Lack of data regarding the PD-L1 status of 21% of patients could be attributed to the fact that they were diagnosed with advanced NSCLC prior to the introduction of first-line pembrolizumab therapy for the PD-L1 > 50% subset of patients, and thus PD-L1 status was not routinely tested for. This evidence concerns the gene CD274 and non-small cell lung carcinoma.