Reprograming T cell function through BCL-2 family protein:protein disruption

BCL-2 family of proteins are well-known regulators of cellular apoptosis. Residing at the mitochondria, this family is made up of pro-apoptotic and anti-apoptotic partners whose interactions are regulated by BH3-only proteins. Designed to mimic BH3 proteins and dissociate BCL-2 binding partners to induce cancer cell death, there continues to be discovery of BH3-mimetics that target a range of BCL-2 anti-apoptotic proteins. However, very little is known about how these therapeutics induce BCL-2 family protein:protein interactions (PPIs) changes in other cells, particularly immune cells which heavily rely on the BCL-2 family during ontogeny, homeostasis, activation, and signaling. New evidence demonstrates that targeting of certain anti-apoptotic proteins modulates immune functions via unknown mechanisms distinct from apoptosis. Therefore, there is clinical need and timely opportunity given their increased use to maximize BH3 mimetics through defining the mechanisms of action responsible for these changes and to determine how BCL-2 family targeting affects discrete immune cell populations, causes immune system adaptation, and alters effector functioning. Our long-term goal is to dissect non-apoptotic immunomodulatory effects governed by BCL-2 proteins in T cells and determine how drugging this system with BH3 mimetics affects their function for ultimate translation into T cell-based therapies. Thus, the overall objective of this proposal is to mechanistically characterize the functional consequences of BH3 mimetic therapy on human T cells used for adoptive therapy and discover how BCL-2 PPI alterations control T cell effector function, plasticity, and mitochondrial dynamics. We propose that these studies will significantly broaden the clinical translatability of this drug class and identify novel druggable immune modulatory mechanisms. Based on our preliminary findings, we hypothesize that BCL-2 family anti-apoptotic protein PPI inhibition with venetoclax and other BH3 mimetics will directly alter the effector function of adoptive T cell therapy produced from cells isolated from healthy donors and heavily pretreated patients through adaptive apoptotic, genetic, metabolic, and functional changes. These hypotheses will be tested by pursuing two broad specific aims: 1) Test the potential of BH3 mimetics to alter adoptively transferred T cell function using chimeric antigen receptor (CAR) T cells as a model system and 2) Interrogate PPI alterations within the BCL-2 family interactome at baseline and following BH3-mimetic treatment in CAR T cells to determine the mechanism(s) of action responsible for their immunomodulatory effects. We believe the research proposed in this application is innovative because it seeks to expand the discovery of what we understand about BCL-2 family control of T cell function and determine how BH3 mimetics can be used to modulate T cell activity. We believe this research is of great significance given the growth of BH3 mimetics in treating a wide range of diseases and will provide justification for using this drug class as bona-fide immunomodulatory agents. Project Number: 1R01CA308067-01 | Fiscal Year: 2026 | NIH Institute/Center: National Cancer Institute (NCI) | Principal Investigator: James LaBelle | Institution: UNIVERSITY OF CHICAGO, CHICAGO, IL | Award Amount: $588,289 | Activity Code: R01 | Study Section: Cellular Immunotherapy of Cancer Study Section[CIC] View on NIH RePORTER: https://reporter.nih.gov/project-details/11277126