ABT-737 binds Bcl-2 and Bcl-XL with high affinity and has shown single-agent efficacy against multiple cell lines as well as in combination with standard therapy in human leukemia and multiple myeloma models [3, 25], lymphoma [26], melanoma [13], cholangiocarcinoma [14] or HNSCC [8]. This evidence concerns the gene BCL2L1 and leukemia.