Etrasimod is an oral, once-daily, selective sphingosine 1-phosphate_1,4,5 receptor modulator for the treatment of moderately to severely active ulcerative colitis (UC). While etrasimod demonstrated efficacy in randomised controlled trials, understanding its effectiveness in an observational setting is crucial.

EFFECT-UC is a prospective, multinational, non-interventional study to evaluate the real-world effectiveness of etrasimod in adults with moderately to severely active UC. The study consists of a 52-week treatment period and a 28-day safety follow-up period and aims to enrol ~300 patients per cohort. Eligible patients (18–64 years) are advanced therapy naïve or experienced and are initiating etrasimod in a real-world clinical setting. Treatment will be guided independently by the clinician’s judgement. Patient-reported outcomes will be collected electronically throughout the study and daily for the first 2 weeks. Exploratory data, including faecal calprotectin, endoscopy and intestinal ultrasound, will be collected at predefined visits or during standard care. Primary endpoints are symptomatic remission at week 12 and week 52. Secondary endpoints include patient-reported outcome 2 (combined rectal bleeding and stool frequency subscores) response at week 12 and week 52 and corticosteroid-free symptomatic remission at week 52.

Ethics approval was obtained for all sites. Recruitment is underway for cohort 1, comprising patients from the UK, Germany and Canada. Interim results for this cohort are expected in 2026 and final results in 2028; these will be submitted for publication in peer-reviewed journals and presented at appropriate congresses.

NCT06294925.