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

Having found standing to sue, the court held that the nasal spray formulation of a known drug warranted patent protection.

April 26, 2017

Robins Kaplan GENERICally Speaking: A Hatch-Waxman Litigation Bulletin

Case Name:  Impax Labs., Inc. v. Lannett Holdings Inc., Nos. 14-0984, -999 (RGA), 2017 U.S. Dist. LEXIS 47244 (D. Del. Mar. 29, 2017) (Andrews, J.)

Drug Product and Patent(s)-in-Suit: Zomig® (zolmitriptan); U.S. Patents Nos. 6,750,237 (“the ’237 patent”) and 7,220,767 (“the ’767 patent”)

Nature of the Case and Issue(s) Presented:  The patents-in-suit claim a formulation of zolmitriptan that requires intranasal delivery.  Defendants challenged the validity of the patents arguing that the claims were anticipated or obvious because using zolmitriptan to treat migraines was well known.  Impax argued that the claims were valid because using zolmitriptan with a nasal delivery resulted in a less effective form of the active ingredient to be metabolized by the body.  Thus, it was counter-intuitive to use a nasal delivery with zolmitriptan. The district court found the claims valid.

Why Impax Prevailed:  Defendants first argued that Plaintiffs had not established standing to sue. The court disagreed. AstraZeneca was the assignee on the face of the patents. The patents-in-suit issued in 2004 and 2007, and they both ultimately related back to application 10/129, 773, filed on Nov. 28, 2000. The patents claimed priority from a 1999 United Kingdom patent application, No. 9928578.5. But while AstraZeneca AB was the assignee of both patents, and an assignment dated 2000 purported to give AstraZeneca AB all rights in the patents, the 2012 licensing agreement was between AstraZeneca UK and Impax. However, AstraZeneca AB consented to the license and AstraZeneca AB and AstraZeneca UK were commonly owned by AstraZeneca Plc.

The court found that it was possible that AstraZeneca UK had no ownership interest in the patents, in which case it should not be a plaintiff. Defendants, however, had not moved to dismiss AZUK, but only to dismiss the case in its entirety for lack of standing. Because there was a valid assignment of the patents to AstraZeneca AB, AstraZeneca AB had consented to an exclusive license to Impax, and there was no evidence that the patents-in-suit had been assigned outside of the three plaintiffs. The court then moved on to analyze Defendants’ invalidity arguments.

Defendants first argued that the asserted claims were anticipated by the Marquess and Chauveau references. Both asserted claims required: (i) zolmitriptan; (ii) in a nasal spray; (iii) at a certain pH. But the court found that Marquess did not disclose a pH and did not disclose zolmitriptan as used in the patents-in-suit. And while Chauveau discussed pH, those disclosures related to the pH of molecules that are not zolmitriptan.

The court found that the attribute of zolmitriptan of bypassing the liver and the limitations of first-pass metabolism (because it was administrated as a nasal spray) supported its non-obviousness in three ways. First, the state of the art taught away from putting zolmitriptan in a nasal spray because of its active metabolite. The court credited Plaintiffs’ expert’s testimony that it would be “absolutely counterintuitive to make a nasal spray when you have an active metabolite which is more potent ... than the drug itself ....” Second, because of zolmitriptan’s reliance on its active metabolite, the prior art failed to teach that zolmitriptan by itself would be effective. Third, a skilled artisan would not have had a motivation to combine zolmitriptan with a nasal spray. Defendants had not shown the motivation existed, and the prior art did not give a reason that it would. The court found no prima facie case of obviousness.

Next, the court analyzed Plaintiffs’ objective-indicia evidence comprising (i) licensing; (ii) commercial success; (iii) industry praise; (iv) long-felt need; and (v) unexpected results. With regard to licensing, Impax had paid AstraZeneca $130 million for an exclusive license to the Zomig franchise and agreed to varying royalty rates, including 40% on the nasal spray. With the court’s having found there was a nexus between the licensing of the nasal spray and the licensing payment, this secondary consideration weighed in favor of non-obviousness. Plaintiffs next presented evidence of commercial success in the form of revenue growth and market share. But those data were inconclusive. Thus, the data provided no probative evidence of commercial success. Plaintiffs offered evidence of industry praise in three forms. First, Plaintiffs’ expert testified Zomig nasal spray was and is his number one migraine treatment. Second, Plaintiffs proffered an industry newsletter touting that the nasal spray as a formulation that “answers pressing need in migraine.” Third, Plaintiffs proffered a marketing survey of 197 neurologists and pediatric neurologists. But the court found that this evidence had little probative force. Plaintiffs’ expert’s personal practice was not a stand-in for industry praise. The industry newsletter, while praising Zomig nasal spray, was unsigned. Therefore, attributing any weight to it would be speculative. Finally, the marketing survey was offered without context, as it did not focus on product performance. The court therefore found inadequate proof to support a finding of industry praise. The court made similar findings for the remaining secondary considerations.

While acknowledging that the question of obviousness in this case was “a close one,” the court found that Defendants had not met their clear and convincing evidence standard. It credited Plaintiffs’ experts over Defendants’ experts.

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