Box 1 | Market for CAPS

Analysing the market for therapies for cryopyrin-associated periodic syndromes (CAPS) is Uma Yasothan, Senior Consultant, IMS Health, London, UK.

The incidence of CAPS, a group of very rare, inherited, autoinflammatory conditions, has been reported to be approximately 1 in 1,000,000 in the US, with an estimated 300 to 500 patients affected at present. These disorders can best be diagnosed through analysis of family history, a compilation of clinical history, including age of primary presentation and frequency/duration of episodes, physical examination, laboratory and histological testing, and genetic analysis, although detectable genetic mutations are not common to all patients with CAPS.

Rilonacept (Arcalyst; Regeneron), which is administered as a weekly subcutaneous injection, is a targeted inhibitor of interleukin-1, the key inflammatory driver in CAPS. It was granted marketing authorization by the US FDA in February 2008 and is currently the only therapy approved for use in CAPS. Regeneron has developed Regeneron ARC (Arcalyst Resource Center) as a comprehensive support programme to provide assistance to physicians in not only diagnosing appropriately but also in referring CAPS patients to financial-assistance programmes when appropriate. ARC also encompasses a customized distribution channel through specialty pharmacies and an ongoing monitoring programme for continued patient support.

The drug has a premium price of US$250,000 annually, and analyst estimates of the market potential for rilonacept in CAPS range from $10–35 million. These estimates vary widely in part owing to uncertainty over the potential impact on patient compliance of adverse reactions observed so far with rilonacept therapy, which have ranged from mild injection-site reactions to serious infections.

Regeneron is planning a regulatory filing for rilonacept in the EU in 2008, and is also exploring the product potential in other indications, the most advanced and significant of which is gout.