The delivery of durable remission induced by anti-programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) immune checkpoint inhibitors in a subset of cancer types and patients has motivated many basic and translational investigators to focus their attention and resources towards studying the role of the immune cell-tumor interplay in cancer growth, progression, and recurrence [9–11]. The gene discussed is PDCD1; the disease is cancer.