Aventis' Patent for Lou Gehrig Disease Drug Valid, Federal Circuit Finds

Holding:

Aventis' patent relating to the treatment of the Lou Gehrig disease is valid, so determines the U.S. Court of Appeals for the Federal Circuit in ruling against generics drug maker Impax Laboratories, Inc. ("Impax"). In its complaint seeking among others to declare as invalid Aventis' patent-at-issue, Impax argued that an earlier Aventis patent (the '940 patent) anticipates the asserted Aventis patent (the '814 patent) by suggesting a class of compounds may be used to treat the disease. The U.S. District Court for the District of Delaware however found that the '940 patent does not enable a person of ordinary skill in the art to treat the disease with Aventis' patented drug compound and therefore does not anticipate certain claims of the '814 patent. On appeal, the Federal Circuit affirmed, citing the rule that in order to anticipate a claimed invention, a prior art reference must enable one of ordinary skill in the art to make the invention without undue experimentation. Here, the district court's findings properly supported its conclusion that an ordinarily skilled artisan would have to unduly experiment to gain possession of the invention. The '940 patent's dosage guidelines are broad and general without sufficient direction or guidance to prescribe a treatment regimen.

Detailed Summary:

The ’814 patent relates to the use of riluzole to treat amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease). Aventis Pharmaceuticals Inc. (“Aventis”) owns the ’814 patent and sells riluzole under the trade name RILUTEK. Opinion, p. 1. On May 16, 2001, Impax filed with the Food and Drug Administration (FDA) an Abbreviated New Drug Application (ANDA) pursuant to 21 U.S.C. 355(j) seeking approval to market generic riluzole tablets. On June 25, 2002, Impax sued Aventis in the district of Delaware for a declaratory judgment that Impax did not infringe, induce infringement of, or contribute to the infringement of the ’814 patent. In its suit, Impax alleged that the ’814 patent was invalid and unenforceable.

After a bench trial, the district court determined that Impax did not prove that the ’814 patent was unenforceable due to inequitable conduct nor show that claims 1-5 were anticipated by prior art. Id., p. 2, citing Impax Labs., Inc. v. Aventis Pharms. Inc., 333 F. Supp. 2d 265 (D. Del. 2004). On March 16, 2005, the district court entered final judgment against Impax.

Impax appealed that decision. The Federal Circuit affirmed-in-part, vacated-in-part, and remanded to the district court. Id., citing Impax Labs., Inc. v. Aventis Pharms. Inc., 468 F.3d 1366, 1384 (Fed. Cir. 2006). On remand, the district court examined the asserted prior art, the ’940 patent, for evidence that it enables the use of riluzole to treat ALS and thus qualifies as enabling prior art. Id., citing Impax Labs., Inc. v. Aventis Pharms. Inc., 496 F. Supp. 2d 428, 433 (D. Del. 2007). Addressing those questions, the district court determined that the ’940 patent does not enable a person of ordinary skill in the art to treat ALS with riluzole and therefore does not anticipate claims 1-5 of the ’814 patent. Id. Impax timely appealed the district court’s remand decision to this court.

The issue in this appeal is whether the asserted prior art, the ’940 patent,  enables the use of riluzole to treat ALS and thus qualifies as enabling prior art. In resolving this issue in favor of Adventis, the Federal Circuit took note of the rule that a party challenging patent validity has the burden to prove its case with clear and convincing evidence. Id., p. 3, citing Impax Labs., 468 F.3d at 1378.

When the examiner considered the asserted prior art and basis for the validity challenge during patent prosecution, that burden becomes particularly heavy. Id., referring to Hewlett-Packard Co. v. Bausch & Lomb Inc., 909 F.2d 1464, 1467 (Fed. Cir. 1990). In order to anticipate a claimed invention, a prior art reference must enable one of ordinary skill in the art to make the invention without undue experimentation. Id., citing Finisar Corp. v. DirecTV Group, Inc., 523 F.3d 1323, 1336 (Fed. Cir. 2008).

Here, the district court found that excessive experimentation would have been necessary to practice the invention. Id., p. 4. Specifically the district court opined that formula I of the alleged prior art discloses hundreds or thousands of compounds and several diseases. Id. Moreover, nothing in the ’940 patent would direct one skilled in the art to recognize that riluzole could be used to treat ALS.

The Federal Circuit did not find error in these findings. The district court’s findings properly supported its conclusion that an ordinarily skilled artisan would have needed to experiment unduly to gain possession of the invention. Id., p. 5. As shown by the district court, the ‘940 patent’s dosage guidelines are broad and general without sufficient direction or guidance to prescribe a treatment regimen. Id. The alleged prior art also contains no working examples. Id. Finally, nothing in the ‘940 patent would have led one of skill in the art to identify riluzole as a treatment for ALS. In sum, each component of the claimed invention—identifying riluzole as a treatment for ALS and devising dosage parameters—would require undue experimentation based on the teachings of the ‘940 patent. Because the ’940 patent does not enable a person of ordinary skill in the art to treat ALS with riluzole, it does not anticipate claims 1-5 of the ’814 patent.

On the basis of the foregoing, the Federal Circuit affirmed the district court’s dismissal of Impax’s invalidity challenge against the patent-at-issue.

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