United States: Federal Circuit Upholds Inequitable Conduct Defense Against Apotex Patent

In Apotex Inc. v. UCB, Inc., the Federal Circuit upheld the district court's finding that Apotex's patent is unenforceable due to inequitable conduct. While affirming on the ground of "but-for materiality," the Federal Circuit noted that the inventor's conduct "at a minimum, come[s] close to the type of affirmative misconduct" that can "justify finding inequitable conduct without showing but-for materiality." This case also serves as a reminder that the USPTO still has not acted on its proposal to align Rule 56 with Therasense.

The Patent at Issue

The patent at issue was U.S. 6,767,556, directed to a method of making tablets of moexipril, which is an ACE inhibitor used to treat hypertension. Dr. Sherman is the sole inventor named on the '556 patent, the founder and chairman of Apotex, and "directs all litigation for Apotex."

Claim 1 is the only independent claim in the patent:

1. A process of making a solid pharmaceutical composition comprising moexipril magnesium, said process comprising the step of reacting moexipril or an acid addition salt thereof with an alkaline magnesium compound in a controlled manner in the presence of a sufficient amount of solvent for a predetermined amount of time so as to convert greater than 80% of the moexipril or moexipril acid addition salt to moexipril magnesium.

According to the Federal Circuit decision, moexipril is "susceptible to degradation and instability." The '556 patent addresses this problem by "making moexipril tablets consisting mostly of moexipril magnesium obtained by reacting moexipril or its acid addition salts with an alkaline magnesium compound." According to the patent, "the reaction cannot be accomplished in dry form and must be carried out in the presence of a solvent," using "wet granulation" methodology that "has been known in the pharmaceutical industry since at least the 1980s."

The Accused Products and Prior Art

The accused products were UCB's Univasc® and Uniretic® products, which were prior art to the '556 patent. Other prior art included U.S. Patent 4,743,450 which was listed in the Orange Book for the UCB products and which discloses a process that "involves the wet granulation of moexipril hydrochloride and magnesium oxide." The '450 patent cited a 1990 article by Gu et al. that discussed the mechanism by which alkaline stabilization of moexipril might occur.

The Prosecution History

The '556 patent and prosecution history distinguished the prior art by asserting that the prior art taught the use of an alkaline compound stabilizer in the final, solid product, while the claimed methods taught reacting moexipril with an alkaline magnesium compound to form moexipril magnesium.

For example, the '556 patent characterizes the '450 patent as teaching a stabilized solid product that includes an alkaline compound as stabilizer, and characterizes Gu as being "consistent with" the '450 patent and teaching "that only a portion (if any) of the drug, and only that portion at the outer surface of the granules, may be converted to the alkaline salt, and that the stable product thus results entirely or primarily not from conversion to alkaline salts, but from stabilization of the moexipril hydrochloride by the presence of the alkaline stabilizing compound in the final product."

The applicant asserted and emphasized these alleged differences throughout prosecution. For example, in one response the applicant argued:

The Examiner alleges that Gu et al. renders obvious the process of making moexipril magnesium and that Gu discloses a process of making a moexipril alkaline salt by allegedly reacting moexipril hydrochloride with an alkaline stabilizing agent. Respectfully no such reaction is taught. The components are merely combined and any reaction is insignificant to the desired end result.

The applicant submitted an expert Declaration attesting that a "stabilizer" (as taught in the '450 patent) would have to be unreacted to perform its intended function. Thus, a person of ordinary skill in the art "would ... not expect a reaction to occur between the ACE inhibitor and the alkaline stabilizer disclosed in the '450 patent."

The Examiner's Reasons for Allowance indicate that the patent was allowed on the basis of that alleged distinction:

The primary reason for allowance is that the prior art does not disclose nor fairly suggest a process of making a pharmaceutical composition comprising moexipril magnesium, comprising the step of reacting moexipril or an acid addition salt thereof with an alkaline magnesium compound so as to convert greater than 80% of the moexipril or moexipril acid addition salt to moexipril magnesium. Rather, the prior art teaches that only a portion of drug (if any) may be converted to the alkaline salt and that the stable product results entirely or primarily not from conversion to alkaline salts, but from stabilization of the moexipril hydrochloride by the presence of the alkaline stabilizing compound in the final product.

The District Court Decision

The district court found that the '556 patent "is unenforceable due to Dr. Sherman's inequitable conduct." As summarized in the Federal Circuit decision, the district court found that "Dr. Sherman was aware that Univasc was made according to his claimed process, concealed this knowledge from the PTO, and misrepresented the nature of Univasc and the prior art through his counsel's arguments and Dr. Lipp's declaration," and that "Dr. Sherman withheld relevant prior art and submitted results of experiments that he never conducted."

For example, shortly after the patent application was filed, "two Apotex scientists ... produced a detailed mass spectrometry report on Univasc and concluded that moexipril in Univasc is 'mainly present' as moexipril magnesium," but that information never was disclosed to the Patent Office. On the other hand, the patent included examples written in the past tense that were "made up in [Dr. Sherman's] head."

With regard to materiality, the district court found that the misinformation and withheld information was "but-for" material and, in the alternative, that Dr. Sherman had engaged in "egregious misconduct during prosecution." With regard to intent, the district court found that "the single most reasonable inference that could be drawn from the evidence was that Dr. Sherman intended to deceive the PTO."

The Federal Circuit Decision

The Federal Circuit decision was authored by Judge Reyna and joined by Judges Wallach and Hughes. The Federal Circuit determined that "the district court's findings regarding materiality and intent were "not clearly erroneous," and its "ultimate determination ... was not an abuse of discretion."

The Federal Circuit reviewed the facts outlined above, and found that "[c]lear and convincing evidence demonstrates that Dr. Sherman engaged in material misconduct." In this regard, the court noted that "Dr. Sherman was actively involved in the prosecution of the '556 patent and instigated the representations made on his behalf by his counsel and Dr. Lipp." Thus, the finding that "Dr. Sherman is responsible for the alleged misconduct is not clearly erroneous."

The Federal Circuit found that the misconduct was "'but-for' material to the issuance of the '556 patent," as shown by the course of prosecution and the Examiner's Reasons for Allowance. As set forth above, although the Federal Circuit did not decide whether Dr. Sherman's conduct amounted to "egregious misconduct" under Therasense, the Federal Circuit noted that the inventor's conduct "at a minimum, come[s] close to the type of affirmative misconduct" that can "justify finding inequitable conduct without showing but-for materiality."

The Federal Circuit also agreed that "clear and convincing evidence establishes Dr. Sherman's intent to deceive the PTO."

As of the filing of the '556 patent application, Dr. Sherman was aware that some of the assertions he made in the specification regarding the prior art were at least misleadingly incomplete, if not plainly inaccurate. Additionally, Dr. Sherman admitted that he never performed the experiments described in the '556 patent, and yet he drafted the examples in the specification entirely in past-tense language. ... Dr. Sherman was also aware that additional misrepresentations were made on his behalf to the PTO, and directed his counsel to bolster those misrepresentations by procuring and submitting the declaration of an expert who was deliberately shielded from the truth.

Responding to Apotex's arguments that "merely advocating a particular interpretation of the prior art cannot support an inference of deceptive intent," the Federal Circuit explained that "Dr. Sherman's statements were not mere advocacy for a preferred interpretation; his statements were factual in nature and contrary to the true information he had in his possession."

Thus, the Federal Circuit upheld the district court's finding that the '556 patent is unenforceable due to inequitable conduct.

What Constitutes Inequitable Conduct?

If my "inequitable conduct" blog articles are an accurate indication, this is the third case since Therasense where the Federal Circuit has upheld a finding of inequitable conduct. (In a fourth, the Federal Circuit remanded to the district court to make findings on intent.) In all of these cases, at least some of the misconduct at issue involved affirmative statements made during prosecution, not simply the failure to submit a prior art reference. Still, the PTO has not updated Rule 56 to conform to Therasense, even though it published proposed rule changes in 2011 that would do so.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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