The US FDA has approved brepocitinib (Lisraya) for the treatment of dermatomyositis in adults. Brepocitinib is a Janus kinase (JAK) and tyrosine kinase 2 (TYK2) inhibitor. However its precise mechanism of action in dermatomyositis has not been fully established.

Clinical evidence The efficacy of brepocitinib was evaluated in a phase 3 clinical trial involving 241 patient and using the Total Improvement Score (TIS), a composite measure of myositis improvement based on Physician Global Assessment, Patient Global Assessment, Manual Muscle Testing of 8 Muscles, Extramuscular Global Assessment, Health Assessment Questionnaire – Disability Index, and muscle enzyme levels. At week 52, 82% of patients receiving brepocitinib achieved a TIS ≥20 compared with 63% of those receiving placebo. Similarly, 48% of patients in the brepocitinib group achieved a TIS ≥60 compared with 26% in the placebo…