**Table 2.**

*Prognosis in B-ALL.*

*Advances in Hematologic Malignancies*

*3.4.1 Cytogenetic/genetic risk*

males overall.

phase of treatment and the achievement of remission at the end of induction are predictors of relapse risk and have prognostic importance. Gender has also been recognized as a prognostic factor, with females having a better outcome than

Cytogenetic analyses have demonstrated that chromosomal aberrations (insertions, deletions, translocations, and inversions) and numerical alterations (hyperdiploid, pseudodiploid, and hypodiploid) are hallmarks of ALL [106]. The prevalence of genetic subtypes differs with age and is of prognostic relevance. Approximately half of pediatric leukemia cases involve aneuploidy (with changes in chromosome number), including high hyperdiploidy (50–67 chromosomes) or hypodiploidy (44 chromosomes or fewer) [107]. The chromosome most frequently gained in patients with high hyperdiploidy is 21 (>90% cases with trisomy or tetrasomy of chromosome 21) [108]. It is thought that the duplication of specific chromosomes contributes to leukemogenesis, making high hyperdiploidy a stronger prognostic factor than hypodiploidy. Hypodiploidy has been associated with dismal prognosis in all observed cases of ALL. Near-haploid (24–31 chromosomes) and low-hypodiploid (32–39 chromosomes) ALLs exhibit activation of Ras- and PI3Ksignaling pathways, suggesting that these pathways may be a target for therapy in aggressive hypodiploid ALLs [109]. Studies in the pediatric population have identified genetic syndromes that are connected to the predisposition in a minority of cases of ALL, such as Down syndrome, Fanconi anemia, Bloom syndrome, ataxia

telangiectasia, and Nijmegen breakdown syndrome [89, 110, 111].

(BCR) and ABL proto-oncogene 1 (ABL1) [114].

Characteristic translocations include erythroblast transformation-specific (ETS) variant 6–Runt-related transcription factor 1 (ETV6-RUNX1), the most common translocation (15–25% of pediatric ALL patients) caused by t(12;21)(p13;q22). The prognosis of ALL with ETV6-RUNX1 is excellent [112]. A second common translocation in pediatric ALL is transcription factor 3-PBX homeobox 1 (TCF3- PBX1), which is caused by t(1;19)(q23;p13) and is observed in 5–10% of ALL cases. Previously, patients with this translocation were considered to have poor prognosis, but a recently improved treatment has resulted in better outcomes [113]. A small percentage of ALL patients (3–5%) exhibit the reciprocal translocation t(9;22) (q34;q11), also referred to as the "Philadelphia (Ph) chromosome." The Ph chromosome is largely prominent in patients suffering from chronic myeloid leukemia (CML) and is molecularly characterized by the creation of a non-receptor tyrosine kinase gene (BCR-ABL1) via the fusion of RhoGEF and GTPase-activating protein

The prevalence of t(9;22) in adult ALL can range from 15 to 50% and increases with age [115]. Ph chromosome positivity has been widely considered to be a factor for poor prognosis. The development of tyrosine kinase inhibitors (TKI), which directly target BCR-ABL1, has shown to significantly improve the treatment strategy for Ph-ALL. Rearrangement of the mixed-lineage leukemia 1 gene (MML1), also known as KMT2A (lysine [K]-specific methyltransferase 2A), on chromosome 11q23 is found in a unique group of acute leukemias and predicts a very poor

More recently, a variant with a similar gene expression profile to Ph-positive ALL, but without the BCR-ABL1 rearrangement, has been identified. This so-called Ph-like ALL, or BCR-ABL1-like ALL, has been associated with poor response to induction chemotherapy, elevated minimal residual disease, and poor survival [117]. The prevalence of Ph-like ALL is common among all ages, ranging from 10 to 15% in children to over 25% in young adults [118]. Patients with Ph-like ALL

**82**

outcome [116].

T-ALL is characterized by numerous transcriptional, signaling, and epigenetic factors. Activating mutations in NOTCH1 can be found in the majority of T-ALL cases and predict a favorable prognosis [124]. Deletions of the CDKN2A locus encoding the P16/INK4A and P19/ARF tumor suppressors, responsible for control of cell cycle progression and P53 regulation, respectively, are present in about 70% of T-ALLs [125]. Gene expression profiling has identified major categories of T-ALL associated with gene expression during thymocyte development. Cytokine receptor RAS signaling genes, which include FLT3, have been found to be activated by mutation in early T-cell precursor T-ALL (ETP T-ALL). In addition, alterations in genes which disturb hematopoietic development, such as GATA 3, ETV6, and RUNX1, have been observed. Lastly, mutations in histonemodifying genes (EZH2, SUZ12, and EED) are also a consequence of ETP T-ALL. ETP T-ALL has been associated with poor prognosis [126]. Early cortical thymocyte leukemias are primarily associated with translocations resulting in aberrant expression of TLX1, TLX3, and related homeobox transcription factor oncogenes; these exhibit a characteristically favorable outcome [125, 127]. Late cortical leukemias occur further down in the pattern of gene expression programming related to T-cell development, overexpressing the transcription factor oncogene TAL1 with either LMO1 or LMO2 and PTEN. These are associated with poor prognosis [125, 127].

#### **3.5 Therapy**

Typical chemotherapy consists of induction, consolidation, and long-term maintenance, with CNS prophylaxis given at intervals throughout therapy. The goal of induction therapy is to achieve complete remission and to restore a normal blood cell count. Predominantly 85–90% of patients achieve complete remission after 4–6 weeks of this regimen [128]. Several chemotherapeutic agents are currently used in the treatment of CLL, including amascrine, asparaginase, cyclophosphamide, cytarabine, daunorubicin, dexamethasone, and methotrexate. Each utilizes slightly differing mechanisms of action; in the general sense however, these molecules affect the growth and division of cancer cells by inducing DNA damage [129]. Multi-agent cytotoxic chemotherapy has had great success in pediatric age groups [130]. Pediatric-inspired treatment protocols have also shown superior outcomes in young adults [104], but the same success has not been reproduced in adults despite regime modifications. Traditional adult treatment protocols include intensive myelosuppressive agents as well as allogeneic hematopoietic stem cell transplant (allo-SCT) in first remission [104]. After achieving complete response, treatment options include consolidation and maintenance chemotherapy or allo-SCT for eligible patients [131]. For high-risk patients (Ph-positive ALL, elevated WBC count, CNS disease, high-risk gene rearrangements, or hypodiploidy) and patients with relapsed/refractory disease, allo-SCT has long been considered the standard of care. However, the advent of TKIs marked a turning point in the treatment of some high-risk subtypes such as Ph-ALL and Ph-like ALL. After induction therapy, subsequent consolidation therapy begins to eradicate residual leukemic cells. Consolidation varies in different protocols but generally utilizes similar agents for induction (various combinations of cytotoxic agents and high dose of escalating methotrexate) and at times includes intrathecal chemotherapy and cranial radiation for CNS prophylaxis [132]. Maintenance therapy typically lasts 1–2 years. Daily 6-mercaptopurine (6-MP) and weekly MTX are a standard combination, and some maintenance therapies are enhanced with vincristine and steroids [80].

**85**

treatment for T-ALL.

**4. Protein markers of CLL and ALL as a new therapeutic targets**

New specific protein markers connected with CLL and ALL which have been discovered in the last 10–15 years represent novel potential targets for highly personalized treatments of leukemia. These proteins, associated with different cellular signaling events, mostly include surface receptors/transmembrane proteins—CD5, CD19, CD20, CD22, CD23, CD52, and many others [9, 11, 31, 33, 38]—where protein phosphorylation may play an important role in protein

*New Protein Markers of Chronic Lymphocytic and Acute Lymphocytic Leukemia*

A better understanding of the molecular landscape of ALL and advances in the field of monoclonal antibody therapy have resulted in the development of several new agents, especially in the treatment of adolescent and young adults (AYA) and adult patients. Targeted delivery of monoclonal antibodies based on leukemic cellsurface receptor recognition improves efficacy and minimizes off-target toxicity. The antigens CD19, CD20, CD22, and CD52 are the most common antigens to which monoclonal antibodies in B-cell ALL have been directed. Rituximab is a non-conjugated monoclonal antibody designed to target a single antigen on the tumor cell surface. The combination of rituximab with chemotherapy in the frontline treatment of CD20-positive B-ALL has been shown to increase CR duration, lower relapse rates, and improve event-free survival [133]. A new generation of monoclonal antibodies exists which is characterized by the antibody being conjugated to drug or toxins with the purpose of enhancing the efficiency of cancer cell killing. For example, inotuzumab ozogamicin (IO) is a monoclonal antibody against CD22 linked to the cytotoxic agent, calicheamicin. The use of IO alone, and in combination with chemotherapy, has shown promise in relapsed and refractory B-cell ALL [134]. Other modifications to antibody constructs can also augment immunogenic reactions against leukemia. Blinatumomab is the first approved drug in the BiTE class, a bispecific T-cell receptor engager, which has both a monoclonal antibody against CD19 and an anti-CD3 T cell-binding domain. Monotherapy in relapsed and refractory B-cell ALL has resulted in prolonged relapse-free survival [135]. The effectiveness and safety of several newer monoclonal antibodies including ofatumumab [136], obinutuzumab, epratuzumab [137], and moxetumomab pasudotox [138] as single agents or in combination with a chemotherapeutic are currently under investigation. Chimeric antigen receptor (CAR) therapy has shown remarkable efficacy in B-cell ALL. CAR combines both antigen-binding and T-cell activating functions into a single receptor. CAR-modified T cells involve a mechanism in which a patient's own T cells are genetically programmed to recognize leukemic cells, inducing an antileukemic immune response. Complete remission rates as high as 90% have been reported in children and adults with relapsed and refractory ALL posttreatment with CARmodified T cells targeting the B cell-specific antigen CD19 [139]. Treatment of the high-risk Ph-like ALL has significantly improved with the identification of genetic alterations which deregulate cytokine receptor and tyrosine kinase signaling, both common features of this subtype of ALL. Tyrosine kinase inhibitors (TKIs) such as imatinib, dasatinib, nilotinib, and ponatinib, NOTCH1 and DOT1L pathway inhibitors, and JAK inhibitors have become novel agents for Ph-like ALL therapy. In addition, 50% of Ph-like ALLs show activation of phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) and mammalian target of rapamycin (mTOR) pathways and could therefore present potential targets for mTOR inhibitors [140]. Inhibition of the PI3K/AKT/mTOR pathways may be an effective

*DOI: http://dx.doi.org/10.5772/intechopen.85449*

#### *New Protein Markers of Chronic Lymphocytic and Acute Lymphocytic Leukemia DOI: http://dx.doi.org/10.5772/intechopen.85449*

A better understanding of the molecular landscape of ALL and advances in the field of monoclonal antibody therapy have resulted in the development of several new agents, especially in the treatment of adolescent and young adults (AYA) and adult patients. Targeted delivery of monoclonal antibodies based on leukemic cellsurface receptor recognition improves efficacy and minimizes off-target toxicity. The antigens CD19, CD20, CD22, and CD52 are the most common antigens to which monoclonal antibodies in B-cell ALL have been directed. Rituximab is a non-conjugated monoclonal antibody designed to target a single antigen on the tumor cell surface. The combination of rituximab with chemotherapy in the frontline treatment of CD20-positive B-ALL has been shown to increase CR duration, lower relapse rates, and improve event-free survival [133]. A new generation of monoclonal antibodies exists which is characterized by the antibody being conjugated to drug or toxins with the purpose of enhancing the efficiency of cancer cell killing. For example, inotuzumab ozogamicin (IO) is a monoclonal antibody against CD22 linked to the cytotoxic agent, calicheamicin. The use of IO alone, and in combination with chemotherapy, has shown promise in relapsed and refractory B-cell ALL [134]. Other modifications to antibody constructs can also augment immunogenic reactions against leukemia. Blinatumomab is the first approved drug in the BiTE class, a bispecific T-cell receptor engager, which has both a monoclonal antibody against CD19 and an anti-CD3 T cell-binding domain. Monotherapy in relapsed and refractory B-cell ALL has resulted in prolonged relapse-free survival [135]. The effectiveness and safety of several newer monoclonal antibodies including ofatumumab [136], obinutuzumab, epratuzumab [137], and moxetumomab pasudotox [138] as single agents or in combination with a chemotherapeutic are currently under investigation. Chimeric antigen receptor (CAR) therapy has shown remarkable efficacy in B-cell ALL. CAR combines both antigen-binding and T-cell activating functions into a single receptor. CAR-modified T cells involve a mechanism in which a patient's own T cells are genetically programmed to recognize leukemic cells, inducing an antileukemic immune response. Complete remission rates as high as 90% have been reported in children and adults with relapsed and refractory ALL posttreatment with CARmodified T cells targeting the B cell-specific antigen CD19 [139]. Treatment of the high-risk Ph-like ALL has significantly improved with the identification of genetic alterations which deregulate cytokine receptor and tyrosine kinase signaling, both common features of this subtype of ALL. Tyrosine kinase inhibitors (TKIs) such as imatinib, dasatinib, nilotinib, and ponatinib, NOTCH1 and DOT1L pathway inhibitors, and JAK inhibitors have become novel agents for Ph-like ALL therapy. In addition, 50% of Ph-like ALLs show activation of phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) and mammalian target of rapamycin (mTOR) pathways and could therefore present potential targets for mTOR inhibitors [140]. Inhibition of the PI3K/AKT/mTOR pathways may be an effective treatment for T-ALL.

### **4. Protein markers of CLL and ALL as a new therapeutic targets**

New specific protein markers connected with CLL and ALL which have been discovered in the last 10–15 years represent novel potential targets for highly personalized treatments of leukemia. These proteins, associated with different cellular signaling events, mostly include surface receptors/transmembrane proteins—CD5, CD19, CD20, CD22, CD23, CD52, and many others [9, 11, 31, 33, 38]—where protein phosphorylation may play an important role in protein

*Advances in Hematologic Malignancies*

poor prognosis [125, 127].

**3.5 Therapy**

T-ALL is characterized by numerous transcriptional, signaling, and epigenetic factors. Activating mutations in NOTCH1 can be found in the majority of T-ALL cases and predict a favorable prognosis [124]. Deletions of the CDKN2A locus encoding the P16/INK4A and P19/ARF tumor suppressors, responsible for control of cell cycle progression and P53 regulation, respectively, are present in about 70% of T-ALLs [125]. Gene expression profiling has identified major categories of T-ALL associated with gene expression during thymocyte development. Cytokine receptor RAS signaling genes, which include FLT3, have been found to be activated by mutation in early T-cell precursor T-ALL (ETP T-ALL). In addition, alterations in genes which disturb hematopoietic development, such as GATA 3, ETV6, and RUNX1, have been observed. Lastly, mutations in histonemodifying genes (EZH2, SUZ12, and EED) are also a consequence of ETP T-ALL. ETP T-ALL has been associated with poor prognosis [126]. Early cortical thymocyte leukemias are primarily associated with translocations resulting in aberrant expression of TLX1, TLX3, and related homeobox transcription factor oncogenes; these exhibit a characteristically favorable outcome [125, 127]. Late cortical leukemias occur further down in the pattern of gene expression programming related to T-cell development, overexpressing the transcription factor oncogene TAL1 with either LMO1 or LMO2 and PTEN. These are associated with

Typical chemotherapy consists of induction, consolidation, and long-term maintenance, with CNS prophylaxis given at intervals throughout therapy. The goal of induction therapy is to achieve complete remission and to restore a normal blood cell count. Predominantly 85–90% of patients achieve complete remission after 4–6 weeks of this regimen [128]. Several chemotherapeutic agents are currently used in the treatment of CLL, including amascrine, asparaginase, cyclophosphamide, cytarabine, daunorubicin, dexamethasone, and methotrexate. Each utilizes slightly differing mechanisms of action; in the general sense however, these molecules affect the growth and division of cancer cells by inducing DNA damage [129]. Multi-agent cytotoxic chemotherapy has had great success in pediatric age groups [130]. Pediatric-inspired treatment protocols have also shown superior outcomes in young adults [104], but the same success has not been reproduced in adults despite regime modifications. Traditional adult treatment protocols include intensive myelosuppressive agents as well as allogeneic hematopoietic stem cell transplant (allo-SCT) in first remission [104]. After achieving complete response, treatment options include consolidation and maintenance chemotherapy or allo-SCT for eligible patients [131]. For high-risk patients (Ph-positive ALL, elevated WBC count, CNS disease, high-risk gene rearrangements, or hypodiploidy) and patients with relapsed/refractory disease, allo-SCT has long been considered the standard of care. However, the advent of TKIs marked a turning point in the treatment of some high-risk subtypes such as Ph-ALL and Ph-like ALL. After induction therapy, subsequent consolidation therapy begins to eradicate residual leukemic cells. Consolidation varies in different protocols but generally utilizes similar agents for induction (various combinations of cytotoxic agents and high dose of escalating methotrexate) and at times includes intrathecal chemotherapy and cranial radiation for CNS prophylaxis [132]. Maintenance therapy typically lasts 1–2 years. Daily 6-mercaptopurine (6-MP) and weekly MTX are a standard combination, and some maintenance therapies are enhanced with vincristine and

**84**

steroids [80].

activity regulation connected to the progression of disease and regulation of pathological events [12–14]. Focusing on such specific modifications presents key opportunities to further facilitate efficient and precise drug strategy design [55–58]. Inhibition of protein kinases associated with key phosphorylations has been an intense research topic in the last decade [67–69, 72, 73, 75]. Significant progress in protein mass spectrometry techniques, specific antibody design and development, parallel studies of genes, epigenetic proteome, and related proteins including their disease-related modifications altogether open a new horizon for a more sensitive and personalized approach to the diagnosis and treatment methods of CLL and ALL. The combination of such approaches should further facilitate the development of more efficient drugs and approaches which more specifically target the key signaling events concerning the onset and progression of the disease. Based on the fact that proteome maps are unique to each individual, there is an urgent need for personalized diagnostics and a personalized molecular treatment approach. Using the information from the proteins associated with the CLL and ALL, and the misregulation of signaling pathways in associated cell regulation events, the precise and detailed protein signaling outcome can form the base of potential success in the domain of efficient drug design and consequent molecular treatment, without the typical side effects of current conventional methods.
