BCL2 and B-cell chronic lymphocytic leukemia: Recently, Navitoclax was re‐engineered to create a potent, orally bioavailable inhibitor selective for Bcl‐2, ABT‐199 (Venetoclax) [Souers et al., 2013], which has become the first clinically approved small molecule targeting a protein–protein interaction for treating CLL (chronic lymphocytic leukemia) [Green, 2016].