Pirfenidone in Progressive Interstitial Lung Disease Associated With Clinically Amyopathic Dermatomyositis

Interstitial lung disease (ILD) is a common complication of dermatomyositis (DM) with prevalence up to 65%, and is considered to be one of the determining factors of prognosis. Clinical amyopathic dermatomyositis (CADM), which is a special phenotype of DM, with characteristic cutaneous manifestations but no or only subclinical myopathy. Many studies, mainly from Asia, including ours, have demonstrated that these patients with CADM tend to develop a rapidly progressive ILD (RPILD) and have a poor response to conventional therapy, such as high-dose corticosteroids and immunosuppressants, leading to lethal outcome with a 6-month survival rate of less than 50%. Pirfenidone, a new oral antifibrotic agent, has been approved for the treatment of idiopathic pulmonary fibrosis (IPF). Randomized controlled trials of pirfenidone in patients with IPF suggested that it could ameliorate pulmonary function decline and improve the progression-free survival. Its utility in connective tissue disease (CTD) related ILD has been implicated, but no evidence has yet demonstrated its efficacy. Therefore, the investigators conduct this study to evaluate the possible therapeutic effects of pirfenidone on RPILD associated with CADM.