Allogeneic Hematopoietic Cell Transplantation for Chronic Myelofibrosis in Australia and New Zealand: Older Recipients Receiving Myeloablative Conditioning at Increased Mortality Risk

Abstract

This retrospective registry analysis examined predictive factors for outcome in 57 patients who underwent allogeneic or syngeneic hematopoietic cell transplantation (HCT) for chronic myelofibrosis (CM), either primary (n = 49) or following an antecedent condition (n = 8), reported to the Australasian Bone Marrow Transplant Registry (ABMTRR) between 1993 and 2005. During the 6 years 2000 to 2005, 40 HCTs were performed for CM compared with 17 in the 7 years 1993 to 1999. Twenty-four recipients (42%) were age 50 or over at transplantation; all of these patients were transplanted after 1997, and 15 were given reduced intensity conditioning (RIC) pretransplantation. The cumulative incidence of transplantation-related mortality was 18% at 100 days and 25% at 1 year posttransplantation. Up to 1 year posttransplantation 16 patients died, with the most common causes being infection (n = 6) and graft-versus-host disease (GVHD) (n = 5). A total of 27 patients survived for 3years or longer posttransplantation. None of these patients required regular red blood cell transfusions, and of the 17 who had not had splenectomies, none had detectable splenomegaly. Twelve patients had no detectable bone marrow fibrosis, 7 had grade 1 fibrosis, and in 8 patients no information was available. The overall survival (OS) probability for all patients was 72% at 1 year and 58% at 5years posttransplantation. Patients age 50 and over who received myeloablative conditioning fared poorly, with 1-year overall actuarial survival of 44% compared with 77% for all other patients (P = .007). In multivariate analysis, age 50 years and over at transplantation was the only significant independent unfavorable risk factor for survival post-HCT (hazard ratio 2.71, 95% confidence interval 1.16-6.34, P = .02). This study shows a clear increase in annual numbers of allogeneic HCT performed for CM in Australia and New Zealand in recent years. Five-year survival was favorable compared with international studies, but for older recipients who received myeloablative conditioning, mortality risk was elevated.