BCL2 and B-cell chronic lymphocytic leukemia: Encouraged by some striking responses in CLL patients to this BH3 mimetic, Abbvie developed an orally available inhibitor with 100-fold greater affinity for BCL-2 than BCL-XL, named ABT-199 (venetoclax).89 Owing to its high subnanomolar affinity for BCL-2 and low binding to BCL-XL, this novel agent does not cause thrombocytopenia.