IL‐27 improves adoptive CD8+ T cells’ antitumor activity via enhancing cell survival and memory T cell differentiation

IL‐27 is an anti‐inflammatory cytokine that triggers enhanced antitumor immunity, particularly cytotoxic T lymphocyte responses. In the present study, we sought to develop IL‐27 into a therapeutic adjutant for adoptive T cell therapy using our well‐established models. We have found that IL‐27 directly improved the survival status and cytotoxicity of adoptive OT‐1 CD8⁺ T cells in vitro and in vivo. Meanwhile, IL‐27 treatment programs memory T cell differentiation in CD8⁺ T cells, characterized by upregulation of genes associated with T cell memory differentiation (T‐bet, Eomes, Blimp1, and Ly6C). Additionally, we engineered the adoptive OT‐1 CD8⁺ T cells to deliver IL‐27. In mice, the established tumors treated with OT‐1 CD8⁺ T‐IL‐27 were completely rejected, which demonstrated that IL‐27 delivered via tumor antigen–specific T cells enhances adoptive T cells’ cancer immunity. To our knowledge, this is the first application of CD8⁺ T cells as a vehicle to deliver IL‐27 to treat tumors. Thus, this study demonstrates IL‐27 is a feasible approach for enhancing CD8⁺ T cells’ antitumor immunity and can be used as a therapeutic adjutant for T cell adoptive transfer to treat cancer.