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Orphan designation

On 27 October 2011, orphan designation (EU/3/11/917) was granted by the European Commission to Institut Pasteur, France, for adeno-associated viral vector containing the human alpha-N-acetylglucosaminidase gene for the treatment of mucopolysaccharidosis type IIIB (Sanfilippo B syndrome).

What is mucopolysaccharidosis type IIIB?

Mucopolysaccharidosis type IIIB (also known as Sanfilippo B syndrome) is an inherited disease that is caused by the lack of an enzyme (a specialised type of protein) called alpha-N-acetylglucosaminidase. This enzyme is needed to break down a substance in the body called heparan sulphate. Because patients with mucopolysaccharidosis type IIIB cannot break this substance down, it gradually builds up in cells in the body, particularly in the brain, and damages them. This causes a wide range of symptoms, including behavioural problems, learning disabilities, difficulty moving and sleep disturbances. The disease typically starts in children between three and six years of age.

Mucopolysaccharidosis type IIIB is a seriously debilitating and life-threatening disease because it leads to poor development of language skills and movement, hyperactivity and slow development. The disease usually leads to death during adolescence.

What is the estimated number of patients affected by the condition?

At the time of designation, mucopolysaccharidosis type IIIB affected approximately 0.005 in 10,000 people in the European Union (EU)*. This is equivalent to a total of around 250 people, and is below the ceiling 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 (EU 27), Norway, Iceland and Liechtenstein. This represents a population of 506,300,000 (Eurostat 2011).

What treatments are available?

At the time of designation, no satisfactory methods were authorised in the EU for treating mucopolysaccharidosis type IIIB.

How is this medicine expected to work?

Adeno-associated viral vector containing the human alpha-N-acetylglucosaminidase gene is a medicine that works by delivering genes into the body. It is made up of a virus that contains the gene for producing the missing enzyme, alpha-N-acetylglucosaminidase. The type of virus used in this medicine (adeno-associated virus) does not cause disease in humans.

When injected into the brain, the virus is expected to carry the gene mainly into the brain cells. These cells are then expected to produce the missing enzyme so that it can break down the accumulated heparan sulphate and help to relieve the symptoms of the disease.

What is the stage of development of this medicine?

The effects of the medicine have been evaluated in experimental models.

At the time of submission of the application for orphan designation, no clinical trials with the medicine in patients with mucopolysaccharidosis type IIIB had been started.

At the time of submission, the medicine was not authorised anywhere in the EU for mucopolysaccharidosis type IIIB or designated as an orphan medicinal product elsewhere for this condition.

In accordance with Regulation (EC) No 141/2000 of 16 December 1999, the COMP adopted a positive opinion on 8 September 2011 recommending the granting of this designation.

Opinions on orphan medicinal product designations are based on the following three criteria:
  • 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 EU) 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.

Key facts

Product details for <p>Adeno-associated viral vector containing the human alpha-N-acetylglucosaminidase gene</p>
Active substanceAdeno-associated viral vector containing the human alpha-N-acetylglucosaminidase gene
Medicine Name
Disease/conditionTreatment of mucopolysaccharidosis type IIIB (Sanfilippo B syndrome)
Date of decision27/10/2011
Orphan decision numberEU/3/11/917

Review of designation

The Committee for Orphan Medicinal Products reviews the orphan designation of a product if it is approved for marketing authorisation.

Sponsor’s contact details

Institut Pasteur
25-28 rue du Docteur Roux
75724 Paris Cedex 15
Tel. +33 1 44 38 91 01
Fax +33 1 40 61 39 77

Patients' organisations

For contact details of patients’ organisations whose activities are targeted at rare diseases, see:

  • Orphanet, a database containing information on rare diseases which includes a directory of patients’ organisations registered in Europe.
  • European Organisation for Rare Diseases (EURORDIS), a non-governmental alliance of patient organisations and individuals active in the field of rare diseases.