Navitoclax (ABT-263) inhibits BCL-2, BCL-XL, and BCL-W simultaneously — covering all the primary anti-apoptotic proteins in senescent cells. In aged mice, navitoclax reduces senescent cell burden by 50–80%, extends healthspan, and improves physical function. Its clinical use for aging is limited by thrombocytopenia: BCL-XL is essential for platelet survival, and navitoclax depletes platelets within hours of dosing.

Will navitoclax ever be usable for aging?

Modified navitoclax variants with reduced BCL-XL (platelet-sparing) activity are in development. If successfully engineered, a navitoclax variant could be the most effective aging senolytic ever created. This remains a research frontier.

Why is navitoclax used in cancer treatment if it's dangerous?

In cancer (CLL, small cell lung cancer), the tumor-killing benefit outweighs the thrombocytopenia risk. Patients are monitored closely with platelet transfusions available. For aging patients without cancer, this risk-benefit calculation is unfavorable.