PDCD1LG2 and melanoma: Improving cancer-related immune resistance is mainly achieved through immune checkpoint blockade therapy, and multiple immune checkpoint-targeting agents have been identified and clinically applied to treat lung cancer, esophageal cancer, melanoma, etc. Therapeutic targets include but are not limited to PD-L1 (CD274), PD-L2 (PDCD1LG2), CD80, CD86, and CD70, and novel applied therapies have shown promise in lung cancer and melanoma treatment6–10.