Ulcerative Colitis (UC) is a disease that causes swelling and sores in the colon (part of the digestive system). This study is checking how well a new medicine called SAR442970 works for adults with moderate to severe UC. It's a phase 2b study, meaning it's testing for safety and how well it works. The study is randomized (participants are randomly assigned to groups), and double-blind (neither participants nor doctors know who is getting the medicine or a placebo). It will last up to 168 weeks (a little over 3 years), with treatment for up to 158 weeks, including an optional long-term part for some.

• Length: Study lasts up to 168 weeks.
• Visits: Regular visits needed throughout the study.
• Eligibility: Must have moderate to severe UC, be 18-75 years old, and meet other health criteria.

Participants must have tried other UC treatments before and follow certain rules, like using contraception. Some health conditions might exclude you from joining. Check with the study team to see if you can join.