An Early-Stage Study in Multiple Clinics of How Afimkibart May Affect the Body's Processing of Medicines That Rely on Cytochrome P450 Enzymes in Participants With Ulcerative Colitis

• Body weight >= 40kg
• Agreement to adhere to the contraceptive requirements

UC Specific Inclusion Criteria:

• Confirmed diagnosis of UC with supportive clinical, endoscopic, and histopathological evidence
• Active UC confirmed by endoscopy (flexible sigmoidoscopy or colonoscopy) extending >=15 cm from the anal verge
• Moderately to severely active UC, defined as an modified Mayo score of 5 to 9 points, including a Mayo endoscopic subscore of 2 or 3, confirmed through centrally read endoscopy

Inflammatory Bowel Disease (IBD) Exclusion Criteria:

• Current diagnosis of Crohn's disease (CD),abdominal/intrabdominal/perianal fistula and/or abscess, indeterminant colitis, IBD-unclassified, microscopic colitis, ischemic colitis, infectious colitis, radiation colitis, or active diverticular disease
• Presence of an ostomy or ileoanal pouch
• Current diagnosis or suspicion of primary sclerosing cholangitis

Medical History Exclusion Criteria:

• Lack of peripheral venous access
• Any major surgery within 6 weeks prior to screening or a major surgery planned during the study
• History of alcohol, drug, or chemical abuse < 1 year prior to screening