Therapeutic targeting of BCL-2 during CART cell production augments potency through non-apoptotic adaptive changes

Abstract Targeting the BCL-2 family of proteins, key regulators of cellular apoptosis, with BH3-mimetics has been a major therapeutic goal to overcome cancer cell death resistance. However, beyond their canonical roles in apoptosis, BCL-2 proteins also play vital roles in cellular metabolism, signaling, and, increasingly, immune cell regulation. T cells in particular depend heavily on BCL-2 family proteins during ontogeny and maintenance, yet the broader consequences of pharmacologically inhibiting anti-apoptotic BCL-2 proteins in T cells remain underexplored. Our group has previously demonstrated that BCL-2 inhibition with the BH3-mimetic venetoclax induces gene expression and plasticity changes in murine T cells. Building upon this, we here investigate whether venetoclax-driven T cell reprogramming can be leveraged to enhance adoptive cell therapies, specifically using chimeric antigen receptor (CAR) T cells targeting CD19 as a model system. Our findings reveal that venetoclax treatment during ex vivo expansion of CART cells, prepared from T cells from healthy donors or chemotherapeutically pretreated patients, potently augments antitumor efficacy in a BCL-2-dependent manner. Transcriptomic and functional analyses demonstrate that venetoclax reprograms CART cells by regulating signaling pathways (e.g., IL-2/STAT5 and PI3K/AKT) and metabolic programs (e.g., OXPHOS and glycolysis), yielding CART cells with superior fitness and effector functionalities. These results highlight a novel therapeutic approach using anti-apoptotic drugging to enhance the performance of adoptive T cell therapies and support further examination of venetoclax and other BH3-mimetics as immune modulators.