The main aim of this study is to learn if TAK-279 reduces bowel inflammation and symptoms compared to placebo. Another aim is to compare any medical problems that participants have when they take TAK-279 or placebo and how well the participants tolerate any problems.

The participants will take capsules of either TAK-279 or placebo for up to 3 months (12 weeks). Then all the participants will receive TAK-279 for the rest of the treatment part of the study (1 year or 52 weeks).

During the study, participants will visit their study clinic several times.

Study TAK-279-UC-2001 is a multicenter, randomized, placebo-controlled, study with a 12-week double-blinded induction treatment period, a 40-week open-label treatment period (52 total weeks of treatment), and a 4-week safety follow-up period.

An approximate total of eligible 207 participants will be randomized to one of the three treatment groups -

1. TAK-279 Dose 1
2. TAK-279 Dose 2
3. Placebo

The maximum study duration per participant is approximately 60 weeks, including up to 30 days for the screening period, a 12-week randomized and double-blinded induction treatment period, a 40-week open-label treatment period, and a 4-week safety follow-up period.

Inclusion Criteria:

1. Male or female aged 18-75 years old with diagnosis of UC for at least 30 days. In South Korea, the age requirement for adult participants is ≥19 years of age.
2. Confirmed diagnosis of moderately to severely active UC assessed by mMS and ES.
3. Participants with a history of inadequate response to, loss of response to, or intolerance to one or more of conventional, biologic or advance therapies for UC.
4. Participants must meet the contraception recommendations.

Exclusion Criteria:

1. Participants with indeterminate/unclassified inflammatory bowel disease (IBD), microscopic colitis, ischemic colitis, infectious colitis, radiation colitis, diverticular disease associated with colitis, and/or clinical/histologic findings suggestive of Crohn's disease (CD).
2. Participants with complications of UC such as strictures, stenoses, fistulas, short gut syndrome, or any other manifestation that might require surgery during the study.
3. Participants with a current ileostomy or colostomy. Participants who had a J-pouch are excluded, as a J-pouch could result in a stoma.
4. Participants who have failed 3 or more classes of advanced therapies.

Takeda provides access to the de-identified individual participant data (IPD) for eligible studies to aid qualified researchers in addressing legitimate scientific objectives (Takeda's data sharing commitment is available on https://clinicaltrials.takeda.com/takedas-commitment?commitment=5). These IPDs will be provided in a secure research environment following approval of a data sharing request, and under the terms of a data sharing agreement.

IPD from eligible studies will be shared with qualified researchers according to the criteria and process described on https://vivli.org/ourmember/takeda/. For approved requests, the researchers will be provided access to anonymized data (to respect patient privacy in line with applicable laws and regulations) and with information necessary to address the research objectives under the terms of a data sharing agreement.