2018 May 14;33(5):843–852), PD-L1-expression represents the only clinically available and approved marker to predict response to PD1/PD-L1 axis inhibitors.5–7,14 In first line therapy of advanced NSCLC, pembrolizumab, demonstrated its superiority in comparison to chemotherapy in patients with high PD-L1 expression (>50%).5 Surprisingly, the similar test could not predict response to nivolumab, in a similar setting.14 Indeed, although the expression of PD-L1 may potentially serve as a predictive biomarker to identify patients that respond to treatment, it remains an imperfect biomarker. The gene discussed is CD274; the disease is non-small cell lung carcinoma.