Anifrolumab in Refractory Dermatomyositis and Antisynthetase Syndrome.

Dermatomyositis (DM) and antisynthetase syndrome are rare autoimmune disorders within the spectrum of inflammatory myopathies, typically characterized by cutaneous and muscular inflammation along with systemic manifestations. This case report highlights the evolving treatment strategies for inflammatory myopathies, with a focus on the use of anifrolumab, a type-1 interferon receptor blocker, in a 29 year-old female with refractory DM/antisynthetase syndrome. The patient presented with classic DM features, including heliotrope rash, Gottron's papules, and malar erythema, but lacked significant myopathy. Initial therapies with methotrexate and prednisone were ineffective, and her condition worsened despite adding intravenous immunoglobulin (IVIg) and tofacitinib. Following persistent disease progression, therapy was switched to a combination of IVIg, apremilast, and anifrolumab as an off-label drug for DM. Within 5 months, the patient showed significant improvement in myopathy and skin manifestations. Anifrolumab targets the interferon (IFN) axis, which plays a crucial role in DM pathogenesis. This case underscores the potential of targeted therapies like anifrolumab in managing DM, especially in cases not responsive to conventional standard of care therapies. It also highlights the need for further research into the IFN pathway as a therapeutic target in inflammatory myopathies. Trial Registration: ClinicalTrials.gov identifier: NCT06455449.