A Study to Learn About the Effectiveness of Etrasimod in People With Ulcerative Colitis

Inclusion Criteria:

• Male and female patients ≥18 and <65 years of age at baseline

• Patients with confirmed diagnosis of ulcerative colitis and who are prescribedetrasimod for moderately to severely active ulcerative colitis as per the productlabel independently of the decision to enroll a patient in this study.

• Evidence of a personally signed and dated informed consent document indicating thatthe patient has been informed of all pertinent aspects of the study.

Exclusion Criteria:

• Presence of clinical findings suggestive of Crohn's disease.

• Severe extensive colitis evidenced by:

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

2. Current evidence of acute severe UC, fulminant colitis, or toxic megacolon 3.Patients with a stoma or planned UC surgical intervention requiringhospitalization.

3. Prior/Concomitant Therapy:

4. any previous exposure to etrasimod including participation in the etrasimodclinical program.

5. any co-medication with one of the following conventional therapies:methotrexate or a thiopurine (azathioprine, mercaptopurine or tioguanine) orwith any of the following advanced therapies for UC: biologics (a TNF, integrinor cytokine antagonist); JAK inhibitors (filgotinib, tofacitinib orupadacitinib) or with any other S1P receptor modulator.

• Not owning a digital device with internet connection and/or not willing to completehealth questionnaires on this device or not capable of using the healthquestionnaire collection tool.

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