EU/3/01/078: Orphan designation for the treatment of mucopolysaccharidosis type II (Hunter's syndrome)

Mucopolysaccharidosis is a so called lysosomal storage disease. It is caused by the absence of the enzyme iduronate-2-sulfatase, which is found in lysosomes. Lysosomes are small organelles that contain several enzymes important to break down substances like proteins and sugars. Normally, iduronate-2-sulfatase would break down two specific mucopolysaccharides. As it is absent in patients with Hunter Syndrome, these mucopolysaccharides build up in the lysosomes. The condition is chronically debilitating and life-threatening in particular due to neurologic decline, difficulties to breath and heart failure.

At the time of designation, mucopolysaccharidosis, type II (Hunter Syndrome) affected approximately 0.02 in 10,000 people in the European Union (EU)*. This is equivalent to a total of around 760 people, and is below the threshold for orphan designation, which is 5 people in 10,000. This is based on the information provided by the sponsor and the knowledge of the Committee for Orphan Medicinal Products (COMP).

*Disclaimer: For the purpose of the designation, the number of patients affected by the condition is estimated and assessed on the basis of data from the European Union. At the time of designation, this represented a population of 378,800,000 (Eurostat 2001).

No medicinal products were authorised for the treatment of mucopolysaccharidosis type II (Hunter Syndrome) in the Community at the time of submission of the application for orphan drug designation.

The treatment options for mucopolysaccharidosis type II (Hunter Syndrome) patients were limited to symptomatic care.

Iduronate -2- sulfatase is the deficient enzyme in patients with mucopolysaccharidosis type II (Hunter Syndrome). By replacing it with a functioning enzyme, it is expected that the normal lysosomal function is restored and ultimately improve the overall health of the patients.

The effects of iduronate -2- sulfatase were evaluated in experimental models. At the time of submission of the application for orphan designation, one clinical trial in patients with mucopolysaccharidosis type II (Hunter Syndrome) was ongoing.

Iduronate-2-sulfatase was not marketed anywhere worldwide for the treatment of mucopolysaccharidosis, type II (Hunter Syndrome) or designated as orphan medicinal product elsewhere for this condition, at the time of submission.

In accordance with Regulation (EC) No 141/2000 of 16 December 1999, the COMP adopted a positive opinion on 26 October 2001 recommending the granting of this designation.

Update: iduronate-2-sulfatase (Elaprase) was authorised in the EU on 8 January 2007 for the long-term treatment of patients with Hunter syndrome (Mucopolysaccharidosis II, MPS II).

Heterozygous females were not studied in the clinical trials.

• the seriousness of the condition;
• the existence of alternative methods of diagnosis, prevention or treatment;
• either the rarity of the condition (affecting not more than 5 in 10,000 people in the European Union) or insufficient returns on investment.

Designated orphan medicinal products are products that are still under investigation and are considered for orphan designation on the basis of potential activity. An orphan designation is not a marketing authorisation. As a consequence, demonstration of quality, safety and efficacy is necessary before a product can be granted a marketing authorisation.