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 (NCT01045772 [ClinicalTrials.gov Identifier]; EudraCT #2006‐004290‐97).