Although as a predictive biomarker PD-L1 expression in NSCLC has limitations, PD-L1 expression in NSCLC is the only FDA-approved biomarker linked to specific PD-1/PD-L1 pathway blockade and is expected to predict a response to anti-PD-1/PD-L1 antibodies (4). This evidence concerns the gene PDCD1 and non-small cell lung carcinoma.