The U.S. Court of Appeals for the Federal Circuit, in Aventis Pharma S.A. v. Amphastar Pharmaceuticals, Inc., and Teva Pharmaceuticals Usa, Inc., (No. 05-1513; April 10, 2006), held that if there is another reasonable inference for not disclosing information during prosecution, the failure to disclose may have been due purely to inadvertence.

In the case, Aventis appealed a District Court summary judgment in favor of Amphastar Pharmaceuticals and Teva Pharmaceuticals that held U.S. Pat. No. 5,389,618 and Reissue Patent No. 38,743 unenforceable. The ’618 patent and the ’743 reissue patent disclose and claim mixtures of low molecular weight herapin (“LMWH”) used to prevent blood clots and sold as Lovenox® (enoxaparin sodium injection). During prosecution of the application leading to the ’618 patent and the ’743 reissue patent, Aventis compared the half-life of a product allegedly covered by the ’618 patent at a 40 mg dose to the half-life of a prior art product at a 60 mg dose to show an unexpected and significantly better half-life. Aventis did not, however, expressly disclose the dosages at which the half-life comparisons were made, and specifically, that the EP 40,144 LMWH data was for a 60 mg dose.

The district court faulted Aventis for comparing data based on different doses to show an improved half-life, when a comparison of available data using the same doses actually showed that there was little if any difference between the half-lives of the prior art and the purported invention. Aventis argued that the use of the 40 mg Debrie LMWH data, as opposed to the 60 mg Debrie LMWH data, was reasonable. The court stated that the question is not whether use of the 40 mg data was reasonable, but whether there was an omission of material fact, particularly in light of the fact that the same study showed that the 60 mg Debrie LMWH data and the 60 mg EP 40,144 LMWH data was much closer than the 40 mg Debrie LMWH data and the 60 mg EP 40,144 LMWH data. It therefore granted summary judgment of unenforceability due to inequitable conduct.

The standards for finding inequitable conduct as follows:

Applicants for patents have a duty to prosecute patents in the PTO with candor and good faith, including a duty to disclose information known to the applicants to be material to patentability. A breach of this duty may constitute inequitable conduct, which can arise from an affirmative misrepresentation of a material fact, failure to disclose material information, or submission of false material information, coupled with an intent to deceive or mislead the PTO.

Purdue Pharma L.P. v. Endo Pharm., Inc., 438 F.3d 1123, 1128-29 (Fed. Cir. 2006) (citations omitted).

The threshold showing of materiality required to proceed to the “balancing” portion of the inequitable conduct inquiry can be met by showing a reasonable examiner would have considered such information important in deciding whether to allow the application.

The district court determined that an omission that would have revealed that the difference in half-lives was actually much smaller was material to patentability. A comparison made at the same dosage, 60 mg, would have yielded a much smaller difference in half-life. Given the centrality of the differences in half-lives to patentability, by failing to disclose the dosage of the 60 mg compound or to disclose that the difference in half-lives at the same dosage was actually lower, Aventis failed to disclose material information to the PTO.

The CAFC held that it was insufficient to merely submit the underlying data to the examiner and later argue that the examiner could have requested the EP 40,144 dosage information to make additional comparisons. The withholding of the EP 40,144 dosage information prevented the examiner from considering information important in deciding whether to allow the application, and was therefore a failure to disclose material information to the PTO.

Even if an omission is found to be material, the omission must also be found to have been made with the intent to deceive. On summary judgment, to create a genuine issue of material fact, Aventis was required to state specific facts supporting a plausible justification or excuse for its failure to disclose material information.

The CAFC stated that:

Here, the district court did not find direct evidence of intent to deceive, but found that the “facts and circumstances surrounding the failure to disclose the dose differential . . . supports a strong inference of intent by Aventis to deceive the PTO.” … Because Aventis has met its burden of setting forth a plausible justification for its failure to disclose material information, deciding all inferences in favor of Aventis, we hold that the district court erred in finding intent to deceive on summary judgment.

The district court’s inference was reasonable—by failing to disclose that the EP 40,144 data was at a 60 mg dose, Aventis may have been painting the rosiest picture possible as to the half-life improvement of its claimed compounds in an attempt to deceive the examiner. Appellees contend that this is only reasonable inference to draw from the facts presented. However, there is another reasonable inference—namely, as Aventis argues, if the comparison between different doses was reasonable, the failure to disclose may have been due purely to inadvertence. Based on the facts presented by Aventis, these are not “insupportable, [or] specious . . . explanations or excuses.” … Therefore, a finding of intent was inappropriate on summary judgment.

The CAFC then remanded for further proceedings stating there remain genuine issues of material fact regarding Aventis’s intent to deceive the PTO.

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