Successful management with Janus kinase inhibitor tofacitinib in refractory juvenile dermatomyositis: a pilot study and literature review.

Objectives: JDM is a rare autoimmune inflammatory muscle disease with a pronounced IFN signature. Treatment for children with JDM has improved over the years with the use of steroids and immunosuppressive agents. However, there remains a subset of children who have refractory disease. Janus kinase and type I IFN signalling production are suspected to contribute to the pathogenesis of JDM. Our pilot study investigated the use of tofacitinib, a Janus kinase inhibitor, in refractory JDM cases to provide new therapeutic options for better treatment.

Methods: Refractory JDM was defined as patients who failed two or more steroid sparing agents or high-dose steroids. Tofacitinib was given to three refractory JDM patients with a dose of 5 mg twice per day for at least 6 months. Core set measures defined by Pediatric Rheumatology International Trials Organization were evaluated at month 0, 3 and 6 along with other systemic evaluations. A literature review was conducted to identify all the cases using Janus kinase inhibitors in JDM.

Results: All three subjects tolerated and responded well to tofacitinib with significant improvement in Child Myositis Assessment Scale, manual muscle testing-8, physician global disease activity and inflammatory indices without occurrence of severe adverse events.

Conclusion: This pilot study showed improvement of muscle strength, resolution of cutaneous lesions, increased daily quality of life and successful tapering of steroids when tofacitinib used in selected cases. Tofacitinib can be considered with caution when treating refractory JDM cases. Further randomized controlled trials are warranted to assess its efficacy in JDM.