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

Characterization of engraftment dynamics in myelofibrosis after allogeneic hematopoietic cell transplantation including novel conditioning schemes

Introduction

Myelofibrosis (MF) is a rare hematopoietic stem cell disorder progressing to bone marrow (BM) failure or blast phase. Allogeneic hematopoietic cell transplantation (HCT) represents a potentially curative therapy for a limited subset of patients with advanced MF, who are eligible, but engraftment in MF vs. AML is delayed which promotes complications. As determinants of engraftment in MF are incompletely characterized, we studied engraftment dynamics at our center.

Methods

A longitudinal cohort of 71 allogeneic HCT performed 2000-2019 with >50% after 2015 was evaluated.

Results

Median time to neutrophil engraftment ≥0.5x109/l was +20 days post-transplant and associated with BM fibrosis, splenomegaly and infused CD34+ cell number. Engraftment dynamics were similar in primary vs. secondary MF and were independent of MF driver mutations in JAK2, CALR and MPL. Neutrophil engraftment occurred later upon haploidentical HCT with thiotepa-busulfan-fludarabine conditioning, post-transplant cyclophosphamide and G-CSF (TBF-PTCy/G-CSF) administered to 9.9% and 15.6% of patients in 2000-2019 and after 2015, respectively. Engraftment of platelets was similarly delayed, while reconstitution of reticulocytes was not affected.

Conclusions

Since MF is a rare hematologic malignancy, this data from a large number of HCT for MF is essential to substantiate that later neutrophil and platelet engraftment in MF relates both to host and treatment-related factors. Observations from this longitudinal cohort support that novel conditioning schemes administered also to rare entities such as MF, require detailed evaluation in larger, multi-center cohorts to assess also indicators of long-term graft function and overall outcome in patients with this infrequent hematopoietic neoplasm undergoing allogeneic transplantation.

Cardiovascular events among recipients of hematopoietic stem cell transplantation-A systematic review and meta-analysis

Cardiovascular diseases are an emerging cause of mortality and morbidity in survivors of hematopoietic stem cell transplantation (HSCT); however, the incidence of cardiovascular events (CVEs) in this population is not well described. This systematic review summarizes the evidence on the incidence of CVEs in HSCT recipients. Medline and Embase were searched from inception to December 2020. Inclusion criteria were cohort studies and phase 3 randomized controlled trials that reported CVEs among adults who underwent HSCT for hematological malignancies. After reviewing 8386 citations, 57 studies were included. The incidence of CVEs at 100 days was 0.19 (95% CI: 0.17-0.21) per 100 person-days after autologous HSCT and 0.06 (95% CI: 0.05-0.07) per 100 person-days after allogeneic HSCT. This higher incidence after autologous HSCT was driven by reports of arrhythmia from one population-based study in patients with multiple myeloma. The incidence of long-term CVEs was 3.98 (95% CI; 3.44-4.63) per 1000 person-years in survivors of autologous HSCT and 3.06 (95% CI; 2.69-3.48) per 1000 person-years in survivors of allogeneic HSCT. CVEs remain an important but under-reported cause of morbidity and mortality in recipients of HSCT. Future studies are required to better understand the incidence and risk factors for CVEs in HSCT recipients.

Innovative strategies to improve hematopoietic stem cell transplant outcomes in myelofibrosis

Myelofibrosis (MF) is a clonal myeloproliferative neoplasm characterized by inflammation, marrow fibrosis, and an inherent risk of blastic transformation. Hematopoietic allogeneic stem cell transplant is the only potentially curative therapy for this disease, however, survival gains observed for other transplant indications over the past two decades have not been realized for MF. The role of transplantation may also evolve with the use of novel targeted agents. The chronic inflammatory state associated with MF necessitates pretransplantation assessment of end-organ function. Applying the transplant methodology employed for other myeloid disorders to patients with MF fails to acknowledge differences in the underlying disease pathophysiology. Limited understanding of the causes of poor transplant outcomes in this cohort has prevented refinement of transplant eligibility criteria in MF. There is increasing evidence of heterogeneity in molecular disease grade, beyond the clinical manifestations which have traditionally guided transplant timing. Exploring the physiological consequences of disease chronicity unique to MF, acknowledging the heterogeneity in disease grade, and using advanced prognostic models, molecular diagnostics and other organ function diagnostic tools, we present an innovative review of strategies with the potential to improve transplant outcomes in this disease. Larger, prospective studies which consider the impact of molecular-based disease grade are needed for MF transplantation.

Allogeneic haematopoietic cell transplantation for myelofibrosis: a real-life perspective

Myelofibrosis (MF) is a clonal stem cell neoplasm with heterogeneous clinical phenotypes and well-established molecular drivers. Allogeneic haematopoietic stem cell transplantation (HSCT) offers an important curative treatment option for primary MF and post-essential thrombocythaemia/polycythaemia vera MF or secondary MF. With a disease course that varies from indolent to highly progressive, we are now able to stratify risk of mortality through various tools including patient-related clinical characteristics as well as molecular genetic profile. Owing to the high risk of mortality and morbidity associated with HSCT for patients with myelofibrosis, it is important to improve patient selection for transplant. Our primary goal is to comprehensively define our understanding of current practices including the role of Janus Kinase (JAK) inhibitors, to present the data behind transplantation before and after leukaemic transformation, and to introduce novel personalization of MF treatment with a proposed clinical-molecular prognostic model to help elucidate a timepoint optimal for consideration of HSCT.

Application of Stem Cell Therapy in Myelofibrosis

Myelofibrosis (MF) belongs to a group of clonal stem cell disorders known as the BCR-ABL-negative myeloproliferative neoplasms. Allogeneic hematopoietic stem cell transplantation (HCT) is currently the only curative treatment option for MF. Because HCT can be associated with significant morbidity and mortality, patients need to be carefully selected based on disease-risk, fitness, and transplant factors. Furthermore, in the era of JAK inhibitors, the timing of transplantation has become a challenging question. Here the authors review recent developments in HCT for MF, focusing on risk stratification and optimal timing.

Outcome of Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Myelodysplastic/Myeloproliferative Neoplasms-Unclassifiable: A Retrospective Nationwide Study of the Japan Society for Hematopoietic Cell Transplantation

To date, there are no data focusing on outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with myelodysplastic/myeloproliferative neoplasms, unclassifiable (MDS/MPN-U). This study aimed to evaluate outcomes and prognostic factors in patients with MDS/MPN-U after allo-HSCT using Japanese nationwide registry data. The primary endpoint was 3-year overall survival (OS); secondary endpoints included the cumulative incidence of relapse and nonrelapse mortality (NRM). We evaluated the prognostic factors for 3-year OS by univariate analysis using the log-rank test. In our cohort of 86 patients with MDS/MPN-U, we found a 3-year OS of 48.5%, cumulative incidence of relapse of 23.7%, and NRM of 26.3%. The 3-year OS was significantly worse in patients age ≥50 years compared with those age <50 years (38.1% versus 65.0%; P = .049) and in patients with disease progression compared with those without disease progression (28.4% versus 57.2%; P = .042). Our results suggest that allo-HSCT may offer a curative option for patients with MDS/MPN-U, and that age and disease status could be important indicators in helping clinicians determine treatment options for these patients.

Clinical Trial Simulation To Optimize Trial Design for Fludarabine Dosing Strategies in Allogeneic Hematopoietic Cell Transplantation

Optimal fludarabine exposure has been associated with improved treatment outcome in allogeneic hematopoietic cell transplantation, suggesting potential benefit of individualized dosing. A randomized controlled trial (RCT) comparing alternative fludarabine dosing strategies to current practice may be warranted, but should be sufficiently powered for a relevant end point, while still feasible to enroll. To find the optimal design, we simulated RCTs comparing current practice (160 mg/m² ) to either covariate-based or therapeutic drug monitoring (TDM)-guided dosing with potential outcomes being nonrelapse mortality (NRM), graft failure, or relapse, and ultimately overall survival (covering all three aforementioned outcomes). The inclusion in each treatment arm (n) required to achieve 80% power was calculated for all combinations of end points and dosing comparisons. The trial requiring the lowest n for sufficient power compared TDM-guided dosing to current practice with NRM as primary outcome (n = 70, NRM decreasing from 21% to 5.7%). We conclude that a superiority trial is feasible.

Allogeneic hematopoietic stem-cell transplantation for myelofibrosis

Myelofibrosis is one of the Philadelphia chromosome (Ph)-negative myeloproliferative neoplasms with heterogeneous clinical course. Though many treatment options, including Janus kinase (JAK) inhibitors, have provided clinical benefits and improved survival, allogeneic hematopoietic stem-cell transplantation (AHSCT) remains the only potentially curative therapy. Considering the significant transplant-related morbidity and mortality, it is crucial to decide who to proceed to AHSCT, and when. In this review, we discuss recent updates in patient selection, prior splenectomy, conditioning regimen, donor type, molecular mutation, and other factors affecting AHSCT outcomes. Relapse is a major cause of treatment failure; we also describe recent data on minimal residual disease monitoring and management of relapse. In addition, emerging studies have reported pretransplant therapy with ruxolitinib for myelofibrosis showing favorable results, and further research is needed to explore its use in the post-transplant setting.

Allogeneic Hematopoietic Stem Cell Transplantation for Post-essential Thrombocythemia and Post-polycythemia Vera Myelofibrosis

Objective Little information is available about the outcome of allogeneic hematopoietic stem cell transplantation (HSCT) for patients with secondary myelofibrosis from essential thrombocythemia (ET) and polycythemia vera (PV). A nationwide retrospective study of the outcome of HSCT for post-ET and post-PV myelofibrosis was conducted in Japan. Patients and Methods Clinical data for patients with post-ET (n=29) and post-PV (n=9) myelofibrosis who had received first allogeneic HSCT were extracted from the Transplant Registry Unified Management Program, which is a registry of the outcomes of HSCT in Japan. Results Five patients died without neutrophil recovery within 60 days after transplantation. The incidence of neutrophil recovery was significantly lower in umbilical cord blood (UCB) transplantation than in related donor transplantation (40% vs. 92%, p=0.010). The 1-year non-relapse mortality for post-ET and post-PV myelofibrosis was 35% and 27%, respectively (p=0.972). No patient or transplantation characteristics were associated with non-relapse mortality. The 4-year overall survival for post-ET and post-PV myelofibrosis was 46% and 65%, respectively (p=0.362). A univariate analysis identified UCB transplantation (vs. related donor, p=0.017) and ≥10 times red blood cell transfusions before transplantation (vs. <10 times, p=0.037) as predictive of a lower overall survival. Conclusion Allogeneic HSCT provides a long-term survival for at least some patients with post-ET and post-PV myelofibrosis. Further studies with more patients are required to determine the best alternative donor.

Myelofibrosis: best practices, controversies and 2019 update

Introduction: Recent advances in the prognostic scheme and treatment of primary and secondary myelofibrosis (MF) have resulted in an overwhelming amount of clinical information to assimilate. The authors believe a comprehensive review that summarizes the most recent published literature, could serve as guidelines for the practicing hematologist.Areas covered: The authors provide a summary of landmark articles regarding epidemiology, symptoms, and pathogenesis of disease. The authors conducted a systematic literature review to answer questions regarding differences between primary myelofibrosis (PMF) and secondary myelofibrosis (SMF), appropriate use and selection of the current risk-stratification models, early versus late treatment of MF and current practices in allogeneic hematopoietic stem cell transplantation (allo-HCT) for MF. The authors conclude the article with their clinical opinion based on their experience and literature review. The purpose of this article is to identify current practices, address any variation, identify and investigate conflicting results and produce statements to guide decision-making.Expert opinion: In this section, the authors advocate for and provide examples of a standardized way of incorporating future discoveries in the pathogenesis and risk-stratification models of MF. They also discuss the importance of using only one risk-stratification model for PMF and one for SMF and their reasoning for early instead of late treatment of MF.

Comparison of Outcomes of Allogeneic Transplantation for Primary Myelofibrosis among Hematopoietic Stem Cell Source Groups

The choice of alternative donor is a major issue in allogeneic hematopoietic stem cell transplantation (HSCT) for patients with primary myelofibrosis (PMF) without an HLA-matched related donor. We conducted this retrospective study using the Japanese national registry data for 224 PMF patients to compare the outcomes of first allogeneic HSCT from HLA-matched related donor bone marrow (Rtd-BM), HLA-matched related donor peripheral blood stem cells (Rtd-PB), HLA-matched unrelated donor bone marrow (UR-BM), unrelated umbilical cord blood (UR-UCB), and other hematopoietic stem cell grafts. Nonrelapse mortality (NRM) rates at 1 year after Rtd-BM, Rtd-PB, UR-BM, UR-UCB, and other transplantations were 16%, 36%, 30%, 41%, and 48%, respectively. Multivariate analysis identified UR-UCB transplantation, other transplantation, frequent RBC transfusion before transplantation, and frequent platelet (PLT) transfusion before transplantation as predictive of higher NRM. Relapse rates at 1 year after Rtd-BM, Rtd-PB, UR-BM, UR-UCB, and other transplantation were 14%, 17%, 11%, 14%, and 15%, respectively. No specific factor was associated with the incidence of relapse. Overall survival (OS) at 1 and 4 years after Rtd-BM, Rtd-PB, UR-BM, UR-UCB, and other transplantation were 81% and 71%, 58% and 52%, 61% and 46%, 48% and 27%, and 48% and 41%, respectively. Multivariate analysis identified older patient age, frequent RBC transfusion before transplantation, and frequent PLT transfusion before transplantation as predictive of lower OS. In conclusion, UR-UCB transplantation, as well as UR-BM transplantation, can be selected for PMF patients without an HLA-identical related donor. However, careful management is required for patients after UR-UCB transplantation because of the high NRM. Further studies including more patients after HLA-haploidentical related donor and HLA-mismatched unrelated donor transplantation would provide more valuable information for patients with PMF when making decisions regarding the choice of alternative donor.

Family Mismatched Allogeneic Stem Cell Transplantation for Myelofibrosis: Report from the Chronic Malignancies Working Party of European Society for Blood and Marrow Transplantation

This analysis included 56 myelofibrosis (MF) patients transplanted from family mismatched donor between 2009 and 2015 enrolled in the European Society for Blood and Marrow Transplantation database. The median age was 57years (range, 38 to 72); 75% had primary MF and 25% had secondary MF. JAK2 V617F was mutated in 61%. Donors were HLA mismatched at 2 or more loci. Stem cells were sourced from bone marrow in 66% and peripheral blood in 34%. The median CD34⁺ cell dose was 4.8 × 10⁶/kg (range, 1.7 to 22.9; n = 43). Conditioning was predominantly myeloablative in 70% and reduced intensity in the remainder. Regimens were heterogeneous with thiotepa, busulfan, fludarabine, and post-transplant cyclophosphamide used in 59%. The incidence of neutrophil engraftment by 28days was 82% (range, 70% to 93%), at a median of 21days (range, 19 to 23). At 2years the cumulative incidence of primary graft failure was 9% (95% CI 1% to 16%) and secondary graft failure was 13% (95% CI 4% to 22%). The cumulative incidence of acute graft-versus-host disease (GVHD) grades II to IV and III to IV was 28% (95% CI 16% to 40%) and 9% (95% CI 2% to 17%) at 100days. The cumulative incidence of chronic GVHD at 1 year was 45% (95% CI 32% to 58%), but the cumulative incidence of death without chronic GVHD by 1 year was 20% (95% CI 10% to 31%). With a median follow-up of 32 months, the 1- and 2-year overall survival was 61% (95% CI 48% to 74%) and 56% (95% CI 41% to 70%), respectively. The 1- and 2- year progression-free survival was 58% (95% CI 45% to 71%) and 43% (95% CI 28% to 58%), respectively, with a 2-year cumulative incidence of relapse of 19% (95% CI 7% to 31%). The 2-year nonrelapse mortality was 38% (95% CI 24% to 51%). This retrospective study of MF allo-SCT using family mismatched donors demonstrated feasibility of the approach, timely neutrophil engraftment in over 80% of cases, and acceptable overall and progression-free survival rates with relapse rates not dissimilar to the unrelated donor setting. However, strategies to minimize the risk of graft failure and the relatively high nonrelapse mortality need to be used, ideally in a multicenter prospective fashion.

Hematopoietic Cell Transplantation for Acute Panmyelosis with Myelofibrosis: A Retrospective Study in Japan

Acute panmyelosis with myelofibrosis (APMF) is a rare subtype of acute myeloid leukemia characterized by acute onset of cytopenias and bone marrow fibrosis in the absence of splenomegaly. Because the prognosis of APMF is extremely poor even after chemotherapy, hematopoietic cell transplantation (HCT) has been used to treat APMF. However, the outcome after HCT for APMF remains unclear. To evaluate the outcomes and prognostic factors after HCT as a therapeutic modality for APMF, we retrospectively analyzed the Japanese registration data of 40 APMF patients who received allogeneic and syngeneic HCT between 2005 and 2015. The median age at HCT was 53.5 years (range, 16 to 70). The disease status at HCT was first complete remission (CR1) in 13 patients (33%). The probability of overall survival and the cumulative incidence of relapse at 3 years were 24% and 59%, respectively. Univariate analysis identified that female sex and disease status CR1 at the time of HCT were significantly associated with higher overall survival. Although APMF patients have a poor long-term prognosis even after syngeneic and allogeneic HCT, these data suggested that allogeneic HCT offered a curative option for APMF.

Myelofibrosis: to transplant or not to transplant?

Hematopoietic cell transplantation (HCT) is the only curative therapeutic modality for myelofibrosis (MF) at present. The optimal timing of HCT is not known in the presence of wider availability of less risky nontransplant therapies such as JAK 1/2 inhibitors. Careful review of patient, disease, and transplant-related factors is required in the appropriate selection of HCT vs the best available nontransplant therapies. We highlight some of the relevant issues and positioning of HCT in light of evolving data on JAK 1/2 inhibitors. The goal of this study is to provide the reader with updated evidence of HCT for MF, recognizing that knowledge in this area is limited by the absence of comparative studies between HCT and nontransplant therapies. Prospective studies are needed for better information on: the determination of optimal timing and conditioning regimens, the best way to integrate JAK inhibitors in the HCT protocols, and the impact of JAK inhibitors on graft-versus-host disease.

Clinical features and outcomes of patients with primary myelofibrosis in Japan: report of a 17-year nationwide survey by the Idiopathic Disorders of Hematopoietic Organs Research Committee of Japan

We conducted a 17-year nationwide survey (1999-2015) to elucidate the clinical outcomes of patients with primary myelofibrosis (PMF) in Japan. Questionnaires were sent annually to approximately 500 hematology departments. Newly diagnosed patients with PMF were enrolled in this study, and were followed up annually to collect prognostic information. Approximately 50 patients were enrolled per year, yielding a total of 780 patients with PMF included in this study. The median age at diagnosis was 66 years. At the time of analysis, the median survival duration was 47 months, and the 3-year overall survival rate was 59 %. Infection and disease transformation into acute leukemia were the most frequent causes of death. Of the proposed prognostic models for predicting the outcomes of PMF patients in Japan, the Dynamic International Prognostic Scoring System of PMF plus model was the most feasible. Forty-three patients received allogeneic hematopoietic stem cell transplantation (alloSCT) at a median of 343 days after diagnosis. This treatment significantly prolonged the survival of PMF patients, and the 3-year overall survival rate after first alloSCT was 84 %. A long-term registration study is required for further evaluation of prognosis and the impact of treatments on survival.

Allogeneic Hematopoietic Cell Transplantation for Leukemic Transformation Preceded by Philadelphia Chromosome-Negative Myeloproliferative Neoplasms: A Nationwide Survey by the Adult Acute Myeloid Leukemia Working Group of the Japan Society for Hematopoietic Cell Transplantation

To clarify the outcome of allogeneic hematopoietic cell transplantation (HCT) for leukemic transformation (LT) preceded by Philadelphia chromosome-negative (Ph-neg) myeloproliferative neoplasms (MPNs), we conducted a retrospective study using the national registry database of the Japan Society for Hematopoietic Cell Transplantation. From 2000 to 2013, 39 patients underwent their first allogeneic HCT with related bone marrow or peripheral blood stem cells (n = 8), unrelated bone marrow (n = 15), and unrelated umbilical cord blood (n = 16). The median patient age was 57 years. The underlying Ph-neg MPNs included 21 cases of essential thrombocythemia, 11 cases of primary myelofibrosis, and 7 cases of polycythemia vera. The median interval between the diagnosis of LT and transplantation was 134 days. Thirty-two cases (82%) were not in remission at the time of transplantation. The 2-year overall survival rate was 29.2% (95% confidence interval [CI], 15.5% to 44.3%). The median follow-up of the surviving patients was 1989.5 days (range, 285 to 3270). The cumulative incidences of relapse and nonrelapse mortality at 2 years were 34.4% (95% CI, 19.6% to 49.8%) and 34.2% (95% CI, 19.6% to 49.4%), respectively. The study results suggested that allogeneic HCT provides long-term survival in approximately one-third of patients with LT preceded by Ph-neg MPNs.

Allogeneic Hematopoietic Stem-Cell Transplantation for Myelofibrosis: A Practical Review

Myelofibrosis is a myeloproliferative neoplasm with cardinal features of extramedullary hematopoiesis, hepatosplenomegaly, cytopenias, and constitutional symptoms that result in shortened survival and leukemic transformation. It is a disease predominantly of the elderly, and currently available therapies only offer symptom control without curative benefit or ability to alter disease progression. Allogeneic hematopoietic stem-cell transplant (HSCT) is the only potentially curative intervention; however, this is only feasible in younger and medically fit patients and selectively offered to those with high-risk disease. Despite ongoing advancements, HSCT is associated with substantial morbidity and mortality, and the determination of which patients with myelofibrosis are ideal candidates and the selection of the opportune moment to proceed with transplantation remains challenging. This review summarizes our current recommendations for the role of and indications for HSCT in myelofibrosis.

Allogeneic hematopoietic cell transplantation in patients with myelofibrosis: A single center experience

Myelofibrosis (MF) is a rare disease responsible for an increasing ineffective hematopoesis by a progressive fibrosing process in the bone marrow. The only curative treatment option is allogeneic hematopoietic cell transplantation (HCT). In this single-center analysis, we evaluated retrospectively 54 consecutive patients suffering from primary or secondary MF which underwent HCT from 1997 to 2014 after either myeloablative (MAC, n = 19) or reduced-intensity conditioning (RIC, n = 35). Overall survival (OS) and disease-free survival (DFS) after 3 years was 54/53 % for RIC versus 63/58 % for MAC (p = 0.8/0.97). Cumulative incidence of relapse was 34 % after RIC and 8 % after MAC (p = 0.16). Three-year non-relapse mortality (NRM) was 15 % after RIC and 34 % after MAC (p = 0.29). We found that RIC was associated with a lower incidence of acute graft versus host disease (GvHD; II-IV 26 vs. 0 %, p = 0.004). Evaluation of prognostic relevance of the Dynamic International Prognostic Scoring System (DIPSS) score showed a significant better OS in patient with risk score ≤3 versus >3 (after 3 years, 71 vs. 39 %, p = 0.008). While similar OS and DFS were observed with MAC or RIC, the use of RIC resulted in lower incidence of acute GvHD. RIC regimens may be therefore the preferred conditioning approach for allogeneic HCT in patients with MF.

Allogeneic hematopoietic stem cell transplantation for myelofibrosis and chronic myelomonocytic leukemia

The efficacy of hematopoietic stem cell transplantation (HSCT) is not well established in Philadelphia chromosome negative myeloproliferative neoplasms (Ph- MPNs). Without randomized prospective trials comparing HSCT to non-HSCT options or comparing HSCT regimens, physicians must rely on prognostic scoring systems and clinical experience when making decisions about who and when to transplant patients with Ph- MPNs. These patients are vulnerable to hepatic toxicity and graft failure after HSCT because of their increased likelihood of portal hypertension, massive splenomegaly, and extensive bone marrow fibrosis related to their disease. In this review, we aim to outline the indications and modalities of HSCT as they pertain to the Ph- MPNs and CMML based on the currently available evidence. We will further highlight the challenges of HSCT in these diseases, including but not limited to the incorporation of JAK inhibitors into HSCT for myelofibrosis.

Effect of conditioning regimens on graft failure in myelofibrosis: a retrospective analysis

In myelofibrosis, the introduction of reduced-intensity conditioning (RIC) preceding allogeneic stem cell transplantation (SCT) resulted in lower transplant-related mortality rates compared with myeloablative conditioning. However, lowering the intensity of conditioning may increase the risk of graft failure in myelofibrosis, although hitherto this has not been indisputably proven. We here report the outcome of 53 patients who underwent allogeneic SCT with different conditioning regimens (RIC and non-myeloablative (NMA)) in three transplantation centers in the Netherlands. The cumulative incidence of graft failure within 60 days after SCT was high (28%), and this was primarily associated with the intensity of the conditioning regimen. Cumulative neutrophil engraftment at 60 days was lower in patients who received NMA conditioning compared with those who received RIC (56% vs 84%, P=0.03). Furthermore, of six patients who received a second transplantation after graft failure, the three patients with RIC regimens subsequently engrafted, whereas the three patients who received a second NMA regimen did not. This study indicates that in myelofibrosis, NMA regimens result in high engraftment failure rates. We propose the use of more intensive conditioning regimens, incorporating busulfan or melphalan.

Controversies and dilemmas in allogeneic transplantation for myelofibrosis

JAK1/2 inhibitors have broadened the therapeutic options in myelofibrosis. Though not curative, they result in a meaningful clinical benefit with relatively fewer side effects. In contrast, allogeneic hematopoietic cell transplantation (HCT) is a potentially curative option, but is associated with significant morbidity and mortality. Hence, an important question is the optimal timing of HCT in the era of JAK inhibitors. Timing of HCT is a crucial decision, and need to be individualized based on the personal preferences and goals of therapy; in addition to patient, disease, and transplant related factors. Risk stratification by the currently established prognostic scoring systems need to be further refined by incorporation of prognostically significant mutations to guide the treatment choices better. Data on use of JAK inhibitors prior to HCT have just started to emerge. We discuss some of the current controversies and dilemmas in transplantation for myelofibrosis based on a few real life scenarios.

Unrelated cord blood transplantation for patients with primary or secondary myelofibrosis

To determine whether umbilical cord blood transplantation (UCBT) is an alternative cure for myelofibrosis (MF), we evaluated 35 UCBTs reported to Eurocord. Seven patients had secondary acute myeloid leukemia (AML) at UCBT, and median age at UCBT was 54 years. Twenty-four patients received a reduced-intensity conditioning (RIC) regimen, and 17 of 35 patients received total body irradiation (2 to 12 Gy)-fludarabine-cyclophosphamide (TCF) conditioning. The median follow-up was 24 months. The cumulative incidence of neutrophil recovery at 60 days was 80%. Fifteen patients relapsed after UCBT. The 2-year overall survival and event-free-survival (EFS) rates were 44% and 30%, respectively. All patients given TCF achieved neutrophil and platelet recovery, and the use of TCF was associated with superior EFS in the RIC population (44% versus 0%, P = .001). Patients with transformation to AML had similar outcomes to patients with less advanced stages. In conclusion, despite graft failure remaining a major concern, the role of UCBT in the management of MF, especially using RIC TCF-based regimens, deserves further investigation to improve results.