The expression of ligand of programmed death-1 (PD-L1) and PD-L2 was considered as one of the most important biomarkers for PD-1 inhibitor assignment; a high expression of PD-L1 could be a predictive factor of response to anti-PD-1 therapy, and in some malignancies, such as non-small-cell-lung cancers, the evaluation of PD-L1 expression was inseparably linked to the indication of immunotherapy [52]. The gene discussed is CD274; the disease is non-small cell lung carcinoma.