Venetoclax for the treatment of patients with chronic lymphocytic leukemia

Venetoclax is a potent, selective inhibitor of BCL-2, a key regulator of the intrinsic pathway of apoptosis. In preclinical studies, venetoclax bound to BCL-2 with high affinity and rapidly induced apoptosis in chronic lymphocytic leukemia (CLL) cells. In early-phase clinical trials in CLL, venetoclax treatment led to tumor lysis syndrome in some patients with a large tumor burden, but this risk was subsequently mitigated by a revised study design that included lower initial dosing with intrapatient dose ramp up and close tumor lysis syndrome monitoring and prophylaxis. Other toxicities, such as neutropenia and gastrointestinal adverse events, were manageable. Venetoclax monotherapy resulted in durable and deep responses in patients with relapsed, refractory CLL, including for those with deletion 17p, leading to the approval of venetoclax by the US FDA for relapsed or refractory deletion 17p CLL, and recently to additional approvals in Europe and Canada. Trials also suggest that venetoclax induces deeper and more durable responses when used in combination with rituximab, and combination studies with other agents are ongoing. Phase III trials are also underway, and will provide data on the efficacy and safety of venetoclax in combination with monoclonal antibodies and targeted therapies in larger patient populations.