**9. Treatment of HLH and AAHS/MAS**

Early diagnosis and the prompt introduction of adequate therapy to produce a rapid response are crucial for a positive outcome in HLH. The treatment of any HLH type should focus on: (1) suppression of the hyperinflammatory state by destruction of activated CD8+ T lymphocytes and macrophages, and (2) treatment of any existing triggers (Gupta & Weitzman, 2010; Henter et al., 2007). In cases of FHL, an additional aim is the correction of the underlying immune defect (Filipovich, 2009; Henter et al., 2007; Janka, 2009). HLH treatment categories include: (1) proapoptotic chemotherapy with etoposide (100–150 mg/m²/dose i.v.), and (2) immunosuppressive drugs, targeting the hyperactivated macrophages (e.g., etoposide, corticosteroids, intravenous immunoglobulin), and T lymphocytes (e.g., corticosteroids, cyclosporine A [CyA]) (Henter et al., 2007). In 1994 the first prospective international treatment protocol (HLH-94) was introduced (Henetr et al., 1997). The experience from the HLH-94 protocol (including etoposide and dexamethasone [DXM]) and other studies have led to the development of a new treatment protocol, HLH-2004 (including etoposide, DXM, CyA) (Henter et al., 2007). However, immunochemotherapy (i.e., HLH-94 and HLH-2004 protocols) is only temporarily effective in the control of FHL, and the outcome is uniformly fatal unless the patient undergoes allogeneic stem cell transplantation (alloSCT) (Jordan & Filipovich, 2008; Henter et al., 2007). Last but not least, since patients with HLH represent a unique population with high morbidity/mortality and disease-specific complications, consideration should be given to referring these patients to centers with significant experience in the treatment and care of HLH.

#### **9.1 Immunochemotherapy**

Initially mild cases of HLH can deteriorate rapidly within a short period of time. Therefore, prompt administration of effective HLH therapy may prevent development of the fullblown syndrome. So far, treatment of AAHS/MAS is not standardized and remains highly variable across clinical centers (Deane et al., 2010). Nevertheless, a frontline treatment of AAHS/MAS (particularly of milder grades) usually involves corticosteroids with or without

FHL in 1999, it is expected that many new mutations in the known genes will be identified,

Viruses, non-steroidal anti-inflammatory drugs, methotrexate, gold salts, and even TNF-α inhibitors have been reported as triggers for AAHS/MAS (Gupta & Weitzman, 2010). Interestingly, distinctions between genetically determined and acquired HLH become increasingly blurred as brand new genetic causes are identified, and patients who develop HLH beyond early childhood or in the contexts of EBV infection or autoimmune disease are being found to share some of the same genetic etiologies (Arceci, 2008; Hazen et al., 2008; Nagafuji et al., 2007; Zhang et al., 2008). Patients who develop sHLH may also have a genetic predisposition, but the molecular basis of the defects in sHLH has yet to be discovered (Arceci, 2008). This supposition has recently been strengthened by recent studies showing decreased NK cell function or reduced perforin expression in children with sJIA complicated by MAS, similarly to patients with FHL (Grom et al., 2003; Wulffraat et al., 2003). Of note, mutations in *UNC13D* gene, mutated in FHL type 3, were also described in

Early diagnosis and the prompt introduction of adequate therapy to produce a rapid response are crucial for a positive outcome in HLH. The treatment of any HLH type should focus on: (1) suppression of the hyperinflammatory state by destruction of activated CD8+ T lymphocytes and macrophages, and (2) treatment of any existing triggers (Gupta & Weitzman, 2010; Henter et al., 2007). In cases of FHL, an additional aim is the correction of the underlying immune defect (Filipovich, 2009; Henter et al., 2007; Janka, 2009). HLH treatment categories include: (1) proapoptotic chemotherapy with etoposide (100–150 mg/m²/dose i.v.), and (2) immunosuppressive drugs, targeting the hyperactivated macrophages (e.g., etoposide, corticosteroids, intravenous immunoglobulin), and T lymphocytes (e.g., corticosteroids, cyclosporine A [CyA]) (Henter et al., 2007). In 1994 the first prospective international treatment protocol (HLH-94) was introduced (Henetr et al., 1997). The experience from the HLH-94 protocol (including etoposide and dexamethasone [DXM]) and other studies have led to the development of a new treatment protocol, HLH-2004 (including etoposide, DXM, CyA) (Henter et al., 2007). However, immunochemotherapy (i.e., HLH-94 and HLH-2004 protocols) is only temporarily effective in the control of FHL, and the outcome is uniformly fatal unless the patient undergoes allogeneic stem cell transplantation (alloSCT) (Jordan & Filipovich, 2008; Henter et al., 2007). Last but not least, since patients with HLH represent a unique population with high morbidity/mortality and disease-specific complications, consideration should be given to referring these patients to centers with significant experience in the treatment and care of

Initially mild cases of HLH can deteriorate rapidly within a short period of time. Therefore, prompt administration of effective HLH therapy may prevent development of the fullblown syndrome. So far, treatment of AAHS/MAS is not standardized and remains highly variable across clinical centers (Deane et al., 2010). Nevertheless, a frontline treatment of AAHS/MAS (particularly of milder grades) usually involves corticosteroids with or without

as well as some novel gene mutations (Gupta & Weitzman, 2010).

patients with sJIA (Hazen et al., 2008; Zhang et al., 2008).

**9. Treatment of HLH and AAHS/MAS** 

HLH.

**9.1 Immunochemotherapy** 

intravenous immunoglobulin (IVIG), which may be sufficient to control hyperinflammation (Janka, 2009). In order to achieve rapid reversal of the coagulation abnormalities and cytopenias, most clinicians prefer starting with intraveneous methylprednisolone pulse therapy (30 mg/kg for 3 consecutive days) followed by 2 to 3 mg/kg/day divided by 4 doses (Filipovich et al., 2010). After improvement of the complete blood count and resolution of the coagulopathy, steroids are tapered slowly to avoid relapses of MAS (Janka, 2009; Filipovich et al., 2010). High-dose corticosteroids alone have been reported to induce remission in approximately half of MAS patients (Sawhney et al., 2001 Stephan et al., 2001). Administration of IVIG might be effective in AAHS/MAS. High dose IVIG infusions are

immunosuppressive, in part engaging Fc-receptors, which can play an important role in same patients with autoimmune/autoinflammatory diseases (Arceci, 2008; Kumakura et al., 2004). IVIG may also provide an anti-pathogen effect, which is particularly important if MAS is triggered by a viral infection.

Even when treatment is introduced in a timely manner, MAS can be fatal and deaths have been reported among patients treated with massive doses of steroids (Filipovich et al., 2010). However, corticosteroid resistant non-responders may benefit from second-line therapies, such as CyA or etoposide. Parenteral administration of CyA has been shown to be effective in patients with corticosteroid-resistant MAS (Mouy et al., 1996; Ravelli et al., 1996). Of note, in author's experience, some patients with MAS have not responded until etoposide was added to the HLH therapy. The similar conclusion has recently been postulated by other authors (Gupta & Weitzman, 2010). Thus, if there is no response to the aforementioned drugs (corticosteroids, IVIG, CyA), use of the HLH-2004 protocol including etoposide is recommended (Table 9). In summary, patients with suspected AAHS/MAS could be started on therapy without etoposide, as long as treatment adjustments are made rapidly in refractory cases (Gupta & Weitzman, 2010).

The utility of biological response modifiers in MAS treatment remains unclear, and at the present there is no consensus on recommendations in respect to this group of drugs. The use of TNF-α inhibitors (etanercept, infliximab) in MAS has produced conflicting results, being the effective therapy in some patients (Makay et al., 2008; Sellmer et al., 2011), while triggering MAS in others (Sandhu et al., 2007). Biological agents that neutralize IL-1 (anakinra) and IL-6 (tocilizumab) have been reported to be effective in occasional MAS patients (Filipovich et al., 2010; Kelly & Ramanan, 2008), but the clinical experience is as yet limited. In the case of patients with a form of sHLH other than AAHS/MAS, which proved refractory to frontline HLH therapy, anecdotal reports on the beneficial use of plasma exchange, hemofiltration, antithrombin III, anti-CD52 antibodies (alemtuzumab), and anti-CD25 antibodies (daclizumab) have been published previously, but the role of these therapies is not yet validated for any type of HLH (Gupta & Weitzman, 2010). Lastly, if MAS is driven by EBV infection, monoclonal anti-CD20 antibodies (rituximab) which deplete B lymphocytes, the main type of cells harboring EBV virus, should be used (Balamuth et al., 2007).

#### **9.2 Stem cell transplantation**

The first successful allogeneic bone marrow transplantation in a case of HLH was reported in 1986 (Fischer et al., 1986). Since then, information regarding the role of alloSCT in the treatment of HLH has mostly concerned FHL (Janka, 2009; Marsh et al., 2010). In FHL, alloSCT is the only available curative treatment option with the reported 5-year overall

Autoimmune-Associated Hemophagocytic Syndrome/Macrophage Activation Syndrome 97

survival rate of 50–70% with myeloablative conditioning (MAC) (Baker et al., 1997; Cesaro et al., 2008; Dürken et al., 1999; Horne et al., 2005; Imashuku et al., 1999; Jabado et al., 1997; Ouachèe-Chardin et al., 2006), and 75–92% with reduced-intensity conditioning (RIC)

So far, alloSCT has been performed only occasionally in cases of acquired HLH and its role in the treatment of sHLH is not yet established. Sporadic case reports have previously been published on refractory EBV-HLH successfully treated by means of alloSCT (Minegishi et al., 2001; Sovinz et al., 2010; Toubo et al., 2004). A recent Japanese survey revealed a curative effect of alloSCT on sHLH in 7 out of 11 patients (64%) with refractory EBV-HLH (Ogha et al., 2010). Similarly, Yoon et al. reported that alloSCT could be a curative treatment not only for FHL, but also for relapsed/refractory sHLH (Yoon et al., 2010). Anecdotal reports have also shown the efficacy of alloSCT in M-HLH therapy (Chang et al., 2009; Goi et al., 1999;

No concerted effort to apply alloSCT for the definitive treatment of MAS has yet been made. Given the high mortality associated with the current management of AAHS/MAS, the option of alloSCT using less intensive conditioning protocols, is reasonable to consider, especially in cases of severe or recurrent MAS episodes (Filipovich et al., 2010). Of note, sometimes fatal MAS was observed as a complication of prolonged T lymphocyte immunodeficiency in early trials of autologous stem cell transplantation for severe progressive systemic or polyarticular juvenile idiopathic arthritis (Filipovich et al., 2010). These observations suggested a failure to control the underlying disease given the patient's

Autoimmune-associated hemophagocytic syndrome/macrophage activation syndrome is a life-threatening hyperinflammatory syndrome which remains a major cause of morbidity and mortality in patients with autoimmune/autoinflammatory diseases. Awareness of AAHS/MAS, its symptoms and diagnostic criteria should be made mandatory among all physicians, especially those providing care to patients with autoimmune/autoinflammatory diseases. There are no validated diagnostic criteria making early MAS diagnosis difficult in part owing to strong similarities between MAS and sepsis. The treatment of MAS remains highly variable across clinical centers. Nevertheless, the frontline treatment of AAHS/MAS usually involves corticosteroids with or without intravenous immunoglobulin. In some patients with corticosteroid-refractory MAS, administration of cyclosporine A circumvents refractoriness. If there is no response to the aforementioned treatments a use of etoposide is recommended. The progress in understanding the pathophysiology behind MAS and identification of the pathways associated with the early stages of this syndrome bring hope to the idea of developing

This work was supported by ALF resources (the agreement on clinical research between the Stockholm County Council and Karolinska Institutet). The authors thank Mr. J. Hubert and

genetically predisposed hematopoietic stem cells (Bleesing et al., 2007).

new biomarkers and treatments for clinical practice.

(Cooper et al., 2006; Marsh et al., 2010).

Kelly et al., 2011; Machaczka et al., 2011b).

**10. Conclusions** 

**11. Acknowledgments** 

Mr. F. Kasina for linguistic assistance.


\* – etoposide dose recommendations for adults are not validated proposal, but based on clinical experience (personal communication with Jan-Inge Henter)

HLH - hemophagocytic lymphohistiocytosis; CSF – cerebrospinal fluid; CyA – cyclosporine A; IVIG intravenous immunoglobulin; PPI – proton pump inhibitor.

Table 9. The HLH-2004 immunochemotherapy protocol for management of hemophagocytic lymphohistiocytosis

survival rate of 50–70% with myeloablative conditioning (MAC) (Baker et al., 1997; Cesaro et al., 2008; Dürken et al., 1999; Horne et al., 2005; Imashuku et al., 1999; Jabado et al., 1997; Ouachèe-Chardin et al., 2006), and 75–92% with reduced-intensity conditioning (RIC) (Cooper et al., 2006; Marsh et al., 2010).

So far, alloSCT has been performed only occasionally in cases of acquired HLH and its role in the treatment of sHLH is not yet established. Sporadic case reports have previously been published on refractory EBV-HLH successfully treated by means of alloSCT (Minegishi et al., 2001; Sovinz et al., 2010; Toubo et al., 2004). A recent Japanese survey revealed a curative effect of alloSCT on sHLH in 7 out of 11 patients (64%) with refractory EBV-HLH (Ogha et al., 2010). Similarly, Yoon et al. reported that alloSCT could be a curative treatment not only for FHL, but also for relapsed/refractory sHLH (Yoon et al., 2010). Anecdotal reports have also shown the efficacy of alloSCT in M-HLH therapy (Chang et al., 2009; Goi et al., 1999; Kelly et al., 2011; Machaczka et al., 2011b).

No concerted effort to apply alloSCT for the definitive treatment of MAS has yet been made. Given the high mortality associated with the current management of AAHS/MAS, the option of alloSCT using less intensive conditioning protocols, is reasonable to consider, especially in cases of severe or recurrent MAS episodes (Filipovich et al., 2010). Of note, sometimes fatal MAS was observed as a complication of prolonged T lymphocyte immunodeficiency in early trials of autologous stem cell transplantation for severe progressive systemic or polyarticular juvenile idiopathic arthritis (Filipovich et al., 2010). These observations suggested a failure to control the underlying disease given the patient's genetically predisposed hematopoietic stem cells (Bleesing et al., 2007).
