27 BRD4, as well as fms-like tyrosine kinase 3 (FLT3), have been suggested as drivers in the pathogenesis of AML,28,29 and preclinical studies of BRD4 inhibitors suggest the potential of these agents as antileukemic drugs.30,31 Although volasertib shows effects on BRD4,27 the cellular effects on BRD4 biomarker modulation are only observed at a concentration of 300 nM, suggesting that the effect on BRD4 may not be a relevant mechanism of action of volasertib. Here, FLT3 is linked to acute myeloid leukemia.