For example, the interaction PD‐1 on a CD8+ T‐cell with its ligand PD‐L1 directly inhibits the effector functions of the CD8+ T‐cells by inducing regulatory pathways that control proliferation, survival, cytokine production, and cytotoxicity.124, 139, 140 Restoration of antitumor responses by blocking these immune checkpoint inhibitors, has been shown to improve outcomes in some cancer patients. This evidence concerns the gene CD8A and cancer.