Oncolytic Vaccinia Virus and Anti-PD1-based Combination Therapy Restores Antitumor Immunity in Tumor Microenvironment

N. Badrinath, J. Su-Nam, J. Heo, S.Y. Yoo
Pusan National University,

Keywords: combination therapy, oncolytic virotherapy, immune checkpoint blockades


Tumor microenvironments (TME) consist of various types of regulatory cells, and also limit the therapeutic efficacy of most of the drugs. To overcome these hurdles, immunotherapy-based combination therapies are being developed to modify the immunosuppressive nature of TME and block immune checkpoints on immune cells of tumors. In this study, we used cancer-favour oncolytic vaccinia virus (CVV) and α-PD1 to treat mouse colon cancer. Weekly-based intratumoral injection of CVV and intraperitoneal injection of α-PD1 were tested in subcutaneous CT26 tumor models in Balb/c mice. Tumor volume, survival curve and hemotoxylin and eosin staining, and immunohistochemistry-based analysis indicated benefit of co-treatment received groups, especially simultaneous treatment of CVV and α-PD1.The infiltration of CD8+ T-cells also correlated with these results. Furthermore, PD1 and PD-L1 mRNA expression from these groups confirmed the therapeutic efficacy of this combination therapy. CVV and α-PD1-based combination therapy enhanced tumor infiltrating lymphocytes and also tumor cells killing.