EU/3/13/1103

Chronic thromboembolic pulmonary hypertension is a condition where there is high blood pressure in the arteries that supply the lungs. The increased blood pressure in the arteries of the lungs is caused by a blockage due to blood clots, which results in progressive narrowing of such arteries and a subsequent thickening in the muscles in the walls of the arteries, making it harder for the heart to pump blood to the lungs.

Chronic thromboembolic pulmonary hypertension is chronically debilitating due to symptoms such as fatigue and dyspnoea (difficulty breathing), which limit daily activities. If untreated it may also be life-threatening due to the development of heart failure.

At the time of designation, chronic thromboembolic pulmonary hypertension affected between 0.10 and 0.52 in 10,000 people in the European Union (EU). This was equivalent to a total of between about 5,000 and 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 509,000,000 (Eurostat 2013).

At the time of designation, no medicines were authorised in the EU specifically for chronic thromboembolic pulmonary hypertension. Some patients were treated with surgery or lung transplantation.

Treprostinil sodium is a molecule that is very similar to prostacyclin, a natural substance that dilates (widens) the blood vessels and prevents blood clotting. In patients with chronic thromboembolic pulmonary hypertension, treprostinil sodium is expected to act in the same way as prostacyclin to dilate the pulmonary arteries and prevent blood clotting, lowering the blood pressure in the pulmonary artery and improving the symptoms of the disease.

The effects of treprostinil sodium have been evaluated in experimental models.

At the time of submission of the application for orphan designation, no clinical trials with treprostinil sodium initiated by the sponsor in patients with chronic thromboembolic pulmonary hypertension had been started.

Treprostinil sodium was authorised in the United States and in many EU Member States for the treatment of pulmonary arterial hypertension, which is another type of pulmonary hypertension.

At the time of submission, treprostinil sodium was not authorised anywhere in the EU for chronic thromboembolic pulmonary hypertension 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 9 January 2013 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.