PDCD1 and melanoma: In the clinic, melanoma patients who were treated with immune checkpoints inhibitors targeting PD-1 (Programmed cell Death protein 1), PD-L1 (Programmed cell Death protein ligand 1) and CTLA-4 (Cytotoxic T-Lymphocyte-associated antigen 4) can become resistant and harbored an upregulated EZH2.