Outcome of Allogeneic Stem Cell Transplantation for Patients with Chronic Myelofibrosis and Blastic Transformation of Myelofibrosis

Abstract 4534

Myelofibrosis is a clonal myeloproliferative disorder, characterized by ineffective hematopoesis and bone marrow fibrosis. The disease can present de novo or secondary to an antecedent chronic myeloproliferative neoplasm such as essential thrombocythemia (ET) or polycythemia vera (PV). Allogeneic hematopoetic stem cell transplantation (AHSCT) is a curative approach for myelofibrosis, and produces durable donor engraftment and regression of myelofibrosis in approximately 50% of eligible patients. We retrospectively evaluated 31 consecutive patients that were treated for MF with AHSCT at our institution between 1998 and 2011. Thirty-one patients, 33 to 70 years of age, with a median age of 47, males 17 and females 14 with primary myelofibrosis or myelofibrosis evolving from antecedent polycythemia vera 4 (12%) or essential thrombocythemia 10 (32%) received AHSCT. Seven (22%) patients had transformed to acute myeloid leukemia prior to transplant. JAK 2 V617F was present in 15 patients, 9 patients were JAK 2 wild type, 5 patients were not tested and 2 were unknown. Patients received AHSCT from related (n= 11) or unrelated (n= 20) donors. Fourteen patients (45%) had a normal karyotype, 16 patients (51%) had an abnormal karyotype and one was unknown. Twenty eight patients received reduced intensity conditioning regimen and three received a fully ablative transplant. The source of stem cells was marrow in 4 patients and peripheral blood in 27 patients. Median time to neutrophil engraftment was 13 days in 28 patients (90%) and three patients had primary graft failure and were re-transplanted. One of the patients receiving a second AHSCT is alive and in complete hematological remission 19 months post-transplant.Twenty-eight patients showed 95–100% donor chimerism at day 30. Two patients had mixed chimerism at day 90. Twenty-six patients (83%) survive more than 100 days, 3 patients died (10%) from relapsed/progressive disease, and 5 (16%) from TRM. However at a median follow up of 31 months post-transplant 15 patients (48%)survived, 11 (45%)with chronic myelofibrosis, and 4 out of 7(57%)who had transformed to AML prior to transplant. Of note all five patients who were greater than 65 years of age at the time of transplant engrafted and enjoyed full hematological and clinical remission, one of these individuals subsequently died of a solid tumor. In addition, one of the patients with AML had an extramedullary relapsed 36 months post-transplant. One of the unanticipated complications observed in these patients who underwent AHSCT was massive peripheral edema in some cases anasarca of unclear etiology that required diuresis and albumin infusions and that occasionally preceded the date of engraftment and persisted for several weeks after engraftment.

We conclude that AHSCT is an important therapeutic modality for not only PMF patients <65 years of age but also high risk patients > 65 years of age and individuals with blastic transformation of MF.