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

Inclusion Criteria:

Participants are eligible to be included in the study only if all of the following criteria apply:

• Male or female participants aged 18 to 75 years inclusive, at the time of signingthe informed consent

• Participants who have had clinical evidence of active UC for ≥3 months beforescreening and confirmed by endoscopy during the screening period

• Must have active moderate-to-severe UC at screening as defined by a modified MayoScore (mMS) of 5 to 9 (without the Physician Global Assessment (PGA), with a minimumRectal 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 minimumdisease extent of 15 cm from the anal verge

• Must have received prior treatment for UC (either "a" or "b" below or combination ofboth):

1. History of inadequate response to, loss of response to or intolerance tostandard treatment with any of the following compounds: amino-salicylates,corticosteroids, methotrexate, azathioprine, or 6-mercaptopurine, or history ofcorticosteroid dependence (defined as an inability to successfully tapercorticosteroids without recurrence of UC) AND history of no prior exposure toAdvanced Therapies (ATs), such as a biologic agent used to treat UC or advancedsmall molecules used to treat UC

2. History of inadequate response to, loss of response to or intolerance totreatment with ≥1 approved AT such as a biologic agent used to treat UC oradvanced small molecules used to treat UC

• Contraceptive use by men and women should be consistent with local regulationsregarding the methods of contraception for those participating in clinical studies

Exclusion Criteria:

• Participants are excluded from the study if any of the following criteria apply:

• Participants with active Crohn's Disease (CD), indeterminate colitis or microscopiccolitis

• Participants with fecal sample positive for culture/ova for aerobic pathogens orpositive for Clostridium difficile B toxin in stools

• Participant with ostomy or ileoanal pouch, prior colectomy or anticipated colectomyduring their participation in the study

• Participants with the following ongoing known complications of UC: fulminantdisease, toxic megacolon or colonic dysplasia except for adenoma

• Participants with intestinal failure or short bowel syndrome requiring TotalParenteral Nutrition

• History of recurrent or recent serious infection within 4 weeks of screening, orinfection(s) requiring hospitalization or treatment with IV anti-infectives within 30 days prior to baseline, or infections(s) requiring oral anti-infectives within 14days 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 AssociationClass III or IV), or recent cerebrovascular accident.

• History of demyelinating disease (including myelitis) or neurologic symptomssuggestive of demyelinating disease

• Participants with a history of malignancy or lymphoproliferative disease other thanadequately treated localized carcinoma in situ of the cervix or nonmetastaticsquamous cell carcinoma, or nonmetastatic basal cell carcinoma of the skin

• Participants with a diagnosis of inflammatory conditions other than UC (includingbut not limited to systemic lupus erythematosus, systemic sclerosis, myositis,rheumatoid arthritis, primary biliary cirrhosis, multiple sclerosis, Behcet'sdisease, sarcoidosis, etc.)

• History of Human Immunodeficiency Virus (HIV) infection or positive HIV serology atScreening

• 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 positiveHepatitis 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 putthe participant at risk by participation in the protocol

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