The U.S. Food and Drug Administration has approved PD-L1 immunohistochemistry (IHC) as a companion diagnostic for NSCLC, gastric, or gastroesophageal junction adenocarcinoma, cervical cancer, urothelial cancer, squamous cell carcinoma of the head and neck and esophagus, and breast cancer. The gene discussed is CD274; the disease is non-small cell lung carcinoma.