A Study to Evaluate Upadacitinib in Adolescents and Adults With Moderate to Severe Atopic Dermatitis (Measure Up 2)

This study includes a 35-day screening period, a 16-week double-blind period, a blinded extension period up to Week 260, and a 30-day follow-up visit. Participants who meet eligibility criteria in the main study will be randomized in a 1:1:1 ratio to receive a daily oral dose of upadacitinib 30 mg or upadacitinib 15 mg or matching placebo. Upon completion of enrollment of a minimum of 810 participants in the main study, a supplemental study will continue to enroll adolescents (adolescent sub-study) until a total of 180 adolescent participants are enrolled overall (main study + adolescent sub-study). Randomization in the main study will be stratified by baseline disease severity (validated Investigator Global Assessment scale for Atopic Dermatitis \[vIGA-AD\] score of moderate \[3\] versus severe \[4\]), by geographic region (United States \[US\]/Puerto Rico/Canada, and Other), and by age (adolescent \[ages 12 to 17\] versus adult \[ages 18 to 75\]). The separate randomization for the adolescent sub-study will be stratified by baseline disease severity (moderate \[vIGA-AD = 3\] vs. severe \[vIGA-AD = 4\]) and by geographic region (US/Puerto Rico/Canada and Other). At Week 16 of the main study and the adolescent sub-study, participants in the placebo group will be re-randomized in a 1:1 ratio to receive daily oral doses of upadacitinib 30 mg or upadacitinib 15 mg in the blinded extension period. In the main study the re-randomization at Week 16 will be stratified by Week 16 50% improvement in Eczema Area and Severity Index \[EASI 50\] responder \[Yes/No\], geographic region \[US/Puerto Rico/Canada, and other\], and age group \[adolescent/adult\]. For the adolescent sub-study, the re-randomization will be stratified by EASI 50 responder (Yes/No) and by geographic region (US/Puerto Rico/Canada and Other). Participants originally randomized to upadacitinib will continue upadacitinib in the extension period at the same dose. Starting at the Week 4 visit, rescue treatment for AD may be provided at the discretion of the investigator if medically necessary. The Primary Analysis for the main study will be conducted after all ongoing participants have completed Week 16. In addition, a Primary Analysis for the adolescent population (including the adolescent participants from the main study and the adolescent sub-study) will be conducted after all ongoing adolescent participants have completed Week 16.