposure to infection. These indicators are designated as "proxies" and include socioeconomic status, surgical history, allergic diseases, immunizations, attend‐ ance at daycare, breastfeeding, neonatal infections, and prenatal history, among others. [14-25]

#### **2.1. Socioeconomic status**

In several epidemiological studies that have assessed infections during the first year of life in children, it was considered to be important to adjust for socioeconomic status because a high socioeconomic status is consistently associated with the development of leukemia and protection against infection. On the contrary, those who have a low socioeconomic status are at a higher risk for the presence of common infections. [26-30] It is important to note, howev‐ er, that the methods used to measure this variable are not consistent. For example, Steensel-Moll et al. measured socioeconomic status in The Netherlands (1973-1980) according to the parents' education, while other authors have used, for example, the number of people per room, home ownership, and family income as indicators of socioeconomic status. [15-17,21,22,31-33]

#### **2.2. Prenatal history**

The study of prenatal history is interesting as a proxy because it assesses the association be‐ tween infections and the development of leukemia before birth in an indirect manner, taking into account the fact that, being part of a binomial mother-fetus, the child may have been ex‐ posed to infection during the intrauterine period if the mother had an infection during preg‐ nancy. For example, in a study by Fedrick and Alberman in 1972, a positive association was reported between influenza during pregnancy and the development of leukemia and lympho‐ ma, where a RR of 9 (p <0.001) was obtained. Other studies have used other variables associat‐ ed with pregnancy for the same purpose. For example, whether antimicrobials and/or antiviral drugs were used if the mother had infections was considered. [34] Moreover, the authors of several studies considered a history of antibiotic and/or antiviral use by mothers during preg‐ nancy to reflect the fact that they had been exposed to an infectious process. In this regard, In‐ fante-Rivard et al. noted during 1989 to 1995 that the use of antimicrobials during pregnancy increased the risk of leukemia, with an OR of 1.5 (95% CI:1.02-2.21). When the data were fur‐ ther adjusted for the child's age being <4 years at diagnosis, the OR was 1.78 (95% CI: 1.04-3.04). Furthermore, in 2010, these results were supported by the German study of Kaatsch et al., who reported an OR of 1.47 (95% CI: 1.06-2.04). [33,35] These findings, however, are inconsistent with those reported by other authors. [36-45]

#### **2.3. Neonatal infections**

Moreover, Greaves et al. provided a new approach to the hypothesis that had been raised by Kellet, now basing it on biological and epidemiological data on acute leukemia. These au‐ thors suggested the hypothesis of late infection, which is explained by two stages: the first stage occurs with a mutation in utero at the same time that precursor B cells are developing and a second stage, during the postnatal period, in which the cell that undergoes a mutation

Over time, in epidemiological studies that have attempted to determine whether an associa‐ tion between early infections and the development of leukemia exists, some indicators have been used to quantify the exposure to infection. These indicators are designated as "proxies" and include socioeconomic status, surgical history, allergic diseases, immunizations, attend‐ ance at daycare, breastfeeding, neonatal infections, and prenatal history, among others. [14-25]

In several epidemiological studies that have assessed infections during the first year of life in children, it was considered to be important to adjust for socioeconomic status because a high socioeconomic status is consistently associated with the development of leukemia and protection against infection. On the contrary, those who have a low socioeconomic status are at a higher risk for the presence of common infections. [26-30] It is important to note, howev‐ er, that the methods used to measure this variable are not consistent. For example, Steensel-Moll et al. measured socioeconomic status in The Netherlands (1973-1980) according to the parents' education, while other authors have used, for example, the number of people per room, home ownership, and family income as indicators of socioeconomic status.

The study of prenatal history is interesting as a proxy because it assesses the association be‐ tween infections and the development of leukemia before birth in an indirect manner, taking into account the fact that, being part of a binomial mother-fetus, the child may have been ex‐ posed to infection during the intrauterine period if the mother had an infection during preg‐ nancy. For example, in a study by Fedrick and Alberman in 1972, a positive association was reported between influenza during pregnancy and the development of leukemia and lympho‐ ma, where a RR of 9 (p <0.001) was obtained. Other studies have used other variables associat‐ ed with pregnancy for the same purpose. For example, whether antimicrobials and/or antiviral drugs were used if the mother had infections was considered. [34] Moreover, the authors of several studies considered a history of antibiotic and/or antiviral use by mothers during preg‐ nancy to reflect the fact that they had been exposed to an infectious process. In this regard, In‐ fante-Rivard et al. noted during 1989 to 1995 that the use of antimicrobials during pregnancy increased the risk of leukemia, with an OR of 1.5 (95% CI:1.02-2.21). When the data were fur‐

is exposed to a common infection late in the first year of the child's life. [8-13]

**2. Measuring exposure to infection with proxy variables**

172 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

**2.1. Socioeconomic status**

[15-17,21,22,31-33]

**2.2. Prenatal history**

While there are maternal protective barriers during pregnancy that help to prevent infec‐ tions that may occur in the child at some point after birth, when these barriers cease to exist and the immune system is not well developed, the child is at greater risk for developing in‐ fections. Therefore, many epidemiological studies have considered the neonatal period to be a crucial step in the assessment of the relationship between infections and the development of acute leukemia. In 1999, McKinney et al. reported that the presence of neonatal infection was associated with a decreased risk of acute lymphoblastic leukemia (ALL) in Scottish chil‐ dren, with an OR of 0.49 (95% CI: 0.26 to 0.95) being more evident in cases of skin infections, such as omphalitis and/or infection in the skin around the umbilical cord, with an OR of 0.20 (95% CI: 0.05 to 0.87) for all leukemias and for acute lymphoblastic leukemia, regardless of birth type (vaginal or by cesarean section). [46]

#### **2.4. Breastfeeding**

Breast milk is considered to be the first vaccine that a child receives during the first months of life, and it protects against infections by stimulating the immune system. There are many mechanisms by which breast milk exerts its antimicrobial and immunological properties. Among the most important mechanisms are the immunoglobulins, interleukins, lactoferrin, mucin, various types of enzymes (e.g., lysozyme and lipases), opsonins, cytokines, prosta‐ glandins and other small peptides. Also involved in these functions are T and B lympho‐ cytes, which are present in breast milk. Thus, the study of breastfeeding as a protective factor against infections during the first year of life has generated scientific interest. [47-50] In most epidemiological studies, it has been documented that breastfeeding favorably influ‐ ences both the response to infection and the modulation of the child's immune system. [21,33,51-64]

These factors require further investigation, as there is inconsistency among the epidemiolog‐ ical studies conducted thus far regarding whether a child's immune system will respond ap‐ propriately to an infectious agent after the child has been breastfed for the first six months of life. However, if the child has had recurrent common infections, his/her immune system will have an adequate response to a delayed infection.

#### **2.5. Attendance at daycare**

The child's attendance at daycare also represents a quantifiable index of infection during the first year of life in relation to the development of leukemia. For its implementation in epide‐ miological studies, investigators have used the age of entry to kindergarten, the hours spent in child care, the number of partners in the nursery, the presence of infection during their stay in the nursery, the social activities being undertaken by the child during the first year, the type of staff who attended to the child during their stay and the hours they remained at home, among others. There is evidence reported by some studies that there is a dose-response effect with re‐ spect to the number of hours that a child remains in a nursery and a lower risk of developing leukemia, and the more a child is in contact with other children, the risk is increased for com‐ mon and recurring infections, thus favoring a better stimulation and maturation of the im‐ mune system. [17,65] In the UK, Gilham et al. also found child attendance at day care during the first year of life to have a protective effect, reporting an OR = 0.69 (95% CI: 0.51 to 0.93, p = 0.02), but this effect was more significant when the child attended during the first 3 months of age, with an OR = 0.52 (95% CI: 0.32 to 0.83, p = 0.007). [66]

of large numbers of immune cells and the increased likelihood of genetic errors caused by pro-oncogenic mutations, which could not be repaired in subsequent divisions. [77-78]

Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence

http://dx.doi.org/10.5772/52717

175

Linabery et al. conducted a meta-analysis to investigate the relationship between allergic diseases and the development of acute leukemia. Three studies reported a positive associa‐ tion in this regard, with an OR of 1.42 (95% CI: 0.60-3.35). Six studies examined whether there was an association between acute lymphoblastic leukemia (ALL) (OR = 0.69; 95% CI: 0.54 to 0.89) and acute myeloid leukemia (AML) (OR = 0.87; 95% CI: 0.62-1.22), but there was heterogeneity among the results. We also performed such a study in asthmatics, and inverse associations were observed between asthma (OR = 0.79; 95% CI: 0.61-1.02), eczema (OR = 0.74; 95% CI: 0.58-0.96) and hay fever (OR = 0.55, 95% CI: 0.46-0.66) and the development of

The individual susceptibility of children who suffer from common diseases and recurrences has been considered to be the main factor leading to surgical interventions that are per‐ formed as part of the treatment of these infections. Some examples of these treatments are adenoidectomy, tonsillectomy, interventions for ear surgery, and appendectomy. It is worth noting that these anatomical structures are important parts of the lymphatic tissue and im‐ mune system, especially during the first two years of life. Thus, their removal would result in immune dysfunction and an increased risk of infections that occur especially during the first year of life, and this mechanism could be involved in the development of acute leuke‐ mia during that time. It is for this reason that epidemiological studies that examine infec‐ tions as an exposure factor in the development of leukemia are controlled by this variable, but there is no epidemiological evidence that surgical interventions studied as a proxy are

Some types of infections that have been evaluated in most epidemiological studies are respi‐ ratory tract infections, gastroenteritis, and those caused by specific infectious agents, such as streptococcus and influenza virus. Other diseases that have been considered are exanthema‐ tous diseases, allergic diseases (e.g., asthma, acute rhinitis, and atopic dermatitis) and gas‐ trointestinal diseases because these diseases are recurrent during the first year of life. This recurrence would result in the child's immune system performing better when mature, de‐ creasing the risk of aberrant responses to infections that could result in the development of acute leukemia. [80,81] This finding was consistent with that of Perillat et al., who conduct‐ ed a study in France in a sample of 280 children with acute leukemia (cases) and 288 healthy children (controls). The authors reported that if the child suffered from recurrent infections before 2 years of age, he/she would be protected from the development of acute leukemia, with an OR = 0.6 (95% CI: 0.4-1.0). These results were statistically significant and consistent

associated with the development of childhood acute leukemia. [68]

ALL. [79]

**2.8. Surgical history**

**3. Epidemiological studies**

with those reported by Neglia et al. [21,22,32,68]

#### **2.6. Immunizations**

Knowing the vaccination history of children is another important approach to understand‐ ing the role of infections in the modern-day development of childhood acute leukemia. This is based on the assumption that vaccines are infectious antigenic stimuli that enable the for‐ mation of antibodies and, therefore, a better performance of the immune system. Vaccines could also be the mechanism by which the development of acute leukemia is prevented. [67] Meanwhile, Schüz et al. conducted a study in Germany (1999) and reported that, in children older than 4 years of age, there was an increased risk of developing leukemia in those with a history of fewer than three vaccines, with an OR of 1.8 (95% CI: 1.2-2.7), and a low risk in children with a history of 4-6 shots, with an OR of 1.3 (95% CI:1.0-1.7), which supports the following dose-response relationship: as the number of vaccines given to children increases, the risk of developing acute leukemia decreases. [68] The role of immunization is still con‐ troversial, however, because, as mentioned above, while some authors conclude that immu‐ nizations provide protection, others have reported the opposite result. [67,69-74]

#### **2.7. Allergic diseases**

The role of allergic diseases (e.g., rhinitis, atopic dermatitis, asthma, and urticaria) as a pro‐ tective factor for the development of leukemia has been controversial in epidemiological re‐ ports. Two hypotheses have been proposed to explain the causal relationship between allergic diseases and cancer, including acute leukemia.

The first hypothesis that we will mention is that of "immune surveillance", which postulates that the immune system can recognize the antigens of malignant cells as foreign and re‐ spond to remove them from the body, preventing the potential development of cancer in most cases. Therefore, it is believed that the presence of an allergic disease would increase the surveillance, providing better control and identifying and eliminating any malignant cells, resulting in an increased incidence of malignancy in people who are immunocompro‐ mised compared with those with an intact immune system. [75,76]

The second hypothesis refers to a "chronic stimulation of the immune system" that would be conferred by allergens that trigger the carcinogenic potential through both the proliferation of large numbers of immune cells and the increased likelihood of genetic errors caused by pro-oncogenic mutations, which could not be repaired in subsequent divisions. [77-78]

Linabery et al. conducted a meta-analysis to investigate the relationship between allergic diseases and the development of acute leukemia. Three studies reported a positive associa‐ tion in this regard, with an OR of 1.42 (95% CI: 0.60-3.35). Six studies examined whether there was an association between acute lymphoblastic leukemia (ALL) (OR = 0.69; 95% CI: 0.54 to 0.89) and acute myeloid leukemia (AML) (OR = 0.87; 95% CI: 0.62-1.22), but there was heterogeneity among the results. We also performed such a study in asthmatics, and inverse associations were observed between asthma (OR = 0.79; 95% CI: 0.61-1.02), eczema (OR = 0.74; 95% CI: 0.58-0.96) and hay fever (OR = 0.55, 95% CI: 0.46-0.66) and the development of ALL. [79]

#### **2.8. Surgical history**

the nursery, the social activities being undertaken by the child during the first year, the type of staff who attended to the child during their stay and the hours they remained at home, among others. There is evidence reported by some studies that there is a dose-response effect with re‐ spect to the number of hours that a child remains in a nursery and a lower risk of developing leukemia, and the more a child is in contact with other children, the risk is increased for com‐ mon and recurring infections, thus favoring a better stimulation and maturation of the im‐ mune system. [17,65] In the UK, Gilham et al. also found child attendance at day care during the first year of life to have a protective effect, reporting an OR = 0.69 (95% CI: 0.51 to 0.93, p = 0.02), but this effect was more significant when the child attended during the first 3 months of

Knowing the vaccination history of children is another important approach to understand‐ ing the role of infections in the modern-day development of childhood acute leukemia. This is based on the assumption that vaccines are infectious antigenic stimuli that enable the for‐ mation of antibodies and, therefore, a better performance of the immune system. Vaccines could also be the mechanism by which the development of acute leukemia is prevented. [67] Meanwhile, Schüz et al. conducted a study in Germany (1999) and reported that, in children older than 4 years of age, there was an increased risk of developing leukemia in those with a history of fewer than three vaccines, with an OR of 1.8 (95% CI: 1.2-2.7), and a low risk in children with a history of 4-6 shots, with an OR of 1.3 (95% CI:1.0-1.7), which supports the following dose-response relationship: as the number of vaccines given to children increases, the risk of developing acute leukemia decreases. [68] The role of immunization is still con‐ troversial, however, because, as mentioned above, while some authors conclude that immu‐

nizations provide protection, others have reported the opposite result. [67,69-74]

The role of allergic diseases (e.g., rhinitis, atopic dermatitis, asthma, and urticaria) as a pro‐ tective factor for the development of leukemia has been controversial in epidemiological re‐ ports. Two hypotheses have been proposed to explain the causal relationship between

The first hypothesis that we will mention is that of "immune surveillance", which postulates that the immune system can recognize the antigens of malignant cells as foreign and re‐ spond to remove them from the body, preventing the potential development of cancer in most cases. Therefore, it is believed that the presence of an allergic disease would increase the surveillance, providing better control and identifying and eliminating any malignant cells, resulting in an increased incidence of malignancy in people who are immunocompro‐

The second hypothesis refers to a "chronic stimulation of the immune system" that would be conferred by allergens that trigger the carcinogenic potential through both the proliferation

age, with an OR = 0.52 (95% CI: 0.32 to 0.83, p = 0.007). [66]

174 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

allergic diseases and cancer, including acute leukemia.

mised compared with those with an intact immune system. [75,76]

**2.6. Immunizations**

**2.7. Allergic diseases**

The individual susceptibility of children who suffer from common diseases and recurrences has been considered to be the main factor leading to surgical interventions that are per‐ formed as part of the treatment of these infections. Some examples of these treatments are adenoidectomy, tonsillectomy, interventions for ear surgery, and appendectomy. It is worth noting that these anatomical structures are important parts of the lymphatic tissue and im‐ mune system, especially during the first two years of life. Thus, their removal would result in immune dysfunction and an increased risk of infections that occur especially during the first year of life, and this mechanism could be involved in the development of acute leuke‐ mia during that time. It is for this reason that epidemiological studies that examine infec‐ tions as an exposure factor in the development of leukemia are controlled by this variable, but there is no epidemiological evidence that surgical interventions studied as a proxy are associated with the development of childhood acute leukemia. [68]

## **3. Epidemiological studies**

Some types of infections that have been evaluated in most epidemiological studies are respi‐ ratory tract infections, gastroenteritis, and those caused by specific infectious agents, such as streptococcus and influenza virus. Other diseases that have been considered are exanthema‐ tous diseases, allergic diseases (e.g., asthma, acute rhinitis, and atopic dermatitis) and gas‐ trointestinal diseases because these diseases are recurrent during the first year of life. This recurrence would result in the child's immune system performing better when mature, de‐ creasing the risk of aberrant responses to infections that could result in the development of acute leukemia. [80,81] This finding was consistent with that of Perillat et al., who conduct‐ ed a study in France in a sample of 280 children with acute leukemia (cases) and 288 healthy children (controls). The authors reported that if the child suffered from recurrent infections before 2 years of age, he/she would be protected from the development of acute leukemia, with an OR = 0.6 (95% CI: 0.4-1.0). These results were statistically significant and consistent with those reported by Neglia et al. [21,22,32,68]

However, Schüz et al. (1999) conducted a case-control study in Germany during 1992-1997. They studied 1184 families of children with acute leukemia (cases) and 2588 families of healthy children (controls) and found no association between common infections and an in‐ creased incidence of leukemia. It is notable, however, that they reported that when the chil‐ dren had a history of surgical procedures, such as appendectomy/tonsillectomy, at least once in their life, their risk of developing acute leukemia increased, with an OR of 1.4 (95% CI: 1.0-1.9). These authors also observed a significant association with pneumonia, with an OR of 1.7 (95% CI: 1.2-2.3), whereas bronchitis was not associated with the development of acute leukemia, with an OR of 1.1 (95% CI: 0.9-1.4). Moreover, they observed a moderate risk (OR = 1.3; 95% CI: 1.0-1.7) when the children were breastfed for no more than 1 month, specifically in children diagnosed with common ALL. [68]

(OR = 0.6; 95% CI: 0.5-0.8) and breastfeeding (OR = 0.7; 95% CI: 0.5-1.0) were found to be protective factors for this disease, as was also found in children who had visited farms often in their first year of life, with an OR of 0.4 (95% CI: 0.3-0.6). No significant association was found for assistance of the child in daycare before one year of age (OR = 0.8; 95% CI: 0.6-1.1). One can conclude that repeated infections, such as asthma, play an important role in the eti‐

Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence

http://dx.doi.org/10.5772/52717

177

Moreover, Urayama et al., in the USA, conducted two epidemiological studies, namely a case-control study and a meta-analysis. The first study showed that in non-Hispanic white children who attended day care before 6 months of age, the risk of developing leukemia was decreased (OR = 0.90; 95% CI: 0.82-1.00), but this association was not observed in the popu‐ lation of Hispanic children. However, Hispanic children who had ear infections were found to have a decreased risk of developing acute leukemia, with an OR of 0.45 (95% CI: 0.25 to 0.79). Did not report any associations for the other variables studied. In the second study (meta-analysis), these authors evaluated the association between daycare attendance during infancy and the risk of developing acute leukemia; specifically, they wanted to assess whether early exposure to infection protected children from the disease. They concluded that the risk of developing acute leukemia was decreased in children who were exposed to common infections in the first year of life (OR = 0.76; 95% CI: 0.67 to 0.87). [24,25] These find‐ ings are consistent with the findings of Perillat et al., Jourdan-Da et al., Dockerty et al., and

In New Zealand, Dockerty et al. conducted a case-control study that included 121 children diagnosed with acute leukemia and 303 controls (with ages less than 14 years in both groups). They found that exposure to the influenza virus is a risk factor for developing leu‐ kemia; that is, a child infected with the influenza virus during the first year of life has a 7 fold risk of developing acute leukemia compared with children who had influenza, with an

Cardwell et al., using a different epidemiological case-control nested design in a cohort, re‐ ported positive evidence of upper respiratory tract infections as a risk factor for the develop‐ ment of acute leukemia (OR = 1.56; 95% CI: 1.08-2.27) and acute lymphoblastic leukemia (OR = 1.59; 95% CI: 1.02-2.49). Similarly, in children presenting with an exanthematous disease, namely chicken pox, we obtained ORs of 2.41 (95% CI: 1.14-5.09) and 2.62 (95% CI: 1.12-6.13)

MacArthur et al. conducted a study that included 399 cases and 399 controls who were matched for age and gender and lived in the same area. They evaluated the relationship be‐ tween vaccination, infectious diseases and common infection and use of medications in chil‐ dren, but their results were not statistically significant, as they found no relationship

Chan et al. performed a population-based, case-control study in China and found that the incidence of roseola and/or fever rash in the first year of life is a protective factor for the development of acute leukemia, with an OR of 0.33 (95% CI: 0.16 to 0.68); however, the risk of developing acute leukemia was increased if the child had a history of tonsillitis in

for acute leukemia and acute lymphoblastic leukemia, respectively. [83]

between childhood diseases and acute leukemia.[84]

ology of leukemia. [82]

Ma X et al. [15-19,21,22]

OR of 6.8 (95% CI: 1.8-25.7). [15,32]

Neglia et al. performed a case-control study in children under 15 years of age in the U.S. The cases of newly diagnosed ALL were ascertained from the Children's Cancer Group (CCG), and the controls were randomly selected using a random digit-dialing methodology and in‐ dividually matched to the cases by age, race and telephone area code and exchange between January 1, 1989, and June 15, 1993. They observed a slight decrease in the risk of developing acute leukemia when the child had repeated ear infections during their first year of life, with ORs of 0.86 (95% CI: 0.61-1.22), 0.83 (95% CI: 0.63-1.09) and 0.71 (95% CI: 0.50-1.01) for 1 epi‐ sode, 2-4 episodes and 5 or more episodes, respectively, and continuous infections were as‐ sociated with an OR of 0.69 (95% CI: 0.35-1.37; p = 0.026), but these results were not statistically significant. Moreover, it should be noted that these results are similar to a doseresponse gradient, as the risk of developing acute leukemia was decreased with an increas‐ ing number of infections in the child during the first year of life. This association was more evident in children aged 2 to 5 years with pre-B ALL who presented with ear infections (be‐ tween 2 and 4 episodes), with an OR of 0.65 (95% CI: 0.43-1.00). No other factor studied was associated with the development of acute leukemia. Furthermore, no association was ob‐ served between day care and the development of common acute lymphoblastic leukemia (ALL), with an OR of 1.05 (95% CI: 0.80-1.37). [32]

Using a design similar to that of Perillat et al. (2002) and Neglia et al. (2000), Jourdan-Da et al. evaluated the role of childhood infections in the risk of developing acute leukemia in France. This study included 473 cases of acute leukemia and 567 population-based controls. They found a strong inverse association between gastrointestinal infections and the need to assist the child in day care, with an OR of 0.6 (95% CI: 0.4-0.8). Additionally, a history of asthma decreases the risk of developing leukemia (OR = 0.5; 95% CI: 0.3-0.9). Breastfeeding was not associated with the development of leukemia, but an increasing order of the child's birth increases the risk of developing acute lymphoblastic leukemia, with an OR of 2.0 (95% CI: 1.1-3.7). [15,16,32]

Meanwhile, Rudant et al., also in France, used a case-control design of a National Register (ESCALE) and included 765 incident cases of acute leukemia and 1,681 controls. They ob‐ served positive associations when the child presented with recurrent common infections, a history of asthma or a history of eczema, with ORs of 0.7 (95% CI: 0.6-0.9), 0.7 (95% CI: 0.4-1.0) and 0.7 (95% CI: 0.6 -0.9), respectively. Having regular contact with farm animals (OR = 0.6; 95% CI: 0.5-0.8) and breastfeeding (OR = 0.7; 95% CI: 0.5-1.0) were found to be protective factors for this disease, as was also found in children who had visited farms often in their first year of life, with an OR of 0.4 (95% CI: 0.3-0.6). No significant association was found for assistance of the child in daycare before one year of age (OR = 0.8; 95% CI: 0.6-1.1). One can conclude that repeated infections, such as asthma, play an important role in the eti‐ ology of leukemia. [82]

However, Schüz et al. (1999) conducted a case-control study in Germany during 1992-1997. They studied 1184 families of children with acute leukemia (cases) and 2588 families of healthy children (controls) and found no association between common infections and an in‐ creased incidence of leukemia. It is notable, however, that they reported that when the chil‐ dren had a history of surgical procedures, such as appendectomy/tonsillectomy, at least once in their life, their risk of developing acute leukemia increased, with an OR of 1.4 (95% CI: 1.0-1.9). These authors also observed a significant association with pneumonia, with an OR of 1.7 (95% CI: 1.2-2.3), whereas bronchitis was not associated with the development of acute leukemia, with an OR of 1.1 (95% CI: 0.9-1.4). Moreover, they observed a moderate risk (OR = 1.3; 95% CI: 1.0-1.7) when the children were breastfed for no more than 1 month,

Neglia et al. performed a case-control study in children under 15 years of age in the U.S. The cases of newly diagnosed ALL were ascertained from the Children's Cancer Group (CCG), and the controls were randomly selected using a random digit-dialing methodology and in‐ dividually matched to the cases by age, race and telephone area code and exchange between January 1, 1989, and June 15, 1993. They observed a slight decrease in the risk of developing acute leukemia when the child had repeated ear infections during their first year of life, with ORs of 0.86 (95% CI: 0.61-1.22), 0.83 (95% CI: 0.63-1.09) and 0.71 (95% CI: 0.50-1.01) for 1 epi‐ sode, 2-4 episodes and 5 or more episodes, respectively, and continuous infections were as‐ sociated with an OR of 0.69 (95% CI: 0.35-1.37; p = 0.026), but these results were not statistically significant. Moreover, it should be noted that these results are similar to a doseresponse gradient, as the risk of developing acute leukemia was decreased with an increas‐ ing number of infections in the child during the first year of life. This association was more evident in children aged 2 to 5 years with pre-B ALL who presented with ear infections (be‐ tween 2 and 4 episodes), with an OR of 0.65 (95% CI: 0.43-1.00). No other factor studied was associated with the development of acute leukemia. Furthermore, no association was ob‐ served between day care and the development of common acute lymphoblastic leukemia

Using a design similar to that of Perillat et al. (2002) and Neglia et al. (2000), Jourdan-Da et al. evaluated the role of childhood infections in the risk of developing acute leukemia in France. This study included 473 cases of acute leukemia and 567 population-based controls. They found a strong inverse association between gastrointestinal infections and the need to assist the child in day care, with an OR of 0.6 (95% CI: 0.4-0.8). Additionally, a history of asthma decreases the risk of developing leukemia (OR = 0.5; 95% CI: 0.3-0.9). Breastfeeding was not associated with the development of leukemia, but an increasing order of the child's birth increases the risk of developing acute lymphoblastic leukemia, with an OR of 2.0 (95%

Meanwhile, Rudant et al., also in France, used a case-control design of a National Register (ESCALE) and included 765 incident cases of acute leukemia and 1,681 controls. They ob‐ served positive associations when the child presented with recurrent common infections, a history of asthma or a history of eczema, with ORs of 0.7 (95% CI: 0.6-0.9), 0.7 (95% CI: 0.4-1.0) and 0.7 (95% CI: 0.6 -0.9), respectively. Having regular contact with farm animals

specifically in children diagnosed with common ALL. [68]

176 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

(ALL), with an OR of 1.05 (95% CI: 0.80-1.37). [32]

CI: 1.1-3.7). [15,16,32]

Moreover, Urayama et al., in the USA, conducted two epidemiological studies, namely a case-control study and a meta-analysis. The first study showed that in non-Hispanic white children who attended day care before 6 months of age, the risk of developing leukemia was decreased (OR = 0.90; 95% CI: 0.82-1.00), but this association was not observed in the popu‐ lation of Hispanic children. However, Hispanic children who had ear infections were found to have a decreased risk of developing acute leukemia, with an OR of 0.45 (95% CI: 0.25 to 0.79). Did not report any associations for the other variables studied. In the second study (meta-analysis), these authors evaluated the association between daycare attendance during infancy and the risk of developing acute leukemia; specifically, they wanted to assess whether early exposure to infection protected children from the disease. They concluded that the risk of developing acute leukemia was decreased in children who were exposed to common infections in the first year of life (OR = 0.76; 95% CI: 0.67 to 0.87). [24,25] These find‐ ings are consistent with the findings of Perillat et al., Jourdan-Da et al., Dockerty et al., and Ma X et al. [15-19,21,22]

In New Zealand, Dockerty et al. conducted a case-control study that included 121 children diagnosed with acute leukemia and 303 controls (with ages less than 14 years in both groups). They found that exposure to the influenza virus is a risk factor for developing leu‐ kemia; that is, a child infected with the influenza virus during the first year of life has a 7 fold risk of developing acute leukemia compared with children who had influenza, with an OR of 6.8 (95% CI: 1.8-25.7). [15,32]

Cardwell et al., using a different epidemiological case-control nested design in a cohort, re‐ ported positive evidence of upper respiratory tract infections as a risk factor for the develop‐ ment of acute leukemia (OR = 1.56; 95% CI: 1.08-2.27) and acute lymphoblastic leukemia (OR = 1.59; 95% CI: 1.02-2.49). Similarly, in children presenting with an exanthematous disease, namely chicken pox, we obtained ORs of 2.41 (95% CI: 1.14-5.09) and 2.62 (95% CI: 1.12-6.13) for acute leukemia and acute lymphoblastic leukemia, respectively. [83]

MacArthur et al. conducted a study that included 399 cases and 399 controls who were matched for age and gender and lived in the same area. They evaluated the relationship be‐ tween vaccination, infectious diseases and common infection and use of medications in chil‐ dren, but their results were not statistically significant, as they found no relationship between childhood diseases and acute leukemia.[84]

Chan et al. performed a population-based, case-control study in China and found that the incidence of roseola and/or fever rash in the first year of life is a protective factor for the development of acute leukemia, with an OR of 0.33 (95% CI: 0.16 to 0.68); however, the risk of developing acute leukemia was increased if the child had a history of tonsillitis in the period 3-12 months before the reference date (OR = 2.56; 95% CI: 1.22-5.38). No associ‐ ation was found between acute leukemia incidence and daycare attendance. In a study similar to that of Chan et al., Roman et al. found that exposure to fungal infections dur‐ ing the first year of life increases the risk of developing acute leukemia, with an OR of 1.4 (95% CI: 1.0-1.9).[14,85]

questionnaires and serological tests were conducted

http://dx.doi.org/10.5772/52717

179

Social class; marital status; ethnic group; educational level of the parent; home ownership; length of gestation; age of the mother at the child's birth; weight of the child at birth; exposure of the mother to Xrays during the first trimester; exposure of the child to X-rays or radiotherapy before onset of the illness; tobacco smoking by the mother in the first trimester or before the pregnancy

A positive association was found between infection caused by influenza during the first year of life and the risk of developing leukemia (OR: 6.8; 95% CI: 1.8-25.7). No other variable was related to acute

leukemia.

2000 (USA)

Rosenbaum et al.,

Case-control study (1980-1991)

255 cases, 760 controls; Age: 0-14 years; 31 county regions (cases)

Standardized questionnaires mailed to the parents

Gender; race; educational level of the mother; birth order; feeding status at birth (breast, bottle); age at the diagnosis; day care or preschool program; family outcome; maternal employment during the

Children who attended day care for >36 months had a lower risk of developing leukemia (OR: 1.32, 95% CI: 0.70-2.52) than those who attended day care for 1-18 months (OR: 1.74; 95% CI:

pregnancy

Variables Breastfeeding; birth order; family

Odds ratios and relevant results

**Author, Year (Country)**

Odds ratios and relevant results

size; social class; number of rooms in the household; infections; hospitalization or consultation for infections; primary infections (measles, chicken pox, mumps, or rubella); periods of fever

Common colds (RR: 0.8, 95% CI: 0.6-1.0); periods of fever (RR: 0.9; 95% CI: 0.7-1.2); and primary infections (RR: 0.8; 95% CI: 0.4-2.0). These variables were adjusted for birth order, family size, social class, and residential space. Infectious diseases requiring hospitalization (RR: 0.6; 95% IC:

(January 1, 1989-June 15,1993)

age; race; educational level of the mother; educational level of the father; family income; immunophenotype class.

Neither attendance at nor time remaining in daycare was associated with the risk of developing leukemia. For children with 1-4 episodes of ear infections or sustained infections, the association between infections and

Data collection Structured interview Structured questionnaire

0.4-1.0).

Size of sample 1842 cases, 1986 controls; Age: <15 years

Variables Interview of the mother; gender;

Design of study Case-control study

Neglia et al., 2000 (USA)

First-born child; duration of breastfeeding; deficit in social contacts; routine immunizations; infections; tonsillectomy or appendectomy; allergies of the child; allergies of the mother

Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence

Routine immunizations between 0-3 years of age and having had a tonsillectomy or appendectomy increased the child's risk of developing leukemia (OR: 3.2; 95% CI: 2.3-4.6 and OR: 1.4; 95% CI: 1.1-1.9, respectively), whereas allergies showed a protective effect (OR: 0.6; 95% IC: 0.5-0.8).

Infante et al., 2000 (Canada)

telephone

respectively).

Case-control study (1989-1995)

491 cases, 491 controls; Age: 0-9 years

administered to the mothers by

Educational level of the mother; family income at the time of the child's diagnosis; mother's age; father's age; tobacco use by the mother; infections during the pregnancy; child's birth order; attendance at day care or a nursery; principal feeding method (breast or bottle); length of breastfeeding; history of recurrent infections of the mother; use of antibiotics during pregnancy

Early attendance at daycare or at a nursery and breastfeeding were protective factors against the development of acute leukemia (OR: 0.49; 95% CI: 0.31-0.77 and OR: 0.68; 95% CI: 0.49-0.95,

## **4. Infections during the first year of life and development of acute leukemia in children with Down syndrome**

In the literature, there are few epidemiological studies that have evaluated the effect of early infections and breastfeeding on the development of acute leukemia in children with Down syndrome; however, the results obtained are very interesting. One such study was conduct‐ ed by Canfield et al. in a population of children diagnosed with acute leukemia between Jan‐ uary 1997 and October 2002 (data were obtained from the records of the Children's Oncology Group). The sample group consisted of 158 children with Down syndrome and leukemia, and the control group consisted of 173 children with Down syndrome, all of whom were randomly selected. The results of this study were that children with Down syn‐ drome who had infections during the first 2 years of life had a lower risk of developing acute leukemia, with an OR of 0.55 (95% CI: 0.33 to 0.92), compared with children with Down syndrome who had not been infected. [86,87]

In another study that was conducted in children with Down syndrome in Mexico City, how‐ ever, this association could not be verified. That study sought to assess whether breastfeed‐ ing and infections during the first year of life were associated with the development of acute leukemia. In that study, both breastfeeding and the development of infections during the first year of life in children with Down syndrome were protective factors for the develop‐ ment of leukemia, with ORs of 0.84 (95% CI: 0.43-1.61) and 1.70 (95% CI: 0.82-3.52), respec‐ tively, but the results were not statistically significant. Infections requiring hospitalization were also evaluated, and it was found that children >6 years of age had a higher risk of de‐ veloping acute leukemia, with an OR of 3.57 (95% CI: 1.59-8.05). Thus, these results do not support those of the previously mentioned study or the hypothesis proposed by Greaves that infections are a protective factor for developing acute leukemia. [88]


#### Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence http://dx.doi.org/10.5772/52717 179


the period 3-12 months before the reference date (OR = 2.56; 95% CI: 1.22-5.38). No associ‐ ation was found between acute leukemia incidence and daycare attendance. In a study similar to that of Chan et al., Roman et al. found that exposure to fungal infections dur‐ ing the first year of life increases the risk of developing acute leukemia, with an OR of 1.4

In the literature, there are few epidemiological studies that have evaluated the effect of early infections and breastfeeding on the development of acute leukemia in children with Down syndrome; however, the results obtained are very interesting. One such study was conduct‐ ed by Canfield et al. in a population of children diagnosed with acute leukemia between Jan‐ uary 1997 and October 2002 (data were obtained from the records of the Children's Oncology Group). The sample group consisted of 158 children with Down syndrome and leukemia, and the control group consisted of 173 children with Down syndrome, all of whom were randomly selected. The results of this study were that children with Down syn‐ drome who had infections during the first 2 years of life had a lower risk of developing acute leukemia, with an OR of 0.55 (95% CI: 0.33 to 0.92), compared with children with

In another study that was conducted in children with Down syndrome in Mexico City, how‐ ever, this association could not be verified. That study sought to assess whether breastfeed‐ ing and infections during the first year of life were associated with the development of acute leukemia. In that study, both breastfeeding and the development of infections during the first year of life in children with Down syndrome were protective factors for the develop‐ ment of leukemia, with ORs of 0.84 (95% CI: 0.43-1.61) and 1.70 (95% CI: 0.82-3.52), respec‐ tively, but the results were not statistically significant. Infections requiring hospitalization were also evaluated, and it was found that children >6 years of age had a higher risk of de‐ veloping acute leukemia, with an OR of 3.57 (95% CI: 1.59-8.05). Thus, these results do not support those of the previously mentioned study or the hypothesis proposed by Greaves

> Schüz et al., 1999 (Germany)

(1980-1994)

0-14 years

parents

Two-part case-control study

1184 cases, 2588 controls; Age:

Telephone interviews with the

Dockerty et al., 1999 (New Zealand)

Case-control study (1991-1995)

121 cases, 303 controls; Age: 0-14 years

Mothers interviewed at the home; standardized

that infections are a protective factor for developing acute leukemia. [88]

**4. Infections during the first year of life and development of acute**

**leukemia in children with Down syndrome**

178 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Down syndrome who had not been infected. [86,87]

(95% CI: 1.0-1.9).[14,85]

**Author, Year (Country)**

Van Steensel et al.,

(The Netherlands)

Data collection Mailed questionnaire; addressed to the diagnosed

1986

Size of sample 492 cases, 480 controls; Age: 0-14 years

Design of study Case-control study (1973-1980)


Size of sample 255 cases, 760 controls; Age: 0-14 years

Variables Gender; race; birth year; mother's

diarrhea)

Odds ratios and relevant results

**Author, Year (Country)**

educational level; family income; maternal smoking status; infant feeding at birth; birth order; attendance at daycare before 25 months of age; year of diagnosis of leukemia; age at diagnosis of leukemia; allergies; history of allergies; common infections (e.g., colds, otitis media, influenza, croup, bronchiolitis, pneumonia, vomiting,

The results showed that infection late in the first year of the child's life was associated with an increase in the risk

of developing leukemia.

MacArthur et al.,

Design of study Population-based, case-control study

Data collection Standardized personal interviews in the child's home

Variables Gender; age; mother's age; father's

(January 1,1990 - December 31,1994)

age; numbers of live births; annual household income; mother's education; father's education; ethnicity; vaccinations; illness and infections; breastfeeding; allergies; immunosuppressant medication for the child; vitamins; antibiotics for the

No association was found between early infections and acute leukemia; however, vitamin use was associated with a risk of developing acute leukemia (OR; 1.66; (95% CI: 1.18-2.33); the use of

2007 (Canada)

Size of sample 399 cases, 399 controls; Age: 0-14 years

child

Odds ratio and relevant results 294 incident cases, 376 controls;

Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence

Age; gender; household income; mother's educational level; mother's age at birth; birth weight; birth order; duration of breastfeeding; day care attendance; infections during

Attendance at daycare and infections during infancy were associated with a decrease in the risk of developing acute lymphoblastic leukemia within the white, Hispanic population (OR: 0.42; 95% CI: 0.18-0.99 and OR: 0.32; 95% CI: 0.14-0.74, respectively); corresponding data for the Hispanic population, even for those living in the same area,

did not agree.

Cardwell et al., 2008

Nested case-control (cohort) study

controls

Data-based

0.69-1.59;

(United Kingdom)

62 cases, 2215 matched

Gender; age; consultations; number of consultations; antibiotic prescriptions; common infections

One or more infections in the first year of life reduced the risk of leukemia (OR: 10.5; 95% CI:

455 cases, 1031 controls; Age: 0-14 years

http://dx.doi.org/10.5772/52717

181

Gender; age; diagnosis of an infectious disease

The cases had more episodes of infection than did the controls, which was more notable in the neonatal period (≤1 month): 18% of the controls and 24% of the cases with leukemia were diagnosed with an average of <1 infection (OR: 1.4; 95% CI: 1.1-1.9; p < 0.05). The cases with ≥1 episodes of infection in the neonatal period tended to be diagnosed with acute lymphoblastic leukemia at a relatively young age.

Urayama et al., 2010 (USA)

Case-control study (1995-1999)

669 cases, 977 controls; Age: 1-14 years

Gender; mother's age at the child's birth; mother's educational level; annual household income; birth weight; breastfeeding; mother's tobacco use; daycare attendance; history of common infections in the

child; ethnicity

When variables were evaluated separately, both attendance at daycare at 6 months of age and birth order reduced the risk of leukemia (OR: 0.90; 95% CI:

Age: 0-14 years

Data collection Questionnaire Personal interview of the parents Interview of the parents

infancy


the development of acute leukemia was not statistically significant.

Design of study Case-control study Population-based, case-control

180 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Chan et al., 2002 (China)

1997)

interviews

study (November 1994-December

116 cases, 788 controls; Age: 2-14 years; the Hong Kong Pediatric Hematology and Oncology Study Group

Standardized, face-to-face

Medical history (infectious illnesses) in the first year of life; breastfeeding; daycare/social contacts of the index patient and siblings; household environment; community environment

If the child had rubella and/or fever during the first year of life, the risk was lowered (OR: 0.33; 95% CI: 0.16-0.68). A change of residence during the first year of life presented a lower risk of the child developing leukemia (OR: 0.47; 95% CI: 0.23-0.98), whereas with such a change during the second year, the risk increased (OR: 3.92; 95% CI: 1.47-10.46).

Ma et al., 2005 (USA)

Perillat et al., 2002 (France)

288 hospital controls

Data collection Standardized, face-to-face interviews of the mothers

> leukemia classification and immunophenotype); gender; age; ethnic origin; hospital where the case was identified; educational level of the mother; occupation of the mother at the time of the interview; socio-professional categories; place of residence; birth order; number of siblings; daycare attendance; age at the start of daycare; repeated infections before the age of 2 years; incidence of surgical operation for early ear-nose-throat infections before the age of 2 years;

Variables Diagnosed categories (acute

breastfeeding

infections.

2005 (USA)

Rosenbaum et al.,

Design of study Population-based, case-control study (1980-1991)

An inverse association was found between the development of acute leukemia and attendance at daycare (OR: 0.6; 95% CI: 0.4-1.0), repeated (≥4 per year) early common infections before the age of 2 years (OR: 0.6; 95% CI: 0.4-1.0), and surgery for infection of the nose, ear, or throat before the age of 2 years (OR: 0.5; 95% CI: 0.2-1.0). A statistically significant interaction was found between attendance at daycare and repeated common

Odds ratios and relevant results

**Author, Year (Country)**

Size of sample 280 incident cases,

**Author, Year (Country)**

0.89-3.42) or for 19-36 months (OR: 1.32; 95% CI:

0.64-2.71).

473 cases,

Questionnaire

2004 (France)

Jourdan-Da et al.,

Case-control study (1995-1998)

567 population-based controls

Gender; age at the time of diagnosis; region of the residence at the time of diagnosis; socio-professional categories; educational level of the mother; educational level of the father; birth weight; term of pregnancy; birth order; mother's age at birth; Down syndrome; breastfeeding; infections in the first year of life

A strong association was found

between childhood gastrointestinal illnesses and attendance at daycare and a lowered risk of developing leukemia (OR: 0.6; 95% CI: 0.4-0.8); however, no association was found for breastfeeding. Birth order (4th or later) showed a significant association with an increased risk of acute lymphoblastic leukemia (OR: 2.0; 95% CI: 1.1-3.7), while prior episodes of asthma were associated with a lower risk of developing acute lymphoblastic leukemia (OR: 0.5; 95% CI: 0.3-0.9).

Roman et al., 2007

(United Kingdom)

study (1991-1996)

Population-based, case-control


0.82-1.00 and OR: 0.68; 95% CI: 0.50-0.92, respectively) in a white, non-Hispanic population, but not in a Hispanic population; however, if these children had ear infections, the risk of developing acute leukemia was reduced (OR: 0.45, 95% CI: 0.25-0.79).

posed to early infections compared with those who were not exposed. No such association, however, has been reported by other authors; therefore, infections that occur during the first year of life are still considered to be a controversial exposure factor. To achieve better epide‐ miological evidence, the consistent study of proxy variables in different studies should be

Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence

http://dx.doi.org/10.5772/52717

183

This work was funded by the Consejo Nacional de la Ciencia y la Tecnología (CONACYT) through its program, Fondo Sectorial de Investigación en Salud y Seguridad Social (SALUD 2007-1-71223/FIS/IMSS/PROT/592); the Fondo Sectorial de Investigación para la Educación (CB-2007-1-83949/FIS/IMSS/PROT/616) and by Instituto Mexicano del Seguro Social (FIS/

Janet Flores-Lujano, Juan Carlos Núñez-Enríquez, Angélica Rangel-López,

Century, Mexican Institute of Social Insurance (IMSS), Mexico City, Mexico

London XIX. British Journal of Children's Diseases. 1922,128

\*Address all correspondence to: arangurejm@hotmail.com

David Aldebarán-Duarte, Arturo Fajardo-Gutiérrez and Juan Manuel Mejía-Aranguré\*

Research Unit in Clinical Epidemiology, Hospital of Pediatrics, National Medical Center 21st

[1] Ward, G. The infective theory of acute leukemia. British Journal of Children's Diseas‐

[2] Poynton, F.; Thursfield, H. & Paterson, D. The Severe Blood Diseases of Childhood,

[3] Kellet, C. Acute myeloid leukemia in one of identical twins. Archives of disease in

[4] Cooke, J. V. The incidence of acute leukemia in children. The Journal of the American

[5] Kinlen, L. Epidemiological evidence for an infective basis in childhood leukaemia.

performed to enable a better quantification of exposure.

**Acknowledgements**

IMSS/PROT/G10/846).

**Author details**

**References**

es 1917; 14 10-20

childhood 1937;12(70) 239-252

Medical Association 1942; 119 547-550

British Journal of Cancer 1995;71(1) 1-5


**Table 1.** Summary of reviewed articles concerning the epidemiology of early infection and acute childhood leukemia.

#### **5. Conclusions**

The vast majority of the epidemiological studies conducted thus far on the association be‐ tween infection during the first year of life and the development of acute leukemia in chil‐ dren have corresponding case-control designs. Additionally, the results of these studies appear to suggest a lower risk of developing acute leukemia among children who were ex‐ posed to early infections compared with those who were not exposed. No such association, however, has been reported by other authors; therefore, infections that occur during the first year of life are still considered to be a controversial exposure factor. To achieve better epide‐ miological evidence, the consistent study of proxy variables in different studies should be performed to enable a better quantification of exposure.

## **Acknowledgements**

immunosuppressants by the child decreased the risk of leukemia (OR: 0.37; 95% CI: 0.16-0.84); breastfeeding for >6 months had a protective effect against the development of leukemia (p < 0.05).

182 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Rudant J et al., 2010 (France)

Size of sample 765 incident cases,

Design of study National registry-based, case-control study ESCALE (2003-2004)

1,681 controls.

Variables Mother's educational level; parental

professional category; place of residence at the time of diagnosis; mother's age at the child's birth; number of children age <15 years in the household; birth order; breastfeeding; duration of breastfeeding; early common infections; surgical operation for ear, nose, or throat infections; history of allergies; contact with animals; farm visits before the age of 2 years

Negative associations were found for children with repeated common infections (OR: 0.7; 95% CI: 0.6-0.9); with a history of asthma or eczema (OR: 0.7; 95% CI: 0.4-1.0 and OR: 0.7; 95% CI: 0.6-0.9, respectively); with attendance at daycare before 1 year of age (OR: 0.8; 95% CI: 0.6-1.1); and with prolonged breastfeeding (OR:

0.7; 95% CI: 0.5-1.0).

Data collection Questionnaire, interviews by telephone

**Author, Year (Country)**

Odds ratios and relevant results

**5. Conclusions**

p = 0.83) and of acute

Urayama et al., 2011 (USA)

Observational studies (1993-2008)

14 case-control study

Attendance at daycare is associated with a reduced risk of acute lymphoblastic leukemia (OR: 0.76; 95% CI: 0.67-0.87).

**Table 1.** Summary of reviewed articles concerning the epidemiology of early infection and acute childhood leukemia.

The vast majority of the epidemiological studies conducted thus far on the association be‐ tween infection during the first year of life and the development of acute leukemia in chil‐ dren have corresponding case-control designs. Additionally, the results of these studies appear to suggest a lower risk of developing acute leukemia among children who were ex‐

publications

N/A

Searches of the PubMed database and bibliographies of the

lymphoblastic leukemia (OR: 1.05; 95% CI: 0.64-1.74; p = 0.84).

0.82-1.00 and OR: 0.68; 95% CI: 0.50-0.92, respectively) in a white, non-Hispanic population, but not in a Hispanic population; however, if these children had ear infections, the risk of developing acute leukemia was reduced (OR: 0.45, 95%

CI: 0.25-0.79).

This work was funded by the Consejo Nacional de la Ciencia y la Tecnología (CONACYT) through its program, Fondo Sectorial de Investigación en Salud y Seguridad Social (SALUD 2007-1-71223/FIS/IMSS/PROT/592); the Fondo Sectorial de Investigación para la Educación (CB-2007-1-83949/FIS/IMSS/PROT/616) and by Instituto Mexicano del Seguro Social (FIS/ IMSS/PROT/G10/846).

## **Author details**

Janet Flores-Lujano, Juan Carlos Núñez-Enríquez, Angélica Rangel-López, David Aldebarán-Duarte, Arturo Fajardo-Gutiérrez and Juan Manuel Mejía-Aranguré\*

\*Address all correspondence to: arangurejm@hotmail.com

Research Unit in Clinical Epidemiology, Hospital of Pediatrics, National Medical Center 21st Century, Mexican Institute of Social Insurance (IMSS), Mexico City, Mexico

## **References**


[6] Kinlen, L.; Dickson, M. & Stiller, C. Childhood leukemia and non-Hodgkin's lympho‐ ma near large rural construction sites, with a comparison with Sellafield nuclear site. British Journal of Cancer 1995;310 763-768

[18] Ma, X.; Metayer, C.; Does, M. &Buffler, P. Maternal pregnancy loss, birth characteris‐ tics, and childhood leukemia (United States). Cancer Causes & Control 2005;16(9)

Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence

http://dx.doi.org/10.5772/52717

185

[19] Ma, X.; Urayama, K.; Chang, J.; Wiemels, J. &Buffler, P. Infection and pediatric acute lymphoblastic leukemia. Blood Cells, Molecules & Diseases 2009;42(2) 117-120

[20] Roman, E.; Simpson, J.; Ansell, P.; Lightfoot, T. & Smith, A. Infectious proxies and childhood leukemia: Findings from the United Kingdom Childhood Cancer Study

[21] Perillat, F.; Clavel, J.; Jaussent, I.; Baruchel, A.; Leverger, G.; Nelken, B.; Philippe, N.; Schaison, G.; Sommelet, D.; Vilmer, E. &Hemon, D. Breast-feeding, fetal loss and

[22] Perrillat, F.; Clavel, J.; Auclerc, M.; Baruchel, A.; Leverger, G.; Nelken, B.; Philippe, N.; Schaison, G.; Sommelet, D.; Vilmer, E. &Hémon, D. Day-care, early common in‐ fections and childhood acute leukaemia: a multicentre French case-control study.

[23] Rosenbaum, P.; Buck, G. &Brecher, M. Early child-care and preschool experiences and the risk of childhood acute lymphoblastic leukemia. American Journal of Epi‐

[24] Urayama, K.; Buffler, P.; Gallagher, E.; Ayoob, J. & Ma, X. A meta-analysis of the as‐ sociation between day-care attendance and childhood acute lymphoblastic leukae‐

[25] Urayama, K.; Ma, X.; Selvin, S.; Metayer, C.; Chokkalingam, A.; Wiemels, J.; Does, M.; Chang, J.; Wong, A.; Trachtenberg, E. &Buffler, P. Early life exposure to infec‐ tions and risk of childhood acute lymphoblastic leukemia. International Journal of

[26] Githens, J.; Elliot, F. & Saunders, L. The relation of socioeconomic factors to incidence

[27] Alexander, F.; Cartwright, R.; McKinney, P. & Ricketts, T. Leukaemia incidence, so‐ cial class and estuaries: an ecological analysis. Journal of Public Health Medicine,

[28] Draper, GJ. The Geographical Epidemiology of Childhood Leukaemia and Non-Hodgkin Lymphomas in Great Britain, 1966–83, OPCS Studies on Medical and Popu‐

[29] Stiller, C. & Boyle, P. Effect of population mixing and socioeconomic status in Eng‐ land and Wales, 1979–85, on lymphoblastic leukaemia in children. British Medical

mia. International Journal of Epidemiology 2010;39(3) 718–732

of childhood leukemia. Public Health Reports 1965;80 573–578

lation Subjects No. 53 1991. London: OPCS; (ed).

childhood acute leukemia. European Journal of Pediatrics 2002;161(4) 235-237

(UKCCS). Blood Cells, Molecules and Diseases 2009;42(2) 126–128

British Journal of Cancer 2002;8(86) 1064-1069

demiology 2000;152(12) 1136-1144

Cancer 2011;128(7) 632-643

Journal 1996;313 1297–1300

1990;12(2) 109–117

1075-1083


[18] Ma, X.; Metayer, C.; Does, M. &Buffler, P. Maternal pregnancy loss, birth characteris‐ tics, and childhood leukemia (United States). Cancer Causes & Control 2005;16(9) 1075-1083

[6] Kinlen, L.; Dickson, M. & Stiller, C. Childhood leukemia and non-Hodgkin's lympho‐ ma near large rural construction sites, with a comparison with Sellafield nuclear site.

[7] Kinlen, L. Evidence for an infective cause of childhood leukaemia: comparison of a Scottish new town with nuclear reprocessing sites in Britain. Lancet 1998;2(8624)

[8] Greaves, M. Speculations on the cause of childhood acute lymphoblastic leukemia.

[9] Greaves, MF & Alexander, FE. An infectious etiology for common acute lymphoblas‐

[10] Greaves, M.; Colman, S.; Beard, M.; Bradstock, K.; Cabrera, M.; Chen, PM.; Jacobs, P.; Lam-Po-Tan, P.; MacDougall, L. & Williams, C. Geographical distribution of acute lymphoblastic leukemia subtypes: second report of the collaborative group study.

[11] Greaves, M. & Alexander, F. Epidemiological characteristics of childhood acute lym‐

[12] Greaves, M. Science, Medical and the future: Childhood leukaemia. British Medical

[13] Greaves, M. Infection, immune responses and the aetiology of childhood leukemia.

[14] Chan, L.; Lam, T.; Li, C.; Lau, Y.; Li, C.; Yuen, H.; Lee, C.; Ha, S.; Yuen, P.; Leung, N.; Patheal, S.; Greaves, M. & Alexander, F. Is the timing of exposure to infection a major determinant of acute lymphoblastic leukaemia in Hong Kong?.Paediatric and Perina‐

[15] Dockerty, J.; Skegg, D.; Elwood, J.; Herbison, G.; Becroft, D. & Lewis, M. Infections, vaccinations, and the risk of childhood leukaemia. British Journal of Cancer, 1999;

[16] Jourdan-Da, S.; Perel, Y.; Méchinaud, F.; Plouvier, E.; Gandemer, V.; Lutz, P.; Vanni‐ er, J.; Lamagnére, J.; Margueritte, G.; Boutard, P.; Robert, A.; Armari, C.; Munzer, M.; Millot, F.; De Lumley, L.; Berthou, C.; Rialland, X.; Pautard, B.; Hémon, D. &Clavel, J. Infectious diseases in the first year of life, perinatal characteristics and childhood

[17] Ma, X.; Buffler, P.; Wiemels, J.; Selvin, S.; Metayer, C.; Loh, M.; Does, M. &Wiencke, J. Ethnic difference in daycare attendance, early infections, and risk of childhood acute lymphoblastic leukemia. Cancer Epidemiology, Biomarkers & Prevention 2005;14(8)

acute leukaemia. British Journal of Cancer 2004; 90(1) 139-145

phocytic leukemia. Leukemia 1994;8(10) 1793-1794, ISSN 0887-6924

British Journal of Cancer 1995;310 763-768

184 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

tic leukemia in childhood? Leukemia 1993;7(3) 349-360

1323-1327

Leukemia 1988;2(2) 120-125

Leukemia 1993;7(1) 27-34

Journal 2002;2(324) 283-287

Nature Reviews Cancer 2006;6(3) 93-203

tal Epidemiology 2002;16(2) 154-165

80(9) 1483-1489

1928-1934


[30] Borugian, M.; Spinelli, J.; Mezei, G.; Wilkins, R.; Abanto, Z. & McBride, M. Child‐ hood leukemia and socioeconomic status in Canada. Epidemiology 2005;16(4) 526– 531

[42] Naumburg, E.; Bellocco, R.; Cnattingius. S.; Jonzon, A. &Ekbom, A. Perinatal expo‐ sure to infection and risk of childhood leukemia. Medical and Pediatric Oncology

Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence

http://dx.doi.org/10.5772/52717

187

[43] Wen, W.; Shu, X.; Potter, J.; Severson, R.; Buckley, J.; Reaman, G. & Robison, L. Paren‐ tal medication use and risk of childhood acute lymphoblastic leukemia. Cancer

[44] Alexander, F.; Patheal, S.; Biondi A.; Brandalise, S.; Cabrera, M.; Chan, L.; Chen, Z.; Cimino, G.; Cordoba, J.; Gu, L.; Hussein, H.; Ishii, E.; Kamel, AM.; Labra, S.; Magal‐ hães, I.; Mizutani, S.; Petridou, E.; de Oliveira, M.; Yuen, P.; Wiemels, J. & Greaves, M. Transplacental chemical exposure and risk of infant leukemia with MLL gene fu‐

[45] Shaw, A.; Infante-Rivard, C. & Morrison, H. Use of medication during pregnancy and risk of childhood leukemia (Canada). Cancer Causes Control 2004;15(9) 931-937

[46] McKinney, P.; Juszczak E.; Findlay E.; Smith K. & Thomson, C. Pre- and perinatal risk factors for childhood leukaemia and other malignancies: a Scottish case control

[47] Field, C. The immunological components of human milk and their effect on immune

[48] Macías, S.; Rodríguez, S.; &Ronayne, P. Leche materna: composición y factores con‐ dicionantes de la lactancia. ArchivosArgentinos de Pediatría 2006;104(5) 423-430

[49] Parker, L. Breast-feeding and cancer prevention. European Journal of Cancer

[50] Riveron, R. Valor inmunológico de la leche materna. Revista Cubana de Pedia‐

[51] Altinkaynak, S.; Selimoglu, M.; Turgut, A.; Kilicaslan, B. &Ertekin, V. Breast-feeding duration and childhood acute leukemia and lymphomas in a sample of Turkish chil‐

[52] Bener, A.; Denic, S. &Galadari, S. Longer Breast-feeding and protection against child‐ hood leukaemia and lymphomas. European Journal of Cancer 2001;37(2) 234-238

[53] Beral, V.; Fear, N.; Alexander, F. & Appleby, P. Breastfeeding and childhood cancer. UK Childhood Cancer Study Investigators. British Journal of Cancer 2001;85(11)

[54] [54] Davis, K. Review of the evidence for an association between infant feeding and childhood cancer. International Journal of Cancer supplement 1998;11 29-33

[55] Guise, J.; Austin, D. & Morris C. Review of case-control studies related to breastfeed‐ ing and reduced risk of childhood leukemia. Pediatrics 2005;116(5) 724-731

dren. Journal of Pediatric Gastroenterology and Nutrition 2006;42(5) 568-572

sion. The Journal of Cancer Research 2001;61(6) 2542-6

study. British Journal of Cancer 1999;80(11) 1844-51

development in infants. The Journal of Nutrition 2005;13(1) 1-4

2002;38(6) 391-397

2002;95(8) 1786-1794

2001;37(2) 55-8

1685-1694

tría1995;67(2) 1-16


[42] Naumburg, E.; Bellocco, R.; Cnattingius. S.; Jonzon, A. &Ekbom, A. Perinatal expo‐ sure to infection and risk of childhood leukemia. Medical and Pediatric Oncology 2002;38(6) 391-397

[30] Borugian, M.; Spinelli, J.; Mezei, G.; Wilkins, R.; Abanto, Z. & McBride, M. Child‐ hood leukemia and socioeconomic status in Canada. Epidemiology 2005;16(4) 526–

[31] Van Steensel, H.; Valkenburg; H. & van Zanen G. Childhood leukemia and infectious diseases in the first year of life: a register-based case-control study. American Journal

[32] Neglia, J.; Linet, M.; Shu, X.; Severson, R.; Potter, J.; Mertens, A.; Wen, W.; Kersey, J. & Robison, L. Patterns of infection and day care utilization and risk of childhood

[33] Infante, C.; Fortier, I. & Olson E. Markers of infection, breast-feeding and childhood

[34] Fedrick, J &Alberman, ED. Reported influenza in pregnancy and subsequent cancer

[35] Kaatsch P, Scheidemann-Wesp U, Schüz J. Maternal use of antibiotics and cancer in the offspring: results of a case-control study in Germany. Cancer Causes Control

[36] Van Steensel-Moll, H.; Valkenburg, H.; Vandenbroucke, J. & van Zanen, G. Are ma‐ ternal fertility problems related to childhood leukaemia? International Journal of Epi‐

[37] Thapa, P.; Whitlock, J.; Brockman-Worrell, K.; Gideon, P.; Mitchel, E Jr.; Roberson, P.; Pais, R. & Ray, W. Prenatal Exposure to Metronidazole and Risk of Childhood Can‐ cer A Retrospective Cohort Study of Children Younger than 5 Years. Cancer

[38] Gilman, E.; Wilson, L.; Kneale, G. & Waterhouse, J. Childhood cancers and their asso‐ ciation with pregnancy drugs and illnesses. Paediatric and Perinatal Epidemiology

[39] Rodvall, Y.; Pershagen, G.; Hrubec, Z.; Ahlbom, A.; Pedersen, N. &Boice, J. Prenatal X-ray exposure and childhood cancer in Swedish twins. International Journal of Can‐

[40] vanDuijn, C.; van Steensel-Moll, H.; Coebergh, J. & van Zanen, G. Risk factors for childhood acute non-lymphocytic leukemia: An association with maternal alcohol consumption during pregnancy? Cancer Epidemiology, Biomarkers & Prevention

[41] Roman, E.; Ansell, P. & Bull, D. Leukaemia and non-Hodgkin's lymphoma in chil‐ dren and young adults: are prenatal and neonatal factors important determinants of

disease? British Journal of Cancer 1997;76(3) 406–415

acute lymphoblastic leukaemia. British Journal of Cancer 2000;82(1) 234-240

acute leukemia. British Journal of Cancer 2000;83,(11) 1559-1564

in the child. British Medical Journal, 1972;27(2) 485-488

531

of Epidemiology 1986;124(4) 590-594

186 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

2010 21(8) 1335-1345.

1998;83(7), 1461-1468

cer 1990;46(3) 362-365

1994;3(6) 457-460

1989;3(1) 66-94

demiology 1985;14(4) 555-559


[56] Ip, S.; Chung, M.; Raman, G.; Chew, P.; Magula, N.; DeVine, D.; Trikalinos, T. & Lau, J. Breastfeeding and maternal and infant health outcomes in developed countries. Evidence Report/Technology Assessment 2007;153 1-186

[70] Hartley, A.; Birch, J.; McKinney, P.; Blair, V.; Teare, M.; Carrette, J.; Mann, J.; Stiller, C.; Draper, G. & Johnston, H. The Inter-Regional Epidemiological Study of Child‐ hood Cancer (IRESCC): past medical history in children with cancer. Journal of Epi‐

Infection During the First Year of Life and Acute Leukemia: Epidemiological Evidence

http://dx.doi.org/10.5772/52717

189

[71] Nishi, M. & Miyake, H. A case-control study of non-T cell acute lymphoblastic leu‐ kaemia of children in Hokkaido, Japan. Journal of Epidemiology & Community

[72] Buckley, J.; Buckley, C.; Ruccione, K.; Sather, H.; Waskerwitz, M.; Woods, W. & Robi‐ son, L. Epidemiological characteristics of childhood acute lymphocytic leukemia. Analysis by immunophenotype. The Children's Cancer Group. Leukemia 1994;8 856–

[73] Petridou, E; Trichopoulos, D; Kalapothaki, V; Pourtsidis, A; Kogevinas, M; Kalmanti, M; Koliouskas, D; Kosmidis, H; Panagiotou, J; Piperopoulou, F. &Tzortzatou, F. The risk profile of childhood leukemia in Greece: a nationwide case-control study. British

[74] Petridou, E.; Dalamaga, M.; Mentis, A.; Skalkidou, A.; Moustaki, M.; Karpathios, T; Trichopoulos, D. & Childhood Haematologists-Oncologists Group. Evidence on the infectious etiology of childhood leukemia: the role of low herd immunity (Greece).

[75] Markiewicz MA, Gajewski TF. The immune system as anti-tumor sentinel: molecular requirements for an anti-tumor immune response. Critical Reviews in Oncogenesis.

[76] Rosenbaum, P.; Buck, G. &Brecher, M. Allergy and infectious disease histories and the risk of childhood acute lymphoblastic leukaemia. Paediatric and Perinatal Epi‐

[77] Eriksson, N.; Mikoczy, Z, &Hagmar, L. Cancer incidence in 13811 patients skin tested for allergy. Journal of Investigational Allergology& Clinical Immunology 2005;15(3)

[78] Turner, M.; Chen, Y.; Krewski, D. &Ghadirian, P. International journal of cancer. Journal international du cancer. International Journal of Cancer 2006;118(12) 3124-32

[79] Linabery, A.; Jurek, A.; Duval, S. & Ross, J. The association between atopy and child‐ hood/adolescent leukemia: a meta-analysis. American Journal of Epidemiology

[80] McNally, R. & Eden, T. An infectious aetiology for childhood acute leukaemia: a re‐ view of the evidence. British Journal of Haematology 2004;127(3) pp.243-263, [81] McNally, R.; Cairns, D.; Eden, O.; Alexander, F.; Taylor, G.; Kelsey, A. & Birch, J. (2002). An infectious aetiology for childhood brain tumours?. Evidence from spacetime clustering and seasonality analyses. British Journal of Cancer 2002;86(7)

demiology and Community Health 1988;42(3) 235–242

Health 1989;43(4) 352–355

1999;10(3):247-260

2010;171(7) 749-64

1070-1077

161-166

demiology 2005;19(2) 152-164

Journal of Cancer 1997;76(9) 1241–1247

Cancer Causes & Control 2001;12(7) 645-52

864


[70] Hartley, A.; Birch, J.; McKinney, P.; Blair, V.; Teare, M.; Carrette, J.; Mann, J.; Stiller, C.; Draper, G. & Johnston, H. The Inter-Regional Epidemiological Study of Child‐ hood Cancer (IRESCC): past medical history in children with cancer. Journal of Epi‐ demiology and Community Health 1988;42(3) 235–242

[56] Ip, S.; Chung, M.; Raman, G.; Chew, P.; Magula, N.; DeVine, D.; Trikalinos, T. & Lau, J. Breastfeeding and maternal and infant health outcomes in developed countries.

[57] Kwan, L.; Buffler, P.; Abrams, B. &Kiley, V. Breastfeeding and the risk of childhood

[58] Kwan, M.; Buffler, P.; Wiemels, J.; Metayer, C.; Selvin, S.; Ducore, J. & Block, G. Breastfeeding patterns and risk of childhood acute lymphoblastic leukaemia. British

[59] Shu, X.; Clemens, J.; Zheng, W.; Ying, D.; Ji, B. & Jin, F. Infant breastfeeding and the risk of childhood lymphoma and leukaemia. International Journal of Epidemiology

[60] Shu, X.; Linet, M.; Steinbuch, M.; Wen, W.; Buckley, J.; Neglia, J.; Potter, J.; Reaman, G. & Robison, L. Breast-feeding and risk of childhood acute leukemia. Journal Na‐

[61] Stuebe, A. The risks of not breastfeeding for mothers and infants. Reviews in Obstet‐

[62] Cushing, A.; Samet, J.; Lambert, W.; Skipper, B.; Hunt, W.; Young, S. & McLaren, L. Breastfeeding reduces risk of respiratory illness in infants. American Journal of Epi‐

[63] Lancashire, R.; Sorahan, T. & OSCC. Breastfeeding and childhood cancer risks: OSCC

[64] Paricio, J.; Lizán, M.; Otero, A.; Benlloch, M.; Beseler, B.; Sánchez, M.; Santos, L. & Rivera, L. Full breastfeeding and hospitalization as a result of infections in the first

[65] Menegaux, F.; Olshan, A.; Neglia, J.; Pollock, B. &Bondy, M. Day care, childhood in‐ fections and risk of neuroblastoma. American Journal of Epidemiology 2004;159(9)

[66] Gilham, C.; Peto, J,; Simpson J, Roman E, Eden TO, Greaves MF, Alexander FE; UKCCS Investigators. Day care in infancy and risk of childhood acute lymphoblastic leukaemia: findings from UK case-control study. British Medical Journal

[67] Kneale, G.; Stewart, A. & Wilson, L. Immunizations against infectious diseases and childhood cancers. Cancer immunology, immunotherapy 1986;21(2) 129–132

[68] Schüz, J.; Kaletsch, U.; Meinert, R.; Kaatsch, P. &Michaelis, J. Association of child‐ hood leukaemia with factors related to the immune system. British Journal of Cancer

[69] Haro, AS. The effect of BCG-vaccination and tuberculosis on the risk of leukemia.

Developments in biological standardization, (Part A), 1986;58 433-449

leukemia: a meta-analysis. Public Health Reports 2004;119(6) 521-535

Evidence Report/Technology Assessment 2007;153 1-186

188 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Journal of Cancer 2005;93(3) 379-384

tional Cancer Institute 1999;91(20) 1765-1772

data. British Journal of Cancer 2003;88(7) 1035-1037

year of life. Pediatrics 2006;118(1) e92-e99

rics and Gynecology 2009;2(4) 222-231

demiology 1998;147(9) 863-870

1995;24(1) 27-32

843-851

2005;330(7503) 1294

1999;80(3-4) 585-90


[82] Rudant, J.; Orsi, L.; Menegaux, F.; Petit, A.; Baruchel, A.; Bertrand, Y.; Lambilliotte, A.; Robert, A.; Michel, G.; Margueritte, G.; Tandonnet, J.; Mechinaud, F.; Bordigoni, P.; Hémon, D. &Clavel, J. (2010). Childhood acute leukemia, early common infec‐ tions, and allergy: The ESCALE Study. American Journal of Epidemiology 2010;172(9) 1015-1027

**Section 4**

**Prognostic of ALL**


**Section 4**

**Prognostic of ALL**

[82] Rudant, J.; Orsi, L.; Menegaux, F.; Petit, A.; Baruchel, A.; Bertrand, Y.; Lambilliotte, A.; Robert, A.; Michel, G.; Margueritte, G.; Tandonnet, J.; Mechinaud, F.; Bordigoni, P.; Hémon, D. &Clavel, J. (2010). Childhood acute leukemia, early common infec‐ tions, and allergy: The ESCALE Study. American Journal of Epidemiology

[83] Cardwell, C.; McKinney, P.; Patterson, C. & Murray, L. Infections in early life and childhood leukaemia risk: a UK case-control study of general practitioner records.

[84] MacArthur, A.; McBride, M.; Spinelli, J.; Tamaro, S.; Gallagher, R. &Theriault, G. (2008). Risk of childhood leukemia associated with vaccination, infection, and medi‐ cation use in childhood: the Cross-Canada Childhood Leukemia Study. American

[85] Roman, E.; Simpson, J.; Ansell, P.; Kinsey, S.; Mitchell, C.; McKinney, P.; Birch, J.; Greaves, M.; Eden, T. & United Kingdom Childhood Cancer Study Investigators. Childhood acute lymphoblastic leukaemia and infections in the first year of life: A re‐ port from the United Kingdom Childhood Cancer Study. American Journal of Epi‐

[86] Canfield, K.; Spector, L.; Robison, L.; Lazovich, D.; Roesler, M.; Olshan, A.; Smith, F.; Heerema, N.; Barnard, D.; Blair, C. & Ross, J. Childhood and maternal infections and risk of acute leukaemia in children with Down syndrome: a report from the Child‐

[87] Ross, J.; Spector, L.; Robison, L. &Olshon, A. Epidemiology of leukemia in children

[88] Flores, J.; Pérez, M.; Fuentes, E.; Gorodezky, C.; Bernaldez, R.; Del Campo, M.; Martí‐ nez, A.; Medina, A.; Paredes, R.; De Diego, J.; Bolea, V.; Rodríguez, M.; Rivera, R.; Palomo, M.; Romero, L.; Pérez, P.; Alvarado, M.; Salamanca, F.; Fajardo, A. &Mejía, J. Breastfeeding and early infection in the aetiology of childhood leukaemia in Down

ren's Oncology Group. British Journal of Cancer 2004;91(11) 1866-18872

with Down syndrome. Pediatric Blood & Cancer 2005;44(1) 8-12

syndrome. British Journal of Cancer 2009;101(5) 860-864

2010;172(9) 1015-1027

British Journal of Cancer 2008;99(9) 1529-33

190 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Journal of Epidemiology 2008;167(5) 598-606

demiology 2007;165(5) 496–504

**Chapter 9**

**Genetic Markers in the Prognosis of**

M.R. Juárez-Velázquez, C. Salas-Labadía, A. Reyes-León, M.P. Navarrete-Meneses, E.M. Fuentes-Pananá and P. Pérez-Vera

Additional information is available at the end of the chapter

mal residual disease (MRD) analysis) [4–6].

http://dx.doi.org/10.5772/54288

**1. Introduction**

**Childhood Acute Lymphoblastic Leukemia**

Acute leukemia is a broad term used to identify several malignancies of immature hemato‐ poietic cells. Although, variable incidences have been reported between countries, ranging from 46 to 57 cases by million children, it is considered the most common childhood cancer worldwide [1]. Acute lymphoblastic leukemia (ALL) is the most frequent subtype (75%-80% of cases; with the remaining 20-25% being of myeloid origin, AML). In ALL, B cell origin is the most frequently diagnosed (B cell ALL) representing 83%, and T cell ALL comprises 15%

One of the major achievements in cancer therapy has been the increased cure rates for ALL, from 10% in the 60s to 76-86% today, although these favorable numbers are mainly valid for developed countries[4,5]. The improvement in ALL cure rates can be in part attributed to the assessment of conventional prognostic factors and identification of molecular markers associated with a better response to therapy. Suitable risk stratification has permitted a more personalized treatment, selecting patients for receiving standard or intensified therapy, alone or in combination with drugs against ALL specific targets, and together with an en‐ hanced supportive care have contributed to the increase in the event-free survival (EFS) rates[4]. Conventional childhood ALL stratification is based on prognostic factors related to characteristics of the patient (age at diagnosis) and the disease itself white blood cell (WBC) count at diagnosis, immunophenotype of the leukemic cells, presence of known genetic fu‐ sions, numerical abnormalities or abnormal gene expression, and early response to therapy (evaluated by morphological methods or using a more accurate measurement such as mini‐

and reproduction in any medium, provided the original work is properly cited.

© 2013 Juárez-Velázquez et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

[2]. The total of ALL cases represents 30-40% of all types of pediatric cancer[3].

**Chapter 9**

## **Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia**

M.R. Juárez-Velázquez, C. Salas-Labadía, A. Reyes-León, M.P. Navarrete-Meneses, E.M. Fuentes-Pananá and P. Pérez-Vera

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/54288

## **1. Introduction**

Acute leukemia is a broad term used to identify several malignancies of immature hemato‐ poietic cells. Although, variable incidences have been reported between countries, ranging from 46 to 57 cases by million children, it is considered the most common childhood cancer worldwide [1]. Acute lymphoblastic leukemia (ALL) is the most frequent subtype (75%-80% of cases; with the remaining 20-25% being of myeloid origin, AML). In ALL, B cell origin is the most frequently diagnosed (B cell ALL) representing 83%, and T cell ALL comprises 15% [2]. The total of ALL cases represents 30-40% of all types of pediatric cancer[3].

One of the major achievements in cancer therapy has been the increased cure rates for ALL, from 10% in the 60s to 76-86% today, although these favorable numbers are mainly valid for developed countries[4,5]. The improvement in ALL cure rates can be in part attributed to the assessment of conventional prognostic factors and identification of molecular markers associated with a better response to therapy. Suitable risk stratification has permitted a more personalized treatment, selecting patients for receiving standard or intensified therapy, alone or in combination with drugs against ALL specific targets, and together with an en‐ hanced supportive care have contributed to the increase in the event-free survival (EFS) rates[4]. Conventional childhood ALL stratification is based on prognostic factors related to characteristics of the patient (age at diagnosis) and the disease itself white blood cell (WBC) count at diagnosis, immunophenotype of the leukemic cells, presence of known genetic fu‐ sions, numerical abnormalities or abnormal gene expression, and early response to therapy (evaluated by morphological methods or using a more accurate measurement such as mini‐ mal residual disease (MRD) analysis) [4–6].

© 2013 Juárez-Velázquez et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

From a genetic point of view, ALL is one of the best characterized malignancies. Numerical and structural chromosomal abnormalities have been described by cytogenetic methods, flu‐ orescence *in situ* hybridization (FISH), polymerase chain reaction (PCR), and more recently, by next generation sequencing. Chromosomal abnormalities are clonal markers of the ALL blast, since the cytogenetic and molecular analyses have revealed that approximately 75% of ALL-children present these genetic lesions [7,8]. To date, more than 200 genes have been found participating downstream of common ALL translocations [9]; interestingly, a handful of these genes are consistently affected in many subtypes of the disease paving the way to better understand homeostatic lymphopoiesis and the leukemogenic process [10].

## **2. Signaling and transcription factors important in lymphopoiesis and leukemogenesis**

Generation of lymphoid cells is a highly ordered multi-step process that in adult mam‐ mals starts in bone marrow with the differentiation of multipotent hematopoietic stem cells (HSC) (Figure 1A). HSCs start a differentiation pathway in which the capacity to form multiple lineages is gradually lost coinciding with a gain of lineage specific func‐ tions. Thus, HSCs yield multipotent progenitor cells (MPPs) still with myeloid and lym‐ phoid potential, which eventually give rise to lymphoid-primed multipotent progenitor (LMPP) and early lymphoid progenitor (ELP) populations, with a progressive more re‐ strictive lymphoid program. Similarly, ELPs generate early T lineage progenitors (ETP) and common lymphoid progenitors (CLP), and these populations, although still exhibit high plasticity, preferentially give rise *in vivo* to T and B cells, respectively [11,12]. Intrin‐ sic signaling and transcriptional programs shape this differentiation pathway guiding lin‐ eage decisions. When these developmental programs are abnormally activated or repressed, can induce the leukemogenic process.

**Figure 1. Schematic drawing of the early hematopoietic development.** A) HSCs (hematopoietic stem cells), MPPs (multipotent progenitors), LMPPs (lymphoid-primed MPPs), ELPs (early lymphoid progenitors), CLPs (common lym‐ phoid progenitors), ETPs (early T lineage progenitors). Important branch points during lineage decisions are shown with arrows. B) All B- and T-cell stages can be divided according to the main processes guiding development: receptor assembly, tolerance, and activation. Receptor assembly stages (light gray box) in B and T cells are differentiated by the process of VDJ recombination in the heavy (IgH) and light (IgL) chains, which are recombined in the pro-B and pre-B stages, respectively (b and a rearrangement in DN1-3 and DN4 abT cells). B cells only rearrange heavy and light chains, while T cells can follow two different pathways of TCR chains, ab and gd. Intimate contact between immature B /DP T cells and the stromal cells of the bone marrow and thymus allows those receptors capable of recognizing self-antigens to be identified and eliminated through a variety of mechanisms collectively termed "tolerance". Non-self-reactive cells transit to the mature stage where they become functional cells that could be activated and respond to foreign antigens. The nomenclature of each sub-stage in the mouse model is shown in black letters, e.g. A-D for B cells and DN1–4 for T cells; the most common human nomenclature is shown in red letters. The dashed lines separating all stages indicate checkpoints at which signaling from the pre-BCR/TCR and BCR/TCR is required for positive selection and progression along the maturation pathway. The preBCR, preTCR, and mature receptors are also illustrated in their

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

195

Early developmental stages are the ones generally found compromised in human pediatric B and T cell ALL. These stages in B cell ALL are early proB or pre-proB (before heavy-chain recombination), preB-I (after heavy-chain recombination), and preB-II (before light-chain re‐ arrangement) (Figure 1B). These stages are also recognized by the expression of stage specif‐ ic markers, a characteristic that has helped to classify the different types of pediatric ALL. B cells are recognized by the expression of CD19 and CD10, common B cell ALL by the expres‐ sion of the BCR (IgM) either in cytoplasm (preB-I) or membrane (preB-II), and preB-I can also be differentiated from preB-II cells by expression of the enzyme terminal deoxynucleo‐

respective stages. B cell development occurs in bone marrow and T cell development in the thymus.

tidyl transferase (TdT) [10].

B and T cells are characterized by their potential to express receptors with a highly diverse repertoire of specificities: the B and T cell receptors (BCR and TCR). This diverse specificity is given by a recombination process termed VDJ recombination and it is the sequential as‐ sembly and testing of the BCR and TCR what defines the B/T development pathway. The first stages (pro and pre) are characterized by recombination of the antigen binding variable sequences (heavy and light chains for the BCR, and the β, α, γ or δ chains for the TCR) (Figure 1B). The subsequent stages require elimination of auto-reactive clones, and only clones selected against self-recognition become functional mature cells. Genetic and bio‐ chemical studies have shown that all forms of the BCR and TCR are required for progres‐ sion through several defined developmental checkpoints [13,14]. This is an important concept, since it illustrates that different signaling and transcription programs are operating through all developmental stages, and therefore, if an aberrant program is established, de‐ velopment is unable to proceed. As we will see in the following sections, the leukemic gene fusions and other genetic abnormalities produce aberrant signaling pathways or abnormal transcriptional activities, leading to a developmental arrest in specific stages, events that seem to be required and characterize B and T cell ALL.

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia http://dx.doi.org/10.5772/54288 195

From a genetic point of view, ALL is one of the best characterized malignancies. Numerical and structural chromosomal abnormalities have been described by cytogenetic methods, flu‐ orescence *in situ* hybridization (FISH), polymerase chain reaction (PCR), and more recently, by next generation sequencing. Chromosomal abnormalities are clonal markers of the ALL blast, since the cytogenetic and molecular analyses have revealed that approximately 75% of ALL-children present these genetic lesions [7,8]. To date, more than 200 genes have been found participating downstream of common ALL translocations [9]; interestingly, a handful of these genes are consistently affected in many subtypes of the disease paving the way to

better understand homeostatic lymphopoiesis and the leukemogenic process [10].

194 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

**leukemogenesis**

repressed, can induce the leukemogenic process.

seem to be required and characterize B and T cell ALL.

**2. Signaling and transcription factors important in lymphopoiesis and**

Generation of lymphoid cells is a highly ordered multi-step process that in adult mam‐ mals starts in bone marrow with the differentiation of multipotent hematopoietic stem cells (HSC) (Figure 1A). HSCs start a differentiation pathway in which the capacity to form multiple lineages is gradually lost coinciding with a gain of lineage specific func‐ tions. Thus, HSCs yield multipotent progenitor cells (MPPs) still with myeloid and lym‐ phoid potential, which eventually give rise to lymphoid-primed multipotent progenitor (LMPP) and early lymphoid progenitor (ELP) populations, with a progressive more re‐ strictive lymphoid program. Similarly, ELPs generate early T lineage progenitors (ETP) and common lymphoid progenitors (CLP), and these populations, although still exhibit high plasticity, preferentially give rise *in vivo* to T and B cells, respectively [11,12]. Intrin‐ sic signaling and transcriptional programs shape this differentiation pathway guiding lin‐ eage decisions. When these developmental programs are abnormally activated or

B and T cells are characterized by their potential to express receptors with a highly diverse repertoire of specificities: the B and T cell receptors (BCR and TCR). This diverse specificity is given by a recombination process termed VDJ recombination and it is the sequential as‐ sembly and testing of the BCR and TCR what defines the B/T development pathway. The first stages (pro and pre) are characterized by recombination of the antigen binding variable sequences (heavy and light chains for the BCR, and the β, α, γ or δ chains for the TCR) (Figure 1B). The subsequent stages require elimination of auto-reactive clones, and only clones selected against self-recognition become functional mature cells. Genetic and bio‐ chemical studies have shown that all forms of the BCR and TCR are required for progres‐ sion through several defined developmental checkpoints [13,14]. This is an important concept, since it illustrates that different signaling and transcription programs are operating through all developmental stages, and therefore, if an aberrant program is established, de‐ velopment is unable to proceed. As we will see in the following sections, the leukemic gene fusions and other genetic abnormalities produce aberrant signaling pathways or abnormal transcriptional activities, leading to a developmental arrest in specific stages, events that

**Figure 1. Schematic drawing of the early hematopoietic development.** A) HSCs (hematopoietic stem cells), MPPs (multipotent progenitors), LMPPs (lymphoid-primed MPPs), ELPs (early lymphoid progenitors), CLPs (common lym‐ phoid progenitors), ETPs (early T lineage progenitors). Important branch points during lineage decisions are shown with arrows. B) All B- and T-cell stages can be divided according to the main processes guiding development: receptor assembly, tolerance, and activation. Receptor assembly stages (light gray box) in B and T cells are differentiated by the process of VDJ recombination in the heavy (IgH) and light (IgL) chains, which are recombined in the pro-B and pre-B stages, respectively (b and a rearrangement in DN1-3 and DN4 abT cells). B cells only rearrange heavy and light chains, while T cells can follow two different pathways of TCR chains, ab and gd. Intimate contact between immature B /DP T cells and the stromal cells of the bone marrow and thymus allows those receptors capable of recognizing self-antigens to be identified and eliminated through a variety of mechanisms collectively termed "tolerance". Non-self-reactive cells transit to the mature stage where they become functional cells that could be activated and respond to foreign antigens. The nomenclature of each sub-stage in the mouse model is shown in black letters, e.g. A-D for B cells and DN1–4 for T cells; the most common human nomenclature is shown in red letters. The dashed lines separating all stages indicate checkpoints at which signaling from the pre-BCR/TCR and BCR/TCR is required for positive selection and progression along the maturation pathway. The preBCR, preTCR, and mature receptors are also illustrated in their respective stages. B cell development occurs in bone marrow and T cell development in the thymus.

Early developmental stages are the ones generally found compromised in human pediatric B and T cell ALL. These stages in B cell ALL are early proB or pre-proB (before heavy-chain recombination), preB-I (after heavy-chain recombination), and preB-II (before light-chain re‐ arrangement) (Figure 1B). These stages are also recognized by the expression of stage specif‐ ic markers, a characteristic that has helped to classify the different types of pediatric ALL. B cells are recognized by the expression of CD19 and CD10, common B cell ALL by the expres‐ sion of the BCR (IgM) either in cytoplasm (preB-I) or membrane (preB-II), and preB-I can also be differentiated from preB-II cells by expression of the enzyme terminal deoxynucleo‐ tidyl transferase (TdT) [10].

T cells are recognized by the expression of CD3, CD5 and CD7. Early T cells lack expression of CD4 and CD8 (double negative or DN stages). Contrary to B cell ALL, T cell ALL clones often express markers of more advanced stages of development (for instance double posi‐ tive stages). However, these clones also show a lack of expression or cytoplasmic TCRβ, in‐ dicating that transformation happened before rearrangement of this TCR component or just after, and thus arguing that transformation targeted ETP/DN1 or DN3´cells [15]. The acquis‐ ition of markers of more mature cells is probably due to marker aberrant expression or leu‐ kemia-induced developmental progression in absence of the TCR signal. Although, postnatal B cell early maturation only happens in bone marrow, T cells mature in thymus. LMPP, ELP, CLP and ETP cells are all able to leave bone marrow in response to environ‐ mental signals and complete the T cell maturation program in thymus. Therefore, ETP/DN1 cells are normal residents of bone marrow, while double positive T cells are only found in thymus. T cell transformation of very early populations also agrees with the predominant presence of the T cell leukemic clone in bone marrow [15].

ADAM family of metalloproteinases and the second by the γ−secretase complex. This cleav‐ age activates NOTCH1 removing the extracellular portion and translocating to the nucleus its intracellular region (ICN), where it becomes part of a large transcriptional activation complex together with CSL and histone acetylase p300. Also, ICN has a C-terminal PEST do‐ main involved in regulation of NOTCH1 ubiquitylation and proteasome-mediated degrada‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

197

**Figure 2. Schematic drawing of homeostatic and leukemic expression of acute leukemia inducing genes.** Nor‐ mal (in blue) and leukemic (in red) expression of receptors, signaling proteins and transcription factors is shown along the B and T cell development pathways. Homeostatic factors are shown to the left of the figure and their most com‐ mon modified forms in ALL are shown to the right; the upper part showing the ones compromised in T cells and the bottom part in B cells. Developmental stages are indicated starting with the hematopoietic stem cell (HSC) and then with the early lymphoid progenitor (ELP) and the common lymphoid progenitor (CLP) and further into the T and B cell pathways. Of note, the proB and preB stages are the ones usually compromised in B cell ALL; in T cell ALL, marker expression is indicative of double positive stages but TCR recombination status shows that leukemic stages most prob‐ ably belong to double negative stages. Therefore, the red line representing abnormal leukemic expression extends from DN to DP stages in T cell development. Also, several of the transcription factors compromised in T cell ALL are not

NOTCH1 expression is importantly regulated by E2A [39], and is essential for activation of genes necessary for T cell entry and early development. Indeed, NOTCH1 expression is turned off in late stages of T cell development, forced expression of NOTCH1 in multipotent progenitor cells direct them to the T cell lineage and controls the expression of several tran‐ scription factors important for T cell early development, e.g. *HES1, Bcl11b, GATA3, TCF1, Pu1* and *RUNX1*, among many more [38]. Many of these genes are required to turn off tran‐

normally expressed in these stages but ectopically expressed through the inducing genomic lesion.

tion, therefore controlling protein turnover [35–38].

Limitation of lineage choice during development is regulated by a combination of signaling pathways and transcription factors. The main receptor controlling the proB stage is the IL-7R, which is composed of an α chain (IL-7Rα) and the common cytokine receptor G chain (GC) [16,17]. Deletion of IL-7Rα or GC leads to developmental arrest at the early proB stage [18–21]. IL-7 activates three major signaling pathways: 1) JAK–STAT, 2) phosphatidylinosi‐ tol 3-kinase (PI3K)–Akt and 3) Ras-Raf-Erk [22]. STAT5 (signal transducer and activator of transcription 5) is the predominant STAT protein activated by IL-7 [22,23] and STAT5 loss also arrest B cells at the early proB stage. Once the preBCR is expressed, it can take over many of the functions performed by the IL-7 receptor, since the preBCR also activates the PI3K-Akt and Ras-Raf-Erk pathways [24,25].

Downstream of IL-7 two transcription factors have been documented as the most important for cell entry into the B cell lineage: E2A/TCF3 (immunoglobulin enhancer binding factors E12/E47/transcription factor 3) and EBF1 (Early B cell Factor 1) [26–28]. On the other hand, PAX5 (Paired box 5) is the more important transcription factor for B cell commitment. Loss of E2A and EBF1 blocks entry into the B cell lineage, and loss of PAX5 redirects B cells into other lineages [28–30]. One of the main molecular functions of PAX5 (acting together with E2A, EBF1 and STAT5) is to allow VDJ recombination [31,32]. Ectopic expression of PAX5 and E2A allows VDJ recombination in non-B cells [45, 46]. Also, E2A, PAX5, IKZF1 and RUNX1, among other transcription factors, are responsible for expression of the VDJ recom‐ binase (RAG) [33,34].

The most important cells that give rise to T cells are ELPs and CLPs. Although, both B and T cells are mainly originated from them, an important genetic difference between cells prone to the B lineage is the expression of EBF1 and PAX5, while for T cells is NOTCH1 signaling. NOTCH1 directs progenitors into the thymus and it is the master orchestrator of T cell line‐ age entry and development [35,36]. NOTCH contains multiple epidermal growth factor (EGF)-like repeats through which it binds its ligands DLL-1, -2, -4 (Delta-like ligand), and Jagged-1 and -2 expressed by bone marrow and thymus stromal cells. Upon ligand binding NOTCH1 initiates a series of proteolytic cleavage events, the first one catalyzed by the ADAM family of metalloproteinases and the second by the γ−secretase complex. This cleav‐ age activates NOTCH1 removing the extracellular portion and translocating to the nucleus its intracellular region (ICN), where it becomes part of a large transcriptional activation complex together with CSL and histone acetylase p300. Also, ICN has a C-terminal PEST do‐ main involved in regulation of NOTCH1 ubiquitylation and proteasome-mediated degrada‐ tion, therefore controlling protein turnover [35–38].

T cells are recognized by the expression of CD3, CD5 and CD7. Early T cells lack expression of CD4 and CD8 (double negative or DN stages). Contrary to B cell ALL, T cell ALL clones often express markers of more advanced stages of development (for instance double posi‐ tive stages). However, these clones also show a lack of expression or cytoplasmic TCRβ, in‐ dicating that transformation happened before rearrangement of this TCR component or just after, and thus arguing that transformation targeted ETP/DN1 or DN3´cells [15]. The acquis‐ ition of markers of more mature cells is probably due to marker aberrant expression or leu‐ kemia-induced developmental progression in absence of the TCR signal. Although, postnatal B cell early maturation only happens in bone marrow, T cells mature in thymus. LMPP, ELP, CLP and ETP cells are all able to leave bone marrow in response to environ‐ mental signals and complete the T cell maturation program in thymus. Therefore, ETP/DN1 cells are normal residents of bone marrow, while double positive T cells are only found in thymus. T cell transformation of very early populations also agrees with the predominant

Limitation of lineage choice during development is regulated by a combination of signaling pathways and transcription factors. The main receptor controlling the proB stage is the IL-7R, which is composed of an α chain (IL-7Rα) and the common cytokine receptor G chain (GC) [16,17]. Deletion of IL-7Rα or GC leads to developmental arrest at the early proB stage [18–21]. IL-7 activates three major signaling pathways: 1) JAK–STAT, 2) phosphatidylinosi‐ tol 3-kinase (PI3K)–Akt and 3) Ras-Raf-Erk [22]. STAT5 (signal transducer and activator of transcription 5) is the predominant STAT protein activated by IL-7 [22,23] and STAT5 loss also arrest B cells at the early proB stage. Once the preBCR is expressed, it can take over many of the functions performed by the IL-7 receptor, since the preBCR also activates the

Downstream of IL-7 two transcription factors have been documented as the most important for cell entry into the B cell lineage: E2A/TCF3 (immunoglobulin enhancer binding factors E12/E47/transcription factor 3) and EBF1 (Early B cell Factor 1) [26–28]. On the other hand, PAX5 (Paired box 5) is the more important transcription factor for B cell commitment. Loss of E2A and EBF1 blocks entry into the B cell lineage, and loss of PAX5 redirects B cells into other lineages [28–30]. One of the main molecular functions of PAX5 (acting together with E2A, EBF1 and STAT5) is to allow VDJ recombination [31,32]. Ectopic expression of PAX5 and E2A allows VDJ recombination in non-B cells [45, 46]. Also, E2A, PAX5, IKZF1 and RUNX1, among other transcription factors, are responsible for expression of the VDJ recom‐

The most important cells that give rise to T cells are ELPs and CLPs. Although, both B and T cells are mainly originated from them, an important genetic difference between cells prone to the B lineage is the expression of EBF1 and PAX5, while for T cells is NOTCH1 signaling. NOTCH1 directs progenitors into the thymus and it is the master orchestrator of T cell line‐ age entry and development [35,36]. NOTCH contains multiple epidermal growth factor (EGF)-like repeats through which it binds its ligands DLL-1, -2, -4 (Delta-like ligand), and Jagged-1 and -2 expressed by bone marrow and thymus stromal cells. Upon ligand binding NOTCH1 initiates a series of proteolytic cleavage events, the first one catalyzed by the

presence of the T cell leukemic clone in bone marrow [15].

196 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

PI3K-Akt and Ras-Raf-Erk pathways [24,25].

binase (RAG) [33,34].

**Figure 2. Schematic drawing of homeostatic and leukemic expression of acute leukemia inducing genes.** Nor‐ mal (in blue) and leukemic (in red) expression of receptors, signaling proteins and transcription factors is shown along the B and T cell development pathways. Homeostatic factors are shown to the left of the figure and their most com‐ mon modified forms in ALL are shown to the right; the upper part showing the ones compromised in T cells and the bottom part in B cells. Developmental stages are indicated starting with the hematopoietic stem cell (HSC) and then with the early lymphoid progenitor (ELP) and the common lymphoid progenitor (CLP) and further into the T and B cell pathways. Of note, the proB and preB stages are the ones usually compromised in B cell ALL; in T cell ALL, marker expression is indicative of double positive stages but TCR recombination status shows that leukemic stages most prob‐ ably belong to double negative stages. Therefore, the red line representing abnormal leukemic expression extends from DN to DP stages in T cell development. Also, several of the transcription factors compromised in T cell ALL are not normally expressed in these stages but ectopically expressed through the inducing genomic lesion.

NOTCH1 expression is importantly regulated by E2A [39], and is essential for activation of genes necessary for T cell entry and early development. Indeed, NOTCH1 expression is turned off in late stages of T cell development, forced expression of NOTCH1 in multipotent progenitor cells direct them to the T cell lineage and controls the expression of several tran‐ scription factors important for T cell early development, e.g. *HES1, Bcl11b, GATA3, TCF1, Pu1* and *RUNX1*, among many more [38]. Many of these genes are required to turn off tran‐ scriptional programs of multipotent progenitor cells or other hematopoietic lineages, or for T cell specific functions such as recombinase expression or TCR recombination.

This pharmacological response depends on numerous variables, including drug sensitivity / resistance of the leukemic cells, the dosage and the ability of individual patients to metabo‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

199

The Berlin-Frankfurt Munster (BFM) group has traditionally employed the response to pre‐ dnisone for 7 days and one dose of intrathecal methotrexate to stratify patients. Peripheral blood blast count of 1,000/μl after prednisone treatment is used as a threshold to assign pa‐ tients into two groups, prednisone good responders (GR) and poor responders (PR). The ALL-BMF Group demonstrated in large series of infant patients treated with effective riskbased ALL therapy that prednisone response is a strong prognostic parameter for outcome; 75% of infants were good responders (GR) and achieved an EFS of 53% at 6 years using con‐ ventional therapy, whereas poor responder infants had an EFS of 15% [41]. The Tokyo Can‐ cer Children´s Leukemia Group also showed that B and T cell ALL patients with high blast counts at day 8, had a 4 years EFS of 74%; in contrast, patients without blasts presented an EFS of 89% for B and 95% for T cell ALL [43]. Thus, it is well accepted that early response to prednisone treatment is a strong indicator of EFS [41]. However, this assessment is limited by the low sensitivity (5-10% blasts) of microscopy-based methods of blast quantification [45]. The morphological analysis of blasts by conventional methods easily underestimates the presence and frequency of residual cells. PCR or flow cytometry- based methods for de‐

The common principle for all MRD assessments is that leukemogenic process results in mo‐ lecular and cellular changes, which distinguish leukemic cells from their normal counter‐ parts [46]. In patients with ALL, MRD can be monitored by flow cytometry, PCR amplification of gene fusion transcripts, and PCR amplification of the B and T cell antigen receptors (BCR/TCR specific VDJ recombinants). Combining information about cell size, granularity and expression of surface and intracellular molecules, it is possible to identify by flow cytometry a phenotypic signature characteristic of leukemic cells. Flow cytometrybased identification of cell immunophenotypes allows the detection of one leukemic cell among 10,000 normal cells (0.01%) [47,48]; however, these assays require high expertise for quality results, previous knowledge of immunophenotypic profiles of normal and leukemic cells and experience to select the best markers useful for each patient [49]. Other option to distinguish leukemic from normal cells is the PCR screening of gene fusion transcripts, pro‐ duced by specific chromosomal translocations, among the most common of them are: *BCR-ABL1, MLL-AF4, E2A-PBX1* and *ETV6-RUNX1* [50]. These genetic abnormalities can be detected by PCR with high sensitivities ranging from 0.1- 0.001% [51]. Clonal rearrange‐ ments of the BCR and TCR genes are also useful tools for detecting MRD. Specific VDJ rear‐ rangements result in unique molecular signatures that can be detected by real-time quantitative PCR, with a sensitivity of 0.01-0.001% [52]. The applicability of this latter meth‐ od is useful in 90% of cases, however, a leukemic blast can be associated with more than one VDJ rearrangement during disease progression; for this reason, it is recommended to use at

MRD studies revealed that many patients who achieve remission by traditional methods harbored residual disease predisposing them to relapse [46,48]. The most immediate ap‐

lize and eliminate anti-leukemic drugs [43,44].

tecting MRD are at least 100 times more sensitive.

least two different rearrangements as a target for each patient [53].

Some of the transcription factors drivers of T cell ALL are normally expressed in non-malig‐ nant thymocytes since they are essential regulators of T-cell ontogeny, while others are not expressed in normal ones, but they are rather ectopically expressed by transformed cells (Figure 2). This is contrary to B cells, in which most of the transcription factors associated with transformation fulfill an important regulatory function (Figure 2). This observation supports different mechanisms for the origin of B and T cell ALL. In agreement, *TLX1, TLX3, TAL1, LMO1* and *LMO2* gene loci remain open during TCR recombination, increasing the probability of aberrant rearrangements [39,40]. The identification of the signaling pro‐ teins and transcription factors compromised in B and T cell ALL has helped us to under‐ stand normal B and T cell development and its oncogenic counterpart, and as we will emphasize in the following sections, they have also provided an important tool to classify patients with specific genetic characteristics into risk groups matching disease prognosis.

## **3. Criteria for ALL risk stratification**

The clinical and laboratory criteria supporting risk stratification vary among institutions, with most groups considering as high risk the following characteristics: age ≥ 10 or <1 years at presentation, WBC ≥ 50,000/μl, presence of extramedullary disease, T cell immunopheno‐ type, presence of adverse genetic abnormalities such as t(9;22) (*BCR-ABL1*), *MLL* gene rear‐ rangements, hypodiploidy <44 chromosomes and near haploidy. Finally, a poor response to therapy resulting in ≥ 5% bone marrow blasts at days 15, 19, 29, 35 or 43 post-treatment is also considered of bad prognosis [6].

All the above-mentioned prognostic factors are used to classify patients into two risk groups, high and standard risk. For instance, it is known that increased WBC count confers poor prognosis for B cell ALL patients and in T cell ALL, a leukocyte count greater than 100,000/μl is associated with high risk of relapse in the central nervous system. Also, pa‐ tients with hyperleukocytosis, greater than 400,000/μl, are at high risk of central nervous system hemorrhage and pulmonary and neurological events due to leukostasis. However, most of these risk criteria are better understood for B cell and they are not as clear for T cell ALL patients [3]. Recently, evaluation of early response to therapy has been demonstrated being an important parameter for treatment efficacy and disease prognosis. Based on the lat‐ ter criteria, it is possible to identify the group of patients that require augmented therapy to improve their outcome.

#### **3.1. Prognostic significance of treatment response**

The frequency of bone marrow or circulating lymphoblasts after one week of chemotherapy is associated with risk for relapse [41] and nowadays, this constitutes one of the most useful prognostic factors in childhood ALL. An efficient early response to treatment is determined by evaluating clearance rates of leukemic cells after the induction phase of treatment [42]. This pharmacological response depends on numerous variables, including drug sensitivity / resistance of the leukemic cells, the dosage and the ability of individual patients to metabo‐ lize and eliminate anti-leukemic drugs [43,44].

scriptional programs of multipotent progenitor cells or other hematopoietic lineages, or for

Some of the transcription factors drivers of T cell ALL are normally expressed in non-malig‐ nant thymocytes since they are essential regulators of T-cell ontogeny, while others are not expressed in normal ones, but they are rather ectopically expressed by transformed cells (Figure 2). This is contrary to B cells, in which most of the transcription factors associated with transformation fulfill an important regulatory function (Figure 2). This observation supports different mechanisms for the origin of B and T cell ALL. In agreement, *TLX1, TLX3, TAL1, LMO1* and *LMO2* gene loci remain open during TCR recombination, increasing the probability of aberrant rearrangements [39,40]. The identification of the signaling pro‐ teins and transcription factors compromised in B and T cell ALL has helped us to under‐ stand normal B and T cell development and its oncogenic counterpart, and as we will emphasize in the following sections, they have also provided an important tool to classify patients with specific genetic characteristics into risk groups matching disease prognosis.

The clinical and laboratory criteria supporting risk stratification vary among institutions, with most groups considering as high risk the following characteristics: age ≥ 10 or <1 years at presentation, WBC ≥ 50,000/μl, presence of extramedullary disease, T cell immunopheno‐ type, presence of adverse genetic abnormalities such as t(9;22) (*BCR-ABL1*), *MLL* gene rear‐ rangements, hypodiploidy <44 chromosomes and near haploidy. Finally, a poor response to therapy resulting in ≥ 5% bone marrow blasts at days 15, 19, 29, 35 or 43 post-treatment is

All the above-mentioned prognostic factors are used to classify patients into two risk groups, high and standard risk. For instance, it is known that increased WBC count confers poor prognosis for B cell ALL patients and in T cell ALL, a leukocyte count greater than 100,000/μl is associated with high risk of relapse in the central nervous system. Also, pa‐ tients with hyperleukocytosis, greater than 400,000/μl, are at high risk of central nervous system hemorrhage and pulmonary and neurological events due to leukostasis. However, most of these risk criteria are better understood for B cell and they are not as clear for T cell ALL patients [3]. Recently, evaluation of early response to therapy has been demonstrated being an important parameter for treatment efficacy and disease prognosis. Based on the lat‐ ter criteria, it is possible to identify the group of patients that require augmented therapy to

The frequency of bone marrow or circulating lymphoblasts after one week of chemotherapy is associated with risk for relapse [41] and nowadays, this constitutes one of the most useful prognostic factors in childhood ALL. An efficient early response to treatment is determined by evaluating clearance rates of leukemic cells after the induction phase of treatment [42].

T cell specific functions such as recombinase expression or TCR recombination.

198 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

**3. Criteria for ALL risk stratification**

also considered of bad prognosis [6].

improve their outcome.

**3.1. Prognostic significance of treatment response**

The Berlin-Frankfurt Munster (BFM) group has traditionally employed the response to pre‐ dnisone for 7 days and one dose of intrathecal methotrexate to stratify patients. Peripheral blood blast count of 1,000/μl after prednisone treatment is used as a threshold to assign pa‐ tients into two groups, prednisone good responders (GR) and poor responders (PR). The ALL-BMF Group demonstrated in large series of infant patients treated with effective riskbased ALL therapy that prednisone response is a strong prognostic parameter for outcome; 75% of infants were good responders (GR) and achieved an EFS of 53% at 6 years using con‐ ventional therapy, whereas poor responder infants had an EFS of 15% [41]. The Tokyo Can‐ cer Children´s Leukemia Group also showed that B and T cell ALL patients with high blast counts at day 8, had a 4 years EFS of 74%; in contrast, patients without blasts presented an EFS of 89% for B and 95% for T cell ALL [43]. Thus, it is well accepted that early response to prednisone treatment is a strong indicator of EFS [41]. However, this assessment is limited by the low sensitivity (5-10% blasts) of microscopy-based methods of blast quantification [45]. The morphological analysis of blasts by conventional methods easily underestimates the presence and frequency of residual cells. PCR or flow cytometry- based methods for de‐ tecting MRD are at least 100 times more sensitive.

The common principle for all MRD assessments is that leukemogenic process results in mo‐ lecular and cellular changes, which distinguish leukemic cells from their normal counter‐ parts [46]. In patients with ALL, MRD can be monitored by flow cytometry, PCR amplification of gene fusion transcripts, and PCR amplification of the B and T cell antigen receptors (BCR/TCR specific VDJ recombinants). Combining information about cell size, granularity and expression of surface and intracellular molecules, it is possible to identify by flow cytometry a phenotypic signature characteristic of leukemic cells. Flow cytometrybased identification of cell immunophenotypes allows the detection of one leukemic cell among 10,000 normal cells (0.01%) [47,48]; however, these assays require high expertise for quality results, previous knowledge of immunophenotypic profiles of normal and leukemic cells and experience to select the best markers useful for each patient [49]. Other option to distinguish leukemic from normal cells is the PCR screening of gene fusion transcripts, pro‐ duced by specific chromosomal translocations, among the most common of them are: *BCR-ABL1, MLL-AF4, E2A-PBX1* and *ETV6-RUNX1* [50]. These genetic abnormalities can be detected by PCR with high sensitivities ranging from 0.1- 0.001% [51]. Clonal rearrange‐ ments of the BCR and TCR genes are also useful tools for detecting MRD. Specific VDJ rear‐ rangements result in unique molecular signatures that can be detected by real-time quantitative PCR, with a sensitivity of 0.01-0.001% [52]. The applicability of this latter meth‐ od is useful in 90% of cases, however, a leukemic blast can be associated with more than one VDJ rearrangement during disease progression; for this reason, it is recommended to use at least two different rearrangements as a target for each patient [53].

MRD studies revealed that many patients who achieve remission by traditional methods harbored residual disease predisposing them to relapse [46,48]. The most immediate ap‐ plication of MRD testing is the identification of patients who are candidates for treat‐ ment intensification, since levels of MRD are proportional to the risk of relapse [51]. The most appropriate time for evaluation of MRD vary between different groups, for the ALL-BMF 95 protocol in Austria, MRD quantification by flow cytometry of bone marrow samples must be estimated on days 33 and 78 post-treatment. In the experience of St. Jude Children's Research Hospital, the presence of 0.01% residual cells on days 19, 46, or subsequent time points during treatment, is strongly associated with a high risk of re‐ lapse [54,55]. The Children's Oncology Group quantifies MRD in bone marrow on day 29 post-treatment, and ≥ 0.01% of MRD is associated with poor outcome [56]. The Dana-Farber Cancer Institute ALL Consortium, considers MRD cut-off values of 0.1% for pre‐ diction of 5-year relapse hazard [57]. Recently, the Italian cooperative group AIEOP identified 3 risk groups based on MRD values by flow cytometry of bone marrow sam‐ ples on day 15 of treatment. Those risk groups are: standard (<0.01% MRD) with a 5 years cumulative incidence of relapse (CIR) of 7.5%, intermediate (0.01% - <10% MRD) with CIR of 17.5%, and high (>10% MRD) with CIR of 47.2% [58]. MRD is also useful as an independent predictor of second relapse in patients with ALL who had a previous re‐ lapse and achieved a second remission [59,60]. Notably, the time of first relapse and MRD are the only 2 significant predictors of outcome in a multivariate analysis [60].

abnormality, hyperdiploidy, in 100% of patients in one study [9]. However, it is accepted that for all mentioned cases this first oncogenic hit is not sufficient, and additional postnatal

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

201

The known ALL genetic abnormalities have been relevant for the identification of genes in‐ volved in cancer and therefore for the insights in the biology of the leukemogenic process. Importantly, these genetic abnormalities are a disease signature that has been an invaluable tool for the precise disease diagnosis, prognosis and stratification into risk groups, guiding patient management and treatment choice [63]. The Third International Workshop on Chro‐ mosomes in Leukemia was the first major study demonstrating the independent prognostic significance of cytogenetic findings in ALL, providing data on clinical relevance of chromo‐ somal recurrent aberrations, and elucidating its molecular basis and biologic consequences [64]. Given their importance, it is the main goal of this chapter to describe in detail the most important genetic abnormalities in the stratification of ALL patients, highlighting aspects of

mutational events are required for disease initiation [62].

their oncogenic mechanisms, incidence and prognosis.

of them will be discussed in the coming sections.

**4.1.** *BCR-ABL1* **fusion**

**4. Molecular and cytogenetic subgroups in pediatric B cell ALL**

As it was previously mentioned, several genetic abnormalities are characteristic of ALL and have been relevant for the identification of genes involved in cancer and therefore have giv‐ en insights into the biology of the leukemogenic process, plus they have been an invaluable tool for the precise disease diagnosis, prognosis and stratification into risk groups. Several

The *BCR-ABL1* fusion is generated by a reciprocal translocation between sequences of the *BCR* (Breakpoint cluster region; do not confuse with the B cell receptor) gene located at 22q11.23, and the *ABL1* (Abelson tyrosine-protein kinase 1) gene located at 9q34.1. This translocation generates a derivative chromosome 22 known as the Philadelphia (Ph) chro‐ mosome, and was first observed in adult patients with chronic myeloid leukemia (CML), but later also in approximately 3-5% of pediatric ALL patients. The *BCR* gene contains 23 exons and encodes a 160 kD phosphoprotein of still unclear function. However, its first exon, which is normally present in the BCR-ABL1 protein, contains a serine/threonine kin‐ ase activity and SH2 binding sites [65]. On the other hand, *ABL1* is a proto-oncogene that encodes a cytoplasmic and nuclear protein tyrosine kinase implicated in cell differentiation, cell division, cell adhesion, and stress response [66,67]. The *BCR-ABL1* fusion produces a chimeric protein with cytoplasmic localization and oncogenic potential because retains the catalytic domain of ABL1 fused to the BCR domain, which mediates constitutive oligomeri‐ zation of the fusion protein in the absence of physiologic activating signals, thereby promot‐ ing aberrant tyrosine kinase constitutive activity, inducing aberrant signaling and activating multiple cellular pathways [3,68–70]. Among the signaling pathways activated contributing

#### **3.2. Genetic abnormalities in ALL as prognostic factors**

From a genetic point of view, ALL is one of the best characterized malignancies. Numerical and structural chromosomal abnormalities have been described by cytogenetic methods, FISH, PCR, and more recently, by next generation sequencing. Chromosomal abnormalities are clonal markers of the ALL blast, since the cytogenetic and molecular analyses have re‐ vealed that approximately 75% of ALL-children present these genetic lesions [7]. To date, more than 200 genes have been found participating, downstream of common ALL transloca‐ tions. Interestingly, a handful of these genes are affected by more than one translocation, thus supporting specific mechanisms of leukemogenesis [9].

The genetic abnormalities found in ALL are basically of two types: 1) gains or losses of one or several chromosomes (numerical abnormalities) and 2) translocations generating gene fu‐ sions that encode proteins with novel functions (chimeric proteins), or that re-locate a gene close to a strong transcriptional promoter causing gene overexpression. These translocations are produced by double-strand breaks (DSB) in different chromosomes or different regions of one chromosome, that are then recombined through non-homologous end-joining mecha‐ nisms [9,61]. These events of illegitimate recombination result in juxtaposition of normally separated regions, relocating a gene or producing a chimeric fusion gene [3].

Several studies have demonstrated that the first genetic lesion in childhood ALL often oc‐ curs in uterus. Screening of many of the genetic lesions that characterize the ALL blast in blood samples from Guthrie cards supports their prenatal origin. These studies have shown the presence of the same gene fusion in blood samples collected at birth and in the leukemic blasts at diagnosis. Thus, an intrauterine origin of *MLL-AF4* has been observed in 100% of the studied cases, *ETV6-RUNX1* in 75% of cases, *E2A-PBX1* in 10% of cases and a numerical abnormality, hyperdiploidy, in 100% of patients in one study [9]. However, it is accepted that for all mentioned cases this first oncogenic hit is not sufficient, and additional postnatal mutational events are required for disease initiation [62].

The known ALL genetic abnormalities have been relevant for the identification of genes in‐ volved in cancer and therefore for the insights in the biology of the leukemogenic process. Importantly, these genetic abnormalities are a disease signature that has been an invaluable tool for the precise disease diagnosis, prognosis and stratification into risk groups, guiding patient management and treatment choice [63]. The Third International Workshop on Chro‐ mosomes in Leukemia was the first major study demonstrating the independent prognostic significance of cytogenetic findings in ALL, providing data on clinical relevance of chromo‐ somal recurrent aberrations, and elucidating its molecular basis and biologic consequences [64]. Given their importance, it is the main goal of this chapter to describe in detail the most important genetic abnormalities in the stratification of ALL patients, highlighting aspects of their oncogenic mechanisms, incidence and prognosis.

## **4. Molecular and cytogenetic subgroups in pediatric B cell ALL**

As it was previously mentioned, several genetic abnormalities are characteristic of ALL and have been relevant for the identification of genes involved in cancer and therefore have giv‐ en insights into the biology of the leukemogenic process, plus they have been an invaluable tool for the precise disease diagnosis, prognosis and stratification into risk groups. Several of them will be discussed in the coming sections.

#### **4.1.** *BCR-ABL1* **fusion**

plication of MRD testing is the identification of patients who are candidates for treat‐ ment intensification, since levels of MRD are proportional to the risk of relapse [51]. The most appropriate time for evaluation of MRD vary between different groups, for the ALL-BMF 95 protocol in Austria, MRD quantification by flow cytometry of bone marrow samples must be estimated on days 33 and 78 post-treatment. In the experience of St. Jude Children's Research Hospital, the presence of 0.01% residual cells on days 19, 46, or subsequent time points during treatment, is strongly associated with a high risk of re‐ lapse [54,55]. The Children's Oncology Group quantifies MRD in bone marrow on day 29 post-treatment, and ≥ 0.01% of MRD is associated with poor outcome [56]. The Dana-Farber Cancer Institute ALL Consortium, considers MRD cut-off values of 0.1% for pre‐ diction of 5-year relapse hazard [57]. Recently, the Italian cooperative group AIEOP identified 3 risk groups based on MRD values by flow cytometry of bone marrow sam‐ ples on day 15 of treatment. Those risk groups are: standard (<0.01% MRD) with a 5 years cumulative incidence of relapse (CIR) of 7.5%, intermediate (0.01% - <10% MRD) with CIR of 17.5%, and high (>10% MRD) with CIR of 47.2% [58]. MRD is also useful as an independent predictor of second relapse in patients with ALL who had a previous re‐ lapse and achieved a second remission [59,60]. Notably, the time of first relapse and MRD are the only 2 significant predictors of outcome in a multivariate analysis [60].

200 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

From a genetic point of view, ALL is one of the best characterized malignancies. Numerical and structural chromosomal abnormalities have been described by cytogenetic methods, FISH, PCR, and more recently, by next generation sequencing. Chromosomal abnormalities are clonal markers of the ALL blast, since the cytogenetic and molecular analyses have re‐ vealed that approximately 75% of ALL-children present these genetic lesions [7]. To date, more than 200 genes have been found participating, downstream of common ALL transloca‐ tions. Interestingly, a handful of these genes are affected by more than one translocation,

The genetic abnormalities found in ALL are basically of two types: 1) gains or losses of one or several chromosomes (numerical abnormalities) and 2) translocations generating gene fu‐ sions that encode proteins with novel functions (chimeric proteins), or that re-locate a gene close to a strong transcriptional promoter causing gene overexpression. These translocations are produced by double-strand breaks (DSB) in different chromosomes or different regions of one chromosome, that are then recombined through non-homologous end-joining mecha‐ nisms [9,61]. These events of illegitimate recombination result in juxtaposition of normally

Several studies have demonstrated that the first genetic lesion in childhood ALL often oc‐ curs in uterus. Screening of many of the genetic lesions that characterize the ALL blast in blood samples from Guthrie cards supports their prenatal origin. These studies have shown the presence of the same gene fusion in blood samples collected at birth and in the leukemic blasts at diagnosis. Thus, an intrauterine origin of *MLL-AF4* has been observed in 100% of the studied cases, *ETV6-RUNX1* in 75% of cases, *E2A-PBX1* in 10% of cases and a numerical

separated regions, relocating a gene or producing a chimeric fusion gene [3].

**3.2. Genetic abnormalities in ALL as prognostic factors**

thus supporting specific mechanisms of leukemogenesis [9].

The *BCR-ABL1* fusion is generated by a reciprocal translocation between sequences of the *BCR* (Breakpoint cluster region; do not confuse with the B cell receptor) gene located at 22q11.23, and the *ABL1* (Abelson tyrosine-protein kinase 1) gene located at 9q34.1. This translocation generates a derivative chromosome 22 known as the Philadelphia (Ph) chro‐ mosome, and was first observed in adult patients with chronic myeloid leukemia (CML), but later also in approximately 3-5% of pediatric ALL patients. The *BCR* gene contains 23 exons and encodes a 160 kD phosphoprotein of still unclear function. However, its first exon, which is normally present in the BCR-ABL1 protein, contains a serine/threonine kin‐ ase activity and SH2 binding sites [65]. On the other hand, *ABL1* is a proto-oncogene that encodes a cytoplasmic and nuclear protein tyrosine kinase implicated in cell differentiation, cell division, cell adhesion, and stress response [66,67]. The *BCR-ABL1* fusion produces a chimeric protein with cytoplasmic localization and oncogenic potential because retains the catalytic domain of ABL1 fused to the BCR domain, which mediates constitutive oligomeri‐ zation of the fusion protein in the absence of physiologic activating signals, thereby promot‐ ing aberrant tyrosine kinase constitutive activity, inducing aberrant signaling and activating multiple cellular pathways [3,68–70]. Among the signaling pathways activated contributing to leukemogenesis are JAK2 kinase/STAT5, MAP kinases and PI3K/Akt, which includes sev‐ eral members of the Bcl-2 family of anti-apoptotic proteins.

> **Genetic abnormalities**

**Hyperdiploidy >50 chromosomes**

**Hypodiploidy <44 chromosomes**

**t(1;19)(q23;p13)** *E2A-PBX1*

**11q23 rearrangements** *MLL*

> **t(9;22) (q34;q11.2)** *BCR-ABL1*

**t(12;21) (p13;q22)** *ETV6-RUNX1*


**4.2.** *E2A-PBX1* **fusion**

**UK Medical Research Council ALL97/99 [77]**

**ALL-BFM90 [78,80]**

**UKCCG [81]**

4 2 - 5

**Frequency in different populations (%)**

**Europe America Asia**

**Numerical changes**

38 - 31 25 41 31 - 24 -

**Structural changes**


5 *E2A-PBX1* or *E2A-HLF*

2 3 2 8 2 9 0 3 5

3 2 2 2 1 4 5 17 7

25 22 21 25 13 9 7 19 13

The *E2A-PBX1* fusion results from the balanced translocation t(1;19)(q23;p13) or the unbal‐ anced derivative der(19)t(1;19), that involve *E2A* (previously described as the Immunoglo‐ bulin enhancer binding factors E12/E47, also named *TCF3*) and *PBX1* (Pre-B cell leukemia

**Table 1.** Frequency of numerical and structural changes among B-ALL patients of different cohorts

**Hispanics [83]**

**Mexico [84]**

**India [4]**

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

**China [85]**

5 7 5 4

**Malaysia-Singapore [86]**

http://dx.doi.org/10.5772/54288

**StJChRH [82]**

**Clinical implication** 203

Excellent prognosis with antimetabolite treatment

prognosis

Improved prognosis with highdose methotrexate treatment

> Poor prognosis

Improved early treatment outcome with imatinib

Excellent prognosis with asparaginase

The Ph chromosome detected in CML varies from the one in ALL, with different *BCR* breakpoints between diseases. Two chimeric proteins with different leukemogenic poten‐ tial are encoded, one of 210 kDa prevalent in CML and other of 190 kDa prevalent in childhood ALL [70,71]. *In vitro* studies showed that the 190kDa BCR-ABL exhibits a greater tyrosine kinase activity than the 210kDa form. Thus, this fusion defines one of the subgroups of ALL with the worst clinical prognosis, mainly because it leads to genet‐ ic instability through the reduction in DNA repair fidelity and by generation of reactive oxygen species, that enhance spontaneous DNA damage in tumor cells that can yield the accumulation of additional genetic mutations [72,73].

Ph positive childhood ALL is associated with older age at presentation, high leukocyte count, French-American-British (FAB) L2 morphology, and high incidence of central nervous system. Age at ALL presentation influences the prognosis of this genetic rear‐ rangement; patients with ages ranging from one to nine years have a better prognosis than adolescents and young adults [70,74]. Thus, Ph positive is associated with a very high risk and poor prognosis. Although more than 95% of patients achieve an adequate response to induction therapy, these remissions are shallow and short-lived [6]; addition‐ ally, these patients frequently present high levels of MRD at the end of the induction therapy [75]. Ph positive ALL incidence varies among different cohorts (Table 1), ranging between 2-3% for Western European countries (Germany, Italy, Austria, Britain, Switzer‐ land) [76–78], 1-4% for American countries (USA and Mexico) [4,79] and 7-15% for East‐ ern countries (China, Taiwan, Malaysia-Singapore) [63].

Intensive research efforts were done to demonstrate the BCR-ABL1 transforming activity *in vitro* and *in vivo*, as well as to describe the downstream signaling pathways and tran‐ scriptional programs affected by this translocation. These studies led to the development of successful targeted therapy with small-molecule tyrosine kinase inhibitors (TKI), such as STI571 (Imatinib mesylate, Gleevec®, Novartis Pharmaceuticals, Basel, Switzerland). This TKI has successfully been used for treatment of Ph positive CML patients [69,87] and has also permitted a better management of ALL patients. Remissions have been ach‐ ieved when Imatinib has been used either as single agent or as part of combination regi‐ mens. In accordance with COG ALLL0031 trial (2002-2006), patients who received a regimen that included Imatinib achieved a 3-year EFS of 80%, which was more than the double of the EFS rate of patients treated without this agent. Although the number of treated patients was small in this study, it supported that the addition of Imatinib to in‐ tensive chemotherapy can improve the outcome of Ph positive ALL children [74,87]. Ge‐ nomic studies have identified a subtype of pediatric B cell ALL Ph negative patients with a gene-expression profile similar to *BCR-ABL1* positive ones, it is thought that these "*BCR-ABL1* like" disease harbors mutations that deregulate cytokine receptor and tyro‐ sine kinase signaling, this subset of B cell ALL patients might also be benefited by the TKI therapy [87]. "*BCR-ABL1* like" group will be mentioned in a following section.


**Table 1.** Frequency of numerical and structural changes among B-ALL patients of different cohorts

#### **4.2.** *E2A-PBX1* **fusion**

to leukemogenesis are JAK2 kinase/STAT5, MAP kinases and PI3K/Akt, which includes sev‐

The Ph chromosome detected in CML varies from the one in ALL, with different *BCR* breakpoints between diseases. Two chimeric proteins with different leukemogenic poten‐ tial are encoded, one of 210 kDa prevalent in CML and other of 190 kDa prevalent in childhood ALL [70,71]. *In vitro* studies showed that the 190kDa BCR-ABL exhibits a greater tyrosine kinase activity than the 210kDa form. Thus, this fusion defines one of the subgroups of ALL with the worst clinical prognosis, mainly because it leads to genet‐ ic instability through the reduction in DNA repair fidelity and by generation of reactive oxygen species, that enhance spontaneous DNA damage in tumor cells that can yield the

Ph positive childhood ALL is associated with older age at presentation, high leukocyte count, French-American-British (FAB) L2 morphology, and high incidence of central nervous system. Age at ALL presentation influences the prognosis of this genetic rear‐ rangement; patients with ages ranging from one to nine years have a better prognosis than adolescents and young adults [70,74]. Thus, Ph positive is associated with a very high risk and poor prognosis. Although more than 95% of patients achieve an adequate response to induction therapy, these remissions are shallow and short-lived [6]; addition‐ ally, these patients frequently present high levels of MRD at the end of the induction therapy [75]. Ph positive ALL incidence varies among different cohorts (Table 1), ranging between 2-3% for Western European countries (Germany, Italy, Austria, Britain, Switzer‐ land) [76–78], 1-4% for American countries (USA and Mexico) [4,79] and 7-15% for East‐

Intensive research efforts were done to demonstrate the BCR-ABL1 transforming activity *in vitro* and *in vivo*, as well as to describe the downstream signaling pathways and tran‐ scriptional programs affected by this translocation. These studies led to the development of successful targeted therapy with small-molecule tyrosine kinase inhibitors (TKI), such as STI571 (Imatinib mesylate, Gleevec®, Novartis Pharmaceuticals, Basel, Switzerland). This TKI has successfully been used for treatment of Ph positive CML patients [69,87] and has also permitted a better management of ALL patients. Remissions have been ach‐ ieved when Imatinib has been used either as single agent or as part of combination regi‐ mens. In accordance with COG ALLL0031 trial (2002-2006), patients who received a regimen that included Imatinib achieved a 3-year EFS of 80%, which was more than the double of the EFS rate of patients treated without this agent. Although the number of treated patients was small in this study, it supported that the addition of Imatinib to in‐ tensive chemotherapy can improve the outcome of Ph positive ALL children [74,87]. Ge‐ nomic studies have identified a subtype of pediatric B cell ALL Ph negative patients with a gene-expression profile similar to *BCR-ABL1* positive ones, it is thought that these "*BCR-ABL1* like" disease harbors mutations that deregulate cytokine receptor and tyro‐ sine kinase signaling, this subset of B cell ALL patients might also be benefited by the TKI therapy [87]. "*BCR-ABL1* like" group will be mentioned in a following section.

eral members of the Bcl-2 family of anti-apoptotic proteins.

202 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

accumulation of additional genetic mutations [72,73].

ern countries (China, Taiwan, Malaysia-Singapore) [63].

The *E2A-PBX1* fusion results from the balanced translocation t(1;19)(q23;p13) or the unbal‐ anced derivative der(19)t(1;19), that involve *E2A* (previously described as the Immunoglo‐ bulin enhancer binding factors E12/E47, also named *TCF3*) and *PBX1* (Pre-B cell leukemia transcription factor 1) genes. *E2A* encodes two basic helix-loop-helix (bHLH) transcription factors, E12 and E47, through alternative splicing. Both transcription factors are immunoglo‐ bulin enhancer binding proteins involved in the regulation of immunoglobulin gene expres‐ sion [34] and in the initiation and specification of the B cell lineage [29]. *PBX1* also encodes a transcription factor (Leukemia Homeobox 1), a member of the three amino acid loop exten‐ sion (TALE) family of homeodomain proteins. PBX1 forms heterodimers with HOX family homeodomain proteins and together with them cooperatively regulates transcription of sev‐ eral target genes according to the HOX partner [88,89]. PBX1 regulates the self-renewal po‐ tential of HSC by maintaining their quiescence state; additionally, it modulates early stages of B-cell development. PBX1 is also important for the multi-linage potential of human em‐ bryonic stem cells (hESC) [90].

stroma. One of the important functions regulated by GAS6 is HSC self-renewal and it is pos‐ sible that the leukemic blast becomes resistant to conventional chemotherapy due to GAS6 induced quiescence. Similar to BCR-ABL1 targeted therapy, GAS6-MerTK interaction might

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

205

Another translocation involving the *E2A* gene in ALL is t(17;19)(q22;p13), present in 1% of children, which produces the fusion of *E2A* to *HLF* (Hepatic leukemia factor). *HLF* is a mem‐ ber of the bZIP family of transcription factors and the E2A-HLF fusion protein contains the transcriptional activation domain of E2A linked to the DNA-binding and protein-protein in‐ teraction motifs of HLF. The resulting chimeric protein most probably activates the tran‐ scription of genes normally regulated by HLF. It is suggested that E2A-HLF inhibits apoptosis through the aberrant up-regulation of SLUG and LMO2, which are anti-apoptotic

Myeloid/lymphoid or Mixed lineage leukemia gene (*MLL, MLL1, ALL1, TRX*, and *HTRX*) is the human homologue of the *Drosophila melanogaster* trithorax gene; it is located at 11q23 and consists of 36 exons. It encodes a 430 kDa DNA binding protein that positively regulates *HOX* gene expression through methylation of lysine 4 of histone 3 (H3K4) [101]. MLL is a large multi-domain protein, the N-terminus contains three short AT-hook motifs (ATH 1–3), which are thought to mediate DNA binding. There are two speckled nuclear localization sites (SNL1 and SNL2) immediately C-terminal to the ATH motifs that are followed by a transcriptional repression domain consisting of two functional subunits, RD1 and RD2. RD1 contains a DNA methyltransferase (DMT) homology domain with a CxxC zinc-finger motif that might recruit transcriptional repressors. RD2 recruits histone deacetylases HDAC1 and HDAC2. There is also a plant homology domain (PHD) zinc-finger motif that might mediate protein-protein interactions and a C-terminal SET (Su(var)3-9, enchancer-of-zeste, trithorax) domain that possesses histone H3 lysine 4 (H3K4) methyltransferase activity [95]. Despite RD1 and RD2, MLL is thought to be primarily a transcriptional activator due to its methyl‐ transferase activity and to the transcriptional activation domain, which recruits the tran‐ scriptional co-activator CBP (CREB-binding protein). MLL is thought to be a master gene for

MLL in its mature form consists of two non-covalently associated subunits, an N-terminal 320 kDa fragment (MLLN) and a C-terminal 180 kDa moiety (MLLC), which are both core components of the MLL complex and result from the cleavage of nascent MLL by an aspart‐ ic protease named taspase 1. The MLLN fragment is thought to bind DNA regulatory regions of clustered *HOX* genes as part of a multi-subunit complex that includes components of the basal transcription machinery and mediate transcriptional repression of *HOX* genes. How‐ ever, in the presence of MLLC, the MLLN complex can lead to transcriptional activation. The MLLC subunit contains the SET motif and associates with at least four proteins that modify chromatin for efficient transcription through methylation, acetylation and nucleosome re‐ modeling processes [101,102]. *MLL* gene is ubiquitously expressed in haematopoietic cells including stem and progenitor populations, and *HOX* genes are direct targets of MLL dur‐

be an important target for directed therapy [94].

factors in normal hematopoietic progenitor cells [10,100].

epigenetic transcriptional memory regulation.

**4.3.** *MLL* **translocations**

*E2A-PBX1* fusion results in chimeric proteins that contain the transcriptional activation do‐ main of E2A linked to the DNA-binding domain and HOX heterodimerization domain of PBX1. The resulting oncogenic transcription factor inappropriately activates the expression of genes normally regulated by the PBX1-HOX heterodimers [3,91]. Among the transcrip‐ tional targets of E2A-PBX1 are *WNT16* and *MerTK*. Since the WTN family is widely recog‐ nized to be involved in oncogenesis, it is possible that *E2A-PBX1* initiates the leukemogenic process through its potent expression of WNT16 [10,92]. MerTK is a receptor with a coupled tyrosine kinase activity that regulates self-renewal of bone marrow precursor cells, and al‐ though MerTK is not normally expressed in committed lymphocytes, high level expression is detected in B and T cell ALL and mantle cell lymphomas [93,94].

According to studies in different populations (Table 1), *E2A-PBX1* translocation is present in approximately 2-6% of pediatric ALL cases; however its incidence among the specific pre-B ALL subtype (the one with cytoplasmic or membrane IgM) is approximately 25% [64,95,96]. The Total Therapy Study XIIIB at St Jude Children's Research Hospital reported an inci‐ dence of 4.7%, with 5-year EFS of 80-90% [4,97]. On the other hand, the reported incidences for European countries, such as Great Britain, Germany, Italy, Austria and Switzerland, is between 2.1 and 4%, while the reported incidences for Eastern countries (Malaysia, Singa‐ pore and China) range from 4.12 to 5.37%. *E2A-PBX1* has barely been detected in Guthrie cards of B cell ALL patients, which suggests that in most cases emerges postnatally [9]. Also, the molecular breakpoints of the *E2A-PBX1* fusion in IgM positive or IgM negative cases are generally dissimilar suggesting different origins of the disease [3,98].

Clinical features of pre-B ALL positive for *E2A-PBX1*, include 5 year age at presentation, WBC count of 21-28,000/μl and pseudodiploid karyotypes [64,87,99]. Risk stratification for *E2A/PBX1* patients is controversial. It is considered of poor prognosis in adult cases, while in children it has been reported either relatively favorable or of poor prognosis. This could be explained in part by treatment differences; although it was initially considered of an un‐ favorable outcome, rate cures have been improved with the use of more effective therapies, such as dosage intensification with methotrexate [64,82]. Future treatment improvements could be achieved based on the discovery of pathways for treatment resistance of *E2A-PBX1* positive cells. It has been shown that *MerTK* is activated by GAS6 (Growth arrest specific 6) produced in bone marrow by mesenchymal cells, which are part of the HSC supporting stroma. One of the important functions regulated by GAS6 is HSC self-renewal and it is pos‐ sible that the leukemic blast becomes resistant to conventional chemotherapy due to GAS6 induced quiescence. Similar to BCR-ABL1 targeted therapy, GAS6-MerTK interaction might be an important target for directed therapy [94].

Another translocation involving the *E2A* gene in ALL is t(17;19)(q22;p13), present in 1% of children, which produces the fusion of *E2A* to *HLF* (Hepatic leukemia factor). *HLF* is a mem‐ ber of the bZIP family of transcription factors and the E2A-HLF fusion protein contains the transcriptional activation domain of E2A linked to the DNA-binding and protein-protein in‐ teraction motifs of HLF. The resulting chimeric protein most probably activates the tran‐ scription of genes normally regulated by HLF. It is suggested that E2A-HLF inhibits apoptosis through the aberrant up-regulation of SLUG and LMO2, which are anti-apoptotic factors in normal hematopoietic progenitor cells [10,100].

#### **4.3.** *MLL* **translocations**

transcription factor 1) genes. *E2A* encodes two basic helix-loop-helix (bHLH) transcription factors, E12 and E47, through alternative splicing. Both transcription factors are immunoglo‐ bulin enhancer binding proteins involved in the regulation of immunoglobulin gene expres‐ sion [34] and in the initiation and specification of the B cell lineage [29]. *PBX1* also encodes a transcription factor (Leukemia Homeobox 1), a member of the three amino acid loop exten‐ sion (TALE) family of homeodomain proteins. PBX1 forms heterodimers with HOX family homeodomain proteins and together with them cooperatively regulates transcription of sev‐ eral target genes according to the HOX partner [88,89]. PBX1 regulates the self-renewal po‐ tential of HSC by maintaining their quiescence state; additionally, it modulates early stages of B-cell development. PBX1 is also important for the multi-linage potential of human em‐

*E2A-PBX1* fusion results in chimeric proteins that contain the transcriptional activation do‐ main of E2A linked to the DNA-binding domain and HOX heterodimerization domain of PBX1. The resulting oncogenic transcription factor inappropriately activates the expression of genes normally regulated by the PBX1-HOX heterodimers [3,91]. Among the transcrip‐ tional targets of E2A-PBX1 are *WNT16* and *MerTK*. Since the WTN family is widely recog‐ nized to be involved in oncogenesis, it is possible that *E2A-PBX1* initiates the leukemogenic process through its potent expression of WNT16 [10,92]. MerTK is a receptor with a coupled tyrosine kinase activity that regulates self-renewal of bone marrow precursor cells, and al‐ though MerTK is not normally expressed in committed lymphocytes, high level expression

According to studies in different populations (Table 1), *E2A-PBX1* translocation is present in approximately 2-6% of pediatric ALL cases; however its incidence among the specific pre-B ALL subtype (the one with cytoplasmic or membrane IgM) is approximately 25% [64,95,96]. The Total Therapy Study XIIIB at St Jude Children's Research Hospital reported an inci‐ dence of 4.7%, with 5-year EFS of 80-90% [4,97]. On the other hand, the reported incidences for European countries, such as Great Britain, Germany, Italy, Austria and Switzerland, is between 2.1 and 4%, while the reported incidences for Eastern countries (Malaysia, Singa‐ pore and China) range from 4.12 to 5.37%. *E2A-PBX1* has barely been detected in Guthrie cards of B cell ALL patients, which suggests that in most cases emerges postnatally [9]. Also, the molecular breakpoints of the *E2A-PBX1* fusion in IgM positive or IgM negative cases are

Clinical features of pre-B ALL positive for *E2A-PBX1*, include 5 year age at presentation, WBC count of 21-28,000/μl and pseudodiploid karyotypes [64,87,99]. Risk stratification for *E2A/PBX1* patients is controversial. It is considered of poor prognosis in adult cases, while in children it has been reported either relatively favorable or of poor prognosis. This could be explained in part by treatment differences; although it was initially considered of an un‐ favorable outcome, rate cures have been improved with the use of more effective therapies, such as dosage intensification with methotrexate [64,82]. Future treatment improvements could be achieved based on the discovery of pathways for treatment resistance of *E2A-PBX1* positive cells. It has been shown that *MerTK* is activated by GAS6 (Growth arrest specific 6) produced in bone marrow by mesenchymal cells, which are part of the HSC supporting

is detected in B and T cell ALL and mantle cell lymphomas [93,94].

204 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

generally dissimilar suggesting different origins of the disease [3,98].

bryonic stem cells (hESC) [90].

Myeloid/lymphoid or Mixed lineage leukemia gene (*MLL, MLL1, ALL1, TRX*, and *HTRX*) is the human homologue of the *Drosophila melanogaster* trithorax gene; it is located at 11q23 and consists of 36 exons. It encodes a 430 kDa DNA binding protein that positively regulates *HOX* gene expression through methylation of lysine 4 of histone 3 (H3K4) [101]. MLL is a large multi-domain protein, the N-terminus contains three short AT-hook motifs (ATH 1–3), which are thought to mediate DNA binding. There are two speckled nuclear localization sites (SNL1 and SNL2) immediately C-terminal to the ATH motifs that are followed by a transcriptional repression domain consisting of two functional subunits, RD1 and RD2. RD1 contains a DNA methyltransferase (DMT) homology domain with a CxxC zinc-finger motif that might recruit transcriptional repressors. RD2 recruits histone deacetylases HDAC1 and HDAC2. There is also a plant homology domain (PHD) zinc-finger motif that might mediate protein-protein interactions and a C-terminal SET (Su(var)3-9, enchancer-of-zeste, trithorax) domain that possesses histone H3 lysine 4 (H3K4) methyltransferase activity [95]. Despite RD1 and RD2, MLL is thought to be primarily a transcriptional activator due to its methyl‐ transferase activity and to the transcriptional activation domain, which recruits the tran‐ scriptional co-activator CBP (CREB-binding protein). MLL is thought to be a master gene for epigenetic transcriptional memory regulation.

MLL in its mature form consists of two non-covalently associated subunits, an N-terminal 320 kDa fragment (MLLN) and a C-terminal 180 kDa moiety (MLLC), which are both core components of the MLL complex and result from the cleavage of nascent MLL by an aspart‐ ic protease named taspase 1. The MLLN fragment is thought to bind DNA regulatory regions of clustered *HOX* genes as part of a multi-subunit complex that includes components of the basal transcription machinery and mediate transcriptional repression of *HOX* genes. How‐ ever, in the presence of MLLC, the MLLN complex can lead to transcriptional activation. The MLLC subunit contains the SET motif and associates with at least four proteins that modify chromatin for efficient transcription through methylation, acetylation and nucleosome re‐ modeling processes [101,102]. *MLL* gene is ubiquitously expressed in haematopoietic cells including stem and progenitor populations, and *HOX* genes are direct targets of MLL dur‐ ing development [7,95,102]. Also, MLL is a key constituent of the mammalian DNA damage response pathway, and it is reported that deregulation of the S-phase checkpoint mediated by *MLL* aberrations contributes to the pathogenesis of human *MLL* positive leukemias [103].

as potential inductors of *MLL* aberrations [80,106–110]. Additionally, the best-known induc‐ tor of *MLL* aberrations is etoposide, which is a DNA topoisomerase-II inhibitor commonly used as a chemotherapeutic agent. Etoposide induced genetic aberrations might be due to increased concentrations of DNA topoisomerase-II DNA cleavage complex. 11q23 rear‐ rangements, particularly those that generate *MLL-AF9* fusions, are found in 5-15% of secon‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

207

As mentioned before, the frequency of *MLL* rearrangements in IAL, particularly the *MLL-AF4* fusion, is approximately 80%; however, this frequency diminishes in older children with ALL. *MLL* rearrangements incidences reported from American countries ranged from 2.2-3.3%, while for European countries (Germany, Italy, Austria, UK and Switzerland) was between 2.1-6%. The incidence of *MLL* rearrangements in Eastern countries (China, Taiwan, Malaysia and Singapore) also ranged from 2.1-4.9%. The estimated 5-year EFS for patients with *MLL* translocations ranged between 30-40% [4] and therefore it is considered of very

*RUNX1* (Runt-related transcription factor 1 and also known as *AML1* or *CBFα2*) is a gene that maps in 21q22.3. *RUNX1* encodes a transcription factor that contains a Runt domain es‐ sential for interaction with transcription factor CBFβ and for DNA binding [114]. The RUNX1-CBFβ heterodimer is a master regulator of early hematopoietic genes transcription. *ETV6* (E-Twenty-Six, also named *TEL*), is localized in 12p13.1, belongs to the *ets* transcrip‐ tion factor family, and contains two major domains: ETS and helix-loop-helix (HLH). ETV6 participates in fetal hematopoiesis of all lineages [115,116]. A substantial proportion (7-25% of children and 2% of adults, Table 1) of ALL patients present the *ETV6/RUNX1* fusion as a result of the translocation t(12;21)(p13;q21). The chimeric protein from this fusion contains the N-terminal region of ETV6 fused to almost all RUNX1, including the Runt domain. The ETV6 fragment losses the DNA binding domain but retains the protein binding domain that interacts with cellular proteins with transcriptional repression activity, N-CoR and mSin3a, producing stable repression complexes at the promoters of RUNX1 target genes. mSin3a transcriptional repressor function is due to a histone deacetylase activity(HDAC) [10] but the ETV6-RUNX1 fusion has additional repressor functions through sequestration of tran‐ scriptional complexes and competitive inhibition of the wild-type ETV6 activity [10,116].

Several abnormalities secondary to *ETV6-RUNX1* fusion have been detected, such as *ETV6* loss, *ETV6/RUNX1* duplication and extra copies of *RUNX1* originated by trisomy 21*.* Recent‐ ly, it has been described that *ETV6* loss occurs postnatally in more mature cells than the *ETV6-RUNX1* fusion. Analysis of this deletion revealed an unexpected similarity with SINE and LINE retrotransposons, suggesting their participation in this loss of heterozygosity-like mechanism of ETV6 loss. These findings are consistent with Greaves´ double hit model of

*ETV6/RUNX1* positive patients have been defined as a group with excellent outcome at 5 years follow-up, which cannot be identified by standard prognostic features [118,119]. In several studies based on different populations, this subgroup represented about 25% of cas‐

dary therapy-related leukemias [104,107,111–113].

leukemogenesis for this subtype of ALL [117].

bad prognosis.

**4.4.** *ETV6-RUNX1* **fusion**

Most *MLL* translocations initiate within a well-characterized 8.3 kb breakpoint cluster region that encompasses exons 5-11. This region is AT-rich, contains Alu, LINE, and MER repeti‐ tive sequences, putative DNA topoisomerase-II cleavage recognition sites, as well as a scaf‐ fold and matrix attachment region (SAR/MAR); these elements have been proposed to play a direct or indirect role in promoting 11q23 rearrangements [104]. The proposed mecha‐ nisms that yield *MLL* translocations include recombination of Alu elements, recombination mediated by topoisomerase-II poisons, and an error prone non-homologous end joining (NHEJ) of DSB [101,104]. *MLL* fusions are diverse, since it has been found in more than 70 different translocations with numerous partner genes. The most frequent are *AF4, AF9, ENL, AF10, ELL* and *AF6*. *MLL-AF4* results from the translocation t(4;11)(q21;q23) that is common‐ ly found in patients younger than one year of age (infant ALL), while *MLL-AF9* is generated by the translocation t(9;11)(p22;q23) that is more frequently seen in secondary, therapy-in‐ duced malignancies. Although infrequent, other type of rearrangement involving *MLL* is the partial tandem amplification [7].

All *MLL* fusions encode proteins that share a common transcriptional regulator function ca‐ pable of regulating HOX genes expression. Some of the *MLL* fusion partners are themselves chromatin modifiers that function in histone acetylation, whereas other fusion partners can recruit histone methyl-transferases, such as DOT1; methylation at lysine 79 of histone H3 catalyzed by DOT1 has been recognized as a hallmark of chromatin activated by MLL fusion proteins [7,102,104]. MLL fusion proteins efficiently transform hematopoietic cells into leu‐ kemic cells with stem cell-like self-renewal properties [7].

*MLL* translocations define subgroups of high risk ALL with specific clinical and biological characteristics associated to adverse prognosis. These subgroups include infant acute leuke‐ mia (IAL), therapy-related leukemia (a subtype of leukemia developed by patients previous‐ ly treated with etoposide after a cancer episode) and T cell ALL [102]. *MLL* translocations are found in approximately 10% of all human leukemias including ALL, AML and bipheno‐ typic (mixed lineage) leukaemia, this latter one is characterized by the expression of both myeloid and lymphoid antigens such as CD14 and CD19 in the leukemic blast [7,102]. *MLL* translocations are particularly frequent (70-80%) in high risk IAL.

*MLL-AF4* is one of the leukemia-inducing genetic rearrangements documented to emerge *in utero* during fetal hematopoiesis. Concordant *MLL-AF4* positive leukemia studies in identi‐ cal monozygotic twins demonstrated that both siblings share the same breakpoints, al‐ though the disease usually presents at different times in each twin [105]. Moreover, *MLL-AF4* can be detected in archived neonatal blood from Guthrie cards in IAL or in ALL patients. This evidence coupled with the short period of latency observed in patients that develop IAL, strongly suggests that some leukemia-driving gene fusions can be acquired prenatally [9,62,95]. These observations have raised the question if *in utero* exposition to spe‐ cific environmental mutagens can induce *MLL* breakage and anomalous recombination events. *In vitro* and *in vivo* assays have identified bioflavonoids, hormones and insecticides as potential inductors of *MLL* aberrations [80,106–110]. Additionally, the best-known induc‐ tor of *MLL* aberrations is etoposide, which is a DNA topoisomerase-II inhibitor commonly used as a chemotherapeutic agent. Etoposide induced genetic aberrations might be due to increased concentrations of DNA topoisomerase-II DNA cleavage complex. 11q23 rear‐ rangements, particularly those that generate *MLL-AF9* fusions, are found in 5-15% of secon‐ dary therapy-related leukemias [104,107,111–113].

As mentioned before, the frequency of *MLL* rearrangements in IAL, particularly the *MLL-AF4* fusion, is approximately 80%; however, this frequency diminishes in older children with ALL. *MLL* rearrangements incidences reported from American countries ranged from 2.2-3.3%, while for European countries (Germany, Italy, Austria, UK and Switzerland) was between 2.1-6%. The incidence of *MLL* rearrangements in Eastern countries (China, Taiwan, Malaysia and Singapore) also ranged from 2.1-4.9%. The estimated 5-year EFS for patients with *MLL* translocations ranged between 30-40% [4] and therefore it is considered of very bad prognosis.

#### **4.4.** *ETV6-RUNX1* **fusion**

ing development [7,95,102]. Also, MLL is a key constituent of the mammalian DNA damage response pathway, and it is reported that deregulation of the S-phase checkpoint mediated by *MLL* aberrations contributes to the pathogenesis of human *MLL* positive leukemias [103]. Most *MLL* translocations initiate within a well-characterized 8.3 kb breakpoint cluster region that encompasses exons 5-11. This region is AT-rich, contains Alu, LINE, and MER repeti‐ tive sequences, putative DNA topoisomerase-II cleavage recognition sites, as well as a scaf‐ fold and matrix attachment region (SAR/MAR); these elements have been proposed to play a direct or indirect role in promoting 11q23 rearrangements [104]. The proposed mecha‐ nisms that yield *MLL* translocations include recombination of Alu elements, recombination mediated by topoisomerase-II poisons, and an error prone non-homologous end joining (NHEJ) of DSB [101,104]. *MLL* fusions are diverse, since it has been found in more than 70 different translocations with numerous partner genes. The most frequent are *AF4, AF9, ENL, AF10, ELL* and *AF6*. *MLL-AF4* results from the translocation t(4;11)(q21;q23) that is common‐ ly found in patients younger than one year of age (infant ALL), while *MLL-AF9* is generated by the translocation t(9;11)(p22;q23) that is more frequently seen in secondary, therapy-in‐ duced malignancies. Although infrequent, other type of rearrangement involving *MLL* is the

206 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

All *MLL* fusions encode proteins that share a common transcriptional regulator function ca‐ pable of regulating HOX genes expression. Some of the *MLL* fusion partners are themselves chromatin modifiers that function in histone acetylation, whereas other fusion partners can recruit histone methyl-transferases, such as DOT1; methylation at lysine 79 of histone H3 catalyzed by DOT1 has been recognized as a hallmark of chromatin activated by MLL fusion proteins [7,102,104]. MLL fusion proteins efficiently transform hematopoietic cells into leu‐

*MLL* translocations define subgroups of high risk ALL with specific clinical and biological characteristics associated to adverse prognosis. These subgroups include infant acute leuke‐ mia (IAL), therapy-related leukemia (a subtype of leukemia developed by patients previous‐ ly treated with etoposide after a cancer episode) and T cell ALL [102]. *MLL* translocations are found in approximately 10% of all human leukemias including ALL, AML and bipheno‐ typic (mixed lineage) leukaemia, this latter one is characterized by the expression of both myeloid and lymphoid antigens such as CD14 and CD19 in the leukemic blast [7,102]. *MLL*

*MLL-AF4* is one of the leukemia-inducing genetic rearrangements documented to emerge *in utero* during fetal hematopoiesis. Concordant *MLL-AF4* positive leukemia studies in identi‐ cal monozygotic twins demonstrated that both siblings share the same breakpoints, al‐ though the disease usually presents at different times in each twin [105]. Moreover, *MLL-AF4* can be detected in archived neonatal blood from Guthrie cards in IAL or in ALL patients. This evidence coupled with the short period of latency observed in patients that develop IAL, strongly suggests that some leukemia-driving gene fusions can be acquired prenatally [9,62,95]. These observations have raised the question if *in utero* exposition to spe‐ cific environmental mutagens can induce *MLL* breakage and anomalous recombination events. *In vitro* and *in vivo* assays have identified bioflavonoids, hormones and insecticides

partial tandem amplification [7].

kemic cells with stem cell-like self-renewal properties [7].

translocations are particularly frequent (70-80%) in high risk IAL.

*RUNX1* (Runt-related transcription factor 1 and also known as *AML1* or *CBFα2*) is a gene that maps in 21q22.3. *RUNX1* encodes a transcription factor that contains a Runt domain es‐ sential for interaction with transcription factor CBFβ and for DNA binding [114]. The RUNX1-CBFβ heterodimer is a master regulator of early hematopoietic genes transcription. *ETV6* (E-Twenty-Six, also named *TEL*), is localized in 12p13.1, belongs to the *ets* transcrip‐ tion factor family, and contains two major domains: ETS and helix-loop-helix (HLH). ETV6 participates in fetal hematopoiesis of all lineages [115,116]. A substantial proportion (7-25% of children and 2% of adults, Table 1) of ALL patients present the *ETV6/RUNX1* fusion as a result of the translocation t(12;21)(p13;q21). The chimeric protein from this fusion contains the N-terminal region of ETV6 fused to almost all RUNX1, including the Runt domain. The ETV6 fragment losses the DNA binding domain but retains the protein binding domain that interacts with cellular proteins with transcriptional repression activity, N-CoR and mSin3a, producing stable repression complexes at the promoters of RUNX1 target genes. mSin3a transcriptional repressor function is due to a histone deacetylase activity(HDAC) [10] but the ETV6-RUNX1 fusion has additional repressor functions through sequestration of tran‐ scriptional complexes and competitive inhibition of the wild-type ETV6 activity [10,116].

Several abnormalities secondary to *ETV6-RUNX1* fusion have been detected, such as *ETV6* loss, *ETV6/RUNX1* duplication and extra copies of *RUNX1* originated by trisomy 21*.* Recent‐ ly, it has been described that *ETV6* loss occurs postnatally in more mature cells than the *ETV6-RUNX1* fusion. Analysis of this deletion revealed an unexpected similarity with SINE and LINE retrotransposons, suggesting their participation in this loss of heterozygosity-like mechanism of ETV6 loss. These findings are consistent with Greaves´ double hit model of leukemogenesis for this subtype of ALL [117].

*ETV6/RUNX1* positive patients have been defined as a group with excellent outcome at 5 years follow-up, which cannot be identified by standard prognostic features [118,119]. In several studies based on different populations, this subgroup represented about 25% of cas‐ es with B cell precursor immunophenotype [120]; and this genetic marker could also be found in T cell ALL [81]. Other studies support different incidence rates for *ETV6/RUNX1* fusions depending on ethnicity and geographic origin [83,85,121,122] (Table 1). In particular, the lowest frequencies have been described for Hispanic [83,121] and Oriental patients [85,123], compared to patients from West Europe and the United States. Given this differ‐ ence, further studies should be conducted looking for environmental and genetic etiologic factors, including exposure to leukemogenic agents, analysis of predisposition genes associ‐ ated to ALL and genetic ancestry in different populations.

changes between the leukemic blast at presentation and relapse most probably are due to

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

209

More recently, it has been shown that genes associated with glucocorticoid mediated apoptosis could be deleted in *ETV6/RUNX1* relapsed patients. One of the most altered genes is the Bcl2 modifying factor (BMF), whose deletion is often detected at diagnosis and relapse. The glucocorticoid receptor NR3C1, and genes of the mismatch repair path‐ ways are also deleted, but this was only observed at relapse. All these genes participate in apoptosis induced by gluococorticoids, supporting that a drug resistance mechanism could contribute to the episode of leukemia relapse, e.g. *BMF* deletions leading to surviv‐ al of a specific leukemic clone after gluococorticoid treatment [126]. This information is relevant for future evaluation of *ETV6/RUNX1* patients and perhaps this genetic lesion should be diagnosed in ALLs together with BMF, NR3C1 and other CNAs as a guide for

Hyperdiploidy with 51-65 chromosomes is also a frequent abnormality, 25-41% of ALL patients present this numerical aberration [10,83,85] and are generally associated with a favorable outcome (Table 1). This includes age 3-5 years and relative low WBC count at presentation, B cell precursor immunophenotype [127] and a 5-year EFS estimate of 85-95% when patients are treated with anti-metabolite based therapy [4,127]. Leukemic lymphoblasts in this subgroup have a high propensity to undergo apoptosis *in vitro* and *in vivo*, and accumulate greater quantities of methotrexate and its active polyglutamate metabolites than other ALL subgroups. These features are probably very important for

High hyperdiploidy can be detected by cytogenetic analysis or flow cytometry. This latter technique measures the DNA content of the leukemic blasts in comparison to the normal cell pool and DNA content of 1.16 is considered as a prognostic indicator of favorable outcome. However, it is recommended to perform additional cytogenetic studies to detect specific chromosome gains, and discard the presence of additional genetic rearrangements, which could also influence disease outcome. About 50% of hyperdiploid cases present additional abnormalities as duplications of 1q or isochromosome 17q, this last abnormality confers ad‐ verse prognosis [128]. High hyperdiploidy is often characterized cytogenetically by massive aneuploidy, originating a non-random gain of specific chromosomes, including some or all of +X, +4, +6, +10, +14, +17, +18, and +21; trisomies and tetrasomies of other chromosomes are

In spite of the excellent prognosis associated to this genetic subtype, about 25% of the patients develop adverse events, indicating outcome differences and genetic subgroups between high hyperdiploid patients. For this reason, diverse studies have been per‐ formed trying to identify prognostic characteristics in these ALL patients. Based on cyto‐ genetic studies and survival analyses, specific trisomies have been found associated to prognosis. Results from univariate analyses informed that gain of individual chromo‐ somes 6, 4, 10 and 18 improves prognosis, in contrast, trisomy 5 confers worse prognosis

the frequency and intrinsic genetic characteristics of the relapsed clone.

novel treatment approaches.

the associated good prognosis of this subtype of ALL.

also present in this group of patients [127].

**4.5. Hyperdiploidy**

Several studies have supported that *ETV6-RUNX1* positive patients have an excellent out‐ come in clinical trials after treatment with corticosteroids, vincristine, and asparaginase [82]. Nevertheless, *ETV6/RUNX1* has been considered as a non-significant prognostic factor in other studies, since this fusion has been found in relapsed patients [124,125]. In spite of their excellent initial treatment response, and favorable short-term outcome, up to 24% of patients relapse [124], and this usually occurs in patients out of treatment, often several years after cessation of treatment and occasionally as long as 10 to 20 years later [125]. Efforts have been made for obtaining a better understanding about the origin of relapses in this group of ALL patients. Analyses of copy number abnormalities (CNAs) have provided evidence that *ETV6-RUNX1* positive patients have an average of 6 CNAs at diagnosis, with increasing abundance of these CNAs at relapse, and the genes involved in CNAs usually include cell cycle regulator genes [125,126].

The clonal origin of relapse has been investigated comparing CNA profiles from matched *ETV6/RUNX1* positive patients at diagnosis and relapse. Genes associated with cell cycle control (cyclin-dependent kinase inhibitors *CDKN2A, CDKN2B, CCNC)* were found deleted in relapsed patients. As a novel finding, trisomy 16 was observed as a recurrent abnormali‐ ty, although its significance is presently unknown [125]. A model of abnormalities acquisi‐ tion from diagnosis to relapse has been proposed; mutations detected recurrently or known to be involved in a leukemogenic pathway were classified as driver mutations, while muta‐ tions defined as non-recurrent or without a known function in leukemogenesis were consid‐ ered passenger mutations. Four genetic profiles have been proposed with this analysis: 1) diagnosis and relapse clones with the same abnormalities; 2) relapse clones with acquired extra driver mutations; 3) relapse clones with losses and gains of driver mutations and 4) relapse clones without all original CNAs but with a novel profile of genetic alterations [125]. At least 3 of these groups support that clones present at diagnosis are responsible for relap‐ ses occurring months or years after treatment cessation. In one patient with a remission last‐ ing 119 months a backtracking FISH analysis was performed, and a low number of leukemic subclone was identified at presentation whose genotype matched that observed in the re‐ lapse clone. This patient showed clonal diversity at diagnosis and the relapse subclone prob‐ ably remained due to active mechanisms of chemotherapy resistance and quiescence. The authors suggested that this case of relapse represents an effect of a dormant clone with low proliferative capacity and associated drug insensitivity rather than a mutation-induced re‐ sistance effect [125]. This patient might exemplify the genetic variation sometimes observed between initiating and relapse clones. Thus, this study argues that evolutionary genetic changes between the leukemic blast at presentation and relapse most probably are due to the frequency and intrinsic genetic characteristics of the relapsed clone.

More recently, it has been shown that genes associated with glucocorticoid mediated apoptosis could be deleted in *ETV6/RUNX1* relapsed patients. One of the most altered genes is the Bcl2 modifying factor (BMF), whose deletion is often detected at diagnosis and relapse. The glucocorticoid receptor NR3C1, and genes of the mismatch repair path‐ ways are also deleted, but this was only observed at relapse. All these genes participate in apoptosis induced by gluococorticoids, supporting that a drug resistance mechanism could contribute to the episode of leukemia relapse, e.g. *BMF* deletions leading to surviv‐ al of a specific leukemic clone after gluococorticoid treatment [126]. This information is relevant for future evaluation of *ETV6/RUNX1* patients and perhaps this genetic lesion should be diagnosed in ALLs together with BMF, NR3C1 and other CNAs as a guide for novel treatment approaches.

#### **4.5. Hyperdiploidy**

es with B cell precursor immunophenotype [120]; and this genetic marker could also be found in T cell ALL [81]. Other studies support different incidence rates for *ETV6/RUNX1* fusions depending on ethnicity and geographic origin [83,85,121,122] (Table 1). In particular, the lowest frequencies have been described for Hispanic [83,121] and Oriental patients [85,123], compared to patients from West Europe and the United States. Given this differ‐ ence, further studies should be conducted looking for environmental and genetic etiologic factors, including exposure to leukemogenic agents, analysis of predisposition genes associ‐

Several studies have supported that *ETV6-RUNX1* positive patients have an excellent out‐ come in clinical trials after treatment with corticosteroids, vincristine, and asparaginase [82]. Nevertheless, *ETV6/RUNX1* has been considered as a non-significant prognostic factor in other studies, since this fusion has been found in relapsed patients [124,125]. In spite of their excellent initial treatment response, and favorable short-term outcome, up to 24% of patients relapse [124], and this usually occurs in patients out of treatment, often several years after cessation of treatment and occasionally as long as 10 to 20 years later [125]. Efforts have been made for obtaining a better understanding about the origin of relapses in this group of ALL patients. Analyses of copy number abnormalities (CNAs) have provided evidence that *ETV6-RUNX1* positive patients have an average of 6 CNAs at diagnosis, with increasing abundance of these CNAs at relapse, and the genes involved in CNAs usually include cell

The clonal origin of relapse has been investigated comparing CNA profiles from matched *ETV6/RUNX1* positive patients at diagnosis and relapse. Genes associated with cell cycle control (cyclin-dependent kinase inhibitors *CDKN2A, CDKN2B, CCNC)* were found deleted in relapsed patients. As a novel finding, trisomy 16 was observed as a recurrent abnormali‐ ty, although its significance is presently unknown [125]. A model of abnormalities acquisi‐ tion from diagnosis to relapse has been proposed; mutations detected recurrently or known to be involved in a leukemogenic pathway were classified as driver mutations, while muta‐ tions defined as non-recurrent or without a known function in leukemogenesis were consid‐ ered passenger mutations. Four genetic profiles have been proposed with this analysis: 1) diagnosis and relapse clones with the same abnormalities; 2) relapse clones with acquired extra driver mutations; 3) relapse clones with losses and gains of driver mutations and 4) relapse clones without all original CNAs but with a novel profile of genetic alterations [125]. At least 3 of these groups support that clones present at diagnosis are responsible for relap‐ ses occurring months or years after treatment cessation. In one patient with a remission last‐ ing 119 months a backtracking FISH analysis was performed, and a low number of leukemic subclone was identified at presentation whose genotype matched that observed in the re‐ lapse clone. This patient showed clonal diversity at diagnosis and the relapse subclone prob‐ ably remained due to active mechanisms of chemotherapy resistance and quiescence. The authors suggested that this case of relapse represents an effect of a dormant clone with low proliferative capacity and associated drug insensitivity rather than a mutation-induced re‐ sistance effect [125]. This patient might exemplify the genetic variation sometimes observed between initiating and relapse clones. Thus, this study argues that evolutionary genetic

ated to ALL and genetic ancestry in different populations.

208 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

cycle regulator genes [125,126].

Hyperdiploidy with 51-65 chromosomes is also a frequent abnormality, 25-41% of ALL patients present this numerical aberration [10,83,85] and are generally associated with a favorable outcome (Table 1). This includes age 3-5 years and relative low WBC count at presentation, B cell precursor immunophenotype [127] and a 5-year EFS estimate of 85-95% when patients are treated with anti-metabolite based therapy [4,127]. Leukemic lymphoblasts in this subgroup have a high propensity to undergo apoptosis *in vitro* and *in vivo*, and accumulate greater quantities of methotrexate and its active polyglutamate metabolites than other ALL subgroups. These features are probably very important for the associated good prognosis of this subtype of ALL.

High hyperdiploidy can be detected by cytogenetic analysis or flow cytometry. This latter technique measures the DNA content of the leukemic blasts in comparison to the normal cell pool and DNA content of 1.16 is considered as a prognostic indicator of favorable outcome. However, it is recommended to perform additional cytogenetic studies to detect specific chromosome gains, and discard the presence of additional genetic rearrangements, which could also influence disease outcome. About 50% of hyperdiploid cases present additional abnormalities as duplications of 1q or isochromosome 17q, this last abnormality confers ad‐ verse prognosis [128]. High hyperdiploidy is often characterized cytogenetically by massive aneuploidy, originating a non-random gain of specific chromosomes, including some or all of +X, +4, +6, +10, +14, +17, +18, and +21; trisomies and tetrasomies of other chromosomes are also present in this group of patients [127].

In spite of the excellent prognosis associated to this genetic subtype, about 25% of the patients develop adverse events, indicating outcome differences and genetic subgroups between high hyperdiploid patients. For this reason, diverse studies have been per‐ formed trying to identify prognostic characteristics in these ALL patients. Based on cyto‐ genetic studies and survival analyses, specific trisomies have been found associated to prognosis. Results from univariate analyses informed that gain of individual chromo‐ somes 6, 4, 10 and 18 improves prognosis, in contrast, trisomy 5 confers worse prognosis [129–131]. Currently, the Children's Cancer Group (CCG) and the Pediatric Oncology Group (POG) consider the presence of simultaneous trisomies of chromosomes 4, 10, and 17 as a favorable prognostic factor [132].

**5. Molecular and cytogenetic subgroups in pediatric T-cell ALL**

tion between *NUP214* and *ABL1* genes (Table 2) [35,141].

*NOTCH1 mutations* >50 Transmembrane receptor

**Genetic**

**t(10;14)(q24;q11) TLX1-TCR α/δ t(7;10)(q35;q24) TCR β-TLX1**

**t(1;14)(p32;q11) TAL1-TCR α/δ**

**t(7;9)(q34;q34.3) TCR β-NOTCH1**

**t(5;14)(q35;q32) TLX3-BCL11b**

**1p32 deletion SIL-TAL1**

HSC, Hematopoietic Stem Cell

**Table 2.** Translocations and mutations in T-ALL

T cell ALL is a neoplastic disorder characterized by malignant transformation of early thy‐ mocytes [37]. It accounts for approximately 10-15% of pediatric ALL cases [2,37,137–139] and tends to present clinically with high circulating blast cell counts, mediastinal masses, and often central nervous system involvement [37,140]. Therefore, it is a high risk ALL with a relapse rate of about 30% within the first 2 years following diagnosis [15,139]. T cell ALL is caused by genetic alterations leading to a variety of changes that can affect cell cycle control, unlimited self-renewal capacity, impaired differentiation and loss of sensitivity to death sig‐ nals [37]. As previously described, T cell ALL shares some chromosome rearrangements with B cell ALL; however, about 50% of T-ALL patients have recurrent chromosomal trans‐ locations specific of this subtype. The most common chromosome abnormalities include re‐ arrangements affecting the *TCR* regulatory elements: juxtaposing promoter and enhancer elements from the *TCRA/D* locus (T-cell receptor α/δ, 14q11) and *TCRB* (T-cell receptor β, 7q34) to developmentally important transcription factor genes such as homeobox genes (*TLX1, TLX3*); helix-loop-helix genes (*TAL1/SCL, TAL2, LYL1*) or LIM-domain genes (*LMO1, LMO2*) (Table 2) [15,37,139–142]. Other important genetic abnormalities frequently targeted during malignant transformation of T cells are interstitial deletion on *TAL1/SCL* and *NOTCH1* point mutations (Table 2). Translocations not involving *TCR* loci have also been described, relevant examples are the gene fusion *CALM-AF10* and the episomal recombina‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

211

**TCR-mediated translocations in T-ALL**

**abnormalities Frequency (%) Function Outcome References**

Spleen development

HSC survival

T-cell development

Neural development

T-cell development

17 bHLH transcription factor Undefined [15,37]

Good [37,38,143]

Undefined [15,37]

Poor [35–38]

Poor [37,38,137]

Poor [35–38]

4-10 Homeodomain transcription factor

<sup>3</sup> bHLH transcription factor

<1 Transmembrane receptor

**Non-TCR-mediated translocations and mutations in T-ALL**

<sup>20</sup> Homeodomain transcription factor

Analysis by SNP array of high hyperdiploid patients have been performed and revealed that 80% presented CNAs, which are not detected by traditional cytogenetic methods. An association between duplication of 1q and +5 has often been observed, and also uniparental isodisomies of chromosomes 9 and 11, gains of chromosomes 17q and 21q, deletions and mi‐ crodeletions of *ETV6*, cyclin-dependent kinase inhibitor 2A (*CKDN2A*), *PAX5* and PAN3 poly(A) specific ribonuclease subunit homolog (*PAN3*). Interestingly, partial deletions of AT rich interactive domain 5B (*ARID5B*) were also detected [127] and polymorphisms of this gene were recently associated to susceptibility for developing ALL, particularly associated with the high hyperdiploid subtype [133].

ALL cases with 47-50 chromosomes have an intermediate prognosis [71], near-triploidy (69 to 81 chromosomes) [134] have a response to therapy similar to that of non-hyperdiploid, and ALL cases with near tetraploidy (82 to 94 chromosomes) have a high frequency of T cell immunophenotype (see T cell ALL section) and frequently harbors a cryptic ETV6-RUNX1 fusion [135]. These tetraploid leukemias, although significantly less common, have a worse prognosis than the ones with 51-65 chromosomes. The genetic reason for this differential prognosis is presently unclear.

#### **4.6. Hypodiploidy**

The hypodiploid ALL is defined as leukemic blasts with less that 46 chromosomes and it is present in 6-7% of patients with childhood ALL. Three different subgroups have been defined according to the number of chromosomes, which are also important for disease outcome: near-haploid ALL (less than 30 chromosomes), low hypodiploid ALL (33-39 chromosomes) and high hypodiploid ALL (42-45 chromosomes). Near-hap‐ loidy is observed approximately in 0.5% of ALL cases and it is most frequently associ‐ ated with females, and together with low hypodiploidy is related with the worst prognosis. Also, children with near-haploidy tend to be younger than those with low hypodiploidy [134,136]. Most of the hypodiploid ALL patients belong to the high hy‐ podiploid group.

The pattern of chromosome loss in near-haploidy is not random as there is preferential re‐ tention of two copies of chromosomes 6, 8, 10, 14, 18, 21, and the sex chromosomes. In rare cases, an apparent hyperdiploid genome is observed but the number of chromosomes re‐ sults from doubling haploid or near-haploid chromosome content. In these cases, although there is an increased in the total number of chromosomes, this ALL is still characterized by losses of specific chromosomes. This ALL is frequently wrongly diagnosed without a careful cytogenetic and DNA content analysis [136], and an appropriate diagnosis is important as near-haploidy defines a rare type of ALL associated with short remission duration and poor prognosis. Therefore, a clear diagnosis of the total chromosome number is essential to strati‐ fy patients into the appropriate risk group.

## **5. Molecular and cytogenetic subgroups in pediatric T-cell ALL**

[129–131]. Currently, the Children's Cancer Group (CCG) and the Pediatric Oncology Group (POG) consider the presence of simultaneous trisomies of chromosomes 4, 10, and

Analysis by SNP array of high hyperdiploid patients have been performed and revealed that 80% presented CNAs, which are not detected by traditional cytogenetic methods. An association between duplication of 1q and +5 has often been observed, and also uniparental isodisomies of chromosomes 9 and 11, gains of chromosomes 17q and 21q, deletions and mi‐ crodeletions of *ETV6*, cyclin-dependent kinase inhibitor 2A (*CKDN2A*), *PAX5* and PAN3 poly(A) specific ribonuclease subunit homolog (*PAN3*). Interestingly, partial deletions of AT rich interactive domain 5B (*ARID5B*) were also detected [127] and polymorphisms of this gene were recently associated to susceptibility for developing ALL, particularly associated

ALL cases with 47-50 chromosomes have an intermediate prognosis [71], near-triploidy (69 to 81 chromosomes) [134] have a response to therapy similar to that of non-hyperdiploid, and ALL cases with near tetraploidy (82 to 94 chromosomes) have a high frequency of T cell immunophenotype (see T cell ALL section) and frequently harbors a cryptic ETV6-RUNX1 fusion [135]. These tetraploid leukemias, although significantly less common, have a worse prognosis than the ones with 51-65 chromosomes. The genetic reason for this differential

The hypodiploid ALL is defined as leukemic blasts with less that 46 chromosomes and it is present in 6-7% of patients with childhood ALL. Three different subgroups have been defined according to the number of chromosomes, which are also important for disease outcome: near-haploid ALL (less than 30 chromosomes), low hypodiploid ALL (33-39 chromosomes) and high hypodiploid ALL (42-45 chromosomes). Near-hap‐ loidy is observed approximately in 0.5% of ALL cases and it is most frequently associ‐ ated with females, and together with low hypodiploidy is related with the worst prognosis. Also, children with near-haploidy tend to be younger than those with low hypodiploidy [134,136]. Most of the hypodiploid ALL patients belong to the high hy‐

The pattern of chromosome loss in near-haploidy is not random as there is preferential re‐ tention of two copies of chromosomes 6, 8, 10, 14, 18, 21, and the sex chromosomes. In rare cases, an apparent hyperdiploid genome is observed but the number of chromosomes re‐ sults from doubling haploid or near-haploid chromosome content. In these cases, although there is an increased in the total number of chromosomes, this ALL is still characterized by losses of specific chromosomes. This ALL is frequently wrongly diagnosed without a careful cytogenetic and DNA content analysis [136], and an appropriate diagnosis is important as near-haploidy defines a rare type of ALL associated with short remission duration and poor prognosis. Therefore, a clear diagnosis of the total chromosome number is essential to strati‐

17 as a favorable prognostic factor [132].

210 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

with the high hyperdiploid subtype [133].

prognosis is presently unclear.

**4.6. Hypodiploidy**

podiploid group.

fy patients into the appropriate risk group.

T cell ALL is a neoplastic disorder characterized by malignant transformation of early thy‐ mocytes [37]. It accounts for approximately 10-15% of pediatric ALL cases [2,37,137–139] and tends to present clinically with high circulating blast cell counts, mediastinal masses, and often central nervous system involvement [37,140]. Therefore, it is a high risk ALL with a relapse rate of about 30% within the first 2 years following diagnosis [15,139]. T cell ALL is caused by genetic alterations leading to a variety of changes that can affect cell cycle control, unlimited self-renewal capacity, impaired differentiation and loss of sensitivity to death sig‐ nals [37]. As previously described, T cell ALL shares some chromosome rearrangements with B cell ALL; however, about 50% of T-ALL patients have recurrent chromosomal trans‐ locations specific of this subtype. The most common chromosome abnormalities include re‐ arrangements affecting the *TCR* regulatory elements: juxtaposing promoter and enhancer elements from the *TCRA/D* locus (T-cell receptor α/δ, 14q11) and *TCRB* (T-cell receptor β, 7q34) to developmentally important transcription factor genes such as homeobox genes (*TLX1, TLX3*); helix-loop-helix genes (*TAL1/SCL, TAL2, LYL1*) or LIM-domain genes (*LMO1, LMO2*) (Table 2) [15,37,139–142]. Other important genetic abnormalities frequently targeted during malignant transformation of T cells are interstitial deletion on *TAL1/SCL* and *NOTCH1* point mutations (Table 2). Translocations not involving *TCR* loci have also been described, relevant examples are the gene fusion *CALM-AF10* and the episomal recombina‐ tion between *NUP214* and *ABL1* genes (Table 2) [35,141].


**Table 2.** Translocations and mutations in T-ALL

#### **5.1. Impaired differentiation caused by defects in transcription factors expression/ function**

quence of a cryptic interstitial deletion that generates a *SIL-TAL1* fusion, and in 3% of pa‐ tients, t(1;14)(p32;q11) juxtaposes *TAL1* to TCR transcriptional regulatory elements causing its ectopic expression [37]. Ectopic *TAL1* expression is associated with a maturation arrest of thymocytes. TAL1 protein could also induce overexpression of BCL2A1, resulting in antiapoptotic activities in the stage of T cell development arrest and a poor response to therapy,

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

213

It is documented that *TLX3* expression confers a poor response to treatment, whereas *TLX1* activation is significantly associated with a better prognosis in T cell ALL. A high percentage of cryptic abnormalities of *TLX1*, *TLX3* and *TAL1* genes (both translocations and deletions), are mostly detected only using FISH with specific probes for each type of alteration [35]. Re‐ cently, quantitative RT-PCR and expression microarrays have permitted a better and techni‐ cally simpler T cell ALL classification based on the differential oncogene expression pattern [35]. Most probably, these new methodologies will positively impact the outcome of T cell ALL patients, allowing for a better disease sub-typing and assignment of treatments with

A novel subgroup of early T cell precursor leukemia has been reported, characterized by si‐ multaneous expression of T cell/ stem-cell/myeloid markers and very poor prognosis when treated with standard intensive chemotherapy. Interestingly, this subgroup includes a part

The first alteration described affecting *NOTCH1* in T cell ALL was t(7;9)(q34;q34.3), which couples the coding sequences of the *NOTCH1* ICN to the *TCR β* locus. This alteration is present in <1% of T cell ALL patients [36,38,138]. Currently, gain-of-function mutations in *NOTCH1* are reported in >50% of all T cell leukemia patients. *NOTCH1* mutations are main‐ ly observed in the HD and PEST domains. Mutations in HD result in NOTCH1 constitutive activation and cell transformation. These HD NOTCH1 mutants are observed in an average of 44% of T cell ALL patients. The deletion of the PEST domain enhances NOTCH1 intracel‐ lular signaling and is present in 30% of patients. Both, HD and PEST mutations together are found in 17% of cases, and have a synergistic effect on NOTCH1 activation [35,38,138]. *NOTCH1* mutations are found in all developmental subtypes of T cell ALL, supporting that these mutations might occur very early in T cell progenitors [35], and in general, they repre‐ sent a marker of poor prognosis in patients with T cell ALL (Table 2) [138]. Zhu and cols reported that the outcome of patients with *NOTCH1* mutations varies according to the con‐ comitant expression of *TLX1* and/or *TLX3*. Patients additionally positive for *TLX3* expres‐ sion, have worse prognosis than those with *TLX1* expression since the latter ones tent to

Glucocorticoids are normally used to treat T cell ALL patients and glucocorticoid resistance have been mapped to NOTCH1 aberrant expression. Recently, a combination therapy with glucocorticoids and GSIs in a mouse model of resistant to treatment T cell ALL show prom‐ ising results, arguing that NOTCH1 inhibitors in combination with traditional anti-leukemic

drugs might improve disease prognosis in patients with NOTCH1 mutations [149].

particularly in young children [35,37,147,148].

of those patients with *LYL1* and *LMO1* overexpression [2].

**5.2. Activation of the NOTCH1 signaling pathway**

better therapeutic responses.

show prolonged survival [138].

#### *5.1.1. Deregulation of TLX1 and TLX3 Homeobox genes*

Homeobox genes (*HOX*) are divided into two classes: class I *HOX* genes (*HOXA-D*) and class two *HOX* genes (*TLX1* and *TLX3*). Class II *HOX* genes have been extensively studied In T cell ALL and from them *TLX1* has been found activated in 4-10% of childhood T cell ALL, most frequently by t(10;14)(q24;q11) and t(7;10)(q35;q24) chromosomal translocations [36,37,40,137,143–145]. Both rearrangements lead to the transcriptional activation of *TLX1* gene by re-location of *TLX1* coding sequences under the transcriptional control of the TCR regulatory sequences (Table 2) [36,37,40,137]. *TLX1* is not normally expressed in healthy T cells. Interestingly, overexpression of TLX1 has also been observed in absence of known translocations, suggesting that other mechanisms of up-regulation are involved. Epigenetic changes mediated by promoter demethylation can also lead to *TLX1* aberrant expression [36,137,145]. *TLX1*+ T cells are virtually all arrested at a developmental stage phenotypically similar to the early cortical (CD1+) CD4+CD8+ "double-positive" stage of thymocyte devel‐ opment (early cortical thymocytes) [40]. However, these leukemic T cells lack preTCR ex‐ pression suggesting that the oncogenic event occurred very early in development (probably to ETP/DN1 cells) and *TLX1* aberrant expression helped the cell to bypass the first develop‐ mental checkpoints until the cells were finally arrested at the double positive stage [139]. The favorable clinical outcome of patients with this phenotype might support the arrest in the double positive stage, since it is characterized by lack of expression of anti-apoptotic genes because of the tolerance and negative selection mechanisms that are at work to elimi‐ nate self-reactive T cell clones [35–37,143–145].

The cryptic chromosomal translocation t(5;14)(q35;q32) juxtaposes *TLX3* to the distal region of *BCL11B* producing a strong expression of *TLX3*, a genetic lesion present in approximately 20% of childhood T cell ALL (Table 2) [15,35–37,137,141]. Like *TLX1*, *TLX3* is not expressed during normal T cell development [36]. Rare variants of t(5;14) have also been reported: t(5;14)(q32;q11) involving *TRA/TRD* and t(5;7)(q35;q21) involving *CDK6* [35–37]. Some stud‐ ies indicated that *TLX3* confers a bad response to treatment, but this is controversial since variation has been found between different populations [139]. It is possible that the prognos‐ tic meaning of *TLX3* overexpression might be influenced by the presence of additional al‐ tered oncogenes such *NUP214-ABL1* or *NOTCH1* [15,37].

#### *5.1.2. Deregulation of TAL1, a basic Helix-Loop-Helix (bHLH) gene*

Two different models have explained the oncogenic potential and transformation mecha‐ nism of *TAL1*: 1) inappropriate activation of *TAL1* target genes and 2) through a dominantnegative mechanism in which *TAL1* binds to and inhibits the normal activity of the E2A (E47)/HEB transcription factor complex*.* The second mechanism suggests that E2A proteins may directly regulate cell cycle in thymocyte precursors [35,37,146]*. TAL1* maps on chromo‐ some 1p32 and abnormal function of this gene is one of the most common transcriptional defects in childhood T cell ALL (Table 2); in 17% of patients *TAL1* activation is a conse‐ quence of a cryptic interstitial deletion that generates a *SIL-TAL1* fusion, and in 3% of pa‐ tients, t(1;14)(p32;q11) juxtaposes *TAL1* to TCR transcriptional regulatory elements causing its ectopic expression [37]. Ectopic *TAL1* expression is associated with a maturation arrest of thymocytes. TAL1 protein could also induce overexpression of BCL2A1, resulting in antiapoptotic activities in the stage of T cell development arrest and a poor response to therapy, particularly in young children [35,37,147,148].

It is documented that *TLX3* expression confers a poor response to treatment, whereas *TLX1* activation is significantly associated with a better prognosis in T cell ALL. A high percentage of cryptic abnormalities of *TLX1*, *TLX3* and *TAL1* genes (both translocations and deletions), are mostly detected only using FISH with specific probes for each type of alteration [35]. Re‐ cently, quantitative RT-PCR and expression microarrays have permitted a better and techni‐ cally simpler T cell ALL classification based on the differential oncogene expression pattern [35]. Most probably, these new methodologies will positively impact the outcome of T cell ALL patients, allowing for a better disease sub-typing and assignment of treatments with better therapeutic responses.

A novel subgroup of early T cell precursor leukemia has been reported, characterized by si‐ multaneous expression of T cell/ stem-cell/myeloid markers and very poor prognosis when treated with standard intensive chemotherapy. Interestingly, this subgroup includes a part of those patients with *LYL1* and *LMO1* overexpression [2].

#### **5.2. Activation of the NOTCH1 signaling pathway**

**5.1. Impaired differentiation caused by defects in transcription factors expression/**

Homeobox genes (*HOX*) are divided into two classes: class I *HOX* genes (*HOXA-D*) and class two *HOX* genes (*TLX1* and *TLX3*). Class II *HOX* genes have been extensively studied In T cell ALL and from them *TLX1* has been found activated in 4-10% of childhood T cell ALL, most frequently by t(10;14)(q24;q11) and t(7;10)(q35;q24) chromosomal translocations [36,37,40,137,143–145]. Both rearrangements lead to the transcriptional activation of *TLX1* gene by re-location of *TLX1* coding sequences under the transcriptional control of the TCR regulatory sequences (Table 2) [36,37,40,137]. *TLX1* is not normally expressed in healthy T cells. Interestingly, overexpression of TLX1 has also been observed in absence of known translocations, suggesting that other mechanisms of up-regulation are involved. Epigenetic changes mediated by promoter demethylation can also lead to *TLX1* aberrant expression [36,137,145]. *TLX1*+ T cells are virtually all arrested at a developmental stage phenotypically similar to the early cortical (CD1+) CD4+CD8+ "double-positive" stage of thymocyte devel‐ opment (early cortical thymocytes) [40]. However, these leukemic T cells lack preTCR ex‐ pression suggesting that the oncogenic event occurred very early in development (probably to ETP/DN1 cells) and *TLX1* aberrant expression helped the cell to bypass the first develop‐ mental checkpoints until the cells were finally arrested at the double positive stage [139]. The favorable clinical outcome of patients with this phenotype might support the arrest in the double positive stage, since it is characterized by lack of expression of anti-apoptotic genes because of the tolerance and negative selection mechanisms that are at work to elimi‐

The cryptic chromosomal translocation t(5;14)(q35;q32) juxtaposes *TLX3* to the distal region of *BCL11B* producing a strong expression of *TLX3*, a genetic lesion present in approximately 20% of childhood T cell ALL (Table 2) [15,35–37,137,141]. Like *TLX1*, *TLX3* is not expressed during normal T cell development [36]. Rare variants of t(5;14) have also been reported: t(5;14)(q32;q11) involving *TRA/TRD* and t(5;7)(q35;q21) involving *CDK6* [35–37]. Some stud‐ ies indicated that *TLX3* confers a bad response to treatment, but this is controversial since variation has been found between different populations [139]. It is possible that the prognos‐ tic meaning of *TLX3* overexpression might be influenced by the presence of additional al‐

Two different models have explained the oncogenic potential and transformation mecha‐ nism of *TAL1*: 1) inappropriate activation of *TAL1* target genes and 2) through a dominantnegative mechanism in which *TAL1* binds to and inhibits the normal activity of the E2A (E47)/HEB transcription factor complex*.* The second mechanism suggests that E2A proteins may directly regulate cell cycle in thymocyte precursors [35,37,146]*. TAL1* maps on chromo‐ some 1p32 and abnormal function of this gene is one of the most common transcriptional defects in childhood T cell ALL (Table 2); in 17% of patients *TAL1* activation is a conse‐

*5.1.1. Deregulation of TLX1 and TLX3 Homeobox genes*

212 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

nate self-reactive T cell clones [35–37,143–145].

tered oncogenes such *NUP214-ABL1* or *NOTCH1* [15,37].

*5.1.2. Deregulation of TAL1, a basic Helix-Loop-Helix (bHLH) gene*

**function**

The first alteration described affecting *NOTCH1* in T cell ALL was t(7;9)(q34;q34.3), which couples the coding sequences of the *NOTCH1* ICN to the *TCR β* locus. This alteration is present in <1% of T cell ALL patients [36,38,138]. Currently, gain-of-function mutations in *NOTCH1* are reported in >50% of all T cell leukemia patients. *NOTCH1* mutations are main‐ ly observed in the HD and PEST domains. Mutations in HD result in NOTCH1 constitutive activation and cell transformation. These HD NOTCH1 mutants are observed in an average of 44% of T cell ALL patients. The deletion of the PEST domain enhances NOTCH1 intracel‐ lular signaling and is present in 30% of patients. Both, HD and PEST mutations together are found in 17% of cases, and have a synergistic effect on NOTCH1 activation [35,38,138]. *NOTCH1* mutations are found in all developmental subtypes of T cell ALL, supporting that these mutations might occur very early in T cell progenitors [35], and in general, they repre‐ sent a marker of poor prognosis in patients with T cell ALL (Table 2) [138]. Zhu and cols reported that the outcome of patients with *NOTCH1* mutations varies according to the con‐ comitant expression of *TLX1* and/or *TLX3*. Patients additionally positive for *TLX3* expres‐ sion, have worse prognosis than those with *TLX1* expression since the latter ones tent to show prolonged survival [138].

Glucocorticoids are normally used to treat T cell ALL patients and glucocorticoid resistance have been mapped to NOTCH1 aberrant expression. Recently, a combination therapy with glucocorticoids and GSIs in a mouse model of resistant to treatment T cell ALL show prom‐ ising results, arguing that NOTCH1 inhibitors in combination with traditional anti-leukemic drugs might improve disease prognosis in patients with NOTCH1 mutations [149].

## **6. New prognostic markers detected by genomic variation assays and gene expression evaluation in childhood ALL**

ed higher relapse rates, lower relapse free survival and lower overall survival, in com‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

215

Biologic basis of the variation of *CASP8AP2* expression could be deletions at band 6q15-16.1, which are often detected in patients with T cell ALL. This abnormality results in down regulation of *CASP8AP2* expression and poor response to early treatment. In 73 T cell ALL samples obtained from patients enrolled in the multicenter ALL-BFM 1990, ALL-BFM 1995 and ALL-BFM 2000 protocols, deletion 6q15-16.1 was associated with un‐ favorable MRD levels. Although deletion 6q15-16.1 involves several genes, *CASP8AP2* was the single gene with a better association between the deletion and the less efficient

The usefulness of *CASP8AP2* expression as a potential marker of early response to treatment and relapse is still controversial. Yang et. al. [157] failed to show prognostic significance for this gene expression in a group of 78 B cell ALL and 12 T cell ALL newly diagnosed patients enrolled in the Taiwan Pediatric Oncology Group (TPOG). Further studies should be per‐ formed in ALL children from different populations and measuring different treatment pro‐

The *IKZF1* or *LyF1* gene encodes Ikaros, a transcription factor located on chromosome 7p12, whose largest transcript comprises 6 zinc finger domains in 7 exons; four of these fingers are required for DNA binding and the other 2 for homo and heterodimeric associations with

*IKZF1* encodes 11 isoforms through a mechanism of alternative splicing, each isoform con‐ taining a different set of zinc finger domains dictating differential DNA binding capabilities. Five of these isoforms (Ik-1, Ik-2, Ik-2A, Ik-3 and Ik-3A,) are considered as "long" and func‐ tional, because they conserve at least 3 N-terminal DNA binding domains, which permit them entering to the nucleus and presenting high transcriptional activity. The remaining iso‐ forms are referred as "short" (Ik-4, Ik-4A, Ik-5, Ik-6, Ik-7 and Ik-8) and have 2 or less N-ter‐ minal DNA binding domains. They are unable to bind DNA with high affinity, do not enter the nucleus, therefore neither activate transcription, but retain the protein binding domains and then the ability to form homo and heterodimers. This group might act as non-DNAbinding dominant-negative isoforms, reducing Ikaros activity. In particular, Ik-6 is not effi‐

ciently translocated to the nucleus, resulting in null transcriptional activity [162,163].

Ikaros plays an essential role in development and differentiation of lymphoid and myeloid lineages. It acts as a tumor suppressor and as a regulator of gene expression through a chro‐ matin remodeling function. In normal cells, long Ik-1 and Ik-2 isoforms are more expressed than the predominantly dominant-negative isoforms, Ik-3, Ik-4, Ik-5 and Ik-6 [162,163]. Dur‐ ing alternative splicing Ikaros is susceptible to loss the amino-terminal DNA-binding do‐ main, leading to increased expression of specific isoforms, in particular Ik-6, which is

parison to the high-expression group [160].

induction of apoptosis by chemotherapy [161].

**6.2.** *IKZF1*

tocols in order to clarify the prognostic significance of *CASP8AP2*.

other Ikaros family members, for example Helios and Aiolos [162].

strongly associated with B and T cell ALL [164–166].

The previously described genetic abnormalities in ALL influence the aggressive behavior of leukemic cells and the response to treatment in an important manner. Unfortunately, those abnormalities are not 100% predictive of disease outcome. More recently, genome wide analysis has identified genes associated with risk to relapse in patients with primary gene fusions and hyperdiploidy. These studies have also found novel gene abnormalities proba‐ bly leading to altered signaling pathways and gene expression patterns in the leukemic blast. Nowadays, many novel cryptic translocations, mutations, deletions, and abnormal ex‐ pression profiles are considered useful outcome markers in children with ALL and several of these more common markers will be further detailed in this section.

#### **6.1.** *CASP8AP2*

The Caspase-8-Associated Protein 2 gene, also known as FLICE associated Huge Protein (*CASP8AP2* or *FLASH*), is located at 6q15. *CASP8AP2* encodes a protein with multiple functions; although it has been traditionally recognized as a key mediator of apoptosis, several studies have demonstrated that also participates in cell division [150], NF-kappaB signaling [151,152], c-Myb activation [153,154], S phase progression [155], histone tran‐ scription and 3´-end maturation of histone mRNAs [155–157]. CASP8AP2 interacts with the death-effector domain (DED) of caspase 8 and hence it plays an important regulatory role in Fas-mediated apoptosis.

The clinical significance of *CASP8AP2* was first reported in Flotho and cols study [158], in which differences in expression levels were associated with *in vivo* responses to multiagent chemotherapy. *CASP8AP2* expression was analyzed in 99 patients enrolled in St Jude Total Therapy Study XIII and patients were divided into 3 groups according to expression. Pa‐ tients with high expression levels had significantly better EFS rates and lower cumulative incidences of relapse than those with intermediate or low *CASP8AP2* expression. The proapoptotic function of CASP8AP2 and its low expression in leukemic blasts from patients with persistent MRD, suggest that this gene could be a powerful predictor of treatment re‐ sponse in childhood ALL. Furthermore, Flotho and cols [159] identified a signature of 14 genes associated with MRD, and *CASP8AP2* was among the signature genes with a low lev‐ el expression. Other genes down regulated in these high risk patients were the H2A histone family member Z (*H2AFZ*), budding uninhibited by benzimidazoles 3 homolog (*BUB3*) and CDC28 protein kinase regulatory subunit 1B (*CKS1B*). All these patients showed suboptimal responses to remission induction therapy and they eventually relapsed [159].

Analyses of *CASP8AP2* as a prognostic marker used for risk stratification have been made in leukemic patients from different populations. In a cohort of 39 newly diagnosed ALL patients enrolled in Beijing Children`s Hospital (BCH)-ALL 2003 protocol, the bone marrow expression of *CASP8AP2* at diagnosis was an useful indicator for relapse. In the same study, 106 patients enrolled in Chinese Children´s Leukemia Group (CCLG)-ALL 2008 protocol were also analyzed, and patients with low *CASP8AP2* expression present‐ ed higher relapse rates, lower relapse free survival and lower overall survival, in com‐ parison to the high-expression group [160].

Biologic basis of the variation of *CASP8AP2* expression could be deletions at band 6q15-16.1, which are often detected in patients with T cell ALL. This abnormality results in down regulation of *CASP8AP2* expression and poor response to early treatment. In 73 T cell ALL samples obtained from patients enrolled in the multicenter ALL-BFM 1990, ALL-BFM 1995 and ALL-BFM 2000 protocols, deletion 6q15-16.1 was associated with un‐ favorable MRD levels. Although deletion 6q15-16.1 involves several genes, *CASP8AP2* was the single gene with a better association between the deletion and the less efficient induction of apoptosis by chemotherapy [161].

The usefulness of *CASP8AP2* expression as a potential marker of early response to treatment and relapse is still controversial. Yang et. al. [157] failed to show prognostic significance for this gene expression in a group of 78 B cell ALL and 12 T cell ALL newly diagnosed patients enrolled in the Taiwan Pediatric Oncology Group (TPOG). Further studies should be per‐ formed in ALL children from different populations and measuring different treatment pro‐ tocols in order to clarify the prognostic significance of *CASP8AP2*.

#### **6.2.** *IKZF1*

**6. New prognostic markers detected by genomic variation assays and**

The previously described genetic abnormalities in ALL influence the aggressive behavior of leukemic cells and the response to treatment in an important manner. Unfortunately, those abnormalities are not 100% predictive of disease outcome. More recently, genome wide analysis has identified genes associated with risk to relapse in patients with primary gene fusions and hyperdiploidy. These studies have also found novel gene abnormalities proba‐ bly leading to altered signaling pathways and gene expression patterns in the leukemic blast. Nowadays, many novel cryptic translocations, mutations, deletions, and abnormal ex‐ pression profiles are considered useful outcome markers in children with ALL and several

The Caspase-8-Associated Protein 2 gene, also known as FLICE associated Huge Protein (*CASP8AP2* or *FLASH*), is located at 6q15. *CASP8AP2* encodes a protein with multiple functions; although it has been traditionally recognized as a key mediator of apoptosis, several studies have demonstrated that also participates in cell division [150], NF-kappaB signaling [151,152], c-Myb activation [153,154], S phase progression [155], histone tran‐ scription and 3´-end maturation of histone mRNAs [155–157]. CASP8AP2 interacts with the death-effector domain (DED) of caspase 8 and hence it plays an important regulatory

The clinical significance of *CASP8AP2* was first reported in Flotho and cols study [158], in which differences in expression levels were associated with *in vivo* responses to multiagent chemotherapy. *CASP8AP2* expression was analyzed in 99 patients enrolled in St Jude Total Therapy Study XIII and patients were divided into 3 groups according to expression. Pa‐ tients with high expression levels had significantly better EFS rates and lower cumulative incidences of relapse than those with intermediate or low *CASP8AP2* expression. The proapoptotic function of CASP8AP2 and its low expression in leukemic blasts from patients with persistent MRD, suggest that this gene could be a powerful predictor of treatment re‐ sponse in childhood ALL. Furthermore, Flotho and cols [159] identified a signature of 14 genes associated with MRD, and *CASP8AP2* was among the signature genes with a low lev‐ el expression. Other genes down regulated in these high risk patients were the H2A histone family member Z (*H2AFZ*), budding uninhibited by benzimidazoles 3 homolog (*BUB3*) and CDC28 protein kinase regulatory subunit 1B (*CKS1B*). All these patients showed suboptimal

responses to remission induction therapy and they eventually relapsed [159].

Analyses of *CASP8AP2* as a prognostic marker used for risk stratification have been made in leukemic patients from different populations. In a cohort of 39 newly diagnosed ALL patients enrolled in Beijing Children`s Hospital (BCH)-ALL 2003 protocol, the bone marrow expression of *CASP8AP2* at diagnosis was an useful indicator for relapse. In the same study, 106 patients enrolled in Chinese Children´s Leukemia Group (CCLG)-ALL 2008 protocol were also analyzed, and patients with low *CASP8AP2* expression present‐

**gene expression evaluation in childhood ALL**

214 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

**6.1.** *CASP8AP2*

role in Fas-mediated apoptosis.

of these more common markers will be further detailed in this section.

The *IKZF1* or *LyF1* gene encodes Ikaros, a transcription factor located on chromosome 7p12, whose largest transcript comprises 6 zinc finger domains in 7 exons; four of these fingers are required for DNA binding and the other 2 for homo and heterodimeric associations with other Ikaros family members, for example Helios and Aiolos [162].

*IKZF1* encodes 11 isoforms through a mechanism of alternative splicing, each isoform con‐ taining a different set of zinc finger domains dictating differential DNA binding capabilities. Five of these isoforms (Ik-1, Ik-2, Ik-2A, Ik-3 and Ik-3A,) are considered as "long" and func‐ tional, because they conserve at least 3 N-terminal DNA binding domains, which permit them entering to the nucleus and presenting high transcriptional activity. The remaining iso‐ forms are referred as "short" (Ik-4, Ik-4A, Ik-5, Ik-6, Ik-7 and Ik-8) and have 2 or less N-ter‐ minal DNA binding domains. They are unable to bind DNA with high affinity, do not enter the nucleus, therefore neither activate transcription, but retain the protein binding domains and then the ability to form homo and heterodimers. This group might act as non-DNAbinding dominant-negative isoforms, reducing Ikaros activity. In particular, Ik-6 is not effi‐ ciently translocated to the nucleus, resulting in null transcriptional activity [162,163].

Ikaros plays an essential role in development and differentiation of lymphoid and myeloid lineages. It acts as a tumor suppressor and as a regulator of gene expression through a chro‐ matin remodeling function. In normal cells, long Ik-1 and Ik-2 isoforms are more expressed than the predominantly dominant-negative isoforms, Ik-3, Ik-4, Ik-5 and Ik-6 [162,163]. Dur‐ ing alternative splicing Ikaros is susceptible to loss the amino-terminal DNA-binding do‐ main, leading to increased expression of specific isoforms, in particular Ik-6, which is strongly associated with B and T cell ALL [164–166].

On the other hand, SNP array analysis of B cell ALL children has revealed deletions of com‐ plete *IKZF1* locus; there were also deletions of coding exons 3 through 6, resulting in Ik-6 expression in B-ALL patients. It has also detected point mutations (R111, L117fs, G158S, H224fs, S402fs and E504fs); in particular G158 attenuates the DNA-binding activity and might act as a dominant-negative Ikaros allele. [167]. Approximately 28% of high risk B cell ALL patients, and 9% of unselected risk patients show *IKZF1* deletions [167,168]. Deletions in *IKZF1* in unselected B cell ALL Asian patients are present in 10-15%; this incidence is sim‐ ilar to the one previously seen in Caucasian countries [85,157].

CALL4 and MUTZ5, derived from B cell ALL patients without Down syndrome [183]. *JAK2* mutations in ALL are significantly associated with poor outcome and the prognosis is worse when are associated with *IKZF1* deletions; this is an important observation since it has been estimated that 87% of high risk ALL cases harbor *JAK2* mutations together with *IKZF1* dele‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

217

The *Cytokine receptor-like factor 2* or *CRLF2* gene also termed thymic stromal lymphopoietin receptor *(TSLPR*), encodes a type I cytokine receptor. This gene is located in the pseudoauto‐ somal region 1 (PAR1) at both sex chromosomes, X (Xp22.3) and Y (Yp11.3). CRLF2 forms a heterodimeric receptor with IL7Rα which binds the thymic stromal lymphopoietin (TSLP) ligand. CRLF2 plays an important role during T cell and dendritic cell development, pro‐ motes B cell survival and proliferation, and is involved in inflammation, allergic responses

Approximately 40% of children with B cell ALL have *CRLF2* cryptic genetic alterations, which induce abnormal signaling during B cell development [178]. *CRLF2* is involved in 2 types of genomic rearrangements: 1) an interstitial deletion within the PAR1 region of chro‐ mosome X or Y that places the *CRLF2* gene under the transcriptional control of the *P2RY8* promoter (*P2RY8-CRLF2*), and 2) two cryptic chromosomal translocations t(X;14)(p22; q32) and t(Y;14)(p11;q32), both involving the locus of the B cell antigen receptor heavy chain (fu‐ sion *IGH-CRLF2*) [183,185,186]. PAR1 deletions seem to be more frequent than *IGH-CRLF2* translocation, however some groups report that translocation is the most frequent; these ob‐ servations are still controversial. *CRLF2* rearrangements are associated with aberrant over‐ expression of *CRLF2* in B cell ALL patients and might contribute to the pathogenesis of the disease [187–190]. Approximately 50% of patients with high *CRLF2* expression present a *CRLF2* rearrangement. However, in a few studies, low *CRLF2* expression has been detected in ALL with the *P2RY8*-*CRLF2* rearrangement. This low expression could result from a low frequency of the leukemic clone with the *P2RY8*-*CRLF2* lesion within the heterogeneous

pool of leukemic blasts, further studies will be necessary to clarify it [85,187,190].

showed a high *CRLF2* expression, but not genomic alterations of the gene [187].

About 5-7% of Caucasian non-selected B cell ALL patients present *CRLF2* rearrangements and overexpression. This frequency increased to 16-19% in high risk B cell ALL patients; for this reason *CRLF2* abnormalities have been associated with adverse prognosis [85,178,183,186,189–191]. Occurrence of *CRLF2* abnormalities differs among ALL popula‐ tions, this is probably influenced by the ethnic origin. Harvey and colleagues found that 35.3% of Hispanic/Latin high risk B cell ALL patients have *CRLF2* rearrangements and high expression of its protein [188], this fact could explain in part the poor response to treatment observed in this group [178,187–190]. *CRLF2* analysis by different groups have demonstrat‐ ed that rearrangements in this gene do not coexist with other non-random ALL chromoso‐ mal abnormalities [186,189,190]; except for a couple of *BCR-ABL1* positive patients that

Rearrangements and overexpression of *CRLF2* and *JAK2* mutations are particularly abun‐ dant in B cell ALL children with Down syndrome, coexistence of both lesions have been

tions [182].

**6.4.** *CRLF2*

and malignant transformation [183,184].

"Short" and "long" isoforms can be expressed in leukemic cells from both B and T cell ALL patients, however, the frequency and expression levels seem to vary between specific immu‐ nophenotype and genetic subgroups [169,170]. For instance, Ph positive B cell ALL patients tend to have higher levels of Ik-6 in contrast to Ik-1 and Ik-2 [170]. Interestingly, one study found that *IKZF1* is deleted in 84% of Ph positive B cell ALL patients, supporting its impor‐ tant role in the pathogenesis of this genetic subtype [168]. Ik-6 has also been found overex‐ pressed in patients with the *MLL-AF4* fusion [171].

Regarding prognosis, there is a strong correlation between mutations, deletions in *IKZF1* or presence of non-functional Ikaros isoforms, and poor outcome in both B and T cell ALL pa‐ tients. Nevertheless, this association is independent of the presence of the *BCR-ABL1* fusion, since both Ph positive and negative patients have poor outcome when *IKZF1* is altered [167,168]. Furthermore, approximately 35% of ALL relapsed cases, this condition also con‐ tributes to chemotherapy resistance [172,173]. Events of relapse have been predicted in 79% of non-high risk ALL patients based in both MRD and *IKZF1* deletions [174]. Recently, a novel high risk ALL subgroup called "*BCR-ABL1* like" has been identified, 39% of them pre‐ sented *IKZF1* deletions or mutations and they had a highly unfavorable prognosis as that found in the Ph positive B cell ALL group. About 20% of the total of B cell ALL patients be‐ long to this "*BCR-ABL1* like" subgroup [175].

#### **6.3.** *JAK2*

The *JAK2* gene is located on 9p24 and encodes a kinase that belongs to the JAK family of protein tyrosine kinases (JAK1, JAK2, JAK3 and TYK2). All members of the JAK family are activated by tyrosine phosphorylation and participate in proliferation, differentiation, and cellular migration processes after activation. Additionally, JAK2 regulates apoptosis during hematopoiesis. After JAK2 is activated, this tyrosine phosphorylates STAT5 leading to its di‐ merization, nuclear translocation and regulation of its target genes. The JAK/STAT pathway is the main signaling mechanism for numerous cytokines and growth factors. Mutations in different members of the JAK family are associated with inflammatory disease, erythrocyto‐ sis and childhood ALL [176,177].

Recently, it has been shown that the mutation R683, within the JAK2 pseudokinase domain, is present in approximately 3-4% of childhood ALL patients [178]. About 10% of high risk B cell ALL patients are R683+, however, the incidence is increased in patients with Down syn‐ drome (18-28%) [179–181]. The incidence of *JAK2* mutations is about 10% in the high-risk "*BCR*-*ABL1* like" group [182]. *JAK2* mutations have also been observed in cell lines MHH- CALL4 and MUTZ5, derived from B cell ALL patients without Down syndrome [183]. *JAK2* mutations in ALL are significantly associated with poor outcome and the prognosis is worse when are associated with *IKZF1* deletions; this is an important observation since it has been estimated that 87% of high risk ALL cases harbor *JAK2* mutations together with *IKZF1* dele‐ tions [182].

#### **6.4.** *CRLF2*

On the other hand, SNP array analysis of B cell ALL children has revealed deletions of com‐ plete *IKZF1* locus; there were also deletions of coding exons 3 through 6, resulting in Ik-6 expression in B-ALL patients. It has also detected point mutations (R111, L117fs, G158S, H224fs, S402fs and E504fs); in particular G158 attenuates the DNA-binding activity and might act as a dominant-negative Ikaros allele. [167]. Approximately 28% of high risk B cell ALL patients, and 9% of unselected risk patients show *IKZF1* deletions [167,168]. Deletions in *IKZF1* in unselected B cell ALL Asian patients are present in 10-15%; this incidence is sim‐

"Short" and "long" isoforms can be expressed in leukemic cells from both B and T cell ALL patients, however, the frequency and expression levels seem to vary between specific immu‐ nophenotype and genetic subgroups [169,170]. For instance, Ph positive B cell ALL patients tend to have higher levels of Ik-6 in contrast to Ik-1 and Ik-2 [170]. Interestingly, one study found that *IKZF1* is deleted in 84% of Ph positive B cell ALL patients, supporting its impor‐ tant role in the pathogenesis of this genetic subtype [168]. Ik-6 has also been found overex‐

Regarding prognosis, there is a strong correlation between mutations, deletions in *IKZF1* or presence of non-functional Ikaros isoforms, and poor outcome in both B and T cell ALL pa‐ tients. Nevertheless, this association is independent of the presence of the *BCR-ABL1* fusion, since both Ph positive and negative patients have poor outcome when *IKZF1* is altered [167,168]. Furthermore, approximately 35% of ALL relapsed cases, this condition also con‐ tributes to chemotherapy resistance [172,173]. Events of relapse have been predicted in 79% of non-high risk ALL patients based in both MRD and *IKZF1* deletions [174]. Recently, a novel high risk ALL subgroup called "*BCR-ABL1* like" has been identified, 39% of them pre‐ sented *IKZF1* deletions or mutations and they had a highly unfavorable prognosis as that found in the Ph positive B cell ALL group. About 20% of the total of B cell ALL patients be‐

The *JAK2* gene is located on 9p24 and encodes a kinase that belongs to the JAK family of protein tyrosine kinases (JAK1, JAK2, JAK3 and TYK2). All members of the JAK family are activated by tyrosine phosphorylation and participate in proliferation, differentiation, and cellular migration processes after activation. Additionally, JAK2 regulates apoptosis during hematopoiesis. After JAK2 is activated, this tyrosine phosphorylates STAT5 leading to its di‐ merization, nuclear translocation and regulation of its target genes. The JAK/STAT pathway is the main signaling mechanism for numerous cytokines and growth factors. Mutations in different members of the JAK family are associated with inflammatory disease, erythrocyto‐

Recently, it has been shown that the mutation R683, within the JAK2 pseudokinase domain, is present in approximately 3-4% of childhood ALL patients [178]. About 10% of high risk B cell ALL patients are R683+, however, the incidence is increased in patients with Down syn‐ drome (18-28%) [179–181]. The incidence of *JAK2* mutations is about 10% in the high-risk "*BCR*-*ABL1* like" group [182]. *JAK2* mutations have also been observed in cell lines MHH-

ilar to the one previously seen in Caucasian countries [85,157].

216 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

pressed in patients with the *MLL-AF4* fusion [171].

long to this "*BCR-ABL1* like" subgroup [175].

sis and childhood ALL [176,177].

**6.3.** *JAK2*

The *Cytokine receptor-like factor 2* or *CRLF2* gene also termed thymic stromal lymphopoietin receptor *(TSLPR*), encodes a type I cytokine receptor. This gene is located in the pseudoauto‐ somal region 1 (PAR1) at both sex chromosomes, X (Xp22.3) and Y (Yp11.3). CRLF2 forms a heterodimeric receptor with IL7Rα which binds the thymic stromal lymphopoietin (TSLP) ligand. CRLF2 plays an important role during T cell and dendritic cell development, pro‐ motes B cell survival and proliferation, and is involved in inflammation, allergic responses and malignant transformation [183,184].

Approximately 40% of children with B cell ALL have *CRLF2* cryptic genetic alterations, which induce abnormal signaling during B cell development [178]. *CRLF2* is involved in 2 types of genomic rearrangements: 1) an interstitial deletion within the PAR1 region of chro‐ mosome X or Y that places the *CRLF2* gene under the transcriptional control of the *P2RY8* promoter (*P2RY8-CRLF2*), and 2) two cryptic chromosomal translocations t(X;14)(p22; q32) and t(Y;14)(p11;q32), both involving the locus of the B cell antigen receptor heavy chain (fu‐ sion *IGH-CRLF2*) [183,185,186]. PAR1 deletions seem to be more frequent than *IGH-CRLF2* translocation, however some groups report that translocation is the most frequent; these ob‐ servations are still controversial. *CRLF2* rearrangements are associated with aberrant over‐ expression of *CRLF2* in B cell ALL patients and might contribute to the pathogenesis of the disease [187–190]. Approximately 50% of patients with high *CRLF2* expression present a *CRLF2* rearrangement. However, in a few studies, low *CRLF2* expression has been detected in ALL with the *P2RY8*-*CRLF2* rearrangement. This low expression could result from a low frequency of the leukemic clone with the *P2RY8*-*CRLF2* lesion within the heterogeneous pool of leukemic blasts, further studies will be necessary to clarify it [85,187,190].

About 5-7% of Caucasian non-selected B cell ALL patients present *CRLF2* rearrangements and overexpression. This frequency increased to 16-19% in high risk B cell ALL patients; for this reason *CRLF2* abnormalities have been associated with adverse prognosis [85,178,183,186,189–191]. Occurrence of *CRLF2* abnormalities differs among ALL popula‐ tions, this is probably influenced by the ethnic origin. Harvey and colleagues found that 35.3% of Hispanic/Latin high risk B cell ALL patients have *CRLF2* rearrangements and high expression of its protein [188], this fact could explain in part the poor response to treatment observed in this group [178,187–190]. *CRLF2* analysis by different groups have demonstrat‐ ed that rearrangements in this gene do not coexist with other non-random ALL chromoso‐ mal abnormalities [186,189,190]; except for a couple of *BCR-ABL1* positive patients that showed a high *CRLF2* expression, but not genomic alterations of the gene [187].

Rearrangements and overexpression of *CRLF2* and *JAK2* mutations are particularly abun‐ dant in B cell ALL children with Down syndrome, coexistence of both lesions have been found in up to 45-60% [178,186]. For this group of patients, *CRLF2* rearrangements are more frequent than other ALL aberrations as high hyperdiploid, *ETV6-RUNX1, E2A-PBX1* and *MLL-AF4*. A point mutation in *CRLF2* (F232C) has been identified in 9% of Down syndrome cases leading to *CRLF2* overexpression [191]; it has been proposed that this alteration could be the first leukemogenic event in these children [178,183].

ing novel genetic abnormalities that influence the aggressive behavior of leukemic cells and in consequence the response to treatment. Recently, new mutations have been found in pa‐ tients with high hyperdiploidy or with *ETV6-RUNX1* fusion. These recent findings are im‐ portant in the stratification of these subgroups of patients. ALL is one of the best characterized malignancies at the genetic level, and the increased survival of ALL patients in recent years is without a doubt due to the knowledge of the genes involved in ALL etiology. Next generation technologies and discovery of new genetic markers will keep providing a better understanding of the disease and a more comprehensive biological frame to stratify patients into more reliable risk groups. This knowledge will also reveal potential therapeutic targets that could yield personalized treatments, increasing the number of cured ALL chil‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

219

To CONACyT FONSEC SSA/IMSS/ISSSTE//44402. (PPV) and CONACyT PhD grant 165427

1 Tissue Culture Laboratory, Department of Research in Human Genetics, National Pedia‐

2 Unit of Medical Research in Infectious and Parasitic Diseases, High Specialty Medical Care Unit of the Pediatric Hospital, National Medical Center XXI Century, Mexican Institute of

[1] Pérez-Saldivar ML, Fajardo-Gutiérrez A, Bernáldez-Ríos R, Martínez-Avalos A, Med‐ ina-Sanson A, Espinosa-Hernández L, et al. Childhood acute leukemias are frequent

[2] Coustan-Smith E, Mullighan CG, Onciu M, Behm FG, Raimondi SC, Pei D, et al. Ear‐ ly T-cell precursor leukaemia: a subtype of very high-risk acute lymphoblastic leu‐

[3] Pui C-H, Campana D. Childhood Leukemia. In Abeloff's Clinical Oncology. (ed.)

in Mexico City: descriptive epidemiology. BMC Cancer. 2011;11:355.

, A. Reyes-León1

, M.P. Navarrete-Meneses1

,

, C. Salas-Labadía1

and P. Pérez-Vera1

trics Institute, Secretariat of Health, Mexico City, Mexico

kaemia. Lancet Oncol. 2009 Feb;10(2):147–56.

Elsevier Inc: Churchill Livingstone; 2008. p. 2139–69.

dren with less adverse sequelae.

**Acknowledgements**

**Author details**

M.R. Juárez-Velázquez1

Social Security, Mexico City, Mexico

E.M. Fuentes-Pananá2

**References**

(RJV).

A strong interaction among *IKZF1* deletion, *CRLF2* overexpression and *JAK2* mutations has been described in B cell ALL. Recent studies support that 100% of B cell ALL pa‐ tients with *JAK2* mutations have *CRLF2* overexpression, however, the opposite is not true. Analyses of different children ALL populations have identified coexistence of these abnormalities: 81% of Hispanic/Latin patients present *CRLF2* overexpression and *IKZF1* deletions, and 69% of them have *JAK2* mutations [188]; in 40% of Caucasian patients with *CRLF2* overexpression *IKZF1* deletions have been found [189]; 95% of Chinese pa‐ tients with *JAK2* mutations also present high *CRLF2* expression [85]. In Dutch children with Down syndrome, deletions of *IKZF1* were found in 35%, *JAK2* mutations in 15% and *CRLF2* overexpression in 62% of cases [192].

According to these observations, it has been speculated that *IKZF1* deletion, *CRLF2* overex‐ pression and *JAK2* mutations collaborate during B lymphoid transformation perturbing the normal lymphoid development. Furthermore, cooperative mutations could contribute to in‐ crease the risk of relapse and promoting therapy resistance and treatment failure. Particular‐ ly, *CRLF2* alterations might be the first step in carcinogenic signaling, given that its overexpression is associated with activation of the STAT5 pathway through tyrosine phos‐ phorylation in primary B-cell progenitors [183,189,193].

## **7. Conclusions**

Progress in risk adapted treatment of childhood ALL can currently cure up to 80% of pa‐ tients. Prognostic factors including patient and disease characteristics as well as response to treatment, play a key role in stratification. Through exhaustive genetic characterization of ALL, gene fusions, point mutations, deletions and gross losses or gains of genetic material have been associated to prognosis. Recently, gene expression and comparative genomic hy‐ bridization microarrays have identified new potential genetic markers for predicting out‐ come. These markers have been evaluated in order to recognize patients prone to relapse, even when they present low risk characteristics by conventional parameters of risk stratifica‐ tion. Based on those studies, gene signatures, mutations and signaling pathways no previ‐ ously associated to ALL have been identified. Detected abnormalities are involved in diverse cellular processes, as cell cycle progression, cell death, and regulation of gene ex‐ pression. These activities directly influence how the leukemic blast responds to treatment, and have an important role in the relapse process. Novel genetic alterations that have been associated with poor outcome in ALL patients are rearrangements/mutations that trigger *CRLF2* overexpression; *JAK2* mutations; *IKZF1* deletions and mutations, and down expres‐ sion of *CASP8AP2*. Genomic analysis of relapse leukemic clones has also been useful detect‐ ing novel genetic abnormalities that influence the aggressive behavior of leukemic cells and in consequence the response to treatment. Recently, new mutations have been found in pa‐ tients with high hyperdiploidy or with *ETV6-RUNX1* fusion. These recent findings are im‐ portant in the stratification of these subgroups of patients. ALL is one of the best characterized malignancies at the genetic level, and the increased survival of ALL patients in recent years is without a doubt due to the knowledge of the genes involved in ALL etiology. Next generation technologies and discovery of new genetic markers will keep providing a better understanding of the disease and a more comprehensive biological frame to stratify patients into more reliable risk groups. This knowledge will also reveal potential therapeutic targets that could yield personalized treatments, increasing the number of cured ALL chil‐ dren with less adverse sequelae.

## **Acknowledgements**

found in up to 45-60% [178,186]. For this group of patients, *CRLF2* rearrangements are more frequent than other ALL aberrations as high hyperdiploid, *ETV6-RUNX1, E2A-PBX1* and *MLL-AF4*. A point mutation in *CRLF2* (F232C) has been identified in 9% of Down syndrome cases leading to *CRLF2* overexpression [191]; it has been proposed that this alteration could

A strong interaction among *IKZF1* deletion, *CRLF2* overexpression and *JAK2* mutations has been described in B cell ALL. Recent studies support that 100% of B cell ALL pa‐ tients with *JAK2* mutations have *CRLF2* overexpression, however, the opposite is not true. Analyses of different children ALL populations have identified coexistence of these abnormalities: 81% of Hispanic/Latin patients present *CRLF2* overexpression and *IKZF1* deletions, and 69% of them have *JAK2* mutations [188]; in 40% of Caucasian patients with *CRLF2* overexpression *IKZF1* deletions have been found [189]; 95% of Chinese pa‐ tients with *JAK2* mutations also present high *CRLF2* expression [85]. In Dutch children with Down syndrome, deletions of *IKZF1* were found in 35%, *JAK2* mutations in 15%

According to these observations, it has been speculated that *IKZF1* deletion, *CRLF2* overex‐ pression and *JAK2* mutations collaborate during B lymphoid transformation perturbing the normal lymphoid development. Furthermore, cooperative mutations could contribute to in‐ crease the risk of relapse and promoting therapy resistance and treatment failure. Particular‐ ly, *CRLF2* alterations might be the first step in carcinogenic signaling, given that its overexpression is associated with activation of the STAT5 pathway through tyrosine phos‐

Progress in risk adapted treatment of childhood ALL can currently cure up to 80% of pa‐ tients. Prognostic factors including patient and disease characteristics as well as response to treatment, play a key role in stratification. Through exhaustive genetic characterization of ALL, gene fusions, point mutations, deletions and gross losses or gains of genetic material have been associated to prognosis. Recently, gene expression and comparative genomic hy‐ bridization microarrays have identified new potential genetic markers for predicting out‐ come. These markers have been evaluated in order to recognize patients prone to relapse, even when they present low risk characteristics by conventional parameters of risk stratifica‐ tion. Based on those studies, gene signatures, mutations and signaling pathways no previ‐ ously associated to ALL have been identified. Detected abnormalities are involved in diverse cellular processes, as cell cycle progression, cell death, and regulation of gene ex‐ pression. These activities directly influence how the leukemic blast responds to treatment, and have an important role in the relapse process. Novel genetic alterations that have been associated with poor outcome in ALL patients are rearrangements/mutations that trigger *CRLF2* overexpression; *JAK2* mutations; *IKZF1* deletions and mutations, and down expres‐ sion of *CASP8AP2*. Genomic analysis of relapse leukemic clones has also been useful detect‐

be the first leukemogenic event in these children [178,183].

218 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

and *CRLF2* overexpression in 62% of cases [192].

phorylation in primary B-cell progenitors [183,189,193].

**7. Conclusions**

To CONACyT FONSEC SSA/IMSS/ISSSTE//44402. (PPV) and CONACyT PhD grant 165427 (RJV).

## **Author details**

M.R. Juárez-Velázquez1 , C. Salas-Labadía1 , A. Reyes-León1 , M.P. Navarrete-Meneses1 , E.M. Fuentes-Pananá2 and P. Pérez-Vera1

1 Tissue Culture Laboratory, Department of Research in Human Genetics, National Pedia‐ trics Institute, Secretariat of Health, Mexico City, Mexico

2 Unit of Medical Research in Infectious and Parasitic Diseases, High Specialty Medical Care Unit of the Pediatric Hospital, National Medical Center XXI Century, Mexican Institute of Social Security, Mexico City, Mexico

## **References**


[4] Pui C-H, Carroll WL, Meshinchi S, Arceci RJ. Biology, risk stratification, and therapy of pediatric acute leukemias: an update. J. Clin. Oncol. 2011 Feb 10;29(5):551–65.

[18] Peschon JJ, Morrissey PJ, Grabstein KH, Ramsdell FJ, Maraskovsky E, Gliniak BC, et al. Early lymphocyte expansion is severely impaired in interleukin 7 receptor-defi‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

221

[19] von Freeden-Jeffry U, Vieira P, Lucian LA, McNeil T, Burdach SE, Murray R. Lym‐ phopenia in interleukin (IL)-7 gene-deleted mice identifies IL-7 as a nonredundant

[20] Cao X, Shores EW, Hu-Li J, Anver MR, Kelsall BL, Russell SM, et al. Defective lym‐ phoid development in mice lacking expression of the common cytokine receptor

[21] DiSanto JP, Müller W, Guy-Grand D, Fischer A, Rajewsky K. Lymphoid develop‐ ment in mice with a targeted deletion of the interleukin 2 receptor gamma chain.

[22] Kovanen PE, Leonard WJ. Cytokines and immunodeficiency diseases: critical roles of the gamma(c)-dependent cytokines interleukins 2, 4, 7, 9, 15, and 21, and their signal‐

[23] Hennighausen L, Robinson GW. Interpretation of cytokine signaling through the transcription factors STAT5A and STAT5B. Genes Dev. 2008 Mar 15;22(6):711–21.

[24] Ramadani F, Bolland DJ, Garcon F, Emery JL, Vanhaesebroeck B, Corcoran AE, et al. The PI3K isoforms p110alpha and p110delta are essential for pre-B cell receptor sig‐

[25] Marshall AJ, Fleming HE, Wu GE, Paige CJ. Modulation of the IL-7 dose-response threshold during pro-B cell differentiation is dependent on pre-B cell receptor ex‐

[26] Cobaleda C, Schebesta A, Delogu A, Busslinger M. Pax5: the guardian of B cell iden‐

[27] Nutt SL, Kee BL. The transcriptional regulation of B cell lineage commitment. Im‐

[28] Nutt SL, Heavey B, Rolink AG, Busslinger M. Commitment to the B-lymphoid line‐ age depends on the transcription factor Pax5. Nature. 1999 Oct 7;401(6753):556–62.

[29] Smith E, Sigvardsson M. The roles of transcription factors in B lymphocyte commit‐ ment, development, and transformation. J. Leukoc. Biol. 2004 Jun;75(6):973–81.

[30] O'Riordan M, Grosschedl R. Coordinate regulation of B cell differentiation by the

[31] Sato H, Saito-Ohara F, Inazawa J, Kudo A. Pax-5 is essential for kappa sterile tran‐ scription during Ig kappa chain gene rearrangement. J. Immunol. 2004 Apr 15;172(8):

transcription factors EBF and E2A. Immunity. 1999 Jul;11(1):21–31.

cient mice. J. Exp. Med. 1994 Nov 1;180(5):1955–60.

cytokine. J. Exp. Med. 1995 Apr 1;181(4):1519–26.

gamma chain. Immunity. 1995 Mar;2(3):223–38.

Proc. Natl. Acad. Sci. U.S.A. 1995 Jan 17;92(2):377–81.

ing pathways. Immunol. Rev. 2004 Dec;202:67–83.

pression. J. Immunol. 1998 Dec 1;161(11):6038–45.

munity. 2007 Jun;26(6):715–25.

4858–65.

tity and function. Nat. Immunol. 2007 May;8(5):463–70.

naling and B cell development. Sci Signal. 2010;3(134):ra60.


[18] Peschon JJ, Morrissey PJ, Grabstein KH, Ramsdell FJ, Maraskovsky E, Gliniak BC, et al. Early lymphocyte expansion is severely impaired in interleukin 7 receptor-defi‐ cient mice. J. Exp. Med. 1994 Nov 1;180(5):1955–60.

[4] Pui C-H, Carroll WL, Meshinchi S, Arceci RJ. Biology, risk stratification, and therapy of pediatric acute leukemias: an update. J. Clin. Oncol. 2011 Feb 10;29(5):551–65. [5] Neale GAM, Campana D, Pui C-H. Minimal residual disease detection in acute lym‐ phoblastic leukemia: real improvement with the real-time quantitative PCR method?

[6] Bhojwani D, Howard SC, Pui C-H. High-risk childhood acute lymphoblastic leuke‐

[7] Krivtsov AV, Armstrong SA. MLL translocations, histone modifications and leukae‐

[8] Pui CH, Crist WM, Look AT. Biology and clinical significance of cytogenetic abnor‐ malities in childhood acute lymphoblastic leukemia. Blood. 1990 Oct 15;76(8):1449–

[9] Greaves MF, Wiemels J. Origins of chromosome translocations in childhood leukae‐

[10] Pérez-Vera P, Reyes-León A, Fuentes-Pananá EM. Signaling proteins and transcrip‐ tion factors in normal and malignant early B cell development. Bone Marrow Res.

[11] Richie Ehrlich LI, Serwold T, Weissman IL. In vitro assays misrepresent in vivo line‐ age potentials of murine lymphoid progenitors. Blood. 2011 Mar 3;117(9):2618–24. [12] Schlenner SM, Madan V, Busch K, Tietz A, Läufle C, Costa C, et al. Fate mapping re‐ veals separate origins of T cells and myeloid lineages in the thymus. Immunity. 2010

[13] Fuentes-Pananá EM, Bannish G, Karnell FG, Treml JF, Monroe JG. Analysis of the in‐ dividual contributions of Igalpha (CD79a)- and Igbeta (CD79b)-mediated tonic sig‐ naling for bone marrow B cell development and peripheral B cell maturation. J.

[14] Fuentes-Pananá EM, Bannish G, Monroe JG. Basal B-cell receptor signaling in B lym‐ phocytes: mechanisms of regulation and role in positive selection, differentiation,

[15] van Grotel M, Meijerink JPP, Beverloo HB, Langerak AW, Buys-Gladdines JGCAM, Schneider P, et al. The outcome of molecular-cytogenetic subgroups in pediatric Tcell acute lymphoblastic leukemia: a retrospective study of patients treated according

[16] Noguchi M, Nakamura Y, Russell SM, Ziegler SF, Tsang M, Cao X, et al. Interleu‐ kin-2 receptor gamma chain: a functional component of the interleukin-7 receptor.

[17] Milne CD, Paige CJ. IL-7: a key regulator of B lymphopoiesis. Semin. Immunol. 2006

to DCOG or COALL protocols. Haematologica. 2006 Sep;91(9):1212–21.

and peripheral survival. Immunol. Rev. 2004 Feb;197:26–40.

mia stem-cell development. Nat. Rev. Cancer. 2007 Nov;7(11):823–33.

J. Pediatr. Hematol. Oncol. 2003 Feb;25(2):100–2.

220 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

mia. Nat. Rev. Cancer. 2003 Sep;3(9):639–49.

63.

2011;2011:502751.

Mar 26;32(3):426–36.

Immunol. 2006 Dec 1;177(11):7913–22.

Science. 1993 Dec 17;262(5141):1877–80.

Feb;18(1):20–30.

mia. Clin Lymphoma Myeloma. 2009;9 Suppl 3:S222–230.


[32] Fuxa M, Skok J, Souabni A, Salvagiotto G, Roldan E, Busslinger M. Pax5 induces Vto-DJ rearrangements and locus contraction of the immunoglobulin heavy-chain gene. Genes Dev. 2004 Feb 15;18(4):411–22.

[46] Szczepański T, Orfão A, van der Velden VH, San Miguel JF, van Dongen JJ. Minimal residual disease in leukaemia patients. Lancet Oncol. 2001 Jul;2(7):409–17.

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

223

[47] Campana D. Status of minimal residual disease testing in childhood haematological

[48] Campana D. Determination of minimal residual disease in leukaemia patients. Br. J.

[49] Campana D, Coustan-Smith E. Detection of minimal residual disease in acute leuke‐

[50] Gabert J, Beillard E, van der Velden VHJ, Bi W, Grimwade D, Pallisgaard N, et al. Standardization and quality control studies of "real-time" quantitative reverse tran‐ scriptase polymerase chain reaction of fusion gene transcripts for residual disease de‐ tection in leukemia - a Europe Against Cancer program. Leukemia. 2003 Dec;17(12):

[51] Campana D. Minimal residual disease in acute lymphoblastic leukemia. Semin.

[52] van der Velden VHJ, Hochhaus A, Cazzaniga G, Szczepanski T, Gabert J, van Don‐ gen JJM. Detection of minimal residual disease in hematologic malignancies by realtime quantitative PCR: principles, approaches, and laboratory aspects. Leukemia.

[53] Flohr T, Schrauder A, Cazzaniga G, Panzer-Grümayer R, van der Velden V, Fischer S, et al. Minimal residual disease-directed risk stratification using real-time quantita‐ tive PCR analysis of immunoglobulin and T-cell receptor gene rearrangements in the international multicenter trial AIEOP-BFM ALL 2000 for childhood acute lympho‐

[54] Coustan-Smith E, Sancho J, Hancock ML, Boyett JM, Behm FG, Raimondi SC, et al. Clinical importance of minimal residual disease in childhood acute lymphoblastic

[55] Coustan-Smith E, Behm FG, Sanchez J, Boyett JM, Hancock ML, Raimondi SC, et al. Immunological detection of minimalresidual disease in children with acute lympho‐

[56] Borowitz MJ, Devidas M, Hunger SP, Bowman WP, Carroll AJ, Carroll WL, et al. Clinical significance of minimal residual disease in childhood acute lymphoblastic leukemia and its relationship to other prognostic factors: a Children's Oncology

[57] Zhou J, Goldwasser MA, Li A, Dahlberg SE, Neuberg D, Wang H, et al. Quantitative analysis of minimal residual disease predicts relapse in children with B-lineage acute lymphoblastic leukemia in DFCI ALL Consortium Protocol 95-01. Blood. 2007 Sep

malignancies. Br. J. Haematol. 2008 Nov;143(4):481–9.

blastic leukemia. Leukemia. 2008 Apr;22(4):771–82.

blastic leukaemia. Lancet. 1998 Feb 21;351(9102):550–4.

Group study. Blood. 2008 Jun 15;111(12):5477–85.

leukemia. Blood. 2000 Oct 15;96(8):2691–6.

mia by flow cytometry. Cytometry. 1999 Aug 15;38(4):139–52.

Haematol. 2003 Jun;121(6):823–38.

Hematol. 2009 Jan;46(1):100–6.

2003 Jun;17(6):1013–34.

1;110(5):1607–11.

2318–57.


[46] Szczepański T, Orfão A, van der Velden VH, San Miguel JF, van Dongen JJ. Minimal residual disease in leukaemia patients. Lancet Oncol. 2001 Jul;2(7):409–17.

[32] Fuxa M, Skok J, Souabni A, Salvagiotto G, Roldan E, Busslinger M. Pax5 induces Vto-DJ rearrangements and locus contraction of the immunoglobulin heavy-chain

[33] Kuo TC, Schlissel MS. Mechanisms controlling expression of the RAG locus during

[34] Bain G, Maandag EC, Izon DJ, Amsen D, Kruisbeek AM, Weintraub BC, et al. E2A proteins are required for proper B cell development and initiation of immunoglobu‐

[35] Graux C, Cools J, Michaux L, Vandenberghe P, Hagemeijer A. Cytogenetics and mo‐ lecular genetics of T-cell acute lymphoblastic leukemia: from thymocyte to lympho‐

[36] Van Vlierberghe P, Pieters R, Beverloo HB, Meijerink JPP. Molecular-genetic insights in paediatric T-cell acute lymphoblastic leukaemia. Br. J. Haematol. 2008 Oct;143(2):

[37] De Keersmaecker K, Marynen P, Cools J. Genetic insights in the pathogenesis of Tcell acute lymphoblastic leukemia. Haematologica. 2005 Aug;90(8):1116–27.

[38] Koch U, Radtke F. Mechanisms of T cell development and transformation. Annu.

[39] Ikawa T, Hirose S, Masuda K, Kakugawa K, Satoh R, Shibano-Satoh A, et al. An es‐ sential developmental checkpoint for production of the T cell lineage. Science. 2010

[40] Riz I, Hawley TS, Johnston H, Hawley RG. Role of TLX1 in T-cell acute lymphoblas‐

[41] Dördelmann M, Reiter A, Borkhardt A, Ludwig WD, Götz N, Viehmann S, et al. Pre‐ dnisone response is the strongest predictor of treatment outcome in infant acute lym‐

[42] Pui C-H. Recent research advances in childhood acute lymphoblastic leukemia. J.

[43] Manabe A, Ohara A, Hasegawa D, Koh K, Saito T, Kiyokawa N, et al. Significance of the complete clearance of peripheral blasts after 7 days of prednisolone treatment in children with acute lymphoblastic leukemia: the Tokyo Children's Cancer Study

[44] Pui CH, Campana D, Evans WE. Childhood acute lymphoblastic leukaemia--current

[45] Aricò M, Valsecchi MG, Conter V, Rizzari C, Pession A, Messina C, et al. Improved outcome in high-risk childhood acute lymphoblastic leukemia defined by predni‐ sone-poor response treated with double Berlin-Frankfurt-Muenster protocol II.

tic leukaemia pathogenesis. Br. J. Haematol. 2009 Apr;145(1):140–3.

phoblastic leukemia. Blood. 1999 Aug 15;94(4):1209–17.

Group Study L99-15. Haematologica. 2008 Aug;93(8):1155–60.

status and future perspectives. Lancet Oncol. 2001 Oct;2(10):597–607.

Formos. Med. Assoc. 2010 Nov;109(11):777–87.

Blood. 2002 Jul 15;100(2):420–6.

lymphocyte development. Curr. Opin. Immunol. 2009 Apr;21(2):173–8.

gene. Genes Dev. 2004 Feb 15;18(4):411–22.

222 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

blast. Leukemia. 2006 Sep;20(9):1496–510.

Rev. Cell Dev. Biol. 2011 Nov 10;27:539–62.

153–68.

Jul 2;329(5987):93–6.

lin gene rearrangements. Cell. 1994 Dec 2;79(5):885–92.


[58] Basso G, Veltroni M, Valsecchi MG, Dworzak MN, Ratei R, Silvestri D, et al. Risk of relapse of childhood acute lymphoblastic leukemia is predicted by flow cytometric measurement of residual disease on day 15 bone marrow. J. Clin. Oncol. 2009 Nov 1;27(31):5168–74.

[72] Nahar R, Ramezani-Rad P, Mossner M, Duy C, Cerchietti L, Geng H, et al. Pre-B cell receptor-mediated activation of BCL6 induces pre-B cell quiescence through tran‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

225

[73] Skorski T. Genomic instability: The cause and effect of BCR/ABL tyrosine kinase.

[74] Pui C-H, Evans WE. Treatment of acute lymphoblastic leukemia. N. Engl. J. Med.

[75] Pieters R, Carroll WL. Biology and treatment of acute lymphoblastic leukemia. Hem‐

[76] Szczepański T, Harrison CJ, van Dongen JJM. Genetic aberrations in paediatric acute leukaemias and implications for management of patients. Lancet Oncol. 2010 Sep;

[77] Moorman AV, Ensor HM, Richards SM, Chilton L, Schwab C, Kinsey SE, et al. Prog‐ nostic effect of chromosomal abnormalities in childhood B-cell precursor acute lym‐ phoblastic leukaemia: results from the UK Medical Research Council ALL97/99

[78] Schrappe M, Reiter A, Ludwig WD, Harbott J, Zimmermann M, Hiddemann W, et al. Improved outcome in childhood acute lymphoblastic leukemia despite reduced use of anthracyclines and cranial radiotherapy: results of trial ALL-BFM 90. German-

[79] Jiménez-Morales S, Miranda-Peralta E, Saldaña-Alvarez Y, Perez-Vera P, Paredes-Aguilera R, Rivera-Luna R, et al. BCR-ABL, ETV6-RUNX1 and E2A-PBX1: preva‐ lence of the most common acute lymphoblastic leukemia fusion genes in Mexican

[80] Borkhardt A, Cazzaniga G, Viehmann S, Valsecchi MG, Ludwig WD, Burci L, et al. Incidence and clinical relevance of TEL/AML1 fusion genes in children with acute lymphoblastic leukemia enrolled in the German and Italian multicenter therapy tri‐ als. Associazione Italiana Ematologia Oncologia Pediatrica and the Berlin-Frankfurt-

[81] Harrison CJ, Moorman AV, Barber KE, Broadfield ZJ, Cheung KL, Harris RL, et al. Interphase molecular cytogenetic screening for chromosomal abnormalities of prog‐ nostic significance in childhood acute lymphoblastic leukaemia: a UK Cancer Cyto‐

[82] Pui C-H, Robison LL, Look AT. Acute lymphoblastic leukaemia. Lancet. 2008 Mar

[83] Aldrich MC, Zhang L, Wiemels JL, Ma X, Loh ML, Metayer C, et al. Cytogenetics of Hispanic and White children with acute lymphoblastic leukemia in California. Can‐

Austrian-Swiss ALL-BFM Study Group. Blood. 2000 Jun 1;95(11):3310–22.

scriptional repression of MYC. Blood. 2011 Oct 13;118(15):4174–8.

Curr Hematol Malig Rep. 2007 May;2(2):69–74.

atol. Oncol. Clin. North Am. 2010 Feb;24(1):1–18.

randomised trial. Lancet Oncol. 2010 May;11(5):429–38.

patients. Leuk. Res. 2008 Oct;32(10):1518–22.

22;371(9617):1030–43.

Münster Study Group. Blood. 1997 Jul 15;90(2):571–7.

genetics Group Study. Br. J. Haematol. 2005 May;129(4):520–30.

cer Epidemiol. Biomarkers Prev. 2006 Mar;15(3):578–81.

2006 Jan 12;354(2):166–78.

11(9):880–9.


[72] Nahar R, Ramezani-Rad P, Mossner M, Duy C, Cerchietti L, Geng H, et al. Pre-B cell receptor-mediated activation of BCL6 induces pre-B cell quiescence through tran‐ scriptional repression of MYC. Blood. 2011 Oct 13;118(15):4174–8.

[58] Basso G, Veltroni M, Valsecchi MG, Dworzak MN, Ratei R, Silvestri D, et al. Risk of relapse of childhood acute lymphoblastic leukemia is predicted by flow cytometric measurement of residual disease on day 15 bone marrow. J. Clin. Oncol. 2009 Nov

[59] Eckert C, Biondi A, Seeger K, Cazzaniga G, Hartmann R, Beyermann B, et al. Prog‐ nostic value of minimal residual disease in relapsed childhood acute lymphoblastic

[60] Coustan-Smith E, Gajjar A, Hijiya N, Razzouk BI, Ribeiro RC, Rivera GK, et al. Clini‐ cal significance of minimal residual disease in childhood acute lymphoblastic leuke‐

[61] Pfeiffer P, Goedecke W, Obe G. Mechanisms of DNA double-strand break repair and their potential to induce chromosomal aberrations. Mutagenesis. 2000 Jul;15(4):289–

[62] Greaves M. In utero origins of childhood leukaemia. Early Hum. Dev. 2005 Jan;81(1):

[63] Chen Z, Sandberg AA. Molecular cytogenetic aspects of hematological malignancies:

[64] Mrózek K, Harper DP, Aplan PD. Cytogenetics and molecular genetics of acute lym‐ phoblastic leukemia. Hematol. Oncol. Clin. North Am. 2009 Oct;23(5):991–1010. [65] Heisterkamp N, Stam K, Groffen J, de Klein A, Grosveld G. Structural organization of the bcr gene and its role in the Ph' translocation. Nature. 1985 Jul 27;315(6022):758–

[66] Barilá D, Superti-Furga G. An intramolecular SH3-domain interaction regulates c-Abl

[67] Chissoe SL, Bodenteich A, Wang YF, Wang YP, Burian D, Clifton SW, et al. Sequence and analysis of the human ABL gene, the BCR gene, and regions involved in the Phil‐

[68] Fröhling S, Döhner H. Chromosomal abnormalities in cancer. N. Engl. J. Med. 2008

[69] Chalandon Y, Schwaller J. Targeting mutated protein tyrosine kinases and their sig‐ naling pathways in hematologic malignancies. Haematologica. 2005 Jul;90(7):949–68.

[70] van Dongen JJ, Macintyre EA, Gabert JA, Delabesse E, Rossi V, Saglio G, et al. Stand‐ ardized RT-PCR analysis of fusion gene transcripts from chromosome aberrations in acute leukemia for detection of minimal residual disease. Report of the BIOMED-1 Concerted Action: investigation of minimal residual disease in acute leukemia. Leu‐

[71] Raimondi SC, Roberson PK, Pui CH, Behm FG, Rivera GK. Hyperdiploid (47-50) acute lymphoblastic leukemia in children. Blood. 1992 Jun 15;79(12):3245–52.

adelphia chromosomal translocation. Genomics. 1995 May 1;27(1):67–82.

clinical implications. Am. J. Med. Genet. 2002 Oct 30;115(3):130–41.

leukaemia. Lancet. 2001 Oct 13;358(9289):1239–41.

224 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

activity. Nat. Genet. 1998 Mar;18(3):280–2.

Aug 14;359(7):722–34.

kemia. 1999 Dec;13(12):1901–28.

mia after first relapse. Leukemia. 2004 Mar;18(3):499–504.

1;27(31):5168–74.

302.

123–9.

61.


[84] Pérez-Vera P, Salas C, Montero-Ruiz O, Frías S, Dehesa G, Jarquín B, et al. Analysis of gene rearrangements using a fluorescence in situ hybridization method in Mexi‐ can patients with acute lymphoblastic leukemia: experience at a single institution. Cancer Genet. Cytogenet. 2008 Jul 15;184(2):94–8.

[97] Pui C-H, Sandlund JT, Pei D, Campana D, Rivera GK, Ribeiro RC, et al. Improved outcome for children with acute lymphoblastic leukemia: results of Total Therapy Study XIIIB at St Jude Children's Research Hospital. Blood. 2004 Nov 1;104(9):2690–

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

227

[98] Privitera E, Kamps MP, Hayashi Y, Inaba T, Shapiro LH, Raimondi SC, et al. Differ‐ ent molecular consequences of the 1;19 chromosomal translocation in childhood B-

[99] Crist WM, Carroll AJ, Shuster JJ, Behm FG, Whitehead M, Vietti TJ, et al. Poor prog‐ nosis of children with pre-B acute lymphoblastic leukemia is associated with the t(1;19)(q23;p13): a Pediatric Oncology Group study. Blood. 1990 Jul 1;76(1):117–22.

[100] Inaba T, Inukai T, Yoshihara T, Seyschab H, Ashmun RA, Canman CE, et al. Reversal of apoptosis by the leukaemia-associated E2A-HLF chimaeric transcription factor.

[101] Harper DP, Aplan PD. Chromosomal rearrangements leading to MLL gene fusions:

[102] Slany RK. The molecular biology of mixed lineage leukemia. Haematologica. 2009

[103] Liu H, Takeda S, Kumar R, Westergard TD, Brown EJ, Pandita TK, et al. Phosphory‐ lation of MLL by ATR is required for execution of mammalian S-phase checkpoint.

[104] Sung PA, Libura J, Richardson C. Etoposide and illegitimate DNA double-strand break repair in the generation of MLL translocations: new insights and new ques‐

[105] Chuk MK, McIntyre E, Small D, Brown P. Discordance of MLL-rearranged (MLL-R) infant acute lymphoblastic leukemia in monozygotic twins with spontaneous clear‐ ance of preleukemic clone in unaffected twin. Blood. 2009 Jun 25;113(26):6691–4.

[106] Alexander FE, Patheal SL, Biondi A, Brandalise S, Cabrera ME, Chan LC, et al. Trans‐ placental chemical exposure and risk of infant leukemia with MLL gene fusion. Can‐

[107] Bueno C, Catalina P, Melen GJ, Montes R, Sánchez L, Ligero G, et al. Etoposide indu‐ ces MLL rearrangements and other chromosomal abnormalities in human embryonic

[108] Schnyder S, Du NT, Le HB, Singh S, Loredo GA, Vaughan AT. Estrogen treatment induces MLL aberrations in human lymphoblastoid cells. Leuk. Res. 2009 Oct;33(10):

[109] Blanco JG, Edick MJ, Relling MV. Etoposide induces chimeric Mll gene fusions. FA‐

clinical and biological aspects. Cancer Res. 2008 Dec 15;68(24):10024–7.

Nature. 1996 Aug 8;382(6591):541–4.

Nature. 2010 Sep 16;467(7313):343–6.

cer Res. 2001 Mar 15;61(6):2542–6.

SEB J. 2004 Jan;18(1):173–5.

1400–4.

tions. DNA Repair (Amst.). 2006 Sep 8;5(9-10):1109–18.

stem cells. Carcinogenesis. 2009 Sep;30(9):1628–37.

Jul;94(7):984–93.

cell precursor acute lymphoblastic leukemia. Blood. 1992 Apr 1;79(7):1781–8.

6.


[97] Pui C-H, Sandlund JT, Pei D, Campana D, Rivera GK, Ribeiro RC, et al. Improved outcome for children with acute lymphoblastic leukemia: results of Total Therapy Study XIIIB at St Jude Children's Research Hospital. Blood. 2004 Nov 1;104(9):2690– 6.

[84] Pérez-Vera P, Salas C, Montero-Ruiz O, Frías S, Dehesa G, Jarquín B, et al. Analysis of gene rearrangements using a fluorescence in situ hybridization method in Mexi‐ can patients with acute lymphoblastic leukemia: experience at a single institution.

[85] Chen B, Wang Y-Y, Shen Y, Zhang W-N, He H-Y, Zhu Y-M, et al. Newly diagnosed acute lymphoblastic leukemia in China (I): abnormal genetic patterns in 1346 child‐ hood and adult cases and their comparison with the reports from Western countries.

[86] Ariffin H, Chen S-P, Kwok CS, Quah T-C, Lin H-P, Yeoh AEJ. Ethnic differences in the frequency of subtypes of childhood acute lymphoblastic leukemia: results of the Malaysia-Singapore Leukemia Study Group. J. Pediatr. Hematol. Oncol. 2007 Jan;

[87] Hunger SP. Tyrosine kinase inhibitor use in pediatric Philadelphia chromosome-pos‐ itive acute lymphoblastic anemia. Hematology Am Soc Hematol Educ Program.

[88] Nourse J, Mellentin JD, Galili N, Wilkinson J, Stanbridge E, Smith SD, et al. Chromo‐ somal translocation t(1;19) results in synthesis of a homeobox fusion mRNA that co‐ des for a potential chimeric transcription factor. Cell. 1990 Feb 23;60(4):535–45. [89] Biondi A, Masera G. Molecular pathogenesis of childhood acute lymphoblastic leu‐

[90] Chan KK-K, Zhang J, Chia N-Y, Chan Y-S, Sim HS, Tan KS, et al. KLF4 and PBX1 di‐ rectly regulate NANOG expression in human embryonic stem cells. Stem Cells. 2009

[91] LeBrun DP. E2A basic helix-loop-helix transcription factors in human leukemia.

[92] Look AT. Oncogenic transcription factors in the human acute leukemias. Science.

[93] Graham DK, Salzberg DB, Kurtzberg J, Sather S, Matsushima GK, Keating AK, et al. Ectopic expression of the proto-oncogene Mer in pediatric T-cell acute lymphoblastic

[94] Shiozawa Y, Pedersen EA, Taichman RS. GAS6/Mer axis regulates the homing and survival of the E2A/PBX1-positive B-cell precursor acute lymphoblastic leukemia in

[95] Armstrong SA, Look AT. Molecular genetics of acute lymphoblastic leukemia. J. Clin.

[96] Iacobucci I, Papayannidis C, Lonetti A, Ferrari A, Baccarani M, Martinelli G. Cytoge‐ netic and molecular predictors of outcome in acute lymphocytic leukemia: recent de‐

Cancer Genet. Cytogenet. 2008 Jul 15;184(2):94–8.

226 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Leukemia. 2012 Jul;26(7):1608–16.

kemia. Haematologica. 1998 Jul;83(7):651–9.

Front. Biosci. 2003 May 1;8:s206–222.

leukemia. Clin. Cancer Res. 2006 May 1;12(9):2662–9.

the bone marrow niche. Exp. Hematol. 2010 Feb;38(2):132–40.

velopments. Curr Hematol Malig Rep. 2012 Jun;7(2):133–43.

1997 Nov 7;278(5340):1059–64.

Oncol. 2005 Sep 10;23(26):6306–15.

29(1):27–31.

2011;2011:361–5.

Sep;27(9):2114–25.


[110] Barjesteh van Waalwijk van Doorn-Khosrovani S, Janssen J, Maas LM, Godschalk RWL, Nijhuis JG, van Schooten FJ. Dietary flavonoids induce MLL translocations in primary human CD34+ cells. Carcinogenesis. 2007 Aug;28(8):1703–9.

[122] Siraj AK, Kamat S, Gutiérrez MI, Banavali S, Timpson G, Sazawal S, et al. Frequen‐ cies of the major subgroups of precursor B-cell acute lymphoblastic leukemia in Indi‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

229

[123] Liang D-C, Shih L-Y, Yang C-P, Hung I-J, Liu H-C, Jaing T-H, et al. Frequencies of ETV6-RUNX1 fusion and hyperdiploidy in pediatric acute lymphoblastic leukemia

[124] Seeger K, Adams HP, Buchwald D, Beyermann B, Kremens B, Niemeyer C, et al. TEL-AML1 fusion transcript in relapsed childhood acute lymphoblastic leukemia.

The Berlin-Frankfurt-Münster Study Group. Blood. 1998 Mar 1;91(5):1716–22. [125] van Delft FW, Horsley S, Colman S, Anderson K, Bateman C, Kempski H, et al. Clo‐ nal origins of relapse in ETV6-RUNX1 acute lymphoblastic leukemia. Blood. 2011 Jun

[126] Kuster L, Grausenburger R, Fuka G, Kaindl U, Krapf G, Inthal A, et al. ETV6/ RUNX1-positive relapses evolve from an ancestral clone and frequently acquire dele‐ tions of genes implicated in glucocorticoid signaling. Blood. 2011 Mar 3;117(9):2658–

[127] Paulsson K, Forestier E, Lilljebjörn H, Heldrup J, Behrendtz M, Young BD, et al. Ge‐ netic landscape of high hyperdiploid childhood acute lymphoblastic leukemia. Proc.

[128] Pui CH, Raimondi SC, Williams DL. Isochromosome 17q in childhood acute lympho‐ blastic leukemia: an adverse cytogenetic feature in association with hyperdiploidy?

[129] Harris MB, Shuster JJ, Carroll A, Look AT, Borowitz MJ, Crist WM, et al. Trisomy of leukemic cell chromosomes 4 and 10 identifies children with B-progenitor cell acute lymphoblastic leukemia with a very low risk of treatment failure: a Pediatric Oncolo‐

[130] Heerema NA, Sather HN, Sensel MG, Zhang T, Hutchinson RJ, Nachman JB, et al. Prognostic impact of trisomies of chromosomes 10, 17, and 5 among children with acute lymphoblastic leukemia and high hyperdiploidy (> 50 chromosomes). J. Clin.

[131] Moorman AV, Richards SM, Martineau M, Cheung KL, Robinson HM, Jalali GR, et al. Outcome heterogeneity in childhood high-hyperdiploid acute lymphoblastic leu‐

[132] Sutcliffe MJ, Shuster JJ, Sather HN, Camitta BM, Pullen J, Schultz KR, et al. High con‐ cordance from independent studies by the Children's Cancer Group (CCG) and Pe‐ diatric Oncology Group (POG) associating favorable prognosis with combined trisomies 4, 10, and 17 in children with NCI Standard-Risk B-precursor Acute Lym‐ phoblastic Leukemia: a Children's Oncology Group (COG) initiative. Leukemia. 2005

Natl. Acad. Sci. U.S.A. 2010 Dec 14;107(50):21719–24.

gy Group study. Blood. 1992 Jun 15;79(12):3316–24.

Leukemia. 1988 Apr;2(4):222–5.

Oncol. 2000 May;18(9):1876–87.

May;19(5):734–40.

kemia. Blood. 2003 Oct 15;102(8):2756–62.

are lower in far east than west. Pediatr Blood Cancer. 2010 Sep;55(3):430–3.

an children differ from the West. Leukemia. 2003 Jun;17(6):1192–3.

9;117(23):6247–54.

67.


[122] Siraj AK, Kamat S, Gutiérrez MI, Banavali S, Timpson G, Sazawal S, et al. Frequen‐ cies of the major subgroups of precursor B-cell acute lymphoblastic leukemia in Indi‐ an children differ from the West. Leukemia. 2003 Jun;17(6):1192–3.

[110] Barjesteh van Waalwijk van Doorn-Khosrovani S, Janssen J, Maas LM, Godschalk RWL, Nijhuis JG, van Schooten FJ. Dietary flavonoids induce MLL translocations in

[111] Rojas E, Mussali P, Tovar E, Valverde M. DNA-AP sites generation by etoposide in

[112] Moneypenny CG, Shao J, Song Y, Gallagher EP. MLL rearrangements are induced by low doses of etoposide in human fetal hematopoietic stem cells. Carcinogenesis. 2006

[113] Brassesco MS, Montaldi AP, Gras DE, Camparoto ML, Martinez-Rossi NM, Scrideli CA, et al. Cytogenetic and molecular analysis of MLL rearrangements in acute lym‐

[114] Montero-Ruíz O, Alcántara-Ortigoza MA, Betancourt M, Juárez-Velázquez R, Gonzá‐ lez-Márquez H, Pérez-Vera P. Expression of RUNX1 isoforms and its target gene BLK in childhood acute lymphoblastic leukemia. Leuk. Res. 2012 Sep;36(9):1105–11.

[115] Roudaia L, Cheney MD, Manuylova E, Chen W, Morrow M, Park S, et al. CBFbeta is critical for AML1-ETO and TEL-AML1 activity. Blood. 2009 Mar 26;113(13):3070–9.

[116] De Braekeleer E, Douet-Guilbert N, Morel F, Le Bris M-J, Basinko A, De Braekeleer M. ETV6 fusion genes in hematological malignancies: A review. Leuk. Res. 2012 Aug;

[117] Wiemels JL, Hofmann J, Kang M, Selzer R, Green R, Zhou M, et al. Chromosome 12p deletions in TEL-AML1 childhood acute lymphoblastic leukemia are associated with retrotransposon elements and occur postnatally. Cancer Res. 2008 Dec 1;68(23):9935–

[118] Shurtleff SA, Buijs A, Behm FG, Rubnitz JE, Raimondi SC, Hancock ML, et al. TEL/ AML1 fusion resulting from a cryptic t(12;21) is the most common genetic lesion in pediatric ALL and defines a subgroup of patients with an excellent prognosis. Leuke‐

[119] Loh ML, Goldwasser MA, Silverman LB, Poon W-M, Vattikuti S, Cardoso A, et al. Prospective analysis of TEL/AML1-positive patients treated on Dana-Farber Cancer

[120] Rubnitz JE, Downing JR, Pui CH, Shurtleff SA, Raimondi SC, Evans WE, et al. TEL gene rearrangement in acute lymphoblastic leukemia: a new genetic marker with

[121] Pérez-Vera P, Montero-Ruiz O, Frías S, Ulloa-Avilés V, Cárdenas-Cardós R, Paredes-Aguilera R, et al. Detection of ETV6 and RUNX1 gene rearrangements using fluores‐ cence in situ hybridization in Mexican patients with acute lymphoblastic leukemia: experience at a single institution. Cancer Genet. Cytogenet. 2005 Oct 15;162(2):140–5.

Institute Consortium Protocol 95-01. Blood. 2006 Jun 1;107(11):4508–13.

prognostic significance. J. Clin. Oncol. 1997 Mar;15(3):1150–7.

phoblastic leukaemia survivors. Mutagenesis. 2009 Mar;24(2):153–60.

primary human CD34+ cells. Carcinogenesis. 2007 Aug;28(8):1703–9.

whole blood cells. BMC Cancer. 2009;9:398.

228 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Apr;27(4):874–81.

36(8):945–61.

mia. 1995 Dec;9(12):1985–9.

44.


[133] Treviño LR, Yang W, French D, Hunger SP, Carroll WL, Devidas M, et al. Germline genomic variants associated with childhood acute lymphoblastic leukemia. Nat. Gen‐ et. 2009 Sep;41(9):1001–5.

[144] Asnafi V, Beldjord K, Libura M, Villarese P, Millien C, Ballerini P, et al. Age-related phenotypic and oncogenic differences in T-cell acute lymphoblastic leukemias may

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

231

[145] 145. De Keersmaecker K, Real PJ, Gatta GD, Palomero T, Sulis ML, Tosello V, et al. The TLX1 oncogene drives aneuploidy in T cell transformation. Nat. Med. 2010 Nov;

[146] O'Neil J, Shank J, Cusson N, Murre C, Kelliher M. TAL1/SCL induces leukemia by inhibiting the transcriptional activity of E47/HEB. Cancer Cell. 2004 Jun;5(6):587–96.

[147] Mansur MB, Hassan R, Barbosa TC, Splendore A, Jotta PY, Yunes JA, et al. Impact of complex NOTCH1 mutations on survival in paediatric T-cell leukaemia. BMC Can‐

[148] Mansur MB, Emerenciano M, Brewer L, Sant'Ana M, Mendonça N, Thuler LCS, et al. SIL-TAL1 fusion gene negative impact in T-cell acute lymphoblastic leukemia out‐

[149] Real PJ, Tosello V, Palomero T, Castillo M, Hernando E, de Stanchina E, et al. Gam‐ ma-secretase inhibitors reverse glucocorticoid resistance in T cell acute lymphoblastic

[150] Kittler R, Putz G, Pelletier L, Poser I, Heninger A-K, Drechsel D, et al. An endoribo‐ nuclease-prepared siRNA screen in human cells identifies genes essential for cell di‐

[151] Choi YH, Kim KB, Kim HH, Hong GS, Kwon YK, Chung CW, et al. FLASH coordi‐ nates NF-kappa B activity via TRAF2. J. Biol. Chem. 2001 Jul 6;276(27):25073–7.

[152] Jun J-I, Chung C-W, Lee H-J, Pyo J-O, Lee KN, Kim N-S, et al. Role of FLASH in cas‐ pase-8-mediated activation of NF-kappaB: dominant-negative function of FLASH

mutant in NF-kappaB signaling pathway. Oncogene. 2005 Jan 20;24(4):688–96.

[153] Alm-Kristiansen AH, Saether T, Matre V, Gilfillan S, Dahle O, Gabrielsen OS. FLASH acts as a co-activator of the transcription factor c-Myb and localizes to active RNA

[154] Alm-Kristiansen AH, Lorenzo PI, Molværsmyr A-K, Matre V, Ledsaak M, Sæther T, et al. PIAS1 interacts with FLASH and enhances its co-activation of c-Myb. Mol. Can‐

[155] Barcaroli D, Dinsdale D, Neale MH, Bongiorno-Borbone L, Ranalli M, Munarriz E, et al. FLASH is an essential component of Cajal bodies. Proc. Natl. Acad. Sci. U.S.A.

[156] Barcaroli D, Bongiorno-Borbone L, Terrinoni A, Hofmann TG, Rossi M, Knight RA, et al. FLASH is required for histone transcription and S-phase progression. Proc.

reflect thymic atrophy. Blood. 2004 Dec 15;104(13):4173–80.

come. Leuk. Lymphoma. 2009 Aug;50(8):1318–25.

leukemia. Nat. Med. 2009 Jan;15(1):50–8.

vision. Nature. 2004 Dec 23;432(7020):1036–40.

polymerase II foci. Oncogene. 2008 Aug 7;27(34):4644–56.

Natl. Acad. Sci. U.S.A. 2006 Oct 3;103(40):14808–12.

16(11):1321–7.

cer. 2012;12:9.

cer. 2011;10:21.

2006 Oct 3;103(40):14802–7.


[144] Asnafi V, Beldjord K, Libura M, Villarese P, Millien C, Ballerini P, et al. Age-related phenotypic and oncogenic differences in T-cell acute lymphoblastic leukemias may reflect thymic atrophy. Blood. 2004 Dec 15;104(13):4173–80.

[133] Treviño LR, Yang W, French D, Hunger SP, Carroll WL, Devidas M, et al. Germline genomic variants associated with childhood acute lymphoblastic leukemia. Nat. Gen‐

[134] Moorman AV, Harrison CJ, Buck GAN, Richards SM, Secker-Walker LM, Martineau M, et al. Karyotype is an independent prognostic factor in adult acute lymphoblastic leukemia (ALL): analysis of cytogenetic data from patients treated on the Medical Research Council (MRC) UKALLXII/Eastern Cooperative Oncology Group (ECOG)

[135] Raimondi SC, Zhou Y, Shurtleff SA, Rubnitz JE, Pui C-H, Behm FG. Near-triploidy and near-tetraploidy in childhood acute lymphoblastic leukemia: association with Blineage blast cells carrying the ETV6-RUNX1 fusion, T-lineage immunophenotype,

[136] Raimondi SC, Zhou Y, Mathew S, Shurtleff SA, Sandlund JT, Rivera GK, et al. Reas‐ sessment of the prognostic significance of hypodiploidy in pediatric patients with

[137] Cavé H, Suciu S, Preudhomme C, Poppe B, Robert A, Uyttebroeck A, et al. Clinical significance of HOX11L2 expression linked to t(5;14)(q35;q32), of HOX11 expression, and of SIL-TAL fusion in childhood T-cell malignancies: results of EORTC studies

[138] Zhu Y-M, Zhao W-L, Fu J-F, Shi J-Y, Pan Q, Hu J, et al. NOTCH1 mutations in T-cell acute lymphoblastic leukemia: prognostic significance and implication in multifacto‐

[139] van Grotel M, Meijerink JPP, van Wering ER, Langerak AW, Beverloo HB, Buijs-Gladdines JGCAM, et al. Prognostic significance of molecular-cytogenetic abnormali‐ ties in pediatric T-ALL is not explained by immunophenotypic differences.

[140] Ferrando AA, Neuberg DS, Staunton J, Loh ML, Huard C, Raimondi SC, et al. Gene expression signatures define novel oncogenic pathways in T cell acute lymphoblastic

[141] Ballerini P, Landman-Parker J, Cayuela JM, Asnafi V, Labopin M, Gandemer V, et al. Impact of genotype on survival of children with T-cell acute lymphoblastic leukemia treated according to the French protocol FRALLE-93: the effect of TLX3/HOX11L2

[142] Aifantis I, Raetz E, Buonamici S. Molecular pathogenesis of T-cell leukaemia and

[143] Bergeron J, Clappier E, Radford I, Buzyn A, Millien C, Soler G, et al. Prognostic and oncogenic relevance of TLX1/HOX11 expression level in T-ALLs. Blood. 2007 Oct

gene expression on outcome. Haematologica. 2008 Nov;93(11):1658–65.

lymphoma. Nat. Rev. Immunol. 2008 May;8(5):380–90.

and favorable outcome. Cancer Genet. Cytogenet. 2006 Aug;169(1):50–7.

acute lymphoblastic leukemia. Cancer. 2003 Dec 15;98(12):2715–22.

rial leukemogenesis. Clin. Cancer Res. 2006 May 15;12(10):3043–9.

et. 2009 Sep;41(9):1001–5.

2993 trial. Blood. 2007 Apr 15;109(8):3189–97.

230 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

58881 and 58951. Blood. 2004 Jan 15;103(2):442–50.

Leukemia. 2008 Jan;22(1):124–31.

1;110(7):2324–30.

leukemia. Cancer Cell. 2002 Feb;1(1):75–87.


[157] Yang X, Xu B, Sabath I, Kunduru L, Burch BD, Marzluff WF, et al. FLASH is required for the endonucleolytic cleavage of histone pre-mRNAs but is dispensable for the 5' exonucleolytic degradation of the downstream cleavage product. Mol. Cell. Biol. 2011 Apr;31(7):1492–502.

[169] Olivero S, Maroc C, Beillard E, Gabert J, Nietfeld W, Chabannon C, et al. Detection of different Ikaros isoforms in human leukaemias using real-time quantitative polymer‐

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

233

[170] Meleshko AN, Movchan LV, Belevtsev MV, Savitskaja TV. Relative expression of dif‐ ferent Ikaros isoforms in childhood acute leukemia. Blood Cells Mol. Dis. 2008 Dec;

[171] Ruiz A, Jiang J, Kempski H, Brady HJM. Overexpression of the Ikaros 6 isoform is restricted to t(4;11) acute lymphoblastic leukaemia in children and infants and has a

[172] Yang JJ, Bhojwani D, Yang W, Cai X, Stocco G, Crews K, et al. Genome-wide copy number profiling reveals molecular evolution from diagnosis to relapse in childhood

[173] Kuiper RP, Waanders E, van der Velden VHJ, van Reijmersdal SV, Venkatachalam R, Scheijen B, et al. IKZF1 deletions predict relapse in uniformly treated pediatric pre‐

[174] Waanders E, van der Velden VHJ, van der Schoot CE, van Leeuwen FN, van Reij‐ mersdal SV, de Haas V, et al. Integrated use of minimal residual disease classification and IKZF1 alteration status accurately predicts 79% of relapses in pediatric acute

[175] Den Boer ML, van Slegtenhorst M, De Menezes RX, Cheok MH, Buijs-Gladdines JGCAM, Peters STCJM, et al. A subtype of childhood acute lymphoblastic leukaemia with poor treatment outcome: a genome-wide classification study. Lancet Oncol.

[176] Pellegrini S, Dusanter-Fourt I. The structure, regulation and function of the Janus kinases (JAKs) and the signal transducers and activators of transcription (STATs).

[177] Rawlings JS, Rosler KM, Harrison DA. The JAK/STAT signaling pathway. J. Cell. Sci.

[178] Mullighan CG, Collins-Underwood JR, Phillips LAA, Loudin MG, Liu W, Zhang J, et al. Rearrangement of CRLF2 in B-progenitor- and Down syndrome-associated acute

[179] Bercovich D, Ganmore I, Scott LM, Wainreb G, Birger Y, Elimelech A, et al. Muta‐ tions of JAK2 in acute lymphoblastic leukaemias associated with Down's syndrome.

[180] Gaikwad A, Rye CL, Devidas M, Heerema NA, Carroll AJ, Izraeli S, et al. Prevalence and clinical correlates of JAK2 mutations in Down syndrome acute lymphoblastic

lymphoblastic leukemia. Nat. Genet. 2009 Nov;41(11):1243–6.

ase chain reaction. Br. J. Haematol. 2000 Sep;110(4):826–30.

role in B-cell survival. Br. J. Haematol. 2004 Apr;125(1):31–7.

cursor B-ALL. Leukemia. 2010 Jul;24(7):1258–64.

Eur. J. Biochem. 1997 Sep 15;248(3):615–33.

Lancet. 2008 Oct 25;372(9648):1484–92.

leukaemia. Br. J. Haematol. 2009 Mar;144(6):930–2.

lymphoblastic leukemia. Leukemia. 2011 Feb;25(2):254–8.

acute lymphoblastic leukemia. Blood. 2008 Nov 15;112(10):4178–83.

41(3):278–83.

2009 Feb;10(2):125–34.

2004 Mar 15;117(Pt 8):1281–3.


[169] Olivero S, Maroc C, Beillard E, Gabert J, Nietfeld W, Chabannon C, et al. Detection of different Ikaros isoforms in human leukaemias using real-time quantitative polymer‐ ase chain reaction. Br. J. Haematol. 2000 Sep;110(4):826–30.

[157] Yang X, Xu B, Sabath I, Kunduru L, Burch BD, Marzluff WF, et al. FLASH is required for the endonucleolytic cleavage of histone pre-mRNAs but is dispensable for the 5' exonucleolytic degradation of the downstream cleavage product. Mol. Cell. Biol.

[158] Flotho C, Coustan-Smith E, Pei D, Iwamoto S, Song G, Cheng C, et al. Genes contri‐ buting to minimal residual disease in childhood acute lymphoblastic leukemia: prog‐

[159] Flotho C, Coustan-Smith E, Pei D, Cheng C, Song G, Pui C-H, et al. A set of genes that regulate cell proliferation predicts treatment outcome in childhood acute lym‐

[160] Jiao Y, Cui L, Gao C, Li W, Zhao X, Liu S, et al. CASP8AP2 is a promising prognostic indicator in pediatric acute lymphoblastic leukemia. Leuk. Res. 2012 Jan;36(1):67–71.

[161] Remke M, Pfister S, Kox C, Toedt G, Becker N, Benner A, et al. High-resolution ge‐ nomic profiling of childhood T-ALL reveals frequent copy-number alterations affect‐ ing the TGF-beta and PI3K-AKT pathways and deletions at 6q15-16.1 as a genomic marker for unfavorable early treatment response. Blood. 2009 Jul 30;114(5):1053–62.

[162] Molnár A, Georgopoulos K. The Ikaros gene encodes a family of functionally diverse zinc finger DNA-binding proteins. Mol. Cell. Biol. 1994 Dec;14(12):8292–303.

[163] Sun L, Liu A, Georgopoulos K. Zinc finger-mediated protein interactions modulate Ikaros activity, a molecular control of lymphocyte development. EMBO J. 1996 Oct

[164] Sun L, Goodman PA, Wood CM, Crotty ML, Sensel M, Sather H, et al. Expression of aberrantly spliced oncogenic ikaros isoforms in childhood acute lymphoblastic leuke‐

[165] Sun L, Heerema N, Crotty L, Wu X, Navara C, Vassilev A, et al. Expression of domi‐ nant-negative and mutant isoforms of the antileukemic transcription factor Ikaros in infant acute lymphoblastic leukemia. Proc. Natl. Acad. Sci. U.S.A. 1999 Jan 19;96(2):

[166] Sun L, Crotty ML, Sensel M, Sather H, Navara C, Nachman J, et al. Expression of dominant-negative Ikaros isoforms in T-cell acute lymphoblastic leukemia. Clin.

[167] Mullighan CG, Su X, Zhang J, Radtke I, Phillips LAA, Miller CB, et al. Deletion of IKZF1 and prognosis in acute lymphoblastic leukemia. N. Engl. J. Med. 2009 Jan

[168] Mullighan CG, Miller CB, Radtke I, Phillips LA, Dalton J, Ma J, et al. BCR-ABL1 lym‐ phoblastic leukaemia is characterized by the deletion of Ikaros. Nature. 2008 May

nostic significance of CASP8AP2. Blood. 2006 Aug 1;108(3):1050–7.

phoblastic leukemia. Blood. 2007 Aug 15;110(4):1271–7.

232 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

2011 Apr;31(7):1492–502.

1;15(19):5358–69.

29;360(5):470–80.

1;453(7191):110–4.

680–5.

mia. J. Clin. Oncol. 1999 Dec;17(12):3753–66.

Cancer Res. 1999 Aug;5(8):2112–20.


[181] Kearney L, Gonzalez De Castro D, Yeung J, Procter J, Horsley SW, Eguchi-Ishimae M, et al. Specific JAK2 mutation (JAK2R683) and multiple gene deletions in Down syndrome acute lymphoblastic leukemia. Blood. 2009 Jan 15;113(3):646–8.

[191] Yoda A, Yoda Y, Chiaretti S, Bar-Natan M, Mani K, Rodig SJ, et al. Functional screen‐ ing identifies CRLF2 in precursor B-cell acute lymphoblastic leukemia. Proc. Natl.

Genetic Markers in the Prognosis of Childhood Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54288

235

[192] Buitenkamp TD, Pieters R, Gallimore NE, van der Veer A, Meijerink JPP, Beverloo HB, et al. Outcome in children with Down's syndrome and acute lymphoblastic leu‐ kemia: role of IKZF1 deletions and CRLF2 aberrations. Leukemia. 2012. Available

from: http://www.ncbi.nlm.nih.gov/pubmed/22441210 ( accessed 22 Mar 2012)

[193] Carpino N, Thierfelder WE, Chang M, Saris C, Turner SJ, Ziegler SF, et al. Absence of an essential role for thymic stromal lymphopoietin receptor in murine B-cell devel‐

Acad. Sci. U.S.A. 2010 Jan 5;107(1):252–7.

opment. Mol. Cell. Biol. 2004 Mar;24(6):2584–92.


[191] Yoda A, Yoda Y, Chiaretti S, Bar-Natan M, Mani K, Rodig SJ, et al. Functional screen‐ ing identifies CRLF2 in precursor B-cell acute lymphoblastic leukemia. Proc. Natl. Acad. Sci. U.S.A. 2010 Jan 5;107(1):252–7.

[181] Kearney L, Gonzalez De Castro D, Yeung J, Procter J, Horsley SW, Eguchi-Ishimae M, et al. Specific JAK2 mutation (JAK2R683) and multiple gene deletions in Down

[182] Mullighan CG, Zhang J, Harvey RC, Collins-Underwood JR, Schulman BA, Phillips LA, et al. JAK mutations in high-risk childhood acute lymphoblastic leukemia. Proc.

[183] Russell LJ, Capasso M, Vater I, Akasaka T, Bernard OA, Calasanz MJ, et al. Deregu‐ lated expression of cytokine receptor gene, CRLF2, is involved in lymphoid transfor‐ mation in B-cell precursor acute lymphoblastic leukemia. Blood. 2009 Sep 24;114(13):

[184] Ziegler SF, Liu Y-J. Thymic stromal lymphopoietin in normal and pathogenic T cell

[185] Akasaka T, Balasas T, Russell LJ, Sugimoto K, Majid A, Walewska R, et al. Five mem‐ bers of the CEBP transcription factor family are targeted by recurrent IGH transloca‐ tions in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Blood. 2007 Apr

[186] Hertzberg L, Vendramini E, Ganmore I, Cazzaniga G, Schmitz M, Chalker J, et al. Down syndrome acute lymphoblastic leukemia, a highly heterogeneous disease in which aberrant expression of CRLF2 is associated with mutated JAK2: a report from

[187] Cario G, Zimmermann M, Romey R, Gesk S, Vater I, Harbott J, et al. Presence of the P2RY8-CRLF2 rearrangement is associated with a poor prognosis in non-high-risk precursor B-cell acute lymphoblastic leukemia in children treated according to the

[188] Harvey RC, Mullighan CG, Chen I-M, Wharton W, Mikhail FM, Carroll AJ, et al. Re‐ arrangement of CRLF2 is associated with mutation of JAK kinases, alteration of IKZF1, Hispanic/Latino ethnicity, and a poor outcome in pediatric B-progenitor acute

[189] Ensor HM, Schwab C, Russell LJ, Richards SM, Morrison H, Masic D, et al. Demo‐ graphic, clinical, and outcome features of children with acute lymphoblastic leuke‐ mia and CRLF2 deregulation: results from the MRC ALL97 clinical trial. Blood. 2011

[190] Palmi C, Vendramini E, Silvestri D, Longinotti G, Frison D, Cario G, et al. Poor prog‐ nosis for P2RY8-CRLF2 fusion but not for CRLF2 over-expression in children with in‐ termediate risk B-cell precursor acute lymphoblastic leukemia. Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K [Inter‐ net]. 2012 Apr 9 [cited 2012 Jul 30]; Available from: http://www.ncbi.nlm.nih.gov/

the International BFM Study Group. Blood. 2010 Feb 4;115(5):1006–17.

ALL-BFM 2000 protocol. Blood. 2010 Jul 1;115(26):5393–7.

lymphoblastic leukemia. Blood. 2010 Jul 1;115(26):5312–21.

development and function. Nat. Immunol. 2006 Jul;7(7):709–14.

syndrome acute lymphoblastic leukemia. Blood. 2009 Jan 15;113(3):646–8.

Natl. Acad. Sci. U.S.A. 2009 Jun 9;106(23):9414–8.

234 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

2688–98.

15;109(8):3451–61.

Feb 17;117(7):2129–36.

pubmed/22484421


**Chapter 10**

**Survival of Patients with**

Berenice Illades-Aguiar and Marco Antonio Leyva-Vázquez

http://dx.doi.org/10.5772/54261

survival of patients with ALL.

**1. Introduction**

**Acute Lymphoblastic Leukemia**

Jorge Organista-Nava, Yazmín Gómez-Gómez,

Additional information is available at the end of the chapter

Over the past 50 years, the treatment of patients with acute lymphoblastic leukemia (ALL) has significantly improved. This success is measured by the improved survival of ALL pa‐ tients from less than 10% in the 1960s to more than 80% in more recent reports. However, many factors influence to a good outcome to treatment and subsequently in the improved

Age is the factor that has been more associated with survival. Younger patients (especial‐ ly those younger than age 50) have a better survival than older patients. Not only age but also gender and race also are related with survival of ALL patients. The girls have showed a better survival than boys, this partly due to boys' risks for testicular cancer. African-American and Hispanic Individuals have lower survival rates than Caucasian and Asian individual, but this may be due to poorer access to treatment. A very impor‐ tant factor in the clinic that somehow predicts good to bad prognosis of the patient and of course has also been linked to survival is the Initial white blood cell (WBC) count; people diagnosed with a WBC count below 50,000/μL tend to be better than people with higher WBC counts. Even, ALL subtype plays a role very important. For example, pa‐ tients with T-cell ALL tend to have a better prognosis and survival than those with ma‐ ture B-cell ALL (Burkitt leukemia). Nowadays, the identification of chromosome translocations help to prognosis of ALL patients; people who have Philadelphia chromo‐ some-positive ALL tend to have a poorer prognosis, although is important to note that

> © 2013 Organista-Nava et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

and reproduction in any medium, provided the original work is properly cited.

new treatments are helping many of these patients achieve remission.

## **Chapter 10**

## **Survival of Patients with Acute Lymphoblastic Leukemia**

Jorge Organista-Nava, Yazmín Gómez-Gómez, Berenice Illades-Aguiar and Marco Antonio Leyva-Vázquez

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/54261

## **1. Introduction**

Over the past 50 years, the treatment of patients with acute lymphoblastic leukemia (ALL) has significantly improved. This success is measured by the improved survival of ALL pa‐ tients from less than 10% in the 1960s to more than 80% in more recent reports. However, many factors influence to a good outcome to treatment and subsequently in the improved survival of patients with ALL.

Age is the factor that has been more associated with survival. Younger patients (especial‐ ly those younger than age 50) have a better survival than older patients. Not only age but also gender and race also are related with survival of ALL patients. The girls have showed a better survival than boys, this partly due to boys' risks for testicular cancer. African-American and Hispanic Individuals have lower survival rates than Caucasian and Asian individual, but this may be due to poorer access to treatment. A very impor‐ tant factor in the clinic that somehow predicts good to bad prognosis of the patient and of course has also been linked to survival is the Initial white blood cell (WBC) count; people diagnosed with a WBC count below 50,000/μL tend to be better than people with higher WBC counts. Even, ALL subtype plays a role very important. For example, pa‐ tients with T-cell ALL tend to have a better prognosis and survival than those with ma‐ ture B-cell ALL (Burkitt leukemia). Nowadays, the identification of chromosome translocations help to prognosis of ALL patients; people who have Philadelphia chromo‐ some-positive ALL tend to have a poorer prognosis, although is important to note that new treatments are helping many of these patients achieve remission.

© 2013 Organista-Nava et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Effectively, all the above factors (age, gender, race, Initial white blood cell (WBC) count, ALL subtype, and chromosome translocations) have an impact on treatment and survival of patients with leukemia. Since several years it is known that single nucleotide polymor‐ phisms (SNPs) are some of the population genetic variations that greatly influence in the re‐ sponse to treatment of patients with ALL. It has been shown to SNPs modify the metabolism of chemical agents used in chemotherapy by affect the normal activity of enzymes involved in drug metabolism. This speaks of a very important role of these SNPs in the adequately outcome and survival of patients with ALL under treatment. This chapter shows how all the above factors play an important role in the survival to ALL and as the survival of patients with ALL varies according to these factors in different populations. The challenge remains to optimize the treatments according to population groups.

In Italian children between 1 and 18 years of age with newly diagnosed of ALL, enrolled in the AIEOP-BFM ALL 2000 study, had a 7-year EFS and survival of 80.4% and 91.8%, respec‐ tively. However when the children were stratified by minimal residual disease (MRD) their overall 7-year estimates for EFS and survival were 80.7% and 92.8%, respectively [11]. In United Kingdom, children aged 1–18 years survival estimates at 5 years were 87% [12]. In Pakistani population aged > 15 years their median survival was 12.7 months and disease-

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

239

Currently, due to intensive chemotherapy regimens, the outcome of adult ALL has im‐ proved markedly. The complete response rates now are more than 80% [14] and the longterm survival rate is 30%–45% [15]. Based on a study by Stephen Hunger and colleagues, 5 year OS rates now above 90% for the first time (83.7% in the period 1990-1994; 90.4% in the most recent period 2000-2005). This study is based on information on 21,626 ALL patients between 0 and 22 years who were enrolled onto the Children's Oncolocy Group (COG) ALL clinical trials from 1990 to 2005. It is clear that survival improved in all subgroups of ALL (1-9 years), except for infants under the age of 1 year. Besides, 5-year OS also remains signif‐ icantly lower (81.6%) for children over the age of 10 years [16]. Childhood ALL reflects one

of the diagnosis for which the most impressive improvements have been realized [1].

long-term survival, but the factor toxicity could have a negative effect on long-term.

Survival disparity by the sex of the patient with leukemia has been observed since the nine‐ teen sixties; however, what remains to be fully grasped are the factors responsible for this persisting survival difference between boys and girls. Girls continue to demonstrate surviv‐ al advantage relative to boys. Studies over the past years have repeatedly shown that after diagnosis of pediatric leukemia, boys present with poorer survival that the girls (Table 2).

In 2012 using a large sample and long-term data could help explain the ongoing variance in leukemia survival comparing boys to girls and found that boys are more likely to die from leukemia (Table 1). The explanation to the observed disparity in survival by sex, since most of the patients who had T-cell type were boys, and survival was poorer among boys in this study [19]. A biological explanation for sex disparity in leukemia survival, it is plausible to suspect XY chromosomal instability as a possible contribution to abnormal cellular prolifer‐ ation, thus resulting in a biologically aggressive leukemia among male patients. Also, it

The better results seen among the childhood population as compared to adults with ALL have been attributed to a number of prognostic factors. It is important to consider a number of important differences between younger and older patients with ALL exist. First, the biolo‐ gy of both, underlying disease and the patients' metabolic changes with age are very differ‐ ent between two cohorts [17]. The second major difference is the difference in therapy related toxicity [18]. The third potential cause for a superior outcome in the younger popula‐ tion is relates to the protocols administered. It is important to consider that the treatment protocols from each institution, the dose adjustments and many others factors can increase

free survival was 6.2 months [13].

**3. Gender**

#### **2. Age**

Survival rates for children with ALL have increased dramatically over the past 4 decades, with 5-year survival rates of >90% in recent trials [1]. Data emerging from the surveillance, epidemiology and end results (SEER) database suggest that patients' age serves as a sig‐ nificant prognostic factor that affects clinical outcomes such as overall survival (OS) [2]. The SEER 9 (Atlanta, Connecticut, Detroit, Hawaii, Iowa, New Mexico, San Francisco-Oakland, Seattle-Puget Sound, Utah) showed that the 5-year survival rates for children younger than age 15 years with ALL improved from 61.0% in 1975-1978 to 88.5% in 1999-2002. Adoles‐ cents 15 to 19 years of age also showed improvement in survival over the same period, al‐ though their outcome in recent periods (50.1% 5-year survival in 1999-2002) was lower than that among children younger than age 15 years [3]. This lower survival rate partially reflects differences in tumor biology between children and older adolescents and likely also reflects differences in the way medical oncologists and pediatric oncologists have historically treat‐ ed ALL arising in this age group [4, 5]. Survival for infants remains poor compared with that for children 1 to 14 years of age, although 5-year survival rates have increased from 22% in 1975-1978 to 62% in 1999-2002 [3].

In 2005, estimates derived SEER program of the National Cancer Institute placed the number of survivors of childhood ALL in the United States at 49 271 (0-19 years of age) being one of the cancer types with the largest number of survivors to 5-years. However, survival decreased with increasing age, with a relatively notable decline in survival be‐ ginning at ages 20 o more years [6]. As in Japanese population of aged 15-60 years where survival at 5 years is 35.0% [7] and Japanese children younger than 16 years age had 7-year OS rate of 76.0% [8]. In work done at Department of Epidemiology and Can‐ cer Control, St Jude Children's Research Hospital, Memphis, TN of 1991 to 2006 in chil‐ dren with acute lymphoblastic leukemia; 5-year event-free survival (EFS) estimates were 88% for children aged 1–9 years, 73% for adolescents aged 10–15 years, 69% for those older than 15 years, and 44% for babies younger than 12 months [9, 10]. Today, the longterm survival has increased from approximately 10% in the early- to mid-1960s to more than 90% at St Jude Children's Research Hospital, Memphis, TN [1].

In Italian children between 1 and 18 years of age with newly diagnosed of ALL, enrolled in the AIEOP-BFM ALL 2000 study, had a 7-year EFS and survival of 80.4% and 91.8%, respec‐ tively. However when the children were stratified by minimal residual disease (MRD) their overall 7-year estimates for EFS and survival were 80.7% and 92.8%, respectively [11]. In United Kingdom, children aged 1–18 years survival estimates at 5 years were 87% [12]. In Pakistani population aged > 15 years their median survival was 12.7 months and diseasefree survival was 6.2 months [13].

Currently, due to intensive chemotherapy regimens, the outcome of adult ALL has im‐ proved markedly. The complete response rates now are more than 80% [14] and the longterm survival rate is 30%–45% [15]. Based on a study by Stephen Hunger and colleagues, 5 year OS rates now above 90% for the first time (83.7% in the period 1990-1994; 90.4% in the most recent period 2000-2005). This study is based on information on 21,626 ALL patients between 0 and 22 years who were enrolled onto the Children's Oncolocy Group (COG) ALL clinical trials from 1990 to 2005. It is clear that survival improved in all subgroups of ALL (1-9 years), except for infants under the age of 1 year. Besides, 5-year OS also remains signif‐ icantly lower (81.6%) for children over the age of 10 years [16]. Childhood ALL reflects one of the diagnosis for which the most impressive improvements have been realized [1].

The better results seen among the childhood population as compared to adults with ALL have been attributed to a number of prognostic factors. It is important to consider a number of important differences between younger and older patients with ALL exist. First, the biolo‐ gy of both, underlying disease and the patients' metabolic changes with age are very differ‐ ent between two cohorts [17]. The second major difference is the difference in therapy related toxicity [18]. The third potential cause for a superior outcome in the younger popula‐ tion is relates to the protocols administered. It is important to consider that the treatment protocols from each institution, the dose adjustments and many others factors can increase long-term survival, but the factor toxicity could have a negative effect on long-term.

## **3. Gender**

Effectively, all the above factors (age, gender, race, Initial white blood cell (WBC) count, ALL subtype, and chromosome translocations) have an impact on treatment and survival of patients with leukemia. Since several years it is known that single nucleotide polymor‐ phisms (SNPs) are some of the population genetic variations that greatly influence in the re‐ sponse to treatment of patients with ALL. It has been shown to SNPs modify the metabolism of chemical agents used in chemotherapy by affect the normal activity of enzymes involved in drug metabolism. This speaks of a very important role of these SNPs in the adequately outcome and survival of patients with ALL under treatment. This chapter shows how all the above factors play an important role in the survival to ALL and as the survival of patients with ALL varies according to these factors in different populations. The challenge remains

Survival rates for children with ALL have increased dramatically over the past 4 decades, with 5-year survival rates of >90% in recent trials [1]. Data emerging from the surveillance, epidemiology and end results (SEER) database suggest that patients' age serves as a sig‐ nificant prognostic factor that affects clinical outcomes such as overall survival (OS) [2]. The SEER 9 (Atlanta, Connecticut, Detroit, Hawaii, Iowa, New Mexico, San Francisco-Oakland, Seattle-Puget Sound, Utah) showed that the 5-year survival rates for children younger than age 15 years with ALL improved from 61.0% in 1975-1978 to 88.5% in 1999-2002. Adoles‐ cents 15 to 19 years of age also showed improvement in survival over the same period, al‐ though their outcome in recent periods (50.1% 5-year survival in 1999-2002) was lower than that among children younger than age 15 years [3]. This lower survival rate partially reflects differences in tumor biology between children and older adolescents and likely also reflects differences in the way medical oncologists and pediatric oncologists have historically treat‐ ed ALL arising in this age group [4, 5]. Survival for infants remains poor compared with that for children 1 to 14 years of age, although 5-year survival rates have increased from 22% in

In 2005, estimates derived SEER program of the National Cancer Institute placed the number of survivors of childhood ALL in the United States at 49 271 (0-19 years of age) being one of the cancer types with the largest number of survivors to 5-years. However, survival decreased with increasing age, with a relatively notable decline in survival be‐ ginning at ages 20 o more years [6]. As in Japanese population of aged 15-60 years where survival at 5 years is 35.0% [7] and Japanese children younger than 16 years age had 7-year OS rate of 76.0% [8]. In work done at Department of Epidemiology and Can‐ cer Control, St Jude Children's Research Hospital, Memphis, TN of 1991 to 2006 in chil‐ dren with acute lymphoblastic leukemia; 5-year event-free survival (EFS) estimates were 88% for children aged 1–9 years, 73% for adolescents aged 10–15 years, 69% for those older than 15 years, and 44% for babies younger than 12 months [9, 10]. Today, the longterm survival has increased from approximately 10% in the early- to mid-1960s to more

than 90% at St Jude Children's Research Hospital, Memphis, TN [1].

to optimize the treatments according to population groups.

238 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

**2. Age**

1975-1978 to 62% in 1999-2002 [3].

Survival disparity by the sex of the patient with leukemia has been observed since the nine‐ teen sixties; however, what remains to be fully grasped are the factors responsible for this persisting survival difference between boys and girls. Girls continue to demonstrate surviv‐ al advantage relative to boys. Studies over the past years have repeatedly shown that after diagnosis of pediatric leukemia, boys present with poorer survival that the girls (Table 2).

In 2012 using a large sample and long-term data could help explain the ongoing variance in leukemia survival comparing boys to girls and found that boys are more likely to die from leukemia (Table 1). The explanation to the observed disparity in survival by sex, since most of the patients who had T-cell type were boys, and survival was poorer among boys in this study [19]. A biological explanation for sex disparity in leukemia survival, it is plausible to suspect XY chromosomal instability as a possible contribution to abnormal cellular prolifer‐ ation, thus resulting in a biologically aggressive leukemia among male patients. Also, it might be possible that testosterone or estrogen may play a small role in pediatric leukemia, this partly due to boys' risks for develop testicular cancer [19].

>50 109

to the WBC [26-28].

**Race/ethnicity**

Non-Hispanic white

Hispanic

Whites

Whites

**5. Race/ethnicity**

racial differences in outcome [33].

**Table 2.** Recent studies on survival of ALL patients by race/ethnicity

ports from various study groups (Table 1).

/L) were significantly related to lower survival. Similar findings are the rule in re‐

The cytogenetic features are closely linked to the WBC and at least partly explain the prognostic of WBC, although there is evidence that children with similar cytogenetic aberrations may have very different WBCs, and their prognostic value is related partly

> **Survival estimated**

At 5 years

Asian/Pasific islander 56 2,542 Non-Hispanic black 46 408

Children At 5 years

Children At 5 years

Blacks 65 506 Hispanics 69 1071 Asians 84 167

Blacks 57 356 Asians 71 410 Native American 54 61 Hispanics 63 504

Variability in survival outcome across racial and ethnic groups (hereafter referred to as race/ ethnicity) also has been identified in some, but not all, clinical research. Survival rates in Black, Hispanic and Native American children with ALL have been somewhat lower than the rates in White children with ALL (Table 2). This difference may be therapy-dependent [32]. Asian children with ALL fare slightly better than white children [33]. The reason for better outcome in White and Asian children compared with Black, Native American and Hispanic children is at least partially explained by the different spectrum of ALL subtypes. For example, blacks have a higher incidence of T-cell ALL and lower rates of favorable ge‐ netic subtypes of ALL. However, these differences do not completely explain the observed

Children

**% of Overall Survival**

**Number of patients**

http://dx.doi.org/10.5772/54261

70 1,529

Survival of Patients With Acute Lymphoblastic Leukemia

56 178

78 6703

70 3621

**Ref.**

241

[29]

[30]

[31]


**Table 1.** Recent studies on survival of ALL patients by gender and Initial white blood cell (WBC) count

#### **4. Initial White Blood Cell (WBC) count**

Along with age, the initial peripheral blood leukocyte count is another of the firsts iden‐ tified prognostic factors in every study of ALL. The WBC at diagnosis is a crucial varia‐ ble for describing the nature of the patient's leukemia and especially the tumor burden. The other measures of the tumor burden are the size of a mediastinal mass, hepatosple‐ nomegaly, and enlargement of lymph nodes. Children with WBC of more than 50x109 /L are commonly considered to be at high risk of relapse and receive intensive treatment [1, 2]. In retrospective analysis was found that patients with hyperleukocytosis (WBC count >50 109 /L) were significantly related to lower survival. Similar findings are the rule in re‐ ports from various study groups (Table 1).

The cytogenetic features are closely linked to the WBC and at least partly explain the prognostic of WBC, although there is evidence that children with similar cytogenetic aberrations may have very different WBCs, and their prognostic value is related partly to the WBC [26-28].


**Table 2.** Recent studies on survival of ALL patients by race/ethnicity

## **5. Race/ethnicity**

might be possible that testosterone or estrogen may play a small role in pediatric leukemia,

*Sex*

**WBC count**

Children At 5 years

Children At 5 years

Children At 5 years

Children At 7 years

Adults At 5 years

3x109-50x109/L 48.8 45 >50x109/L 19.2 27

≥100.0x10<sup>3</sup>/μL 57.1 17

50.0-99.9x109/L 77.6 1,647 ≥100.0x109/L 50.1 189

>50x109/L 61.0 166 U.S. <50,000/µL Children At 4 years 80.3 68 [25]

Children At 5 years

Children At 5 years

Along with age, the initial peripheral blood leukocyte count is another of the firsts iden‐ tified prognostic factors in every study of ALL. The WBC at diagnosis is a crucial varia‐ ble for describing the nature of the patient's leukemia and especially the tumor burden. The other measures of the tumor burden are the size of a mediastinal mass, hepatosple‐ nomegaly, and enlargement of lymph nodes. Children with WBC of more than 50x109

are commonly considered to be at high risk of relapse and receive intensive treatment [1, 2]. In retrospective analysis was found that patients with hyperleukocytosis (WBC count

**Table 1.** Recent studies on survival of ALL patients by gender and Initial white blood cell (WBC) count

10.0-49.9x109/L 62.7 206 50.0-99.9x109/L 52.9 35 ≥100.0x109/L 19.3 48

**Survival estimated**

53.9 8,622 [19] Female 58.0 6,593

[20] Female 67.0 <sup>299</sup>

63.5 1,151 [21] Female 73.4 <sup>904</sup>

**% of Overall Survival**

**Number of patients**

71.5 300 [22]

20.0 15 [23]

87.5 83 [24]

92.3 1,348 [11]

94.0 923 [12]

/L

63.0 401

**Ref.**

this partly due to boys' risks for develop testicular cancer [19].

240 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Korean <100.0x103/μL Children At 4 years

**Population**

Male

Male

Male

Japanese < 10.0x109/L

Japanese <3x109/L

European <50x109/L

European <50x109/L

**4. Initial White Blood Cell (WBC) count**

U.S.

European

U.S.

Variability in survival outcome across racial and ethnic groups (hereafter referred to as race/ ethnicity) also has been identified in some, but not all, clinical research. Survival rates in Black, Hispanic and Native American children with ALL have been somewhat lower than the rates in White children with ALL (Table 2). This difference may be therapy-dependent [32]. Asian children with ALL fare slightly better than white children [33]. The reason for better outcome in White and Asian children compared with Black, Native American and Hispanic children is at least partially explained by the different spectrum of ALL subtypes. For example, blacks have a higher incidence of T-cell ALL and lower rates of favorable ge‐ netic subtypes of ALL. However, these differences do not completely explain the observed racial differences in outcome [33].


Notably, children and young adults 1 to 4 and 5 to 19 years of age with B-cell ALL had more favorable survival (Approximately 99% and 88%) than those with T-cell ALL (Approximate‐ ly 84% and 78%). In contrast, survival for T-cell ALL was substantially higher than B-cell

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

243

**7.** *Chromosomal translocations in* **B-cell acute lymphoblastic leukemia**

Acute lymphoblastic leukemia is a heterogeneous disease that originates from lymphocyte progenitor cells of B- or T-cell origin. ALL comprises multiple distinct subtypes that are characterized by recurrent copy number alterations and structural chromosomal rearrange‐ ments, which have important clinical implications. Such cytogenetically distinct subtypes in‐ clude B-cell precursor (BCP) leukemia with the chromosomal translocations t(12;21) (p13;q22) [ETV6/RUNX1], t(9;22)(q11;q34) [BCR/ABL1], (4;11)(q21;q23)/MLL-AF4, *t(11;19)/ MLL-ENL, t(1;19)(q23;p13)/PBX1/E2A* karyotypes. It is well established that ALL subtypes differ from a clinical perspective, but the underlying molecular consequences of most of the

**8. ETV6-RUNX1 [t(12;21) cryptic translocation, formerly known as TEL-**

The translocation t(12;21)(p13;q22) is the most frequent chromosomal alteration in childhood Blineage ALL (B-ALL) [54], which involves the fusion of the ETV6 (alias TEL) gene on chromo‐ some 12 to the RUNX1 gene on chromosome 21. It is identified in 20% to 25% of the cases of Bprecursor ALL and is rarely observed in T-lineage ALL [55]. The t(12;21) is most commonly found in children aged 2 to 9 years [56]. Reports generally indicate favorable OS in children with the ETV6-RUNX1 fusion (Table 3); however, the prognostic impact of this genetic feature is

The Ph results from a reciprocal translocation (t) between chromosomes 9 and 22 (t [9,22] [q34;q11]) [58, 59], occurs in approximately 3 to 5% of children, as compared with up to 30

The Ph produces a fusion gene on chromosome 22, namely, the breakpoint cluster region Abelson leukemia viral proto-oncogene (BCR-ABL). The translocation can result in 3 fusion protein of different sizes: p190, p210, and p230 [62]. The p190 BCR-ABL fusion gene occurs in about 90% of children with Ph-positive ALL [63] and between 50% and 80% of adults

modified by factors such as early response to treatment and treatment regimen [57].

**9. Philadelphia chromosome (Ph) or t(9;22) translocation**

percent of adults with ALL [60, 61].

with Ph-positive ALL [64, 65].

ALL among adults 20 to 39, 40 to 59, and 60 years or older of age [52].

recurrent chromosomal abnormalities are poorly understood [53].

**(B-cell ALL)**

**AML1]**

**Table 3.** Studies on survival of ALL patients with genetic rearrangements

#### **6. Survival by ALL Immunophenotype**

The World Health Organization (WHO) classifies ALL as either B lymphoblastic leukemia or T lymphoblastic leukemia [49]. Historically, T-cell ALL patients have had a worse prog‐ nosis than other ALL, the relapse rate of T-cell ALL is greater than B-cell ALL cases, and Tcell ALL cases have shown less EFS than B-ALL cases [50, 51]. Patients with T-cell ALL treated on Dana-Farber Cancer Institute (DFCI) Boston, MA had an overall survival at 5 years of 78 % compared with 86 % for B progenitor ALL patients [50]. A study based cancer registry areas of the Surveillance, Epidemiology and End Results (SEER) Program (SEER-17) during 2001 to 2007 reported that infants with B-cell ALL and ALL of unknown lineage had intermediate survival to 5-years compared with 5- to 19-year and 20- to 39-year age groups. Notably, children and young adults 1 to 4 and 5 to 19 years of age with B-cell ALL had more favorable survival (Approximately 99% and 88%) than those with T-cell ALL (Approximate‐ ly 84% and 78%). In contrast, survival for T-cell ALL was substantially higher than B-cell ALL among adults 20 to 39, 40 to 59, and 60 years or older of age [52].

**Population**

Spanish Infants, Children,

**Table 3.** Studies on survival of ALL patients with genetic rearrangements

**6. Survival by ALL Immunophenotype**

**Survival estimated**

242 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

*ETV6-RUNX1 [t(12;21)]*

*BCR-ABL [t(9;22)]*

*MLL-AF4[t(4;11) (q21;q23)]*

*PBX1/E2A[ t(1;19)(q23;p13.3)/der(19)t(1;19)(q23;p13.3)]*

The World Health Organization (WHO) classifies ALL as either B lymphoblastic leukemia or T lymphoblastic leukemia [49]. Historically, T-cell ALL patients have had a worse prog‐ nosis than other ALL, the relapse rate of T-cell ALL is greater than B-cell ALL cases, and Tcell ALL cases have shown less EFS than B-ALL cases [50, 51]. Patients with T-cell ALL treated on Dana-Farber Cancer Institute (DFCI) Boston, MA had an overall survival at 5 years of 78 % compared with 86 % for B progenitor ALL patients [50]. A study based cancer registry areas of the Surveillance, Epidemiology and End Results (SEER) Program (SEER-17) during 2001 to 2007 reported that infants with B-cell ALL and ALL of unknown lineage had intermediate survival to 5-years compared with 5- to 19-year and 20- to 39-year age groups.

Caucasian Children At 5 years 90.0 31 [46] U.S. Children At 5 years 84.2 41 [47] Europe Children At 5 years 84.0 50 [12] Europe Adults At 5 years 79.0 47 [48]

Brazilian Children At 5 years 77.6 58 [34] Nordic countries Children At 5 years 65.0 669 [35] U.S. Children At 5 years 93.7 662 [36] French Children At 5 years 50.0 73 [37]

Spanish Adults At 4 years 16.0 30 [38] Europe and U.S. Children At 2 years 35.5 - 46.3 267 [39] U.S. Children At 4 years 35.0 120 [40] Japanese Adults At 2 years 12.5 80 [41]

Europe Adults At 5 years 39.0 236 [42] Japanese Infants At 3 years 43.5 54 [43] Europe Adults At 5 years 13.0 24 [44]

Adults At 5 years 36.0 <sup>51</sup> [45]

**% of Overall Survival**

**Number of patients**

**Ref.**

## **7.** *Chromosomal translocations in* **B-cell acute lymphoblastic leukemia (B-cell ALL)**

Acute lymphoblastic leukemia is a heterogeneous disease that originates from lymphocyte progenitor cells of B- or T-cell origin. ALL comprises multiple distinct subtypes that are characterized by recurrent copy number alterations and structural chromosomal rearrange‐ ments, which have important clinical implications. Such cytogenetically distinct subtypes in‐ clude B-cell precursor (BCP) leukemia with the chromosomal translocations t(12;21) (p13;q22) [ETV6/RUNX1], t(9;22)(q11;q34) [BCR/ABL1], (4;11)(q21;q23)/MLL-AF4, *t(11;19)/ MLL-ENL, t(1;19)(q23;p13)/PBX1/E2A* karyotypes. It is well established that ALL subtypes differ from a clinical perspective, but the underlying molecular consequences of most of the recurrent chromosomal abnormalities are poorly understood [53].

## **8. ETV6-RUNX1 [t(12;21) cryptic translocation, formerly known as TEL-AML1]**

The translocation t(12;21)(p13;q22) is the most frequent chromosomal alteration in childhood Blineage ALL (B-ALL) [54], which involves the fusion of the ETV6 (alias TEL) gene on chromo‐ some 12 to the RUNX1 gene on chromosome 21. It is identified in 20% to 25% of the cases of Bprecursor ALL and is rarely observed in T-lineage ALL [55]. The t(12;21) is most commonly found in children aged 2 to 9 years [56]. Reports generally indicate favorable OS in children with the ETV6-RUNX1 fusion (Table 3); however, the prognostic impact of this genetic feature is modified by factors such as early response to treatment and treatment regimen [57].

## **9. Philadelphia chromosome (Ph) or t(9;22) translocation**

The Ph results from a reciprocal translocation (t) between chromosomes 9 and 22 (t [9,22] [q34;q11]) [58, 59], occurs in approximately 3 to 5% of children, as compared with up to 30 percent of adults with ALL [60, 61].

The Ph produces a fusion gene on chromosome 22, namely, the breakpoint cluster region Abelson leukemia viral proto-oncogene (BCR-ABL). The translocation can result in 3 fusion protein of different sizes: p190, p210, and p230 [62]. The p190 BCR-ABL fusion gene occurs in about 90% of children with Ph-positive ALL [63] and between 50% and 80% of adults with Ph-positive ALL [64, 65].

Ph-positive ALL has an extremely poor prognosis overall (rates of EFS are 30 to 46 percent in children and less than 20 percent in adults) Table 3. However, some investigators suggest that in this type of ALL, the prognosis is influenced by the treatment with glucocorticoids (and intrathecal methotrexate) [66], or by other factors (such as age and leukocyte count at diagnosis) [67, 68]. These variations in the response to therapy suggest that Ph-positive ALL is heterogeneous with regard to sensitivity to treatment [39].

cations have been identified in T-cell ALL, with many genes encoding for transcription factors (e.g., TAL1; [t(1;14)(p32;q11) and t(1;7)(p32;q34)], LMO1; [t(11;14)(p15;q11)], LMO2; [t(11;14)(p13;q11) and t(7;11)(q35;p13)], LYL1; [t(7;19)(q34;p13)], TLX1/HOX11 [t(7;10) (q34;q24) and t(10;14)(q24;q11)], and TLX3/HOX11L2 [t(5;14)(q35;q32)]) fusing to one of the T-cell receptor (TCR) loci and resulting in aberrant expression of these transcription factors in leukemia cells [81]. Historically, T-cell ALL in children has been associated with a worse

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

245

High expression of TLX1/HOX11 resulting from translocations involving this gene occurs in 5% to 10% of pediatric T-cell ALL cases and is associated with more favorable outcome in both adults and children with T-cell ALL [84-86]. Overexpression of TLX3/HOX11L2 result‐ ing from the t(5;14)(q35;q32) translocation occurs in approximately 20% of pediatric T-cell

ALL cases and appears to be associated with increased risk of treatment failure [85].

**12. Gene polymorphisms associated to poor survival in ALL patients**

It is difficult to define which component of the protocol/regimen is the responsible for the improved outcome of patients with ALL. Antifolates, such as methotrexate (MTX), are com‐ petitive inhibitors of folate-dependent enzymes and are widely used in the treatment of many human cancers [87]. In last decades, the MTX has been a key agent for the treatment of ALL and the benefit of high-dose MTX is well established as it significantly increases cure rates and improves patients' prognosis [88]. MTX exerts its cytotoxic effects by competitive‐ ly inhibiting dihydrofolate reductase (DHFR), the enzyme responsible for converting folates to tetrahydrofolate, the reduced folate carriers which function in the transfer of carbon units. These carbon units are required for de novo purine synthesis and the methylation of uracil

MTX enters the cells and is metabolized into 7-hydroxymethotrexate (7-OHMTX), 2,4-diami‐ no-N10-methylpteroic acid (DAMPA) and more active derivatives as methotrexate polyglu‐ tamates (MTXPG) with sequential gamma-linkage of 2 to 6 glutamyl residues by the folylpolyglutamate synthetase (FPGS) [88]. MTXPG retained in cells for a longer time result in prolonged MTX antifolate effect [89]. However, accumulation of MTXPG is a critical fac‐ tor associated with cytotoxicity and response of ALL patients to the therapy [89]. On the oth‐ er hand, the polyglutamation process competes with deconjugation that converts MTXPG back into MTX by gamma-glutamyl hydrolase (GGH). Long chain MTXPG have higher af‐ finity than MTX for the enzymes involved in de novo purine synthesis such as 5-aminoimi‐ dazole-4-carboxamide ribonucleotide transformylase (ATIC) and thymidilate synthase (TS), which results in a reinforcement of MTX inhibition (Figure 1) [88]. Thus, intracellular forma‐

The disease-free survival of childhood ALL has improved steadily the last decades, reaching 80% in the developed countries [17]. Despite the advances, almost 20% of the children either relapse or do not respond to treatment. This seems to be related to various parameters, in‐

tion of MTXPG enhances the cytotoxic and antileukemic effect of MTX.

prognosis than other sub-types of childhood ALL [82, 83].

to thymine in DNA synthesis [89].

## **10. MLL translocations**

#### **10.1. MLL-AF4; t(4;11) (q21;q23) translocation**

The incidence of t(4;11)(q21;q23)/MLL-AF4, occurring in over 50% ALL cases in infants aged less than 6 months, in 10–20% of older infants, in about 2% of children, and in almost 10% of adults [69, 70]. The presence of the translocation t(4;11)(q21;q23) or a fusion gene MLL-AF4 is detected in almost 10% of newly diagnosed B-cell ALL and in about 30–40% of pro-B ALL subtypes [71, 72].

A t(4;11)(q21;q23)/MLL-AF4 positive ALL is generally considered as a high risk leukemia, char‐ acterized by a poor clinical outcome respect to other cytogenetic risk groups [73]. Moreover, in several studies it has been demonstrated that cytogenetic-molecular risk and WBC count at di‐ agnosis were the main prognostic factors that influenced OS in ALL patients (Table 3).

#### **10.2. MLL-ENL; t(11;19) translocation**

*The t(11;19)/ MLL-ENL* is present in approximately 1% of cases and occurs in both early Bcell and T-cell ALL [74]. Outcome for infants with t(11;19) is poor, but outcome appears rela‐ tively favorable in older children with T-cell ALL and the t(11;19) translocation [74].

#### **10.3. PBX1/E2A; t(1;19)(q23;p13) translocation**

The translocation t(1;19)(q23;p13), and its unbalanced variant del(19)t(1;19)(q23;p13), is a primary and well known chromosome abnormality in childhood B-cell precursor ALL, be‐ ing present in 3–5% of all such cases [75, 76].

The t(1;19) produces a fusion between TCF3 gene on 19p13 and PBX1 on 1q23 [77], with the TCF3-PBX1 fusion transcript being expressed from the chromosome 19 [78]. Initially, t(1;19) was associated with a poor prognosis in ALL [79, 80], however most patients treated by con‐ temporary therapies now achieve improved outcomes (Table 6).

## **11.** *Chromosomal translocations in* **T-cell acute lymphoblastic leukemia (T-cell ALL)**

T-cell ALL accounts for about 15% and 25% of ALL in pediatric and adult cohorts respec‐ tively [69]. Cytogenetic abnormalities are rare in T-cell ALL. Multiple chromosomal translo‐ cations have been identified in T-cell ALL, with many genes encoding for transcription factors (e.g., TAL1; [t(1;14)(p32;q11) and t(1;7)(p32;q34)], LMO1; [t(11;14)(p15;q11)], LMO2; [t(11;14)(p13;q11) and t(7;11)(q35;p13)], LYL1; [t(7;19)(q34;p13)], TLX1/HOX11 [t(7;10) (q34;q24) and t(10;14)(q24;q11)], and TLX3/HOX11L2 [t(5;14)(q35;q32)]) fusing to one of the T-cell receptor (TCR) loci and resulting in aberrant expression of these transcription factors in leukemia cells [81]. Historically, T-cell ALL in children has been associated with a worse prognosis than other sub-types of childhood ALL [82, 83].

Ph-positive ALL has an extremely poor prognosis overall (rates of EFS are 30 to 46 percent in children and less than 20 percent in adults) Table 3. However, some investigators suggest that in this type of ALL, the prognosis is influenced by the treatment with glucocorticoids (and intrathecal methotrexate) [66], or by other factors (such as age and leukocyte count at diagnosis) [67, 68]. These variations in the response to therapy suggest that Ph-positive ALL

The incidence of t(4;11)(q21;q23)/MLL-AF4, occurring in over 50% ALL cases in infants aged less than 6 months, in 10–20% of older infants, in about 2% of children, and in almost 10% of adults [69, 70]. The presence of the translocation t(4;11)(q21;q23) or a fusion gene MLL-AF4 is detected in almost 10% of newly diagnosed B-cell ALL and in about 30–40% of pro-B ALL

A t(4;11)(q21;q23)/MLL-AF4 positive ALL is generally considered as a high risk leukemia, char‐ acterized by a poor clinical outcome respect to other cytogenetic risk groups [73]. Moreover, in several studies it has been demonstrated that cytogenetic-molecular risk and WBC count at di‐

*The t(11;19)/ MLL-ENL* is present in approximately 1% of cases and occurs in both early Bcell and T-cell ALL [74]. Outcome for infants with t(11;19) is poor, but outcome appears rela‐

The translocation t(1;19)(q23;p13), and its unbalanced variant del(19)t(1;19)(q23;p13), is a primary and well known chromosome abnormality in childhood B-cell precursor ALL, be‐

The t(1;19) produces a fusion between TCF3 gene on 19p13 and PBX1 on 1q23 [77], with the TCF3-PBX1 fusion transcript being expressed from the chromosome 19 [78]. Initially, t(1;19) was associated with a poor prognosis in ALL [79, 80], however most patients treated by con‐

**11.** *Chromosomal translocations in* **T-cell acute lymphoblastic leukemia**

T-cell ALL accounts for about 15% and 25% of ALL in pediatric and adult cohorts respec‐ tively [69]. Cytogenetic abnormalities are rare in T-cell ALL. Multiple chromosomal translo‐

agnosis were the main prognostic factors that influenced OS in ALL patients (Table 3).

tively favorable in older children with T-cell ALL and the t(11;19) translocation [74].

is heterogeneous with regard to sensitivity to treatment [39].

244 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

**10. MLL translocations**

subtypes [71, 72].

**(T-cell ALL)**

**10.1. MLL-AF4; t(4;11) (q21;q23) translocation**

**10.2. MLL-ENL; t(11;19) translocation**

**10.3. PBX1/E2A; t(1;19)(q23;p13) translocation**

ing present in 3–5% of all such cases [75, 76].

temporary therapies now achieve improved outcomes (Table 6).

High expression of TLX1/HOX11 resulting from translocations involving this gene occurs in 5% to 10% of pediatric T-cell ALL cases and is associated with more favorable outcome in both adults and children with T-cell ALL [84-86]. Overexpression of TLX3/HOX11L2 result‐ ing from the t(5;14)(q35;q32) translocation occurs in approximately 20% of pediatric T-cell ALL cases and appears to be associated with increased risk of treatment failure [85].

## **12. Gene polymorphisms associated to poor survival in ALL patients**

It is difficult to define which component of the protocol/regimen is the responsible for the improved outcome of patients with ALL. Antifolates, such as methotrexate (MTX), are com‐ petitive inhibitors of folate-dependent enzymes and are widely used in the treatment of many human cancers [87]. In last decades, the MTX has been a key agent for the treatment of ALL and the benefit of high-dose MTX is well established as it significantly increases cure rates and improves patients' prognosis [88]. MTX exerts its cytotoxic effects by competitive‐ ly inhibiting dihydrofolate reductase (DHFR), the enzyme responsible for converting folates to tetrahydrofolate, the reduced folate carriers which function in the transfer of carbon units. These carbon units are required for de novo purine synthesis and the methylation of uracil to thymine in DNA synthesis [89].

MTX enters the cells and is metabolized into 7-hydroxymethotrexate (7-OHMTX), 2,4-diami‐ no-N10-methylpteroic acid (DAMPA) and more active derivatives as methotrexate polyglu‐ tamates (MTXPG) with sequential gamma-linkage of 2 to 6 glutamyl residues by the folylpolyglutamate synthetase (FPGS) [88]. MTXPG retained in cells for a longer time result in prolonged MTX antifolate effect [89]. However, accumulation of MTXPG is a critical fac‐ tor associated with cytotoxicity and response of ALL patients to the therapy [89]. On the oth‐ er hand, the polyglutamation process competes with deconjugation that converts MTXPG back into MTX by gamma-glutamyl hydrolase (GGH). Long chain MTXPG have higher af‐ finity than MTX for the enzymes involved in de novo purine synthesis such as 5-aminoimi‐ dazole-4-carboxamide ribonucleotide transformylase (ATIC) and thymidilate synthase (TS), which results in a reinforcement of MTX inhibition (Figure 1) [88]. Thus, intracellular forma‐ tion of MTXPG enhances the cytotoxic and antileukemic effect of MTX.

The disease-free survival of childhood ALL has improved steadily the last decades, reaching 80% in the developed countries [17]. Despite the advances, almost 20% of the children either relapse or do not respond to treatment. This seems to be related to various parameters, in‐ cluding the presence of polymorphisms of drug transporters, receptors, targets, and drugmetabolizing enzymes, hence influencing the efficacy, the toxicity of therapy [91].

**13. The reduced folate carrier (RFC1/SLC19A1)**

the rates in European and French-Canadian population (Table 4).

ultimately MTX, allowing folate to be exported from the cell [94].

**14. Folypolyglutamate Hydrolase (GGH)**

matoid arthritis patients treated with MTX [98].

mulation of MTXPG and to MTX resistance [101]

chain MTX in these cells [97].

Several polymorphisms in enzymes of the folate cycle as well as in the MTX transporters have been described. The reduced folate carrier gene (RFC1) is a major MTX transporter whose impaired function was recognized as a frequent mechanism of antifolate resistance [92]. The most common SNP in RFC1, 80A>G, which results in the amino acid substitution of Arg with His at position 27 of the RFC1 protein, may alter the affinity of the transporter [93]. Several investigators had studied the association of the SNP of RFC G80A and the out‐ come in ALL. Reports generally indicate association between the G/G and/or A/G genotypes of the G80A polymorphism with a poorer survival in patient's children and adults con ALL. Survival rates in Italian and Mexican population with ALL have been somewhat lower than

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

247

GGH is a lysosomal peptidase that catalyses the removal of gamma-linked polyglutamates and convert long-chain polyglutamates (n=4–7) into short-chain polyglutamates (n=2–3) and

Several SNPs have been identified in the GGH gene at bases −401C>T, −354G>T, −124T>G, +16T>C, +452C>T, and +1102A>G; these sites comprise both the promoter and the coding region [95, 96]. Nevertheless, few SNPs have been associated with catalytic activity of the GGH in B- and T-lineage ALL cells, and greater accumulation of long-

The polymorphism +452C>T in the transcribed region of GGH gene alters Thr-127 to Ile-1271, and has been associated with reduced catalytic activity in hyperdiploid B- and T-lineage acute lymphocytic leukemia (ALL) cells, and greater accumulation of longchain MTXPG in these cells [97]. In contrast, all of the promoter polymorphisms en‐ hanced GGH expression and an increased GGH activity may lead to decreased accumulation of MTXPG and to MTX resistance. At least one of these, −401C>T, has been shown to be correlated with decreased accumulation of long-chain MTX-Glu3–5 in rheu‐

Only polymorphism -354G>T has been associated with survival of children with ALL. -354GT or -354TT genotypes carrier have better probability of 5-year post-treatment OS compared to -354GG genotypes (*p* = 0.04) (Table 4) [99]. This shows the enzyme GGH clearly plays an important role in the metabolism of folates and anti-folates. However, unambiguous demonstration of a direct role of GGH in anti-folate drug resistance has been difficult. Part of the difficulty is that GGH is only one of several factors that can af‐ fect anti-folate levels, and its role presumably is directly linked to those of the other en‐ zymes. [100]. However, these studies have demonstrated that polymorphisms in GGH increase promoter activity and an increased GGH activity may lead to decreased accu‐

**Figure 1.** Methotrexate enters cells through the reduced **folate carrier** (RFC1) or other transport systems. Its main in‐ tracellular target is **dihydrofolate reductase** (DHFR), inhibition of which results in accumulation of dihydrofolate (DHF) and depletion of cellular folates. Cytosolic **folylpolyglutamyl synthase** (FPGS) adds glutamate residues to me‐ thotrexate to produce methotrexate polyglutamates (MTXPGs), they are retained by the cell, and the resulting in‐ crease the efficacy of methotrexate. The addition of glutamate residues to methotrexate also increases its affinity for other target enzymes (**thymidylate synthetase** (TS) and **dihydrofolate reductase** (DHFR). Other enzymes that are indirectly affected by methotrexate are **5,10-methylenetetrahydrofolate reductase** (MTHFR) and **methylenetetra‐ hydrofolate dehydrogenase** (MTHFD1). dTMP, deoxythymidine monophospate; dUMP, deoxyuridine monopho‐ spate; THF, tetrahydrofolate. Figure modified with permission from Ref. [90] © PharmGKB and Stanford University (2011).

Recently, attention has been drawn on genes involved in diverse metabolic pathways, which are known to be polymorphic at various sites and can affect both the susceptibility for leuke‐ mia, the treatment outcome and survival in patients with ALL [91].

## **13. The reduced folate carrier (RFC1/SLC19A1)**

cluding the presence of polymorphisms of drug transporters, receptors, targets, and drug-

**Figure 1.** Methotrexate enters cells through the reduced **folate carrier** (RFC1) or other transport systems. Its main in‐ tracellular target is **dihydrofolate reductase** (DHFR), inhibition of which results in accumulation of dihydrofolate (DHF) and depletion of cellular folates. Cytosolic **folylpolyglutamyl synthase** (FPGS) adds glutamate residues to me‐ thotrexate to produce methotrexate polyglutamates (MTXPGs), they are retained by the cell, and the resulting in‐ crease the efficacy of methotrexate. The addition of glutamate residues to methotrexate also increases its affinity for other target enzymes (**thymidylate synthetase** (TS) and **dihydrofolate reductase** (DHFR). Other enzymes that are indirectly affected by methotrexate are **5,10-methylenetetrahydrofolate reductase** (MTHFR) and **methylenetetra‐ hydrofolate dehydrogenase** (MTHFD1). dTMP, deoxythymidine monophospate; dUMP, deoxyuridine monopho‐ spate; THF, tetrahydrofolate. Figure modified with permission from Ref. [90] © PharmGKB and Stanford University

Recently, attention has been drawn on genes involved in diverse metabolic pathways, which are known to be polymorphic at various sites and can affect both the susceptibility for leuke‐

mia, the treatment outcome and survival in patients with ALL [91].

(2011).

metabolizing enzymes, hence influencing the efficacy, the toxicity of therapy [91].

246 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Several polymorphisms in enzymes of the folate cycle as well as in the MTX transporters have been described. The reduced folate carrier gene (RFC1) is a major MTX transporter whose impaired function was recognized as a frequent mechanism of antifolate resistance [92]. The most common SNP in RFC1, 80A>G, which results in the amino acid substitution of Arg with His at position 27 of the RFC1 protein, may alter the affinity of the transporter [93]. Several investigators had studied the association of the SNP of RFC G80A and the out‐ come in ALL. Reports generally indicate association between the G/G and/or A/G genotypes of the G80A polymorphism with a poorer survival in patient's children and adults con ALL. Survival rates in Italian and Mexican population with ALL have been somewhat lower than the rates in European and French-Canadian population (Table 4).

## **14. Folypolyglutamate Hydrolase (GGH)**

GGH is a lysosomal peptidase that catalyses the removal of gamma-linked polyglutamates and convert long-chain polyglutamates (n=4–7) into short-chain polyglutamates (n=2–3) and ultimately MTX, allowing folate to be exported from the cell [94].

Several SNPs have been identified in the GGH gene at bases −401C>T, −354G>T, −124T>G, +16T>C, +452C>T, and +1102A>G; these sites comprise both the promoter and the coding region [95, 96]. Nevertheless, few SNPs have been associated with catalytic activity of the GGH in B- and T-lineage ALL cells, and greater accumulation of longchain MTX in these cells [97].

The polymorphism +452C>T in the transcribed region of GGH gene alters Thr-127 to Ile-1271, and has been associated with reduced catalytic activity in hyperdiploid B- and T-lineage acute lymphocytic leukemia (ALL) cells, and greater accumulation of longchain MTXPG in these cells [97]. In contrast, all of the promoter polymorphisms en‐ hanced GGH expression and an increased GGH activity may lead to decreased accumulation of MTXPG and to MTX resistance. At least one of these, −401C>T, has been shown to be correlated with decreased accumulation of long-chain MTX-Glu3–5 in rheu‐ matoid arthritis patients treated with MTX [98].

Only polymorphism -354G>T has been associated with survival of children with ALL. -354GT or -354TT genotypes carrier have better probability of 5-year post-treatment OS compared to -354GG genotypes (*p* = 0.04) (Table 4) [99]. This shows the enzyme GGH clearly plays an important role in the metabolism of folates and anti-folates. However, unambiguous demonstration of a direct role of GGH in anti-folate drug resistance has been difficult. Part of the difficulty is that GGH is only one of several factors that can af‐ fect anti-folate levels, and its role presumably is directly linked to those of the other en‐ zymes. [100]. However, these studies have demonstrated that polymorphisms in GGH increase promoter activity and an increased GGH activity may lead to decreased accu‐ mulation of MTXPG and to MTX resistance [101]


**15. Dihydrofolate Reductase (DHFR)**

reduced survival in pediatric patients with ALL (Table 4).

**16. Thymidylate Synthase (TS)**

*vitro* studies [118, 119].

DHFR is responsible to catalyze the reduction of dihydrofolate (DHF) to tetrahydrofolate (THF) [113]. The major mechanism of MTX action involves competitive inhibition of DHFR, leading to the impaired regeneration of THF from DHF; essential for the biosynthesis of pu‐

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

249

Changes in the levels of DHFR expression and consequently in the sensitivity to MTX can also be due to single SNPs, particularly those located in the regulatory elements [105]. The C829T SNP is located at the 223 nucleotide downstream from the stop codon between the first and second polyadenylation sites in the 3'UTR of the DHFR gene, which leads to the stability of mRNA [116]. A previous study reported that the -A317G SNP in the DHFR pro‐ moter region results in higher transcriptional activity [106]. Recently demonstrated an asso‐ ciation between G/G and T/T genotypes of the -A317G and C829T polymorphisms and

The TS is a key enzyme in the nucleotide biosynthesis and important target of several che‐ motherapeutics. TS provides the only source for de novo thymidylate production by catalyz‐ ing the methylation of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate (dTMP) [107]. TS is efficiently inhibited by the uracil analog, 5-fluorouracil

The most common polymorphism in TS is a unique double (2R) or triple (3R) 28-bp tandem repeat sequence in the 5' untranslated region (5'-UTR) of the TS gene also called TS enhancer region (TSER), immediately upstream from the initiation site, which influences protein ex‐ pression in cancer cells [117]. The presence of a triple versus double 28-bp repeat in the en‐ hancer region has been associated with an increased TS expression both in *in vivo* and *in*

Previous studies have shown that pediatric patients who were homozygous for the triple re‐ peat (3R/3R) had a poorer prognostic (odds ratio 4.1, 95% CI 1 9–9 0, p=0 001) [108] and

The MTHFR is a key folate enzyme that catalyzes the conversion of 5,10-methylenetetrahy‐ drofolate to 5-methyltetrahydrofolate in the folic acid cycle, and is interrupted by metho‐

Despite the fact that several MTHFR polymorphisms have been described thus far, only two polymorphisms, C677T and A1298C, have been intensively investigated. The C-to-T transi‐

(5-FU) and MTX, used for many years as a treatment for a variety of cancers.

shorter survival than those patients with other genotypes (Table 4).

**17. Methylenetetrahydrofolate Reductase (MTHFR)**

trexate (MTX), a critical chemotherapy agent in ALL therapy [120].

rines and thymidylate, thus it also blocks the novo synthesis of DNA [114, 115].

**Table 4.** Genetic polymorphism and its relationship to survival in ALL

## **15. Dihydrofolate Reductase (DHFR)**

**Genotypes Population**

G/G French-Canadian origin

G/G

G/G

G/G

GG

A/A

A/A

C/C

2R/2R or 2R/3R

C

C

C

**Survival estimated**

**80A>G polymorphism in RFC1 gene**

Italian (adults) At 5 years

248 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

Mexican (children) At 5 years

European (children) At 5 years

European (children) At 5 years

Mexican (children) At 5 years

Canadian (children) At 5 years

Mexican (children) At 5 years

French-Canadian (children) At 5 years

Italian (Adults) At 2 years

TT 14.0

Spanish (children) At 4 years

Egyptian (children) At 2 years

(Children) At 5 years

T677A1298 (+) 74.0 117

3R/3R-negative Canadian (children) At 5 years

T677A1298 (-) French–Canadian origin

**Table 4.** Genetic polymorphism and its relationship to survival in ALL

(children) At 5 years

A/G + A/A 28.0 34

A/G + A/A 42.0 50

A/G + A/A 75.0 305

A/G + A/A 76.0 143

GT+TT >90.0 116 **-317A>G polymorphism in DHFR gene**

A/G + G/G 41.0 56

A/G + G/G 76.0 31

C/T + T/T 38.0 60

3R/3R-positive 71.0 66

3R/3R 50 **677C>T polymorphism in MTHFR gene**

TT 52.0 35

TT 50.0 4 **T677A1298 haplotype of the MTHFR gene**

**829C>T polymorphism in DHFR gene**

**Polymorphism in TS gene**

**-354G>T polymorphism in GGH gene**

**% of Overall Survival**

59.0 13

76.0 20

97.0 160

89.0 61

90.0 123

78.0 14

92.0 24

80.0 10

82.0 193

98.0 106

90.9 22

89.0 84

155

87.0 68.0

55.0

**Number of patients**

**Ref.**

[102]

[103]

[104]

[93]

[99]

[105]

[106]

[105]

[107]

[108]

[110]

[111]

[112]

118 [109]

DHFR is responsible to catalyze the reduction of dihydrofolate (DHF) to tetrahydrofolate (THF) [113]. The major mechanism of MTX action involves competitive inhibition of DHFR, leading to the impaired regeneration of THF from DHF; essential for the biosynthesis of pu‐ rines and thymidylate, thus it also blocks the novo synthesis of DNA [114, 115].

Changes in the levels of DHFR expression and consequently in the sensitivity to MTX can also be due to single SNPs, particularly those located in the regulatory elements [105]. The C829T SNP is located at the 223 nucleotide downstream from the stop codon between the first and second polyadenylation sites in the 3'UTR of the DHFR gene, which leads to the stability of mRNA [116]. A previous study reported that the -A317G SNP in the DHFR pro‐ moter region results in higher transcriptional activity [106]. Recently demonstrated an asso‐ ciation between G/G and T/T genotypes of the -A317G and C829T polymorphisms and reduced survival in pediatric patients with ALL (Table 4).

## **16. Thymidylate Synthase (TS)**

The TS is a key enzyme in the nucleotide biosynthesis and important target of several che‐ motherapeutics. TS provides the only source for de novo thymidylate production by catalyz‐ ing the methylation of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate (dTMP) [107]. TS is efficiently inhibited by the uracil analog, 5-fluorouracil (5-FU) and MTX, used for many years as a treatment for a variety of cancers.

The most common polymorphism in TS is a unique double (2R) or triple (3R) 28-bp tandem repeat sequence in the 5' untranslated region (5'-UTR) of the TS gene also called TS enhancer region (TSER), immediately upstream from the initiation site, which influences protein ex‐ pression in cancer cells [117]. The presence of a triple versus double 28-bp repeat in the en‐ hancer region has been associated with an increased TS expression both in *in vivo* and *in vitro* studies [118, 119].

Previous studies have shown that pediatric patients who were homozygous for the triple re‐ peat (3R/3R) had a poorer prognostic (odds ratio 4.1, 95% CI 1 9–9 0, p=0 001) [108] and shorter survival than those patients with other genotypes (Table 4).

## **17. Methylenetetrahydrofolate Reductase (MTHFR)**

The MTHFR is a key folate enzyme that catalyzes the conversion of 5,10-methylenetetrahy‐ drofolate to 5-methyltetrahydrofolate in the folic acid cycle, and is interrupted by metho‐ trexate (MTX), a critical chemotherapy agent in ALL therapy [120].

Despite the fact that several MTHFR polymorphisms have been described thus far, only two polymorphisms, C677T and A1298C, have been intensively investigated. The C-to-T transi‐ tion at the nucleotide position 677 in exon 4 of MTHFR generates an alanine-to-valine substi‐ tution at amino acid 222 [121]. As a result, carriers of the MTHFR 677TT genotype possess a thermolabile enzyme of reduced activity [122]. The second most studied polymorphism in MTHFR is an A-to-C transversion substitution at nucleotide 1,298 (exon 7) that results in an amino acid substitution of glutamate for alanine at codon 429 [123]. Once this amino acid substitution takes place at the S-adenosylmethionine regulatory domain of the MTHFR, the A1298C polymorphism also generates an enzyme with a decreased activity [123]. Other in‐ vestigators have reported that A1298C and C677T polymorphisms in MTHFR gene are asso‐ ciated with disease outcomes and survival both in children and adults (table 4).

**19. Multidrug Resistance-Associated Protein 1 (MRP1/ABCC1)**

vincristine, etoposide, 6-mercaptopurine, and methotrexate [131-134].

, Yazmín Gómez-Gómez1

\*Address all correspondence to: leyvamarco13@gmail.com

dren and adults (Table 5).

with ALL.

**Author details**

D.F., Mexico

Jorge Organista-Nava1

Marco Antonio Leyva-Vázquez2\*

Chilpancingo, Guerrero, Mexico

**20. Summary and future directions**

Multidrug resistance (MDR) is one of the major obstacles in cancer chemotherapy. Over-ex‐ pression of ATP-binding cassette (ABC) transporters, such as P-glycoprotein (Pgp/MDR1/ ABCB1) and multidrug resistance-associated protein 1 (MRP1/ABCC1), have been shown to cause MDR in model cell lines and in clinical settings [128-130]. Currently, eight MRP genes have been identified, of which the MRP transporters (MRP1-6) are known to be involved in extruding substrates that are generally used in the treatment of ALL, including doxorubicin,

Recent studies have shown that in ALL patients, high expression of MRP1, is a highly signif‐ icant indicator of poor response to chemotherapy and poor overall survival in both in chil‐

Several clinical and biological features have been associated with the improved survival of patients with ALL, including age, sex, WBC, race/ethnicity, immunophenotype, recurrent chromosomal abnormalities, and genetics polymorphisms. The application of risk-stratified therapy utilizing these prognostic factors has resulted in long-term event-free survival in up to 80-85% of patients with ALL. Further improvement in outcome will require, in part, the discovery of novel prognostic factors, (such as, genetic variation in the folate pathway, transport of drugs, as well as miRNAs expression) to identify the 15-20% of patients who are not cured with current therapies. Recent advances in our understanding of underlying leu‐ kemia biology, including the identification of prognostically distinctive subsets of patients, and of host pharmacogenomics may allow for more precise risk stratification and more tar‐ geted, individualized treatment planning that will lead to higher survival of the patients

1 Institute of Cellular Physiology, National Autonomous University of Mexico (UNAM),

2 Molecular Biomedicine Laboratory, School of Biological Sciences, Guerrero State University,

, Berenice Illades-Aguiar2

and

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

251

The overall survival rate of MTHFR 677TT and 1298CC carriers was lower than that of pa‐ tients carrying MTHFR C or A alleles respectively. A limited amount of evidence has been reported on the influence of MTHFR polymorphisms on survival.

## **18. Methylenetetrahydrofolate Dehydrogenase (MTHFD1)**

*MTHFD1 i*s an enzyme involved in folate metabolism, which plays an important role in the generation of the 5,10-methylene-THF and 10-formyl-THF. The last two are the donor cofac‐ tors for de novo purine and pyrimidine biosynthesis and, thus, for the biosynthesis of DNA [124]. The G to A substitution at position 1958 of the MTHFD1 gene, causing an alanine to glycine substitution at codon 653 located within the 10-formyl-THF synthetase enzyme do‐ main, which reduces the enzyme's activity [124].

A analysis of 201 children treated with methotrexate showed that patients with the MTHFD1 A1958 variant had a remarkably lower probability of 5-year post-treatment sur‐ vival, compared to subjects with no event-predisposing genotypes (45.0% vs 95.0%, p=0.0002) [112].


**Table 5.** Expression of MRP1 and its relationship to survival in ALL

## **19. Multidrug Resistance-Associated Protein 1 (MRP1/ABCC1)**

Multidrug resistance (MDR) is one of the major obstacles in cancer chemotherapy. Over-ex‐ pression of ATP-binding cassette (ABC) transporters, such as P-glycoprotein (Pgp/MDR1/ ABCB1) and multidrug resistance-associated protein 1 (MRP1/ABCC1), have been shown to cause MDR in model cell lines and in clinical settings [128-130]. Currently, eight MRP genes have been identified, of which the MRP transporters (MRP1-6) are known to be involved in extruding substrates that are generally used in the treatment of ALL, including doxorubicin, vincristine, etoposide, 6-mercaptopurine, and methotrexate [131-134].

Recent studies have shown that in ALL patients, high expression of MRP1, is a highly signif‐ icant indicator of poor response to chemotherapy and poor overall survival in both in chil‐ dren and adults (Table 5).

## **20. Summary and future directions**

Several clinical and biological features have been associated with the improved survival of patients with ALL, including age, sex, WBC, race/ethnicity, immunophenotype, recurrent chromosomal abnormalities, and genetics polymorphisms. The application of risk-stratified therapy utilizing these prognostic factors has resulted in long-term event-free survival in up to 80-85% of patients with ALL. Further improvement in outcome will require, in part, the discovery of novel prognostic factors, (such as, genetic variation in the folate pathway, transport of drugs, as well as miRNAs expression) to identify the 15-20% of patients who are not cured with current therapies. Recent advances in our understanding of underlying leu‐ kemia biology, including the identification of prognostically distinctive subsets of patients, and of host pharmacogenomics may allow for more precise risk stratification and more tar‐ geted, individualized treatment planning that will lead to higher survival of the patients with ALL.

## **Author details**

tion at the nucleotide position 677 in exon 4 of MTHFR generates an alanine-to-valine substi‐ tution at amino acid 222 [121]. As a result, carriers of the MTHFR 677TT genotype possess a thermolabile enzyme of reduced activity [122]. The second most studied polymorphism in MTHFR is an A-to-C transversion substitution at nucleotide 1,298 (exon 7) that results in an amino acid substitution of glutamate for alanine at codon 429 [123]. Once this amino acid substitution takes place at the S-adenosylmethionine regulatory domain of the MTHFR, the A1298C polymorphism also generates an enzyme with a decreased activity [123]. Other in‐ vestigators have reported that A1298C and C677T polymorphisms in MTHFR gene are asso‐

The overall survival rate of MTHFR 677TT and 1298CC carriers was lower than that of pa‐ tients carrying MTHFR C or A alleles respectively. A limited amount of evidence has been

*MTHFD1 i*s an enzyme involved in folate metabolism, which plays an important role in the generation of the 5,10-methylene-THF and 10-formyl-THF. The last two are the donor cofac‐ tors for de novo purine and pyrimidine biosynthesis and, thus, for the biosynthesis of DNA [124]. The G to A substitution at position 1958 of the MTHFD1 gene, causing an alanine to glycine substitution at codon 653 located within the 10-formyl-THF synthetase enzyme do‐

A analysis of 201 children treated with methotrexate showed that patients with the MTHFD1 A1958 variant had a remarkably lower probability of 5-year post-treatment sur‐ vival, compared to subjects with no event-predisposing genotypes (45.0% vs 95.0%,

> **% of Overall Survival**

> > 81.0

87.2

80.0

>85.0 24

**Number of patients**

**Ref.**

[125]

150 [126]

56 [127]

49 [127]

ciated with disease outcomes and survival both in children and adults (table 4).

reported on the influence of MTHFR polymorphisms on survival.

250 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

main, which reduces the enzyme's activity [124].

**Expression Population Survival estimated**

Korean (Children and Adults At 2 years

Brazilian (Childen) At 5 years

High 54.0

European (Children) At 5 years

High 60.0

European (Adults) At 5 years

High 52.0

**Table 5.** Expression of MRP1 and its relationship to survival in ALL

Positive <55.0 8

p=0.0002) [112].

Negative

Low

Low

Low

**18. Methylenetetrahydrofolate Dehydrogenase (MTHFD1)**

Jorge Organista-Nava1 , Yazmín Gómez-Gómez1 , Berenice Illades-Aguiar2 and Marco Antonio Leyva-Vázquez2\*

\*Address all correspondence to: leyvamarco13@gmail.com

1 Institute of Cellular Physiology, National Autonomous University of Mexico (UNAM), D.F., Mexico

2 Molecular Biomedicine Laboratory, School of Biological Sciences, Guerrero State University, Chilpancingo, Guerrero, Mexico

## **References**

[1] Robison LL. Late Effects of Acute Lymphoblastic Leukemia Therapy in Patients Di‐ agnosed at 0-20 Years of Age. ASH Education Program Book 2011, 2011;2011(1): 238-42.

adolescents with B-cell precursor acute lymphoblastic leukemia: results in 3184 pa‐

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

253

[12] Moorman AV, Ensor HM, Richards SM, Chilton L, Schwab C, Kinsey SE, et al. Prog‐ nostic effect of chromosomal abnormalities in childhood B-cell precursor acute lym‐ phoblastic leukaemia: results from the UK Medical Research Council ALL97/99

[13] Shaikh M U, Ali N ASN, M K. Outcome of adult patients with acute lymphoblastic leukaemia receiving the MRC UKALL XII protocol: a tertiary care centre experience.

[14] Durrant IJ, Richards SM, Prentice HG, Goldstone AH. The medical research council trials in adult acute lyphoblastic leukemia. Hematology/Oncology Clinics of North

[15] Larson R. Recent clinical trials in acute lyphoblastic leukemia by the cancer and leu‐ kemia group B Hematology/Oncology Clinics of North America 2000;14(6):1367-79.

[16] Hunger SP, Lu X, Devidas M, Camitta BM, Gaynon PS, Winick NJ, et al. Improved survival for children and adolescents with acute lymphoblastic leukemia between 1990 and 2005: a report from the hildren's oncology group. J Clin Oncol

[17] Pui C-H, Evans WE. Treatment of Acute Lymphoblastic Leukemia. New England

[18] Hunault-Berger M, Chevallier P, Delain M, Bulabois C-E, Bologna S, Bernard M, et al. Changes in antithrombin and fibrinogen levels during induction chemotherapy with L-asparaginase in adult patients with acute lymphoblastic leukemia or lymphoblastic lymphoma. Use of supportive coagulation therapy and clinical outcome: the CAPE‐

[19] Holmes L, Hossain J, desVignes-Kendrick M, Opara F. Sex variability in pediatric

[20] Moorman AV, Richards SM, Martineau M, Cheung KL, Robinson HM, Jalali GR, et al. Outcome heterogeneity in childhood high-hyperdiploid acute lymphoblastic leu‐

[21] Pui CH, Boyett JM, Relling MV, Harrison PL, Rivera GK, Behm FG, et al. Sex differ‐ ences in prognosis for children with acute lymphoblastic leukemia. Journal of Clini‐

[22] Horibe K, Hara J, Yagi K, Tawa A, Komada Y, Oda M, et al. Prognostic factors in childhood acute lymphoblastic leukemia in Japan. International Journal of Hematolo‐

[23] [23] Yanada M, Jinnai I, Takeuchi J, Ueda T, Miyawaki S, Tsuzuki M, et al. Clinical features and outcome of T-lineage acute lymphoblastic leukemia in adults: A low ini‐

leukemia survival: Large cohort evidence. ISRN Oncology 2012:1-9.

tients of the AIEOP-BFM ALL 2000 study. Blood 2010;115(16):3206-14.

randomised trial. The Lancet Oncology 2010;11(5):429-38.

Singapore Medical Journal 2011;52(5):370-74.

America 2000;14(6):1327-52.

2012;10;30(14):1663-9.

Journal of Medicine 2006;354(2):166-78.

kemia. Blood 2003;102(8):2756-62.

cal Oncology 1999;17(3):818-24.

gy 2000;72(1):61-8.

LAL study. Haematologica 2008, 2008;93(10):1488-94.


adolescents with B-cell precursor acute lymphoblastic leukemia: results in 3184 pa‐ tients of the AIEOP-BFM ALL 2000 study. Blood 2010;115(16):3206-14.

[12] Moorman AV, Ensor HM, Richards SM, Chilton L, Schwab C, Kinsey SE, et al. Prog‐ nostic effect of chromosomal abnormalities in childhood B-cell precursor acute lym‐ phoblastic leukaemia: results from the UK Medical Research Council ALL97/99 randomised trial. The Lancet Oncology 2010;11(5):429-38.

**References**

238-42.

2009;113(7):1408-11.

2005;130(2):166-73.

ers & Prevention 2009, 2009;18(4):1033-40.

International Journal of Hematology 2000;72:61-8.

kemia Research 2007;31(7):907-14.

2007;370(9583):240-50.

1646-54.

[1] Robison LL. Late Effects of Acute Lymphoblastic Leukemia Therapy in Patients Di‐ agnosed at 0-20 Years of Age. ASH Education Program Book 2011, 2011;2011(1):

[2] Pulte D, Gondos A, Brenner H. Improvement in survival in younger patients with acute lymphoblastic leukemia from the 1980s to the early 21st century. Blood 2009,

[3] Smith MA, Seibel NL, Altekruse SF, Ries LAG, Melbert DL, O'Leary M, et al. Out‐ comes for Children and Adolescents With Cancer: Challenges for the Twenty-First

[4] Nachman J. Clinical characteristics, biologic features and outcome for young adult patients with acute lymphoblastic leukaemia. British Journal of Haematology

[5] Stock W, La M, Sanford B, Bloomfield CD, Vardiman JW, Gaynon P, et al. What de‐ termines the outcomes for adolescents and young adults with acute lymphoblastic leukemia treated on cooperative group protocols? A comparison of Children's Can‐ cer Group and Cancer and Leukemia Group B studies. Blood 2008, 2008;112(5):

[6] Mariotto AB, Rowland JH, Yabroff KR, Scoppa S, Hachey M, Ries L, et al. Long-Term Survivors of Childhood Cancers in the United States. Cancer Epidemiology Biomark‐

[7] Yanada M, Jinnai I, Takeuchi J, Ueda T, Miyawaki S, Tsuzuki M, et al. Clinical fea‐ tures and outcome of T-lineage acute lymphoblastic leukemia in adults: A low initial white blood cell count, as well as a high count predict decreased survival rates. Leu‐

[8] Keizo Horibe a, Junichi Hara, Keiko Yagi, Akio Tawa, Yoshihiro Komada, Megumi Oda, et al. Prognostic Factors in Childhood Acute Lymphoblastic Leukemia in Japan.

[9] Hilden JM, Dinndorf PA, Meerbaum SO, Sather H, Villaluna D, Heerema NA, et al. Analysis of prognostic factors of acute lymphoblastic leukemia in infants: report on CCG 1953 from the Children's Oncology Group. Blood 2006, 2006;108(2):441-51.

[10] Pieters R, Schrappe M, De Lorenzo P, Hann I, De Rossi G, Felice M, et al. A treatment protocol for infants younger than 1 year with acute lymphoblastic leukaemia (Inter‐ fant-99): an observational study and a multicentre randomised trial. The Lancet

[11] Conter V, Bartram CR, Valsecchi MG, Schrauder A, Panzer-Grümayer R, Möricke A, et al. Molecular response to treatment redefines all prognostic factors in children and

Century. Journal of Clinical Oncology 2010, 2010;28(15):2625-34.

252 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic


tial white blood cell count, as well as a high count predict decreased survival rates. Leukemia Research 2007;31(7):907-14.

PHO-ALL-1992 protocol: frequent late relapses but good overall survival. British

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

255

[36] Bhojwani D, Pei D, Sandlund JT, Jeha S, Ribeiro RC, Rubnitz JE, et al. ETV6-RUNX1 positive childhood acute lymphoblastic leukemia: improved outcome with contem‐

[37] Gandemer V, Chevret S, Petit A, Vermylen C, Leblanc T, Michel G, et al. Excellent prognosis of late relapses of ETV6/RUNX1-positive childhood acute lymphoblastic leukemia: lessons from the FRALLE 93 protocol. Haematologica 2012;DOI: 10.3324/

[38] Ribera JM, Oriol A, González M, Vidriales B, Brunet S, Esteve J, et al. Concurrent in‐ tensive chemotherapy and imatinib before and after stem cell transplantation in new‐ ly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia. Final

[39] Aricó M, Valsecchi MG, Camitta B, Schrappe M, Chessells J, Baruchel A, et al. Out‐ come of treatment in children with Philadelphia chromosome-positive acute lympho‐

[40] Schultz KR, Bowman WP, Aledo A, Slayton WB, Sather H, Devidas M, et al. Im‐ proved early event-free survival with imatinib in Philadelphia chromosome-positive acute lymphoblastic leukemia: A Children's Oncology Group study. Journal of Clini‐

[41] Yanada M, Takeuchi J, Sugiura I, Akiyama H, Usui N, Yagasaki F, et al. Karyotype at diagnosis is the major prognostic factor predicting relapse-free survival for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia treated with

[42] Bassan R, Spinelli O, Oldani E, Intermesoli T, Tosi M, Peruta B, et al. Improved risk classification for risk-specific therapy based on the molecular study of minimal resid‐ ual disease (MRD) in adult acute lymphoblastic leukemia (ALL). Blood 2009;113(18):

[43] Kosaka Y, Koh K, Kinukawa N, Wakazono Y, Isoyama K, Oda T, et al. Infant acute lymphoblastic leukemia with MLL gene rearrangements: outcome following inten‐ sive chemotherapy and hematopoietic stem cell transplantation. Blood 2004;104(12):

[44] Moorman AV, Harrison CJ, Buck GAN, Richards SM, Secker-Walker LM, Martineau M, et al. Karyotype is an independent prognostic factor in adult acute lymphoblastic leukemia (ALL): analysis of cytogenetic data from patients treated on the Medical Research Council (MRC) UKALLXII/Eastern Cooperative Oncology Group (ECOG)

[45] del Carmen Chillon M, Gomez-Casares MT, Lopez-Jorge CE, Rodriguez-Medina C, Molines A, Sarasquete ME, et al. Prognostic significance of FLT3 mutational status

imatinib-combined chemotherapy. Haematologica 2008;93(2):287-90.

blastic leukemia. New England Journal of Medicine 2000;342(14):998-1006.

results of the CSTIBES02 trial. Haematologica 2010;95(1):87-95.

Journal of Haematology 2008;140(6):665-72.

porary therapy. Leukemia 2012;26(2):265-70.

haematol.2011.059584.

cal Oncology 2009;27(31):5175-81.

2993 trial. Blood 2007;109(8):3189-97.

4153-62.

3527-34.


PHO-ALL-1992 protocol: frequent late relapses but good overall survival. British Journal of Haematology 2008;140(6):665-72.

[36] Bhojwani D, Pei D, Sandlund JT, Jeha S, Ribeiro RC, Rubnitz JE, et al. ETV6-RUNX1 positive childhood acute lymphoblastic leukemia: improved outcome with contem‐ porary therapy. Leukemia 2012;26(2):265-70.

tial white blood cell count, as well as a high count predict decreased survival rates.

[24] [24] Park J, Park SS, Lim YT. A clinical characteristics and prognosis in children of acute lymphoblastic leukemia with hyperleukocytosis. Clinical Pediatric Hematolo‐

[25] Friedmann AM, Weinstein HJ. The role of prognostic features in the treatment of

[26] Wood AJJ, Pui CH, Evans WE. Acute lymphoblastic leukemia. New England Journal

[27] Ribeiro RC, Broniscer A, Rivera GK, Hancock ML, Raimondi SC, Sandlund JT, et al. Philadelphia chromosome-positive acute lymphoblastic leukemia in children: dura‐ ble responses to chemotherapy associated with low initial white blood cell counts. Leukemia: official journal of the Leukemia Society of America, Leukemia Research

[28] Schrappe M, Arico M, Harbott J, Biondi A, Zimmermann M, Conter V, et al. Philadel‐ phia chromosome-positive (Ph+) childhood acute lymphoblastic leukemia: good ini‐ tial steroid response allows early prediction of a favorable treatment outcome. Blood

[29] Kent EE, Sender LS, Largent JA, Anton-Culver H. Leukemia survival in children, adolescents, and young adults: influence of socioeconomic status and other demo‐ graphic factors. Cancer Causes & Control: An International Journal of Studies of Can‐

[30] Bhatia S, Sather HN, Heerema NA, Trigg ME, Gaynon PS, Robison LL. Racial and ethnic differences in survival of children with acute lymphoblastic leukemia. Blood

[31] Kadan-Lottick Ns NKKBSGJG. SUrvival variability by race and ethnicity in child‐

[32] Pui CH, Sandlund JT, Pei D, Rivera GK, Howard SC, Ribeiro RC, et al. Results of therapy for acute lymphoblastic leukemia in black and white children. JAMA

[33] Kadan-Lottick NS, Ness KK, Bhatia S, Gurney JG. Survival variability by race and ethnicity in childhood acute lymphoblastic leukemia. JAMA 2003;290(15):2008-14.

[34] Zen PRG, Capra MEZ, Silla LcMR, Loss JF, Fernandes MrS, Jacques SMC, et al. ETV6/RUNX1 fusion lacking prognostic effect in pediatric patients with acute lym‐

[35] Forestier E, Heyman M, Andersen MK, Autio K, Blennow E, Borgström G, et al. Out‐ come of ETV6/RUNX1-positive childhood acute lymphoblastic leukaemia in the NO‐

phoblastic leukemia. Cancer Genetics and Cytogenetics 2009;188:112-7.

hood acute lymphoblastic leukemia. JAMA 2003;290(15):2008-14.

childhood acute lymphoblastic leukemia. The Oncologist 2000;5(4):321-8.

Leukemia Research 2007;31(7):907-14.

254 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

gy-Oncology 2006;13(1):1-8.

of Medicine 1998;339(9):605-15.

Fund, UK 1997;11(9):1493.

cer in Human Populations 2009;20(8):1409-20.

1998;92(8):2730-41.

2002;100(6):1957-64.

2003;290(15):2001-7.


and expression levels in MLL-AF4+ and MLL-germline Acute Lymphoblastic leuke‐ mia. Leukemia 2012.

[57] Borowitz MJ, Devidas M, Hunger SP, Bowman WP, Carroll AJ, Carroll WL, et al. Clinical significance of minimal residual disease in childhood acute lymphoblastic leukemia and its relationship to other prognostic factors: a Children's Oncology

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

257

[58] Nowell PC, Hungerford DA. A minute chromosome in human chronic granulocytic

[59] Rowley JD. A new consistent chromosomal adnormality in chronic myelogeneus leu‐ kaemia identified by quinacrine fluorescence and Giemsa staining Nature

[60] Gleißner B, Gökbuget N, Bartram CR, Janssen B, Rieder H, Janssen JWG, et al. Lead‐ ing prognostic relevance of the BCR-ABL translocation in adult acute B-lineage lym‐ phoblastic leukemia: a prospective study of the German Multicenter Trial Group and

[61] Schlieben S, Borkhardt A, Reinisch I, Ritterbach J, Janssen JW, Ratei R, et al. Incidence and clinical outcome of children with BCR/ABL-positive acute lymphoblastic leuke‐ mia (ALL). A prospective RT-PCR study based on 673 patients enrolled in the Ger‐ man pediatric multicenter therapy trials ALL-BFM-90 and CoALL-05-92. Leukemia

[62] Melo JV. The diversity of BCR-ABL fusion proteins and their relationship to leuke‐

[63] Russo C, Carroll A, Kohler S, Borowitz M, Amylon M, Homans A, et al. Philadelphia chromosome and monosomy 7 in childhood acute lymphoblastic leukemia: a Pedia‐

[64] Kantarjian HM, Talpaz M, Dhingra K, Estey E, Keating MJ, Ku S, et al. Significance of the P210 versus P190 molecular abnormalities in adults with Philadelphia chromo‐

[65] Melo JV, Gordon DE, Tuszynski A, Dhut S, Young BD, Goldman JM. Expression of the ABL-BCR fusion gene in Philadelphia-positive acute lymphoblastic leukemia.

[66] Schrappe M, Aricó M, Harbott J, Biondi A, Zimmermann M, Conter V, et al. Philadel‐ phia chromosome-positive (Ph+) childhood acute lymphoblastic leukemia: good ini‐ tial steroid response allows early prediction of a favorable treatment outcome. Blood

[67] Ribeiro RC, Broniscer A, Rivera GK, Hancock ML, Raimondi SC, Sandlund JT, et al. Philadelphia chromosome-positive acute lymphoblastic leukemia in children: dura‐ ble responses to chemotherapy associated with low initial white blood cell counts.

[68] Thomas X, Thiebaut A, Olteanu N, Danaila C, Charrin C, Archimbaud E, et al. Phila‐ delphia chromosome positive adult acute lymphoblastic leukemia: characteristics,

confirmed polymerase chain reaction analysis. Blood, 2002;99(5):1536-43.

Group study. Blood 2008;111(12):5477-85.

mia phenotype. Blood 1996;88(7):2375-84.

tric Oncology Group study. Blood 1991;77(5):1050-6.

some-positive acute leukemia. Blood 1991;78(9):2411-8.

leukemia. Science 1960;132:1497-501.

1973;243(51):290-93.

1996;10(6):957-63.

Blood 1993;81(10):2488-91.

Leukemia 1997;11(9):1493-6.

1998;92(8):2730.


[57] Borowitz MJ, Devidas M, Hunger SP, Bowman WP, Carroll AJ, Carroll WL, et al. Clinical significance of minimal residual disease in childhood acute lymphoblastic leukemia and its relationship to other prognostic factors: a Children's Oncology Group study. Blood 2008;111(12):5477-85.

and expression levels in MLL-AF4+ and MLL-germline Acute Lymphoblastic leuke‐

[46] Kager L, Lion T, Attarbaschi A, Koenig M, Strehl S, Haas OA, et al. Incidence and outcome of TCF3-PBX1-positive acute lymphoblastic leukemia in Austrian children.

[47] Jeha S, Pei D, Raimondi SC, Onciu M, Campana D, Cheng C, et al. Increased risk for CNS relapse in pre-B cell leukemia with the t(1;19)/TCF3-PBX1. Leukemia 2009;23(8):

[48] Moorman AV, Chilton L, Wilkinson J, Ensor HM, Bown N, Proctor SJ. A populationbased cytogenetic study of adults with acute lymphoblastic leukemia. Blood

[49] Swerdlow SH, Cancer. IAfRo, Organization. WH. WHO classification of tumours of

[50] Goldberg JM, Silverman LB, Levy DE, Dalton VK, Gelber RD, Lehmann L, et al. Childhood T-Cell Acute Lymphoblastic Leukemia: The Dana-Farber Cancer Institute Acute Lymphoblastic Leukemia Consortium Experience. Journal of Clinical Oncolo‐

[51] Zhang YL, Zhao WL, Nie SS, Guo DD, Ji ZH, Chai YH. Analysis of Clinical Features and Prognostic Significance of Childhood T-lineage Acute Lymphoblastic Leukemia. Journal of experimental hematology/Chinese Association of Pathophysiology

[52] Dores GM, Devesa SS, Curtis RE, Linet MS, Morton LM. Acute leukemia incidence and patient survival among children and adults in the United States, 2001-2007.

[53] Nordlund J, Kiialainen A, Karlberg O, Berglund EC, Goransson-Kultima H, Sonder‐ kar M, et al. Digital gene expression profiling of primary acute lymphoblastic leuke‐

[54] Forestier E, Andersen MK, Autio K, Blennow E, Borgström G, Golovleva I, et al. Cy‐ togenetic patterns in ETV6/RUNX1-positive pediatric B-cell precursor acute lympho‐ blastic leukemia: A Nordic series of 245 cases and review of the literature. Genes,

[55] Nachman JB, Heerema NA, Sather H, Camitta B, Forestier E, Harrison CJ, et al. Out‐ come of treatment in children with hypodiploid acute lymphoblastic leukemia. Blood

[56] Rubnitz JE, Wichlan D, Devidas M, Shuster J, Linda SB, Kurtzberg J, et al. Prospec‐ tive Analysis of TEL Gene Rearrangements in Childhood Acute Lymphoblastic Leu‐ kemia: A Children's Oncology Group Study. Journal of Clinical Oncology

haematopoietic and lymphoid tissues. Book 2008;4th ed.: 380-428.

mia. Leukemia 2012.

2010;115(2):206-14.

gy 2003, 2003;21(19):3616-22.

Blood 2011, 2012;119(1):34-43.

mia cells. Leukemia 2012;26(6):1218-27.

Chromosomes and Cancer 2007;46(5):440-50.

2011;19(6):1496-500.

2007;110(4):1112-5.

2008;26(13):2186-91.

1406-9.

Haematologica 2007;92(11):1561-4.

256 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic


prognostic factors and treatment outcome. Hematology and Cell Therapy 1998;40(3): 119-28.

context of contemporary therapies: a report from the Children's Cancer Group. Jour‐

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

259

[81] Chiaretti S, Foá R. T-cell acute lymphoblastic leukemia. Haematologica 2009;94(2):

[82] Sen L, Borella L. Clinical Importance of Lymphoblasts with T Markers in Childhood

[83] Sallan SE. T-cell acute lymphoblastic leukemia in children. Haematology and Blood

[84] Bergeron J, Clappier E, Radford I, Buzyn A, Millien C, Soler G, et al. Prognostic and oncogenic relevance of TLX1/HOX11 expression level in T-ALLs. Blood 2007;110(7):

[85] Cavé H, Suciu S, Preudhomme C, Poppe B, Robert A, Uyttebroeck A, et al. Clinical significance of HOX11L2 expression linked to t (5; 14)(q35; q32), of HOX11 expres‐ sion, and of SIL-TAL fusion in childhood T-cell malignancies: results of EORTC stud‐

[86] Ferrando AA, Neuberg DS, Dodge RK, Paietta E, Larson RA, Wiernik PH, et al. Prog‐ nostic importance of TLX1 (HOX11) oncogene expression in adults with T-cell acute

[88] Tiphaine Adam de Beaumais, Jacqz-Aigrain E. Intracellular disposition of methotrex‐ ate in acute lymphoblastic leukemia in children. Current Drug Metabolism

[89] Lennard L. Therapeutic drug monitoring of cytotoxic drugs. Br J Clin Pharmacol

[90] Mikkelsen Torben S TCF, Yang Jun J, Ulrich Cornelia M, French Deborah, Zaza Gian‐ luigi, Dunnenberger Henry M, Marsh Sharon, McLeod Howard L, Giacomini Kathy, Becker Mara L, Gaedigk Roger, Leeder James Steven, Kager Leo, Relling Mary V, Evans William, Klein Teri E, Altman Russ B. "PharmGKB summary: methotrexate

[91] Karathanasis NV, Choumerianou DM, Kalmanti M. Gene polymorphisms in child‐

[92] Sierra E, Goldman ID. Recent advances in the understanding of the mechanism of membrane transport of folates and antifolates. Seminars Oncology 1999;26:11-23.

[93] Laverdiére C, Chiasson S, Costea I, Moghrabi A, Krajinovic M. Polymorphism G80A in the reduced folate carrier gene and its relationship to methotrexate plasma levels and outcome of childhood acute lymphoblastic leukemia. Blood 2002;100(10):3832-4.

[87] Zhao R, Goldman ID. Resistance to antifolates. Oncogene 2003;22(47):7431-57.

Acute Leukemia. New England Journal of Medicine 1975;292(16):828-32.

nal of Clinical Oncology 1998;16(2):527-35.

ies 58881 and 58951. Blood 2004;103(2):442-50.

pathway" Pharmacogenetics and genomics (2011).

hood ALL. Pediatric Blood & Cancer 2009;52(3):318-23.

lymphoblastic leukaemia. The Lancet 2004;363(9408):535-6.

Transfusion 1981;26:121-3.

160-2.

2324-30.

2012;13(6):822-34.

2001;52:75–87.


context of contemporary therapies: a report from the Children's Cancer Group. Jour‐ nal of Clinical Oncology 1998;16(2):527-35.

[81] Chiaretti S, Foá R. T-cell acute lymphoblastic leukemia. Haematologica 2009;94(2): 160-2.

prognostic factors and treatment outcome. Hematology and Cell Therapy 1998;40(3):

[69] Pui CH, Relling MV, Downing JR. Acute lymphoblastic leukemia. New England

[70] Pui CH, Frankel LS, Carroll AJ, Raimondi SC, Shuster JJ, Head DR, et al. Clinical characteristics and treatment outcome of childhood acute lymphoblastic leukemia with the t (4; 11)(q21; q23): a collaborative study of 40 cases. Blood 1991;77(3):440-7. [71] Cimino G, Elia L, Mancini M, Annino L, Anaclerico B, Fazi P, et al. Clinico-biologic features and treatment outcome in the GIMEMA 0496 study: absence of the ALL1/AF4 and of the BCR/ABL fusion genes correlates with a significantly better

[72] Mancini M, Scappaticci D, Cimino G, Nanni M, Derme V, Elia L, et al. A comprehen‐ sive genetic classification of adult acute lymphoblastic leukemia (ALL): analysis of

[73] Marchesi F, Girardi K, Avvisati G. Pathogenetic, Clinical, and Prognostic Features of Adult t (4; 11)(q21; q23)/MLL-AF4 Positive B-Cell Acute Lymphoblastic Leukemia.

[74] [74] Rubnitz JE, Camitta BM, Mahmoud H, Raimondi SC, Carroll AJ, Borowitz MJ, et al. Childhood Acute Lymphoblastic Leukemia With the MLL-ENL Fusion and t(11;19)(q23;p13.3) Translocation. Journal of Clinical Oncology 1999;17(1):191-6. [75] Moorman AV, Ensor HM, Richards SM, Chilton L, Schwab C, Kinsey SE, et al. Prog‐ nostic effect of chromosomal abnormalities in childhood B-cell precursor acute lym‐ phoblastic leukaemia: results from the UK Medical Research Council ALL97/99

[76] Schmiegelow K, Forestier E, Hellebostad M, Heyman M, Kristinsson J, Soderhall S, et al. Long-term results of NOPHO ALL-92 and ALL-2000 studies of childhood acute

[77] Mellentin JD, Murre C, Donlon TA, McCaw PS, Smith SD, Carroll AJ, et al. The gene for enhancer binding proteins E12/E47 lies at the t (1; 19) breakpoint in acute leuke‐

[78] Andersen MK, Autio K, Barbany G, Borgström G, Cavelier L, Golovleva I, et al. Paediatric B-cell precursor acute lymphoblastic leukaemia with t(1;19)(q23;p13): clini‐ cal and cytogenetic characteristics of 47 cases from the Nordic countries treated ac‐ cording to NOPHO protocols. British Journal of Haematology 2011;155:235–43 [79] Secker-Walker LM, Berger R, Fenaux P, Lai JL, Nelken B, Garson M, et al. Prognostic significance of the balanced t (1; 19) and unbalanced der (19) t (1; 19) translocations in

[80] Uckun FM, Sensel MG, Sather HN, Gaynon PS, Arthur DC, Lange BJ, et al. Clinical significance of translocation t(1;19) in childhood acute lymphoblastic leukemia in the

119-28.

Journal of Medicine 2004;350(15):1535-48.

258 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

clinical outcome. Blood 2003;102(6):2014-20.

Advances in Hematology 2011:1-8.

mias. Science 1989;246(4928):379-82.

the GIMEMA 0496 protocol. Blood 2005;105(9):3434-41.

randomised trial. The Lancet Oncology;11(5):429-38.

lymphoblastic leukemia. Leukemia 2010;24(2):345-54.

acute lymphoblastic leukemia. Leukemia 1992;6(5):363-9.


[94] Ansari M, Krajinovic M. Pharmacogenomics of acute leukemia. Pharmacogenomics 2007;8(7):817-34.

lymphoblastic leukemia in a Mexican population is affected by dihydrofolate reduc‐ tase gene polymorphisms. Experimental and Therapeutic Medicine 2012;3(4):665-72.

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

261

[106] Dulucq S, St-Onge G, Gagné V, Ansari M, Sinnett D, Labuda D, et al. DNA variants in the dihydrofolate reductase gene and outcome in childhood ALL. Blood

[107] Krajinovic M, Costea I, Primeau M, Dulucq S, Moghrabi A. Combining several poly‐ morphisms of thymidylate synthase gene for pharmacogenetic analysis. Pharmaco‐

[108] Krajinovic M, Costea I, Chiasson S. Polymorphism of the thymidylate synthase gene and outcome of acute lymphoblastic leukaemia. The Lancet 2002;359(9311):1033-4.

[109] Ongaro A, De Mattei M, Della Porta MG, Rigolin GM, Ambrosio C, Di Raimondo F, et al. Gene polymorphisms in folate metabolizing enzymes in adult acute lympho‐ blastic leukemia: effects on methotrexate-related toxicity and survival. Haematologi‐

[110] Salazar J, Altés A, Del Río E, Estella J, Rives S, Tasso M, et al. Methotrexate consolida‐ tion treatment according to pharmacogenetics of MTHFR ameliorates event-free sur‐ vival in childhood acute lymphoblastic leukaemia. The Pharmacogenomics Journal

[111] El-Khodary N, El-Haggar S, Eid M, Ebeid E. Study of the pharmacokinetic and phar‐ macogenetic contribution to the toxicity of high-dose methotrexate in children with

[112] Krajinovic M, Lemieux-Blanchard E, Chiasson S, Primeau M, Costea I, Moghrabi A. Role of polymorphisms in MTHFR and MTHFD1 genes in the outcome of childhood acute lymphoblastic leukemia. The Pharmacogenomics Journal 2004;4(1):66-72.

[113] Wang L, Goodey NM, Benkovic SJ, Kohen A. Coordinated effects of distal mutations on environmentally coupled tunneling in dihydrofolate reductase. Proceedings of the

[114] Volpato JP, Fossati E, Pelletier JN. Increasing Methotrexate Resistance by Combina‐ tion of Active-site Mutations in Human Dihydrofolate Reductase. Journal of Molecu‐

[115] Allemann RK, Evans RM, Tey L-h, Maglia G, Pang J, Rodriguez R, et al. Protein mo‐ tions during catalysis by dihydrofolate reductases. Philosophical Transactions of the

[116] Goto Y, Yue L, Yokoi A, Nishimura R, Uehara T, Koizumi S, et al. A novel singlenucleotide polymorphism in the 3'-untranslated region of the human dihydrofolate reductase gene with enhanced expression. Clinical Cancer Research 2001;7(7):1952-6.

acute lymphoblastic leukemia. Medical Oncology 2011:1-10.

National Academy of Sciences 2006;103(43):15753-8.

Royal Society B: Biological Sciences 2006;361(1472):1317-21.

2008;111(7):3692-700.

ca 2009;94(10):1391-8.

2011;doi:10.1038/tpj.2011.25.

lar Biology 2007;373(3):599-611.

genomics Journal 2005;5(6):374-80.


lymphoblastic leukemia in a Mexican population is affected by dihydrofolate reduc‐ tase gene polymorphisms. Experimental and Therapeutic Medicine 2012;3(4):665-72.

[106] Dulucq S, St-Onge G, Gagné V, Ansari M, Sinnett D, Labuda D, et al. DNA variants in the dihydrofolate reductase gene and outcome in childhood ALL. Blood 2008;111(7):3692-700.

[94] Ansari M, Krajinovic M. Pharmacogenomics of acute leukemia. Pharmacogenomics

[95] Chave KJ, Ryan TJ, Chmura SE, Galivan J. Identification of single nucleotide poly‐ morphisms in the human gamma-glutamyl hydrolase gene and characterization of

[96] Organista-Nava J, Gómez-Gómez Y, Saavedra-Herrera MV, Rivera-Ramírez AB, Ter‐ án-Porcayo MA, Alarcón-Romero LdC, et al. Polymorphisms of the gamma-glutamyl hydrolase gene and risk of relapse to acute lymphoblastic leukemia in Mexico. Leu‐

[97] Cheng Q, Wu B, Kager L, Panetta J, Zheng J, Pui C, et al. A substrate specific func‐ tional polymorphism of human gamma-glutamyl hydrolase alters catalytic activity and methotrexate polyglutamate accumulation in acute lymphoblastic leukaemia

[98] Dervieux T, Kremer J, Lein D, Capps R, Barham R, Meyer G, et al. Contribution of common polymorphisms in reduced folate carrier and gamma-glutamylhydrolase to methotrexate polyglutamate levels in patients with rheumatoid arthritis. Pharmaco‐

[99] Garcia-Bournissen F, Moghrabi A, Krajinovic M. Therapeutic responses in childhood acute lymphoblastic leukemia (ALL) and haplotypes of gamma glutamyl hydrolase

[100] Schneider E, Ryan TJ. Gamma-glutamyl hydrolase and drug resistance. Clinica Chi‐

[101] Chave KJ, Ryan TJ, Chmura SE, Galivan J. Identification of single nucleotide poly‐ morphisms in the human g-glutamyl hydrolase gene and characterization of promot‐

[102] Chiusolo P, Giammarco S, Bellesi S, Metafuni E, Piccirillo N, De Ritis D, et al. The role of MTHFR and RFC1 polymorphisms on toxicity and outcome of adult patients with hematological malignancies treated with high-dose methotrexate followed by

leucovorin rescue. Cancer Chemotherapy and Pharmacology 2012;69(3):691-6. [103] Leyva-Vázquez M, Organista-Nava J, Gómez-Gómez Y, Contreras-Quiroz A, Flores-Alfaro E, Illades-Aguiar B. Polymorphism G80A in the reduced folate carrier gene and its relationship to survival and risk of relapse in acute lymphoblastic leukemia.

[104] Gregers J, Christensen IJ, Dalhoff K, Lausen B, Schroeder H, Rosthoej S, et al. The as‐ sociation of reduced folate carrier 80G> A polymorphism to outcome in childhood acute lymphoblastic leukemia interacts with chromosome 21 copy number. Blood

[105] Gómez-Gómez Y, Organista-Nava J, Saavedra-Herrera MV, Rivera-Ramírez AB, Ter‐ án-Porcayo MA, Alarcón-Romero LdC, et al. Survival and risk of relapse of acute

promoter polymorphisms. Gene 2003;319(0):167-75.

260 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

kemia Research 2009;34(6):728-32.

genetics 2004;14(11):733-9.

mica Acta 2006;374:25-32.

2010;115(23):4671-7.

cells. Pharmacogenetics 2004;14(8):557-67.

(GGH) gene. Leukemia Research 2007;31(7):1023-5.

er polymorphisms. Gene 2003;319(0):167-75.

Journal of Investigative Medicine;2012, 60:1064-7.

2007;8(7):817-34.


[117] Nazki FH, Masood A, Banday MA, Bhat A, Ganai BA. Thymidylate synthase enhanc‐ er region polymorphism not related to susceptibility to acute lymphoblastic leukemia in the Kashmir population. Genetics and Molecular Research 2012;11(2):906-17.

[127] Plasschaert SLA, de Bont ESJM, Boezen M, vander Kolk DM, Daenen SMJG, Faber KN, et al. Expression of Multidrug Resistance-Associated Proteins Predicts Prognosis in Childhood and Adult Acute Lymphoblastic Leukemia. Clinical Cancer Research

Survival of Patients With Acute Lymphoblastic Leukemia

http://dx.doi.org/10.5772/54261

263

[128] Stride BD, Grant CE, Loe DW, Hipfner DR, Cole SPC, Deeley RG. Pharmacological Characterization of the Murine and Human Orthologs of Multidrug-Resistance Pro‐ tein in Transfected Human Embryonic Kidney Cells. Molecular Pharmacology

[129] Breuninger LM, Paul S, Gaughan K, Miki T, Chan A, Aaronson SA, et al. Expression of Multidrug Resistance-associated Protein in NIH/3T3 Cells Confers Multidrug Re‐ sistance Associated with Increased Drug Efflux and Altered Intracellular Drug Distri‐

[130] Conseil G, Deeley RG, Cole SPC. Polymorphisms of MRP1 (ABCC1) and related ATP-dependent drug transporters. Pharmacogenetics and Genomics 2005;15(8):

[131] Belinsky MG, Chen ZS, Shchaveleva I, Zeng H, Kruh GD. Characterization of the drug resistance and transport properties of multidrug resistance protein 6 (MRP6,

[132] Borst P, Evers R, Kool M, Wijnholds J. A family of drug transporters: the multidrug resistance-associated proteins. Journal of the National Cancer Institute

[133] Jedlitschky G, Burchell B, Keppler D. The multidrug resistance protein 5 functions as an ATP-dependent export pump for cyclic nucleotides. The Journal of Biological

[134] Kool M, Van Der Linden M, De Haas M, Scheffer GL, De Vree JML, Smith AJ, et al. MRP3, an organic anion transporter able to transport anti-cancer drugs. Proceedings

of the National Academy of Sciences 1999;96(12):6914-9.

2005;11(24):8661-8.

1997;52(3):344-53.

523-33.

2000;92:1295-302.

bution. Cancer Research 1995;55(22):5342-7.

ABCC6). Cancer Research 2002;62(21):6172.

Chemistry 2000;275(39):30069-74.


[127] Plasschaert SLA, de Bont ESJM, Boezen M, vander Kolk DM, Daenen SMJG, Faber KN, et al. Expression of Multidrug Resistance-Associated Proteins Predicts Prognosis in Childhood and Adult Acute Lymphoblastic Leukemia. Clinical Cancer Research 2005;11(24):8661-8.

[117] Nazki FH, Masood A, Banday MA, Bhat A, Ganai BA. Thymidylate synthase enhanc‐ er region polymorphism not related to susceptibility to acute lymphoblastic leukemia in the Kashmir population. Genetics and Molecular Research 2012;11(2):906-17.

[118] Horie N, Aiba H, Oguro K, Hojo H, Takeishi K. Functional analysis and DNA poly‐ morphism of the tandemly repeated sequences in the 5'-terminal regulatory region of the human gene for thymidylate synthase. Cell Structure and Function 1995;20(3):

[119] Rahimi Z, Ahmadian Z, Akramipour R, Vaisi-Raygani A, Rahimi Z, Parsian A. Thy‐ midylate synthase and methionine synthase polymorphisms are not associated with susceptibility to childhood acute lymphoblastic leukemia in Kurdish population

[120] Aplenc R, Thompson J, Han P, La M, Zhao H, Lange B, et al. Methylenetetrahydrofo‐ late Reductase Polymorphisms and Therapy Response in Pediatric Acute Lympho‐

[121] Guenther BD, Sheppard CA, Tran P, Rozen R, Matthews RG, Ludwig ML. The struc‐ ture and properties of methylenetetrahydrofolate reductase from Escherichia coli suggest how folate ameliorates human hyperhomocysteinemia. Nature Structural &

[122] Frosst P, Blom HJ, Milos R, Goyette P, Sheppard CA, Matthews RG, et al. A candi‐ date genetic risk factor for vascular disease: a common mutation in methylenetetra‐

[123] van der Put NMJ, Gabreëls F, Stevens E, Smeitink JAM, Trijbels FJM, Eskes TKAB, et al. A second common mutation in the methylenetetrahydrofolate reductase gene: an additional risk factor for neural-tube defects? The American Journal of Human

[124] Hol FA, van der Put NMJ, Geurds MPA, Heil SG, Trijbels FJM, Hamel BCJ, et al. Mo‐ lecular genetic analysis of the gene encoding the trifunctional enzyme MTHFD(meth‐ ylenetetrahydrofolate-dehydrogenase, methenyltetrahydrofolate-cyclohydrolase, formyltetrahydrofolate synthetase) in patients with neural tube defects. Clinical Ge‐

[125] Huh HJ, Park CJ, Jang S, Seo EJ, Chi HS, Lee JH, et al. Prognostic significance of mul‐ tidrug resistance gene 1 (MDR1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) mRNA expression in acute leukemia. Journal of Korean

[126] Cortez MAA, Scrideli CA, Yunes JA, Valera ET, Toledo SRC, Pavoni-Ferreira PCB, et al. mRNA expression profile of multidrug resistance genes in childhood acute lym‐ phoblastic leukemia. Low expression levels associated with a higher risk of toxic

from Western Iran. Molecular Biology Reports 2001;39(3):2195-200.

blastic Leukemia. Cancer Research 2005, 65(6):2482-7.

262 Clinical Epidemiology of Acute Lymphoblastic Leukemia - From the Molecules to the Clinic

hydrofolate reductase. Nature Genetics 1995;10(1):111-3.

Molecular Biology 1999;6(4):359-65.

Genetics 1998;62(5):1044-51.

netics 1998;53(2):119-25.

Medical Science 2006;21(2):253-8.

death. Pediatric Blood & Cancer 2009;53(6):996-1004.

191-7.


**Chapter 11**

**Bone Marrow Transplantation (BMT) in Philadelphia-**

Ph+ ALL represents approximately about 25 to 40% of adults patients with ALL. In children, Ph+ ALL is much less common. Different breakpoint in the bcr gene, major and minor, produce fusion genes resulting in either a 210 or a 190 KDa protein respectively. It appears that major breakpoint fusion (p210) originates in hematopoietic stem cells whereas minor breakpoint fusion (p190) has a B cell progenitor origin, suggesting that p190 ALL and p210 Ph+ ALL may be distinct biological and clinical entities. [1] BMT is the first option for consolidation the complete remission in this patients. The proportion of patients able to undergo BMT in CR1 (Complete Remission) has increased with imatinib-based induc‐ tion and early post-remission therapy, and there is currently no evidence that imatinib has an adverse effect on transplant-related morbidity or mortality (TMR). In addition, donor availability has benefitted from results showing equivalence of sibling and matched unrelated donors in terms of remission duration, non-relapse mortality and overall survival (OS).[1, 2] Several studies have shown improved post-transplant outcome of patients previously receiving imatinib-based treatment when compared with historic control groups, which have been dealt with in the previous chapter. As a consequence, most ALL study groups currently consider imatinib-based treatment, followed by matched related or unrelated allogeneic SCT (allo-SCT) in CR1, to be the gold standard of first-line therapy for Ph+ ALL. [3], Imatinib-based treatment not followed by SCT has been suggested to achieve OS and Disease Free Survival (DFS) similar to that obtained after SCT in one study, [4] and the results of MDACC study showed only a trend towards better OS in transplant‐ ed patients. [5] It still needs to be determined whether therapy based on second genera‐ tion TKI may be equivalent or superior to BMT in a subset of patients, particularly those

> © 2013 Milone and Alicia; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

> © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

and reproduction in any medium, provided the original work is properly cited.

**Positive Acute Lymphoblastic Leukemia (Ph+ ALL)**

Jorge Milone and Enrico Alicia

http://dx.doi.org/10.5772/55523

**1. Introduction**

at high risk of TRM

Additional information is available at the end of the chapter
