Abstract
CAR T cell immunotherapy has revolutionized cancer treatment, yet low persistence and progressive T cell exhaustion continue to limit durable clinical responses. In a mouse model of chronic LCMV, we recently demonstrated that microRNA-29a overexpression (miR-29aOE) attenuates exhaustion and promotes long-term persistence of antigen-specific CD8 T cells, while retaining their effector functions. Transcriptomic profiling revealed that miR-29aOE T cells are enriched for gene signatures linked to favorable clinical responses to CAR T therapy and enhanced metabolic programs, including fatty-acid oxidation and oxidative phosphorylation. In contrast, miR-29a-deficient T cells displayed diminished spare respiratory capacity and mitochondrial content, underscoring a central role for miR-29a in maintaining metabolic fitness. These findings led us to hypothesize that miR-29aOE could bolster CAR T-cell persistence and amplify anti-tumor potency. To test this hypothesis, we incorporated miR-29a into second-generation CAR T constructs and evaluated their performance in murine lymphoma models. The results revealed that miR-29a-engineered CAR T cells exhibited superior metabolic capacity pre-infusion, and enhanced post-infusion survival, tumor burden and persistence of tumor infiltrating CAR T cells. These findings establish miR-29a as a promising molecular lever for improving the longevity and efficacy of CAR T cell therapies.