Remodeling of Tumor Immune Microenvironment by Oncolytic Viruses

Abstract

Oncolytic viruses (OVs) are potential antitumor agents with unique therapeutic mechanisms. They possess the ability of direct oncolysis and the induction of antitumor immunity. OV can be genetically engineered to potentiate antitumor efficacy by remodeling the tumor immune microenvironment. The present mini review mainly describes the effect of OVs on remodeling of the tumor immune microenvironment and explores the mechanism of regulation of the host immune system and the promotion of the immune cells to destroy carcinoma cells by OVs. Furthermore, this article focuses on the utilization of OVs as vectors for the delivery of immunomodulatory cytokines or antibodies.

Keywords: cytokines; immune cells; immune checkpoints; oncolytic virus; tumor immune microenvironment.

Figure 1

Oncolytic virotherapy process the ability to remodel the tumor immune microenvironment (TIME). Oncolytic viruses (OV) infection can enhance the infiltration and activity of immune cells, including innate and adaptive immune cells, within the TIME (A–B). At the same time, these therapeutic viruses reduce the populations of immunosuppressive cells and promote the immunophenotypes of immune cells shift toward antitumor status, thereby, overcoming immune suppression within the TIME (C). In addition, activation of antitumor immunity by oncolytic virotherapy is often accompanied by the production of a variety of proinflammatory cytokines, which is beneficial to further “hot” the TIME (D).