Venetoclax (trade name Venclexta, also known as ABT-199) is a selective and orally bioavailable small-molecule inhibitor of BCL-2, an antiapoptotic protein. BCL-2 and its related proteins BCL-XL and MCL-1 bind to and sequester pro-apoptotic signals in the cell, causing a down-regulation of apoptosis. As an oncogene and an important regulator of apoptosis, BCL-2 overexpression therefore results in increased tumor cell survival and resistance to chemotherapy. FDA approved Venetoclax in April 2016 for the treatment of patients with chronic lymphocytic leukemia (CLL) with 17p deletion, as detected by an FDA approved test, who have received at least one prior therapy. Also this drug in phase 3 clinical trial in combination therapy for the treatment patients with refractory myeloma and Acute Myeloid Leukemia. Common side effects include neutropenia, nausea, anemia, diarrhea, upper respiratory tract infection. Major side effects include tumor lysis syndrome and severe neutropenia.