Strong Argument: Recent Developments in Myositis Diagnosis & Care

Treatment

Dr. Christopher-Stine noted that identifying active disease domains (i.e., skin, muscle, lung or other) in individual patients makes the greatest difference in selecting the appropriate therapy to treat myositis. Treatment options include glucocorticoids, methotrexate, azathioprine, mycophenolate mofetil, rituximab and intravenous immunoglobulin (IVIG).

IVIG has received particular attention since the publication of the ProDERM study. In this study, patients with dermatomyositis on a stable dose of standard therapy (i.e., mycophenolate mofetil, methotrexate, glucocorticoids and/or hydroxychloroquine) were randomized to receive either 2 g/kg of IVIG or placebo every four weeks for 16 weeks. Patients who showed clinical deterioration in this period were switched to the alternative treatment and, at week 16, all patients on placebo and those without clinical deterioration on IVIG received 2 g/kg of IVIG every four weeks for 24 weeks. The study then measured the proportion of responders in each group with at least minimal improvement in the total improvement score (i.e., a composite response criteria) without deterioration at two consecutive visits up to week 16. Researchers found that 79% of patients receiving IVIG and 44% of patients receiving placebo met this end point, respectively.⁸

In 2021, largely based on these trial results, the U.S. Food & Drug Administration (FDA) approved IVIG for the treatment of adult dermatomyositis. A benefit of the approval has greater insurance coverage for the treatment. However, a downside is that insurance companies are now asking for biopsy proof of myositis even in patients with a clear clinical diagnosis.

In Sum

Dr. Christopher-Stine gave the audience a framework in which to evaluate and care for patients with idiopathic inflammatory myopathies.

Jason Liebowitz, MD, is an assistant professor of medicine in the Division of Rheumatology at Columbia University Vagelos College of Physicians and Surgeons, New York.

References

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8. Aggarwal R, Charles-Schoeman C, Schessl J, et al. Trial of intravenous immune globulin in dermatomyositis. N Engl J Med. 2022 Oct 6;387(14):1264–1278.