In vivo screening reveals cell-intrinsic mediators of solid tumor resistance to CAR T cell-therapy

Chimeric antigen receptor (CAR) T-cell therapy has transformed the treatment of hematologic cancers. However, its efficacy in solid tumors, including pancreatic ductal adenocarcinoma (PDAC), has been limited. By integrating modular CRISPR screening with immunocompetent orthotopic models of PDAC, we identified unknown tumor-intrinsic modulators of CAR T-cell therapy response. Disruption of genes involved in oxidative and proteotoxic stress, particularly the Nrf2 target Slc33a1 , sensitizes PDAC tumors to CAR T-cell killing. Single cell gene expression analyses revealed that CAR-T resistant tumors exhibit reduced Nrf2 pathway activity. Mechanistically, we show that Nrf2 pathway hyperactivation by genetic ablation of Keap1 or expression of a tumor-derived Keap1 allele sensitized PDAC tumors to CAR T-cell therapy. Thus, cell-intrinsic molecular states accompanying malignant progression can sensitize tumor cells to cell-based immunotherapies. These molecular mechanisms could be exploited to augment both the efficacy of CAR-T cell therapy in solid malignancies, and may allow patient stratification by tumor genotype. CAR T-cell therapy remains an unsolved challenge for pancreatic cancer. The discovery of tumor-intrinsic mechanisms of resistance has been largely limited by current experimental models. Using large-scale genomic screening in an orthotopic, immunocompetent model of pancreatic cancer, we uncover a role for cell-intrinsic metabolic states in regulating CAR T-cell response.