By Lisa Seachrist

MedImmune Inc. entered into a collaboration to employ privately held Ixsys Inc.¿s Directed Evolution technology to develop four monoclonal antibodies.

The deal could be worth in excess of $50 million for San Diego-based Ixsys. Under the terms of the collaboration, Ixsys will optimize antibodies for Gaithersburg, Md.-based MedImmune, which will direct the molecules through clinical development.

¿What MedImmune does better than anybody is take antibodies and run them through the FDA,¿ said William Huse, CEO and chief scientific officer for Ixsys. ¿This is a very nice partnership in that respect.¿

MedImmune will make a $6.4 million equity investment in Ixsys. In addition, MedImmune will fund research on the antibodies as well as make milestone payments totaling up to $50 million. Ixsys also will receive royalties on any products that make it to the market.

The collaboration¿s lead product will be Vitaxin ¿ a humanized monoclonal antibody developed by Ixsys. Vitaxin inhibits a key pathway in the formation of new blood vessels by binding to the integrin called alpha-v beta-3 specifically found on newly sprouting blood vessels. The antibody inhibits the growth of new blood vessels, or angiogenesis.

Solid tumors require additional blood supplies in order to keep growing and send out signals to encourage angiogenesis. Blocking the growth of those blood vessels can stymie the tumors.

¿We believe Vitaxin has behind it some of the best science in the angiogenesis inhibitor field,¿ said Mark Kaufmann, director of planning and analysis for MedImmune. ¿We will be looking at the second-generation Vitaxin compounds before deciding how to move forward.¿

Ixsys has just completed enrollment for a Phase II study of Vitaxin in patients suffering from leiomyosarcoma, a cancer of smooth muscle for which there is no current therapy. Huse said the company was testing Vitaxin in that particular cancer because its clinical experts had identified those tumors as likely to be particularly susceptible to angiogenesis inhibitors.

In addition to Vitaxin, MedImmune will have Ixsys optimize some of the antibodies that are currently in-house at MedImmune. Those antibodies have yet to be identified.

¿The ability to optimize antibodies with the Directed Evolution technology makes this collaboration a good strategic fit for us,¿ Kaufmann said. ¿For Ixsys, we have a hospital-based sales force that will be able to branch out into oncology.¿

MedImmune¿s stock (NASDAQ:MEDI) closed Thursday at $55.125 a share, down $3.125. n