Choosing an optimal alternative donor is an important clinical concern in allogeneic hematopoietic cell transplantation (HCT). In Japan, single-unit umbilical cord blood transplantation (UCBT) has been widely used in the last two decades, whereas HCT from HLA-haploidentical related donors (haplo-HCT) has been increasingly used following the advent of posttransplant cyclophosphamide (PTCY) for graft-versus-host disease (GVHD) prophylaxis. This registry-based study aimed to compare outcomes between single-unit UCBT (n = 848) and PTCY-based haplo-HCT (n = 241) performed during first complete remission in patients with acute myeloid leukemia. UCBT was associated with a lower likelihood of engraftment (P < 0.001), a higher risk of grade 2-4 and grade 3-4 acute GVHD (P = 0.003 each), and a lower risk of extensive chronic GVHD (P = 0.048). The UCBT and haplo-HCT groups did not significantly differ in 3-year probabilities of overall survival (68% versus 69%, P = 0.686), GVHD/relapse-free survival (55% versus 54%, P = 0.866), relapse (14% versus 16%, P = 0.463), and non-relapse mortality (21% versus 19%, P = 0.403), respectively, which were confirmed with multivariate analysis. These results indicate that both procedures should be considered viable options for patients lacking a matched donor.
© 2025. The Author(s), under exclusive licence to Springer Nature Limited.