Study of IFN-K in Dermatomyositis

Inclusion Criteria: * Patient newly diagnosed or relapsing with "definite" or "probable" dermatomyositis based on ENMC criteria (2004) * Patient requiring corticosteroids (CS) at a dose of 1 mg/Kg and ≤ 70 mg of prednisone equivalent/day or currently receiving CS at a dose of 1 mg/Kg and ≤ 70 mg of prednisone equivalent/day * Is a male or female, aged between 18 and 65 years, inclusive, at the time of the screening visit * study patient and his/her partner of child bearing potential has to use effective method of contraception Exclusion Criteria: * Is high-risk human papilloma virus (HPV) positive by (RT-PCR) on a cervical swab * Has cytological abnormalities ≥ HSIL on a cervical swab * Is positive for autoantibodies anti-NXP2, TIF1ɤ, MDA5 associated with severe pulmonary disease or anti-synthetase antibodies * Is positive for any malignancy or has a history of any malignancy * Has received IV pulse dose CS (≥ 250 mg prednisone equivalent/day) * Has received intravenous immunoglobulin (IVIg) * Has received potent immunosuppressive drugs such as cyclophosphamide, methotrexate, azathioprine, mycophenolate, cyclosporine A, oral tacrolimus * Has received abatacept, anifrolumab, belimumab, TNF antagonists or another registered or investigational biological therapy * Has received anti-B-cell therapy (e.g. rituximab, epratuzumab) * Has received any live vaccine * Has used any investigational or non-registered product , or any investigational or non-registered vaccine * Has inflammatory joint or skin disease other than dermatomyositis that may interfere with study assessments * Has frequent recurrences of oral or genital herpes simplex lesions * Is at high risk of significant infection and/or has any current signs or symptoms of infection at entry or has received intravenous antibiotics