2093 Cellular Engineering of Autologous Glioblastoma-Specific T Cells, Using Nanoparticle-Based Photothermal Therapy

INTRODUCTION: Given the poor prognosis of Glioblastoma (GBM), there is an urgent need for therapies addressing GBM heterogeneity and achieving durable remission. In response, we have developed an autologous T cell product targeting multiple antigens using immunostimulatory photothermal Prussian blue nanoparticle-based photothermal therapy (PBNP-PTT). Our recent studies show that T cells expanded using PBNP-PTT are specific and cytolytic against GBM cell lines in vitro and in vivo. METHODS: To expand autologous GBM-specific T cells, we subjected primary tumor cells, excised during surgery, to PBNP-PTT ex vivo. We then cultured these treated tumor cells with autologous DCs from the patient and stimulated T cells with the primed DCs. RESULTS: In proof-of-concept studies with tumor samples from GBM or metastatic brain tumors, we demonstrated that the PBNP-PTT platform expanded both CD4+ and CD8+ autologous T cells (n=5 patients). These T cells secreted IFN-ɣ specifically and dose-dependently (2.5-fold over controls) and exhibited specific cytolytic activity against target tumor cells (14.8-20.6% killing after 4 h co-culture). TCR sequencing revealed increased Simpson clonality (0.03 to 0.17) and maximum productive frequency (1.7 to 12.0) post-expansion, indicating selective expansion of TCR clones. Immunopeptidomics showed that DCs primed with PBNP-PTT-treated tumor cells present distinct antigens, facilitating personalized tumor-specific antigen presentation. CONCLUSIONS: These findings support using PBNP-PTT to stimulate and expand tumor-specific T cells for autologous ATCT in GBM.