Study Comparing Intravenous (IV)/Subcutaneous (SC) Risankizumab to IV/SC Ustekinumab to Assess Change in Crohn's Disease Activity Index (CDAI) in Adult Participants With Moderate to Severe Crohn's Disease (CD)

Crohn's disease (CD) is a long-lasting condition causing inflammation that can affect any part of the gut. This study will evaluate how well risankizumab works compared to ustekinumab. This study will assess change in Crohn's Disease Activity Index (CDAI). Risankizumab is an investigational drug being developed for the treatment of Crohn's Disease (CD). Ustekinumab is an approved drug for the treatment of moderate and severe CD. Participants are randomly assigned to one of the three treatment groups. Each group receives a different treatment. There is a 1 in 2 chance that participants will be assigned to ustekinumab. Around 508 adult participants with moderate to severe CD will be enrolled in approximately 307 sites worldwide. In Part 1, participants assigned to risankizumab will receive intravenous (IV) doses of risankizumab at Week 0, 4,8 and subcutaneous (SC) doses every 8 weeks thereafter through Week 48. Participants assigned to ustekinumab will receive intravenous (IV) dose of ustekinumab at Week 0 and subcutaneous (SC) doses every 8 weeks thereafter through Week 48. In Part 2, participants who received risankizumab in Part 1 and completed the Week 48 visit will continue to receive SC risankizumab for up to an additional 220 weeks. There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, checking for side effects and completing questionnaires.

Inclusion Criteria: * Confirmed diagnosis of Crohn's disease (CD) for at least 3 months prior to Baseline. * Crohn's disease activity index (CDAI) score 220 - 450 at Baseline. * Confirmed diagnosis of moderate to severe Crohn's Disease as assessed by stool frequency (SF), abdominal pain (AP) score, and Simple Endoscopic score for CD (SES-CD). * Demonstrated intolerance or inadequate response to one or more anti-tumor necrosis factor (TNF) therapies. Exclusion Criteria: * Current diagnosis of ulcerative colitis or indeterminate colitis. * Receipt of CD approved biologic agents prior to Baseline (as detailed in protocol), or any investigational biologic or other agent or procedure prior to Baseline (as detailed in protocol). * Prior exposure to p19 and/or p40 inhibitors (e.g., risankizumab and ustekinumab). * Currently know complications of CD (strictures, short bowel, etc).