However, BCL-XL-driven thrombocytopenia has been dose limiting in patients with hematological malignancies or small cell lung cancer.14, 15, 16, 17, 18, 19 Consequently, we developed the BCL-2-selective inhibitor venetoclax (ABT-199) that shows superior affinity to BCL-2 relative to navitoclax and circumvents BCL-XL-driven thrombocytopenia.20 This attribute may permit attainment of higher plasma concentrations that translate into improved response rates in patients with BCL-2-dependent malignancies. The gene discussed is BCL2L1; the disease is Thrombocytopenia.