Biogen Inc. said Thursday it has signed a worldwide researchand licensing agreement with Mallinckrodt Medical Inc. todevelop nuclear imaging products to identify the presence ofblood clots in veins and arteries.

The agreement is the first for Biogen involving its anti-thrombotic drug hirulog. Hirulog is a "rationally designed" drug,constructed using an understanding of the three-dimensionalstructure of the hirudin protein molecule. Hirudin is found inthe saliva of the medicinal leech.

Mallinckrodt, which focuses on radiopharmaceuticals andoperates a network of nuclear medicine pharmacies, hasexclusive rights to use hirulog to produce nuclear medicineagents for visualizing blood clots. This involves labelinghirulog with a radioactive agent so that clots can be seen witha gamma camera.

St. Louis-based Mallinckrodt, a unit of Imcera Group Inc., willdevelop the imaging product and Biogen will supply themolecules. Biogen of Cambridge, Mass., will receive salesroyalties. The agreement can be expanded to include additionalmolecules and other diagnostic modalities, such as magneticresonance imaging and CT scans. No further terms weredisclosed.

Biogen is conducting Phase II clinical trials of hirulog as atherapy to prevent and treat diseases caused by blood clots.

Biogen stock (NASDAQ:BGEN) closed at $25.75, down $1, onThursday.

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