Allogeneic Hematopoietic Stem Cell Transplantation with Myeloablative Conditioning Is Associated with Favorable Outcomes in Mixed Phenotype Acute Leukemia

•Mixed phenotype acute leukemia had a predominance of acute lymphoid leukemia–type mutations and cytogenetic abnormalities•Remission induction rates were high with both acute lymphoid leukemia–type and acute myeloid leukemia–type induction regimens•Survival was high after allogeneic transplantation with ablative conditioning•Mixed phenotype acute leukemia with MLL rearrangement has an unfavorable prognosis Mixed phenotype acute leukemia (MPAL) represents a poorly characterized group of acute leukemias that lack an accepted therapeutic approach and are typically associated with poor outcomes. We present our experience of genomic profiling, pretransplantation therapy, and transplantation outcomes for 36 well-characterized pediatric and adult patients with MPAL, defined according to the 2016 World Health Organization leukemia update. A predominance of acute lymphoid leukemia (ALL)–associated mutations and cytogenetic abnormalities was noted. Remission rates after induction appeared comparable among adults (20 of 23) and children (11 of 13) and among those who received ALL (10 of 11) or acute myeloid leukemia–type (21 of 25) induction. Adults underwent transplantation in first remission while children underwent transplantation in the setting of relapse or MLL rearrangement. The median follow-up among the 25 patients who underwent transplantation was 39.6 months and median overall survival was not reached. Relapse after transplantation was associated with MLL rearrangement (P = .022), reduced-intensity conditioning (P