PDCD1 and melanoma: Frontline therapy for patients with melanoma includes the combination of Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) and Programmed Cell Death Protein-1 (PD-1) blockade, which show objective response rates of 57.6% in patients with cutaneous melanoma1, a progression-free survival of 11.5 months, and an overall survival rate of 52% at the 5-year follow-up2,3.