Abstract 4013: Increasing mitochondrial respiration by silencing MCJ/DnaJC15 enhances CD8 CAR-T cell therapy efficacy

Abstract Chimeric antigen receptor (CAR)-T cell therapy is a promising treatment against leukemia and lymphoma. However, poor initial treatment response and post-therapy relapse have found to be common and remained to be resolved. Modulating T cell immunometabolism is considered a novel therapeutic approach to enhance CAR-T cell therapy. We have identified MCJ (DnaJC15) as an endogenous negative regulator of Complex I of the electron transport chain in mitochondria. MCJ is abundantly expressed in mouse CD8 cells relative to other immune cells. We propose that MCJ can be a therapeutic target to enhance mitochondrial respiration in CD8 CAR-T cells. We will show that loss of MCJ in mouse CD8 cells leads to superior anti-tumor response against melanoma. In addition, we will show that MCJ-deficient murine CD8 CAR-T cells have enhanced killing activity against leukemia both in vitro and in vivo. We have recently revealed that MCJ is also expressed in human CD8 cells and the levels of MCJ are heterogenous among human population. Similar to murine CD8 cells, MCJ knockdown in human CD8 cells enhances mitochondrial membrane potential and effector functions. We have designed a new CAR construct to silence MCJ in human CD8 CAR-T cells. MCJ-deficient human CD8 cells show superior cytotoxicity against leukemia with increased mitochondrial metabolism. Together, these data demonstrate that MCJ is a promising target to improve CAR-T cell therapy through modulating the T cell metabolism. We are currently investigating the effect of MCJ-deficient CD8 CAR-T cells against solid malignancy. Citation Format: Meng-Han Wu, Emily L. Giddings, Felipe Valenca-Pereira, Catherine Pham-Danis, Francesca Cendali, Michael C. Yarnell, Amanda J. Novak, Jorge Henao-Mejia, Richard A. Flavell, Angelo D'Alessandro, Mark Eric Kohler, Mercedes Rincon. Increasing mitochondrial respiration by silencing MCJ/DnaJC15 enhances CD8 CAR-T cell therapy efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4013.