Serum interleukin-6 level is associated with response to infliximab in ulcerative colitis

Infliximab is effective in patients with ulcerative colitis (UC); however, one-third of patients do not respond and require additional therapies such as other biologic agents. Therefore, the aim of this study was to analyze the association between pro-inflammatory molecules and clinical efficacy to elucidate possible mechanisms for the non-response to infliximab to aid in treatment selection.

Patients with moderate-to-severe active UC receiving infliximab in our hospital between 2010 and 2016 for whom pre-treatment serum samples were available were retrospectively evaluated. We analyzed the association between serum interleukin (IL)-6, tumor necrosis factor-α (TNF-α) and soluble mucosal vascular addressin cell adhesion molecule-1 (sMAdCAM-1) and the clinical efficacy of infliximab. The primary endpoint was clinical response at the end of the induction period.

Forty-one patients were included in this study. After induction therapy, 27 patients (65.9%) showed a clinical response. Serum IL-6 levels were significantly lower in responders than in non-responders (p = .012), whereas no significant differences were noted in other factors including sMAdCAM-1 and TNF-α. Multivariate analysis identified that serum IL-6 level (odds ratio = 0.72; 95% confidence interval, 0.54-0.96; p = .027) was independently associated with response to infliximab.

Serum IL-6 level is associated with response to infliximab in UC. Elevated concentrations of IL-6 may provide insight to the mechanism of non-response to infliximab.