Unmanipulated Haploidentical Hematopoietic Stem Cell Transplantation in First Complete Remission Can Abrogate the Poor Outcomes of Children with Acute Myeloid Leukemia Resistant to the First Course of Induction Chemotherapy.

Allogeneic hematopoietic stem cell transplantation (HSCT) is an important therapy option for children with acute myeloid leukemia (AML) resistant to the first course of induction chemotherapy (IC1st). We aimed to identify the efficacy of unmanipulated haploidentical HSCT (haplo-HSCT) in children with AML in the first complete remission and whether children resistant (IC1st-resistant; n = 38) or sensitive (IC1st-sensitive; n = 59) to the IC1st can achieve comparable outcomes. The cumulative incidence of grades III to IV acute graft-versus-host disease (GVHD) and severe chronic GVHD was .0% versus 20.1% (P = .038) and 21.7% versus 13.2% (P = .238), respectively, for the IC1st-resistant and IC1st-sensitive groups. The 3-year cumulative incidence of relapse and nonrelapse mortality was 22.2% versus 7.6% (P = .061) and 5.3% versus 10.8% (P = .364), respectively, for the IC1st-resistant and IC1st-sensitive groups. The 3-year probability of overall survival and disease-free survival was 76.3% versus 83.0% (P = .657) and 72.5% versus 81.6% (P = .396), respectively, for the IC1st-resistant and IC1st-sensitive groups. Multivariate analysis failed to show significant differences in survival rates between the groups. Thus, our results show that unmanipulated haplo-HSCT may overcome the poor prognostic significance of IC1st-resistance in children with AML, and it is valid as a postremission treatment for children with IC1st-resistant AML lacking an HLA-matched donor.