This is a prospective, 12-week, open-label, single-arm study. The study population comprises individuals with refractory skin disease characteristic of dermatomyositis with no to minimal muscle involvement. After an up to 8-week Screening Period, eligible participants will receive brepocitinib 30 mg orally (PO) QD for 12 weeks.

Inclusion Criteria:

• A diagnosis of dermatomyositis according to 2017 EULAR/ACR Classification Criteria for Idiopathic Inflammatory Myopathies
• Active cutaneous manifestations of dermatomyositis
• Adult subjects (18-75 years old)
• Weight > 40 kg to < 130 kg, and with a body mass index (BMI) < 40 kg/m2.

Exclusion Criteria:

• 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