Refractory Dermatomyositis Treated With Anifrolumab: Clinical Response and Dynamics of Type-I Interferon Signature.

Dermatomyositis (DM) is a systemic inflammatory disease predominantly affecting the skin and muscles, with potential involvement of internal organs. Despite multiple therapeutic options, treatment response may be unsatisfactory. Type-I interferon (IFN) signaling pathways have been proposed as key drivers of disease pathogenesis. Consequently, treatment with anifrolumab, a monoclonal antibody targeting IFN receptor-1, may offer therapeutic benefit. To date, only a few cases of refractory DM successfully treated with anifrolumab have been reported. We present two cases of refractory DM treated with anifrolumab achieving an almost complete cutaneous response. Longitudinal evaluation of the type-I IFN signature revealed a decrease during treatment. These findings support the hypothesis that type-I IFN plays a pathogenic role in DM, especially in patients with refractory disease. In this context, we aim to highlight the importance of considering anifrolumab as a therapeutic option and underscore the potential of the IFN signature as a biomarker of treatment response.