Sanofi-Aventis has increased its stake in Regeneron and will collaborate with the US biotech company on new antibody research.

The companies have signed a deal to discover, develop, and commercialise fully-human therapeutic antibodies using Regeneron's proprietary VelociSuite of technologies

The French pharma company will increase its stake in Regeneron from 4% to about 19% with the purchase of 12 million new shares.

Sanofi will also make an $85 million upfront payment to Regeneron and fund up to $475 million of research over the next five years, with the option of extending the agreement for an extra three years.

The deal will give exclusive rights to co-develop each drug candidate in the collaboration portfolio.

Development costs will be shared between the two companies, with Sanofi funding them in advance and Regeneron reimbursing half from its share of future profits.

The first antibody to enter clinical trials is an antibody to the Interleukin-6 receptor (IL-6R) which is being investigated as a rheumatoid arthritis treatment. The second is expected to be an antibody to Delta-like ligand-4 (Dll4), which is due to start its clinical development in 2008.

Sanofi will take the lead in the marketing of the drugs and Regeneron will have the right to co-promote any and all collaboration products worldwide.

pharmafocus@wiley.co.uk