A Study to Investigate the Efficacy and Safety of Brepocitinib in Adults With Dermatomyositis

Open to people ages 18-75

• A diagnosis of dermatomyositis according to 2017 EULAR/ACR Classification Criteria for Idiopathic Inflammatory Myopathies
• Adult subjects (18-75 years old)
• Active muscle and skin disease at screening and baseline
• Prior therapy OR current therapy with corticosteroids, hydroxychloroquine, and/or one non-steroid immunosuppressant
• Weight > 40 kg to < 130 kg, and with a body mass index (BMI) < 40 kg/m2.

• Dermatomyositis with end-stage organ involvement
• Dermatomyositis with irreversible muscle involvement
• History of:
  • Any lymphoproliferative disorder
  • Active malignancy;
  • History of cancer within 5 years prior to randomization (exceptions for basal cell carcinoma, squamous cell carcinoma, ductal carcinoma in situ of the breast, carcinoma in situ of the uterine cervix, or thyroid carcinoma.)
  • Cancer-associated dermatomyositis
• Overlap myositis/connective tissue disease (except for overlap with Sjögren's syndrome)
• Participants at a risk of thrombosis or cardiovascular disease
• Participants with a high risk for herpes zoster reactivation
• Participants with active or recent infections