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Inventors’ Misrepresentations Lead to Inequitable Conduct

March 31, 2003

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Last Month at the Federal Circuit - April 2003

Judges: Bryson (author), Archer, and Newman (dissenting)

In Hoffmann-La Roche, Inc. v. Promega Corp., No. 00-1372 (Fed. Cir. Mar. 31, 2003), the Federal Circuit sustained certain findings of inequitable conduct but vacated the district court’s order of unenforceability and remanded for further consideration of the unenforceability holding given the Court’s ruling.

Cetus Corporation (“Cetus”), the predecessor of Hoffmann-La Roche, Inc. and Roche Molecular Systems, Inc. (collectively “Roche”), filed U.S. Patent Application No. 07/063,509 (“the ‘509 application”), which was directed to a purified thermostable enzyme that could be used in polymerase chain reaction (“PCR”). During its prosecution, the ‘509 application was rejected on various grounds, including anticipation/obviousness based on two journal articles, both of which disclosed a DNA polymerase derived from the Thermus aquaticus, or “Taq” bacterium, which is stable and active at high temperatures.

In response, the inventors entered new claims reciting purified thermostable Taq DNA polymerase having a specific molecular-weight range. They also made a two-part argument for patentability: (1) the claimed enzyme was distinct from the prior art enzyme, citing differences in molecular weight, specific activity, and fidelity; and (2) the claimed enzyme was far more pure than the prior art enzyme. Thereafter, the ‘509 application issued as U.S. Patent No. 4,889,818 (“the ‘818 patent”).

Cetus licensed the ‘818 patent to Promega Corporation (“Promega”) and later sold it to Roche. Roche sued Promega, alleging breach of the license agreement. Promega counterclaimed, asserting that the ‘818 patent was unenforceable due to inequitable conduct. After a bench trial, the district court held that the ‘818 patent was unenforceable based on (1) misrepresentations regarding the difference in molecular weight between the claimed and prior art Taq enzymes; (2) misrepresentations that the inventors had performed Example VI, one of the procedures described in the specification, and that they had achieved the described results; and (3) misrepresentations concerning the comparative fidelity of the claimed enzyme and the prior art enzymes.

During the prosecution of the ‘509 application, the inventors argued that the claimed enzyme with a molecular weight of 86,000 to 90,000 daltons was different from the prior art enzymes with molecular weights of 60,000 to 68,000 daltons, which they believed, at most, had been a crude preparation of degraded Taq polymerase. One issue over the disparity in molecular weights related to one inventor’s experiment where she observed that a Taq fragment with a molecular weight of 62,000 daltons did not bind to a phosphocellulose column. In the district court’s view, the fact that the Taq fragment did not bind to the phosphocellulose column indicated that a similar fragment would have been lost in the prior art experiment, because that experiment also used the same material. The district court concluded that the experiment suggested that the prior art enzymes were not simply degraded fragments of Taq polymerase and the inventors withheld that information from the PTO. The Federal Circuit disagreed because the experiment had been conducted under salt conditions (80 mM) very different from those described in the prior art reference (10 mM), which was critical to the capacity of the fragment to bind to the column. Since the results of the experiment were not pertinent to the inventors’ characterization of the prior art enzyme, the Federal Circuit held that the experiment was not material and the inventors had no intent to deceive.

The district court also ruled that the inventors improperly withheld information that suggested that the prior art technique was inaccurate and produced results underestimating the true molecular weight, which could weaken the inventors’ argument that the claimed enzyme was distinct from the prior art enzyme. The Federal Circuit reversed the district court’s ruling because none of the cited information suggested that the inventors knew the defects of the prior art technique.

The next issue was directed to Example VI of the ‘509 application, which was a procedure for repeatedly refining, or fractionating, a bacterial culture of the Taq enzyme through a variety of techniques, including column chromatography, thereby producing a purified version of the claimed enzyme. The Federal Circuit noted that Example VI was written in the past tense, suggesting that the test had been performed, but agreed that the test had not been performed as written in light of the testimony adduced at trial.

Roche also suggested that the use of the past tense in Example VI was not really a misrepresentation since all of the steps in that procedure had in effect been performed through the combination of two preparatory steps, Prep 3 and Prep 4, which Roche had actually performed. However, Roche offered no evidence contradicting Promega’s argument that the results of Prep 3 and Prep 4 would not provide an accurate representation of the results of a procedure conducted according to Example VI.

The Federal Circuit found intent because the inventors had attested that all statements in the ‘509 application had been true and Roche had not introduced any other evidence explaining why the past tense had been used to describe an experiment that had not been performed.

Roche also argued that because the ‘818 patent did not include claim limitations directed to purity, representations about purity made in the application could not be material. The Federal Circuit, however, found the information regarding Example VI material because the purity results reported in Example VI and the reference to them in the office action response had been central enough to the prosecution to be within a reasonable examiner’s realm of consideration.

The last issue was directed to the inventors’ representation that their claimed enzyme exhibited high fidelity compared to the prior art enzyme. The Federal Circuit upheld the district court’s finding that the statements characterizing the activity of the prior art enzymes and comparing it to that of the claimed enzyme were inaccurate because Promega’s expert witness testified that the differing results related to differences in experimental conditions and not to differences in the properties of the enzymes. Roche argued that the inventors and the expert simply differed over how to interpret the results of the experiments involving the prior art and claimed enzymes, and that a dispute of that sort could not give rise to a finding of inequitable conduct. The Federal Circuit disagreed and noted that Roche failed to make a persuasive showing that there was a legitimate difference of scientific opinion on that issue.

The Federal Circuit upheld the district court’s finding of materiality with respect to the fidelity issue because the fidelity statement in the office action response had been made in an effort to support the inventors’ primary argument for patentability—that the claimed enzyme was different from the prior art enzyme, even though the most prominent evidence cited by the inventors in this regard was a difference in molecular weight. The Federal Circuit also supported the district court’s finding that the statements about fidelity were intentionally deceptive, based primarily on expert testimony that one inventor had knowledge of the fidelity issue and could not possibly have believed that the experiments indicated that the prior art enzyme was promiscuous and inferior in fidelity.

The Federal Circuit vacated the finding of inequitable conduct, however, and stressed that the district court must now determine whether the material misrepresentations or omissions in question were sufficiently serious in light of the evidence of intent to deceive, under all the circumstances, to warrant the severe sanction of holding the patent unenforceable. Since the district court had not expressly addressed this determination, and the Federal Circuit did not uphold all of the grounds on which the district court had found inequitable conduct, the Federal Circuit vacated the district court’s unenforceability order and remanded the case for further proceedings.

Judge Newman dissented, concluding that the majority had expanded the substantial grounds of inequitable conduct by finding misrepresentations in correct science, inferring malevolence from verb tense, and grounding intent to deceive on personal slurs by a hostile witness.