EU/3/19/2162: Orphan designation for the treatment of Stargardt's disease

Stargardt’s disease is a hereditary disorder of the eye that leads to progressive loss of sight. In most cases 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 vitamin A byproducts 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. As a result, deposits known as lipofuscins, made of fats, proteins and harmful vitamin A byproducts, 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 in 10,000 people in the European Union (EU). This was equivalent to a total of 52,000 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 28), Norway, Iceland and Liechtenstein. This represents a population of 518,400,000 (Eurostat 2019).

At the time of designation, no satisfactory methods were authorised in the EU for the treatment of Stargardt’s disease.

Supportive care such as vision aids and visual rehabilitation were available. Patients were recommended to wear UV-blocking sunglasses and to avoid vitamin A supplements with the aim of slowing down progression of the disease.
 

The medicine reduces the action of an enzyme known as RPE65 that helps provide vitamin A to cells in the retina; vitamin A is necessary for vision. In patients with Stargardt’s disease, vitamin A byproducts can form harmful substances that are not cleared away. These substances build up in the eyes as part of lipofuscins. By reducing RPE65's activity, the medicine is expected to reduce the build-up of these harmful substances, thus slowing down the loss of vision.

The effects of emixustat hydrochloride have been evaluated in experimental models.

At the time of submission of the application for orphan designation, clinical trials with emixustat hydrochloride in patients with Stargardt’s disease were ongoing.

At the time of submission, emixustat hydrochloride was not authorised anywhere in the EU for the treatment of Stargardt’s disease. Orphan designation of had been granted in the United States for this condition.

In accordance with Regulation (EC) No 141/2000, the COMP adopted a positive opinion on 17 April 2019, 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.