Forest Labs., Inc. v. Teva Pharms. USA, Inc.

Case Name:  Forest Labs., Inc. v. Teva Pharms. USA, Inc., No. 16-2550, -2553, 2017 U.S. Fed. Appx. LEXIS 24877 (Fed. Cir. Dec. 11, 2017) (Circuit Judges Lourie, Reyna, Taranto presiding; Opinion by Taranto, J.; Concurrence by Lourie, J.) (Appeal from D. Del., Stark, C.J.) 

Drug Product and Patents-in-Suit: Nameda XR® (memantine hydrochloride); U.S. Patents Nos. 8,168,209 (“the ’209 patent”), 8,173,708 (“the ’708 patent”), 8,283,379 (“the ’379 patent”), 8,329,752 (“the ’752 patent”), 8,362,085 (“the ’085 patent”), and 8,598,233 (“the ’233 patent”)

Nature of the Case and Issue(s) Presented:  When the parties addressed issues of claim construction, they disputed the construction of a term appearing, with slight variations, in the claims at issue. That term stated: “change in memantine concentration as a function of time (dC/dT) that is less than 50% that of an immediate release dosage form comprising the same dose of memantine as the composition.” Forest proposed that the language either be left unconstrued or be construed to mean a “change in plasma memantine concentration of the extended [sustained] release dosage form as a function of time (dC/dT) that is less than 50% that of an immediate release dosage form comprising the same dose of memantine as the extended [sustained] release dosage form.” Teva contended that the claim term was indefinite; it required the comparison of a concentration profile of an immediate-release formulation and a concentration profile of an extended-release formulation, as measured in human pharmacokinetic studies, but the patents were silent about how to conduct the studies to obtain those concentration profiles, and differences in study design led to variable results in the claim-required comparison.

The district court construed the claim to require that the concentration profile of the extended-release formulation and the concentration profile of the immediate-release formulation be measured in human pharmacokinetic studies, and found that the intrinsic evidence did not disclose a specific human-study design or provide guidance as to how to design a human study. The district court also found that the extrinsic evidence of how a person of skill in the art would understand the language at issue showed that measurements from human [pharmacokinetic] studies vary widely in terms of the concentration profiles they generate for any particular memantine formulation. The court entered a final judgment of invalidity based on indefiniteness, and Forest appealed. The Federal Circuit affirmed.

Why Teva Prevailed:  The Federal Circuit first addressed the issue of claim construction, and then the issue of whether the correct claim construction were indefinite. Forest argued that the district court erred by construing the claim to require  both of the concentration profiles being compared (extended v. immediate release) be derived from measurements in human pharmacokinetic studies. But the specification described Figures 1A and 2D as showing concentration profiles of a 20 mg memantine immediate-release formulation and a 20 mg memantine extended-release formulation. In addition, the figures and the accompanying descriptions supplied the same amount of detail for the immediate-release profile as for the extended-release profile. The Federal Circuit also reasoned that the prosecution history provided no support for Forest’s proposed construction. The inventor declaration submitted during prosecution described the results of a human pharmacokinetic study from which both immediate-release and extended-release profiles were derived.

Next, the Federal Circuit found that the district court’s indefiniteness ruling was supported by precedents that held claims indefinite in particular circumstances where the claims required measured quantities (absolute or relative), different techniques for such measurements were known in the art and some produced infringing results and others not. In such cases, the intrinsic evidence did not adequately specify the technique or techniques to use, and extrinsic evidence did not show that a relevant skilled artisan would know what technique or techniques to use.

Judge Lourie’s concurring opinion is in agreement with the outcome but for a different reason. The asserted claims attempt to encompass an extended-release formulation of memantine, but do so without including any materials that cause the extended release. “Claiming a result without reciting what materials produce that result is the epitome of an indefinite claim. Such a claim fails to delineate with any reasonable certainty the requirements of the formulation.”