PDCD1 and non-small cell lung carcinoma: To further confirm that the NSCLC cells with T790M EGFR mutation would have increased level of PD-L1 promoter methylation when subjected to anti-PD1 treatment, the NSCLC cell line SK-MES-1 with wild type of EGFR was used for establishing cell lines with EGFR mutations (L858R and T790M) via target genome editing technology.