A Study to Investigate the Efficacy and Safety of SAR442970 in Adult Participants With Ulcerative Colitis

Eligibility Criteria

• * Male or female participants aged 18 to 75 years inclusive, at the time of signing the informed consent
• * Participants who have had clinical evidence of active UC for ≥3 months before screening and confirmed by endoscopy during the screening period
• * Must have active moderate-to-severe UC at screening as defined by a modified Mayo Score (mMS) of 5 to 9 (without the Physician Global Assessment (PGA), with a minimum Rectal Bleeding (RB) subscore ≥1, a minimum Stool Frequency (SF) subscore ≥1, mMES ≥2 confirmed by central reader, a minimum sum of all subscores of 5, and a minimum disease extent of 15 cm from the anal verge
• * Must have received prior treatment for UC (either "a" or "b" below or combination of both):
• 1. History of inadequate response to, loss of response to or intolerance to standard treatment with any of the following compounds: amino-salicylates, corticosteroids, methotrexate, azathioprine, or 6-mercaptopurine, or history of corticosteroid dependence (defined as an inability to successfully taper corticosteroids without recurrence of UC) AND history of no prior exposure to Advanced Therapies (ATs), such as a biologic agent used to treat UC or advanced small molecules used to treat UC
• 2. History of inadequate response to, loss of response to or intolerance to treatment with ≥1 approved AT such as a biologic agent used to treat UC or advanced small molecules used to treat UC
• * Contraceptive use by men and women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies
• * Participants are excluded from the study if any of the following criteria apply:
• * Participants with active Crohn's Disease (CD), indeterminate colitis or microscopic colitis
• * Participants with fecal sample positive for culture/ova for aerobic pathogens or positive for Clostridium difficile B toxin in stools
• * Participant with ostomy or ileoanal pouch, prior colectomy or anticipated colectomy during their participation in the study
• * Participants with the following ongoing known complications of UC: fulminant disease, toxic megacolon or colonic dysplasia except for adenoma
• * Participants with intestinal failure or short bowel syndrome requiring Total Parenteral Nutrition
• * History of recurrent or recent serious infection within 4 weeks of screening, or infection(s) requiring hospitalization or treatment with IV anti-infectives within 30 days prior to baseline, or infections(s) requiring oral anti-infectives within 14 days prior to baseline, except as required as part of an anti-Tuberculosis (TB) regimen
• * Known history of or suspected significant current immunosuppression.
• * History or solid organ transplant or splenectomy
• * History of moderate to severe congestive heart failure (New York Health Association Class III or IV), or recent cerebrovascular accident.
• * History of demyelinating disease (including myelitis) or neurologic symptoms suggestive of demyelinating disease
• * Participants with a history of malignancy or lymphoproliferative disease other than adequately treated localized carcinoma in situ of the cervix or nonmetastatic squamous cell carcinoma, or nonmetastatic basal cell carcinoma of the skin
• * Participants with a diagnosis of inflammatory conditions other than UC (including but not limited to systemic lupus erythematosus, systemic sclerosis, myositis, rheumatoid arthritis, primary biliary cirrhosis, multiple sclerosis, Behcet's disease, sarcoidosis, etc.)
• * History of Human Immunodeficiency Virus (HIV) infection or positive HIV serology at Screening
• * History of Interstitial Lung Disease
• * Participants with any of the following results at Screening:
• * Positive (or indeterminate) Hepatitis B surface antigen (HBs Ag) or,
• * Positive total Hepatitis B core antibody (anti-HBc) confirmed by positive Hepatitis B Virus (HBV) Deoxyribonucleic acid (DNA) or,
• * Positive Hepatitis C Virus (HCV) antibody
• * Screening laboratory and other analyses showing abnormal results
• * History of any other condition which, in the opinion of the Investigator, would put the participant at risk by participation in the protocol