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

Ulcerative colitis (UC) is a chronic inflammatory condition of the large intestine that causes symptoms such as bloody stools, frequent diarrhea, abdominal cramps, and an urgent need to move the bowels. These symptoms often come and go over time, and the unpredictable nature of the disease can severely disrupt daily activities, work, and emotional well-being. While several treatments are available, many patients do not achieve lasting remission or may experience side effects. Etrasimod is a once-daily oral medication that works by modulating immune cell activity in the gut to reduce inflammation. Although clinical trials have shown that etrasimod is effective and generally safe for treating active UC, data from routine clinical practice-where patients have a wider range of health conditions, treatment histories, and lifestyle factors-are still limited, especially in the Chinese population.

To address this gap, this study is designed as a prospective, multicenter, observational registry. It is not a clinical trial, meaning that no study medication is assigned or provided by the research team. All enrolled participants are already prescribed etrasimod by their own doctors as part of their standard medical care. The study will be conducted at approximately 80 hospitals across China and aims to enroll about 500 adults aged 18 years or older who have active UC and have been receiving etrasimod for no more than 6 months at the time of enrollment. Participants will be followed for at least 52 weeks (12 months). Those who have previously used three or more biological therapies, or two biological therapies plus one JAK inhibitor, are not eligible to join.

The study includes two participant groups. The first group consists of patients who are starting etrasimod for the first time at enrollment. The second group includes patients who have already been taking etrasimod for up to 6 months before joining, for whom past medical data will be collected retrospectively. All participants will attend routine clinic visits at baseline (enrollment), Week 2, Week 12, Week 24, and Week 52. These visits align with normal clinical care, and the study does not require any additional tests beyond what doctors would typically order for managing UC.

At each study visit, data will be collected from medical records and patient-completed questionnaires. Information collected includes participants' age, sex, disease duration, disease extent and severity, previous treatments, and any other health conditions. The study will track changes in UC symptoms-such as stool frequency and rectal bleeding-as well as disease flare-ups, adjustments in treatment, and the development of new health issues. Participants will be asked to complete validated questionnaires, including the Inflammatory Bowel Disease Questionnaire (IBDQ), which measures quality of life, and the 8-item Morisky Medication Adherence Scale (MMAS-8), which assesses how well participants follow their prescribed treatment plan. The study will also collect information on healthcare costs, including medication expenses, hospitalization fees, and indirect costs such as transportation and lost work time.

In terms of clinical outcomes, the study will describe disease activity using the partial Mayo score, which evaluates stool frequency and bleeding. For those who undergo routine endoscopy as part of their care, the study will record endoscopic findings and, when available, tissue biopsy results to assess mucosal healing. Blood and stool tests, including C-reactive protein (CRP) and fecal calprotectin (FCP), will also be collected if performed in routine practice. Safety is an important focus; the study will systematically document any adverse events or serious adverse events that occur during follow-up.

A planned interim analysis will be performed when approximately 40% of the target enrollment (about 200 participants) is reached, to assess data quality and recruitment progress. No efficacy comparisons or hypothesis testing will be conducted in this interim review. All final analyses will be descriptive in nature, summarizing participant characteristics, treatment patterns, clinical outcomes, patient-reported outcomes, and safety data over the 52-week period.

The findings from this registry are expected to provide valuable real-world evidence on the use of etrasimod in Chinese adults with active UC. This information will help clinicians better understand how the medication performs in everyday practice, support informed treatment decisions, and ultimately improve the management and quality of life for patients living with UC in China.