A Protocol of Icotrokinra Therapy in Adult and Adolescent Participants With Moderately to Severely Active Ulcerative Colitis

The purpose of this protocol is to evaluate the efficacy (how well it works), safety and tolerability of oral icotrokinra as therapy in adult and adolescent participants with moderately to severely active ulcerative colitis (UC, a chronic disease of the large intestine in which the lining of the colon becomes inflamed and develops tiny open ulcers).

Inclusion Criteria: * Diagnosis of ulcerative colitis (UC) established at least 12 weeks before screening including both endoscopic evidence and a histopathology report consistent with a diagnosis of UC * Moderately to severely active UC, defined as a baseline (Week I-0) modified Mayo score of 5 to 9, inclusive, using the endoscopy subscore obtained during the central review of the screening video endoscopy * An endoscopy subscore greater than or equal to (\>=) 2 as obtained during central review of the screening video endoscopy * Adolescent Participants: body weight must be \>= 40 kilograms (kg) at baseline (Week I-0) * Adult female participants of childbearing potential and all adolescent female participants must have a negative highly sensitive serum pregnancy test (beta-human chorionic gonadotropin \[β-hCG\]) at screening and a negative urine pregnancy test at Week I-0 prior to administration of study intervention and agree to further pregnancy tests * Demonstrated an inadequate response to, or failure to tolerate conventional therapy but are naïve to advanced therapies (ADT naïve), or inadequate response to (that is, primary or secondary nonresponse) or failure to tolerate advanced therapy defined as biologics and/or advanced oral agents for the treatment of UC (ADT-inadequate responder \[IR\]) as defined in the protocol Exclusion Criteria: * Participants with current known complications of UC such as fulminant colitis, toxic megacolon, or any other manifestation that might require colonic surgery while enrolled in the study * Presence of a stoma * Presence or history of a fistula * Colonic resection within 24 weeks before baseline or any other intra-abdominal or other major surgery performed within 12 weeks before baseline * History of extensive colonic resection (that is, less than \[\<\] 30 centimeter \[cm\] of colon remaining) or colonic resection that could impair the use of disease severity assessments (for example Mayo Score) to assess response to study intervention