Orange Book Blog

On November 20, 2006, the U.S. Court of Appeals for the Federal Circuit handed down its decision in Impax's case against Aventis related to Rilutek, which is marketed by Aventis for the treatment of Lou Gehrig's Disease (amyotrophic lateral sclerosis or ALS).  In the twelve months preceding August, 2006, Rilutek (riluzole) had U.S.sales approaching $37 million dollars.  Rilutek is the only FDA-approved treatment for ALS.

Impax filed an ANDA on March 16, 2001, to market a generic version of Rilutek and during the course of the approval process became aware of Aventis's U.S. Patent No. 5,527,814.  At the time, the '814 patent was not listed in the Orange Book, and thus Impax filed a declaratory judgment action seeking a declaration that it had not infringed the patent and asserting that the patent was invalid and unenforceable.

The Federal Circuit affirmed the district court's holding that the '814 patent was not unenforceable due to inequitable conduct, but vacated the lower court's holding that claims 1-5 of the '814 patent were anticipated by Aventis's own U.S. Patent No. 5,236,940, and remanded the case.

The lower court had found that even though the '940 patent disclosed riluzole as a member of a broad class of compounds, the '940 patent did not show riluzole's effectiveness in treating ALS and therefore it was not anticipatory.  Impax Labs v. Aventis Pharms., 333 F. Supp.2d 365 (D. Del. 2004).  The Federal Circuit disagreed with the lower court.  Citing Rasmusson v. SmithKline Beecham, the Federal Circuit stated that a prior art reference need not show utility in order to be anticipatory:

Under Rasmusson, the effectiveness of the prior art is not relevant . . . .  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.

Thus, the Federal Circuit remanded the case to the district court in Delaware for further proceedings under this statement of the test.

Interestingly, Judge Rader concurred with the majority on all points except the anticipation determination.  Judge Rader wrote:

While the trial court referred to effectiveness, its findings go beyond that narrow ruling and suffice to uphold its judgment.  For example, the district court noted first that formula I [of the '940 patent] encompasses a particularly large number of compounds.  In addition, the district court examined the specification of the '940 patent and determined that riluzole was not meaningfully discussed . . . .  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.  When it found that the disclosure leaves 'substantial uncertainty,' the trial court sufficiently supported its holding.  The '940 disclosure does not make [riluzole] a potential treatment in any way.

Thus, Judge Rader was inclined to affirm the district court's ruling on all counts.