Therapy of polymyositis and dermatomyositis.

High-dose oral prednisone (at an initial dose of 1mg/kg/day) is the mainstay of therapy for PM/DM, and should be subsequently tapered slowly based on patients' clinical response. First-line combination of prednisone with intravenous immunoglobulins may be considered in patients with PM/DM-related severe systemic complications, especially in the subgroup exbititing life-threatening esophageal involvement. In patients who failed to respond to prednisone, the first-line immunosuppressive therapy includes methotrexate or azathioprine. Intravenous immunoglobulin therapy should be considered in patients in whom those cytotoxic drugs are contraindicated. In patients who failed to respond to prednisone, methotrexate or azathioprine, there is no general clinical consensus, although the options more often include: combined therapy of methotrexate and azathioprine, mycophenolate mofetil or rituximab. To date, TNF-α antagonists should not be considered in PM/DM patients, as both efficacy and safety concerns have been markedly raised in anti-TNF-α agent-treated PM/DM patients.