Immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 or CTLA-4 have shown promising therapeutic effects in the clinical treatment of advanced solid cancers, including melanoma, non-small cell lung cancer (NSCLC), renal cell carcinoma (RCC), urothelial carcinoma (UCC), and classical Hodgkin’s lymphoma. The gene discussed is PDCD1; the disease is melanoma.