Single unrelated umbilical cord blood versus unmanipulated haploidentical HCT using PTCy in pediatric AML: a retrospective study on behalf of the EBMT PDWP and CTIWP.

Hematopoietic stem cell transplantation (HCT) is the standard consolidation therapy for children with high-risk or relapsed acute myeloid leukemia (AML). In the absence of an human leukocyte antigen (HLA)-matched donor, both unrelated cord blood transplantation (UCBT) and haploidentical HCT with post-transplant cyclophosphamide (haplo-PTCy) serve as viable alternatives. This study analyzed outcomes of 254 pediatric AML patients (CR1/CR2) who underwent either single-unit UCBT (N = 127) without serotherapy or haplo-PTCy (N = 127) between 2011 and 2021. Propensity score weighting was applied to minimize baseline differences. With a median follow-up of 2.9 years, no significant differences were observed in overall survival, leukemia-free survival, relapse incidence, non-relapse mortality (NRM), or graft-versus-host disease (GVHD)-free relapse-free survival. However, UCBT recipients had a lower risk of chronic GVHD (7.1% vs. 19.8%; P = 0.019). These findings confirm comparable survival outcomes between UCBT and Haplo-PTCy. Given the higher risk of cGVHD in haplo-PTCy, further research is needed to refine GVHD prevention strategies while maintaining relapse-free survival. Both approaches remain safe and readily available alternatives for pediatric AML patients lacking matched donors.