Ravulizumab Versus Placebo in Adult Participants With Dermatomyositis

Open to people ages 18 years and up

• 18 years of age or older at the time of signing the informed consent.
• Body weight ≥ 30 kilograms at the time of Screening.
• Male or female.
• Diagnosis: Meet 2017 American College of Rheumatology/European League Against Rheumatism classification criteria for definite or probable DM.
• Participants who have an inadequate response or are intolerant to 1 or more DM treatments, including systemic corticosteroids or immunosuppressive/immunomodulatory therapies (for example, azathioprine, methotrexate, rituximab, intravenous immunoglobulin), either in combination or as monotherapy.
• Vaccinated against Neisseria meningitidis within 3 years prior to initiating ravulizumab as per national and local guidelines. Participants must receive the vaccination at least 2 weeks before first study intervention. The sponsor recommends that national and local guidelines for prophylactic antibiotics should also be followed.
• Female participants of childbearing potential and male participants must follow specified contraception guidance as described in the protocol.

• Participants who have been diagnosed with cancer within the last 3 years need to have appropriate negative cancer screening as per local standard of care within 6 months before Screening (basal or squamous cell skin cancer or carcinoma in situ of the cervix needs to have been excised and without evidence of residual disease for at least 3 months before Screening).
• Evidence of active malignant disease or malignancies diagnosed within the previous 3 years including hematological malignancies and solid tumors.
• Participants with other forms of myositis.
• As per investigator discretion, participants with significant muscle damage (for example, severe muscle atrophy, end stage muscle disease, MRI with severe atrophy or fibrofatty replacement)
• History of Neisseria meningitidis infection.
• Human immunodeficiency virus (HIV) infection (evidenced by HIV Type 1 or Type 2 antibody titer).
• Active systemic bacterial, viral, or fungal infection within 14 days prior to ravulizumab administration.
• Presence of fever ≥ 38°Celsius (100.4°Fahrenheit) within 7 days prior to study drug administration on Day 1.
• History of hypersensitivity to murine proteins or to 1 of the excipients of ravulizumab.
• Pregnant, breastfeeding, or intending to conceive during the course of the study.
• Inability or unwillingness to adhere to the protocol requirements.