Immune checkpoint blockade (CPB) with monoclonal antibodies such as ipilimumab targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) or nivolumab/pembrolizumab targeting programmed cell death protein 1 (PD-1) have revolutionized the treatment of advanced melanoma and many other common malignancies. Here, PDCD1 is linked to melanoma.