Overexpression of interleukin-35 associates with hepatocellular carcinoma aggressiveness and recurrence after curative resection

Background: Aberrant expression of interleukin-35 (IL-35) has been implicated in dampening antitumour immunity. The aim of this study was to explore the prognostic significance of IL-35 expression in patients with hepatocellular carcinoma (HCC) following curative resection. Furthermore, we aimed to formulate an effective prognostic nomogram for HCC after hepatectomy. Methods: Immunohistochemistry was applied to explore IL-35 expression as well as CD39(+)Foxp3(+) and Foxp3(+) regulatory T cell (Treg) infiltration in tissue microarrays in primary cohort comprising 210 randomly selected HCC patients who underwent curative resection. The results were further verified in an independent validation cohort of 138 HCC patients. Results: Patients with higher expression of IL-35 are more likely to suffer postoperative recurrence. Interleukin-35 was also identified as an independent prognostic factor for recurrence free survival in multivariate analysis. No correlation was detected between IL-35 expression and Foxp3(+) Treg infiltration, whereas significant positive correlation was found between IL-35 expression and CD39(+)Foxp3(+) Treg infiltration. In addition, CD39(+)Foxp3(+) Treg infiltration was also an independent predictor for postoperative recurrence. The nomogram comprising tumour size, tumour vascular invasion, IL-35 and CD39(+)Foxp3(+) Tregs had better predictive accuracy when compared with BCLC stage for RFS. These results were further validated in the validation cohort. Conclusions: Our data suggest for the first time that IL-35 expression correlates with HCC aggressiveness and emerged as a novel independent prognostic factor for recurrence, thus conferring the rationale to develop a novel therapy of targeting IL-35. Furthermore, IL-35 should be incorporated into nomogram to generate a more accurate predictive model.