Choosing between stem cell therapy and drugs in myelofibrosis

Repeat Endoscopy Affects Patient Management in Gastrointestinal Graft-Versus-Host Disease

Graft versus host disease (GVHD) of the gut is associated with significant morbidity and mortality after allogeneic hematopoietic cell transplant (allo-HCT). No guidelines exist regarding repeat endoscopy after failure of first-line treatment with steroids. We aimed to study if repeat endoscopic biopsy can be helpful in these patients to guide treatment decisions. We retrospectively reviewed medical records of all patients who underwent repeat endoscopy for clinical suspicion of gastrointestinal (GI) GVHD after allo-HCT. Of the 318 patients, 24 underwent endoscopy twice after allo-HCT. At first endoscopy, 20 patients (80%) showed abnormal findings: 16 with GVHD alone, 1 with GVHD plus cytomegalovirus (CMV), and 3 with GVHD plus infectious colitis. On repeat endoscopy in these 20 patients with GVHD, 6 showed improvement leading to de-escalation of therapy, 8 showed worsening of GVHD including detection of CMV in 2 patients, and 2 had no histological changes. One patient with simultaneous GVHD and CMV diagnosed on first biopsy, displayed significant improvement leading to de-escalation of therapy. Three patients with GVHD along with infectious colitis on biopsy subsequently showed improvement on repeat biopsy leading to de-escalation of therapy. Among 4 patients with normal findings on first endoscopy, 3 had GVHD and 1 had epstein-barrvirus-associated post-transplant lymphoproliferative disorder (EBV-PTLD) on repeat procedures. This study supports the usefulness of repeat endoscopy in persistently symptomatic patients when there is no improvement after the initial treatment based on the results of the first endoscopy. Repeat endoscopy may guide therapy without significant complications.

Emerging treatments for classical myeloproliferative neoplasms

There has been a major revolution in the management of patients with myeloproliferative neoplasms (MPN), and in particular those with myelofibrosis and extensive splenomegaly and symptomatic burden, after the introduction of the JAK1 and JAK2 inhibitor ruxolitinib. The drug also has been approved as second-line therapy for polycythemia vera (PV). However, the therapeutic armamentarium for MPN is still largely inadequate for coping with patients' major unmet needs, which include normalization of life span (myelofibrosis and some patients with PV), reduction of cardiovascular complications (mainly PV and essential thrombocythemia), prevention of hematological progression, and improved quality of life (all MPN). In fact, none of the available drugs has shown clear evidence of disease-modifying activity, even if some patients treated with interferon and ruxolitinib showed reduction of mutated allele burden, and ruxolitinib might extend survival of patients with higher-risk myelofibrosis. Raised awareness of the molecular abnormalities and cellular pathways involved in the pathogenesis of MPN is facilitating the development of clinical trials with novel target drugs, either alone or in combination with ruxolitinib. Although for most of these molecules a convincing preclinical rationale was provided, the results of early phase 1 and 2 clinical trials have been quite disappointing to date, and toxicities sometimes have been limiting. In this review, we critically illustrate the current landscape of novel therapies that are under evaluation for patients with MPN on the basis of current guidelines, patient risk stratification criteria, and previous experience, looking ahead to the chance of a cure for these disorders.

(18)F-FDG PET/CT for detection of leukemic transformation in myelofibrosis

Myelofibrosis is a rare clonal hematopoietic stem cell disorder characterized by chronic myeloproliferation, atypical megakaryocytic hyperplasia, and potential leukemic transformation. We report a case of leukemic transformation detected by F-FDG PET/CT. A 56-year-old woman with myelofibrosis and newly diagnosed space-occupying lesion of the chest wall underwent whole-body PET/CT for further evaluation. F-FDG PET demonstrated marked tracer uptake within that lesion. Histopathological evaluation revealed myeloid sarcoma evidencing leukemic transformation. F-FDG PET/CT is a valuable tool-enabling sensitive detection of leukemic transformation in myelofibrosis, particularly in case of extramedullary organ involvement.

Assessment of bone marrow inflammation in patients with myelofibrosis: an 18F-fluorodeoxyglucose PET/CT study

PURPOSE

Myelofibrosis is a haematopoietic stem cell neoplasm characterized by bone marrow inflammation, reactive marrow fibrosis and extramedullary haematopoiesis. The aim of this study was to determine if (18)F-FDG PET/CT can be used to noninvasively visualize and quantify the extent and activity of bone marrow involvement.

METHODS

In 30 patients, the biodistribution of (18)F-FDG was analysed by measuring the standardized uptake value in the bone marrow compartment and spleen. Imaging findings were compared with laboratory, cytogenetic and histopathological data.

RESULTS

Retention of (18)F-FDG was observed in bone marrow and spleen. Bone marrow involvement varied, ranging from mildly increased uptake in the central skeleton to extensive uptake in most parts of the skeleton. The extent of bone marrow involvement decreased over time from initial diagnosis (r s  = -0.43, p = 0.019). Metabolic activity of the bone marrow decreased as the histopathological grade of fibrosis increased (r s  = -0.37, p = 0.04). There was a significant positive correlation between the metabolic activity of the bone marrow and that of the spleen (p = 0.04).

CONCLUSION

(18)F-FDG PET/CT is as a promising technique for the quantitation of bone marrow inflammation in myelofibrosis. Our data indicate that the intensity of bone marrow (18)F-FDG uptake decreases as bone marrow fibrosis increases. Further evaluation in prospective studies is required to determine the potential clinical impact and prognostic significance of PET.

Impact of mutational status on outcomes in myelofibrosis patients treated with ruxolitinib in the COMFORT-II study

Improvements in splenomegaly and symptoms in patients receiving ruxolitinib occurred regardless of the mutations that were present. Ruxolitinib relieved the negative impact of prognostically detrimental mutations in myelofibrosis patients from the COMFORT-II study.

Phase II trial of panobinostat, an oral pan-deacetylase inhibitor in patients with primary myelofibrosis, post-essential thrombocythaemia, and post-polycythaemia vera myelofibrosis

Myelofibrosis (MF) is a Philadelphia chromosome-negative stem cell myeloproliferative neoplasm (MPN) associated with cytopenias, splenomegaly, constitutional symptoms, and poor prognosis. MF patients commonly express JAK2 V617F mutation and activation of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signalling. Agents targeting the JAK/STAT pathway have demonstrated efficacy in patients with MF. This study evaluated panobinostat, a pan-deacetylase inhibitor that depletes JAK2 V617F levels and JAK/STAT signalling in MPN cells, in patients with primary MF, post-essential thrombocythaemia MF, and post-polycythaemia vera MF. Patients received panobinostat 40 mg administered three times per week. Dose reductions were permitted for toxicities. The primary endpoint was response rate at 6 months using International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) consensus criteria. Analyses of peripheral blood cells from treated patients revealed that panobinostat inhibited JAK/STAT signalling, decreased inflammatory cytokine levels, and decreased JAK2 V617F allelic burden. However, panobinostat was poorly tolerated at the dose and schedule evaluated, and only 16 of 35 patients completed ≥2 cycles of treatment. One patient (3%) achieved an IWG-MRT response. Common adverse events were thrombocytopenia (71.4%) and diarrhoea (80.0%). Although molecular correlative analyses suggested that panobinostat inhibits key intracellular targets, limited clinical activity was observed because of poor tolerance.

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.

Clinical, histopathologic, and genetic features of pediatric primary myelofibrosis--an entity different from adults

Primary myelofibrosis is a chronic myeloproliferative neoplasm characterized by cytopenias, leukoerythroblastosis, extramedullary hematopoiesis, hepatosplenomegaly and bone marrow fibrosis. Primary myelofibrosis is a rare disorder in adults; children are even less commonly affected by this entity, with the largest pediatric case series reporting on three patients. Most literature suggests spontaneous resolution of myelofibrosis without long term complications in the majority of affected children. We describe the clinical, pathologic, and molecular characteristics and outcomes of nineteen children with primary myelofibrosis treated in our center from 1984 to 2011. Most patients had cytopenia significant enough to require supportive therapy. No child developed malignant transformation and only five of the 19 children (26%) had spontaneous resolution of disease. Sequence analyses for JAK2V617F and MPLW515L mutations were performed on bone marrow samples from 17 and six patients, respectively, and the results were negative. In conclusion, analysis of this large series of pediatric patients with primary myelofibrosis demonstrates distinct clinical, hematologic, bone marrow, and molecular features from adult patients.

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.

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.

EZH2 mutational status predicts poor survival in myelofibrosis

We genotyped 370 subjects with primary myelofibrosis (PMF) and 148 with postpolycythemia vera/postessential thrombocythemia (PPV/PET) MF for mutations of EZH2. Mutational status at diagnosis was correlated with hematologic parameters, clinical manifestations, and outcome. A total of 25 different EZH2 mutations were detected in 5.9% of PMF, 1.2% of PPV-MF, and 9.4% of PET-MF patients; most were exonic heterozygous missense changes. EZH2 mutation coexisted with JAK2V617F or ASXL1 mutation in 12 of 29 (41.4%) and 6 of 27 (22.2%) evaluated patients; TET2 and CBL mutations were found in 2 and 1 patients, respectively. EZH2-mutated PMF patients had significantly higher leukocyte counts, blast-cell counts, and larger spleens at diagnosis, and most of them (52.6%) were in the high-risk International Prognostic Score System (IPSS) category. After a median follow-up of 39 months, 128 patients (25.9%) died, 81 (63.3%) because of leukemia. Leukemia-free survival (LFS) and overall survival (OS) were significantly reduced in EZH2-mutated PMF patients (P = .028 and P < .001, respectively); no such impact was seen for PPV/PET-MF patients, possibly due to the low number of mutated cases. In multivariate analysis, survival of PMF patients was predicted by IPSS high-risk category, a < 25% JAK2V617F allele burden, and EZH2 mutation status. We conclude that EZH2 mutations are independently associated with shorter survival in patients with PMF.

New JAK2 inhibitors for myeloproliferative neoplasms

INTRODUCTION

The discovery of the JAK(V617F) kinase established a common pathogenetic link to the most important types of Philadelphia-chromosome-negative myeloproliferative neoplasms (MPNs): polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). More importantly, the demonstration of constitutive kinase activity emanating from the JAK2 protein provided the rationale for the development of small-molecule JAK2 kinase inhibitors.

AREAS COVERED

Several JAK2 kinase inhibitors are being tested in clinical trials for patients with MPNs. In PMF trials, JAK2 inhibitors have been shown to produce rapid reductions in spleen size and marked improvements in constitutional symptoms and quality of life. In ET and/or PV, JAK2 inhibitors normalize hematocrit, platelets and WBC, and spleen size in a large number of patients that are resistant or intolerant to hydroxyurea. JAK2 inhibitors are not specific for the JAK2V617F mutant protein. Rather, they inhibit the JAK2- signal transducer and activator of transcription (STAT) pathway and therefore any patient with MPN may benefit from therapy regardless of JAK2 mutational status.

EXPERT OPINION

JAK2 inhibitors induce clinically relevant responses in a large proportion of patients with MPNs. Because JAK kinase activation underlies the pathogenesis of other disorders, such as autoimmune and rheumatological disorders, the paradigm of JAK inhibition may translate into novel therapies for a variety of human diseases.

Recombinant interferon-α may retard progression of early primary myelofibrosis: a preliminary report

The limited effects of current treatments of primary myelofibrosis (PM) led us to prospectively evaluate recombinant interferon-α (rIFNα) in "early" PM patients with residual hematopoiesis and only grade 1 or 2 myelofibrosis. Seventeen patients meeting World Health Organization PM diagnostic criteria received either rIFNα-2b 500 000 to 3 million units 3 times weekly, or pegylated rIFNα-2a 45 or 90 μg weekly. International Working Group for Myelofibrosis Research and Treatment criteria for prognosis and response were used. Eleven patients were women and 6 were men. Their median age at diagnosis was 57 years. Eleven patients were low risk and 6 were intermediate-1 risk. Two achieved complete remission, 7 partial, 1 clinical improvement, 4 stable disease, and 3 had progressive disease. Thus, more than 80% derived clinical benefit or stability. Improvement in marrow morphology occurred in 4. Toxicity was acceptable. These results, with documented marrow reversion because of interferon treatment, warrant expanded evaluation.

Experimental therapeutics for patients with myeloproliferative neoplasias

Philadelphia chromosome (Ph)-negative myeloproliferative neoplasms (MPNs) are characterized by stem cell-derived, unrestrained clonal myeloproliferation. The World Health Organization classification system, proposed in 2008, identifies 7 distinct categories of Ph-negative MPNs including essential thrombocythemia (ET); polycythemia vera (PV); primary myelofibrosis (PMF); mastocytosis; chronic eosinophilic leukemia; chronic neutrophilic leukemia; and MPN, unclassifiable. For many years, the treatment of ET, PV, and PMF, the most frequently diagnosed Ph-negative MPNs, has been largely supportive. In recent years, that paradigm has been challenged because of the discovery of a recurrent point mutation in the Janus kinase 2 (JAK2) gene (JAK2(V617F)). This mutation can be detected in the vast majority of patients with PV and approximately half of patients with ET or PMF and serves as both a diagnostic marker as well as representing a putative molecular target for drug development. Several putative targeted agents with significant in vitro JAK2 inhibitory activity and various degrees of JAK2 specificity are currently undergoing clinical evaluation. Furthermore, other investigational non-tyrosine kinase inhibitor approaches such as immunomodulatory agents and pegylated interferon- have also shown promising results in MPNs.

Janus kinase inhibitors for the treatment of myeloproliferative neoplasias and beyond

Recent advances in our understanding of the pathogenesis of the Philadelphia chromosome-negative myeloproliferative neoplasms, polycythaemia vera, essential thrombocythaemia and myelofibrosis have led to the identification of the mutation V617F in Janus kinase (JAK) as a potential therapeutic target. This information has prompted the development of ATP-competitive JAK2 inhibitors. Therapy with JAK2 inhibitors may induce rapid and marked reductions in spleen size and can lead to remarkable improvements in constitutional symptoms and overall quality of life. Because JAKs are involved in the pathogenesis of inflammatory and immune-mediated disorders, JAK inhibitors are also being tested in clinical trials in patients with rheumatoid arthritis and psoriasis, as well as for the treatment of other autoimmune diseases and for the prevention of allograft rejection. Preliminary results indicate that these agents hold great promise for the treatment of JAK-driven disorders.

Refined cytogenetic-risk categorization for overall and leukemia-free survival in primary myelofibrosis: a single center study of 433 patients

We have previously identified sole +9, 13q- or 20q-, as ‘favorable' and sole +8 or complex karyotype as ‘unfavorable' cytogenetic abnormalities in primary myelofibrosis (PMF). In this study of 433 PMF patients, we describe additional sole abnormalities with favorable (chromosome 1 translocations/duplications) or unfavorable (−7/7q-) prognosis and also show that other sole or two abnormalities that do not include i(17q), −5/5q-, 12p-, inv(3) or 11q23 rearrangement are prognostically aligned with normal karyotype, which is prognostically favorable. These findings were incorporated into a refined two-tired cytogenetic-risk stratification: unfavorable and favorable karyotype. The respective 5-year survival rates were 8 and 51% (hazard ratio (HR): 3.1, 95% confidence interval (CI): 2.2–4.3; P<0.0001). Multivariable analysis confirmed the International Prognostic Scoring System (IPSS)-independent prognostic value of cytogenetic-risk categorization and also identified thrombocytopenia (platelets <100 × 10⁹/l) as another independent predictor of inferior survival (P<0.0001). A similar multivariable analysis showed that karyotype (P=0.001) and platelet count (P=0.04), but not IPSS (P=0.27), predicted leukemia-free survival; the 5-year leukemic transformation rates for unfavorable versus favorable karyotype were 46 and 7% (HR: 5.5, 95% CI: 2.5–12.0; P<0.0001). This study provides the rationale and necessary details for incorporating cytogenetic findings and platelet count in future prognostic models for PMF.

Reduced-intensity conditioning followed by allogeneic hematopoietic stem cell transplantation in myelofibrosis

Hematopoietic stem cell transplantation offers a curative therapy for patients with myelofibrosis. Because of toxicity, allografting following myeloablative regimens is mainly applicable to young patients. With the introduction of dose-reduced conditioning using busulfan or melphalan with fludarabine, transplantation has become tolerable also for older patients. Implementation of antithymocyte globulin in the conditioning has resulted in effective prevention of graft-versus-host disease and an increased use of alternative donors. Through the discovery of new disease-specific mutations, close monitoring of residual disease became feasible in many patients and the outcome of posttransplant strategies improved. Still challenging is the achievement of new, transplant-derived models to estimate risk status and possible outcome for every individual patient, to help in therapeutic decision making and the determination of the optimal timing of stem cell transplantation. Such a tool may optimally include not only clinicomorphologic characteristics but also other potentially relevant factors such as cytogenetics and novel molecular markers.

Phase II study of obatoclax mesylate (GX15-070), a small-molecule BCL-2 family antagonist, for patients with myelofibrosis

BACKGROUND

Myelofibrosis (MF) is a disease characterized by the overexpression of the antiapoptotic BCL-2 family of proteins (eg, BCL-XL and MCL-1).

PATIENTS AND METHODS

We conducted a multicenter, open-label, noncomparative phase II study of obatoclax mesylate, a small-molecule pan-BCL-2 antagonist, in patients with MF. Obatoclax was administered as a 24-hour infusion (on an outpatient basis) every 2 weeks at a fixed dose of 60 mg.

RESULTS

A total of 22 patients were enrolled, with a median age of 63 years (range, 43-89 years). Twelve were men, and all 22 patients were previously treated (median of 2 previous therapies). Ten patients (45%) had a Lille score of 1, and 9 patients (41%) had a Lille score of 2. Thirteen (59%) were red blood cell transfusion dependent. A median of 7 cycles of obatoclax were administered. No patient achieved complete or partial response according to International Working Group criteria. One patient (4%) demonstrated a clinical improvement (in terms of hemoglobin and platelet count) after 7 cycles of therapy. The improvement was sustained for 4 cycles of therapy, after which he underwent allogeneic stem cell transplantation. The most common adverse events included low-grade ataxia and fatigue in 50% of the patients. Dose reduction because of toxicity was required in 1 patient, whereas 2 patients were taken off the study because of grade 3 ataxia and grade 3 heart failure. Grade 3/4 anemia and thrombocytopenia were evident in 6 (27%) and 4 (18%) patients, respectively.

CONCLUSION

Obatoclax exhibits no significant clinical activity in patients with MF at the dose and schedule evaluated.

Impact of JAK2V617F mutation status, allele burden, and clearance after allogeneic stem cell transplantation for myelofibrosis

Allogeneic stem cell transplantation (ASCT) after reduced-intensity conditioning has become a reasonable treatment option for patients with advanced myelofibrosis. The role of characteristic molecular genetic abnormalities, such as JAK2V617F on outcome of ASCT, is not yet elucidated. In 139 of 162 myelofibrosis patients with known JAK2V617F mutation status who received ASCT after reduced-intensity conditioning, the impact of JAK2 genotype, JAK2V617F allele burden, and clearance of mutation after ASCT was evaluated. Overall survival was significantly reduced in multivariate analysis in patients harboring JAK2 wild-type (hazard ratio = 2.14, P = .01) compared with JAK2 mutated patients. No significant influence on outcome was noted for the mutated allele burden analyzed either as continuous variable or after dividing into quartiles. Achievement of JAK2V617F negativity after ASCT was significantly associated with a decreased incidence of relapse (hazard ratio = 0.22, P = .04). In a landmark analysis, patients who cleared JAK2 mutation level in peripheral blood 6 months after ASCT had a significant lower risk of relapse (5% vs 35%, P = .03). We conclude that JAK2V617F-mutated status, but not allele frequency, resulted in an improved survival and rapid clearance after allografting reduces the risk of relapse.

A dynamic prognostic model to predict survival in primary myelofibrosis: a study by the IWG-MRT (International Working Group for Myeloproliferative Neoplasms Research and Treatment)

Age older than 65 years, hemoglobin level lower than 100 g/L (10 g/dL), white blood cell count greater than 25 × 109/L, peripheral blood blasts 1% or higher, and constitutional symptoms have been shown to predict poor survival in primary myelofibrosis (PMF) at diagnosis. To investigate whether the acquisition of these factors during follow-up predicts survival, we studied 525 PMF patients regularly followed. All 5 variables had a significant impact on survival when analyzed as time-dependent covariates in a multivariate Cox proportional hazard model and were included in 2 separate models, 1 for all patients (Dynamic International Prognostic Scoring System [DIPSS]) and 1 for patients younger than 65 years (age-adjusted DIPSS). Risk factors were assigned score values based on hazard ratios (HRs). Risk categories were low, intermediate-1, intermediate-2, and high in both models. Survival was estimated by the HR. When shifting to the next risk category, the HR was 4.13 for low risk, 4.61 for intermediate-1, and 2.54 for intermediate-2 according to DIPSS; 3.97 for low risk, 2.84 for intermediate-1, and 1.81 for intermediate-2 according to the age-adjusted DIPSS. The novelty of these models is the prognostic assessment of patients with PMF anytime during their clinical course, which may be useful for treatment decision-making.

Outcome of transplantation for myelofibrosis

Myelofibrosis is a myeloproliferative disorder incurable with conventional strategies. Several small series have reported long-term disease-free survival (DSF) after allogeneic hematopoietic cell transplantation (HCT). In this study, we analyze the outcomes of 289 patients receiving allogeneic transplantation for primary myelofibrosis between 1989 and 2002, from the database of the Center for International Bone Marrow Transplant Research (CIBMTR). The median age was 47 years (range: 18-73 years). Donors were HLA identical siblings in 162 patients, unrelated individuals in 101 patients, and HLA nonidentical family members in 26 patients. Patients were treated with a variety of conditioning regimens and graft-versus-host disease (GVHD) prophylaxis regimens. Splenectomy was performed in 65 patients prior to transplantation. The 100-day treatment-related mortality was 18% for HLA identical sibling transplants, 35% for unrelated transplants, and 19% for transplants from alternative related donors. Corresponding 5-year overall survival (OS) rates were 37%, 30%, and 40%, respectively. DFS rates were 33%, 27%, and 22%, respectively. DFS for patients receiving reduced-intensity transplants was comparable: 39% for HLA identical sibling donors and 17% for unrelated donors at 3 years. In this large retrospective series, allogeneic transplantation for myelofibrosis resulted in long-term relapse-free survival (RFS) in about one-third of patients.

Therapy of myelofibrosis (excluding JAK2 inhibitors)

Myelofibrosis shows a progressive clinical course and usually a poor, lethal prognosis. Allogeneic transplantation is an effective, potentially curable treatment approach although only a minority of patients may currently benefit from it. New effective treatment strategies are becoming available for this disease, including not only JAK2 inhibitors, but also other innovative drugs, targeting more general oncogenic mechanisms and the epigenetic control of cell proliferation and differentiation.

The role of allogeneic SCT in primary myelofibrosis: a British Society for Blood and Marrow Transplantation study

Fifty-one patients with primary myelofibrosis (PMF) received allogeneic haematopoietic stem cell transplants from related (n=33) or unrelated (n=18) donors. Twenty-seven patients, 19-54 years old, were prepared with myeloablative regimens including CY plus BU (n=4) or TBI (n=23). Twenty-four patients, 40-64 years old, received reduced-intensity conditioning (RIC) regimens. All RIC regimens contained fludarabine, combined with melphalan (n=19) or BU (n=5), and alemtuzumab or anti-thymocyte globulin (ATG) in the majority (n=19). Four patients (17%) in the RIC group had primary graft failure. Previous splenectomy reduced time to engraftment in the RIC group (13 versus 20 days; P=0.008). For MA and RIC groups, respectively, at 3 years, overall survival rates were 44 and 31% (P=0.67), progression-free survival 44 and 24% (P=0.87), and actuarial relapse rates 15 and 46% (P=0.06). Non-relapse mortality at 3 years was 41% for the myeloablative and 32% for the RIC group. Acute GVHD occurred in 29 and 38% of patients in the myeloablative and RIC groups, respectively. Extensive chronic GVHD developed in 30 and 35% of evaluable patients, respectively.

Cotreatment with panobinostat and JAK2 inhibitor TG101209 attenuates JAK2V617F levels and signaling and exerts synergistic cytotoxic effects against human myeloproliferative neoplastic cells

The mutant JAK2V617F tyrosine kinase (TK) is present in the majority of patients with BCR-ABL-negative myeloproliferative neoplasms (MPNs). JAK2V617F activates downstream signaling through the signal transducers and activators of transcription (STAT), RAS/mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3 (PI3)/AKT pathways, conferring proliferative and survival advantages in the MPN hematopoietic progenitor cells (HPCs). Treatment with the pan-histone deacetylase (HDAC) inhibitor panobinostat (PS) is known to inhibit the chaperone function of heat shock protein 90, as well as induce growth arrest and apoptosis of transformed HPCs. Here, we demonstrate that PS treatment depletes the autophosphorylation, expression, and downstream signaling of JAK2V617F. Treatment with PS also disrupted the chaperone association of JAK2V617F with hsp90, promoting proteasomal degradation of JAK2V617F. PS also induced apoptosis of the cultured JAK2V617F-expressing human erythroleukemia HEL92.1.7 and Ba/F3-JAK2V617F cells. Treatment with the JAK2 TK inhibitor TG101209 attenuated JAK2V617F autophosphorylation and induced apoptosis of HEL92.1.7 and Ba/F3-JAK2V617F cells. Cotreatment with PS and TG101209 further depleted JAK/STAT signaling and synergistically induced apoptosis of HEL92.1.7 and Ba/F3-JAK2V617F cells. Cotreatment with TG101209 and PS exerted greater cytotoxicity against primary CD34(+) MPN cells than normal CD34(+) HPCs. These in vitro findings suggest combination therapy with HDAC and JAK2V617F inhibitors is of potential value for the treatment of JAK2V617F-positive MPN.

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

From 2002 to 2007, 103 patients with primary myelofibrosis or postessential thrombocythemia and polycythemia vera myelofibrosis and a median age of 55 years (range, 32-68 years) were included in a prospective multicenter phase 2 trial to determine efficacy of a busulfan (10 mg/kg)/fludarabine (180 mg/m(2))-based reduced-intensity conditioning regimen followed by allogeneic stem cell transplantation from related (n = 33) or unrelated donors (n = 70). All but 2 patients (2%) showed leukocyte and platelet engraftment after a median of 18 and 22 days, respectively. Acute graft-versus-host disease grade 2 to 4 occurred in 27% and chronic graft-versus-host disease in 43% of the patients. Cumulative incidence of nonrelapse mortality at 1 year was 16% (95% confidence interval, 9%-23%) and significantly lower for patients with a completely matched donor (12% vs 38%; P = .003). The cumulative incidence of relapse at 3 years was 22% (95% confidence interval, 13%-31%) and was influenced by Lille risk profile (low, 14%; intermediate, 22%; and high, 34%; P = .02). The estimated 5-year event-free and overall survival was 51% and 67%, respectively. In a multivariate analysis, age older than 55 years (hazard ratio = 2.70; P = .02) and human leukocyte antigen-mismatched donor (hazard ratio = 3.04; P = .006) remained significant factors for survival. The study was registered at www.clinicaltrials.gov as #NCT 00599547.

Primary myelofibrosis: update on definition, pathogenesis, and treatment

Primary myelofibrosis (PMF) is a clonal stem cell disorder that manifests clinically as anemia, splenomegaly due to extramedullary hematopoiesis, leukoerythroblastosis, and constitutional symptoms, which are the clinical hallmarks of PMF. Within the past three years it has been determined that a single, recurrent, somatic mutation in the gene encoding the cytoplasmic tyrosine kinase Janus kinase 2 (JAK2) occurs in the majority of patients with PMF, and more recently, activating mutations in the gene encoding the thrombopoietin receptor MPL have also been identified in a subset of PMF patients. These discoveries have yielded important insights into the pathogenesis of PMF and have brought about the first opportunity for rationally targeted therapy for this disorder. Here we present an updated review of the pathogenesis, definition, and treatment of PMF in light of the discovery of JAK2 and MPL mutations, as well as other recent work in the myeloproliferative neoplasm field.

Epigenetic therapy in myeloproliferative neoplasms: evidence and perspectives

The classic Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), which include polycythaemia vera, essential thrombocythaemia and primary myelofibrosis, originate from a stem cell-derived clonal myeloproliferation that manifests itself with variable haematopoietic cell lineage involvement; they are characterized by a high degree of similarities and the chance to transform each to the other and to evolve into acute leukaemia. Their molecular pathogenesis has been associated with recurrent acquired mutations in janus kinase 2 (JAK2) and myeloproliferative leukemia virus oncogene (MPL). These discoveries have simplified the diagnostic approach and provided a number of clues to understanding the phenotypic expression of MPNs; furthermore, they represented a framework for developing and/or testing in clinical trials small molecules acting as tyrosine kinase inhibitors. On the other hand, evidence of abnormal epigenetic gene regulation as a mechanism potentially contributing to the pathogenesis and the phenotypic diversity of MPNs is still scanty; however, study of epigenetics in MPNs represents an active field of research. The first clinical trials with epigenetic drugs have been completed recently, whereas others are still ongoing; results have been variable and at present do not allow any firm conclusion. Novel basic and translational information concerning epigenetic gene regulation in MPNs and the perspectives for therapy will be critically addressed in this review.

Identification of patients with poorer survival in primary myelofibrosis based on the burden of JAK2V617F mutated allele

A total of 186 patients with primary myelofibrosis (PMF) were genotyped for JAK2V617F at diagnosis aimed at analyzing the correlation of mutational status and mutated allele burden with outcome variables, including time to anemia, leukocytosis, leukopenia, thrombocytopenia, massive splenomegaly, leukemia, and with overall survival. A total of 127 JAK2V617F-mutated patients (68% of whole series) were divided in quartiles of V617F allele burden. After a median follow-up of 17.2 months, 23 patients died, 15 because of leukemia. A JAK2V617F mutated status did not impact on the rate of leukemia transformation or overall survival. Patients in the lower quartile had shorter time to anemia and leukopenia and did not progress to large splenomegaly. Furthermore, survival was significantly reduced in the lower quartile compared with upper quartiles and JAK2 wild-type patients. In multivariate analysis, factors associated with reduced survival were age, a blast count more than 1%, and a JAK2V617F burden within first quartile. Causes of death in the lower quartile were represented mainly by systemic infections. We conclude that a low JAK2V617F allele burden at diagnosis is preferentially associated with a myelodepletive rather than myeloproliferative phenotype and represents an independent factor associated with shortened survival in patients with PMF.

Survival in young patients with intermediate- / high-risk myelofibrosis: estimates derived from databases for non transplant patients

Recent studies have suggested that allogenic stem cell transplantation (allo-SCT) might be a better treatment option, compared to drug therapy, for young patients with high-/intermediate-risk primary myelofibrosis (PMF). However, there are no controlled studies that validate this contention and allo-SCT is associated with a substantial risk of procedure-related mortality and morbidity. In a retrospective analysis of nontransplant PMF patients, who were both young (age <60 years) and with high-/intermediate-risk disease, 1- and 3-year survival estimates were 87% and 55%, 95% and 77%, 71% and 58%, respectively, involving patients seen at three different centers with expertise in PMF; these data did not appear to be inferior to those published in the context of either myeloablative or reduced-intensity conditioning allo-SCT. These observations underscore the need for controlled studies to accurately assess the value of allo-SCT in PMF.

From palliation to epigenetic therapy in myelofibrosis

Myelofibrosis shows a progressive clinical course and usually a poor, lethal prognosis. The molecular pathogenesis of this disease largely remains to be fully understood but the identification of the JAK2V617F mutation in more than half of patients was a major improvement in our understanding of the disease biology and may represent the first biologic marker useful for risk stratification, independently from conventional clinical predictors. After many elusive efforts, new effective treatment strategies are becoming available for this disease. Allogeneic transplantation following reduced-intensity conditioning programs, at least in some patients, may induce not only a hematologic response but also a molecular remission, thus supporting the hope of a possible, definitive eradication of the disease. Moreover, new innovative drugs, targeting either the JAK2V617F mutation or more general oncogenic mechanisms, may provide widely applicable, effective treatments to many patients for whom allogeneic transplantation is not feasible.