Etrasimod as Prevention of Pouchitis

Inclusion Criteria: * Male or female aged ≥ 18 years (verified at screening) * Ability to provide written informed consent and to be compliant with protocol assessments (verified at screening) * Diagnosed with UC and underwent TPC with IPAA for medically refractory disease or dysplasia (verified at screening) * Screening may take place at any time from one month to two years after the final surgical stage * High-risk of developing acute pouchitis - defined as fulfilling at least one of the criteria defined in section 2 (verified at screening) * Patients with 1 prior episode of acute pouchitis can be enrolled - after a minimum period of 4 weeks after completion of a course of antibiotics and resolution of symptoms of pouchitis * Symptomatic remission defined by a symptom mPDAI subscore ≤2 points at the baseline visit (verified at screening, baseline) * Adequate hematological function defined by white blood cell count ≥ 3.5 × 109/L with absolute neutrophil count (ANC) ≥ 1.5 × 109/L, absolute lymphocyte count (ALC) ≥ 0.8 × 109/L, platelet count ≥ 100 × 109/L, and hemoglobin ≥ 8 g/dL (verified at screening) * Healthcare professional-confirmed history of varicella or a full course of vaccination against varicella zoster virus (VZV) or a positive antibody test to VZV (verified at screening) * 12-lead electrocardiogram (ECG) that showed no clinically significant abnormalities as defined by the clinician's judgement (verified at screening) * Females must be non-pregnant, as determin…