Targeting DOT1L with inhibitors like pinometostat (EPZ-5676) has shown promise in MLL-rearranged leukemia xenograft models, achieving significant tumor regression [122], while in the clinical setting, although well tolerated, pinometostat has shown modest clinical activity in adult leukemia (NCT01684150) [123]. The gene discussed is KMT2A; the disease is leukemia.