Acthar in Treatment of Refractory Dermatomyositis and Polymyositis

Inclusion Criteria: * Definite or probable polymyositis (PM) or dermatomyositis (DM) by Bohan and Peter criteria. * PM patients must either possess a myositis-associated autoantibody or undergo adjudication for confirmation of the PM diagnosis by consensus of two experts to ensure non-PM patients are not enrolled. This step is necessary since there are well-known mimics of PM. * Age ≥ 18 years. * Active myositis as defined by baseline Manual Muscle Testing (MMT-8) no greater than 125/150 and at least 2 additional CSM meeting the criteria stipulated below: 1. Patient global with a minimum value of 2.0 cm on a 10 cm visual analog scale(VAS) 2. Physician global with a minimum value of 2.0 cm on a 10 cm VAS scale 3. Health Assessment Questionnaire (HAQ) disability index with a minimum value of 0.25 4. Elevation of at least one of the muscle enzymes \[which includes creatine kinase (CK), aldolase, lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST)\] at a minimum level of 1.3 x the upper limit of normal. 5. Global extramuscular disease activity score with a minimum value of 1.0 cm on a 10 cm VAS scale \[this measure is the physician's composite evaluation and is based on assessments of activity scores on the constitutional, cutaneous, skeletal, gastrointestinal, pulmonary and cardiac scales of the Myositis Disease Activity Assessment Tool (MDAAT)\]. * To ensure that we can enroll active DM patients with a severe rash who may not meet the MMT-8 criterion noted above, we propose additional enrollment criteria such that the International Myositis Assessment and Clinical Studies (IMACS) definition of improvement (DOI) can potentially be met: 1. Cutaneous VAS score on MDAAT \> 3 cm on a 10 cm VAS scale, and 2. At least 3 of the above 5 (a through e under 4.) criteria. * Refractory myositis is defined by active disease despite an adequate glucocorticoid trial (\> 2 months of usual glucocorticoid therapy or intolerance to such therapy) and/or ≥ 1 conventional immunosuppressive agent (e.g. methotrexate, azathioprine, tacrolimus, cyclosporine, mycophenolate mofetil, IVIG, anti-TNF or rituximab) for a reasonable dose and duration (\> 3 months or intolerance to therapy). It is recommended to enroll refractory patients failing (or intolerant to) both glucocorticoids and at least 1 conventional immunosuppressive agent. * If the enrolling physician is planning to continue current immunosuppressive agents or glucocorticoids as concomitant therapy with Acthar gel during the trial, then patient must be on a stable glucocorticoid and/or immunosuppressive dose 2 weeks prior to visit 1. The patient should have been on that immunosuppressive medication for at least 8 weeks (and at least 4 weeks for glucocorticoids) prior to visit 1. * If the enrolling physician is planning to discontinue current immunosuppressive agent or glucocorticoids, then following wash out period is required prior to visit 1. * If previous concomitant medications were discontinued, the following wash out periods are required prior to Visit 1 * Methotrexate -4 weeks * Other IS agent (e.g. azathioprine, cyclosporine, tacrolimus, leflunomide, mycophenolate mofetil) - 4 weeks * IVIg or cyclophosphamide - 2 months * rituximab -6 months * infliximab or adalimumab -8 weeks * glucocorticoids - 2 weeks * etanercept -2 weeks * anakinra -1 week Exclusion Criteria: * Juvenile DM or PM, myositis in overlap with another connective tissue disease, cancer associated myositis, inclusion body myositis, or any other non immune-mediated myopathy. * Hypersensitivity to Acthar * Severe cardiac or pulmonary involvement * Severe muscle damage defined as a baseline global muscle damage score on the MDI (Myositis Damage Index) of ≥ 5 cm on a 10 cm VAS. * Patients with malignancy within 3 years of screening (except basal cell cancer or squamous cell cancer of skin). * Uncontrolled diabetes, hepatic or renal disease. * Ongoing active or chronic infections. * Pregnant or lactating females. * For any medical or physical or socio-psychological reasons that PI feels would not allow the subject to complete the study.