Experience with the use of mycophenolate mofetil in juvenile idiopathic inflammatory myopathies

Objective The objective of this study was to evaluate the efficacy and safety of MMF in juvenile idiopathic inflammatory myopathies (JIIMs). Methods Patients diagnosed with JIIM and treated with MMF enrolled in the Juvenile Dermatomyositis Research Group (JDRG) in the UK or followed at the Giannina Gaslini Institute in Genoa, Italy, were included. The following information was collected retrospectively at MMF initiation, at 3, 6 and 12 months after treatment start, and at last follow-up visit: clinical manifestations, laboratory data, physicians' subjective assessment of disease activity, standardized outcome measures of muscle strength/endurance, cutaneous disease activity, physical function, global disease activity, cumulative damage, and ongoing treatment. Results Of the 29 patients included, 23 had juvenile DM and 6 had overlap myositis. During administration of MMF, improvement in measures of muscle strength, skin disease activity, and overall disease activity was seen, with an increase in the frequency of normal scores for Manual Muscle Test-8 from 50.0% to 83.3%, Childhood Myositis Activity Score from 53.5% to 88.9%, muscle component of DAS from 55.2% to 84.2%, skin component of DAS from 31.0% to 42.1%, visual analogue scale for skin disease activity from 25.0% to 47.4%, and visual analogue scale for overall disease activity from 7.1% to 42.1%. The number of patients with inactive disease increased from 10.3% at baseline to 68.5% at last follow-up. CS dose was significantly reduced, from 0.3 to 0.1 mg/kg/day. No relevant side effects were reported. Conclusion Our experience suggests that MMF is a valuable therapeutic option for the management of JIIM.