rilonacept

Rilonacept, sold under the brand name Arcalyst, is a recombinant fusion protein that acts as an interleukin-1 (IL-1) trap. It consists of the Fc region of human IgG1 fused to the extracellular domains of the IL-1 receptor and the IL-1 receptor accessory protein, enabling it to bind IL-1α and IL-1β with high affinity and prevent signaling through the IL-1 receptor.

Clinical use and indications: It is approved for the treatment of cryopyrin-associated periodic syndromes (CAPS), a group of autoinflammatory disorders. It has also been studied and approved in some regions for recurrent pericarditis. Rilonacept is typically considered for patients with CAPS or recurrent pericarditis who require ongoing IL-1 blockade or who do not tolerate other therapies.

Administration and dosing: The medication is administered by subcutaneous injection, with dosing customized to the indication and patient factors. Dosing schedules are determined by the prescribing clinician and may involve regular injections in outpatient settings, with monitoring for response and adverse effects.

Safety and precautions: Common adverse events include injection-site reactions, upper respiratory infections, and headache. There is a risk of serious infections due to immune modulation; caution is advised in patients with active infections or immunodeficiency. Immunizations should be up to date, and vaccines should be discussed with a clinician to determine suitability on an individual basis.

Regulatory status and overview: Rilonacept is approved in the United States for CAPS, and regulatory status for recurrent pericarditis varies by country. As a IF-1–blocking biologic, it is part of a broader class of IL-1 inhibitors used for autoinflammatory conditions and related disorders.