A Study Comparing the Efficacy and Safety of Etrolizumab to Infliximab in Participants With Moderate to Severe Ulcerative Colitis Who Are Naïve to Tumor Necrosis Factor (TNF) Inhibitors

Inclusion Criteria:

• Moderately to severely active UC as determined by the Mayo Clinic Score assessment (MCS)
• Naive to treatment with any anti-TNF inhibitor therapy (including TNF inhibitorbiosimilars)
• An inadequate response to or intolerance of prior corticosteroid and/orimmunosuppressant treatment
• Background regimen for UC may include oral 5-aminosalicylate (5-ASA), oralcorticosteroids, budenoside multi-matrix system (MMX), probiotics, azathioprine (AZA), 6-mercaptopurine (6-MP), or methotrexate (MTX) if doses have been stable during thescreening period
• Use of highly effective contraception during and at least 24 weeks after the last doseof study drug

Exclusion Criteria:

• A history of or current conditions and diseases affecting the digestive tract, such asindeterminate colitis, suspicion of ischemic, radiation or microscopic colitis,Crohn's disease, fistulas or abdominal abscesses, colonic mucosal dysplasia,intestinal obstruction, toxic megacolon, or unremoved adenomatous colonic polyps
• Prior or planned surgery for UC
• Past or present ileostomy or colostomy
• Have received non-permitted inflammatory bowel disease (IBD) therapies (includingnatalizumab, vedolizumab, efalizumab, and tofactinib)
• History of moderate or severe allergic or anaphylactic/anaphylactoid reactions tochimeric, human, or humanized antibodies; fusion proteins, or murine proteins;hypersensitivity to etrolizumab or any of its excipients
• Chronic hepatitis B or C infection, Human deficiency virus (HIV) or tuberculosis (active or latent)