EU/3/10/727: Orphan designation for the treatment of retinitis pigmentosa in Usher syndrome 1B

Retinitis pigmentosa is group of hereditary diseases of the eye that lead to progressive loss of sight. In patients with retinitis pigmentosa, cells in the retina (the light-sensitive surface at the back of the eye) become damaged and eventually die. Retinitis pigmentosa is seen in a variety of diseases, including a genetic condition known as Usher syndrome. This condition also causes other problems, including deafness.

Retinitis pigmentosa in Usher's syndrome is a long-term debilitating disease because it causes the patient's sight to get worse, eventually leading to blindness.

At the time of designation, retinitis pigmentosa in Usher syndrome 1B affected approximately 0.1 in 10,000 people in the European Union (EU). This was equivalent to a total of around 5,000 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 27), Norway, Iceland and Liechtenstein. At the time of designation, this represented a population of 506,300,000 (Eurostat 2010).

At the time of submission of the application for orphan designation, no satisfactory methods were authorised in the EU for treating retinitis pigmentosa in Usher syndrome 1B. Patients with the condition were given sunglasses to slow down the damage to the retina, genetic counselling (discussion of the risks of passing the condition on to children) and general support.

Retinitis pigmentosa in Usher syndrome 1B is caused by abnormalities in a gene called MYO7A. This gene is involved in the normal development of the retina. Lentiviral vector containing the human MYO7A gene is an advanced therapy medicine that belongs to the group called 'gene therapy products'. These are medicines that work by delivering genes into the body. The medicine is made up of a virus that contains normal copies of the human MYO7A gene. When the medicine is injected into the eye, the virus is expected to carry the normal MYO7A gene into the cells of the retina, which will replace the abnormal gene in Usher syndrome 1B. This is expected to reduce or reverse the damage to retina cells, slowing down or preventing the loss of vision.

The type of virus used in this medicine (lentivirus) is modified so that it does not cause disease in humans.

At the time of submission of the application for orphan designation, the evaluation of the effects of lentiviral vector containing the human MYO7A gene in experimental models was ongoing.

At the time of submission, no clinical trials with this medicine had been started in patients with retinitis pigmentosa in Usher syndrome 1B.

At the time of submission, lentiviral vector containing the human MYO7A gene was not authorised anywhere in the EU for retinitis pigmentosa in Usher syndrome 1B 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 6 January 2010 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 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.