BCL2 and cancer: To overcome such apoptosis resistance of cancer cells, great interest in developing specific inhibitors of antiapoptotic BCL-2 proteins, so-called BH3 mimetics, has arisen over the past years, with a first compound [the BCL-2–specific inhibitor venetoclax (Venclexta)] approved by the US Food and Drug and Administration for chronic lymphocytic leukemia and acute myeloid leukemia (Montero and Letai, 2018; Timucin et al., 2019).