Dose-Reduced Versus Standard Conditioning Followed by Allogeneic Stem-Cell Transplantation for Patients With Myelodysplastic Syndrome: A Prospective Randomized Phase III Study of the EBMT (RICMAC Trial).

Purpose To compare a reduced-intensity conditioning regimen (RIC) with a myeloablative conditioning regimen (MAC) before allogeneic transplantation in patients with myelodysplastic syndrome (MDS) within a randomized trial. Patients and Methods Within the European Society of Blood and Marrow Transplantation, we conducted a prospective, multicenter, open-label, randomized phase III trial that compared a busulfan-based RIC with MAC in patients with MDS or secondary acute myeloid leukemia. A total of 129 patients were enrolled from 18 centers. Patients were randomly assigned in a 1:1 ratio and were stratified according to donor, age, and blast count. Results Engraftment was comparable between both groups. The CI of acute graft-versus-host disease II to IV was 32.3% after RIC and 37.5% after MAC ( P = .35). The CI of chronic graft-versus-host disease was 61.6% after RIC and 64.7% after MAC ( P = .76). The CI of nonrelapse mortality after 1 year was 17% (95% CI, 8% to 26%) after RIC and 25% (95% CI, 15% to 36%) after MAC ( P = .29). The CI of relapse at 2 years was 17% (95% CI, 8% to 26%) after RIC and 15% (95% CI, 6% to 24%) after MAC ( P = .6), which resulted in a 2-year relapse-free survival and overall survival of 62% (95% CI, 50% to 74%) and 76% (95% CI, 66% to 87%), respectively, after RIC, and 58% (95% CI, 46% to 71%) and 63% (95% CI, 51% to 75%), respectively, after MAC ( P = .58 and P = .08, respectively). Conclusion This prospective, randomized trial of the European Society of Blood and Marrow Transplantation provides evidence that RIC resulted in at least a 2-year relapse-free survival and overall survival similar to MAC in patients with MDS or secondary acute myeloid leukemia.