United States: Prior Art May Teach Away From A Formulation Despite Reference To It

Deferring to the district courts findings of fact regarding a prior art reference "teaching away", the US Court of Appeals for the Federal Circuit upheld a decision finding patents directed toward intranasal formulations for treating migraines were non-obvious.  Impax Laboratories Inc. v. Lannett Holdings Inc., Case No. 17-2020 (Fed. Cir. 2018) (Lourie, J.)

AstraZeneca owns the two asserted patents relating to pharmaceutical formulations of zolmitriptan for intranasal administration.  Zolmitriptan belongs to a class of drugs known as triptans, which work as selective serotonin receptor agonists and are used to treat migraines and cluster headaches.  Impax is the exclusive licensee of the asserted patents. 

AstraZeneca also owns a New Drug Application (NDA) for Zomig (brand name for zolmitriptan) formulated as a nasal spray for treatment of migraines.  In June of 2014, Lannett notified AstraZeneca that it had filed an Abbreviated New Drug Application (ANDA) along with a paragraph IV certification stating that AstraZeneca's patents were invalid or unenforceable.  Impax filed suit.

At trial, Lannett stipulated to infringement, but argued that the asserted claims of the asserted patent were invalid under 35 U.S.C. §§102 & 103.  After a bench trial, the district court found that the asserted claims were not invalid, entering a judgment in favor of Impax and entering an injunction against Lannett to prevent its entry into the market. Lannett appealed.

The only issue on appeal is the district court's non-obviousness finding.  At trial Lannett had raised obviousness arguments based on "Marquess", "Chauveau" and "Stewart & Tepper". At the outset, the Federal Circuit determined that Lannett had waived any invalidity argument as to Marquess and Stewart & Tepper because Lannett alluded to these references teaching nasal formulations of zolmitriptan without making any particular invalidity arguments based on these references.

The Federal Circuit next analyzed the obviousness argument based on Chauveau—a patent which is generally directed to formulating an active ingredient for use in intranasal drug delivery.  The Chauveau patent offered a laundry list of potential ingredients including triptans, such as sumatriptan and zolmitriptan.  The district court, however, discounted this disclosure, explaining that these formulations were barely mentioned, that the reference as a whole was not about intranasal formulations of zolmitriptan, and that the reference taught away from using an intranasal formulation to deliver zolmitriptan. As taught in the Chauveau patent, intranasal formulations are generally advantageous because they prevent the rapid break down of the drug that oral formulations experience in the digestive system.  However, zolmitriptan is known to be active by way of its metabolite (i.e. its breakdown product).  This is a unique property to zolmitriptan and most triptans do not rely on their metabolite for efficacy. 

Ultimately, the district court called the case a close one, finding that while zolmitriptan was expressly listed as a potential active ingredient in the Chauveau patent, the passing reference was not enough. The district court found that the fact that zolmitriptan had a known powerful metabolite, the creation of which would be delayed and diminished by nasal administration, would point a skilled artisan away from including zolmitriptan in a nasal spray.  The Federal Circuit agreed that this case was close, and deferred to the district court in its fact findings, including what Chauveau discloses and the state of the prior art as a whole.

Lannett also argued that the district court erred in finding that a 2012 agreement which encompassed the entire Zomig franchise, including matters unrelated to the asserted patents, supported its conclusion of non-obviousness. Based on the timing of the 2012 agreement as it related to the various formulation patents and the sales data presented to the district court, the Federal Circuit found that a portion of the consideration exchanged was based on expected profits from the Zomig spray. These conclusions were also supported by corroborating evidence in Impax's press release and the Federal Circuit saw no error in the district court's use of the 2012 agreement between Impax and AstraZeneca as an objective indicia of non-obviousness. 

Practice Note:  Overturning a finding of obviousness at the Federal Circuit is an uphill battle.  The Federal Circuit has repeatedly deferred to the district court for "close cases".  This is a fact driven analysis and appellants should rely heavily on the trial record and avoid conclusory obviousness arguments without evidentiary support.   

Prior Art May Teach Away From A Formulation Despite Reference To It

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