AstraZeneca AB v. Hanmi USA, Inc.

Case Name: AstraZeneca AB v. Hanmi USA, Inc., No. 2013-1490, 2013 U.S. App. LEXIS 25199 (Fed. Cir. Dec. 19, 2013) (Circuit Judges Dyk, Moore, and Taranto presiding; Opinion by Taranto) (Appeal from D.N.J., Pisano, J.) (Affirming construction of the term “alkaline salt” and judgment of non-infringement based on that construction.)

Drug Product and Patent(s)-in-Suit: Nexium^® (magnesium salt of esomeprazole); U.S. Pat. Nos. 5,714,504 (“the ’504 patent”) and 5,877,192 (“the ’192 patent”)

Nature of the Case and Issue(s) Presented:  The active ingredient in AstraZeneca’s Nexium® is the magnesium (Mg²⁺) salt of esomeprazole. Hanmi sought FDA approval for a product that contains the strontium (Sr²⁺) salt of esomeprazole. The district court construed the term “alkaline salt” in the ’504 patent and “pharmaceutically acceptable salt” in the ’192 patent. AstraZeneca argued that the terms should include any “basic” salt of esomeprazole suitable for a pharmaceutical formulation. Hanmi argued that the terms are limited to the disclosed “Na⁺, Mg²⁺, Li⁺, K⁺, Ca²⁺ or N⁺(R)₄ salts of the single enantiomers of omeprazole.” The district court agreed with Hanmi’s construction. After the district court denied AstraZeneca’s motion for reconsideration, the parties consented to entry of final judgment of non-infringement. After reviewing the specification and the prosecution history, the Federal Circuit affirmed the district court’s construction and the judgment of non-infringement based on that construction.

Why Hanmi Prevailed:  The Federal Circuit found that the specification contains a clear disclaimer of any salt except those using six enumerated cations. It found that AstraZeneca conveyed a clear and definite meaning that it was disclaiming other members of a class by conspicuously choosing only certain members of the class. While it is undisputed that the term “alkaline salt” on its face and outside the ’504 patent would not be limited to the enumerated cations, the Federal Circuit determined that the first sentence of the Detailed Description and the Abstract clearly confines the patent scope to the six cations. The Detailed Description declares that “[t]he present invention refers to the new Na⁺, Mg²⁺, Li⁺, K⁺, Ca²⁺ or N⁺(R)₄ salts of the single enantiomers of omeprazole, where R is an alkyl with 1-4 carbon atoms, i.e. Na⁺, Mg²⁺, Li⁺, K⁺, Ca²⁺ or N⁺(R)₄ salts of (+)-[omeprazole] and (-)-[omeprazole], where R is an alkyl with 1-4 carbon atoms.” The Federal Circuit found that this language defined the present invention as a particular set of “new” salts of enantiomers of omeprazole—salts with the six enumerated cations. This interpretation was supported by the Abstract which states “[t]he novel optically pure compounds Na⁺, Mg²⁺, Li⁺, K⁺, Ca²⁺ or N⁺(R)₄ salts of (+)-[omeprazole] or (-)-[omeprazole], in particular sodium and magnesium salt form thereof….” AstraZeneca attempted to overcome the disclaimer by asserting three arguments. First, relying on the word “exemplified,” AstraZeneca pointed to a single passage in the specification to show its intent to cover more than the six enumerated cations. The specification states “Alkaline salts of the single enan-tiomers of the invention are, as mentioned above, beside the sodium salts…and the magnesium salts…, exemplified by their salts with Li⁺, K⁺, Ca²⁺ or N⁺(R)₄, where R is an alkyl with 1-4 C-atoms.” The Federal Circuit rejected this argument, since the “exemplified” language applies only to four of the six cations and does not include any other language to suggest that the identified cations were merely exemplary. Second, AstraZeneca argued that the prosecution history overcomes the disclaimer by focusing on the term’s genus. During prosecution, AstraZeneca submitted clinical studies which supported “the full scope of the genus of alkaline salts disclosed….” The Federal Circuit was not persuaded since the prosecution history does not mention or include data for any salt beyond what is identified in the specification. Finally, AstraZeneca argued based on claim differentiation since 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.” Relying on precedent that the doctrine of claim differentiation does not override clear statements of scope in the specification, the Federal Circuit found that these differences in claim language could not overcome the unmistakable limitation set out in the written description.