A 12-Week Open-Label Study to Investigate the Efficacy and Safety of Brepocitinib in Adults With Skin-Predominant Dermatomyositis

Inclusion Criteria:

• A diagnosis of dermatomyositis according to 2017 EULAR/ACR Classification Criteriafor 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 cellcarcinoma, squamous cell carcinoma, ductal carcinoma in situ of the breast,carcinoma in situ of the uterine cervix, or thyroid carcinoma.) Cancer-associateddermatomyositis

• Overlap myositis/connective tissue disease (except for overlap with Sjögren'ssyndrome)

• Participants at a risk of thrombosis or cardiovascular disease

• Participants with a high risk for herpes zoster reactivation

• Participants with active or recent infections