P454 Early vedolizumab trough levels predict mucosal healing in inflammatory bowel disease

Abstract

BackgroundThere is evidence for an exposure-efficacy relationship for vedolizumab therapy in patients with inflammatory bowel disease (IBD). In contrast to anti-tumour necrosis factor (anti-TNF) agents, the correlation between vedolizumab trough levels during induction therapy and mucosal healing remains unknown.MethodsThis was a prospective, observational study of all vedolizumab-treated patients in 3 referral IBD centres between June 1, 2014 and March 31, 2017. Vedolizumab trough levels during induction therapy were correlated with mucosal healing within the first year after treatment initiation.ResultsA total number of 82 vedolizumab-treated patients, 43 with ulcerative colitis and 39 with Crohn’s disease, underwent assessment of mucosal healing by magnetic resonance imaging and/or endoscopy in the first year after treatment initiation. The median disease duration at the start of vedolizumab treatment was 10 years (IQR 6–16.2 years) and 67 of 82 (79.4%) patients were previously exposed to anti-TNF therapy. Median vedolizumab trough levels in the overall population were 27 μg/ml (IQR 21.2–33.8 μg/ml) at Week 2, 23 μg/ml (IQR 15–34.5 μg/ml) at Week 6 and 10.7 μg/ml (IQR 4.6–20.4 μg/ml) at Week 14 after the first infusion. Only median vedolizumab trough levels at Week 6 during induction differed between patients with mucosal healing and without mucosal healing within the first year after treatment initiation (26.8 μg/ml vs. 15.1 μg/ml, p-value = .035). A cut-off trough level of 18 μg/ml at Week 6 predicted mucosal healing within the first year after the start of vedolizumab with a sensitivity, specificity, accuracy, positive predictive value and negative predictive value of 88.2%, 66.7%, 79%, 78.9%, and 80.0%, leading to an area under the receiver operating curve of 0.735 (95% CI 0.531–0.939).ConclusionsVedolizumab trough levels above 18 μg/ml at Week 6 predicted mucosal healing within the first year after treatment initiation. Early therapeutic drug monitoring might improve timely detection of vedoluzimab-treated IBD patients in need for an intensified dosing regimen.