Immune checkpoint inhibitors (ICIs) can enhance the anti-tumor immune reaction of T cells by targeting cytotoxic T lymphocyte antigen-4 (CTLA-4), and programmed cell death 1 (PD-1) or its ligand (PD-L1), and have been extensively applied for various tumors, including urothelial carcinoma. The gene discussed is PDCD1; the disease is urothelial carcinoma.