Serono SA will work with IVAX Corp. to develop IVAX Corp.'s cladribine as an oral treatment for multiple sclerosis.

Cladribine is a purine analogue designed to disrupt the proliferation of certain white blood cells that are involved in the pathological process of MS. Magnetic resonance imaging data and data from Phase II trials of the drug have suggested intravenous cladribine might be effective in MS patients, the companies said, and they plan to find an optimal oral formulation and begin clinical trials.

IVAX is scheduled to receive milestone payments and would get royalties on sales of any approved product. Further financial details were not disclosed.

In a prepared statement, Serono CEO Ernesto Bertarelli said the agreement is "part of our long-term strategy for developing novel therapies in neurology. With cladribine, we plan to offer patients an oral therapy which complements Rebif." Rebif is Serono's treatment for MS.

Serono, of Geneva, markets Rebif in the U.S. and Europe. The drug competes against Avonex, developed by Biogen Inc., of Thousand Oaks, Calif. In July, Serono signed a deal with Pfizer for the pharmaceutical company to co-promote Rebif in the U.S. Serono received a $200 million up-front fee. (See BioWorld Today, July 12, 2002.)

IVAX, of Miami, has operations in 30 countries and sells its products in 70. It focuses on branded and generic equivalent pharmaceuticals and veterinary products.