EU/3/08/598

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Orphan designation

On 27 February 2009, orphan designation (EU/3/08/598) was granted by the European Commission to Prosensa Therapeutics B.V., The Netherlands, for exon 44 specific phosphorothioate oligonucleotide for the treatment of Duchenne muscular dystrophy.

For a list of the administrative updates to this public summary of opinion please refer to the PDF document below.

What is Duchenne muscular dystrophy?

Duchenne muscular dystrophy is an inherited genetic disease, which usually starts before the age of 6. It is characterised by progressive weakness of the muscles, first involving the hips and legs, and later also the muscles of the chest and arms. Genes located on structures present in each cell of the body (the chromosomes) carry the information that characterises each individual. In humans, the so-called X and Y-chromosomes determine the sex (males have one X and one Y, females have 2 Xs), but carry also other genetic information. Duchenne muscular dystrophy is caused by an abnormality of a gene located on the X chromosome. This gene is responsible for the production of a protein, dystrophin, in the muscle cells. This means that patients suffering from this condition do not produce the dystrophin protein, or produce a non-functional dystrophin. As boys, contrary to girls, only have one X chromosome, and thus one single copy of dystrophin gene, they have a much higher probability of suffering from Duchenne muscular dystrophy. Duchenne muscular dystrophy is chronically debilitating and life-threatening.

What is the estimated number of patients affected by Duchenne muscular dystrophy?

At the time of designation, Duchenne muscular dystrophy affected approximately 0.3 in 10,000 people in the European Union (EU). This was equivalent to a total of around 15,000 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. At the time of designation, this represented a population of 504,800,000 (Eurostat 2009).

What treatments are available?

At the time of submission of the application for orphan designation, no satisfactory method had been authorised in the European Union for treatment of the condition. Treatment of patients with Duchenne muscular dystrophy primarily involves physiotherapy and other supportive treatments.

How is this medicine expected to work?

Duchenne muscular dystrophy is caused by abnormalities on patients’ genetic material. This medicinal product is expected to induce dystrophin protein expression by exon skipping technology. This technology is designed to skip the areas of the genetic material that carry the errors and correct them back to the normal genetic information.

What is the stage of development of this medicine?

The effects of exon 44 specific phosphorothioate oligonucleotide have been evaluated in experimental models.

At the time of submission of the application for orphan designation, clinical trials in patients with Duchenne muscular dystrophy were ongoing.

At the time of submission, exon 44 specific phosphorothioate oligonucleotide was not authorised anywhere in the world for the treatment of Duchenne muscular dystrophy or designated as 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 5 November 2008 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;
  • and either the rarity of the condition (affecting not more than five in 10,000 people in the Community) or the 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 the quality, safety and efficacy is necessary before a product can be granted a marketing authorisation.

Key facts

Product details for <p>Exon 44 specific phosphorothioate oligonucleotide</p>
Active substanceExon 44 specific phosphorothioate oligonucleotide
Medicine Name
Disease/conditionTreatment of Duchenne muscular dystrophy
Date of decision26/02/2009
OutcomePositive
Orphan decision numberEU/3/08/598

Review of designation

Sponsor’s contact details

Prosensa Therapeutics B.V.
J.H. Oortweg 21
2333 CH Leiden
The Netherlands
Tel. +31 71 33 22 691
Fax +31 71 33 22 088
E-mail: info@prosensa.nl

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.