This randomized, open-label, international, phase 3 study evaluated the efficacy and safety of nivolumab, a fully human IgG4 programmed death 1 (PD-1) immune-checkpoint-inhibitor antibody, compared with docetaxel in patients with advanced squamous-cell non–small-cell lung cancer (NSCLC) who had disease progression during or after first-line chemotherapy. The primary endpoint was overall survival. Patients were randomly assigned to receive nivolumab at a dose of 3 mg per kilogram of body weight every 2 weeks or docetaxel at a dose of 75 mg per square meter of body-surface area every 3 weeks. The median overall survival was 9.2 months with nivolumab and 6.0 months with docetaxel, representing a 41% lower risk of death (hazard ratio, 0.59; 95% CI, 0.44 to 0.79; P<0.001). The response rate was 20% with nivolumab and 9% with docetaxel (P=0.008). The median progression-free survival was 3.5 months with nivolumab and 2.8 months with docetaxel (hazard ratio for death or disease progression, 0.62; 95% CI, 0.47 to 0.81; P<0.001). Treatment-related adverse events of grade 3 or 4 were reported in 7% of patients in the nivolumab group compared with 55% in the docetaxel group. The study concluded that nivolumab provided significantly better overall survival, response rate, and progression-free survival compared with docetaxel, regardless of PD-L1 expression level.This randomized, open-label, international, phase 3 study evaluated the efficacy and safety of nivolumab, a fully human IgG4 programmed death 1 (PD-1) immune-checkpoint-inhibitor antibody, compared with docetaxel in patients with advanced squamous-cell non–small-cell lung cancer (NSCLC) who had disease progression during or after first-line chemotherapy. The primary endpoint was overall survival. Patients were randomly assigned to receive nivolumab at a dose of 3 mg per kilogram of body weight every 2 weeks or docetaxel at a dose of 75 mg per square meter of body-surface area every 3 weeks. The median overall survival was 9.2 months with nivolumab and 6.0 months with docetaxel, representing a 41% lower risk of death (hazard ratio, 0.59; 95% CI, 0.44 to 0.79; P<0.001). The response rate was 20% with nivolumab and 9% with docetaxel (P=0.008). The median progression-free survival was 3.5 months with nivolumab and 2.8 months with docetaxel (hazard ratio for death or disease progression, 0.62; 95% CI, 0.47 to 0.81; P<0.001). Treatment-related adverse events of grade 3 or 4 were reported in 7% of patients in the nivolumab group compared with 55% in the docetaxel group. The study concluded that nivolumab provided significantly better overall survival, response rate, and progression-free survival compared with docetaxel, regardless of PD-L1 expression level.