It hasprogressed to multiple phase III clinical trials (Figure a,b).BCL-2 is a crucial inhibitor of apoptosis thatis overexpressed in various cancers. Despitepromising phase I–II results as a sensitizer for chemotherapy,G3139 failed to show efficacy in multiple phase III trails. As this drug was well tolerated by patients, the limiting factor is likely target engagementand efficacy. Here, BCL2 is linked to cancer.