Even after allogeneic hematopoietic stem-cell transplant (HCT), poor outcomes are typically the case in patients with TP53-mutant (mTP53) acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). The data from recent trials using the combination of eprenetapopt (APR-246) and azacitidine showed positive preclinical results in mTP53 AML/MDS, and this trial sought to assess the efficacy and safety of the eprenetapopt and azacitidine combination as maintenance therapy after allogeneic HCT in patients with mTP53 AML or MDS.