General disclosure in prior art not enabling for specific pharmaceutical compound's use in treatment

October 07, 2008
Post by Blog Staff

In a decision last week, the Federal Circuit affirmed a district court's holding that a prior art patent was not enabling and thus did not anticipate the patent-in-suit. Applying the In re Wands factors, the district court held undue experimentation would be required in order to produce the claimed invention based on the prior art's disclosure. The Federal Circuit affirmed, and observed the asserted prior art was broad and general without sufficient direction to practice the claimed invention. Moreover, the asserted prior art provided no working examples of the invention claimed in the patent-in-suit. Finally, the court held the district court correctly placed the burden of proving non-enablement on the patentee, given the prior art reference was an issued U.S. Patent, but it was not necessary for the district court to specifically articulate its burden-shifting framework.More on Impax Labs, Inc. v. Aventis Pharms Inc., after the jump.

Aventis owns a patent relating to use of riluzole to treat amyotrophic lateral sceloris (ALS or Lou Gehrig's disease). Aventis sells riluzole under the trade name Rilutek.Impax specializes in generic and branded pharmaceutical products to be used, for instance, in treating central nervous disorders. On May 16, 2001, Impax filed an Abbreviated New Drug Application (ANDA) seeking approval to market generic riluzole. Impax filed a declaratory judgment action against Aventis alleging the patent was not infringed, invalid, and unenforceable.After a bench trial, the district court ruled that Impax did not prove the patent was unenforceable or anticipated. Impax appealed. On appeal, the Federal Circuit affirmed-in-part, vacated-in-part, and remanded for consideration of whether the asserted prior art enabled use of riluzole to treat ALS.On remand, the district court held the asserted prior art did not enable a person of ordinary skill in the art to treat ALS with riluzole, and therefore could not anticipate. The district court noted the prior art patent discloses hundreds or thousands of compounds and several diseases that may be treated by the disclosed compounds. As a result, nothing in the prior art patent would direct a person of ordinary skill to recognize riluzole specifically could be used to treat ALS. Finally, the court noted the absence of working examples and specific dosing information. Based on this disclosure, the district court held undue experimentation would have been required to produce the claimed invention based on the prior art's disclosure. Impax appealed.The Federal Circuit affirmed. The court noted it could "not find error, let alone clear error, in the district court's factual findings." The court agreed that under In re Wands, one of ordinary skill in the art would have to engage in undue experimentation to gain possession of the invention. The prior art patent did not contain any working examples, identify riluzole as a treatment for ALS, or provide dosage parameters.The court also rejected Impax's assertion that the district court erred in not indicating explicitly that it had placed the burden of proving non-enablement on Aventis. When a prior art patent forms the basis for an assertion of invalidity, the patent is presumed to enable the claimed invention. Impax argued the district court remained silent as to allocating the burden of proving non-enablement to Aventis, and this was reversible error.The court easily rejected this argument. The court determined the district court correctly placed the burden of proving non-enablement on the patentee in this case. The patentee, according to the court, had then met that burden with persuasive evidence that the prior art patent was not enabling. As stated by the court: "The district court did not need to specifically articulate its correct burden-shifting framework."As a result, the court affirmed the district court's holding that the prior art patent was enabling and therefore did not anticipate the patent-in-suit.To read the full decision in Impax Labs, Inc. v. Aventis Pharms Inc., click here.

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