United States: A Given Claim Term Can Have Different Meanings In Different Contexts In The Patent

In Aventis Pharmaceuticals, Inc. v. Amino Chemicals Ltd., Nos. 11-1335, -1336 (Fed. Cir. May 20, 2013), the Federal Circuit reversed and remanded the district court's entry of a stipulated judgment of noninfringement, concluding that the district court's Markman opinion misinterpreted claim terms of U.S. Patent No. 5,750,703 ("the '703 patent").

The '703 patent is owned by Albany Molecular Research, Inc. ("AMRI") and directed to processes for making piperidine derivatives used in antihistamine products.  Sanofi-Aventis U.S., the exclusive licensee of the '703 patent, uses the patented process to produce fexofenadine for its Allegra® and Allegra-D® 24 Hour products.  Amino Chemicals Ltd., Dipharma Francis, Sr.L., and Dipharma Spa (collectively "Appellees") are generic drug manufacturers for Mylan Pharmaceutical Inc. ("Mylan") and Teva Pharmaceuticals USA, Inc. ("Teva").  Several generic drug companies, including Mylan and Teva, filed ANDAs with the FDA seeking approval to market generic fexofenadine antihistamine products, and Aventis Pharmaceuticals, Inc. and AMRI (collectively "Appellants") sued them for patent infringement.  In a Markman hearing, the district court construed the claim term "substantially pure" to mean "at least 98% purity with respect to all impurities."  Slip op. at 18-19 (citation omitted).  In light of this construction, Appellants stipulated that they could no longer prove infringement, and the district court entered final judgment in favor of Appellees.  Appellants appealed the disputed claim construction.

On appeal, the Federal Circuit first held that the district court erred in concluding that the term "substantially pure" had only one construction throughout the '703 patent, and that a proper construction required different interpretations of "substantially pure" when applied to the intermediate and the end product.  The Court reasoned that while the specification used "substantially pure" for both the intermediate and the end product, the claims-at-issue used the term only to refer to the intermediate.  The Court noted that a person of ordinary skill in the art would recognize that an intermediate of a claimed chemical reaction would not be required to have the same purity as the end product, and that the improvement of the patented process over the prior art process was that the patented process could provide an end product of higher regioisomeric purity requiring less extensive purification.  The Court stated that the district court's "one-size-fits-all" construction incorrectly construed "substantially pure" separate from the next word, "regioisomer."  Id. at 23.

"The lack of any 'substantially pure' limitation on the piperidine derivative end products in claims 1, 6, and 7 obviates any explicit requirement to apply a construction of 'substantially pure' that is consistent for both the CPK intermediate and the piperidine derivative end product."  Slip op. at 22.

Regarding construction of the term "substantially pure regioisomer," the Federal Circuit disagreed with the district court's reliance on statements made in an interference proceeding involving a related patent.  The Court explained that the focus of that interference was interpreting the claims in reference to the end product, and that there was no justification for applying the definition to the term "substantially pure regioisomer" in the '703 patent.  The Court also disagreed with the district court's conclusion that "substantially pure" applied to all impurities, not just regioisomeric impurities, stating that the flawed analysis did not consider the appropriate frame of reference for claim construction, namely, the improvement of the patented process over the prior art process.  The Court further reasoned that the '703 patent contemplated the need for further purification steps after the claimed reactions, and that the general purity of other reaction components was largely irrelevant at the intermediate stage.

The Federal Circuit stated that "[w]ith no explicit construction of the term 'substantially pure' in the claims, specification, or prosecution history, we apply the 'ordinary and customary' definition to the claim term."  Id. at 27.  In doing so, the Court adopted Appellants' proposed construction of "substantially pure regioisomer of the following formula" as "largely but not wholly the para regioisomer of the intermediate of the structure shown, as compared to the meta isomer."  Id. at 29.  The Court reasoned that the construction was previously applied, with approval by the Court, that "largely but not wholly" was consistent with a flexible approach to regioisomeric purity for an intermediate, was faithful to the specification's silence regarding numerical precision, and, most importantly, was not arbitrarily tied to the FDA standard for pharmaceutical-grade end products.  Accordingly, the Court reversed and remanded the district court's ruling of no infringement.

Judge Bryson dissented, stating that he would uphold the district court's construction of "substantially pure" as "at least 98% purity with respect to all impurities."  Bryson Dissent at 1.  Judge Bryson opined that there was no basis for ignoring the intrinsic record, which did not distinguish between using the term "substantially pure" for the intermediate and using it for the end product, or for ignoring the presumption under general claim construction principles that "substantially pure" was a concrete term that had a consistent meaning throughout the '703 patent.

Judges: Newman, Bryson (dissenting), Reyna (author)
[Appealed from D.N.J., Chief Judge Brown]

This article previously appeared in Last Month at the Federal Circuit, June 2013

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