Federal Circuit Finds That Mere Disclosure of Genus in Prior Art Does Not Enable Species for Purposes of Anticipation Unless Species Can be envisioned

In Impax Laboratories, Inc. v. Aventis Pharmaceuticals Inc., 81 USPQ2d 1001 (Fed. Cir. 2006), Impax sued Aventis for a declaratory judgment arguing that, by filing an Abbreviated New Drug Application (ANDA), Impax did not infringe, induce infringement of, or contribute to the infringement of U.S. Patent No. 5,527,814 (the ‘814 patent) owned by Aventis. The Federal Circuit evaluated whether Impax failed to prove (1) that the ‘814 patent was unenforceable due to inequitable conduct, and (2) that the ‘814 patent was invalid as anticipated. In an opinion by Judge Schall, the Federal Circuit found (1) that there was no inequitable conduct in the prosecution of the ‘814 patent, and (2) that the District Court incorrectly analyzed the ‘814 patent with regard to anticipation.

Aventis owns the ‘814 patent, which claims priority to U.S. Patent Application Serial No. 07/945,789 filed September 16, 1992. Five claims of the ‘814 patent were at issue, the first of which recites a method for treating amyotrophic lateral sclerosis (ALS) by administering to a mammal in recognized need of treatment “an effective amount of [riluzole] or a pharmaceutically acceptable salt thereof.” Claims 2 and 3 recite limitations regarding treating ALS in the bulbar muscles of the throat, tongue, and respiratory system. Claims 4 recites that the effective amount of the compound being administered should be 25 to 200 mg, and claim 5 depends upon and narrows claim 4 to administering 50 mg. ALS is more commonly known as Lou Gehrig’s disease.

Under 35 U.S.C. §271(e)(2), it is an act of infringement to file an ANDA if the purpose of such submission is to obtain approval for commercial manufacture, use, or sale of a drug that is claimed in patent or the use of which is claimed in a patent before the expiration of such patent. On March 16, 2001, Impax filed an ANDA with the FDA seeking approval to market and sell generic riluzole tablets for treatment of ALS. Impax discovered the ‘814 patent during prosecution of the ANDA, and on June 25, 2002, Impax filed the declaratory judgment that was the basis for this Federal Circuit’s opinion. On January 29, 2003, the FDA approved Impax’s ANDA.

Impax alleged that the ‘814 patent was invalid as anticipated by U.S. Patent 5,236,940, (the ‘940 patent) which claimed priority from French Application No. 2,640,624 (the ‘624 application). Under 35 U.S.C. §102(b), a patent claim is invalid as anticipated if every limitation in a claim is found in a single prior art reference, either explicitly or inherently. As such, the prior art reference must enable one of ordinary skill in the art to make or use the claimed invention. However, the enablement requirement for anticipation purposes does not require utility as is required for enablement with regard to written disclosures under 35 U.S.C. §112.

The ‘940 patent, which is also owned by Aventis, claimed a formulaic compound that would include riluzole; however, the ‘940 patent specifically exempts the formula for riluzole stating that riluzole is not new and not part of the claimed invention. The ‘624 application contains a substantially similar disclosure but does not exempt riluzole. The Court analyzed each reference in turn.

With regard to the ‘940 patent, the District Court found that the ‘940 patent did not anticipate the ‘814 application as the formula disclosed in the ‘940 patent “entail[ed] such a large number of compounds… [that] one of ordinary skill in the art would not have recognized that riluzole was effective in treating ALS without additional detail or guidance” not contained therein. The District Court found that despite the ‘940 patent disclosing riluzole, suggesting that riluzole could be used to treat ALS, providing dosage information that the ‘814 patent was not anticipated by the ‘940 patent as the ‘940 patent provided “no evidence that [riluzole] would be effective,” thus, the ‘814 patent was not sufficiently enabled.

The Federal Circuit, relying on Rasmusson v. SmithKline Beecham Corp. 413 F.3d 1318 (Fed. Cir. 2005), rejected such analysis as effectiveness is not required to be shown for enablement analysis for the purposes of anticipation. The Federal Circuit framed the issue as “whether the ‘940 patent is enabling in the sense that it describes the claimed invention sufficiently to enable a person of ordinary skill in the art to carry out the invention.” On such a finding, the Federal Court reversed the District Court’s decision and remanded for further analysis.

The District Court analyzed the ‘624 application in the same manner as the ‘940 patent as both the plaintiff and defendant provided substantially similar arguments with respect to each. However, the Federal Circuit employed a different analysis since there were material differences between the ‘940 patent and the ‘624 application. The ‘624 application does not name riluzole and only includes riluzole as one of hundreds of compounds within the formulaic compound disclosed. The Federal Circuit recognized that in order to enable a member of a class of compounds – or a species of a genus, one of ordinary skill in the art should be able to at once envisage each species of the genus.  Specifically, the Federal Circuit held that the general rule for enablement is as follows:

“When a reference discloses a class of compounds, i.e., a genus, a person of ordinary skill in the art should be able to “at once envisage each member of th[e] … class” for the individual compounds, i.e., species, to be enabled. In re Petering, 301 F.2d 676, 681 [133 USPQ 275] (C.C.P.A. 1962). If the members cannot be envisioned, the reference does not disclose the species and the reference is not enabling.” 81 USPQ2d at 1013.

The Federal Circuit found that with such a large number of compounds included in the ‘624 application and no specific identification of riluzole, the ‘624 application could not anticipate any of the claims of the ‘814 patent.

No inequitable conduct when advanced arguments exclude information not relevant to an Examiner’s rejection

Impax also alleged that the ‘814 patent was unenforceable due to inequitable conduct during prosecution. The Court required that Impax provide clear and convincing evidence of (1) affirmative misrepresentations of a material fact, failure to disclose material information, or submission of false material information, and (2) an intent to deceive. The standard for materiality may be met, as the Court discussed in Digital Control Inc. v. Charles Machine Works, 437 F.3d 1309 (Fed. Cir. 2006), under five different tests:

  1. Present USPTO Rule 56 – information is material if it establishes a prima facie case of unpatentability of a claim, or refutes or is inconsistent with arguments advanced by the applicant;
  2. Past USPTO Rule 56 – information is material if a “reasonable examiner” would have considered such information important in determining patentability;
  3. Objective “but for” standard – where the misrepresentation was so material that the patent should not have issued;
  4. Subjective “but for” standard – where the misrepresentation actually caused the examiner to approve the patent application when he would not otherwise have done so; and
  5. “But it may have” standard – where the misrepresentation may have influenced the examiner in the course of prosecution.

Upon a finding of materiality, the equities must be balanced to determine whether the patentee committed such conduct that warrants holding the patent unenforceable. “The more material the omission or misrepresentation, the less intent that must be shown to elicit a finding of inequitable conduct.” Bristol-Myers Squibb Co. v. Rhone-Poulenc Rorer, Inc., 326 F.3d 1226, 1234 (Fed. Cir. 2003). Furthermore, if inequitable conduct occurred in the prosecution of one claim, the entire patent is unenforceable.

Here, Impax alleged that Aventis failed to disclose material information during the prosecution of the ‘814 patent by withholding data generated by experiments involving riluzole. Impax argued that the withheld data was material as the data was inconsistent with arguments advanced by Aventis in support of patentability. Specifically, in 1993 and 1994, Aventis tested riluzole and seven other compounds for effectiveness in treating ALS as judged by several parameters. During the prosecution of the ‘814 patent, Aventis argued that the test results of riluzole and only 2 of the 7 compounds indicated that riluzole demonstrated unexpected results while not providing information on the tests of the other 5 of the 7 compounds. Impax alleged that the results of the 5 not disclosed compounds were material and inconsistent as some of the 5 compounds demonstrated better qualities for at least a few parameters than the 2 disclosed compounds. Thus, as Impax argued, as several of the compounds tested exhibited beneficial qualities as predicted by the prior art, the results with respect to riluzole were not unexpected.

However, the Federal Circuit found no error in the District Court’s decision as the tests were not material even though some of the compounds showed beneficial qualities. The Court found that no prima facie case of unpatentability was established as there was no indication that the test results demonstrated that the undisclosed compounds were effective in treating ALS. The Federal Circuit further found that Aventis’s argument was not inconsistent as Aventis had argued that riluzole demonstrated unexpected results over compounds disclosed in the ‘940 patent and that the 2 disclosed compounds of the 7 tested were similar to the compounds in the ‘940 patent. Also, there was no evidence of that a “reasonable examiner” would find such irrelevant test data important to the determination of patentability of the application. The Court only applied the Present and the Past USPTO rules 56 and did not analyze materiality under the two “but for” or the “but it may have” standards. However, the three ignored standards remain valid.

The Federal Circuit found that the above reasoning – attempting to overcome prior art – indicated that there was no intent to deceive as the disclosed tests were relevant to distinguishing over the ‘940 patent while the undisclosed tests were not relevant. As such, the Federal Circuit found no clear error in the lower court’s finding of no inequitable conduct.


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