Lymphocyte inhibitory receptors such as programmed cell death protein 1 (PD‐1) are crucial regulators of this delicate balance, and function to restrain tumor‐infiltrating lymphocytes (TILs) antitumor immunity.7 PD‐1 and its ligands are members of the CD28‐B7 family of receptor–ligand pairs. This evidence concerns the gene PDCD1 and neoplasm.