Allogeneic stem cell transplantation after reduced-intensity conditioning in patients with myelofibrosis: a prospective, multicenter study of the Chronic Leukemia Working Party of the European Group for Blood and Marrow Transplantation

Efficacy of ruxolitinib for myelofibrosis

INTRODUCTION

The discovery of the activating JAK2 V617F mutation in patients with myelofibrosis (MF) led to the development of JAK2 inhibitors. The first such inhibitor to enter clinical trials was ruxolitinib . This review summarizes preclinical and clinical data of ruxolitinib in MF.

AREAS COVERED

A literature search through Medline employing the terms 'ruxolitinib,' 'INCB018424' and 'myelofibrosis' was undertaken. The results from Phase I/II studies in patients with MF showed that ruxolitinib led to durable improvements in splenomegaly, and symptoms associated with MF. Two Phase III trials have compared ruxolitinib against placebo and best available therapy, and in both studies ruxolitinib demonstrated superior rates of spleen control and symptom improvement, and additional analysis demonstrated a survival benefit with ruxolitinib treatment. The main toxicities seen with ruxolitinib are cytopenias, which are managed with dose adjustments. Recent reports documented sporadic cases of immunosuppression-related infections. Ruxolitinib is the first drug ever approved for the therapy of patients with MF.

EXPERT OPINION

Understanding the factors that predict the rate and duration of response to ruxolitinib would improve our ability to manage patients treated with this medication. Clinical trials combining ruxolitinib with novel compounds that are also active in MF will further improve therapy for this disease.

The new landscape of therapy for myelofibrosis

The landscape of therapy for myelofibrosis (MF) is evolving at a pace not previously seen for this clonal myeloproliferative neoplasm. The discovery of the JAK2 V617F mutation in 2005 has led to the rapid development of therapy specifically developed for afflicted MF patients. Indeed, the successful phase III studies of ruxolitinib demonstrating improved symptomatic burden, splenomegaly and survival led to the first approved myelofibrosis drug in the United States and Europe. Multiple additional JAK2 inhibitors are currently in or nearing phase III testing, including SAR302503 (fedratinib), SB1518 (pacritinib) and CYT387 (momelotinib), seeking to offer incremental benefits to ruxolitinib in regards to cytopenias or other disease features. In parallel, phase III testing of pomalidomide is ongoing, with the goal of solidifying the role of immunomodulatory therapy in MF-associated anemia. Multiple single agents strategies are ongoing with histone deacetylase inhibitors, hedgehog inhibitors and hypomethylation agents. Incremental advances are further sought, either in additive or synergistic fashion, from combination strategies of ruxolitinib with multiple different approaches ranging from allogeneic stem cell transplant to current therapies mitigating anemia and further impacting the bone marrow microenvironment or histology. Transitioning from a pre-2011 era devoid of approved MF therapies to one of multiple agents that target not only disease course but symptomatic burden has indeed changed the platform from which MF providers are able to launch individualized treatment plans. In this article, we discuss the diagnostic and therapeutic milestones achieved through MF research and review the emerging pharmacologic agents on the treatment horizon.

Targeting hedgehog signaling in myelofibrosis and other hematologic malignancies

Treatment of myelofibrosis (MF), a BCR-ABL-negative myeloproliferative neoplasm, is challenging. The only current potentially curative option, allogeneic hematopoietic stem cell transplant, is recommended for few patients. The remaining patients are treated with palliative therapies to manage MF-related anemia and splenomegaly. Identification of a mutation in the Janus kinase 2 (JAK2) gene (JAK2 V617F) in more than half of all patients with MF has prompted the discovery and clinical development of inhibitors that target JAK2. Although treatment with JAK2 inhibitors has been shown to improve symptom response and quality of life in patients with MF, these drugs do not alter the underlying disease; therefore, novel therapies are needed. The hedgehog (Hh) signaling pathway has been shown to play a role in normal hematopoiesis and in the tumorigenesis of hematologic malignancies. Moreover, inhibitors of the Hh pathway have been shown to inhibit growth and self-renewal capacity in preclinical models of MF. In a mouse model of MF, combined inhibition of the Hh and JAK pathways reduced JAK2 mutant allele burden, reduced bone marrow fibrosis, and reduced white blood cell and platelet counts. Preliminary clinical data also suggest that inhibition of the Hh pathway, alone or in combination with JAK2 inhibition, may enable disease modification in patients with MF. Future studies, including one combining the Hh pathway inhibitor sonidegib and the JAK2 inhibitor ruxolitinib, are underway in patients with MF and will inform whether this combination approach can lead to true disease modification.

Allogeneic transplantation for myelofibrosis: for whom, when, and what are the true benefits?

PURPOSE OF REVIEW

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only potentially curative therapy for myelofibrosis. Despite improved outcomes, morbidity and mortality of HSCT remain high. Here we examine recent data on patient selection, timing, and outcomes of HSCT in myelofibrosis.

RECENT FINDINGS

While there is a general effort to restrict HSCT to transplant-eligible intermediate-2 and high-risk patients, this group has comparatively worse HSCT outcomes, largely driven by their high transplant-related mortality (TRM). When adjusted for age, reduced intensity conditioning (RIC) has shown superior outcomes compared with myeloablative conditioning (MAC), making RIC-HSCT a viable option for older patients. Emerging concepts include the use of ruxolitinib pretransplant, optimizing MAC to decrease toxicity, and use of posttransplant JAK2-mutant allele burden to guide prophylactic immunotherapy to prevent relapse. The recognition of prognostic significance of somatic mutations in the ASXL1, EZH2, SRSF2, and IDH1/2 genes, and the improved assessment of risk of leukemic transformation have added a new dimension to risk stratification.

SUMMARY

Improving our understanding of molecular genetics and leukemic transformation holds promise for more precise patient selection for HSCT. Although RIC-HSCT may reduce TRM, further studies are needed to optimize conditioning regimens and to define the optimal timing of HSCT.

Allogeneic hematopoietic stem cell transplantation in patients with polycythemia vera or essential thrombocythemia transformed to myelofibrosis or acute myeloid leukemia: a report from the MPN Subcommittee of the Chronic Malignancies Working Party of the European Group for Blood and Marrow Transplantation

The clinical course of polycythemia vera and essential thrombocythemia is potentially associated with long-term severe complications, such as evolution to myelofibrosis or acute myeloid leukemia. Allogeneic stem cell transplantation is currently the only potentially curative treatment for advanced polycythemia vera or essential thrombocythemia. We analyzed 250 consecutive patients with an initial diagnosis of polycythemia vera (n=120) or essential thrombocythemia (n=130), who underwent transplantation due to progression to myelofibrosis (n=193) or acute myeloid leukemia (n=57) and who were reported to the European Group for Blood and Marrow Transplantation registry between 1994 and 2010. Their median age was 56 years (range, 22-75) and in 52% of cases the interval between diagnosis and transplantation was 10 years or more. With a median follow-up from transplantation of 13 months, the 3-year overall survival rate and relapse incidence were 55% and 32%, respectively. In univariate analysis, the main parameters that negatively affected post-transplantation outcomes were older age (>55 years), a diagnosis at transplant of acute myeloid leukemia and the use of an unrelated donor. The overall 3-year cumulative incidence of non-relapse mortality was 28%, but was significantly higher in older patients than in younger ones (>55 years, 35% versus 20%, P=0.032), in those transplanted from an unrelated donor rather than a related donor (34% versus 18%, P=0.034) and in patients with a diagnosis of acute myeloid leukemia compared to myelofibrosis (29% versus 27%, P=0.045). This large retrospective study confirms that transplantation is potentially curative for patients with end-stage polycythemia vera/essential thrombocythemia progressing to myelofibrosis or acute myeloid leukemia. Relapse and non-relapse mortality remain unsolved problems for which innovative treatment approaches need to be assessed.

Reduced-intensity hematopoietic cell transplantation for patients with primary myelofibrosis: a cohort analysis from the center for international blood and marrow transplant research

We evaluated outcomes and associated prognostic factors in 233 patients undergoing allogeneic hematopoietic cell transplantation (HCT) for primary myelofibrosis (MF) using reduced-intensity conditioning (RIC). The median age at RIC HCT was 55 yr. Donors were a matched sibling donor (MSD) in 34% of RIC HCTs, an HLA well-matched unrelated donor (URD) in 45%, and a partially matched/mismatched URD in 21%. Risk stratification according to the Dynamic International Prognostic Scoring System (DIPSS) was 12% low, 49% intermediate-1, 37% intermediate-2, and 1% high. The probability of survival at 5 yr was 47% (95% confidence interval [CI], 40% to 53%). In a multivariate analysis, donor type was the sole independent factor associated with survival. Adjusted probabilities of survival at 5-yr were 56% (95% CI, 44% to 67%) for MSD, 48% (95% CI, 37% to 58%) for well-matched URD, and 34% (95% CI, 21% to 47%) for partially matched/mismatched URD (P = .002). The relative risk (RR) for NRM was 3.92 (P = .006) for well-matched URD and 9.37 (P < .0001) for partially matched/mismatched URD. Trends toward increased NRM (RR, 1.7; P = .07) and inferior survival (RR, 1.37; P = .10) were observed in DIPSS intermediate-2/high-risk patients compared with DIPSS low/intermediate-1 risk patients. Our data indicate that RIC HCT is a potentially curative option for patients with MF, and that donor type is the most important factor influencing survival in these patients.

Allogeneic hematopoietic cell transplantation for myelofibrosis in patients pretreated with the JAK1 and JAK2 inhibitor ruxolitinib

The Janus-activated kinase 1 (JAK1) and JAK2 inhibitor ruxolitinib is effective in decreasing symptomatic splenomegaly and myelofibrosis (MF)-related symptoms. However, allogeneic hematopoietic cell transplantation (HCT) remains the only curative option. We evaluated the impact of ruxolitinib on the outcome after HCT. A cohort of 14 patients (median age 58 years) received a subsequent graft from related (n=3) and unrelated (n=11) donors after a median exposure of 6.5 months to ruxolitinib. At HCT, MF risk for survival according to the International Prognostic Scoring System was intermediate-2 or high risk in 86% of patients. Under ruxolitinib, MF-related symptoms were ameliorated in 10 (71.4%) patients and the palpable spleen reduced by a median of 41% in 7 (64%) of 11 patients with splenomegaly. Engraftment occurred in 13 (93%) patients. Acute GvHD grade-III occurred in 2 (14%) patients. Median follow-up was 9 months. Survival, EFS and treatment-related mortality were 78.6, 64 and 7%, respectively. Through the anti-JAK-mediated reduction in both cytokines and splenomegaly as well as improvement in performance status, ruxolitinib might improve outcome after allogeneic HCT in patients with MF. The downregulation of inflammatory cytokines might have a beneficial impact on graft failure and acute GvHD.

VPS 45-associated primary infantile myelofibrosis--successful treatment with hematopoietic stem cell transplantation

PMF of infancy is a recently described autosomal recessive disorder presenting with severe bone marrow failure, accelerated neutrophil apoptosis, and significant platelet dysfunction, caused by a mutation in the VPS45 gene. In this study, we update our group of patients with PMF, highlighting different aspects of this disease, and evaluating the effectiveness of HSCT for the treatment of this disorder. Update of clinical data, hematological features, molecular studies, treatment and final outcome of four children diagnosed with VPS 45-associated PMF of infancy. The patients described had clinical and hematological findings consistent with MF. Molecular studies showed that all patients were homozygous for the Thr224Asn mutation in the VPS 45 gene. HSCT was carried out in three patients and was successful in two. VPS 45-associated MF is a novel primary immune deficiency that can be successfully corrected by HSCT if applied early in the course of disease using appropriate conditioning. The diagnosis of VPS 45-associated PMF should be considered in all children presenting with SCN with subsequent development of pancytopenia. Long-term follow-up of these patients is necessary to identify extra-hematological manifestations of VPS45 deficiency.

Treatment options for myelofibrosis and myeloproliferative neoplasia

SUMMARY Essential thrombocythemia, polycythemia vera and primary myelofibrosis belong to the Philadelphia chromosome negative (Ph-) myeloproliferative neoplasia (MPN) group of diseases. MPNs are clonal bone marrow stem cell disorders characterized by a proliferation of one or more of the myeloid, erythroid or megakaryocytic cell lines. The treatment of MPN patients should be carried out according to their risk stratification. In 2005 a mutation in the JAK2 gene was discovered that generated more insight into the pathogenetic working mechanism of MPNs. However, the treatment of MPN patients is still mainly only palliative, although progress is being made in reducing the symptoms for MPN patients. This review will give a general overview of the treatment of MPN patients.

Allogeneic transplantation for primary myelofibrosis with BM, peripheral blood or umbilical cord blood: an analysis of the JSHCT

To determine whether a difference in donor source affects the outcome of transplantation for patients with primary myelofibrosis (PMF), a retrospective study was conducted using the national registry data on patients who received first allogeneic hematopoietic cell transplantation (HCT) with related BM (n=19), related PBSCs (n=25), unrelated BM (n=28) or unrelated umbilical cord blood (UCB; n=11). The 5-year OS rates after related BM, related PBSC and unrelated BM transplantation were 63%, 43% and 41%, respectively, and the 2-year OS rate after UCB transplantation was 36%. On multivariate analysis, the donor source was not a significant factor for predicting the OS rate. Instead, performance status (PS) ⩾2 (vs PS 0–1) predicted a lower OS (P=0.044), and RBC transfusion ⩾20 times before transplantation (vs transfusion ⩽9 times) showed a trend toward a lower OS (P=0.053). No advantage of nonmyeloablative preconditioning regimens in terms of decreasing nonrelapse mortality or increasing OS was found. Allogeneic HCT, and even unrelated BM and UCB transplantation, provides a curative treatment for PMF patients.

Allogeneic stem cell transplantation for myelofibrosis with leukemic transformation: a study from the Myeloproliferative Neoplasm Subcommittee of the CMWP of the European Group for Blood and Marrow Transplantation

Transformed acute myeloid leukemia in myelofibrosis results in a median survival of less than 5 months. We identified 46 of 1048 myelofibrosis patients in the European Group for Blood and Marrow Transplantation registry who received allogeneic stem cell transplantation for acute leukemia evolving from myelofibrosis. The cumulative incidence of treatment-related mortality at 1 year was 28% (95% confidence interval, 14 to 42) and of relapse at 3 years was 47% (95% confidence interval, 31 to 63). The 3-year progression-free (PFS) and overall survival (OS) rates were 26% and 33%, respectively. The only significant factor for survival was complete remission versus no complete remission before transplantation (69% versus 22%, P = .008); however, complete remission was achieved only in 8 patients. Allogeneic stem cell transplantation can cure myelofibrosis patients transformed to leukemia.

Applications of human hematopoietic stem cells isolated and expanded from different tissues in regenerative medicine

Bone marrow transplantation is a well-established stem cell-based therapy for the management of malignant and nonmalignant hematological disorders. In addition to the bone marrow, therapeutic hematopoietic stem cells (HSCs) can also be obtained from umbilical cord blood and mobilized peripheral blood. Transplantation of HSCs isolated from these tissues can be carried out with or without prior enrichment of specific cell types. New methodologies have been developed for lineage-specific HSC expansion and their transplantation as a supplementary treatment to whole bone marrow transplantation. In this review we have described the current methodologies for isolating and processing HSCs from various tissues, and discussed strategies to generate sufficient and functional HSCs for clinical and preclinical applications by expansion ex vivo. The various disease conditions in which these cells could be used, and the methods for delivering the cells into patients, are also discussed.

Advances in myelofibrosis: a clinical case approach

Primary myelofibrosis is a member of the myeloproliferative neoplasms, a diverse group of bone marrow malignancies. Symptoms of myelofibrosis, particularly those associated with splenomegaly (abdominal distention and pain, early satiety, dyspnea, and diarrhea) and constitutional symptoms, represent a substantial burden to patients. Most patients eventually die from the disease, with a median survival ranging from approximately 5-7 years. Mutations in Janus kinase 2 (JAK2), a kinase that is essential for the normal development of erythrocytes, granulocytes, and platelets, notably the V617F mutation, have been identified in approximately 50% of patients with myelofibrosis. The approval of a JAK2 inhibitor in 2011 has improved the outlook of many patients with myelofibrosis and has changed the treatment landscape. This article focuses on some of the important issues in current myelofibrosis treatment management, including differentiation of myelofibrosis from essential thrombocythemia and polycythemia vera, up-dated data on the results of JAK2 inhibitor therapy, the role of epigenetic mechanisms in myelofibrosis pathogenesis, investigational therapies for myelofibrosis, and advances in hematopoietic stem cell transplant. Three myelofibrosis cases are included to underscore the issues in diagnosing and treating this complex disease.

Emerging therapies for the treatment of chronic Philadelphia chromosome-negative myeloproliferative neoplasm-associated myelofibrosis

INTRODUCTION

Chronic Philadelphia chromosome-negative myeloproliferative neoplasm-associated myelofibrosis significantly impacts afflicted patients with cytopenia, splenomegaly, debilitating constitutional symptoms and decreased survival. Approval of the first Janus kinase 2 (JAK2) inhibitor therapy, ruxolitinib, has improved splenomegaly, symptomatic burden, survival and perhaps fibrosis in some treated patients; however, other patients remain symptomatic and are in need of alternate therapeutic strategies.

AREAS COVERED

A review of recent literature via PubMed and meeting abstracts has revealed many studies investigating new treatment approaches for chronic Philadelphia chromosome-negative myeloproliferative neoplasms. Multiple additional JAK2 inhibitors (fedratinib, pacritinib and momelotinib) are well into single agent development, as well as multiple combination approaches with ruxolitinib. Efforts to combine JAK2 inhibition with agents to improve cytopenia, marrow fibrosis, additional pathway inhibitors and even allogeneic transplant are planned or ongoing. Additionally, Phase III trials of immunomodulation with pomalidomide are ongoing.

EXPERT OPINION

This article discusses investigational therapies for the treatment of Philadelphia chromosome-negative myeloproliferative neoplasms, particularly those in Phase II clinical trials, employing new JAK2 inhibitors, novel multi-agent therapeutic approaches and innovative new drug targets. Additionally, the future era of Philadelphia chromosome-negative myeloproliferative neoplasms is addressed with potentially expanded niches for JAK2 inhibition.

Revised response criteria for myelofibrosis: International Working Group-Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) and European LeukemiaNet (ELN) consensus report

The current document is a revision of the International Working Group-Myeloproliferative Neoplasms Research and Treatment (IWG-MRT) criteria for treatment response in myelofibrosis (MF) and represents a collaborative effort by the IWG-MRT and the European LeukemiaNet to objectively assess the value of new drugs in inducing morphologic remission or improvement in MF-associated symptomatic burden (MF-SB). Some of the changes in the current revision include stricter definitions of red cell transfusion dependency and independency and consideration of the Myeloproliferative Neoplasm Symptom Assessment Form as a tool to quantify meaningful changes in disease-related symptoms. Six response categories are listed: complete remission (CR) and partial remission signify treatment effects that are consistent with disease modification, whereas drug-induced improvements in MF-SB were annotated as clinical improvement, anemia response, spleen response, or symptoms response. Additional criteria are provided for progressive disease, stable disease, and relapse. The document also includes recommendations for assessing cytogenetic and molecular remissions, without mandating their inclusion for CR assignment.

Indications and outcomes of reduced-toxicity hematopoietic stem cell transplantation in adult patients with hematological malignancies

Hematopoietic stem cell transplantation (HCT) utilizing non-myeloablative (NMA) and reduced-intensity conditioning (RIC) regimens (collectively referred to as reduced-toxicity HCT, RT-HCT) has become a viable therapeutic option for patients with hematological malignancies who are ineligible for standard myeloablative conditioning transplantation (MA-HCT). RT-HCT has been shown to induce stable engraftment with low toxicity, and to produce similar overall and progression-free survival (PFS) when compared to MA-HCT in acute myeloid leukemia and myelodysplastic syndrome. The best results for RT-HCT have been reported for patients with disease that is in remission, indolent and chemosensitive, and with a strong graft-versus-malignancy effect. Chronic graft-versus-host disease seems to correlate with a lower relapse rate and better PFS. RT-HCT is inferior when performed in poor risk or advanced disease, due to high relapse rates. A search for novel strategies that includes the most appropriate conditioning regimens and post-transplant immunomodulation protocols with more intensive anti-malignancy activity but limited toxicity is in progress. This review provides an update on the results of clinical studies of RT-HCT, and discusses possible indications and investigative strategies for improving the clinical outcomes of RT-HCT for the major hematological malignancies.

Ruxolitinib: an oral Janus kinase 1 and Janus kinase 2 inhibitor in the management of myelofibrosis

Myelofibrosis (MF), polycythemia vera (PV), and essential thrombocythemia (ET) are referred to as the classic Philadelphia chromosome (BCR-ABL1)-negative myeloproliferative neoplasms. Although each has distinct pathologic features, all 3 display alterations in Janus kinase (JAK) signal transduction activator of transcription signaling. Myelofibrosis is the most serious of the 3, associated with shortened survival (median survival, 5-7 years); bone marrow failure with anemia; progressive splenomegaly; and chronic, burdensome symptoms, including fatigue, night sweats, itching, abdominal discomfort, loss of appetite/early satiety, unintentional weight loss, and bone, chest, and abdominal pain. Treatments for MF have been mainly palliative, with the exception of allogeneic stem cell transplantation, which, although potentially curative, is feasible only in a small subpopulation of patients. In November 2011, ruxolitinib, an inhibitor of JAK1 and JAK2, was approved by the US Food and Drug Administration for the treatment of intermediate- or high-risk MF, including primary MF, post-PV MF, and post-ET MF. In clinical trials, ruxolitinib was shown to reduce spleen volume and improve MF-related symptoms and quality-of-life measures. Evidence also suggests that ruxolitinib therapy has a survival advantage over placebo and best available therapy. Thrombocytopenia and anemia were the most common adverse events with treatment. Ongoing trials are assessing the efficacy and safety of ruxolitinib therapy in patients with PV and ET.

JAK2 Allele Burden in the Myeloproliferative Neoplasms: Effects on Phenotype, Prognosis and Change with Treatment

The field of Philadelphia-chromosome-negative chronic myeloproliferative neoplasms (MPNs) has recently witnessed tremendous advances in the basic knowledge of disease pathophysiology that followed the identification of mutations in JAK2 and MPL. These discoveries led to a revision of the criteria employed for diagnosis by the World Health Organization. The prognostic role of the JAK2V617F mutation and of its allelic burden has been the objective of intensive research using a variety of cellular and animal models as well as in large series of patients. While a definitive position cannot yet been taken on all of the issues, there is a consensus that the presence of higher V617F allele burden, that is on the basis of a stronger activation of intracellular signalling pathways, is associated with the clinical phenotype of polycythemia vera and with defined haematological and clinical markers indicative of a more aggressive phenotype. On the other hand, a low allele burden in myelofibrosis is associated with reduced survival. Finally, a significant reduction of JAK2 V617F allele burden has been demonstrated in patients treated with interferon, while the effects of novel JAK1 and JAK2 inhibitors have not yet been fully ascertained.

Myelofibrosis: an update on current pharmacotherapy and future directions

INTRODUCTION

Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by symptoms mainly derived from anemia and splenomegaly and constitutional symptoms and associated with a median survival around 6 years. Allogeneic stem cell transplantation (allo-SCT) remains the only curative therapy of MF but is applicable to a minority of patients. Discovery of the JAK2 mutation has provided the basis for the introduction of a new class of drugs, the JAK inhibitors, in the treatment of MF.

AREAS COVERED

A literature review on the therapy of MF has been performed through a PubMed search, with special attention being paid to the available data on transplantation, the JAK inhibitors, and other new drugs.

EXPERT OPINION

Conventional therapy of MF is usually adjusted to the predominant clinical symptoms in each patient, and its impact on survival is limited. Reduced-intensity conditioning regimens have increased the number of patients eligible for allo-SCT, but this procedure is still associated with substantial morbidity and mortality. The JAK inhibitors, such as ruxolitinib, can achieve profound symptomatic relief of the splenomegaly and the constitutional symptoms. However, they often accentuate the anemia and do not reduce the JAK2 allele burden, therefore lacking the potential to modify the natural history of MF.

The evolving treatment paradigm in myelofibrosis

Myelofibrosis (MF) is a BCR-ABL1-negative myeloproliferative neoplasm diagnosed de novo or developed from essential thrombocythemia (ET) or polycythemia vera (PV). Average survival of a patient with MF is 5-7 years. Disease complications include fatigue, early satiety, pruritus, painful splenic infarcts, infections and leukemic transformation. Allogeneic hematopoietic stem cell transplant (HSCT) is the only potentially curative option for MF, but carries a risk of treatment-related mortality and is reserved for the few high-risk patients fit enough to endure the procedure. Other traditional therapies are palliative and supported by few randomized, controlled trials; thus, novel treatment strategies are needed. Discovery of the Janus kinase 2 (JAK2) gain-of-function mutation, JAK2V617F, in the majority (50-60%) of patients with MF led to increased understanding of the biology underlying MF and the development of JAK2 inhibitors to treat MF. Recent Food and Drug Administration (FDA) approval of the first JAK2 inhibitor, ruxolitinib, signaled a new era for treatment of MF. Additional JAK2 inhibitors, such as SAR302503, may become commercially available in the near future, and their distinct pharmacologic and efficacy profiles will help determine their use across the patient population. Data on JAK2 inhibitors, their role in an evolving treatment paradigm, and future directions for treatment of MF are discussed.

Primary myelofibrosis: 2013 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm characterized by stem cell-derived clonal myeloproliferation, abnormal cytokine expression, bone marrow fibrosis, anemia, splenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.

DIAGNOSIS

Diagnosis is based on bone marrow morphology. The presence of fibrosis, JAK2/MPL mutation, or +9/13q- cytogenetic abnormality is supportive but not essential for diagnosis. Prefibrotic PMF mimics essential thrombocythemia in its presentation and the distinction is prognostically relevant. Differential diagnosis of myelofibrosis should include chronic myeloid leukemia, myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia.

RISK STRATIFICATION

The Dynamic International Prognostic Scoring System-plus (DIPSS-plus) prognostic model for PMF can be applied at any point during the disease course and uses eight independent predictors of inferior survival: age >65 years, hemoglobin <10 g/dL, leukocytes >25 × 10⁹/L, circulating blasts ≥ 1%, constitutional symptoms, red cell transfusion dependency, platelet count <100 × 10⁹/L, and unfavorable karyotype (i.e., complex karyotype or sole or two abnormalities that include +8, -7/7q-, i(17q), inv(3), -5/5q-, 12p-, or 11q23 rearrangement). The presence of 0, 1, "2 or 3," and ≥ 4 adverse factors defines low, intermediate-1, intermediate-2, and high-risk disease with median survivals of approximately 15.4, 6.5, 2.9, and 1.3 years, respectively. A >80% two-year mortality is predicted by monosomal karyotype, inv(3)/i(17q) abnormalities, or any two of circulating blasts >9%, leukocytes ≥ 40 × 10⁹/L or other unfavorable karyotype. Most recently, mutations involving ASXL1, SRSF2, EZH2, and IDH1/2 or increased plasma IL-2R, IL-8, or serum-free light chain levels have been shown to adversely affect survival.

RISK-ADAPTED THERAPY

Observation alone is adequate for asymptomatic low/intermediate-1 risk disease. Allogeneic stem cell transplantation (ASCT) is often considered for high risk disease. Conventional or experimental drug therapy is reasonable for symptomatic intermediate-1 or intermediate-2 risk disease; however, ASCT is an acceptable treatment option for such patients in the presence of ASXL1 or other prognostically adverse mutations. Splenectomy and low-dose radiotherapy are used for drug-refractory splenomegaly. Radiotherapy is also used for the treatment of non-hepatosplenic EMH, PMF-associated pulmonary hypertension, and extremity bone pain.

Reduced-intensity hematopoietic stem cell transplants for malignancies: harnessing the graft-versus-tumor effect

Allogeneic hematopoietic cell transplantation combines the power of cytotoxic chemo/radiotherapy with the ability of the new immune system to seek out and destroy tumor cells. However, administration of such myeloablative transplants is fraught with risks, some of which are related to the intensive conditioning regimens. Reductions in the intensity of the administered cytotoxic therapy have demonstrated that under some circumstances, the burden of fighting tumor and enhancing stem cell engraftment can be shouldered mostly by the transplanted immune system. Reduced intensity has allowed a potentially curative therapy for hematologic malignancies to be offered to an expanded patient population. Ongoing research seeks to enhance the safety and power of this form of allogeneic immunotherapy.

Allogeneic hematopoietic cell transplantation for myelodysplastic syndrome: the past decade

Hematopoietic cell transplantation (HCT) is the only therapy with curative potential for patients with myelodysplastic syndrome. Many conditioning regimens have been developed that, along with the use of cord blood or HLA-haploidentical donors, allow doctors to offer HCT to a growing proportion of patients. New classification schemes identify more narrowly characterized risk groups, which may facilitate decisions with regard to HCT. Disease stage and cytogenetics remain the major determinants of HCT outcome. The use of peripheral blood progenitor cells may offer an advantage over marrow for engraftment and relapse prevention, but graft-versus-host disease remains a problem. The age of patients undergoing HCT has increased significantly over the past 25 years, and comorbid conditions are the major patient characteristic impacting transplant success. Recent studies show that drugs used in the non-HCT setting may be beneficial in the context of HCT.

Donor lymphocyte infusions and second transplantation as salvage treatment for relapsed myelofibrosis after reduced-intensity allografting

Thirty myelofibrosis patients (21 males, nine females) with relapse (n = 27) or graft-rejection (n = 3) after dose-reduced allografting underwent a salvage strategy including donor lymphocyte infusions (DLIs) and/or second allogeneic haematopoietic stem cell transplantation (HSCT). Twenty-six patients received a median number of three (range, 1-5) DLIs in a dose-escalated mode starting with a median dose of 1·2 × 10(6) (range, 0·003-8 × 10(6) ) up to median dose of 40 × 10(6) T-cells/kg (range, 10-130 × 10(6) ). 10/26 patients (39%) achieved complete response (CR) to DLIs. Acute (grade II-IV) and chronic graft-versus-host (GvHD) disease occurred in 12% and 36% cases. Thirteen non-responders to DLI and four patients who did not receive DLI due to graft-rejection or acute transformation of the blast phase underwent a second allogeneic HSCT from alternative (n = 15) or the same (n = 2) donor. One patient (6%) experienced primary graft-failure and died. Acute (II-IV) and chronic GvHD were observed in 47% and 46% of patients. Overall responses after second HSCT were seen in 12/15 patients (80%: CR: n = 9, partial response: n = 3). The 1-year cumulative incidence of non-relapse mortality for recipients of a second allograft was 6%, and the cumulative incidence of relapse was 24%. After a median follow-up of 27 months, the 2-year overall survival and progression-free survival for all 30 patients was 70% and 67%, respectively. In conclusion, our two-step strategy, including DLI and second HSCT for non-responding or ineligible patients, is an effective and well-tolerated salvage approach for patients relapsing after reduced-intensity allograft after myelofibrosis.

Improving survival trends in primary myelofibrosis: an international study

PURPOSE

Despite the lack of major improvements in the treatment of primary myelofibrosis (PMF), there are recent indications that the survival of patients might have increased over the years. This study was aimed at ascertaining whether survival prolongation has actually occurred in PMF.

PATIENTS AND METHODS

A total of 802 patients diagnosed with PMF in four European countries were compared for the presentation of features and survival according to the diagnostic periods 1980 to 1995 (n = 434) and 1996 to 2007 (n = 368); relative survival was estimated for the two groups.

RESULTS

Patients diagnosed between 1996 and 2007 more often had constitutional symptoms (31% v 23%) but a lower incidence of marked anemia (31% v 39%), leukocytosis greater than 25 × 10(9)/L (9% v 13%), and blood blasts (27% v 33%); risk distribution was comparable between the two groups. Median survival was 4.6 years (95% CI, 4.0 to 5.1) for patients from 1980 to 1995 and 6.5 years (95% CI, 5.5 to 7.4) for patients from 1996 to 2007 (P < .001). The latter group of patients showed improved relative survival, especially for women, patients younger than age 65 years, and patients with low or intermediate-1-risk disease. Rates of PMF-attributable mortality at 5 and 10 years were significantly lower in the second period; this reduction in disease-specific mortality occurred across all patient subgroups, except in intermediate-2-risk or high-risk patients.

CONCLUSION

Survival of PMF is steadily improving, except in patients in poor-risk categories. This observation must be taken into account at the time of evaluating the survival impact of newer therapies for PMF, which are currently being tested in these patient subpopulations.

Allogeneic cord hematopoietic stem cell transplantation in an infant with primary myelofibrosis

Primary myelofibrosis (PMF) is rare in children. An allogeneic hematopoietic stem cell transplantation (HSCT) is the only known curative therapy for severe cases. Here, we report the case of a female infant with PMF treated with allogeneic HSCT using an unrelated cord blood unit. She had successful reversal of her disease, but experienced complications related to transplant. This is the seventh reported case of HSCT for PMF in children, and the second using umbilical cord blood. We conclude that cord HSCT is a useful curative treatment option in children with PMF, but that efforts must be taken to reduce complications.

Allogeneic hematopoietic cell transplantation for myelofibrosis in the era of JAK inhibitors

The discovery of JAK2617F mutation paved the way for the development of small molecule inhibitors of JAK1/2 resulting in first approved JAK1/2 inhibitor, ruxolitinib, for the treatment of patients with myelofibrosis (MF). Although JAK1/2 inhibitor therapy is effective in decreasing the burden of symptoms associated with splenomegaly and MF-related constitutional symptoms, it is neither curative nor effective in reducing the risk of leukemic transformation. Presently, allogeneic hematopoietic cell transplantation (HCT) is the only curative therapy for MF. A significant risk of regimen-related toxicities, graft failure, and GVHD are major barriers to the success of HCT in MF. Because of significant HCT-associated morbidity and mortality, divergent opinions regarding its appropriate role in this clinical situation have emerged. In this review, the risk-benefit ratios of modern drug therapy compared with HCT in MF patients are analyzed. A risk-adapted approach individualized to each patient's biologic characteristics and comorbidities is described, which is currently warranted in determining optimal treatment strategies for patients with MF. Inclusion of JAK1/2 inhibitor therapy in future transplant conditioning regimens may provide an opportunity to overcome some of these barriers, resulting in greater success with HCT for MF patients.

Replacement of hematopoietic system by allogeneic stem cell transplantation in myelofibrosis patients induces rapid regression of bone marrow fibrosis

Bone marrow fibrosis is a hallmark of primary and post ET/PV myelofibrosis. To investigated the impact of replacement of the hematopoietic system in myelofibrosis patients by allogeneic stem cell transplantation on bone marrow fibrosis, we studied bone marrow fibrosis on bone marrow samples from 24 patients with myelofibrosis before and after dose-reduced conditioning followed by allogeneic stem cell transplantation from related or unrelated donor. Using the European Consensus on Grading Bone Marrow Fibrosis, before allografting all patients had advanced fibrosis MF-2 (n = 13) or MF-3 (n = 11). After transplantation, a complete (MF-0) or nearly complete (MF-1) regression of bone marrow fibrosis was seen in 59 % at day +100, in 90 % at day +180, and in 100 % at day +360. No correlation between occurrence of acute graft-versus-host disease, and fibrosis regression on day +180 was seen. We conclude that dose-reduced conditioning, followed by allogeneic stem cell transplantation, resulted in a rapid resolution of bone-marrow fibrosis suggesting the bone marrow fibrogenesis is a highly dynamic rather than static process in patients with myelofibrosis.

Myelofibrosis 2012: it's complicated

Major advances in myeloproliferative neoplasms in the last decade have cast light on their complexity. The identification of JAK2 (V617F) briefly promised a unifying mechanism of pathogenesis with a single pathway that could be efficiently targeted. Instead, there have been major advances in understanding acquired and background genetic and epigenetic contributors to this group of disorders, with refined risk prediction models and experimental therapeutics that have provided a more nuanced model of disease. In aggregate these observations likely explain the heterogeneity of these disorders and their generally unpredictable response to therapy. Molecular studies, beginning with the identification of JAK2 (V617F), have led to a concept of MPN subtypes existing on a continuum, and additional discoveries such as TET2 and EZH2 mutations have provided the molecular underpinnings to begin to explain overlapping phenotypes in myeloid malignancies more generally. In many ways the pace of molecular discovery is outstripping our ability to integrate these observations into clinical care, both in terms of molecular diagnostics and medical decision making. This review will attempt to summarize, within a clinical context, our evolving understanding of myeloproliferative neoplasms. It focuses on biology, histopathology, prognostic scoring systems, stem cell transplantation as well as selected clinical/preclinical therapeutic observations.

How I treat polycythemia vera

Polycythemia vera (PV) is a clonal disorder characterized by unwarranted production of red blood cells. In the majority of cases, PV is driven by oncogenic mutations that constitutively activate the JAK-STAT signal transduction pathway, such as JAK2 V617F, or exon 12 mutations or LNK mutations. Diagnosis of PV is based on the WHO criteria. Diagnosis of post-PV myelofibrosis is established according to the International Working Group for Myeloproliferative Neoplasms Research and Treatment criteria. Different clinical presentations of PV are discussed. Prognostication of PV is tailored to the most frequent complication during follow-up, namely, thrombosis. Age older than 60 years and prior history of thrombosis are the 2 main risk factors for disease stratification. Correlations are emerging between leukocytosis, JAK2(V617F) mutation, BM fibrosis, and different outcomes of PV, which need to be confirmed in prospective studies. In my practice, hydroxyurea is still the "gold standard" when cytoreduction is needed, even though pegylated IFN-alfa-2a and ruxolitinib might be useful in particular settings. Results of phase 1 or 2 studies concerning these latter agents should however be confirmed by the ongoing randomized phase 3 clinical trials. In this paper, I discuss the main problems encountered in daily clinical practice with PV patients regarding diagnosis, prognostication, and therapy.

Allogeneic stem cell transplant for myelofibrosis patients over age 60: likely impact of the JAK2 inhibitors

The myeloproliferative neoplasm, myelofibrosis (MF), has only one therapeutic intervention that is potentially curative in these individuals, specifically that of allogeneic stem cell transplantation (ASCT). ASCT has been utilized up to this juncture, primarily in younger individuals with higher risk disease. There is more limited data on outcomes in individuals over the age of 60 years. The choice of an individualized therapeutic intervention for a patient with MF is a very complex issue and is dependent on several factors. The first factor being their overall prognosis with their illness (which can vary from a median of 2 years in high-risk patients to over 10 years in low-risk patients) and the potential impact of a therapeutic intervention not only on survival but also on quality of life. Current available therapies have been strictly palliative for disease-associated anemia and/or splenomegaly. At present, we have a new generation of inhibitors of JAK2 (Ruxolitinib, CYT387, SB1518, TG101348, with others in development), which have been shown to improve splenomegaly, improve symptomatic burden of illness and improve quality of life. In addition, these inhibitors of JAK2 may have an impact on the natural history of MF, but confirmation of the presence and degree of this impact is still pending. Clinical availability of JAK2 inhibitors may alter the timing of transplant in marginal transplant candidates (that is, those over the age of 60), may have a role preceding ASCT to improve spleen size and performance status before transplant and might be frontline therapy in intermediate and high-risk patients who are not candidates for ASCT.

Dynamic International Prognostic Scoring System scores, pre-transplant therapy and chronic graft-versus-host disease determine outcome after allogeneic hematopoietic stem cell transplantation for myelofibrosis

BACKGROUND

Myelofibrosis is a myeloproliferative stem cell disorder curable exclusively by allogeneic hematopoietic stem cell transplantation and is associated with substantial mortality and morbidity. The aim of this study was to assess disease-specific and transplant-related risk factors that influence post-transplant outcome in patients with myelofibrosis.

DESIGN AND METHODS

We retrospectively assessed 76 consecutive patients with primary (n=47) or secondary (n=29) myelofibrosis who underwent bone marrow (n=6) or peripheral blood stem cell (n=70) transplantation from sibling (n=30) or unrelated (n=46) donors between January 1994 and December 2010. The median follow-up of surviving patients was 55 ± 7.5 months.

RESULTS

Primary graft failure occurred in 5% and the non-relapse mortality rate at 1 year was 28%. The relapse-free survival rate was 50% with a relapse rate of 19% at 5 years. The use of pharmacological pre-treatment and the post-transplant occurrence of chronic graft-versus-host disease were significant independent unfavourable risk factors for post-transplant survival in multivariate analysis. Using the Dynamic International Prognostic Scoring System for risk stratification, low-risk patients had significantly better overall survival (P=0.014, hazard ratio 1.4) and relapse-free survival (P=0.02, hazard ratio 1.3) compared to the other risk groups of patients. The additional inclusion of thrombocytopenia, abnormal karyotype and transfusion need (Dynamic International Prognostic Scoring System Plus) resulted in a predicted 5-year overall survival of 100%, 51%, 54% and 30% for low, intermediate-1, intermediate-2 and high-risk groups, respectively. The relapse incidence was significantly higher in the absence of chronic graft-versus-host disease (P=0.006), and pharmacological pre-treatment (n=43) was associated with reduced relapse-free survival (P=0.001).

CONCLUSIONS

The data corroborate a strong correlation between alloreactivity and long-term post-transplant disease control and confirm an inverse relationship between disease stage, pharmacotherapy and outcome after allogeneic hematopoietic stem cell transplantation for myelofibrosis. The Dynamic International Prognostic Scoring System was demonstrated to be useful for risk stratification of patients with myelofibrosis who are to undergo hematopoietic stem cell transplantation.

Allogeneic stem cell transplantation for myelofibrosis in 2012

Myelofibrosis (MF) is a heterogeneous disease for which long-term, effective medical therapeutic options are currently limited. The role of allogeneic haematopoietic stem cell transplant (AHSCT) in this population, many of whom are elderly, often provides a challenge with regard to the identification of suitable candidates, timing of transplantation in the disease course and choice of conditioning regimen. This review summarizes key findings from published data concerning AHSCT in MF and attempts to provide a state of the art approach to MF-AHSCT in 2012. In addition, we postulate on how the era of JAK inhibition might impact on transplantation for MF.

Outcome of patients activating an unrelated donor search: the impact of transplant with reduced intensity conditioning in a large cohort of consecutive high-risk patients

An unrelated donor (UD) search was submitted to the Italian Bone Marrow Donor Registry between February 2002 and December 2004, for 326 consecutive patients with hematological malignancies, eligible for a reduced intensity conditioning (RIC) UD transplant. Only two regimens were allowed: melphalan, alemtuzumab, fludarabine and total body irradiation of 200 cGy (regimen A) and thiotepa, cyclophosphamide, anti-thymocyte globulin (regimen B). The outcome of patients receiving an UD transplant (n=121) was compared with patients who did not find a donor (n=205), in a time dependent analysis, correcting for time to transplant. The median follow up from activation of donor search was 6.1 years. UD transplant was associated with a significantly better survival in patients with acute leukemia and non-Hodgkin's lymphoma (NHL) whereas only a favorable trend was documented for Hodgkin's disease. No survival benefit was registered for chronic leukemias. The outcome of the two different conditioning regimens was comparable, in terms of survival, transplant-related mortality and graft versus host disease. In conclusion, finding an UD and undergoing a RIC transplant significantly improves survival of patients with acute leukemia and NHL. The advantage is less clear for HD and chronic leukemias. The role of different conditioning regimens remains to be elucidated by prospective clinical trials.

How to manage the transplant question in myelofibrosis

Allogeneic stem cell transplantation remains the only curative therapy for myelofibrosis. Despite advances in transplant, the morbidity and the mortality of the procedure necessitate careful patient selection. In this manuscript, we describe the new prognostic scoring system to help select appropriate patients for transplant and less aggressive therapies. We explore the advances in non-transplant therapy, such as with investigational agents. We review the blossoming literature on results of myeloablative, reduced intensity and alternative donor transplantation. Finally, we make recommendations for which patients are most likely to benefit from transplantation.

Spleen deflation and beyond: the pros and cons of Janus kinase 2 inhibitor therapy for patients with myeloproliferative neoplasms

The myeloproliferative neoplasms (MPNs) essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (MF) are malignancies that frequently harbor the recurrent somatic point mutation JAK2(V617F). The discovery of this mutation has fueled the development of Janus kinase 2 (JAK2) inhibitors. Available results have indicated that JAK2 inhibitors are particularly effective at reducing spleen size. However, the activity of these agents is multifaceted and also involves a marked improvement of systemic symptoms and, for those agents with dual JAK1 and JAK2 inhibitory activity, a marked reduction in the levels of circulating cytokines involved in the pathogenesis of the disease. Because JAK2 inhibitors are not specific for JAK2(V617F), responses have also been observed in JAK2(V617F) -negative MPNs because of the inhibition of wild-type JAK2, which is also likely responsible for the induction of cytopenias in patients with MF and for the normalization of peripheral blood counts observed in patients with ET or PV. Given the distinct mortality and morbidity associated with ET, PV, and MF, the use of JAK2 inhibitors appears reasonable for patients with MF as well as for those with ET or PV who have become resistant or intolerant to hydroxyurea. Ongoing randomized, placebo-controlled, phase 3 trials will further delineate the role of these agents in the management of patients with MPNs. The pros and cons of JAK2 kinase inhibitor therapy are herein discussed.

Risk models predicting survival after reduced-intensity transplantation for myelofibrosis

To define a prognostic model for predicting outcome of reduced-intensity allogeneic stem cell transplantation (RIC-ASCT) for myelofibrosis we evaluated 150 homogeneously treated patients and developed a new risk score for overall survival (OS). In a multivariate Cox model for OS, only JAK2 V617F wild-type, age ≥57 years and constitutional symptoms were independently predictive for OS (Hazard Ratio: 2·02; 2·43 and 2·80 respectively). Depending on the presence of one, two or all of these factors, HR of death was 3·08; 4·70 and 16·61 respectively (P < 0·001). This score was compared to the Lille, Cervantes, International Prognostic Scoring System (IPSS), dynamic IPSS (DIPSS) and modified European Blood and Marrow Transplantation Group (EBMT) scores. Lille score correlated significantly with OS but discriminated poorly between the intermediate and high-risk groups (5-year OS 56% and 51% respectively). IPSS and DIPSS correlated significantly with OS but differences between intermediate-1 and intermediate-2 groups were not significant (5-year OS 78% vs. 78% and 70%, 60% respectively). Modified EBMT and Cervantes models did not predict OS post-ASCT. In conclusion, a simple model which includes: age, JAK2 V617F-status and constitutional symptoms can clearly separate distinct risk groups and can be used in addition to the Lille model to predict OS after RIC-ASCT for myelofibrosis.

The Dynamic International Prognostic Scoring System for myelofibrosis predicts outcomes after hematopoietic cell transplantation

Studies by the International Working Group showed that the prognosis of myelofibrosis patients is predicted by the Dynamic International Prognostic Scoring System (DIPSS) risk categorization, which includes patient age, constitutional symptoms, hemoglobin, leukocyte count, and circulating blasts. We evaluated the prognostic usefulness of the DIPSS in 170 patients with myelofibrosis, 12 to 78 years of age (median, 51.5 years of age), who received hematopoietic cell transplantation (HCT) between 1990 and 2009 from related (n = 86) or unrelated donors (n = 84). By DIPSS, 21 patients had low-risk disease, 48 had intermediate-1, 50 had intermediate-2, and 51 had high-risk disease. Five-year incidence of relapse, relapse-free survival, overall survival, and nonrelapse mortality for all patients were 10%, 57%, 57%, and 34%, respectively. Among patients with DIPSS high-risk disease, the hazard ratio for post-HCT mortality was 4.11 (95% CI, 1.44-11.78; P = .008), and for nonrelapse mortality was 3.41 (95% CI, 1.15-10.09; P = .03) compared with low-risk patients. After a median follow-up of 5.9 years, the median survivals have not been reached for DIPSS risk groups low and intermediate-1, and were 7 and 2.5 years for intermediate-2 and high-risk patients, respectively. Thus, HCT was curative for a large proportion of patients with myelofibrosis, and post-HCT success was dependent on pre-HCT DIPSS classification.

How to manage polycythemia vera

My diagnostic approach in case of isolated erythrocytosis is based on the visit and the interview of patients, and on checking the causes of secondary erythrocytosis. If causes of secondary erythrocytosis are not evident and serum erythropoietin level is low-normal, I study JAK2 mutations. In the case of a patient with erythrocytosis and other signs of myeloproliferation, such as leukocytosis, thrombocytosis or splenomegaly, the diagnosis of polycythemia vera (PV) is likely, and I test serum erythropoietin and JAK2 mutations first. I stratify patients at diagnosis of PV according to age and history of thrombosis. I start hydroxyurea for patients who are at a high risk of thrombosis (that is, with one or two risk factors), while I continue only phlebotomy in other cases. All PV patients, if not contraindicated, receive aspirin. I follow up patients monthly until normalization of their blood cell counts or splenomegaly, and afterwards every 2 months with visit, cell blood count and blood smear evaluation. After diagnosis, I perform bone marrow biopsy only in the case of clinical signs of disease evolution.

Advances in the understanding and management of primary myelofibrosis

PURPOSE OF REVIEW

Identification of the JAK2V617F mutation in 2005 boosted basic and clinical research in primary myelofibrosis (PMF) and other Philadelphia-negative chronic myeloproliferative neoplasms. We herein review the recent contributions to the understanding and management of PMF.

RECENT FINDINGS

In addition to the JAK2V617F mutation, different genetic markers have recently been discovered in PMF, the most relevant ones being the mutations in the thrombopoietin (MPL), TET2, and EZH2 genes. From the clinical point of view, attention has recently been paid to thrombosis as a relevant complication of PMF and new prognostic models for this disease have been created and refined. Regarding therapy, reduced intensity conditioning regimens have allowed the possibility of performing allogeneic stem cell transplantation in older PMF patients, whereas the first clinical trials with JAK2 inhibitors have shown their efficacy in splenomegaly and constitutional symptoms.

SUMMARY

The molecular biology of PMF is more complex than initially believed. Due to its associated mortality risk, stem cell transplantation should be restricted to patients with poor prognostic features. The JAK2-inhibitors are promising as a palliative treatment of PMF. In conclusion, the once neglected PMF has become a very active field of research, which will hopefully soon translate into relevant therapeutic advances.

Primary myelofibrosis: 2012 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm characterized by stem cell-derived clonal myeloproliferation, abnormal cytokine expression, bone marrow fibrosis, anemia, splenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.

DIAGNOSIS

Diagnosis is based on bone marrow morphology. The presence of fibrosis, JAK2/MPL mutation or +9/13q- cytogenetic abnormality is supportive but not essential for diagnosis. Prefibrotic PMF mimics essential thrombocythemia in its presentation and the distinction is prognostically relevant. Differential diagnosis of myelofibrosis should include chronic myelogenous leukemia, myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia.

RISK STRATIFICATION

The Dynamic International Prognostic Scoring System-plus (DIPSS-plus) prognostic model for PMF can be applied at any point during the disease course and uses eight independent predictors of inferior survival: age >65 years, hemoglobin <10 g/dL, leukocytes >25 × 10(9) /L, circulating blasts ≥1%, constitutional symptoms, red cell transfusion dependency, platelet count <100 × 10(9) /L, and unfavorable karyotype (i.e., complex karyotype or sole or two abnormalities that include +8, -7/7q-, i(17q), inv(3), -5/5q-, 12p- or 11q23 rearrangement). The presence of 0, 1, "2 or 3," and ≥4 adverse factors defines low, intermediate-1, intermediate-2, and high-risk disease with median survivals of ~15.4, 6.5, 2.9, and 1.3 years, respectively. A >80% two-year mortality is predicted by monosomal karyotype, inv(3)/i(17q) abnormalities, or any two of circulating blasts >9%, leukocytes ≥40 × 10(9) /L or other unfavorable karyotype.

RISK-ADAPTED THERAPY

Observation alone is adequate for asymptomatic low/intermediate-1 risk disease. Allogeneic stem cell transplantation or experimental drug therapy is considered for intermediate-2/ high risk disease. Conventional or experimental drug therapy is reasonable for symptomatic intermediate-1 risk disease. Splenectomy and low-dose radiotherapy are used for drug-refractory splenomegaly. Radiotherapy is also used for the treatment of non-hepatosplenic EMH, PMF-associated pulmonary hypertension, and extremity bone pain.

How I treat splenomegaly in myelofibrosis

Symptomatic splenomegaly, a frequent manifestation of myelofibrosis (MF), represents a therapeutic challenge. It is frequently accompanied by constitutional symptoms and by anemia or other cytopenias, which make treatment difficult, as the latter are often worsened by most current therapies. Cytoreductive treatment, usually hydroxyurea, is the first-line therapy, being effective in around 40% of the patients, although the effect is often short lived. The immunomodulatory drugs, such as thalidomide or lenalidomide, rarely show a substantial activity in reducing the splenomegaly. Splenectomy can be considered in patients refractory to drug treatment, but the procedure involves substantial morbidity as well as a certain mortality risk and, therefore, patient selection is important. For patients not eligible for splenectomy, transient relief of the symptoms can be obtained with local radiotherapy that, in turn, can induce severe and long-lasting cytopenias. Allogeneic hemopoietic stem cell transplantation is the only treatment with the potential for curing MF but, due to its associated morbidity and mortality, is usually restricted to a minority of patients with poor risk features. A new class of drugs, the JAK2 inhibitors, although also palliative, are promising in the splenomegaly of MF and will probably change the therapeutic algorithm of this disease.

Predictors of greater than 80% 2-year mortality in primary myelofibrosis: a Mayo Clinic study of 884 karyotypically annotated patients

DIPSS-plus (the Dynamic International Prognostic Scoring System-plus) includes 8 risk factors for survival in primary myelofibrosis. In the present study of 884 karyotypically annotated patients with primary myelofibrosis, we sought to identify 1 or 2 parameters that can reliably predict death in the first 2 years of disease. After a median of 8.2 years from time of referral to the Mayo Clinic, 564 deaths (64% of patients in the study) had been recorded. Risk factors associated with > 80% 2-year mortality included monosomal karyotype, inv(3)/i(17q) abnormalities, or any 2 of the following: circulating blasts > 9%, leukocytes ≥ 40 × 10(9)/L, or other unfavorable karyotype. Patients with any 1 of these risk profiles (n = 52) displayed significantly shorter overall survival than those otherwise belonging to a high-risk category per DIPSS-plus (n = 298); respective median survivals were 9 and 23 months (hazard ratio 2.2, 95% confidence interval 1.6-3.1; P < .01). The present information complements DIPSS-plus in the selection of primary myelofibrosis patients for high-risk treatment approaches.