Serono S.A. and Pfizer Inc have signed an agreement to co-promote Serono's multiple sclerosis (MS) treatment Rebif (interferon beta 1-a) in the United States.

Rebif has been shown to decrease the frequency of clinical exacerbations and delay the accumulation of physical disability associated with relapsing forms of MS. Rebif is approved for use in the United States and Europe and is registered for use in more than 70 countries worldwide.

Under the terms of the agreement, Pfizer will pay Serono an up-front fee of $200 million, will share all commercialization and development costs in the U.S., and will receive a payment based on Rebif sales in the United States. Serono will record all sales and continue to distribute the product in the U.S. The dedicated sales forces of the two companies will provide Rebif with significantly greater reach than MS competitors in the U.S. The product will continue to be sold under the Rebif brand name. Serono will continue to be sole marketer for Rebif in the rest of the world.

Multiple sclerosis is a chronic, inflammatory condition of the nervous system and is the most common non-traumatic neurological disease in young adults. MS affects approximately 350,000 Americans. While symptoms can vary, the most common symptoms of MS include blurred vision, numbness or tingling in the limbs and problems with strength and coordination. The relapsing forms of the disease are the most common forms of MS.

The U.S. Food and Drug Administration approved Rebif on March 07, 2002 under the terms of the Orphan Drug Act (ODA) for the treatment of patients with relapsing forms of MS. Until this approval by the FDA, Rebif could not be marketed in the U.S. due to the Orphan Drug status of another interferon beta-1a product, Avonex, whose exclusivity under the ODA was granted in 1996 and will not expire until May 2003. Rebif was able to overcome this Orphan Drug exclusivity and gain marketing approval under the terms of the ODA by demonstrating clinical superiority over Avonex at 24 weeks in the EVIDENCE head-to-head study.