A Study to Assess the Efficacy and Safety of Risankizumab in Participants With Ulcerative Colitis

The purpose of this study is to evaluate safety and efficacy of risankizumab in participants with ulcerative colitis (UC) in participants who responded to induction treatment with risankizumab in a prior AbbVie study of risankizumab in UC. This study consists of three sub-studies and a Continuous Treatment Extension (CTE): Substudy 1 is a 52-week, randomized, double-blind, placebo-controlled maintenance study; Substudy 2 is 52-week, randomized, exploratory maintenance study; and Substudy 3 is an open-label long-term extension study for participants who completed Substudy 1 or 2, or participants who responded to induction treatment in Study M16-067 with no final endoscopy due to the Covid-19 pandemic or due to the geopolitical conflict in Ukraine and surrounding impacted regions. The CTE is an open-label extension for Substudy 3 completers to ensure continuous treatment with risankizumab until such time that risankizumab becomes commercially available and/or the subject can access treatment locally.