Part A (phase 2) will last up to 18 weeks and will enroll a maximum of 48 participants. Part A includes up to 9 visits that will be conducted at the research center, at home if allowed and available, or over the phone. Participants will be placed into 1 of 4 cohorts based on their age and weight and will receive a dosage of atumelnant between 6 mg and 80 mg, which will be taken orally once daily in the morning. All participants will remain on their pre-study GC therapies.
Part B (phase 3) will last up to 38 weeks and will enroll approximately 105 new participants. Part B includes up to 16 visits that will be conducted at the research center, at home if allowed and available, or over the phone. Participants will be randomized 2:1 to receive either atumelnant or placebo, which will be taken orally once daily in the morning. The dose level of atumelnant will be based on the results of Part A. All participants will remain on their pre-study GC therapies. However, the dose level of these GC therapies will be adjusted during specific time points in the study based on biomarkers and clinical presentation of the participants.
Part C (OLE) will last up to 5 years and will enroll up to 153 participants who completed either Part A or Part B. Part C includes up to 30 visits. The exact number of visits will depend on if participants were enrolled in Part A or Part B previously, and will be conducted at the research center, at home if allowed and available, or over the phone. All participants will receive atumelnant, which will be taken orally once daily in the morning. All participants will remain on their GC therapies. However, the dose level of these GC therapies may be adjusted based on biomarkers and clinical presentation of the participants.