PDCD1LG2 and neoplasm: For example, by binding PD-L1 and PD-L2 on antigen-presenting cells to PD-1 on T cells, they can inhibit excessive activation of T cells, weaken the ability of the immune system to recognize and destroy tumor cells, and make tumor cells escape the surveillance and clearance of the immune system.[34] Since the discovery of PD-1, PD-L1, and cytotoxic T lymphocyte antigen-4 immune checkpoint molecules, ICIs targeting these molecules have shown long-lasting clinical antitumor effects on EC.