Crohn's disease (CD) is a condition that causes inflammation (redness and swelling) in the digestive tract, often affecting the bowels. Symptoms include tummy pain, diarrhea, tiredness, and losing weight. This study looks at how safe and effective a medicine called risankizumab, given as a shot under the skin (subcutaneous), is for treating adults with moderate to severe CD.

The study is divided into three parts: Period A, Period B, and Period C. In the beginning, participants will either get risankizumab or a placebo (a fake treatment). Depending on how they respond, they may get different doses of risankizumab or continue with a placebo in the following periods. In the last part, all eligible participants will receive risankizumab. There will be about 276 adult participants from around the world.

• The study lasts about 93 weeks, with up to 24 weeks for initial treatment and 52 weeks for follow-up.
• Participants must have moderate to severe CD diagnosed for at least 3 months.
• People with other bowel diseases or certain conditions can't join.