TAMs have been shown to facilitate the immune escape of tumor cells through various mechanisms, including downregulation of antigen presentation by other TAMs and DCs, suppression of effector cytotoxic T cells through the recruitment of regulatory T cells (Tregs), secretion of cytokines, and binding of ligands to programmed cell death 1 (PD‐1) or cytotoxic T lymphocyte antigen‐4 (CTLA‐4) on T cells [89]. Here, PDCD1 is linked to neoplasm.