PDCD1 and melanoma: Algorithms for current treatment of melanoma patients include vemurafenib, dabrafenib and encorafenib, targeting mutated BRAF (B-RAF proto-oncogene, serine/threonine kinase); trametinib, cobimetinib and binimetinib that inhibit the activity of MEK1/2 (mitogen-activated protein kinase kinase), as well as immune checkpoint inhibitors including nivolumab and pembrolizumab binding to PD-1 (programmed cell death protein 1) and ipilimumab inhibiting CTLA-4 (cytotoxic T-lymphocyte antigen 4) [6–9].