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

Inclusion Criteria:

1. Age ≥ 18 years and < 65 years at baseline

2. Patients with confirmed diagnosis of UC who are prescribed etrasimod for moderatelyto severely active UC

3. Evidence of a personally signed and dated ICD indicating that the patient (or alegally acceptable representative)has been informed of all pertinent aspects of thestudy

Exclusion Criteria:

1. The presence of clinical findings suggestive of Crohn's disease

2. Severe extensive colitis evidenced by:

3. Physician judgement that the patient is likely to require hospitalization formedical or surgical intervention of any kind for UC (e.g., colectomy) within 12weeks

4. Current evidence of acute severe UC, fulminant colitis, or toxic megacolon

5. Patients with a stoma or planned UC surgical intervention requiring hospitalization

6. Prior/Concomitant Therapy:

7. Any previous exposure to etrasimod, including participation in the etrasimodclinical program

8. Any co-medication with one of the following conventional therapies:methotrexate or a thiopurine (azathioprine, mercaptopurine, or tioguanine)

9. 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

10. Unwillingness or inability to download the web-based tool to complete ePROs on apersonal device or not capable of using the web-based tool

11. Investigator site staff or Pfizer employees directly involved in the conduct of thestudy, site staff otherwise supervised by the investigator, and their respectivefamily