Ulcerative colitis (UC) is a disease where the inner lining of the large intestine gets swollen and sores form. This study is focused on testing two drugs: Vedolizumab and Tofacitinib. Vedolizumab stops white blood cells from entering the gut, while Tofacitinib reduces immune system activity. The study aims to see how these drugs work together in adults with moderate to severe UC.

Participants will first receive both drugs for 8 weeks. If they respond well, they will continue with just Vedolizumab for 44 more weeks. The total study lasts up to 76 weeks. After the last dose, participants will be monitored for 26 weeks to ensure safety. The study will take place in the United States and Canada.

• The study lasts up to 76 weeks with 26 weeks follow-up after the last treatment.
• All participants start with both drugs for 8 weeks; responders continue with one drug for 44 more weeks.
• Participants must have moderate to severe UC and may have tried up to 2 previous treatments.