Evaluation of serum cytokines and acute phase proteins as possible pharmacodynamic biomarkers to monitor endoscopic remission during ustekinumab therapy in patients with Crohn's disease.

Background: Since not all Crohn's disease (CD) patients respond adequately to ustekinumab therapy, biomarkers could aid to monitor treatment response and optimize therapeutic outcomes.

Objectives: To explore the dynamics of serum biomarker concentrations to monitor the response to ustekinumab treatment in CD patients.

Design: Retrospective, exploratory study to evaluate concentrations of serum cytokines and acute phase proteins and their relation to endoscopic remission in CD patients during ustekinumab treatment.

Methods: Serum concentrations of 16 proteins including cytokines and acute phase proteins were measured using the Mesoscale Discovery Platform in serum of healthy controls (n = 13), and CD patients (n = 61) at baseline (week 0), week 8 and week 24 during ustekinumab treatment. Endoscopic remission was defined as simple endoscopic score for CD (SES-CD) <3 after 6 months of therapy.

Results: Absolute concentrations of serum amyloid A protein (SAA; week 8), IL-6 (week 24), AGP (weeks 8 and 24), interferon (IFN)-γ (weeks 8 and 24), lipopolysaccharide binding protein (LBP; weeks 8 and 24) and IL-22 (weeks 8 and 24) were significantly lower in endoscopic remitters compared to non-responders (p-values ranging between <0.001 and <0.05). SAA (week 8) and AGP (week 24) were the biomarkers with the highest area under the ROC curve (AUROC; 0.761 and 0.760, respectively) for identifying patients in endoscopic remission, though their performance was not superior to C-reactive protein (CRP) or faecal calprotectin. AUROCs of the predictive probability of biomarker combinations showed superiority in discriminating endoscopic remitters from non-responders in comparison to single biomarker measurements, but not as compared to faecal calprotectin.

Conclusion: Although not superior to faecal calprotectin, measurement of AGP, SAA, LBF, IFN-γ, IL-6 and IL-22 concentrations, and combinations thereof with or without CRP and faecal calprotectin, during ustekinumab therapy might contribute to adequate monitoring of treatment response in CD patients.