10033-IM-2 IDENTIFICATION OF THERAPEUTIC TARGET ANTIGENS USING PATIENT DERIVED GLIOBLASTOMA AND THEIR APPLICATION TO CAR-T THERAPY

Abstract

Introduction: New therapies for glioblastoma (GBM) are urgently needed due to its poor prognosis and chimeric antigen receptor T (CAR-T) cell therapy is one of the promising strategies. CAR-T cell therapy targeting EGFRvIII,HER2, and IL13Rα2 have been tested for GBM, but have limited efficacies. To further develop CAR-T cell therapy, cell surface targets that is highly specific for GBM cells are needed. In this study, we applied this strategy to search for GBM-specific cell surface targets using patient derived tumor spheres. Methods: Patient derived tumor spheres was established from GBM surgical specimens, and immunized to Balb/c mice. The B cells from the mice were fused with myeloma cells, immortalized, and cultured nonclonally to obtain a number of monoclonal antibodies reacted GBM cells. The obtained antibodies were reacted with GBM cells and normal brain cells, and those that specifically react to GBM were selected by flowcytometry to obtain antibody candidates that could be specifically expressed on the surface of GBM cells. Then, we generated CAR-T cells derived from the obtained antibody and confirmed anti-tumor effect of CAR-T cells in vitro by ELISA. Results: Approximately 25,000 antibody-producing strains were generated. Within these candidates, we identified antibody X, which reacted with several GBM samples and does not reacted with several normal brain cells. The antibody X is a reported to be a cell adhesion molecule. The CAR-T cells derived from the antibodies X produced IL-2 and IFNγ significantly in co-culture with GBM cells. Conclusion: In this study, we identified antigen X and analyzed its anti-tumor effect in vitro. The antigen X has been reported to be associated with the progression of solid tumors and is expected to be a tumor-specific antigen. Further studies are necessary to examine whether the CAR-T cells targeting antigen X have anti-tumor effect in vivo.