There are also some studies reported that the EGFR mutation in NSCLC could increase the expression of PD-L1 protein, and TKIs could reduce the amount of PD-L1 protein, the signaling pathways referring to this phenomenon are PI3K-AKT, STAT3, NF-κB, and MEK-ERK signaling pathways (39). Here, STAT3 is linked to non-small cell lung carcinoma.