Outcomes of reduced-intensity transplantation for chronic myeloid leukemia: an analysis of prognostic factors from the Chronic Leukemia Working Party of the EBMT.

This study reports outcomes of allogeneic hematopoietic stem cell transplantation with reduced-intensity conditioning (RIC) in 186 patients with chronic myeloid leukemia (CML) from the European Group for Blood and Marrow Transplantation (EBMT). The median age was 50 years, and 64% were in first chronic phase (CP1), CP2 13%, accelerated phase 17%, and blast crises 6%. The median EBMT transplant score was 3. The day 100 transplantation-related mortality (TRM) was 6.1% (confidence interval [CI], 3.4%-11%) but rose to 23.3% (CI, 14%-27%) at 2 years. Fludarabine, busulfan, and antithymocyte globulin (Fd/Bu/ATG) was associated with the lowest TRM of 11.6% (CI, 4.7%-11%) at 1 year. Acute graft-versus-host disease (GvHD) grade II to IV occurred in 32% and chronic GvHD in 43% (extensive in 24%). ATG was associated with a lower incidence of chronic GvHD (cGvHD). The overall survival (OS) and progression-free survival (PFS) at 3 years were 58% (CI, 50%-66%) and 37% (CI, 30%-45%), respectively. Adverse OS was associated with advanced disease (relative risk [RR], 3.4). PFS was inferior in advanced disease (RR, 2.7) and a trend to improved outcomes with Fd/Bu/ATG (RR, 0.58). RIC allografts are feasible in CML in first or second CP. Since no other RIC regimen demonstrated superiority, Fd/Bu/ATG should be considered as baseline in future prospective trials.