Impax Labs Inc. v. Lannett Holdings Inc., LLC

Having found no teaching away and nexus between secondary considerations of non-obviousness and the asserted claims, the Federal Circuit affirmed the validity of the patents-in-suit.

June 28, 2018

GENERICally Speaking: A Hatch Waxman Litigation Bulletin

Case Name: Impax Labs Inc. v. Lannett Holdings Inc., LLC, No. 2017-2020 (Fed. Cir. June 28, 2018) (Circuit Judges Lourie, Dyk, and Taranto presiding; Opinion by Lourie, J.) (Appeal from D. Del., Andrews, J.)

Drug Product and Patent(s)-in-Suit: Zomig® (zolmitriptan nasal spray); U.S. Patents Nos. 6,760,237 (“the ’237 patent”) and 7,220,676 (“the ’767 patent”)

Nature of Case and Issue(s) Presented: The patents-in-suit are directed to pharmaceutical nasal formulations and aqueous solutions of zolmitriptan, which is used for the treatment of migraines. Following a bench trial, the district court noted that the “question of obviousness is a close one,” but ultimately determined that Lannett failed to meet its burden of proving invalidity by clear and convincing evidence.

On appeal, Lannett argued that the district court erred by: (i) concluding that the prior art taught away from nasal formulations of zolmitriptan; and (ii) finding that a 2012 agreement between Impax and AstraZeneca, which encompassed the entire Zomig franchise—including matters unrelated to the patents-in-suit—supported its conclusion of non-obviousness. The Federal Circuit disagreed.

Why Plaintiffs Prevailed: Lannett argued that the prior art, in particular the Chauveau reference, expressly disclosed nasal formulations of zolmitriptan. Chauveau described formulations of an active ingredient for oromucosal administration, and its teachings applied to formulations for buccal, nasal, or pharyngeal administration. With regard to active agents, Chauveau taught the use of triptans, such as sumatriptan or zolmitriptan. The Federal Circuit noted, however, that zolmitriptan was mentioned only once in Chauveau, with no further mention in an example or claim. Moreover, Impax’s expert opined that zolmitriptan has a “unique attribute”—unlike sumatriptan—in that its “first-pass metabolism results in an active metabolite … which is two to eight times more powerful than zolmitriptan itself.” The Federal Circuit further noted that a skilled artisan would have expected delayed or lower therapeutic effectiveness from zolmitriptan if administered nasally because it would have been “absolutely counterintuitive to make a nasal spray when you have an active metabolite which is more potent … than the drug itself.” As a result, the Federal Circuit explained that a skilled artisan would have been dissuaded from making nasal formulations of zolmitriptan.

Lannett also argued that the 2012 license agreement between Impax and AstraZeneca did not support any secondary indicia of non-obviousness. In particular, Lannett argued that the $130 million agreement lacked nexus to the patents-in-suit. The Federal Circuit noted that the patents covering the oral formulations of zolmitriptan expired just over a year after the effective date of the 2012 agreement, but explained that the patents covering the nasal formulation of zolmitriptan—the ’237 and ’767 patents—were not set to expire until 2021. Based on this timing, the Federal Circuit noted that at least a portion of the $130 million had to be based on expected profits from Zomig nasal spray, the commercial embodiment of the patents-in-suit. 


Oren D. Langer


Managing Partner, New York Office
Member of Executive Board

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