EU/3/14/1422

Mucopolysaccharidosis type IIIB (also known as Sanfilippo B syndrome) is one of a group of inherited diseases caused by the lack of certain enzymes in lysosomes (structures in the body's cells that break down nutrients and other substances) that are needed to break down substances called glycosaminoglycans (GAGs). In mucopolysaccharidosis type IIIB the condition is caused by the lack of an enzyme called alpha-N-acetylglucosaminidase. This enzyme is needed to break dowNNn a GAG called heparan sulphate. Because patients with mucopolysaccharidosis type IIIB cannot break this substance down, it gradually builds up in cells in the body, particularly in the brain, and damages them. This causes a wide range of symptoms, including behavioural problems, learning disabilities, difficulty moving and sleep disturbances.

Mucopolysaccharidosis type IIIB typically starts in children between three and six years of age. It is a seriously debilitating because it leads to poor development of language skills and movement, hyperactivity and slow development. The disease usually leads to death during youth.

At the time of designation, mucopolysaccharidosis type IIIB affected approximately 0.01 in 10,000 people in the European Union (EU). This was equivalent to a total of around 500 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 28), Norway, Iceland and Liechtenstein. This represents a population of 511,100,000 (Eurostat 2014).

At the time of designation, no satisfactory methods were authorised in the EU for treating MPS IIIB.

This medicine contains as its main component the enzyme alpha-N-acetylglucosaminidase, which is missing in patients with mucopolysaccharidosis type IIIB. When given to the patient, the medicine is expected to replace the missing enzyme, breaking up heparan sulphate and thereby slowing its build-up in the body. This action is expected to reduce the symptoms of the disease.

In this medicine alpha-N-acetylglucosaminidase is bound to recombinant human insulin growth factor which attaches to a receptor found in cells and which helps to direct alpha-N-acetylglucosaminidase to the lysosomes where it can act.

The medicine is produced by a method known as 'recombinant DNA technology': it is made by cells into which a gene (DNA) has been introduced, which makes them able to produce the enzyme.

At the time of submission of the application for orphan designation, the evaluation of the effects of the medicine in experimental models was ongoing.

At the time of submission of the application for orphan designation, no clinical trials with the medicine in patients with mucopolysaccharidosis type IIIB had started.

At the time of submission, the medicine was not authorised anywhere in the EU for mucopolysaccharidosis type IIIB 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 11 December 2014 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.