Achievement of complete remission predicts outcome of allogeneic haematopoietic stem cell transplantation in patients with chronic myelomonocytic leukaemia. A study of the Chronic Malignancies Working Party of the European Group for Blood and Marrow Transplantation

The results of allogeneic stem cell transplantation (allo-SCT) in chronic myelomonocytic leukaemia (CMML) are usually reported together with other categories of myelodysplastic syndrome. We analysed transplantation outcome in 513 patients with CMML, with a median age of 53 years reported to the European Group for Blood and Marrow Transplantation. Conditioning was standard (n = 249) or reduced-intensity (n = 226). Donors were human leucocyte antigen-related (n = 285) or unrelated (n = 228). Disease status at transplantation was complete remission (CR) in 122 patients, no CR in 344, and unknown in 47. Engraftment was successful in 95%. Grades 2-4 acute graft-versus-host disease (GvHD) occurred in 33% of the patients and chronic GvHD was reported in 24%. The 4-year cumulative incidence of non-relapse mortality was 41% and 32% for relapse, resulting in a 4-year estimated relapse-free and overall survival (OS) of 27% and 33%, respectively. Patients transplanted in CR had lower probability for non-relapse death (P = 0·002) and longer relapse-free and OS (P = 0·001 and P = 0·005, respectively). In multivariate analysis the only significant prognostic factor for survival was the presence of CR at transplantation (P = 0·005). Allo-SCT remains a curative treatment option for patients with CMML and should preferably be performed early after diagnosis or after establishing the best possible remission status.