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

Abstract Recent clinical trials show that CAR-T cell therapies can initially blunt tumor growth in glioblastoma (GBM) patients. However, the tumor microenvironment activates mechanisms that inhibit tumor-killing potential of the CAR-T cells and limit their therapeutic efficacy. To counteract this, we have utilized oncolytic adenovirus (OV) Ad5-Δ24-RGD as a platform to overexpress a bispecific T cell engager (BiTE) targeting both T cell marker CD3 and GBM specific tumor associated antigen IL-13Rα2. We first demonstrated that OV-BiTE could enhance recruitment of T cells to GBM in vitro and in vivo . 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 eradication in a GBM xenograft mouse model. In conclusion, our multimodal OV-BiTE & CAR-T cell immunotherapy is capable of overcoming immunosuppressive tumor microenvironment and GBM resistance to treatment. GRAPHICAL ABSTRACT HIGHLIGHTS Oncolytic adenovirus encoding bispecific T cell engager (OV-BiTE) combines two immunotherapeutic agents into one. OV-BiTE strategy modifies tumor microenvironment and enhances recruitment of T cells to glioblastoma (GBM) in vitro and in vivo . Multimodal OV-BiTE & CAR-T cell immunotherapy effectively reduced tumor mass in a GBM xenograft mouse model and is superior to either immunotherapy alone.