BRUSSELS, Belgium - The European Union (EU) has explained why it granted a marketing authorization in May to Ares Serono Group's multiple sclerosis drug despite incomplete clinical data.

The product, Rebif (interferon beta-1a), was approved under “exceptional circumstances“ upon recommendation of the EU's Committee for Proprietary Medicinal Products (CPMP) - the senior drug science committee established within the European Medicines Evaluation Agency, in London.

The CPMP found “Rebif decreases the frequency and severity of relapses over two years,“ and it “judged from the scientific information available that there is adequate evidence for the efficacy and clinical safety of Rebif in the approved indication“ - treatment of ambulatory patients with relapsing-remitting multiple sclerosis characterized by at least two recurrent attacks of neurological dysfunction over the preceding two-year period.

The “exceptional“ recommendation was made “because of the current lack of information on the precise mechanism of action, not yet known, by which interferon beta-1a influences the relapses, and [lack of] conclusive data on the long-term effects of Rebif on the progression of the disease and on disability pattern, which is not yet available.“

As a condition of the authorization, the company is to submit additional information on the clinical experience on an ongoing basis, and “all new studies to be carried out will be carefully monitored and the results will be reviewed annually by the CPMP.“

Such “exceptional“ authorizations are rare in Europe; this is one of what is understood to be only a handful of such concessions in the EU registration process for biotechnology-based medicines.

Altogether 54 European marketing authorization applications for biotechnology and other high-technology medicines have been submitted through the new centralized registration procedure since it was set up in 1995. The CPMP so far has given opinions on 27 of these applications, and four have been withdrawn. Over the same period, it has made decisions on more than 100 variations or extensions to marketing authorizations for such products.

The CPMP revealed its reasoning following a May 26-27 meeting in London. *