Pooled screening for CAR function in glioblastoma

Chimeric antigen receptor therapies have demonstrated potent efficacy in treating B cell malignancies, but have yet to meaningfully translate to solid tumors. Here, we utilize our pooled screening platform, CARPOOL, with the hopes of expediting the discovery of CARs with anti-tumor functions necessary for solid tumor efficacy. We performed selections in primary human T cells expressing a library of 1.3x10^6 3rd generation CARs targeting IL13Ra2, a cancer testis antigen commonly expressed in glioblastoma. Selections were performed for cytotoxicity, proliferation, and persistence upon repeated antigen challenge under immunosuppressive conditions. One enriched CAR triggered potent cytotoxicity and long-term proliferation upon in vitro tumor rechallenge. It also showed significantly enhanced persistence and antigen-specific tumor control in a xenograft model of human glioblastoma. Taken together, this work demonstrates the utility of extending CARPOOL to diseases beyond B-ALL and represents the largest exploration of signaling combinations in human primary cells to date.