Elevated plasma interleukin-35 levels predict poor prognosis in patients with non-small cell lung cancer

Interleukin-35 (IL-35) has recently been implicated in tumor immunity. The aim of this study was to explore the clinical role of plasma IL-35 in patients with non-small cell lung cancer (NSCLC). Plasma collected from 106 patients with NSCLC cases and 78 healthy controls (HC) were subjected to IL-35 enzyme-linked immunosorbent assay (ELISA) and relationships between plasma IL-35 levels and clinical characteristics were evaluated. The correlation of IL-35 and overall survival was analyzed using Kaplan-Meier method. The prognostic value of IL-35 was tested using univariate and multivariate analysis. Circulating IL-35 levels were significantly higher in the NSCLC group in comparison with the HC group (21.37 +/- 11.55 pg/ml vs. 10.09 +/- 5.32 pg/ml, p<0.001). Correlation analysis by subgroup indicated that plasma IL-35 correlated positively with tumor TNM stage (p<0.001) and lymph node metastases (p<0.0001). Using a cutoff level of 20.26 pg/ml (median value), IL-35 showed an inverse correlation with overall survival. Univariate and multivariate analysis indicated that plasma IL-35 was an independent prognostic factor for NSCLC patients. Circulating IL-35 in NSCLC patients significantly increased. IL-35 is a promising potential biomarker in prognostication of clinical outcome of NSCLC patients and the regulation of IL-35 expression may provide a new target for the treatment of NSCLC patients.