The efficacy of bariticinib in real-world patients with refractory or severe juvenile dermatomyositis:a monocentric retrospective study

Abstract Objective To evaluate the efficacy and safety of low dose baricitinib in children with refractory or severe juvenile dermatomyositis(JDM) in a real-world setting. Methods A monocentric retrospective real-world study was conducted, in which fourteen refractory and one severe newly diagnosed JDM patients were included. These patients were all treated by low dose baricitinib (below the recommended dose) combined with corticosteroids and or immunosuppressive agents. Clinical data were collected at the baseline and 4, 12, 24 weeks after baricitinib implication. Treatment response (complete response, CR, Partial response, PR and non-response,NR) was evaluated using both the Paediatric Rheumatology International Trials Organization (PRINTO) remission criteria and skin Disease Activity Score (DAS). All the adverse events (AEs) were recorded. Results After baricitinib treatment, all 15 patients showed improvement of skin involvement, including 14 patients with recurrent skin rashes and one newly diagnosed JDM. Calcinosis stabilized in two patients (2/3) and partially regressed in one. Four patients (4/15) had interstitial lung disease (ILD), which normalized in one, improved in two and stabilized in one. One patient complicated with macrophage activation syndrome (MAS) achieved clinical remission. CR was achieved in 3/15 patients, ranging from 4 to 12 weeks after baricitinib initiation. Five patients (5/15) got PR 4 to 24 weeks after baricitinib use. Daily steroid dosage was decreased from 0.632 mg/kg to 0.357 mg/kg (P = 0.043) at 24 weeks in all responders. However, there was no statistically difference in muscle improvement. One patient was stopped using baricitinib because of varicella zoster virus infection, while no other serious side effect was observed in this study. Conclusion Low dose baricitinib had efficacy and was safe to applied in refractory or severe JDM patients, especially for recurrent skin rashes. Baricitinib may also be helpful for JDM complicated with ILD and MAS.