Thursday, December 19, 2013

AstraZeneca loses to Hanmi on omeprazole case

The case AstraZeneca v. Hanmi presents a written description issue:

This appeal presents a single issue: whether the written description limits “alkaline salt” in the ’504 patent to certain specifically named salts. We hold that it does. The written description describes the invention clearly and narrowly as including only those salts, and Astra- Zeneca points to nothing in the intrinsic record that is sufficient to overcome that disclaimer.

Of background

AstraZeneca discovered that certain salts of an omeprazole enantiomer, as opposed to the racemate, have “improved pharmacokinetic and metabolic properties which will give an improved therapeutic profile such as a lower degree of interindividual variation.” ’504 patent, col. 1, lines 51-54. Its original application for the ’504 patent, filed in 1995 as a continuation-in-part of a 1994 application, described and claimed particular salts, de- fined by six identified cations: Na+, Mg2+, Li+, K+, Ca2+, or N+(R)4, where R is an alkyl with one to four carbons. Id. col. 1, line 1, to col. 6, line 35; J.A. 82-85. (The last formu- la denotes a class of ammonium cations, but for present purposes we may refer to it with the singular “cation”— making six cations in all.)
During prosecution, AstraZeneca conducted experi- ments that led it to conclude that one of the two enantio- mers gave particularly good results. J.A. 312-25. The preferred enantiomer is known as “(-)-omeprazole” or “(S) omeprazole,” sometimes written as “esomeprazole.”

The new claims, now at issue, are all limited to pharmaceutical compounds that contain certain esomeprazole salts as an active ingredient; but the independent claims no longer express- ly refer to the originally identified six cations, instead claiming an “alkaline salt” or “pharmaceutically accepta- ble salt.” See ’504 patent, col. 14, lines 5-49; ’192 patent, col. 7, line 17, to col. 8, line 54.

AstraZeneca argued that both terms have the same broad meaning: any “basic” salt of esomeprazole that is suitable for use in a pharmaceutical formulation. Hanmi argued that both terms are limited to the disclosed “Na+, Mg2+, Li+, K+, Ca2+ or N+(R)4 salts of the single enantiomers of omeprazole.” ’504 patent, col. 2, lines 42-44.


And because the court held that the ’192 patent incorporates the ’504 patent’s disclosure, it construed “pharmaceutical- ly acceptable salt” the same way.

An argument based on claim differentiation failed:

Finally, AstraZeneca presses an argument based on claim differentiation, noting that each independent claim reciting an “alkaline salt” has a dependent claim that differs only by the addition of “wherein the alkaline salt is a Na+, Mg2+, Li+, K+, Ca2+ or N+(R)4 salt.” See ’504 patent, col. 14, lines 14-15; id., col. 14, lines 48-49. But “the doctrine of claim differentiation does not ... override clear statements of scope in the specification.” The Toro Co. v. White Consol. Indus., Inc., 199 F.3d 1295, 1302 (Fed. Cir. 1999). Here, what otherwise might be an inference from differences in claim language cannot override the unmistakable limitation of “alkaline salt” set out in the written description.

See also
When the taste of salts is bitter - AstraZeneca loses appeal in Nexium case


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