A Study to Learn About the Safety, Effects and Pharmacokinetics of Study Medication (PF-07054894) for the Treatment of Ulcerative Colitis

Inclusion Criteria:

• Confirmed diagnosis of moderate to severe (Part A) or mild to moderate (Part B) UCfor ≥3 months prior to baseline.

• Active disease beyond the rectum (>15 cm of active disease from the anal verge atthe screening endoscopy).

Part A (moderate to severe): Must have a 5 to 9 score on the modified mayo score, including an endoscopy subscore of at least 2. Part B (mild to moderate): Participants with mMS of 4 to 6, ES of ≥2 and RB score of ≥1

• Must have inadequate response to, loss of response to, or intolerance to at leastone conventional therapy for UC.

• Total body weight >40 kg (88.2 lb).

Exclusion Criteria:

• Presence of indeterminate; microscopic; ischemic; infectious; radiation colitis;diverticular disease; Crohn's disease; colonic stricture; colonic obstruction/resection; presence of cancer.

• History of bowel surgery within 6 months prior to baseline.

• History of significant trauma or major surgery within 4 weeks of screening orconsidered in imminent need of surgery or with elective surgery scheduled to occurduring the study.

• Presence of clinical signs of fulminant colitis or toxic megacolon, primarysclerosing cholangitis and evidence of colonic dysplasia, adenomas or neoplasia.

• Clinically significant infections within 6 months of baseline