EU/3/16/1710

On 14 July 2016, orphan designation (EU/3/16/1710) was granted by the European Commission to Vall d'Hebron Institute of Research, Spain, for triheptanoin for the treatment of McArdle’s disease.

What is McArdle’s disease?

McArdle’s disease (also known as glycogen storage disease type V) is an inherited disorder caused by the lack of an enzyme called myophosphorylase. This enzyme breaks down glycogen (a complex sugar) stored in the muscles into glucose (a simple sugar), which is used to generate energy. When this enzyme is lacking, less energy is made in the muscles, leading to decreased ability to exercise, muscle fatigue (loss of strength in muscles), contractures (permanent shortening and hardening of muscles), and sometimes myoglobinuria (presence of a protein from broken-down muscle in the urine, which can damage the kidneys).

McArdle’s disease is a long-term debilitating disease because it reduces the ability to exercise, causes tiredness and stiffness, and shortens and hardens muscles. It is also life-threatening because it can cause sudden breakdown of muscle, which can cause kidney damage and lead to death.

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

At the time of designation, McArdle’s disease 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 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).

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* 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 513,700,000 (Eurostat 2016).

What treatments are available?

At the time of submission of the application for orphan designation, no satisfactory method had been authorised in the European Union for the treatment of McArdle’s disease.

How is this medicine expected to work?

How is this medicine expected to work?

Triheptanoin is an oil which is broken down in the liver into substances that can be used to generate energy without the need for myophosphorylase, the enzyme lacking in patients with McArdle’s disease. By bypassing the need for myophosphorylase, this medicine is expected to increase energy generation in muscle and improve the symptoms of the disease.

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, clinical trials with triheptanoin in patients with McArdle’s disease were ongoing.

At the time of submission, triheptanoin was not authorised anywhere in the EU for McArdle’s disease 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 16 June 2016 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.

The Committee for Orphan Medicinal Products reviews the orphan designation of a product if it is approved for marketing authorisation.