Dose-finding Study of SAR443122 in Adult Participants With Ulcerative Colitis

This is a randomized, double-blind, placebo controlled, dose-ranging Phase 2 study. The primary objective is to evaluate the efficacy and safety of SAR443122 compared to placebo in participants with moderate to severe UC. Dose selection for further clinical development will be based on the multiple efficacy, safety and PK parameters. The study consists of 4 parallel arms (3 dose groups of SAR443122 vs placebo) to assess the efficacy and safety of SAR443122 in participants with moderate to severe UC. All participants will receive a total of 52 weeks (a 12-week induction treatment phase and a 40-week maintenance phase) of study treatment, except if treatment should be discontinued per investigator's assessment. At the end of the first 12 weeks of induction treatment, all participants in clinical response or remission will be offered study treatment up to 40 weeks and will continue with the same blinded treatment that was assigned. Participants who do not achieve clinical response or remission at the end of the initial 12 weeks induction treatment will roll over in an open-label treatment arm and will be treated with SAR443122 at the highest tested dose. In addition, participants from the maintenance treatment that lose clinical efficacy at any time up to V10/Week 40 (Week 28 of maintenance) will be offered to roll over in the open-label treatment arm with SAR443122 at the highest dose.