With the aim of adding yet another program to its expanding antibody drug pipeline, Medarex Inc. signed Dutch firm Organon NV to a joint development and commercialization deal.

The companies will use Medarex's UltiMAb Human Antibody Development System to discover and develop a fully human monoclonal antibody against an undisclosed target chosen by Organon in the areas of cancer and autoimmune disease. While specific terms of the deal were not revealed, it is structured as "a 50-50 partnership," said Irwin Lerner, chairman and interim president and CEO of Medarex. Both firms will share development and commercialization responsibilities and also share in revenues from any product sales.

Medarex has a previous collaboration with Organon, of Oss, the Netherlands, which is being acquired by Schering-Plough Corp., of Kenilworth, N.J. for about $14.4 billion. The companies signed an alliance in February 2006 to use the UltiMAb system to generate therapeutic antibodies against disease targets discovered by Organon. The two deals involve separate disease targets, Lerner said.

The Organon collaboration is the latest in a long string of partnership and licensing deals for Medarex. Founded in 1987 to specifically focus on monoclonal antibodies, the Princeton, N.J.-based firm has gained attention from most of industry's heavy hitters, striking deals with companies such as Amgen Inc., Eli Lilly and Co. Inc., Novartis AG, Bristol-Myers Squibb Co., ImClone Systems Inc. and MedImmune Inc.

To date, the company has in its pipeline - on its own and with partners - more than 30 clinical candidates, including six in Phase III development, and is poised to "spearhead the development of immunotherapeutics," Lerner told BioWorld Today. He predicts that the field of immunotherapeutics will grow "significantly and dramatically in the next few years.

"I think we're in rather an enviable position," he said, adding that he foresees additional partnerships down the road. "The work we've done is attracting a great deal of interest from pharma."

The company's UltiMAb technology is designed to make antibodies with fully human protein sequences using transgenic strains of mice, replacing mouse antibody gene expression with human antibody gene expression. While the platform's broad application lends itself to a large number of partnership opportunities, Medarex is much more than a platform company.

"We're a products company," Lerner said, with most of its research and development efforts focused in areas of oncology and autoimmune disorders.

And despite the recent spate of acquisitions involving antibody firms - Abgenix Inc., Cambridge Antibody Technology Group plc, Abmaxis Inc. and Domantis Ltd. were bought last year - Medarex has no intention of going that route, Lerner said. "Our current strategy is to build a fully integrated company developing fully human monoclonal antibodies," he said.

The company would have an opportunity to begin building its own sales force if it exercises a co-promotion option as part of its collaboration with New York-based BMS for ipilimumab (MDX-010), which is in pivotal testing in melanoma. Pending positive results, the companies anticipate filing for regulatory approval around the end of the year. Ipilimumab is an antibody against CTLA-4, a molecule on T cells that suppresses the immune response.

Other products in Phase III development include inflammatory disease drugs CNTO 148 (golimumab) and CNTO 1275, an anti-IL-12/IL-23 antibody. Both of those are partnered with Horsham, Pa.-based Centocor Inc. Three cancer products partnered with Genmab A/S - HuMax-CD4, HuMax-CD20 and HuMax-EFGR also are in Phase III testing. Medarex, which spun out Genmab, of Copenhagen, Denmark, in 1999, retains an 11 percent equity stake in the company.

For the first three months of 2007, Medarex reported a non-GAAP net loss of $35.9 million, or 29 cents per share. As of March 31, its cash, cash equivalents and marketable securities totaled about $458.5 million.

Shares of Medarex (NASDAQ:MEDX) gained 51 cents Wednesday to close at $15.16.