Enitociclib potentiates the cytotoxicity of venetoclax in KMT2A-r leukemia cells. (A) Four KMT2A-r leukemia cell lines were treated with enitociclib, venetoclax, or a combination of both (constant ratios) for 24 hours. (B) Endogenous levels of BCL-2 and MCL-1 are shown in 4 KMT2A-r cell lines. (C) Venetoclax-sensitive (MV4-11) and venetoclax-resistant (INL2) KMT2A-r cell lines were treated with enitociclib (50 nM for MV4-11 and 100 nM for INL2), venetoclax (15 nM for MV4-11 and 5 μM for INL2), or a combination of the 2 drugs for 6 and 24 hours. Levels of cleaved PARP were measured by western blotting. (D) Venetoclax-resistant (INL2) KMT2A-r cell line was treated with enitociclib (100 nM), venetoclax (5 μM), or a combination of the 2 drugs for 6 hours; and protein levels of MCL-1 and BCL-2 were measured by western blotting.