Aventis Pharmaceuticals, Inc. et al. v. Amino Chemicals Ltd., et al.

Docket No. 2011-1335, -1336

May 20, 2013

Brief summary: The term “substantially pure” was determined to have different meanings when used in the context of chemical intermediates and the end product of the claimed process.

Summary: This case relates to processes for making Aventis’ antihistamine Allegra® and the DC decision following a Markman hearing. The process of the disputed patent (US 5,750,703) improved the prior art by using different intermediates to more readily separate out the final piperidine derivative end product, which is biologically active (unlike the product of prior art processes). The disputed claim terms are “substantially pure”, “providing” (“providing a substantially pure regioisomer”), and “converting” (“converting a substantially pure regioisomer”). The term “substantially pure” is not defined by the ‘703 specification. The DC concluded from the prosecution history that “the inventor understood the term ‘substantially pure’ to mean 98% purity and that the inventor clearly and unambiguously disavowed any other claim scope” and that that definition applied “to chemical impurities of any kind present in the product, not just regioisomeric impurity” (e.g., would also describe intermediate impurity). The FC opinion noted that while “the written description and other parts of the specification…may shed contextual light on the plain and ordinary meaning” of claim terms, “they cannot be used to narrow a claim term to deviate from the plain and ordinary meaning unless the inventor acted as his own lexicographer or intentionally disclaimed or disavowed claim scope” (citing, e.g., Markman (US 1996) and Phillips (FC 2005)). In addition, it was pointed out that while the prosecution history may be less useful, “it still provides evidence of how the inventor intended the term to be construed” (citing Lemelson, FC 1992 and Ormco, FC 2007). In addition, the same claim terms may have different constructions in different claims depending on the context (Microprocessor, FC 2008 (“particularly if it would lead to a ‘nonsensical reading'”)). In reversing the DC decision with respect to “substantially pure” intermediates, the FC determined that “a person of ordinary skill in the art would recognize that an intermediate of the claimed chemical reaction would not be required to have the same purity of the end product” and the improvement was not related to the purity of the intermediate but of the end product. Thus, it concluded that “[r]eading ‘substantially pure’ to require a consistent construction for the…intermediate and [the]…end product ignores the distinct context in which these terms are used.” The panel also concluded that “substantially pure, when construed in light of a person of ordinary skill in the art and in view of the claimed improvements over the prior art, only applies regioisomeric impurities, not all impurities” (e.g., not including “solvents, catalysts and other compounds”). The dissent argued that there was no basis in the record for these conclusions (e.g., “[i]f the patentee wanted ‘substantially pure’ to have different meanings when applied to different elements, it needed to explicitly ‘unlink’ them”).

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