Crohn's disease (CD) is a long-lasting condition causing swelling in the gut. This study wants to see if a new medicine, TAK-279, can help reduce this swelling. Participants will be given TAK-279 or a placebo (a fake treatment that looks like the real one) for 12 weeks to see if it reduces bowel inflammation and ulcers. An endoscopy (a test using a small camera to look inside the body) will check the bowel. Participants will continue taking TAK-279 for up to 52 weeks (1 year) and will have 15 clinic visits in total. The study involves 268 participants worldwide.

• The study lasts for about 60 weeks, including a 4-week follow-up.
• Participants are randomly assigned to receive one of three doses of TAK-279 or placebo.
• Eligibility includes adults 18-75 years old with moderate to severe CD.

Before joining, participants should know they must visit the clinic 15 times and be willing to take the medication for up to a year. They should also consider any risks or side effects that might occur.