ARCALYST

ARCALYST (rilonacept) is a biologic fusion protein that functions as an IL-1 cytokine trap, binding and neutralizing interleukin-1 alpha and beta to block their inflammatory signaling. It is approved for treating Cryopyrin-Associated Periodic Syndromes (CAPS)—including Familial Cold Autoinflammatory Syndrome and Muckle-Wells Syndrome—and recurrent pericarditis in adults. Rilonacept addresses the root cause of these rare autoinflammatory disorders by preventing excessive IL-1 activation that drives fever, rash, arthralgia, and other systemic inflammation. The drug represents a specialized niche therapy for genetically defined or IL-1-driven inflammatory conditions.