Purpose of review: To review the treatment advances of the inflammatory myopathies, a heterogeneous group of diseases that includes polymyositis, dermatomyositis, and inclusion body myositis.
Recent findings: There are few clinical trials in myositis, making it difficult to provide clear recommendations on the treatment of these rare disorders. The current management for IIM includes the initial use of corticosteroids followed by various conventional second-line treatments such as methotrexate and azathioprine. Although these drugs have not been tested in rigorous randomized controlled trials, general expert consensus confirms their use. Intravenous immunoglobulin is a reasonable short-term treatment with proven benefit in one controlled trial, although the evidence for other immunosuppressive therapies has been derived mainly from uncontrolled studies. Cyclosporine or tacrolimus have shown efficacy in myositis including those patients with interstitial lung disease (ILD), whereas mycophenolate mofetil is effective in both polymyositis and refractory dermatomyosits (including recalcitrant rash) and ILD. Uncontrolled studies for rituximab are encouraging but results from the largest randomized controlled trial in myositis failed to meet the primary endpoint. Anti-tumor necrosis factor (TNF) agents have shown mixed results in small, randomized clinical trials with infliximab demonstrating no benefit and etanercept leading to encouraging results warranting further study. Some newer novel therapies such as ACTH analogues and tocilizumab require additional investigation.
Summary: The balance of evidence suggests that traditional immunosuppressive and immunomodulatory drugs are certainly effective in polymyositis and dermatomyositis despite the lack of randomized controlled trials. Newer therapies are being studied but no major breakthroughs have been realized.