EGFR and non-small cell lung carcinoma: The result of their subgroup analysis based on PD-L1 expression levels (≥1%, ≥5% and ≥10%) showed that the Nivolumab monotherapy group was superior to the docetaxel second-line chemotherapy group in patients with positive PD-L1 expression (9).The level of PD-L1 expression remains unclear in NSCLC patients resistant to EGFR-TKIs therapy.