The PD-1/PD-L1 checkpoint has been extensively studied, and PD-1 and PD-L1 inhibitors have induced encouraging clinical responses in patients with NSCLC, melanoma, Hodgkin lymphoma, urothelial carcinoma, RCC, and many other cancers [4, 5, 41–45]. The gene discussed is PDCD1; the disease is urothelial carcinoma.