Sumitomo Dainippon Pharma Co. v. Emcure Pharms. Ltd.

Case Name: Sumitomo Dainippon Pharma Co. v. Emcure Pharms. Ltd., Fed. Cir. Nos. 2017-1798, 2017-1799, 2017-1800 (Fed. Cir. Apr. 16, 2018) (Circuit Judges Moore, Mayer, and Stoll presiding; Opinion by Stoll, J.) (Appeals from D.N.J., Chesler, J.)

Drug Product and Patent(s)-in-Suit: Latuda® (lurasidone); U.S. Patent No. 5,532,372 (“the ’372 patent”)

Nature of Case and Issue(s) Presented: Plaintiff owned the ’372 patent, which related generally to “novel imide compounds and their acid addition salts” that were useful as antipsychotic agents. The ’372 patent disclosed and claimed more than one billion compounds, some of which had stereo and optical isomers. Among those compounds was lurasidone, the (-)-enantiomer of a covered imide compound. After multiple defendants filed ANDAs with the FDA seeking approval to market generic versions of Latuda, Plaintiff sued alleging infringement of claim 14 of the ‘’372 patent. Claim 14 described a chiral molecule and both parties agreed that the specific three-dimensional structure depicted in that claim was lurasidone, the (-)-enantiomer.

At the district court, defendants sought to limit claim 14 to “a racemic mixture of two enantiomers of which the structural formula is representative.” The district court rejected defendants’ narrow construction, which would have excluded the specific enantiomer depicted in claim 14. Instead, the district court adopted plaintiff’s proposal to construe claim 14 as covering “lurasidone, lurasidone’s enantiomer, as well as mixtures of these enantiomers.” In light of this construction, defendants stipulated to infringement and appealed. The Federal Circuit affirmed.

Why Sumitomo Prevailed: The plain claim language and specification demonstrated that, at a minimum, claim 14 covered what it depicted: the (-)-enantiomer. The Federal Circuit found that this alone sufficed to resolve the parties’ dispute because defendants conceded that the district court’s judgment could be affirmed if the Federal Circuit were to conclude that claim 14 covered at least the (-)-enantiomer. Claim 14 recited a specific enantiomer and its acid-addition salts. Both parties agreed that the structure shown in the claim was the (-)-enantiomer; moreover, defendants did not dispute the fact that a person of ordinary skill looking at claim 14’s structure in a vacuum would have understood it to be one way of depicting the (-)-enantiomer. Of equal import was the lack of anything in the claim language limiting its scope to a “racemate” or “racemic mixture.” The specification confirmed the district court’s construction. Instead of suggesting that the (-)-enantiomer should be excluded, the specification described it as a preferred embodiment. Although its structure was not shown, Example 1(e) detailed the steps for obtaining Compound No. 105, the (-)-enantiomer, from Compound No. 101 and even provided data on Compound No. 105’s physical properties.

Moreover, defendants’ claim construction arguments conflicted with Federal Circuit precedent: they sought to import limitations from the specification into the claim. The specification also did not disclaim the (-)-enantiomer. Nothing in the ’372 patent’s specification disparaged a specific enantiomer, referred to a racemic mixture as forming the basis for the present invention, or described a racemic mixture as the basis for all of the ’372 patents embodiments.

Finally, defendants’ organic chemistry textbooks and expert testimony did not compel a different result. Here, the Federal Circuit found no error in the district court’s rejection of the extrinsic evidence presented by defendants as irrelevant or contradictory to plaintiff’s construction.