PD-L1 expression is associated with advanced non-small cell lung cancer

Lung cancer is the most common cause of cancer-associated mortalities worldwide. Novel immunotherapies have been developed to improve the clinical outcomes of non-small cell lung cancer (NSCLC). Antibodies against programmed cell death protein 1 (PD-1) and programmed cell death protein 1 ligand 1 (PD-L1) have been tested in clinical trials, and anti-PD-1 antibody has been approved for the treatment of NSCLC. The aim of the present study was to assess expression of PD-1, PD-L1 and programmed cell death protein 1 ligand 2 (PD-L2) in 48 patients with NSCLC, using immunohistochemical staining. The results found that 35.4% (17/48) of patients were positive for PD-1 expression, 64.6% (31/48) were positive for PD-L1 expression and 45.8% (22/48) were positive for PD-L2 expression. Neither PD-1 nor PD-L2 expression was associated with gender, histology, differentiation status, tumor stage or lymph node metastasis. PD-L1 expression was not associated with gender, histology, differentiation status or lymph node metastasis; however, PD-L1 expression was significantly increased in stage III NSCLC (85.7% PD-L1+) compared with stage I/II NSCLC (55.9% PD-L1+) (P=0.049).