Heterologous prime-boost viral vector cancer vaccines have protective effects against a syngeneic mouse model of glioblastoma

Abstract

Abstract Glioblastomas are immunologically “cold” tumors with intense immunosuppressive myeloid cell- and sparse cytotoxic T-cell infiltration. Therefore, viral vector vaccines may be a promising approach to boost the induction of glioblastoma-targeted T cells. It has been previously shown that heterologous prime-boost vaccination with chimpanzee-derived adenovirus ChAdOx1 and modified vaccinia Ankara (MVA) vectors can induce a high magnitude of CD8 +T cells specific for cancer-associated antigens and have therapeutic effects against mouse models of cancer. Therefore, we aimed to evaluate whether using ChAdOx1 and MVA vaccines targeting model antigen P1A, a mouse equivalent to human tumor-associated Melanoma Antigen GenE (MAGE)-type antigens, could have protective effects against a P1A-transfected BGL-1 glioblastoma model. Mice were vaccinated with ChAdOx1/MVA-P1A vaccines, then challenged subcutaneously with P1A-expressing BGL-1 cells. Prophylactic vaccination with ChAdOx1/MVA-P1A significantly prolonged the survival of syngeneic mice subcutaneously challenged with P1A-expressing BGL-1 tumors. Furthermore, different vaccination schedules significantly impacted the magnitude of antigen-specific CD8 +T-cell responses and protective efficacy. Future studies will investigate the protective effects of vaccination against intracranial P1A-expressing BGl-1 tumors. Supported by grants from the Ludwig Institute for Cancer Research, University of Oxford; the NIH Intramural Program (ZIA BC011877), the NIH Oxford-Cambridge Scholars Program, and the Marshall Scholarship Program.