Effectiveness of Canakinumab for First‐Line Steroid‐Free Treatment in Systemic‐Onset Juvenile Idiopathic Arthritis and Juvenile Still Disease

OBJECTIVE: This prospective study assesses the response to canakinumab monotherapy administered as three monthly subcutaneous injections in glucocorticoid-naïve patients with newly diagnosed systemic juvenile idiopathic arthritis (sJIA) and Still disease and evaluates the durability of drug-free inactive disease for up to nine months after canakinumab cessation. METHODS: In a multicenter, two-phase open-label study of newly diagnosed sJIA or Still disease, canakinumab was administered at 4 mg/kg subcutaneously every 4 weeks for 12 weeks. Thereafter, patients were followed for an additional 40 weeks. Routine care was provided to nonresponders. RESULTS: In total, 21 patients were recruited, and 1 was excluded due to protocol violations. Fever resolved immediately in 17/19 patients. Two nonresponders (n = 2) were managed with different strategies: one received steroids alone, and the other received steroids plus canakinumab as part of routine care. By week 12, 14 patients achieved inactive disease. Thereafter, two flares occurred at weeks 24 and 36. Macrophage activation syndrome (MAS) was diagnosed in a third patient at week 19 and responded to treatment with glucocorticoids and cyclosporine A. By week 52, 11 patients had reached drug-free inactive disease and 3 had minimal disease activity. A total of 97 adverse events were reported; four were serious (one MAS, two disease flares, and one viral infection), but none were attributed to the study drug. CONCLUSION: Canakinumab steroid-free first-line therapy in newly diagnosed sJIA induces long-lasting, drug-free inactive disease in a substantial proportion of patients. Discontinuation of canakinumab was associated with disease flares in a minority of patients.