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.