A Study of the Efficacy and Safety of Etrolizumab in Participants With Ulcerative Colitis Who Have Been Previously Exposed to Tumor Necrosis Factor (TNF) Inhibitors

Inclusion Criteria:

• Diagnosis of UC established at least 3 months prior to Day 1
• Moderately to severely active UC as determined by the Mayo Clinic Score (MCS)assessment
• Treatment within 5 years prior to screening with one or two induction regimens thatcontain TNF inhibitors (including TNF inhibitor biosimilars)
• Washout of anti-TNF therapy for at least 8 weeks preceding Day 1
• Background regimen for UC may include oral 5-aminosalicylic acid (5-ASA), oralcorticosteroids, budesonide, probiotics, azathioprine (AZA), 6-mercaptopurine (6-MP),or methotrexate (MTX) if doses have been stable during the screening period
• Use of highly effective contraception as defined by the protocol
• Must have received a colonoscopy within the past year or be willing to undergo acolonoscopy in lieu of a flexible sigmoidoscopy at screening

Exclusion Criteria:

• A history of or current conditions and diseases affecting the digestive tract, such asindeterminate colitis, suspicion of ischemic colitis, radiation colitis, ormicroscopic colitis, Crohn's disease, fistulas or abdominal abscesses, colonic mucosaldysplasia, intestinal obstruction, toxic megacolon, or unremoved adenomatous colonicpolyps
• Prior or planned surgery for UC
• Past or present ileostomy or colostomy
• Any prior treatment with etrolizumab or other anti-integrin agents (includingnatalizumab, vedolizumab, and efalizumab)
• Any prior treatment with anti-adhesion molecules (e.g. anti-MAdCAM-1)
• Any prior treatment with rituximab
• Any treatment with tofacitinib during screening
• Congenital or acquired immune deficiency, chronic hepatitis B or C infection, humanimmunodeficiency virus (HIV) positive, or history of tuberculosis (active or latent)
• Evidence of or treatment for Clostridium difficile or clinically significantcytomegalovirus (CMV) colitis within 60 days prior to Day 1
• Evidence of or treatment for other intestinal pathogens within 30 days prior to Day 1
• History of recurrent opportunistic infections and/or severe disseminated viralinfections
• History of organ transplant
• Any major episode of infection requiring treatment with intravenous (IV) antibioticswithin 8 weeks prior to screening or oral antibiotics within 4 weeks prior toscreening
• Received a live attenuated vaccine within 4 weeks prior to Day 1