Exploratory biomarker analyses were performed in 190 patients (nivolumab, 98 out of 229 (43%); placebo, 92 out of 232 (40%)) with evaluable paired tumour samples from screening and blood samples from ≥1 time point during the study for whole-exome sequencing (WES). These individuals constituted the biomarker-evaluable population. The most common reasons for exclusion were samples