Another study showed that the expression of PD-L1 negatively correlates with phagocytic ability against tumor cells, and the blockade of PD-1-PD-L1 increased the phagocytosis ability of macrophage and reduced the progression of tumor, as well as prolonged survival time of mice in mouse models of cancer, indicating that anti-PD-1 therapy may function through a direct effect on macrophages [34]. Here, PDCD1 is linked to cancer.