A Study of Oral Upadacitinib Tablets to Assess Change in Disease State in Participants Aged 12-75 Years With Moderate to Severe Atopic Dermatitis in Brazil

Atopic Dermatitis (AD) is a chronic inflammatory skin disease that is characterized by intense itching, oozing and crusting, redness, skin erosion and dry skin. This study will evaluate how well upadacitinib compared to placebo (no medicine) works to treat participants with moderate to severe AD in Brazil. The study will assess change in disease signs and symptoms. Upadacitinib is an investigational drug being developed for the treatment of Atopic Dermatitis (AD). This study is "double-blinded", which means that neither the trial participants nor the study doctors will know who will be given which study drug. Study doctors put the participants into 1 of 4 groups called treatment arms. Each group receives a different treatment. Participants with a diagnosis of AD will be enrolled. Around 150 participants will be enrolled in the study in approximately 20 sites in Brazil. Participants will receive the following for up to 52 weeks: Participants will receive oral upadacitinib tablets once daily for up to week 52. Participants may also receive oral placebo tablets once daily up to week 16 followed by oral upadacitinib tablets once daily up to week 52. Arm 1: Upadacitinib Dose A up to week 52. Arm 2: Upadacitinib Dose B up to week 52. Arm 3: Placebo up to week 16 followed by upadacitinib Dose A up to week 52. Arm 4: Placebo up to week 16 followed by upadacitinib Dose B up to week 52. There may be higher burden for participants in this trial compared to their standard of care. Participants will attend monthly visits during the course of the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, and checking for side effects.