In a 2016 phase III trial of pembrolizumab monotherapy in metastatic NSCLC with PD-L1 expression ≥ 50%, improvement in progression-free survival (PFS) was observed in the overall population, with no PFS improvement reported among never-smokers, whereas PFS improvement was observed among smokers [120]. This evidence concerns the gene CD274 and non-small cell lung carcinoma.