Rilonacept (IL-1 decoy receptor) efficacy in Schnitzler syndrome

Schnitzler syndrome (SchS) is a rare disease with suspected autoinflammatory background that shares several clinical symptoms, including urticarial rash, fever episodes, arthralgia, and bone and muscle pain with cryopyrin-associated periodic syndromes (CAPS). Cryopyrin-associated periodic syndromes respond to treatment with interleukin-1 antagonists, and single case reports of Schnitzler syndrome have shown improvement following treatment with the interleukin-1 blocker anakinra. This study evaluated the effects of the interleukin-1 antagonist rilonacept on the clinical signs and symptoms of SchS. Eight patients with SchS were included in this prospective, single-center, open-label study. After a 3-week baseline, patients received a subcutaneous loading dose of rilonacept 320 mg followed by weekly subcutaneous doses of 160 mg for up to 1 year. Efficacy was determined by patient-based daily health assessment forms, physician's global assessment (PGA), and measurement of inflammatory markers including C-reactive protein (CRP), serum amyloid A (SAA), and S100 calcium-binding protein A12 (S100A12). Treatment with rilonacept resulted in a rapid clinical response as demonstrated by significant reductions in daily health assessment scores and PGA scores compared with baseline levels (P < 0.05). These effects, which were accompanied by reductions in CRP and SAA, continued over the treatment duration. Rilonacept treatment was well tolerated. There were no treatment-related severe adverse events and no clinically significant changes in laboratory safety parameters. Rilonacept was effective and well tolerated in patients with SchS and may represent a promising potential therapeutic option.