PDCD1 and cancer: PD-1 expression in TAMs correlates negatively with phagocytic potency against tumor cells, and blockade of PD-1 or PD-L1 in vivo increases macrophage phagocytosis, reduces tumor growth and increases the survival of mice in mouse models of cancer in a macrophage-dependent fashion, as depletion of TAMs abrogates these effects (117).