In a non-precedential decision addressing the weight given to a patentee’s statements concerning “the present invention,” the U.S. Court of Appeals for the Federal Circuit affirmed the district Court’s construction, finding that a genus is limited to the specific species defined by the specification as “the present invention.”  AstraZeneca AB v. Hanmi USA Inc., Case No. 13-1490 (Fed. Cir., Dec. 19, 2013) (Taranto, J.).

AstraZeneca brought suit against Hanmi, alleging a pharmaceutical drug Hanmi proposed to market in the U.S. infringed AstraZeneca’s two patents-in-suit.  The patents-in-suit both relate to an omeprazole enantiomer drug used to treat acid reflux, which relates to AstraZeneca’s pharmaceutical drug popularly known as Nexium®.  AstraZeneca’s Nexium has an active ingredient of the magnesium (Mg2+) salt of esomeprazole.    In December 2010, Hanmi filed an application with the U.S. Food and Drug Administration (FDA) under 21 U.S.C. § 355(b)(2) seeking approval to sell a product that contains the strontium (Sr2+) salt of esomeprazole.  The two patents AstraZeneca asserted against Hanmi include the claim terms “alkaline salt” and “pharmaceutically acceptable salt.”

The district court, agreeing with Hanmi’s proposed construction, construed the claim terms “alkaline salt” and “pharmaceutically acceptable salt” as limited to the “Na+, Mg2+, Li+, K+, Ca2+ or N+(R)4 salts of the single enantiomers of omeprazole.”  The district court concluded that the patents-in-suit’s written description defined the invention as limited to the six disclosed salts.  AstraZeneca appealed.

The Federal Circuit affirmed the district court’s ruling, holding that “the written description, by clear disclaimer, limits the claim scope to” the Na+, Mg2+, Li+, K+, Ca2+ or N+(R)4 salts of the single enantiomers of omeprazole.  The Court held that “[b]y conspicuously choosing only certain members of the class, and using the language it did, AstraZeneca conveyed a clear and definitive meaning that it was disclaiming other members of the class” and the doctrine of claim differentiation could not overcome this express language in the specification.

The Court noted specific portions of the written description limited the claim term “alkaline salt.”  Specifically, the Court cited the first sentence of the Detailed Description, which states “[t]he present invention refers to the new Na+, Mg2+, Li+, K+, Ca2+ or N+(R)4 salts of the single enantiomers of omeprazole.”  The Court held that these statements “clearly confine the invention to the six identified cations, disclaiming anything else.”  The Court noted that nothing in the written description or prosecution history expanded the scope of “alkaline salt” to include more than just these six salts.  The Court, citing The Toro Co., noted “the doctrine of claim differentiation does not . . . override clear statements of scope in the specification.”  The Court went on to note “[h]ere, 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.”

* Patrick J. Stafford was on Hanmi’s appeal brief.