Shire of the UK won approval yesterday for Elaprase, a treatment for the rare genetic condition known as Hunter syndrome, and said it would launch the product onto the market within a month.

Elaprase (idursulfase) is the first drug to be approved for Hunter syndrome in the USA, and should transform the lives of the 500 or so sufferers of the disease, who are predominantly young males.

Hunter syndrome is also known as mucopolysaccharidosis type II and is an enzyme efficiency disorder that causes mucopolysaccharide to build up and deposit in the tissues. It is characterised by growth problems, facial deformity and abnormal organ function and can also cause mental retardation, and in severe cases patients do not tend to live beyond age 20.

Elaprase is an enzyme replacement, and like other drugs of this type for extremely rare genetic conditions is expected to reach the market with a hefty price tag. The pioneering company in this market is Genzyme, whose main products, such as Cerezyme (algucerase) for Gaucher disease and Fabrazyme for Fabry disease, typically cost $200,000 to $275,000 per patient per year, and Elaprase is expected to fall in a similar pricing bracket.

Elaprase is one of five new products at Shire that together should bring in sales of $1 billion or more by 2008, accounting for more than 40% of the company’s sales and removing its current reliance on attention deficit hyperactivity drug Adderall XR (mixed amphetamine salts), according to analysts at WR Hambrecht & Co.

The others include ADHD drugs Daytrana (methylphenidate) and NRP104 (lisdexamfetamine dimesylate), Mesavance (mesalamine) for inflammatory bowel disease and red cell booster Dynepo (epoetin delta).

Shire filed for approval of Elaprase in the European Union last December, and expects to win approval by the end of the year. Worldwide there are around 2,000 individuals with Hunter syndrome in countries where reimbursement may be possible, according to the company.

Elaprase was approved after a randomized, double-blind, placebo-controlled study of 96 patients with Hunter syndrome showed that the treated participants had an improved capacity to walk. At the end of the 53–week trial, patients who received Elaprase infusions experienced on average a 38-yard greater increase in the distance walked in six minutes compared to the patients on placebo.