Peripheral Blood versus Bone Marrow from Unrelated Donors: Bone Marrow Allografts Have Improved Long-Term Overall and Graft-versus-Host Disease-Free, Relapse-Free Survival

Peripheral blood (PB) and bone marrow (BM) from unrelated donors can serve as a graft source for hematopoietic cell transplantation (HCT). Currently, PB is most commonly used in roughly 80% of adult recipients. Determining the long-term impact of graft source on outcomes would inform this decision. Data collected by the Center for International Blood and Marrow Transplant Research from 5200 adult recipients of a first HCT from an 8/8 or 7/8 HLA antigen-matched unrelated donor for treatment of acute leukemia, chronic myelogenous leukemia, or myelodysplastic syndrome between 2001 and 2011 were analyzed to determine the impact of graft source on graft-versus-host disease (GVHD) relapse-free survival (GRFS), defined as freedom from grade III/IV acute GVHD, chronic GVHD requiring immunosuppressive therapy, relapse, and death, and overall survival. GRFS at 2 years was superior in BM recipients compared with PB recipients (16%; 95% confidence interval [CI], 14% to 18% versus 10%; 95% CI, 8% to 11%; P <.0001) in the 8/8 HLA-matched cohort and 7/8 HLA-matched cohort (11%; 95% CI, 8% to 14% versus 5%; 95% CI, 4% to 7%; P =.001). With 8/8 HLA-matched unrelated donors, overall survival at 5 years was superior in recipients of BM (43%; 95% CI, 40% to 46% versus 38%; 95% CI, 36% to 40%; P =.014). The inferior 5-year survival in the PB cohort was attributable to a higher frequency of deaths while in remission compared with the BM cohort. For recipients of 7/8 HLA-matched grafts, survival at 5 years was similar in BM recipients and PB recipients (32% versus 29%; P =.329). BM grafts are associated with improved long-term GRFS and overall survival in recipients of matched unrelated donor HCT and should be considered the unrelated allograft of choice, when available, for adults with acute leukemia, chronic myelogenous leukemia, and myelodysplastic syndrome.