The purpose of this study is to evaluate the efficacy of RO7837195 compared with placebo in participants with moderately to severely active ulcerative colitis for whom prior treatment with conventional and/or advanced therapies has failed.

This study consists of up to 5-week screening period, a 12-week induction phase, a 40-week active treatment extension, and a safety follow-up period following the last dose of study treatment. The induction phase will be placebo-controlled and after its completion, all participants will receive treatment with active study drug, regardless of the treatment response.

Inclusion Criteria:

• Diagnosis of ulcerative colitis (UC) established at least 3 months
• Moderately to severely active UC assessed by mMS
• Inadequate response, loss of response, or intolerance to conventional or advanced therapies for UC

Exclusion Criteria:

• Prior extensive colonic resection, subtotal or total colectomy, or planned surgery for UC
• Diagnosis of Crohn's disease or indeterminate colitis
• Treatment with an advanced therapy targeted at tumor necrosis factor-like cytokine 1A (TL1a)
• Inadequate response, loss of response, or intolerance to treatment of UC with an advanced therapy targeted at IL-12 and/or IL-23

For eligible studies, qualified researchers may request access to individual patient level clinical data. See Roche's commitment to transparency of clinical study information here: https://go.roche.com/data\_sharing