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P142. Sharp decrease in calprotectin as a biomarker for remission in UC patients under infliximab therapy

M. De Vos1, O. Dewit2, J. Vandevoort3, F. Baert4, G. D'Haens5, F. Fontaine6, S. Vermeire7, A. Colard6, D. Franchimont8, T. Moreels9, D. Staessen10, L. Terriere11, B. Vander Cruyssen1, E. Louis12

1University Hospital, Gent, Belgium; 2UCL St Luc, Brussels, Belgium; 3OLV Hospitaal, Aalst, Belgium; 4Heilig Hart Hospital, Roeselaere, Belgium; 5Imelda Hospital, Bonheiden, Belgium; 6Clinique St Joseph, Liège, Belgium; 7University Hospital, Leuven, Belgium; 8ULB Erasme, Brussels, Belgium; 9University Hospital, Antwerpen, Belgium; 10AZ Monica, Antwerpen, Belgium; 11ZNA Middelheim, Antwerpen, Belgium; 12CHU Sart Tilman, Liège, Belgium

Background: Faecal calprotectin correlates with endoscopic and histological disease activity in patients with ulcerative colitis (UC).

Aims: To evaluate the evolution of calprotectin levels under infliximab induction therapy.

Patients and Methods: 53 patients with active UC from 17 centers were treated with infliximab therapy (5 mg/kg) at baseline, week 2, and week 6. Patients were evaluated at each infusion and week 10 by clinical Mayo score and lab testing. Faecal calprotectin was measured every week. Sigmoidoscopies were performed at baseline, week 6 and week 10. Endoscopic remission was further defined by a score of 1 or less.

Results: After 10 weeks, 2 patients stopped therapy due to inefficacy. Three patients stopped due to safety reasons. Additionally, 12 patients had missing data, mostly attributable to refusal of the week 10 sigmoidoscopy. Those patients were excluded from complete case analysis, further depicted with an asterisk (*).

Infliximab therapy induced endoscopic remission in 63%* of patients. When all 53 patients were analyzed with multiple imputation, this overall estimated remission rate decreased to 59%.

Median calprotectin levels decreased from 1767 (IQR 3140)* at baseline to 72.5 (IQR 444)* at week 10 (p < 0.001). Moreover, patients who went in endoscopic remission at week 10 showed a significant steep decrease of calpro scores between baseline and week2 (p < 0.001) compared to patients who did not show a remission (Figure). A calprotectin level of maximal 50 mg/kg or a decrease of at least 80% at week 2 predicted an endoscopic remission at week 10 with a specificity of 67% and sensitivity of 54%.

Clinical Mayo score and faecal calprotectin measurements showed an excellent correlation with endoscopic remission, reflected by an AUC of ROC analyses of 0.94 (0.87–1) for Mayo score and 0.91 (0.81–1) for calpro measurements at week 10*: all patients (63%*) with a Calpro score of <50, and all patients (63%*) with a normal clinical Mayo score (= 0) were in colonoscopic remission.

Similar results were obtained with ITT repeated measures analysis: AUC of 0.97 (0.94–1) for the Clinical Mayo score and 0.85 (0.77–0.92) for the calpro measurements.

Conclusions: Infliximab therapy induces an endoscopic remission in about 60% of UC patients with active disease.associated with a fast and significant decrease of faecal calprotectin levels. Faecal caprotectin levels are as reliable as clinical Mayo score to evaluate the effect of infliximab therapy and correlate with endoscopic scores.