BCL2 and acute myeloid leukemia: Venetoclax, a selective small-molecular inhibitor of B-cell lymphoma-2 (Bcl-2), has been demonstrated that single-agent or combined with other agents are effective and tolerable to AML patients including relapsed or refractory AML patients, especially in elderly patients unfit for intensive chemotherapy, with overall response rate of 19–72% [48–50].