c-JUN Enhances CRISPR Knock-In anti-B7-H3 CAR T-cell Function for Treatment of Small Cell Lung Cancer and thoracic SMARCA4-deficient undifferentiated tumors

Small Cell Lung Cancer (SCLC), a highly lethal disease, limits T-cell responses by downregulating Major Histocompatibility (MHC) class I molecules. Because chimeric antigen receptor (CAR) T-cells are not MHC-restricted, they may provide a powerful strategy against SCLC. However, few CAR targets for SCLC have been identified. Here we show that B7-H3/CD276 is expressed on the surface of SCLC and thoracic SMARCA4-deficient undifferentiated tumor (UT) cells that can clinicopathologically mimic SCLC. Thoracic SMARCA4-deficient UT, despite high B7-H3 expression, limit killing by B7-H3 CAR-T cells via secretion of transforming growth factor beta 1 (TGFB1). To overcome tumor-driven CAR-T cell suppression, we knocked-in c-JUN alongside a B7-H3 CAR into the TRAC locus of primary human T-cells utilizing CRISPR/Cas9. Non-viral c-JUN+B7-H3 CAR-T cells show enhanced killing of both SCLC cells with low antigen density and thoracic SMARCA4-deficient UT, providing a platform to address these highly aggressive entities. We also provide evidence that GMP clinical scale manufacturing is feasible for c-JUN+B7-H3 CAR-T cells.