PDCD1 and melanoma: Since 2017, anti-PD-1/PD-L1 antibodies have been employed to cure melanoma, cutaneous squamous cell carcinoma, lymphoma, gastric cancer, liver cancer, Merkel cell carcinoma, and other diseases [72,73,74], demonstrating superior overall response rates (ORR) and progression-free survival (PFS) compared to conventional chemotherapy [75,76,77,78].