We present a case of refractory cutaneous dermatomyositis (DM) in a 51-year-old Hispanic female which failed multiple treatments but found symptomatic relief with anifrolumab. Anifrolumab was the only treatment that was associated with significant improvement in the rash and pruritis of the patient and lowered her corticosteroid needs. To our knowledge, this is the only second case report that has shown success in treating refractory cutaneous symptoms of DM with anifrolumab after failing standard and multiple combinations of therapies. Anifrolumab is a new first-in-class human monoclonal antibody, which inhibits type 1 interferon receptor (IFN-1) and is used to treat systemic lupus erythematosus (SLE). It is FDA-approved for non-renal manifestations of SLE. This IFN pathway seems to be also active in patients with DM. The presence of IFN-1 and IFN-2 has been reported in muscle biopsies of patients with inflammatory myopathies. Moreover, the IFN activation signature is present in the muscle, blood, and skin of patients with DM. IFN-1 has been assumed to activate toll-like receptors which activate the dendritic cells leading to the secretion of cytokines and chemokines. This potential pathophysiological role of IFN in DM may explain the symptom improvement experienced by our patient after starting anifrolumab treatment. Anifrolumab has additionally been shown to have a good safety profile when used to treat patients with SLE with up to three years of treatment on background conventional disease-modifying antirheumatic drug (DMARD) therapies. In conclusion, SLE and DM share similarities in their pathophysiology and cutaneous disease involvement and can be differentiated clinically. Skin manifestations of DM can persist despite combinations of therapies even when weakness resolves. With this case report, we aim to highlight the possibility of utilizing anifrolumab for treating DM skin manifestations, especially in refractory cases. More research is needed to guide where anifrolumab stands in the therapeutic algorithm for DM. It is unknown whether it treats the myositis component, DM-related arthritis, or coexistent rheumatoid arthritis.
