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Orphan designation

On 18 March 2009, orphan designation (EU/3/09/621) was granted by the European Commission to Isabelle Ramírez, Germany, for 2,2-dimethylbutyric acid, sodium salt for the treatment of sickle cell disease.

What is sickle cell disease?

Sickle cell disease is a genetic disease in which the red blood cells become rigid and sticky, and change from being disc-shaped to being crescent-shaped (like a sickle). The change in shape is caused by the presence of an abnormal form of haemoglobin, the protein in red blood cells that carries oxygen around the body. In patients with sickle cell disease, the abnormal red blood cells attach to walls of blood vessels and block them, restricting the flow of nutrients and oxygen to the internal organs, such as the heart, the lungs, and the spleen. This causes severe pain and damage to these organs. Because the abnormal red blood cells have a shorter life span, the disease also causes anaemia (low red blood cell counts).

Sickle cell disease is a severe disease that is long lasting and may be life threatening because of its effects on the heart and the lungs.

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

At the time of designation, sickle cell disease affected less than 1 in 10,000 people in the European Union (EU)*. This is equivalent to a total of fewer than 50,000 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).


What treatments are available?

At the time of designation, there was one medicine authorised for sickle cell disease in the EU. The main treatment for sickle cell disease was blood transfusion. This was usually combined with iron chelators, medicines used to reduce the high iron levels in the body caused by repeated blood transfusions. In some cases, bone marrow transplant was used (a complex procedure where the bone marrow of the patient is destroyed and replaced with bone marrow from a matched donor) to allow the patient to produce red blood cells containing normal haemoglobin.

The sponsor has provided sufficient information to show that 2,2-dimethylbutyric acid, sodium salt might be of significant benefit for the patients because of the way the medicine is expected to work. 2,2-Dimethylbutyric acid, sodium salt could be an alternative treatment for sickle cell disease, or may be used in combination with existing treatments. This assumption will need to be confirmed at the time of marketing authorisation, in order to maintain the orphan status.

How is this medicine expected to work?

2,2-Dimethylbutyric acid, sodium salt is expected to increase the amount of haemoglobin in the blood by stimulating the production of foetal haemoglobin. Foetal haemoglobin is the main type of haemoglobin found in unborn children. The levels of foetal haemoglobin usually decrease to around 1% of the total haemoglobin by the end of the second year of life. In sickle cell disease, foetal haemoglobin is expected to replace the abnormal haemoglobin in red blood cells following treatment with 2,2-dimethylbutyric acid, sodium salt. This will stop the red blood cells changing their shape, reducing the risk of blood vessels becoming blocked.

What is the stage of development of this medicine?

The effects of 2,2-dimethylbutyric acid, sodium salt have been evaluated in experimental models.

At the time of submission of the application for orphan designation, clinical trials in healthy volunteers were ongoing.

At the time of submission, 2,2-dimethylbutyric acid, sodium salt was not authorised anywhere in the EU for sickle cell disease. Orphan designation of the medicine had been granted in the United States of America for this condition.

In accordance with Regulation (EC) No 141/2000 of 16 December 1999, the COMP adopted a positive opinion on 9 February 2009 recommending the granting of this designation.

  • the seriousness of the condition;


Key facts

Product details for <p>2,2-Dimethylbutyric acid, sodium salt</p>
Active substance2,2-Dimethylbutyric acid, sodium salt
Medicine Name
Disease/conditionTreatment of sickle cell disease
Date of decision17/03/2009
Orphan decision numberEU/3/09/621

Review of designation

Sponsor’s contact details:

Isabelle Ramirez
Friedrichstrasse 5

Patients’ associations contact points:

Sickle Cell Society
54 Station Road
London NW10 4UA
United Kingdom
Telephone: +44 20 8961 7795
Telefax: +44 20 8961 8346

Fédération des Malades Drépanocytaires et Thalassémiques
Laboratoire de Biochimie
CHU Hôpital Henri Mondor
51 Avenue du Marchal de Lattre de Tassigny
94010 Creteil Cedex
Telephone: +33 1 64 30 93 32
Telefax: +33 1 64 30 93 32

ENERCA European Network for Rare and Congenital Anaemias
Red Cell Pathology Unit
Hospital Clnici Provincial
Villarroel 170
08036 Barcelona
Telephone: +34 93 451 59 50
Telefax: +34 93 227 54 51