SAN FRANCISCO -- Cetus Corp.'s hold on two key patents forpolymerase chain reaction (PCR) rests only on a rediscovery of20-year-old technology, Du Pont claimed Tuesday in anopening statement to a jury here. Du Pont seeks to have Cetus'patents ruled invalid.

Cetus responded that PCR is a novel proprietary technologythat was never used prior to its conception in 1983 by Dr. KaryMullis of Cetus. The trial before U.S. District Court JudgeMarilyn Hall Patel was initiated by Du Pont's 1989 suit againstCetus.

The stakes in the Du Pont vs. Cetus battle are high. PCRtechnology allows researchers to generate in a few hoursbillions of copies of any DNA sequence. Including diagnosticapplications, PCR could represent a $1 billion market by thelate 1990s, analysts estimate.

Patel instructed the jury that Du Pont must present "clear andconvincing evidence" that Cetus' patents are invalid. She addedthat the law presumes that the U.S. Patent and TrademarkOffice acted correctly in issuing the patents in 1987 andaffirming their validity in re-examination proceedings lastyear.

Du Pont's outside counsel, E. Anthony Figg of Bernard,Rothwell and Brown, contended that Cetus' patent withdrawsPCR technology from public use. He argued that the technologyhas been in the public domain since the early 1970s, when Dr.H. Gobind Khorana and his co-workers developed it at theUniversity of Wisconsin.

Cetus' outside counsel, Lynn H. Pasahow of McCutcheon, Doyle,Brown and Enersen, argued that scientists could not haveperformed PCR by following Khorana's papers. Although PCRexponentially amplifies DNA, the reaction described by Khoranadoes not, he said. Khorana chose not to testify at this trial,Pasahow said.

Among the distinguished witnesses called to testify is ArthurKornberg, Stanford University professor emeritus, who isscheduled to appear today for Du Pont.

(For background on these cases, keyword search the IndustryLibrary for 010491CTUS, 110190DUPONT, 103090CTUS,102690CTUS, 082890CTUS, 061590PCR, 041690PCR,030690PCR, and 021590PCR.)

-- Carol Talkington Verser, Ph.D. Special to BioWorld

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