FIGURE 1.

Employing OVs as genetic vectors to encode and secret targeted molecules. Upon entering into tumor cells, OVs could be modified to release, and secret several specific molecules including tumor antigens, which could be up-taken by APCs and subsequently presented to tumor-reactive T cells; chemokines like CXCL9 and CXCL10 which could enhance the penetration and activation of CAR-T cells; cytokines like TNF-a, IL-2, IFN-γ, IL-6, and IL-12 which could improve the anti-tumor immune responses and reverse the immunosuppressive status in TME; checkpoint antibodies which could inhibit the T cell immune tolerance mediated by immune checkpoints such as PD-1 and CTLA-4; BiTEs which bind to CD3 and a specific tumor antigen to improve the targeting and activation of antigen-specific T cells. CXCL, CXC-chemokine ligand; IL, interleukin; TNF, tumor necrosis factor; IFN, interferon; APC, antigen presenting cells; TCR, T cell receptor; MHC, major histocompatibility complex.