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

Inclusion Criteria:

• Participants who have clinical evidence of active Ulcerative Colitis [UC] for ≥3months before screening as confirmed by endoscopy during the screening period.

• Participants must have a minimum disease extent of 15 centimeters from the analverge.

• Participants are inadequate or non-responders, have shown loss of response, or areintolerant to at least 1 of following approved treatments: amino-salicylate,corticosteroids, immunosuppressants or biologics other than natalizumab (Tysabri®)or small molecules.

• Participants on corticosteroids must be on a stable dose ≥2 weeks prior to screeningand during screening period.

• Participants on methotrexate, azathioprine or 6- mercaptopurine must be on treatmentfor at least 8 weeks prior to screening; and on a stable dose ≥4 weeks prior toscreening and during screening period.

• Participants on oral 5-aminosalicylates, mesalamine or sulfasalazine must be on astable dose for ≥4 weeks prior to screening and during screening period.

• Participants on advanced therapies must have 1) last administration at least 5half-lives prior to randomization, or 2) undetectable level of the biologic in theirblood prior to randomization.

• Contraceptive use by men and women should be consistent with local regulationsregarding the methods of contraception for those participating in clinical studies.Women participants should not be pregnant or breastfeeding.

Exclusion Criteria:

• Participants with Crohn's Disease (CD).

• Participants with diagnosis of indeterminate colitis or microscopic colitis.

• Participants with stool sample positive for culture for aerobic pathogens or Cdifficile.

• Participants with prior colectomy or anticipated colectomy during theirparticipation in the study.

• Participants with presence of ileal pouch or ostomy.

• Participants with fulminant disease or toxic megacolon.

• Participants with colonic dysplasia except for adenoma.

• Participants with intestinal failure or short bowel syndrome requiring TotalParenteral Nutrition (TPN).

• Participants with history of recurrent or recent serious infection that has notresolved within 4 weeks prior to randomization.

• Participants presenting with active malignancies or recurrence of malignancy withinthe 5 years before screening.

• Participants with a history or presence of another significant illness thataccording to the investigator's judgment would adversely affect the subject'sability to participate in this study.

• Participants presenting with fever (≥38°C) or persistent chronic or active recurringinfection within 4 weeks prior to the Screening Visit requiring treatment withantibiotics, antivirals, or any history of frequent recurrent infections deemedunacceptable per investigator's judgment.

• Participants who were administered any live (attenuated) vaccine within 3 monthsprior to the randomization Visit.

• Participants with a history of recurrent herpes zoster.

• Participants with uncontrolled diabetes, defined as HbA1c ≥9.0% at the ScreeningVisit.

• Participants with active tuberculosis (TB) or non-tuberculous mycobacterialinfection, or a history of incompletely treated active or latent TB per localguidelines will be excluded from the study unless it is documented by a specialistthat the participant has been adequately treated and can now start treatment withthe RIPK1 kinase inhibitor.

• Participants presenting with opportunistic infections within six months prior toscreening or while receiving anti-TNF treatment in the last 6 months.

• Participants undergoing hemodialysis or peritoneal dialysis.

• Participants with a known history of Human Immunodeficiency Virus (HIV) infection orpositive HIV serology at screening.

• Participants with Positive Hepatitis B surface antigen (HBsAg) or positive HepatitisB core antibody (HBcAb); and/or positive Hepatitis C antibody (HCV) at the ScreeningVisit. Participants that were treated for HCV and clear the virus documented by HCVRNA by PCR below the limit of quantification can be eligible.

• Positive COVID-19 test, suspected COVID-19 infection or known exposure to COVID-19during the screening period.

• History of COVID-19 infection within 4 weeks prior to Screening; history ofmechanical ventilation or extracorporeal membrane oxygenation (ECMO) due to COVID-19infection within 3 months prior to Screening or with residual significantcomplications from COVID-19 making it unsafe for the participant to enter thisstudy.

• Participants presenting alcohol or drug dependency within the 2 years prior to theScreening Visit.

• Participants with unexplained, uncontrolled, or untreated thyroid disease orunexplained abnormal serum prolactin levels at screening.

• Participants under cyclosporine, mycophenolate mofetil, sirolimus (rapamycin),thalidomide or tacrolimus treatment within 4 weeks prior to screening.

• Participants with previous exposure to natalizumab (Tysabri®).

• Participants with previous exposure to RIPK1 inhibitor.

• Participants under antidiarrheals within 2 weeks prior to screening and duringscreening period.

• Participants under prednisone >25 mg/day (or equivalent).

• Participants under budesonide >9 mg/day.

• Participants who received intravenous corticosteroids or cytapheresis therapy within 2 weeks prior to screening or during screening.

• Participants who were rectally administered topical 5-aminosalicylate orcorticosteroids within 4 weeks prior to screening.

• Participants who received therapeutic enema or suppository, other than required forcolonoscopy or flexible sigmoidoscopy within 4 weeks prior to screening or duringscreening.

• Participants who received antibiotics for UC or gastrointestinal infection within 4weeks prior to screening.

• Participants who have taken other investigational medications within 2 months or 5half--lives, (whichever is longer) prior to screening.

• Presence of significant laboratory findings at the Screening Visit.

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.