Higher Trough Vedolizumab Concentrations During Maintenance Therapy are Associated With Corticosteroid-Free Remission in Inflammatory Bowel Disease

Vedolizumab is an anti-α4β7 biologic approved for ulcerative colitis [UC] and Crohn's disease [CD]. We aimed to examine the association of maintenance vedolizumab concentrations with remission. We performed a cross-sectional multi-centre study of inflammatory bowel disease [IBD] patients on maintenance vedolizumab. A homogeneous mobility shift assay [HMSA] was used to determine trough serum concentrations of vedolizumab and anti-drug antibodies [ATVs]. The primary outcome was corticosteroid-free clinical and biochemical remission defined as a composite of clinical remission, normalized C-reactive protein [CRP] and no corticosteroid use in 4 weeks. Secondary outcomes included corticosteroid-free endoscopic and deep remission. Vedolizumab concentrations were compared between patients in remission and with active disease. Logistic regression, adjusting for confounders, assessed the association between concentrations and remission. In total, 258 IBD patients were included [55% CD and 45% UC]. Patients in clinical and biochemical remission had significantly higher vedolizumab concentrations [12.7 µg/mL vs 10.1 µg/mL, p = 0.002]. Concentrations were also higher among patients in endoscopic and deep remission [14.2 µg/mL vs 8.5 µg/mL, p = 0.003 and 14.8 µg/mL vs 10.1 µg/mL, p = 0.01, respectively]. After controlling for potential confounders, IBD patients with vedolizumab concentrations >11.5 µg/mL were nearly 2.4 times more likely to be in corticosteroid-free clinical and biochemical remission. Only 1.6% of patients had ATVs. In a large real-world cohort of vedolizumab maintenance concentrations, IBD patients with remission defined by objective measures [CRP and endoscopy] had significantly higher trough vedolizumab concentrations and immunogenicity was uncommon.