We next sought to determine whether pharmacological inhibition of DOT1L methyltransferase activity, using the recently developed small molecular inhibitor EPZ5676 (EPZ; also called pinometostat) [19, 27], which was tested in phase I clinical trials for adult and pediatric MLL-translocated leukemia (NCT01684150 and NCT02141828, respectively) [28], also impairs the DNA damage response and repair. The gene discussed is KMT2A; the disease is leukemia.