PDCD1 and melanoma: Anti-CTLA-4 (Ipilimumab) and anti-PD-1 (Pembrolizumab, Nivolumab) antibodies are commonly used agents in the immunotherapeutic practice, as immune checkpoint inhibitors (ICIs); their impact on the immune system significantly changed the prognosis of melanoma by increasing patients’ responsiveness, thus increasing the efficacy of therapy [8,9].