This study includes a screening period of up to 35 days, a 16-week double-blind treatment period (Period A), and a 36-week double-blind treatment period (Period B).
Participants who meet eligibility criteria will be randomized at Baseline in a 2:2:1 ratio to one of 3 treatment groups: (1) risankizumab 150 mg, (2) risankizumab 300 mg, or (3) matching placebo. Randomization will be stratified by Baseline disease severity (Validated Investigator Global Assessment scale for Atopic Dermatitis \[vIGA-AD\] score of moderate \[3\] versus severe \[4\]) and geographic region (Japan versus rest of world).
At Week 16, participants in the placebo group will be re-randomized in a 1:1 ratio to receive either risankizumab 150 mg or 300 mg for the remainder of the study. Participants originally randomized to the risankizumab 150 mg or 300 mg arms will stay on their previously-assigned treatment through the end of the study.
