New Progress in the Relationship between Immune Cells, PD-1 
in Tumor Microenvironment and the Efficacy of EGFR-TKIs

In recent years, targeted therapy of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKIs) is the leading treatment modality for patients with advanced non-small cell lung cancer (NSCLC) and EGFR gene mutation. However, with the prolongation of the medication time, most of the patients appeared drug resistance. Tumor microenvironment is the internal environment for the survival and development of tumor cells. The immune response which mediated by immune cells, like regulatory T (Treg), dendritic cells, macrophages, fibroblasts, etc. And the programmed cell death receptor 1 (PD-1) with its ligand PD-1L/PD-2L may participate in the drug resistance of EGFR-TKIs. This review will elaborate the possible mechanism of the interaction of immune cells on EGFR-TKIs in the tumor microenvironment, in order to seek new targets, and further improve the anti-tumor efficacy and prolong the effective time of EGFR-TKIs