Immunotherapy, which allows immune cells to attack cancer cells, results in long-term survival in patients with several different tumors, such as melanoma, non-small cell lung cancer, and renal cell carcinoma.22 Cancer immunotherapy has undergone major breakthroughs during the past decades, impressive results being reported by several studies.23, 24 One key target of cancer immunotherapies has been the PD-1–PD-L1 pathway.25, 26 Programmed death ligand 1 (PD-L1), also known as cluster of differentiation 274 (CD274), is expressed on many cancer cells. The gene discussed is CD274; the disease is melanoma.