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Atypical teratoid/rhabdoid tumors (ATRTs) typically arise in the central nervous system (CNS) of children under 3 years of age. Despite intensive multimodal therapy (surgery, chemotherapy and, if age permits, radiotherapy), median survival is 17 months.sup.1,2. We show that ATRTs robustly express B7-H3/CD276 that does not result from the inactivating mutations in SMARCB1 (refs. .sup.3,4), which drive oncogenesis in ATRT, but requires residual SWItch/Sucrose Non-Fermentable (SWI/SNF) activity mediated by BRG1/SMARCA4. Consistent with the embryonic origin of ATRT.sup.5,6, B7-H3 is highly expressed on the prenatal, but not postnatal, brain. B7-H3.BB.z-chimeric antigen receptor (CAR) T cells administered intracerebroventricularly or intratumorally mediate potent antitumor effects against cerebral ATRT xenografts in mice, with faster kinetics, greater potency and reduced systemic levels of inflammatory cytokines compared to CAR T cells administered intravenously. CAR T cells administered ICV also traffic from the CNS into the periphery; following clearance of ATRT xenografts, B7-H3.BB.z-CAR T cells administered intracerebroventricularly or intravenously mediate antigen-specific protection from tumor rechallenge, both in the brain and periphery. These results identify B7-H3 as a compelling therapeutic target for this largely incurable pediatric tumor and demonstrate important advantages of locoregional compared to systemic delivery of CAR T cells for the treatment of CNS malignancies. CAR T cells administered intracerebroventricularly or intratumorally exhibit more rapid kinetics, reduced systemic toxicity and greater therapeutic potency as compared to intravenously delivered CAR T cells in atypical teratoid/rhabdoid tumor xenograft mouse models., Author(s): Johanna Theruvath [sup.1] , Elena Sotillo [sup.1] , Christopher W. Mount [sup.2] , Claus Moritz Graef [sup.1] , Alberto Delaidelli [sup.3] , Sabine Heitzeneder [sup.1] , Louai Labanieh [sup.1] [...]