A Study to Evaluate the Efficacy, Safety, and Pharmacokinetics of UTTR1147A Compared With Placebo and With Vedolizumab in Participants With Moderate to Severe Ulcerative Colitis (UC)

Inclusion Criteria:

• Diagnosis of UC
• Confirmation of moderately to severely active UC, defined by the Mayo Clinic Score
• Inadequate response, loss of response, or intolerance to prior immunosuppressanttreatment (i.e., azathioprine, 6-mercaptopurine, methotrexate, or tumor necrosisfactor [TNF] inhibitors [maximum of 2 prior TNF inhibitors]) and/or corticosteroidtreatment
• Use of highly effective contraception as defined by the protocol

Exclusion Criteria:

• History of psoriasis or psoriatic arthritis; any other inflammatory skin disordersrequiring oral corticosteroids, immunosuppressants, or biological therapy within theprevious year; or primary sclerosing cholangitis
• History of cancer as defined by the protocol
• Significant uncontrolled comorbidity, such as cardiac, pulmonary, renal, hepatic,endocrine, or gastrointestinal disorders (excluding UC)
• Prior extensive colonic resection, subtotal or total colectomy, or proctocolectomy, orplanned surgery for UC
• Diagnosis of indeterminate colitis or granulomatous (Crohn's) colitis or toxicmegacolon within 12 months prior to screening
• Suspicion of ischemic colitis, radiation colitis, or microscopic colitis
• Current fistula or history of fistula, pericolonic abscess and stricture (stenosis) ofthe colon
• History or current evidence of unresectable colonic mucosal dysplasia or history ofhigh-grade colonic mucosal dysplasia
• Prior treatment with UTTR1147A
• Prior treatment with vedolizumab, etrolizumab, natalizumab, efalizumab, or any otheranti-integrin agents
• Prior treatment with rituximab
• Use of prohibited therapies, as defined by the protocol, prior to randomization
• Congenital or acquired immune deficiency
• Evidence or treatment of infections or history of infections, as defined by theprotocol