Advanced-stage non-neuroendocrine carcinomas should be tested for programmed cell death ligand 1 (PD-L1) expression status as patients with a PD-L1 Tumor Proportion Score (TPS) ≥ 50% are eligible for first-line treatment with the anti-PD-L1 therapy, pembrolizumab. The gene discussed is CD274; the disease is neuroendocrine carcinoma.