Comparison of Donor Sources in Hematopoietic Stem Cell Transplantation for Childhood Acute Leukemia: A Nationwide Retrospective Study

•Outcomes for both unrelated bone marrow transplantation and unrelated cord blood transplantation are currently not statistically inferior to those of identical related bone marrow transplantation•Unrelated cord blood transplantation is useful option for patients with clinical urgent situations•New strategies are needed to reduce early transplantation-related mortality after unrelated cord blood transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the best therapeutic option for childhood high-risk acute leukemia. However, which donor source is optimal for children lacking an identical sibling remains unclear. To evaluate the clinical impact of donor source on allo-HSCT in childhood acute leukemia, we analyzed data from 577 children who underwent allo-HSCT after a myeloablative regimen during first or second complete remission from 2005 to 2012, using registry data of the Japan Society for Hematopoietic Cell Transplantation, and we compared outcomes of 7/8 to 8/8 HLA allelic-matched unrelated bone marrow transplantation (UR-BMT, n = 218) and 4/6 to 6/6 HLA allelic-matched unrelated cord blood transplantation (UR-CBT, n = 200) to those of HLA-identical related bone marrow transplantation (ID-BMT, n = 159). The median follow-up of survivors was 40.0 months. Three-year overall survival (OS) and leukemia-free survival (LFS) rates for ID-BMT, UR-BMT, and UR-CBT were 74.8% and 69.0%, 75.0% and 69.6%, and 71.8% and 63.8%, respectively. The multivariate analysis demonstrated that OS and LFS for the 3 groups are comparable, although UR-CBT carries a greater risk of nonrelapse mortality (hazard ratio, 2.20; P = .03, compared to ID-BMT) in the myeloablative setting for childhood high-risk acute leukemia.