EU/3/08/609: Orphan designation for the treatment of Stargardt's disease

Stargardt's disease is a genetic (hereditary) disorder of the eye that leads to progressive loss of sight. Stargardt's disease is caused by abnormalities in a gene called ABCA4. The ABCA4 gene is responsible for the production of a protein called ABCR that regulates the transport of substances in and out of some cells in the retina (the light-sensitive surface at the back of the eye). In patients with Stargardt's disease, ABCR does not work properly. This causes deposits to build up inside the retina cells, which become damaged and eventually die.

Stargardt's disease is a long-term debilitating disease because the patient's sight becomes progressively worse and eventually leads to blindness.

At the time of designation, Stargardt's disease affected approximately 1.1 in 10,000 people in the European Union (EU). This was equivalent to a total of around 56,000 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).

At the time of submission of the application for orphan designation, no satisfactory methods were authorised in the EU for the treatment of the condition. Patients with Stargardt's disease were mainly given genetic counselling (discussion of the risk of passing the condition on to children), and general support such as information and regular medical follow-up.

Adeno-associated viral vector serotype 5 containing the human ABCA4 gene is made up of a virus that contains the human ABCA4 gene. The virus is used to carry the ABCA4 gene into the cells of the retina. By doing this, these cells are expected to start producing the ABCR protein, which will replace the defective protein. When it is injected into the eye, this may relieve the symptoms of the disease and prevent the loss of sight. The type of virus used in this medicine (an adeno-associated virus) is modified so that it does not cause disease in humans.

The effects of adeno-associated viral vector serotype 5 containing the human ABCA4 gene have been evaluated in experimental models.

At the time of submission of the application for orphan designation, no clinical trials in patients with Stargardt's disease had been started.

At the time of submission, adeno-associated viral vector serotype 5 containing the human ABCA4 gene was not authorised anywhere in the world for Stargardt's disease 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 10 December 2008 recommending the granting of this designation.

• 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 marketing authorisation.