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Orphan designation

Please note that this product was withdrawn from the Community Register of designated orphan medicinal products in March 2009 on request of the sponsor.

On 16 February 2006, orphan designation (EU/3/06/357) was granted by the European Commission to Prosensa B.V., The Netherlands, for 2'-O-methyl-phosphorothioate oligonucleotide for the treatment of Duchenne muscular dystrophy.

What is Duchenne muscular dystrophy?

Duchenne muscular dystrophy is an inherited genetic disease with onset usually before the age of 6. It is characterised by symmetrical progressive diminishing and weakness of the muscles, first at the height of the pelvis and legs, later on also the muscles of the chest and arms are involved. Genes located on structures present in each cell of the body (the chromosomes), carry the genetic information that determines the characteristics of each individual. In humans, the so-called X and Y-chromosomes determine the sex, 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 single copy of chromosome X, thus one single copy of dystrophin gene, they have much higher probabilities of suffering from Duchenne muscular dystrophy. Duchenne muscular dystrophy is chronically debilitating and life-threatening.

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

At the time of designation, Duchenne muscular dystrophy affected approximately 0.5 in 10,000 people in the European Union (EU)*. This is equivalent to a total of around 23,000 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 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 25), Norway, Iceland and Liechtenstein. This represents a population of 459,700,000 (Eurostat 2004).

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 as supportive treatments.

How is this medicine expected to work?

2'-O-methyl-phosphorothioate oligonucleotide is a medicinal product, which might overcome the abnormality in the production of dystrophin. The product would allow skipping the abnormal parts of the gene responsible for the lack of functional dystrophin production. Thus it could enable the production of shorter versions of the dystrophin protein, but still capable of ensuring the same functions as the normal full-length dystrophin.

What is the stage of development of this medicine?

The evaluation of the effects of 2'-O-methyl-phosphorothioate oligonucleotide in experimental models is ongoing.
At the time of submission of the application for orphan designation, no clinical trials in patients with Duchenne muscular dystrophy were initiated.
2'-O-methyl-phosphorothioate oligonucleotide was not authorised anywhere worldwide for Duchenne muscular dystrophy or designated as orphan medicinal product elsewhere for this condition, at the time of submission.
According to Regulation (EC) No 141/2000 of 16 December 1999, the Committee for Orphan Medicinal Products (COMP) adopted on 11 January 2006 a positive opinion recommending the grant of the above-mentioned 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 Community) 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>2'-O-methyl-phosphorothioate oligonucleotide</p>
Active substance2'-O-methyl-phosphorothioate oligonucleotide
Medicine Name
Disease/conditionTreatment of Duchenne muscular dystrophy
Date of decision15/02/2006
Orphan decision numberEU/3/06/357

Review of designation

Sponsor’s contact details:

Prosensa B.V.
Einsteinweg 55
2333 CC Leiden
The Netherlands
Telephone: +31 71 527 42 02

Patients’ associations contact points:

Duchenne Parent Project UK (PPUK)
41 West Street
E11 4LJ
United Kingdom
Telephone: +44 20 85 56 99 55

AFM : Association Française contre les Myopathies
BP 59
1 Rue de l'Internationale
91002 Evry Cedex
Telephone: +33 1 69 47 28 28 / +33 81 08 11 088
Telefax: +33 1 60 77 12 16

DGM : Deutsche Gesellschaft für Muskelkranke e.V.
Im Moos 4
79112 Freiburg
Telephone: +49 76 65 94 470
Telefax: +49 76 65 94 47 20
E-mail: info@dgm.or