Treatment of steroid-resistant polymyositis and dermatomyositis

It is well known that a certain percentage of patients with polymyositis and dermatomyositis (PM/DM) is corticosteroid resistant. Established and novel approaches to steroid-resistant PM/DM are discussed in this review. Methotrexate (MTX) is a first-line treatment in the case that steroid therapy fails. Azathioprine and cyclophosphamide also fall into this category. Cyclosporine, a specific inhibitor of calcineurin, has been reported almost as effective as MTX. Tacrolimus, also a calcineurin inhibitor, and mycophenolate mofetil could be additional alternatives for the treatment. Several clinical trials have demonstrated that high-dose intravenous immunoglobulin is promising. Recently favorable data have been published using intravenous high-dose pulse cyclophosphamide or cyclosporine for the poorly prognostic interstitial pneumonitis or pulmonary fibrosis accompanied with PM/DM.