Based on the spectacular response rates observed in clinical trials, specific antibodies targeting cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed cell death 1 (PDCD1, known as PD-1), and more recently, lymphocyte-activation gene 3 (LAG-3) signaling have been approved for the treatment of various tumor types, including melanoma [3,4,5,6,7]. The gene discussed is PDCD1; the disease is neoplasm.