A Study of Intravenous Vedolizumab Administered Every 4 Weeks in Japanese Participants With Moderate to Severe Ulcerative Colitis or Crohn's Disease

The main aim of the study is to learn if 4-weekly vedolizumab improves symptoms of Japanese participants with moderate to severe ulcerative colitis (UC) or Crohn's disease (CD). Vedolizumab is commercially available in Japan for 8-weekly treatment but not for 4-weekly treatment. The study doctors will also monitor side effects from the study treatment. This study will take place in Japan. At the first visit, the study doctor will check if each person can take part. For those who can take part, participants will receive vedolizumab intravenously once every 4 weeks. After 3 infusions of vedolizumab (which will be 12 weeks of treatment), the study doctor will assess if symptoms of the participants have improved. Participants who do not have improved symptoms after 12 weeks of treatment with vedolizumab will stop this treatment. Then, they will visit the study clinic 16 weeks after their last infusion of vedolizumab for a final check-up. Participants who have improved symptoms after 12 weeks of treatment with vedolizumab will continue to receive vedolizumab every 4 weeks. Then, after their last infusion of vedolizumab, the participants will visit the study clinic 16 weeks later for a final check-up. Finally, the study clinic will make a phone call to each participant 6 months after their last infusion to check if they have any health problems.