A Study to Evaluate IBI112 in the Treatment of Moderate to Severe Active Ulcerative Colitis

Inclusion Criteria:

1. Diagnosis of ulcerative colitis at least 3 months ago, including endoscopy evidencesupporting UC and histopathological evidence supporting UC diagnosis;

2. Patients with moderate to severe ulcerative colitis, defined as modified Mayo Score ≥4 and endoscopic score ≥2;

3. Subject must have received at least one prior treatment or first use of a biologicalagent:

Exclusion Criteria:

1. Diagnosis of ischemic colitis, infectious colitis, radiation colitis, microscopiccolitis, uncertain colitis, etc., or crohn's disease;

2. UC lesions were limited to rectum or involved colon < 15cm;

3. Evidence of toxic hirschsprung's disease was found during screening;

4. History or evidence of atypical hyperplasia of the colon, adenomatous polyps (notremoved before entering the study) or gastrointestinal tumors;