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

Allogeneic Stem Cell Transplantation Combined With Transfusion of Mesenchymal Stem Cells in Primary Myelofibrosis: A Multicenter Retrospective Study

Background

Allogeneic stem cell transplantation (allo-SCT) remains the only effective curative therapy for primary myelofibrosis. Utilization and efficacy of allo-SCT are limited by lethal complications, including engraftment failure, and acute (aGVHD) and chronic graft-versus-host disease (cGVHD). Several clinical trials have explored the use of mesenchymal stem cells (MSCs) in allo-SCT to prevent hematopoietic stem cell (HSC) engraftment failure and control GVHD.

Methods

Clinical data of 17 patients with primary myelofibrosis who underwent allo-SCT combined with ex vivo expanded MSC transfusion in four centers from February 2011 to December 2018 were retrospectively analyzed.

Results

All patients received myeloablative conditioning regimen. The median number of transplanted nucleated cells (NCs) per kilogram body weight was 11.18 × 10⁸ (range: 2.63–16.75 × 10⁸), and the median number of CD34⁺ cells was 4.72 × 10⁶ (range: 1.32–8.4 × 10⁶). MSCs were transfused on the day of transplant or on day 7 after transplant. The median MSC infusion number was 6.5 × 10⁶ (range: 0.011–65 × 10⁶). None of the patients experienced primary or secondary graft failure in the study. The median time to neutrophil engraftment was 13 days (range: 11–22 days), and the median time to platelet engraftment was 21 days (range: 12–184 days). The median follow-up time was 40.3 months (range: 1.8–127.8 months). The estimated relapse-free survival (RFS) at 5 years was 79.1%, and overall survival (OS) at 5 years was 64.7%. Analysis showed that the cumulative incidence of aGVHD grade II to IV was 36% (95% CI: 8%–55%) and that of grade III to IV was 26% (95% CI: 0%–45%) at day 100. The cumulative incidence of overall cGVHD at 2 years for the entire study population was 63% (95% CI: 26%–81%). The cumulative incidence of moderate to severe cGVHD at 2 years was 17% (95% CI: 0%–42%). Seven patients died during the study, with 5 patients succumbing from non‐relapse causes and 2 from disease relapse.

Conclusion

The findings of the study indicate that allo-SCT combined with MSC transfusion may represent an effective treatment option for primary myelofibrosis.

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.

Emerging drugs for myelofibrosis

INTRODUCTION

Myelofibrosis (MF), a Philadelphia chromosome-negative myeloproliferative neoplasm, is a life-threatening heterogeneous disorder characterized by dysregulation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling network. The clinical hallmarks of MF are progressive splenomegaly, anemia and debilitating symptoms attributable to ineffective hematopoiesis and excessive production of proinflammatory cytokines.

AREAS COVERED

This review describes the pathogenesis, clinical features and current treatment of MF, clinical data for ruxolitinib, a potent oral JAK1/JAK2 inhibitor and the only therapy approved for the treatment of MF, and agents in development for the treatment of MF. Information was derived from relevant MF articles identified in the published literature and abstracts of recent congresses.

EXPERT OPINION

Ruxolitinib reduces spleen size and alleviates MF-related symptoms, thereby improving quality of life. Ruxolitinib may increase the risk of anemia and thrombocytopenia and does not appear to reverse bone marrow fibrosis. Studies are exploring ruxolitinib dosing strategies for patients with low platelet counts and combination therapies. Several other JAK inhibitors and other agents (i.e., immunomodulators, antifibrotic agents, anti-anemia agents, mammalian target of rapamycin [mTOR] inhibitors, epigenetic modifiers, pegylated interferon-α2a) to treat various aspects of MF (i.e., to improve blood counts or forestall marrow fibrosis) are in early clinical development.

BCR-ABL1-negative chronic myeloid neoplasms: an update on management techniques

Recent discoveries concerning mutations associated with chronic myeloproliferative neoplasms have modified our understanding of the biology of these incurable diseases and guided us to the development of inhibitors active on the constitutively activated JAK-STAT pathway. Concurrently, numerous studies dealt with clinical issues; it led to a revised WHO classification; clarified the role of mutated JAK2 and leukocytosis in the pathogenesis of cardiovascular events; allowed the development of risk prognostic scores and tools for monitoring response to therapy; and resulted in completion of Phase III trials with JAK2 inhibitor in myelofibrosis. All these results hold the promise of improving patient prognostication and therapeutic approach, with the aim of efficiently preventing disease-associated complications and, hopefully, to improve the dismal survival associated with myelofibrosis. This review discusses how to manage, according to current clinical practice, the steps of diagnosis, prognostication and therapeutic choices in myeloproliferative neoplasm patients.

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.

Philadelphia-negative classical myeloproliferative neoplasms: critical concepts and management recommendations from European LeukemiaNet

We present a review of critical concepts and produce recommendations on the management of Philadelphia-negative classical myeloproliferative neoplasms, including monitoring, response definition, first- and second-line therapy, and therapy for special issues. Key questions were selected according the criterion of clinical relevance. Statements were produced using a Delphi process, and two consensus conferences involving a panel of 21 experts appointed by the European LeukemiaNet (ELN) were convened. Patients with polycythemia vera (PV) and essential thrombocythemia (ET) should be defined as high risk if age is greater than 60 years or there is a history of previous thrombosis. Risk stratification in primary myelofibrosis (PMF) should start with the International Prognostic Scoring System (IPSS) for newly diagnosed patients and dynamic IPSS for patients being seen during their disease course, with the addition of cytogenetics evaluation and transfusion status. High-risk patients with PV should be managed with phlebotomy, low-dose aspirin, and cytoreduction, with either hydroxyurea or interferon at any age. High-risk patients with ET should be managed with cytoreduction, using hydroxyurea at any age. Monitoring response in PV and ET should use the ELN clinicohematologic criteria. Corticosteroids, androgens, erythropoiesis-stimulating agents, and immunomodulators are recommended to treat anemia of PMF, whereas hydroxyurea is the first-line treatment of PMF-associated splenomegaly. Indications for splenectomy include symptomatic portal hypertension, drug-refractory painful splenomegaly, and frequent RBC transfusions. The risk of allogeneic stem-cell transplantation-related complications is justified in transplantation-eligible patients whose median survival time is expected to be less than 5 years.

Management of myelofibrosis

Myelofibrosis (MF), either primary or arising from previous polycythemia vera (PV) or essential thrombocythemia (ET), is the worst among the chronic myeloproliferative neoplasms in terms of survival and quality of life. Patients with MF have to face several clinical issues that, because of the poor effectiveness of medical therapy, surgery or radiotherapy, represent largely unmet clinical needs. Powerful risk stratification systems, applicable either at diagnosis using the International Prognostic Scoring System (IPSS) or during the variable course of illness using the Dynamic International Prognostic Scoring System (DIPSS) and DIPSS Plus, allow recognition of categories of patients with survival times ranging from decades to < 2 years. These scores are especially important for therapeutic decisions that include allogeneic stem cell transplantation (allogeneic SCT), the only curative approach that still carries a nonnegligible risk of morbidity and mortality even with newest reduced intensity conditioning (RIC) regimens. Discovery of JAK2V617F mutation prompted the development of clinical trials using JAK2 inhibitors; these agents overall have resulted in meaningful symptomatic improvement and reduction of splenomegaly that were otherwise not achievable with conventional therapy. Intriguing differences in the efficacy and tolerability of JAK2 inhibitors are being recognized, which could lead to a nonoverlapping spectrum of activity/safety. Other agents that do not directly target JAK2 and have shown symptomatic efficacy in MF are represented by inhibitors of the mammalian target of rapamycin (mTOR) and histone deacetylases (HDACs). Pomalidomide appears to be particularly active against MF-associated anemia. However, because these agents are all poorly effective in reducing the burden of mutated cells, further advancements are needed to move from enhancing our ability to palliate the disease to arriving at an actual cure for MF.

Assessing new therapies and their overall impact in myelofibrosis

Clinical management of myelofibrosis (MF)--whether primary or arising from an antecedent myeloproliferative neoplasm (post-essential thrombocythemia/polycythemia vera MF)--is currently in a period of transition that began with the discovery of the JAK2-V617F mutation 5 years ago. Selective JAK2 inhibitors have been developed, and clinical trials thus far have demonstrated that several of these agents meaningfully reduce MF-associated splenomegaly and constitutional symptoms. JAK2 inhibitors have durable benefits, act across the spectrum of MF subtypes, and provide a level of symptomatic benefit not seen with previous generations of nontargeted therapies. However, the JAK2 inhibitors can cause anemia and/or gastrointestinal disturbance, and their impact on JAK2 allele burden and the natural history is not yet fully defined. Several additional therapies that do not directly target JAK2 (eg, immunomodulatory drugs, histone deacetylase inhibitors, and inhibitors of the mammalian target of rapamycin [mTOR]) may ameliorate MF-associated anemia and morbidity-inducing symptoms. Balancing the potential benefits of these new agents against the risks and benefits of allogeneic stem cell transplantation (which can be curative, but carries a high risk of treatment-associated morbidity and mortality) requires an accurate estimation of the prognosis for an individual patient. Enhanced prognostic modeling systems are helping us to better characterize prognosis in MF patients not only at diagnosis, but also along the dynamic and variable course of the illness. Future advancements in the efficacy of MF-targeted therapy will likely arise from new pathogenetic insights and from combining JAK2 inhibitors with other agents.

Mature survival data for 176 patients younger than 60 years with primary myelofibrosis diagnosed between 1976 and 2005: evidence for survival gains in recent years

In the past 20 years, management of primary myelofibrosis (PMF) has incorporated new treatment approaches, but survival benefits have not been confirmed in controlled studies. This retrospective study includes 176 consecutive patients younger than age 60 years in whom PMF was diagnosed during a 30-year period (1976-2005). Median age at diagnosis was 50 years (range, 18-59 years), and 98 patients (55%) were men. At the time of this report, 99 patients (56%) had died; the 77 surviving patients were followed up for a median of 8 years (range, 4-24 years). Overall median survival was 9.2 years, and 15- and 20-year survival rates were 32% and 20%, respectively. According to the Dupriez Prognostic Scoring System (PSS), median survivals were 12.7, 4.8, and 2.4 years in low- (n=117), intermediate- (n=44) and high- (n=15) risk patients (P<.001). According to the International PSS, median survivals were 13.4, 9.7, 3.3, and 2.4 years in low- (n=76), intermediate-1 (n=50), intermediate-2 (n=29), and high-risk patients (n=8; P<.001). To examine the effect of decade of diagnosis on survival, we divided study patients into 3 groups by year of diagnosis: 1976-1985 (n=36), 1986-1995 (n=45), and 1996-2005 (n=95). The corresponding median survivals were 4.8, 7.3, and "not reached" (P=.003), and the difference in survival was significant during multivariable analysis that included risk scores according to the aforementioned PSSs and age as covariates. The improvement in survival in recent years was most apparent in patients with high/intermediate-risk disease (P<.002), not in those with low-risk disease (P=.42). These observations are encouraging and suggest a salutary effect from modern therapeutic approaches in PMF.

International Prognostic Scoring System-independent cytogenetic risk categorization in primary myelofibrosis

Among 200 patients with primary myelofibrosis, karyotype at diagnosis was abnormal in 83 (42%). To assess their individual prognostic impact, specific cytogenetic abnormalities with more than or equal to 5 informative cases were identified and the rest grouped separately as "other abnormalities." Median survival in patients with sole +9 (n = 6), sole 20q- (n = 21), sole 13q- (n = 8), normal karyotype (n = 117), "other abnormalities" (n = 28), complex karyotype (n = 13), and sole +8 (n = 7) were "not reached," 112, 105, 80, 46, 34, and 28 months, respectively (P = .01). Accordingly, 4 cytogenetic risk groups were considered: (1) favorable (sole +9, 20q-, or 13q-), (2) normal, (3) unfavorable (complex karyotype or sole +8), and (4) "other abnormalities." Multivariable analysis confirmed the International Prognostic Scoring System (IPSS)-independent prognostic value of both 4-way and 2-way (ie, favorable/normal vs unfavorable/other abnormalities; IPSS-adjusted hazard ratio = 0.37; 95% confidence interval, 0.24-0.58) cytogenetic risk categorization (P < .01). The ability to prognostically dissect a specific IPSS category has major therapeutic implications.