EU/3/12/1077

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Orphan designation

On 6 December 2012, orphan designation (EU/3/12/1077) was granted by the European Commission to Prosensa Therapeutics B.V., the Netherlands, for exon-52-specific phosphorothioate oligonucleotide for the treatment of Duchenne muscular dystrophy.

What is Duchenne muscular dystrophy?

Duchenne muscular dystrophy (DMD) is a genetic disease that gradually causes weakness and atrophy (wasting) of the muscles. It mainly affects boys, and usually starts before the age of six years. The muscle weakness usually starts in the hips and legs, before reaching the chest, arms, and sometimes the heart. Patients with DMD lack normal dystrophin, a protein found in muscles. Because this protein helps to strengthen and protect muscles from injury as they contract and relax, in patients with DMD the muscles become weak and eventually stop working.

DMD causes long-term disability and is life threatening because of its effects on the heart and the respiratory muscles (muscles that are used to breathe). The disease usually leads to death in adolescence or early adulthood.

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

At the time of designation, DMD affected approximately 0.52 in 10,000 people in the European Union (EU)*. This is equivalent to a total of around 26,000 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. This represents a population of 506,300,000 (Eurostat 2011).

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 to treat DMD. Treatment of patients with DMD primarily involves physiotherapy and other supportive treatments.

How is this medicine expected to work?

DMD is caused by defects in the gene responsible for the production of dystrophin. Often important parts of this gene called ‘exons’ are missing or damaged, which results in a very short dystrophin protein that cannot work properly. 

This medicine is an ‘antisense oligonucleotide’ medicine. It is expected to attach to a normal exon of the dystrophin gene, called exon 52, and to produce adequate levels of an ‘intermediate-length’ dystrophin protein, which works better than the very short dystrophin found in DMD. It is expected to do so by a mechanism called ‘exon skipping’, which allows skipping the areas of the gene that block the production of a dystrophin protein which is long enough to function.

What is the stage of development of this medicine?

The effects of exon-52-specific phosphorothioate oligonucleotide 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 DMD had been started.

At the time of submission, the medicine was not authorised anywhere in the EU for DMD 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 7 November 2012 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>Exon-52-specific phosphorothioate oligonucleotide</p>
Active substanceExon-52-specific phosphorothioate oligonucleotide
Medicine Name
Disease/conditionTreatment of Duchenne muscular dystrophy
Date of decision06/12/2012
OutcomePositive
Orphan decision numberEU/3/12/1077

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:

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: j.renz@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.