UAB - Center for Clinical and Translational Science

for Patients with Skin Predominant Activity: - Must have CDASI Activity score of greater than or equal to 14, and have failed at least 1 standard of care systemic treatment, (eg, corticosteroids). - Confirmation of DM by the investigator and two of the following: 1. Gottron's papules; 2. Gottron's sign; 3. Heliotrope eruption; 4. Nailfold changes, (dilated capillary loops, capillary dropout, cuticular hypertrophy and/or rugged cuticles; 5. Photodistributed violaceous erythema, (skin that is exposed to sunlight and appears purplish/reddish, and patchy in appearance; 6. Positive DM serology - - Post DM diagnosis; standard of care workup for DM must have been completed prior to entry into this research study. - Willing to provide 8 biopsies during the course of the research study Inclusion Criteria for Patients with Muscle Predominant Activity: - MMT-8 ≤136/150 and PhGA, VAS ≥3 cm (0-10 cm) by visual analog scale (VAS) - Sum of PhGA, VAS, PtGA, and extramuscular global assessment VAS scores is ≥10 cm (0-10 cm) VAS for each. - Participant has failed at least two or more adequate courses of an immunosuppressive agent or immunomodulatory agent, including IVIG, at a dose known to be effective for rheumatologic diseases.

for Patients with Skin Predominant Activity: - Investigator site staff or members of their family. - Acute and Chronic present medical conditions - Intake of greater than 15 mg of prednisone or equivalent per day - Pregnant or breastfeeding females. Fertile men and women who will not comply with the use of 2 effective birth control methods as per the research protocol - Have required management of acute or chronic infections - Have pre existing demyelinating disorder such as multiple sclerosis, or other severe neurological deficits. - Clinically significant lab abnormalities - Any health condition that may be worsened by immunosuppression Exclusion Criteria for Patients with Muscle Predominant Activity: Similar to patients with skin predominant activity; Intake of >20 mg oral prednisone/day, or equivalent