A National Multicenter Study of Etrasimod for the Treatment of Patients With Active UC

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that causes symptoms such as bloody diarrhea, abdominal pain, and frequent bowel movements. It can significantly affect patients' quality of life. Etrasimod is an oral medication taken once daily that has been shown in clinical trials to be effective for treating active UC. However, clinical trial results may not fully reflect how the drug works in real-world clinical practice, where patients have more diverse backgrounds and medical conditions. This is a prospective, multicenter, observational registry study conducted at approximately 80 hospitals across China. The study will enroll about 500 Chinese adults with active UC who are receiving or about to start treatment with etrasimod. Participants will be followed for at least 52 weeks. The study does not assign any treatment-all participants receive etrasimod as part of their routine clinical care, and treatment decisions are made by their doctors. The main goal of this study is to describe the characteristics of Chinese adults with active UC who are treated with etrasimod in real-world settings, including their age, sex, disease duration, disease activity, and prior treatments. The study will also track how UC symptoms change over time, how often disease flares occur, and how treatment is adjusted during follow-up. Additional goals include describing medication use patterns, changes in physician-assessed and patient-reported outcomes, treatment-related economic burden, and safety information including adverse events. Data will be collected at baseline and at Weeks 2, 12, 24, and 52 through routine clinic visits, medical records, and patient questionnaires. The study will help provide a more complete understanding of how etrasimod performs in everyday clinical practice in China.

Inclusion Criteria: 1. Age ≥ 18 years at baseline, of any sex. 2. Have a documented diagnosis of active ulcerative colitis (UC) and be judged by the treating physician as likely to benefit from etrasimod therapy. Active UC is defined as an endoscopic subscore ≥ 2, OR a stool frequency subscore (SFS) ≥ 1, OR a rectal bleeding subscore (RBS) ≥ 1. Any disease extent (Montreal classification E1, E2, or E3) is eligible. Participants must provide an endoscopy (including sigmoidoscopy) report obtained within 12 months prior to enrollment. 3. Have been receiving etrasimod for no more than 6 months at the time of enrollment. 4. Voluntarily sign a written informed consent form and have the ability to understand and complete study-related questionnaires and visit procedures. Exclusion Criteria: 1. Have any contraindication to etrasimod use as per the approved prescribing information. 2. Have received prior treatment with ≥ 3 biologic therapies (including infliximab, adalimumab, vedolizumab, guselkumab, risankizumab, and mirikizumab), OR ≥ 2 biologic therapies plus 1 JAK inhibitor (including upadacitinib and tofacitinib). 3. Have any condition that, in the investigator's judgment, may compromise data quality or threaten participant safety. The reason for exclusion must be documented.