Treatment of inflammatory myopathy: emerging therapies and therapeutic targets

Abstract

Despite the lack of placebo-controlled trials, glucocorticoids are considered the mainstay of initial treatment for idiopathic inflammatory myopathy and myositis-associated interstitial lung disease. Glucocorticoid-sparing agents are often given concomitantly with other immunosuppressive agents, particularly in patients with moderate or severe disease. First-line conventional immunosuppressive drugs include either methotrexate or azathioprine, and when they fail, more aggressive therapy includes mycophenolate mofetil, tacrolimus or cyclosporine, intravenous immunoglobulin, rituximab, or cyclophosphamide, used alone or in various combinations. Further investigations are required to assess the role of more novel therapies in the treatment of myositis and myositis-associated interstitial lung disease.

Keywords: dermatomyositis; idiopathic inflammatory myopathy; myositis; polymyositis; treatment.

Figure 1. Therapeutic approach to inflammatory myopathy

^†For the initial treatment of severe disease (marked weakness, dysphagia or rapidly progressive ILD), consider pulse intravenous methylprednisolone (1 g daily for three consecutive days) before oral or intravenous GC therapy. ^‡For patients on combination of high-dose GC plus another immunosuppressive agent, add prophylaxis against Pneumocystis jirovecii (e.g., trimethoprim–sulfamethoxazole double strength [160 mg/800 mg] three-times weekly). ^§Duration of therapy with GC-sparing agents may be extended to 1–2 years based on clinical response. ACTH: Adrenocorticotropic hormone; BIPAP: Bilevel positive airway pressure; GC: Glucocorticoid; ILD: Interstitial lung disease; IVIg: Intravenous immunoglobulin.