The MIGHT Trial - An Exploratory Clinical Trial of IVIG in Anti-HMGCR Immune Mediated Necrotizing Myopathy

Inclusion Criteria:

• Age > 16 years

• Anti-HMGCR antibody positive

• MMT-8 score < 142 (range 0-160)

• Serum CK > 5x upper limit of normal

• Anti-HMGCR IMNM disease duration < 36 months at screening

• No moderate or severe respiratory or swallowing dysfunction due to anti-HMGCR IMNMat screening

• No history of dermatomyositis rash

• Must reside in a state with a participating research site

Exclusion Criteria:

• Oral glucocorticoid (GC) daily dose > 15mg at screening

• Change in oral GC dose < 2 weeks prior to screening

• Prior IVIG treatment for anti-HMGCR IMNM

->1 oral conventional synthetic DMARD (e.g. methotrexate, mycophenolate mofetil,azathioprine) use at screening

• Change in concomitant DMARD dose < 4 weeks prior to screening

• Rituximab < 6 months prior to screening

• Plasma exchange, cyclophosphamide, or biologic immunosuppressive medication < 3months prior to screening

• Use of statin medication at screening

• History of anaphylactic reaction to IVIG

• History of angina pectoris, myocardial infarction, transient ischemic attack, orstroke < 12 months prior to screening

• Females of child-bearing potential who are pregnant, breastfeeding, or are unwillingto practice a highly effective method of contraception during the study

• Wells Criteria for DVT score of 2 or more at screening

• Wells Criteria for PE score of 4 or more at screening

• Weight >120kg

• History of cancer (excluding non-melanomatous skin cancer) < 5 years prior toscreening

• History of pulmonary embolism or deep venous thromboembolism < 3 years prior toscreening

• History of hyperviscosity or hypercoagulable state

• Currently receiving anti-coagulation therapy (vitamin K antagonists, non-vitamin Koral anticoagulants [e.g. dabigatran, rivaroxaban, apixaban], parenteralanticoagulants [e.g. fondaparinux]. Note that oral anti-platelet agents are allowed (e.g. aspirin, clopidogrel, ticlopidine).

• Glomerular filtration rate (GFR) <60mL/min at the time of screening

• Any medical condition which, in the investigator's judgment, makes participation inthe clinical trial unadvisable or which would interfere with evaluation of the studytreatment.