LONDON - The European Patent Office has upheld without amendment Cambridge Antibody Technology Group plc's patent on the phage display of antibodies. The McCafferty patent, EP-0-589-877, was contested by MorphoSys of Germany, BioInvent of Sweden and Dyax of the U.S.

Shares in CAT, based in Melbourn, Cambridgeshire, rose on July 4 by #2.37 to #32.25 after the decision was announced.

MorphoSys, of Munich, said the decision would not impact its ability to continue to develop and apply its proprietary HuCAL (Human Combinatorial Antibody Library) technology. The company said the HuCAL-Fab library, launched in January, is not covered by this ruling. MorphoSys recently acquired a license from Genentech Inc. covering phage display screening, and claims this means it has all the licenses required to practice its HuCAL technologies.

"This decision by the EPO will have no effect on our ability to continue to commercialize our proprietary HuCAL scFv technology," commented Thomas von Rueden, chief scientific officer. "It is our view, which has been confirmed by an independent patent attorney, that the technology we use to screen our single-chain libraries does not fall within the scope of the McCafferty patent claims."

CAT said it will continue the legal action it filed against MorphoSys in September 1998. This action claims infringement of McCafferty, and another CAT patent, Winter II, which covers antibody gene expression. In October 1999, MorphoSys claimed the EPO had decided in its favor in the dispute over Winter II, after it lodged an opposition against the patent in an attempt to narrow the scope of protection.

MorphoSys wanted to have claims 1 to 31 of the Winter II patent modified and claim 32 deleted. The EPO ruled that claims 1 to 31 remain unchanged, while claim 32 was modified. CAT claims the decision was in its favor, and that MorphoSys' HuCAL library infringes the Winter II patent.