EU/3/05/283

Thrombocytopenic purpura (TP) is a disease where the individual's defence system (the so-called immune system) starts to react against certain of his/her own blood cells that are involved in the blood clotting process, the so-called platelets. The TP is called “idiopathic” since the reason why the body starts reacting against its own cells is unknown. As a result, there will be less platelets present in the blood (thrombocytopenia), resulting in bruising and spontaneous bleedings (this phenomenon is called purpura). ITP can be acute or chronic and can occur in both children and adults. The severity of the bruising is determined by the degree of thrombocytopenia e.g. from tiny skin dots called petechiae that occur after small injuries to spontaneous blood losses (haemorrhages) from the nose, guts, or brain vessels that can be life threatening.

At the time of designation, idiopathic thrombocytopenic purpura affected approximately 1 in 10,000 people in the European Union (EU)*. This is equivalent to a total of around 46,000 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).

Treatment of ITP depends on the form of the disease (acute or chronic) and on the age of onset. Current treatment methods include surgery consisting in spleen removal (splenectomy) or medicines. Splenectomy is performed in order to limit the destruction of the platelets. Several types of medicines were authorised in the Community for the treatment of ITP at the time of submission of the application for orphan drug designation.

Recombinant megakaryopoiesis-stimulating protein could be of potential significant benefit for the treatment of idiopathic thrombocytopenic purpura because it may act in a different way than other available medicines. This assumption will have to be confirmed at the time of marketing authorisation. This will be necessary to maintain the orphan status.

Platelets are cells that derive from a parent cell in the bone marrow, the so-called progenitor cells which will then develop into platelets by series of cell devisions. This process is called the megakaryopoiesis. Recombinant megakaryopoiesis-stimulating protein is a medicine that might increase the number of platelets by stimulating their production from the progenitor cells.

The effects of recombinant megakaryopoiesis-stimulating protein were evaluated in experimental models.

At the time of submission of the application for orphan designation, clinical trials in patients with idiopathic thrombocytopenic purpura were ongoing.

Recombinant megakaryopoiesis-stimulating protein was not marketed anywhere worldwide for treatment of idiopathic thrombocytopenic purpura, at the time of submission. Orphan designation of recombinant megakaryopoiesis-stimulating protein was granted in the United States for the treatment of idiopathic thrombocytopenic purpura.

According to Regulation (EC) No 141/2000 of 16 December 1999, the Committee for Orphan Medicinal Products (COMP) adopted a positive opinion on 7 April 2005 recommending the granting of the above-mentioned designation.

Update: Recombinant megakariopoiesis stimulating protein (Nplate) has been authorised in the EU since 4 February 2009 for adult chronic immune (idiopathic) thrombocytopenic purpura (ITP) splenectomised patients who are refractory to other treatments (e.g. corticosteroids, immunoglobulins). Nplate may be considered as second line treatment for adult non-splenectomised patients where surgery is contra-indicated.

• the seriousness of the condition,
• the existence or not of alternative methods of diagnosis, prevention or treatment and
• either the rarity of the condition (considered to affect not more than five in ten thousand persons in the Community) or the insufficient return of development investments.

Designated orphan medicinal products are still investigational products which were considered for designation on the basis of potential activity. An orphan designation is not a marketing authorisation. As a consequence, demonstration of the quality, safety and efficacy will be necessary before this product can be granted a marketing authorisation.