A Prognostic Role Of Programmed Death-ligand1(PD-L1) In Non-small Cell Lung Cancer Patients

[Background and purpose]Recently, there is increasing interest to investigate the target therapy in cancer patients. programmed death-1ligand1(PD-L1) can combine its receptor PD-1, and inhibit the proliferation of T cell, and induce its apoptosis. Up to know, it is largely unknown the expression and role of PD-L1in non-small cell lung cancer. We retrospectively analyzed the relationship of PD-L1expression on primary lung cancer tissue and clinic pathological factors. Additionally, the correlation of PD-L1expression on tumor-associated-macrophage (TAM) and clinic pathological feature was further studied. The potential role of PD-L1for target therapy in NSCLC was discussed.[Materials and methods]208patients with NSCLC, who underwent surgery or CT-guided biopsy in Huadong hospital from2008to2010, were included in this study. Immunohistochemistry staining was performed to evaluate the PD-L1expression level of primary lung cancer tissue. Series sections were also cut, and the adjacent slide was stained for CD68expression. PD-L1expression level was also evaluated on tumor associated macrophages expressing CD68. SPSS13.0version was applied for statistical analysis in this study.[Results]116male patients and92female patients were enrolled into this study, with median age of66years. Collected Data including age, sex, smoking history, histopathological diagnosis, TNM stage, lymph vascular invasion, pleural invasion, and tumor differentiation.136out of206patients were positive for PD-L1on tumor cells, with positive rate of65.3%. A strongly negative correlation between PD-L1expression on tumor cells and lymph node metastasis were seen in NSCLC patients. PD-L1expression was inversely associated with smoking history, the reason of which was unknown. Tumor associated macrophages were successfully identified in206patients using CD68staining.116patients expressed PD-L1on TAM, and its expression was significantly associated with smoking history (P=0.034), well-differentiation (P=0.029) and negative lymph node metastasis (P=0.0096). Spearman analysis showed PD-L1expression on tumor cells was positively associated with that on TAM (r=0.228, p=0.021)[Conclusion]A correlation between PD-L1expression on primary tumor cells and NSCLC lymph node metastasis was found. PD-L1expression on TAM was significantly associated with smoking history and well-differentiation. PD-L1, secreted from TAM, might induce cancer cells apoptosis, and decrease lymph node metastasis.