Abstract
Dendritic cell (DC) vaccines have been shown to stimulate tumor antigen-specific CD8+ T cells; however, this strategy has demonstrated variable clinical efficacy likely due to immune escape mechanisms that can induce tumor-specific CD8+ T cell dysfunction. Herein, we evaluated the functional characteristics of DC vaccine-induced CD8+ T cells with regard to immune checkpoint inhibitors in gastric cancer patients who were administered Wilms tumor protein-1 (WT1)-targeted DC vaccine. We observed the upregulation of the inhibitory molecule, TIGIT and the inhibitory T cell co-receptors PD1 and Tim3 in limiting WT1-specific CD8+ T cell growth and function in GC patients. TIGIT-expressing PD1+Tim3- CD8+ T cells were the largest subset, while TIGIT+PD1+Tim3+ was the most dysfunctional subset of WT1-specific CD8+ T cells in gastric cancer patients. Importantly, the co-inhibition of TIGIT, PD1, and Tim3 pathways enhanced the growth, proliferation, and cytokine production of WT1-specific CD8+ T cells. In conclusion, our data suggests that targeting TIGIT, PD1, and Tim3 pathways may be important in reversing immune escape in patients with advanced gastric cancer.