AstraZeneca’s Zomig patents upheld in precedential ruling
The US Court of Appeals for the Federal Circuit has ruled that a passing mention in the prior art of a formulation that references the claimed ingredient and administration may not be enough to invalidate a patent claim.
Circuit Judge Alan Lourie delivered the precedential ruling on Thursday, June 28.
AstraZeneca owns US patent numbers 6,760,237 and 7,220,767, which cover pharmaceutical formulations containing zolmitriptan and are suitable for intranasal administration.
In 2012, AstraZeneca licensed the exclusive US commercial rights to Zomig (zolmitriptan) nasal spray to Impax Laboratories. The spray is used to treat migraines.
AstraZeneca and Impax filed a patent infringement suit against generic manufacturer Lannett in 2014, claiming that Lannett had infringed the Zomig patents in its filing of an Abbreviated New Drug Application with the Food and Drug Administration (FDA).
In response, Lannett argued that AstraZeneca’s patents were invalid.
Lannett filed an inter partes review (IPR) at the Patent Trial and Appeal Board (PTAB) in 2015. It argued that the asserted claims were invalid as obvious due to a prior reference which suggested that a formulation featuring zolmitriptan may be administered intra-nasally to treat migraines.
However, as the generics company filed its petition one day too late, the PTAB rejected it. Under US law, a party has to file an IPR petition within one year of being sued. Lannett had until July 27, 2015 to file the IPR, but did so on July 28.
In March 2017, the district court also rejected Lannett’s argument and upheld the validity of the Zomig patents. It said that if the FDA accepted Lannett’s application, the resulting product will infringe AstraZeneca’s patents.
“The prior art at the time failed to teach that zolmitriptan by itself, as contrasted with its metabolite, would have been effective,” the court said, adding that a skilled artisan would not have had a reasonable expectation of generating successful nasal formulations of zolmitriptan.
On appeal, Lannett argued that the district court had erred in its conclusion that the patent claims would not have been obvious.
The primary issue before the Federal Circuit was whether it would have been obvious to make zolmitriptan into a nasal spray.
Upholding the district court’s decision, Lourie said the ruling was supported by “underlying factual findings” which are not erroneous. Ultimately, Lannett failed to show a “strong case of obviousness”, Lourie added.
He explained that in an obviousness analysis, prior art should be viewed as a whole and that, when viewed this way, the prior art in this case “is not about intranasal formulations of zolmitriptan, which is barely mentioned”.
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