In a patent battle over the world’s top-selling drug, the U.S. Court of Appeals for the Federal Circuit affirmed a district court holding that a claim cannot be constructed contrary to the specification or construed to import a limitation from the specification. However, the Court reversed part of the district court decision, holding that in order to be valid, a claim must meet all statutory requirements, including § 112, ¶ 4. Pfizer Inc. v. Ranbaxy Laboratories Limited, Case No. 06-1179 (Fed. Cir. Aug. 2, 2006) (Michel, C.J.).
Pfizer's Lipitor® (atorvastatin) is a cholesterol-lowering drug with unrivaled sales of $13 billion projected for 2006. Ranbaxy filed an Abbreviated New Drug Application (ANDA) and was sued for infringement of U.S. Patent Nos. 4,681,893 (the `893 patent) and 5,273,995 (the `995 patent). The `893 patent was set to expire May 30, 2006, but Pfizer was granted a patent term extension (based on FDA regulatory delay) extending the term to September 24, 2009. The asserted claims of the `893 patent recite a compound having structural formula I, depicted as a specific stereoisomer. Stereoisomers have the same molecular formula or atomic composition, but different spatial arrangements. Enantiomers are a pair of stereoisomers that are non-superimposable mirror images of each other and often have distinct physical properties. A racemate (or racemic mixture) is an equal mixture of two enantiomers.
The Federal Circuit rejected Ranbaxy’s argument that the district court erred in construing structural formula I "to embrace all trans-form isomers" rather than just racemates. Although only an R-trans enantiomer is depicted in the ’893 patent, the specification expressly indicated that there are four possible isomers of the compounds of structural formula I and limited the invention to the trans-form. The Court also disagreed with Ranbaxy’s argument that, because the specification only provided examples of reaction sequences that produce racemates, the claims should be limited to racemates. Citing its 2005 en banc decision in Phillips, the Court noted that restricting claim 1 on this basis would improperly import limitations from the specification into the claims. The Federal Circuit further agreed with the district court’s conclusion that statements made during prosecution of foreign counterparts, in response to patentability requirements unique to foreign laws, were irrelevant to claim construction as were statements made during prosecution of a later, unrelated U.S. patent. The Court also rejected the argument that the patent term extension was invalid because it was based on Ranbaxy’s rejected claim construction.
With regard to inequitable conduct, the Court concluded that statements made during prosecution of related patents were not material and that Pfizer’s failure to disclose these statements during prosecution of the `893 patent did not amount to a material omission.
However, with respect to the `995 patent, the Federal Circuit reversed the district court, which had declined to invalidate an asserted claim for failure to comply with the requirements of § 112, ¶ 4 that a dependent claim must further limit the subject matter of the claim from which it depends. In so doing, the Court noted that the dependent claim in question fell completely outside the scope of the claim from which it depended. The Court noted that applicants for U.S. patents must satisfy all statutory requirements prior to obtaining a patent, even those that are mostly procedural or technical.
Practice Note
This decision serves as a stark reminder that claims are the fence that ultimately protects patented technology and that technical failures in drafting a claim properly can leave a gaping hole in this fence.
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