PDCD1 and melanoma: In addition, a recent clinical trial demonstrated that combinations of nivolumab with ipilimumab showed a better OS than nivolumab monotherapy in melanoma patients with PD-L1 <1%, whereas the OS was comparable between the 2 treatment groups in patients with PD-L1≥1%, suggesting that anti-PD-1 antibody efficacy is largely dependent on PD-L1 expression (16).