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Orphan designation

On 16 April 2018, orphan designation (EU/3/18/2007) was granted by the European Commission to Dr Philippe Moullier, France, for adeno-associated viral vector serotype 8 containing the human acid alpha-glucosidase gene (also known as AAV2/8-LSPhGAA) for the treatment of glycogen storage disease type II (Pompe's disease).

What is glycogen storage disease type II (Pompe's disease)?

Glycogen storage disease type II, also known as Pompe’s disease, is an inherited disorder caused by the lack of an enzyme called acid alpha glucosidase (GAA). This enzyme is contained in lysosomes (part of the body’s cells that breaks down nutrients and other materials). GAA breaks down glycogen (a complex sugar stored in the body) into glucose (a simple sugar). When this enzyme is lacking, large amounts of glycogen build up in the muscles, including the heart and diaphragm (the main breathing muscle under the lungs). The progressive build-up of glycogen causes a wide range of signs and symptoms, including heart problems, breathing difficulties and muscle weakness.

Glycogen storage disease type II is a long-term debilitating and life-threatening disease because it causes breathing and heart problems and is associated with premature death.

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

At the time of designation, glycogen storage disease type II affected approximately 0.7 in 10,000 people in the European Union (EU). This was equivalent to a total of around 36,000 people*, and is below the ceiling for orphan designation, which is 5 people in 10,000. This isbased 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 28), Norway, Iceland and Liechtenstein. This represents a population of 517,400,000 (Eurostat 2018).

What treatments are available?

At the time of designation, Myozyme (alglucosidase alfa) was authorised for the treatment of glycogen storage disease type II in the EU. Myozyme is an ‘enzyme replacement therapy’ that works by replacing the missing GAA enzyme.

The sponsor has provided sufficient information to show that the medicine might be of significant benefit for patients with glycogen storage disease type II because laboratory studies showed that, when used together with enzyme replacement therapy, the medicine improves muscle function and lowers glycogen levels better than the authorised treatment alone. This assumption will need to be confirmed at the time of marketing authorisation, in order to maintain the orphan status.

How is this medicine expected to work?

This medicine is made of a virus containing the gene for the GAA enzyme, which is lacking in patients with glycogen storage disease type II. The virus has been designed so that it can enter liver cells after injection and enable them to produce the enzyme. By replacing the missing enzyme in this way, the medicine is expected to help relieve symptoms of the disease.

The type of virus used in this medicine (‘adeno-associated virus’) does not cause disease in humans.

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 glycogen storage disease type II had been started.

At the time of submission, the medicine was not authorised anywhere in the EU for glycogen storage disease type II. Orphan designation of the medicine had been granted in the United States for Pompe disease.

In accordance with Regulation (EC) No 141/2000 of 16 December 1999, the COMP adopted a positive opinion on 15 March 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 serotype 8 containing the human acid alpha-glucosidase gene</p>
Active substanceAdeno-associated viral vector serotype 8 containing the human acid alpha-glucosidase gene
Medicine Name
Disease/conditionTreatment of glycogen storage disease type II (Pompe's disease)
Date of decision16/04/2018
Orphan decision numberEU/3/18/2007

Review of designation

Sponsor’s contact details

Dr Philippe Moullier
1 rue du Roi Albert
44000 Nantes
Tel. +33 617 13 86 62

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.