Subcutaneous Immunoglobulin (Hizentra) in Patients With Dermatomyositis: A Proof of Concept Study

Inclusion Criteria: 1. Men or woman aged \>18 years 2. Diagnosis of DM based on standard criteria 3. Receiving the equivalent of at least 0.4 g/kg IVIg every 4 weeks (IVIg group only) 4. Established response to IVIg or dependence on IVIg to maintain status established either by symptomatic worsening of condition at the end of the inter-dose interval for both groups or by worsening after reduction of the dose within the previous 12 months (IVIg group only) 5. IVIg regimen stable for 12 weeks while on IVIg (minor changes are permitted provided that the dose change is 15% or less) (IVIg group only) 6. Stable dosing with steroids and/or other immunosuppressives for 12 weeks with no changes schedule or intended. Exclusion Criteria: 1. Pregnancy, planned pregnancy, breast feeding or unwillingness to practice contraception 2. Severe concurrent medical conditions which would prevent treatment or assessment, including significant hematological, renal or liver dysfunction or malignancies 3. Initiation or immunomodulatory treatment other than IVIg in the past 24 weeks or modification of immunomodulatory treatment other than IVIg in the past 12 weeks. 4. Participation in trial of an investigational medicinal product in the past 12 weeks 5. Presence of skin infection unrelated to dermatomyositis, severe skin involvement Presence of any other medical condition, which in the opinion of the investigator might interfere with performance or interpretation of this study.