KMT2A and acute myeloid leukemia: Although NPMc+ AML and MLL-fusion AML cells have distinct mutational profiles, these two subtypes share a number of similarities including aberrant HOX gene expression [38, 44–46], activation of the core Brd4 transcriptional program [10, 47, 48], and sensitivity to BET inhibitors in vitro [10, 47, 48].