Therapeutic Approaches in Myositis

Abstract

The inflammatory myopathies are a heterogeneous group of diseases including dermatomyositis, polymyositis, and inclusion body myositis. Few clinical trials have been conducted in myositis, making it difficult to provide clear recommendations on the treatment of these rare disorders. Although corticosteroids have not been tested in randomized controlled trials, the general expert consensus confirms their first-line use. However, in many patients, corticosteroid toxicity leads to significant disability, or these agents are ineffective, which then requires additional immunosuppression. Intravenous immunoglobulin is a reasonable short-term treatment with proven benefit in a controlled trial, but its long-term effectiveness remains unknown. The evidence for other immunosuppressive therapies has been derived mainly from case reports and open studies. These agents include methotrexate and/or azathioprine, followed by cyclosporine or tacrolimus (particularly for antisynthetase antibody-positive patients) and mycophenolate mofetil (for refractory rash). Newer therapies (eg, rituximab) are encouraging, but results from the largest randomized controlled trial studying this agent are soon to follow. The balance of evidence suggests that immunosuppressive drugs are effective in dermatomyositis and polymyositis, although randomized controlled trials are lacking.

The Pulmonary Histopathology of Anti-KS Transfer RNA Synthetase Syndrome

“…With our specific interest in immune-mediated rheumatologic lung disease, using an expanded panel of autoantibodies that captures rare specificities often seen in myositis syndromes may be responsible for our identification of these UIP pattern cases. 5,18 Preliminary evidence suggests that early identification and treatment of ILD in the AS are associated with a higher response rate to steroids and prolonged life spans, including patients diagnosed with UIP, and the average survival time of 79 months in this study supports this view.…”

“…Whereas anti-Jo1 AS is often accompanied by active myositis, the non-anti-Jo1 AS syndromes tend to present with more indistinct clinical features, although they share a predilection for arthritis, episodic fever, mechanic's hands, and ILD. 1,[18][19][20] In fact, many of these syndromes present initially with ILD and without myositis, and frequently patients die of progressive pulmonary failure. 1,3,20 This report of 5 cases of ILD due to anti-KS autoantibodies highlights the need to consider antisynthetase antibodies as a potential cause of pulmonary fibrosis, and to discourage simple screening using rheumatoid factor and anti-nuclear antibodies exclusively to establish an autoimmune etiology.…”

Current pharmacological treatment of idiopathic inflammatory myopathies

“…First-line therapy is invariably corticosteroids, [1, 3-7, 16, 17, 19-22, 24, 25] although there are no adequate randomized controlled trials to support this [3,6,9,13,17]. Other immunosupressives, notably azathioprine and methotrexate, are widely used as second-line agents in refractory cases or as steroid-sparing agents [1,3, 4, 6, 7, 9, 15, 16, 18-21, 25,26].…”

“…When a patient with DM or PM is not responding to immunosuppressive treatment, physicians must not be afraid to ask themselves if the diagnosis is wrong [3,6,15,16], before considering other therapeutic options [6,15,16].…”

A randomized controlled trial of methotrexate for patients with generalized myasthenia gravis

“…[6][7][8][9] The potential advantages of MTX include oral weekly dosing, a moderate side effect profile, and inexpensive generic preparations. Prior uncontrolled studies of MTX in MG suggested that MTX reduced symptoms or decreased corticosteroid dose in 38%-87% of patients.…”