Enable CAR T cell immunotherapy in glioblastoma by modifying its microenvironment via oncolytic adenovirus encoding...

Recent clinical trials show that CAR T cell therapies can initially blunt tumor growth in patients with glioblastoma (GBM). However, therapeutic efficacy remains limited by the immunosuppressive tumor microenvironment and restricted immune cell trafficking across the blood-brain barrier (BBB). To counteract these challenges, we have utilized the oncolytic adenovirus (OV) Ad5-Δ24-RGD as a platform to overexpress a bispecific T cell engager (BiTE) targeting both CD3 on T cells and the GBM-specific tumor associated antigen IL-13Rα2. We first demonstrated that OV-BiTE can significantly increase the recruitment of T cells to GBM, both in vitro and in vivo. Moreover, OV-BiTE treatment also markedly enhanced CAR T cell infiltration and tumor cytotoxicity in a GBM-BBB spheroid model, possibly through downregulation of endothelial junction protein expression. We then showed that intratumoral injection of OV-BiTE followed by infusion of combined EGFR and EGFRvIII CAR T cells was more effective than OV-BiTE supplemented with either CAR T therapy alone and led to significant tumor reduction in a GBM xenograft mouse model. In conclusion, our multimodal OV-BiTE plus CAR T cell immunotherapy is capable of overcoming the immunosuppressive tumor microenvironment and GBM resistance to treatment.