Because several immune checkpoint inhibitors (ICIs) have been approved as the first- and second-line treatment for advanced urothelial carcinoma (UC), various molecular tests have been proposed as predictive biomarkers, such as tumor mutation burden, programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) assays, and The Cancer Genome Atlas phenotype [1,2]. The gene discussed is CD274; the disease is urothelial carcinoma.