Infliximab Concentration Thresholds During Induction Therapy Are Associated With Short-term Mucosal Healing in Patients With Ulcerative Colitis

BACKGROUND & AIMS: Mucosal healing is an independent predictor of sustained clinical remission in patients with ulcerative colitis (UC) treated with infliximab. We investigated whether infliximab concentrations during induction therapy are associated with short-term mucosal healing (STMH) in patients with UC. METHODS: We performed a retrospective, single-center analysis of data collected from a tertiary referral center from 101 patients with UC who received scheduled induction therapy with infliximab at weeks 0, 2, and 6 and had an endoscopic evaluation at baseline and after induction therapy. STMH was defined as Mayo endoscopic sub-score <= 1, assessed at weeks 10-14, with baseline sub-score >= 2. Infliximab concentrations were evaluated in serum samples collected at weeks 0, 2, 6, and 14 of infliximab therapy by using an enzyme-linked immunosorbent assay we developed. RESULTS: Fifty-four patients (53.4%) achieved STMH. Patients with STMH had a higher median infliximab concentration at weeks 2, 6, and 14 than patients without STMH. A receiver operating characteristic (ROC) analysis identified infliximab concentration thresholds of 28.3 (area under the ROC curve [AUROC], 0.638), 15 (AUROC, 0.688), and 2.1 mu g/mL (AUROC, 0.781) that associated with STMH at weeks 2, 6, and 14, respectively. Multiple logistic regression analysis identified infliximab concentration >= 15 at week 6 (P = .025; odds ratio, 4.6; 95% confidence interval, 1.2-17.1) and >= 2.1 mu g/mL at week 14 (P = .004; odds ratio, 5.6; 95% confidence interval, 1.7-18) as independent factors associated with STMH. CONCLUSIONS: In an analysis of data from real-life clinical practice, we associated infliximab concentrations during the induction therapy with STMH in patients with UC.