New therapies in anti-MDA5 antibody-positive dermatomyositis

This review focuses on treatments for anti-MDA5 antibody-positive dermatomyositis (MDA5-DM), which is a subgroup of dermatomyositis and characterized by frequent rapidly progressive interstitial lung disease and the high mortality rate. Despite conventional immunosuppressive therapies, there are still refractory cases. Newer treatment options are needed.The triple combination therapy (high-dose glucocorticoids, calcineurin inhibitor, and intravenous cyclophosphamide) improved patient survival compared to high-dose glucocorticoids and step-wise addition of the immunosuppressants. The triple therapy now has been widely used, but there are still refractory cases. In addition to the conventional-type immunosuppressants, recently the efficacy of Janus kinase inhibitors, biologic agents such as rituximab, plasma exchange, and polymyxin B perfusion for refractory MDA5-DM patients have been reported. However, the majority of those reports regarding new treatments are limited to case series, retrospective studies, and small single-arm studies. Adding antifibrotic drugs to immunosuppressive therapies might have some ancillary benefits.Several new therapies for MDA5-DM patients have emerged, although the optimal use of those therapies is still unknown. Further research and evidence accumulation will be needed. It is also noted that the intensive immunosuppressive therapies are associated with the higher infection risk.