PDCD1 and melanoma: Immunotherapies, especially those antagonizing immune-checkpoints such as programmed cell death protein 1 (PD1) or cytotoxic T lymphocytes associated protein 4 (CTLA4) (both part of the family of immune-regulatory molecules crucial for general suppression of anti-tumor immunity) have been approved to treat several solid malignancies, such as melanoma, lung cancer, head and neck cancer, renal cell cancer and bladder cancer (among others) [3,4,5].