The Court of Appeals for the Federal Circuit held that the effectiveness of the prior art is not relevant but rather whether it describes the claimed invention sufficiently to enable a person of ordinary skill in the art to carry out the invention.

After Impax sued Aventis in District Court for a declaratory judgment that Impax did not infringe, induce infringement of, or contribute to the infringement of U.S. Pat. No. 5,527,814 by filing an Abbreviated New Drug Application for the sale of riluzole, the district court found that Impax failed to prove the patent as invalid. Impax Laboratories v. Aventis Pharmaceuticals (05-1313).

Riluzole, sold under the name Rilutek, is the chemical compound 6-trifluoromethoxy-2-benzothiazolamine used for the treatment of patients with amyotrophic lateral sclerosis (“ALS”). ALS, commonly referred to as Lou Gehrig’s disease, is a disease of the central nervous system involving the progressive degeneration of the nerves that carry impulses to muscles.

Under 35 U.S.C. § 271(e)(2), it is an act of infringement to submit an ANDA under 21 U.S.C. § 355(j) for a drug claimed in a patent before the patent’s expiration. Therefore, Impax needs to knock out the ‘814 patent.

So, Impax asserted that the claims of the ’814 patent were invalid over the prior art and invalid by reason of incorrect inventorship. Impax later amended its complaint to add allegations of inequitable conduct.

In the district court Impax claimed that claims 1-5 of the ’814 patent were anticipated by the ’940 patent. The ’940 patent, which is owned by Aventis, is directed to a class of compounds disclosed in formula I:


The ’940 patent includes many different compounds, but it exempts 6-trifluoromethoxy-2-benzothiazolamine. That is, 6-trifluoromethoxy-2-benzothiazolamine could fall within the literal scope of formula I but is explicitly exempted from formula I. The ’940 patent states that 6-trifluoromethoxy-2-benzothiazolamine is not new, and thus does not form part of the invention. The ’940 patent goes on to state that the compounds of formula I are useful in treating medical conditions associated with the effects of glutamate such as ALS.

The ’940 patent claims priority from the ’624 application, which has a disclosure similar to that of the ’940 patent. However, the ’624 application does not exempt 6-trifluoromethoxy-2-benzothiazolamine from the family of formula I compounds as a claimed compound.

Impax argued that every limitation of claims 1-5 of the ’814 patent was disclosed by the ’940 patent in describing a class of compounds generally encompassed by formula I, including riluzole, and that the ’940 patent taught that riluzole is useful in treating ALS and also taught effective administration.

Aventis argued that the ’940 patent excluded riluzole from the compounds and that even if the ’940 patent included riluzole, it did not anticipate the ’814 patent because it failed to disclose the invention in the ’814 patent and was not enabling because it did not provide specific instruction for using riluzole and actually taught away from riluzole.

The district court concluded that the ’814 patent was not anticipated because “formula I entails 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 that is not found in the disclosure of the ’940 patent.” Therefore, the court reasoned, formula I was not enabling.

In order to be anticipating, a prior art reference must be enabling so that the claimed subject matter may be made or used by one skilled in the art. Prior art is not enabling so as to be anticipating if it does not enable a person of ordinary skill in the art to carry out the invention.

The CAFC held that:

The enablement requirement for prior art to anticipate under section 102 does not require utility, unlike the enablement requirement for patents under section 112. Rasmusson v. SmithKline Beecham Corp., 413 F.3d 1318, 1325-26 (Fed. Cir. 2005) … Significantly, we have stated that ‘anticipation does not require actual performance of suggestions in a disclosure. Rather, anticipation only requires that those suggestions be enabled to one of skill in the art.’” (citations omitted).

“Whether a prior art reference is enabling is a question of law based upon underlying factual findings.” Minn. Mining & Mfg. Co. v. Chemque, Inc., 303 F.3d 1294, 1301 (Fed. Cir. 2002). In Amgen, we stated that, when, as here, an accused infringer asserts that either claimed or unclaimed material in a prior art patent anticipates patent claims asserted against it, the infringer is entitled to a presumption that the allegedly anticipating material is enabled.

The district court found that the ’940 patent did not anticipate the ’814 patent because the disclosure of the ’940 patent was not enabling at least in part because there was no evidence that it would be “effective.” Id. Under Rasmusson, the effectiveness of the prior art is not relevant. Id. Rather, the proper issue is 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. The CAFC then remanded to allow the district court to make a factual determinations and then reach its own legal conclusion as to whether the ’940 patent is enabled.

The CAFC thought differently, however, of the ‘624 patent holding:

As found by the district court, riluzole is just one of hundreds of compounds included in formula I. 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 (C.C.P.A. 1962). If the members cannot be envisioned, the reference does not disclose the species and the reference is not enabling. Here, with the large number of compounds included in formula I and no specific identification of riluzole by the ’624 application, the ’624 application does not disclose riluzole, and therefore, cannot enable treatment of ALS with riluzole. The ’624 application cannot anticipate any of claims 1-5 of the ’814 patent.

Judge Rader, concurring in part, opined that:

[T]he court determined that the language of the ‘940 patent itself created “substantial uncertainty” regarding use of glutamate inhibiting compounds in the treatment of ALS. Id. The court determined that the language in the patent discussing conditions implicating glutamate to be speculative, at best. Id. Thus, I read the district court to have found that the ‘940 disclosure did not put one of skill in the art in possession of the invention at all. Elan Pharms., Inc. v. Mayo Found., 346 F.3d 1051, 1057 (Fed. Cir. 2003). When it found that the disclosure leaves “substantial uncertainty,” the trial court sufficiently supported its holding. Id. The ‘940 disclosure does not make it a potential treatment in any way.

Anticipation does not require proof of “utility,” or (in other words) “actual performance of suggestions in a disclosure,” Bristol-Myers Squibb Co. v. Ben Venue Labs., 246 F.3d 1368, 1378 (Fed. Cir. 2001), but in this case, the district court has found that the disclosure does not make even a suggestion of disclosure to one of skill in the art. Beyond the efficacy question, the ‘940 patent does not even disclose the necessary suggestion to enable one of ordinary skill in the art to look to riluzole for the treatment of ALS in the first place. Thus, I would affirm the district court’s determination of anticipation without requiring a remand in this case.

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