Myositis
Abstract Number 1700 - Mycophenolate Mofetil (MMF) in Juvenile Dermatomyositis
AUTHORS: Kelly A. Rouster-Stevens, Lauren M. Pachman. CMH, Northwestern University, Feinberg School of Medicine, Chicago, IL
PURPOSE: Because of the potential overlap in disease pathogenesis between JDM and SLE, this study evaluated the utility of MMF (Cellcept) in children with JDM.
Juvenile dermatomyositis (JDM) is a systemic inflammatory myopathy primarily affecting skeletal muscle and skin. The pathophysiology is unknown, but evidence of a Type I interferon response was demonstrated in gene expression analysis of muscle biopsies from untreated patients with JDM. Type I interferon has also been implicated in the development of systemic lupus erythematosus (SLE). Mycophenolate mofetil (MMF), a selective suppressor of T and B lymphocyte proliferation, has been successful in the treatment of SLE patients. Because of the potential overlap in disease pathogenesis between JDM and SLE, this study evaluated the utility of MMF in children with JDM.
METHODS: This was a retrospective chart review of 7 pediatric patients with definite JDM treated with MMF for a minimum of 3 months. The children received MMF for continued disease activity despite immunosuppressive therapy. A validated Disease Activity Score (DAS), which generates subscores for skin and muscle, was utilized to assess JDM activity at the onset of MMF and at most recent follow-up. Data on demographics, MMF dose and side effects, and DAS was collected.
RESULTS: The 7 patients (6 girls, 1 boy; 4 Caucasian, 3 non-Caucasian) identified had an average age of 12.5 ± 4.0 years (range 7.1 - 16.5) at the start of MMF. Patients had been on other immunosuppressive agents, including methylprednisolone, prednisone, methotrexate, and cyclosporine, for a mean of 5.4 ± 4.0 years (range 1.0 - 11.3). At the time of most recent follow-up, the average duration of MMF therapy was 10.5 ± 9.2 months (range 3.0 - 29.2) and dose of MMF was 25.7 ± 10.5 mg/kg/day (range 12 - 39). No patient developed leukopenia or gastrointestinal complications while on MMF. The most common side effect was infection, occurring in 6 of the 7 patients. However, all infections were mild viral upper respiratory infections except one patient who required antibiotics for an uncomplicated sinusitis. Mean total DAS, skin subscore, and muscle subscore at most recent follow-up were decreased compared to initiation of MMF.
Mean DAS ± SD (range) |
Initiation of MMF | Most recent f/u on MMF |
| Total | 9.4 ± 4.3 (2 - 15) | 4.3 ± 2.3 (1 - 7) |
| Skin | 4.9 ± 2.8 (1 - 8) | 2.6 ± 2.6 (0 - 7) |
| Muscle | 4.5 ± 3.1 (0 - 8) | 1.7 ± 2 (0 - 5) |
CONCLSUION: This study suggests MMF is an alternative therapy for children with JDM and may decrease disease activity. MMF appears to be well tolerated, but patients require close monitoring for infection. Further studies in pediatric patients need to be performed to establish the use of this immunosuppressive agent in children with JDM.
COMMENT: Other than prednisone, there are no FDA-approved therapies for the treatment of myositis in the adult or juvenile type. Most therapies are “borrowed” from other autoimmune disease treatments regimens. Anti-rejection drugs often used in solid organ transplantation have become increasingly popular agents for immune suppression in systemic inflammatory disease. Although limited by the study design (retrospective chart review), the data from this study suggests that MMF is well tolerated and efficacious in the JDM population with relatively mild infectious side effects. Ideally, we need to conduct well-designed randomized head-to-head trials with two different immunosuppressive regimens or prednisone alone vs. prednsione plus an additional immunosuppressive agent (as placebo-controlled trials may be unethical, owing to the known benefit of corticosteroids therapy).
