Venetoclax in patients with previously treated chronic lymphocytic leukemia.
Venetoclax is the first BCL2 inhibitor to enter routine clinical practice. It is an orally bioavailable small molecule that binds BCL2 very specifically. Acting as a pharmacological mimic of the proteins that initiate apoptosis (a so-called BH3-mimetic), venetoclax rapidly induces apoptosis in chronic lymphocytic leukemia (CLL) cells which express high levels of BCL2 and rely on it to maintain their survival. As a single agent, daily venetoclax treatment induced durable responses in 79% of patients with relapsed or refractory CLL or small lymphocytic lymphoma in a Phase 1 study, including complete remissions in 20% of patients. Its use was approved by the FDA in April 2016 for patients with previously treated del(17p) CLL on the basis of a single arm Phase 2 trial demonstrating a 79% response rate and an estimated 1 year progression-free survival of 72% with 400mg/day continuous therapy. This review focuses on venetoclax, its mechanism-of-action, pharmacology and clinical trial data, and seeks to place it in the context of rapid advances in therapy for patients with relapsed CLL, especially those with del(17p) CLL.