Effect of SLC1A5 overexpression on T cell metabolism and function
Glutamine-dependence of cancer cells reduces local glutamine availability, which hinders anti-tumor T-cell functionality and facilitates immune evasion. We thus speculated that glutamine deprivation might be limiting efficacy of CAR T-cell therapies in cancer patients. We have seen that antigen-specific T cells are unable to proliferate or produce IFN-? in response to antigen stimulation when glutamine concentration is limited. Using multiple myeloma (MM) as a glutamine-dependent disease model, we found that murine CAR-T cells selectively targeting BCMA in MM cells were sensitive to glutamine deprivation. However, CAR-T cells engineered to increase glutamine uptake by expression of the glutamine transporter Asct2 exhibited enhanced proliferation and responsiveness to antigen stimulation, increased production of IFN-?, and heightened cytotoxic activity, even under conditions of low glutamine concentration. Mechanistically, Asct2 overexpression reprogrammed CAR-T cell metabolic fitness, improving basal oxygen consumption rate and glycolytic function that enhanced CAR-T cell persistence in vivo. Accordingly, expression of Asct2 increased the efficacy of BCMA CAR-T cells in syngeneic and genetically-engineered mouse models of MM, which prolonged mouse survival. In patients, reduced expression of Asct2 by MM cells predicted poor outcome to combined immunotherapy and BCMA-CAR T-cell therapy. Our results indicate that reprogramming glutamine metabolism may enhance anti-tumor CAR T-cell functionality in multiple myeloma. This approach may also be effective for other cancers that depend on glutamine as a key energy source and metabolic hallmark. Overall design: murine CD8+ BCMA CART cells were genetically modified to overexpress SLC1A5 or mock. Cells were then left untreated or activated in BCMA coated plates for 16h. After this incubation, total RNA was extracted and analyzed by RNAsec