Rilonacept in the treatment of chronic inflammatory disorders

Rilonacept (IL-1 Trap/Arcalyst) is a long-acting interleukin-1 (IL-1) blocker developed by Regeneron Pharmaceuticals. Initially, Regeneron entered into a joint development effort with Novartis to develop rilonacept for the treatment of rheumatoid arthritis (RA) but this was discontinued following the review of phase II clinical data showing that IL-1 blockade appeared to have limited benefit in RA. In February 2008, Regeneron received Orphan Drug approval from the Food and Drug Administration for rilonacept in the treatment of two cryopyrin-associated periodic syndromes (CAPS) disorders, namely, familial cold-induced autoinflammatory syndrome (FCAS) and Muckle-Wells syndrome (MWS), for children and adults 12 years and older. CAPS is a group of inherited inflammatory disorders consisting of FCAS, MWS, neonatal-onset multisystem inflammatory disease (NOMID), also known as chronic infantile neurologic, cutaneous and articular (CINCA) syndrome, all associated with heterozygous mutations in the NLRP3 (CIAS1) gene, which encodes the protein NLRP3 or cryopyrin. Prior to the discovery of the NLRP3 (CIAS1) mutations and the advent of IL-1-targeted therapy, treatment was aimed at suppressing inflammation but with limited success. The dramatic success of selective blockade of IL-1beta, initially with the IL-1 receptor antagonist (IL-1Ra; Kineret(R) or anakinra/ Amgen, Inc.), not only provided supportive evidence for the role of IL-1beta in CAPS but also demonstrated the efficacy of targeting IL-1beta for treatment of these conditions. A high-affinity protein called rilonacept has been produced by cytokine Trap technology and was developed by Regeneron. The desirable longer half-life of rilonacept offers potential alternatives to patients who do not tolerate daily injections very well or have difficulty with drug compliance. The initial evidence for the beneficial effects of rilonacept for MWS and FCAS suggests that it would also be a suitable treatment for CNICA/NOMID. It is yet to be determined whether rilonacept would be an effective treatment for other chronic inflammatory conditions such as gout, familial Mediterranean fever and systemic juvenile idiopathic arthritis.