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.