Progress in the Study on PD-L1 Inhibitor in the Treatment of EGFR-Mutant Non-Small Cell Lung Cancer

Immunotherapy has opened up a new area for human health and cancer treatment by enhancing the human immune system and removing in vivo tumor cells to suppress "tumor immune escape". Recent studies had demonstrated that the efficacy of immune checkpoint inhibitors in patients with epidermal growth factor receptor (EGFR) mutation non-small cell lung cancer (NSCLC) was unsatisfactory. The possible mechanisms mainly include low expression of programmed cell death protein ligand 1 (PD-L1), suppressive immune microenvironment and low tumor mutant burden. The series analysis of changes to immune microenvironment of patients with EGFR-mutant NSCLC, immune checkpoint inhibitors and researches progress of their combined application with TKI is expected to bring new hope to the treatment of patients with EGFR-mutant NSCLC. This paper major signaling pathways involved in the regulation of PD-L1 expression and the preclinical and clinical studies on the treatment with immune checkpoint inhibitors or combined with EGFR-TKIs in patients with EGFR-mutant NSCLC.