Therapeutic Efficacy of IL7/CCL19-Expressing CAR-T Cells in Intractable Solid Tumor Models of Glioblastoma and Pancreatic Cancer.

Cancer immunotherapy using immune checkpoint inhibitors and its combination with other anticancer therapies has emerged as a new standard of care because of the encouraging therapeutic effects in various solid cancers. Nonetheless, glioblastoma and pancreatic cancer remain resistant to immunotherapy and represent intractable cancers with the poorest prognosis. We investigated the therapeutic effects of next-generation chimeric antigen receptor (CAR) T cells producing IL7 and chemokine (C-C motif) ligand 19 (CCL19; referred to as 7 × 19 CAR-T) in these intractable cancers. Cytotoxic activities and therapeutic effects of 7 × 19 CAR-T were evaluated in vitro and in vivo, in a model using EGFR variant III (EGFRvIII)-positive glioblastoma and anti-EGFRvIII CAR-T generated from healthy donor peripheral blood mononuclear cells (PBMC), or a model using HER2-positive pancreatic cancer organoids and anti-HER2 CAR-T generated from the same patient's PBMC. Anti-EGFRvIII 7 × 19 CAR-T exhibited cytotoxic activity specific to EGFRvIII-positive tumor, induced complete rejection of glioblastoma with massive T-cell infiltration and tumor cell death in the tumor tissues, and consequently prolonged mouse survival. Anti-HER2 7 × 19 CAR-T demonstrated a potent cytotoxic activity against autologous HER2-positive pancreatic cancer organoids and induced complete rejection of autologous tumor along with prolonged mouse survival. Our results suggest that 7 × 19 CAR-T could become a therapeutic option for glioblastoma and pancreatic cancer. To the best of our knowledge, this is the first study to demonstrate the therapeutic efficacy of next-generation CAR-T in an autologous model using patient-derived tumor organoids and CAR-T generated from the same patient's PBMC, in which unwanted allogeneic immune responses are fully excluded. SIGNIFICANCE: Despite the clinical development of CAR T-cell therapy, its efficacy in solid cancers has yet to be established. This study explored the therapeutic potential and immunologic mechanisms of IL7/CCL19-producing CAR-T therapy in preclinical solid cancer models of glioblastoma and pancreatic cancer. We found that IL7/CCL19-producing CAR-T cells generated from the patient's PBMC showed potent therapeutic effects against the solid cancer model established by inoculating organoids from the autologous tumor tissue.