Cord blood versus matched related donor transplantation in AML not in remission: role of pre-engraftment immune reactions.

Although HLA-matched related donor transplantation (MRDT) is considered the preferred graft source when available, cord blood transplantation (CBT) is an alternative source, with several studies suggesting a potent graft-versus-leukemia effect. We compared outcomes between CBT and MRDT in acute myeloid leukemia (AML) not in remission and examined how pre-engraftment immune reaction (PIR), graft-versus-host disease (GVHD), and HLA mismatch affect CBT outcomes. We retrospectively analyzed 334 patients with AML not in remission who underwent first allo-HSCT using either single-unit CBT (n = 309) or MRDT (n = 25). At 5 years, CBT recipients showed significantly better leukemia-free survival (LFS) (42.0% vs. 17.6%) and lower relapse rates (24.6% vs. 54.0%), with no difference in NRM. Among CBT recipients, patients who developed mild PIR had a lower relapse rate compared with those without PIR (hazard ratio [HR], 0.48). In contrast, severe PIR was associated with higher NRM (HR, 3.13) and worse overall survival (HR, 2.12). Acute GVHD, chronic GVHD, and HLA disparity were not significantly associated with relapse. CBT was associated with superior LFS compared with MRDT in patients with AML not in remission, and PIR occurrence and severity were associated with CBT outcomes.