A Study of the Efficacy and Safety of Risankizumab in Participants With Crohn's Disease

The study consists of 4 sub-studies, as follows: * Sub-study 1 (Randomized, double-blind, placebo controlled study) to evaluate the efficacy and safety of risankizumab versus placebo as maintenance therapy in participants with moderately to severely active Crohn's disease (CD) who responded to intravenous risankizumab induction treatment in Study M16-006 or Study M15-991; * Sub-study 2 (Randomized, exploratory maintenance study) to evaluate the efficacy and safety of two different dosing regimens for risankizumab as maintenance therapy in participants who responded to induction treatment in Study M16-006 or Study M15-991; * Sub-study 3 (Open-label, long-term extension study) to evaluate long-term safety of risankizumab in participants who completed Sub-study 1, Sub-study 2, another AbbVie risankizumab Crohn's disease study, or participants who responded to induction treatment in Study M16-006 or Study M15-991 with no final endoscopy due to the Covid-19 pandemic. Additional objectives are to further investigate long-term efficacy and tolerability of risankizumab; * Sub-study 4 (Open-label On Body Injector (OBI) administration and long-term extension study) to evaluate patient-reported outcomes, efficacy, safety, tolerability, and pharmacokinetics of risankizumab administered via OBI in participants who are receiving maintenance treatment with risankizumab. * OL CTE to ensure uninterrupted care in accordance with local regulations until risankizumab is commercially available for participants who completed Sub-study 3, Sub-study 4.

Inclusion Criteria: * Participants who have entered and completed Study M16-006 or Study M15-991 or other AbbVie risankizumab Crohn's disease study. * Participants have completed the study M16-006 or M15-991 and have achieved clinical response. * Sub-Study 4: * Participants receiving maintenance treatment in Sub-study 3 and willing to comply with the requirements of Sub-study 4, including self-administration of sub-cutaneous injections using the on-body injector (OBI). * Participant has received at least 16 weeks of stable dosing with risankizumab in Sub-study 3 (i.e., no rescue within 16 weeks and participant has surpassed the 72-week mark). Exclusion Criteria: * Participants should not be enrolled in Study M16-000 with high grade colonic dysplasia or colon cancer identified during Study M15-991, Study M16-006 or another AbbVie risankizumab Crohn's disease study if the final endoscopy was performed prior to enter Study M16-000 OR is considered by the Investigator, for any reason, to be an unsuitable candidate for the study. * Participant who has a known hypersensitivity to risankizumab or the excipients of any of the study drugs or the ingredients of Chinese hamster ovary (CHO), OR had an adverse event (AE) during Studies M16-006, M15-991 or another AbbVie risankizumab Crohn's disease study that in the Investigator's judgment makes the participant unsuitable for this study. * Participant is not in compliance with prior and concomitant medication requirements throughout Studies M16-006, M15-991 or another AbbVie risankizumab Crohn's disease study. * Confirmed positive urine pregnancy test at the Final Visit of Study M16-006, Study M15-991 or another AbbVie risankizumab Crohn's disease study. * Have a known history of lymphoproliferative disease, including lymphoma, or signs and symptoms suggestive of possible lymphoproliferative disease, such as lymphadenopathy and/or splenomegaly. * Any active or chronic recurring infections based on the Investigator's assessment makes the participant an unsuitable candidate for the study.