Abstract A10: In vivo CRISPR screen reveals how to drive therapeutic T cell function to solid tumors


 Chimeric antigen receptor (CAR)-T cell therapy is emerging as a promising option for cancer immunotherapy. Although CAR-T cell therapy has excellent efficacy in the treatment of hematologic malignancies, it has largely failed in patients with solid tumors due to several problems, such as homing and trafficking. Here, we performed an in vivo targeted CRISPR-Cas9 screens to identify a molecular regulator of off-target trafficking of CAR-T cells, and identified ST3 b-galactoside a-2,3-sialyltransferase1 (St3gal1) as a major negative factor of CAR-T cells migration. Analysis of Maackia amurensis lectin-II immunoprecipitates revealed that CD18 in activated CD8+ T cells is the glycoproteins bearing the St3gal1-specific α2,3-sialylated glycans. Overexpression of St3gal1 in activated T cells induced glycosylation of lymphocyte function-associated antigen-1 (LFA-1), which inhibited endocytic recycling of LFA-1, leading to the nonspecific accumulation of T cells in the lungs. We checked that the expression of St3gal1 increased, and that of bII-spectrin, a key LFA-1 associated cytoskeleton molecule, decreased as T cells were activated. Engineered CAR-T cells with enhanced bII-spectrin expression showed decreased St3gal1 expression and induced a significant reduction in tumor growth in mice through improved tumor-specific homing. In addition, the expression level of bII-spectrinin anti-CD19 CAR-T cells injected in patients with large B-cell lymphomas correlated positively with patient response to treatment but negatively with systemic toxicity. Our findings suggest that St3gal1-bII-spectrin axis controls tissue-specific migration of therapeutic T cells delivered intravenously, which can improve tumor-specific homing of CAR-T cells in cancer immunotherapy.
 Citation Format: Yeonsun Hong, Minsoo Kim. In vivo CRISPR screen reveals how to drive therapeutic T cell function to solid tumors [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy; 2022 Oct 21-24; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(12 Suppl):Abstract nr A10.