The U.S. Patent and Trademark Office has entered a summaryjudgment against Creative BioMolecules Inc. in its interferenceaction against Genex Corp.'s patent on single-chain antigen-binding proteins (SCAs).

Creative asked the PTO to declare an interference last Augustafter Genex was granted its patent No. 4,946,778. Creative,which filed its own patent application in 1987, calls itsmolecules biosynthetic antibody binding sites (BABS).

The molecules are being developed to deliver anti-cancer drugsdirectly to tumors and for imaging techniques.

The PTO's decision "is clearly a disappointment," CharlesCohen, president of Creative, said Wednesday. "But there isprobably enough appreciation of the proceedings in the patentworld to know this is never the end of the story.

"We are pursuing the options that are available to us," Cohensaid. "The very best option is trying to effectively prosecutepatents that are outside the scope of claims allowed Genex. Wehave a number of independent claims from that first patent(filing) that we hope will issue."

Creative, a privately held company based in Hopkinton, Mass.,also will probably exercise its right to appeal before the Courtof Appeals for the Federal Circuit in Washington, D.C., Cohensaid. He said Creative has 60 days to decide if it will do so.

Both SCAs and BABS consist of a single short polypeptide chaincontaining binding sites usually found in the four polypeptidechains of a monoclonal antibody (MAb). The molecules "seem toduplicate the affinity and specificity of the parent monoclonaland are produced readily in E. coli (bacteria)," said Cohen.

In addition, according to Genex, the simpler protein structureof the molecules should make them easier to manufacture on acommercial scale than MAbs and shouldn't cause the allergicresponses often caused by the mouse portion of conventionalMAbs.

Genex estimates a potential world market of $100 million forthe molecules, which are in the early stages of development.Genex is preparing samples to begin preclinical trials directedat cancer therapeutics, and Creative is conducting animaltrials of in vivo imaging of cardiac muscle damage after heartattacks.

Last month, Enzon Inc. (NASDAQ:ENZN) of South Plainfield, N.J.,agreed to acquire financially strapped Genex (NASDAQ:GNEX) ofGaithersburg, Md., in a stock deal worth about $13 million. Thepending acquisition hasn't changed Genex's plans to developSCAs, said Genex spokeswoman Diana Hopkins.

-- Karen Bernstein BioWorld Staff

(c) 1997 American Health Consultants. All rights reserved.