Anakinra in Systemic-onset Juvenile Idiopathic Arthritis

Background: Systemic-Onset Juvenile Idiopathic Arthritis (SJIA) is a rare disease associated with dysregulated interleukin (IL)-1 activity. Objectives: To assess the efficacy and safety of Anakinra, an IL-1 receptor antagonist in SJIA and its effects on gene expression profiling. Methods: We conducted a multicenter, randomized, double-blind placebo-controlled trial. The primary objective was to compare the efficacy of a one-month treatment with anakinra (2 mg/kg subcutaneoulsy daily, maximum 100 mg) to a placebo between 2 groups of 12 SJIA patients each. Response was defined by a 30% improvement of the pediatric American College of Rheumatology criteria for JIA, resolution of systemic symptoms and a decrease of at least 50% of both C-reactive protein and erythrocyte sedimentation rate compared to baseline. An intention-to-treat analyze was performed. After Month 1 (M1), patients taking placebo were switched to Anakinra. Secondary objectives included tolerance and efficacy assessment for 12 months. Results: At M1, concluding the randomized trial, there was a significant difference in the response rate between patients treated with Anakinra (8/12 responders) and placebo (1/12) (p=0.003). The number of adverse events, mainly pain to injections, was similar between both groups. Ten patients from the placebo group switched to Anakinra at M1; nine were responders at M2. Between M1 and M12, six patients stopped treatment for an adverse event (Crohn’s disease, hepatitis), a lack of efficacy or a disease flare (2 cases each). Blood gene expression profiling at enrollment and upon follow-up allowed us to identify one set of dysregulated genes that reverted to normal values in the clinical responders and a second set, including interferon-inducible genes, that was induced by Anakinra. Conclusion: Anakinra is an effective treatment of SJIA. Its effect is associated with normalization of blood gene expression profiles in clinical responders and de novo induction of an interferon signature. (Clinical trials registration number: NCT00339157)