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 immunosuppressant
treatment (i.e., azathioprine, 6-mercaptopurine, methotrexate, or tumor necrosis
factor [TNF] inhibitors [maximum of 2 prior TNF inhibitors]) and/or corticosteroid
treatment

- Use of highly effective contraception as defined by the protocol

Exclusion Criteria:

- History of psoriasis or psoriatic arthritis; any other inflammatory skin disorders
requiring oral corticosteroids, immunosuppressants, or biological therapy within the
previous 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, or
planned surgery for UC

- Diagnosis of indeterminate colitis or granulomatous (Crohn's) colitis or toxic
megacolon 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) of
the colon

- History or current evidence of unresectable colonic mucosal dysplasia or history of
high-grade colonic mucosal dysplasia

- Prior treatment with UTTR1147A

- Prior treatment with vedolizumab, etrolizumab, natalizumab, efalizumab, or any other
anti-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 the
protocol