NeoRx Corp. announced on Thursday that it has signed a secondcollaboration with Genentech Inc. to test an antibody-guidedradiotherapy for cancer.

The first collaboration tested a mouse antibody directed to theHER2 oncoprotein expressed by breast and ovarian cancers.HER2 causes a virulent form of cancer that responds poorly totraditional therapies. The antibody binds to the protein,preventing it from causing the unchecked growth of tumorcells.

Genentech (NYSE:GNE) tested the mouse antibody with aniodine radiolabel in Phase I trials. "Presumably they got goodenough results to be interested in pursuing our collaboration,"said Robert Schroff, NeoRx's director for the project.

The new collaboration, a preclinical program, will test theSeattle company's rhenium labeling technologies withGenentech's humanized version of the antibody. Humanizedantibodies take the targeting end of the mouse immunoproteinand splice it to a human antibody. The aim is to make thechimeric molecule less likely to provoke an immune reaction.

The collaborators each will do some of the preclinical work andwill pay their own costs, "which in our case are small," saidRobert Littauer, NeoRx vice president and chief financialofficer.

NeoRx shares (NASDAQ:NERX) gained 50 cents to $4.75. -- RF

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