Study C13007 comprised 2 randomized, double-blind, placebo-controlled studies conducted under 1 protocol which, operationally, consisted of 2 phases.~The Induction Phase, designed to establish the efficacy and safety of vedolizumab for the induction of clinical response and clinical remission, and~The Maintenance Phase, designed to establish the efficacy and safety of vedolizumab for the maintenance of clinical response and clinical remission.~The 6-week Induction Phase contained 2 cohorts of participants: Cohort 1 participants were randomized and treated with double-blind study drug, and Cohort 2 participants were treated with open-label vedolizumab. The second cohort was enrolled to ensure that the sample size of Induction Phase responders randomized into the Maintenance Study provided sufficient power for the Maintenance Study primary efficacy analysis. These participants did not contribute to the efficacy analyses performed for the Induction Study. Participants in both cohorts were assessed for treatment response at Week 6.~In the Maintenance Phase vedolizumab-treated participants from both Cohort 1 and Cohort 2 who demonstrated a clinical response were randomized in a 1:1:1 ratio to double-blind treatment with vedolizumab administered every 4 weeks (Q4W), vedolizumab administered every 8 weeks (Q8W), or placebo. Vedolizumab-treated participants who did not demonstrate response at Week 6 continued treatment with open-label vedolizumab, administered Q4W. Participants treated with double-blind placebo in the Induction Phase continued on double-blind placebo during the Maintenance Phase, regardless of treatment response during induction. The Maintenance Phase began at Week 6 and concluded with Week 52 assessments.~After the Week 52 assessments, participants may have been eligible to enroll in Study C13008 (NCT00790933; Long-term Safety Study) to receive open-label vedolizumab treatment. Participants who withdrew early (prior to Week 52) due to sustained nonresponse, disease worsening, or the need for rescue medications may have been eligible to enroll in Study C13008. Participants who did not enroll into Study C13008 were to complete a final on-study safety assessment at Week 66 (or Final Safety visit 16 weeks after the last dose) in the Maintenance Phase of Study C13007.
The primary purpose of this study was to determine the effect of vedolizumab induction treatment on clinical response and remission at 6 weeks and to determine the effect of vedolizumab maintenance treatment on clinical remission at 52 weeks.