Therapeutic blockade of the inhibitory proteins cytotoxic T-lymphocyte associated-protein 4 (CTLA-4) and programmed cell death protein-1 (PD-1) on exhausted CD8+ T cells using immune checkpoint inhibitors (ICI) is associated with tumor remission, particularly in subsets of patients with prominent CD8+ T cell infiltration of tumors3,4. The gene discussed is PDCD1; the disease is neoplasm.