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

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

• Participants are inadequate or non-responders, have shown loss of response, or are intolerant 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 screening and during screening period.

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

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

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

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