...we assessed the effect of EPZ4777, a small-molecule DOT1L inhibitor in NPM1mut leukemias. DOT1L-inhibition (DOT1L-i) led to a profound reduction in cell proliferation and colony-forming potential in the human and both murine NPM1mut leukemia models...DOT1L-i resulted in significant repression of HOX genes in human and murine leukemia cells...