Rheumatology | February 12, 2021

Voyer TL, Gitiaux C, Authier FJ, Bodemer C, Melki I, Quartier P, Aeschlimann F, Isapof A, Herbeuval JP, Bondet V, Charuel JL, Frémond ML, Duffy D, Rodero MP and Bader-Meunier B

Rheumatology, keab116

DOI: https://doi.org/10.1093/rheumatology/keab116

Abstract

Objective
To evaluate the efficacy and safety of JAK inhibitors (JAKi) in juvenile dermatomyositis (JDM).

Methods
We conducted a single-center retrospective study of patients with JDM treated by JAKi with a follow-up of at least 6 months. Proportion of clinically inactive disease (CID) within six months of JAKi initiation was evaluated using PRINTO criteria and skin Disease Activity Score. Serum IFN-α concentration was measured by SIMOA assay.

Results
Nine refractory and one new-onset patients with JDM treated with ruxolitinib (n = 7) or baricitinib (n = 3) were included. The main indications for treatment were refractory muscle involvement (n = 8) and ulcerative skin disease (n = 2). CID was achieved in 5/10 patients (2/2 anti-MDA5, 3/4 anti-NXP2, 0/3 anti-TIF1γ positive patients) within six months of JAKi introduction. All responders could withdraw plasmatic exchange, immunoadsorption and other immunosuppressive drugs. The mean daily steroid dose decreased from 1.1 mg/Kg (range 0.35–2 mg/Kg/d) to 0.1 (range, 0–0.3, p= 0.008) in patients achieving CID, and was stopped in two. Serum IFN-α concentrations were elevated in all patients at the time of treatment initiation and normalized in both responder and non-responder. A muscle biopsy repeated in one patient 26 months after the initiation of JAKi, showed a complete restoration of muscle endomysial microvascular bed. Herpes zoster and skin abscesses developed in three and two patients, respectively.

Conclusion
JAKis resulted in a CID in a subset of new-onset or refractory patients with JDM and may dramatically reverse severe muscle vasculopathy. Overall tolerance was good except for a high rate of herpes zoster infection.