By Lisa Seachrist

Washington Editor

Angling to find a way into the U.S. market, Ares-Serono International S.A. has started a head-to-head study of its recombinant interferon beta-1a, Rebif, against Biogen Inc.'s recombinant interferon beta-1a, Avonex, in the treatment of relapsing-remitting multiple sclerosis (MS).

The study will be comparing high-dose Rebif with the recommended dose of Avonex to see if the higher-dose formulation offers any patient benefits. A positive result from this study could open an avenue for Rebif to gain access to the U.S. market, where Biogen's Avonex enjoys orphan drug protection.

"The purpose of this study is to see if there are additional benefits at a higher dosage," said Barbara Yates, director of public relations for Serono Laboratories Inc., the Norwell, Mass.-based U.S. affiliate of Geneva, Switzerland-based Ares-Serono. "If so, there is a possibility Rebif can be made available to patients in the U.S. The first step is to do the science."

The Ares-Serono trial is based on mounting clinical evidence that patients respond better to higher doses of beta interferon, the company said.

The comparative trial will test the two drugs in more than 600 MS patients with relapsing-remitting disease. The study will compare a 132 microgram dose of Rebif (44 micrograms three times per week) to a 30 microgram dose of Avonex per week. A number of U.S. and European sites already have begun enrolling patients in this study, which is designed to examine relapse and magnetic resonance images of MS lesions in the brain to establish disease progression at six months and one year.

Rebif is given as a subcutaneous injection. Avonex is an intramuscular injection. Approximately 1 million to 2 million people worldwide are living with multiple sclerosis, which is a chronic debilitating disease of the central nervous system that affects mainly young adults.

Rebif is approved in 49 countries, but is barred by provisions in the Orphan Drug Act from entering in the U.S. marketplace. However, other provisions in the law permit the FDA to approve therapies designed to treat orphan diseases if those therapies offer improved efficacy or safety over the protected therapy.

"We have been in continuing discussion with FDA about our trial design," Yates said. "And, we've addressed concerns they had with the trial. But that is the most I can say."