PDCD1 and melanoma: Several immunotherapeutic advances, such as anti-programmed cell death 1 (anti-PD-1), anti-programmed death-ligand-1 (anti-PD-L1), and anti-cytotoxic T-lymphocyte-associated antigen 4 (anti-CTLA-4) have become available to better manage moderate to advanced-staged melanoma.191,192 However, the positive response to these compounds is limited to a subsegment of the melanoma population and even then may not be durable over time.