Aventis smokes Impax at CAFC on riluzole case

Impax, represented by Kenyon & Kenyon, appealed a decision of Judge Farnan of D. Del. to the CAFC, and lost. In the case, issues of enablement of an asserted prior art patent, US 5,236,940, were argued.

Impax had asserted that the '940 anticipated claims 1-5 of U.S. Patent No. 5,527,814 of Aventis, which patent relates to the use of riluzole (Aventis proprietary name: RILUTEK) to treat amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease). The issue of "undue experimentation" arose -->

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. Finisar
Corp. v. DirecTV Group, Inc., 523 F.3d 1323, 1336 (Fed. Cir. 2008) (citing In re
Omeprazole Patent Litig., 483 F.3d 1364, 1379 (Fed. Cir. 2007)). In other words, the
prior art must enable the claimed invention. Minn. Mining & Mfg. Co. v. Chemque, Inc.
(3M), 303 F.3d 1294, 1301 (Fed. Cir. 2002). The “undue experimentation” component
of that equation examines (1) the quantity of experimentation; (2) the amount of
direction or guidance present; (3) the presence or absence of working examples; (4) the
nature of the invention; (5) the state of the prior art; (6) the relative skill of those in the
art; (7) the predictability or unpredictability of the art; and (8) the breadth of the claims.
In re Wands, 858 F.2d 731, 737 (Fed. Cir. 1988).

The CAFC reviewed the findings -->

In view of these findings, the district court found that one of ordinary skill in the
pharmaceutical arts would have needed extensive experimentation to link riluzole with
the treatment of ALS. Id. at 433. The district court then reached the ultimate conclusion
that the ’940 patent does not enable claims 1-5 of the ’814 patent and thus, it is not
anticipatory.

This court does not find error, let alone clear error, in the district court’s factual
findings. Weighing the Wands factors, the trial court's findings properly support its
conclusion that an ordinarily skilled artisan would have needed to experiment unduly to
gain possession of the invention. Smokin'!

Of the specific problems with the prior art -->

As shown by the trial court, the '940 patent's dosage
guidelines are broad and general without sufficient direction or guidance to prescribe a
treatment regimen. The alleged prior art also contains no working examples. Finally,
nothing in the '940 patent would have led one of skill in the art to identify riluzole as a
treatment for ALS.

Of evidentiary burdens -->

As this court explained during the first appeal, when an accused infringer asserts
that a prior art patent anticipates specific patent claims, the infringer enjoys a
presumption that the anticipating disclosure also enables the claimed invention. Impax
Labs., 468 F.3d at 1382. However, the patentee may overcome that presumption with
persuasive evidence showing that the prior art patent does not enable the claimed
invention. Id. On appeal, Impax argues that the district court’s silence regarding the
initial presumption of enablement to both claimed and unclaimed material is reversible
legal error. For this proposition, Impax cites this court's opinion in Amgen Inc. v.
Hoechst Marion Roussel, Inc., 314 F.3d 1313, 1355-56 (Fed. Cir. 2003).

To the contrary, in Amgen, the district court placed an affirmative burden of
proving the prior art reference’s enablement of the claimed invention on the alleged
infringer. Id. This court assigned error to that shifting of the burden. In this case, the
district court correctly placed the burden of proving non-enablement on the patentee.
The patentee then met that burden with persuasive evidence that the ’940 patent does
not enable claims 1-5 of the ’814 patent. The district court did not need to specifically
articulate its correct burden-shifting framework. In this case, as the district court found,
the record shows sufficient evidence to overcome the presumption of enablement.

On previously considered prior art -->

An issued patent enjoys a presumption of validity. Impax Labs., 468 F.3d at
1378. Thus, a party challenging patent validity has the burden to prove its case with
clear and convincing evidence. Id. When the examiner considered the asserted prior
art and basis for the validity challenge during patent prosecution, that burden becomes
particularly heavy. See Hewlett-Packard Co. v. Bausch & Lomb Inc., 909 F.2d 1464,
1467 (Fed. Cir. 1990).