PDCD1 and neoplasm: Supporting our hypothesis, intratumoral delivery of the STING agonist in combination with an anti–PD-1 antibody elicited a dramatic antitumor response, a finding that is in agreement with previous studies suggesting that STING agonists contribute to the trafficking of CD8+ cytotoxic T cells, dendritic cells, and NK cells to the tumor site by upregulating the secretion of cytokines (e.g., CXCL9, CCL2, CCL5, CCL20, IL6)58–61.