In a phase‐I trial, nivolumab, an IgG4 antibody directed against PD‐1, produced partial responses in 17% NSCLC patients (n = 122), with durable disease stability.39 This was followed by a phase‐III clinical trial comparing nivolumab and docetaxel (chemotherapy) as a second line treatment for patients with advanced NSCLC, or other cancer.40 The objective response rate was 20% for nivolumab, compared to 9% with docetaxel.40 Following these results, The FDA approved the use of nivolumab in 2016 for advanced NSCLC. Here, PDCD1 is linked to cancer.