An Observational Study of Etrasimod in Adult Patients With Moderate to Severe Ulcerative Colitis

Who May Qualify: 1. Age ≥ 18 years and \< 65 years at baseline 2. Patients with confirmed diagnosis of UC who are prescribed etrasimod for moderately to severely active UC 3. Evidence of a personally signed and dated ICD indicating that the patient (or a legally acceptable representative)has been informed of all pertinent aspects of the study Who Should NOT Join This Trial: 1. The presence of clinical findings suggestive of Crohn's disease 2. Severe extensive colitis evidenced by: 1. Physician judgement that the patient is likely to require hospitalization for medical or surgical intervention of any kind for UC (e.g., colectomy) within 12 weeks 2. Current evidence of acute severe UC, fulminant colitis, or toxic megacolon 3. Patients with a stoma or planned UC surgical intervention requiring hospitalization 4. Prior/Concomitant Therapy: 1. Any previous exposure to etrasimod, including participation in the etrasimod clinical program 2. Any co-medication with one of the following conventional therapies: methotrexate or a thiopurine (azathioprine, mercaptopurine, or tioguanine) 3. Any co-medication with one of the following advanced therapies for UC: biologics (a TNF, integrin or cytokine antagonist; JAKi \[filgotinib, tofacitinib, or upadacitinib\]) or with any other S1P receptor modulator 5. Unwillingness or inability to download the web-based tool to complete ePROs on a personal device or not capable of using the web-based tool 6. Investigator site staff or Pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family Always talk to your doctor about whether this trial is right for you.