Addressing the issue of obviousness, the US Court of Appeals for the Federal Circuit affirmed the district court's finding that a patent was invalid based on inherency because the claim limitation was necessarily present in the prior art. Hospira, Inc. v. Fresenius Kabi USA, LLC, Case Nos. 19-1329, -1367 (Fed. Cir. Jan. 9, 2020) (Lourie, J).
The patent at-issue is directed to premixed pharmaceutical compositions of dexmedetomidine that do not require reconstitution or dilution prior to administration and remains stable and active after prolonged storage. Hospira makes and sells dexmedetomidine products, including a ready-to-use product called Precedex Premix covered by the patent at-issue. Fresenius filed an Abbreviated New Drug Application (ANDA) seeking approval by the Food and Drug Administration (FDA) to market a generic ready-to-use dexmedetomidine product. Hospira brought suit alleging infringement under the Hatch-Waxman Act.
After a five-day bench trial and post-trial briefing, the district court held the asserted patent claim invalid because it would have been obvious over the prior art. The district court found that the 4µg/mL preferred embodiment was expressly taught by the prior art and the "about 2% limitation," which referred to the claim limitation that read "wherein the liquid pharmaceutical composition when stored in the glass container for at least five months exhibits no more than about 2% decrease in the concentration of dexmedetomidine" was inherent based on 20 tested samples that were either from Hospira's NDA or Fresenius' ANDA. The district court also found that a person of ordinary skill would have had a reasonable expectation of success in achieving the "about 2% limitation." Hospira appealed arguing that the district court incorrectly applied the inherency doctrine by considering the inherent properties of non-prior art embodiments and erroneously applied a lower "reasonable expectation of success" standard rather than the higher "necessarily present" standard to the inherency question.
The Federal Circuit affirmed. Turning first to the issue of the reliance on non-prior art embodiments, the Court agreed that the district court did not err in relying on data obtained after the priority date of the asserted patent in its inherency analysis. The Court explained that this "later evidence is not itself prior art; it only helps to elucidate what the prior art consisted of" and it was not legally incorrect for the district court to rely on non-prior art data from Hospira's NDA and Fresenius' ANDA as evidence of inherent stability of the 4µg/mL preferred embodiment.
Turning next to the issue of whether the district court applied the wrong standard to the inherency question, the Federal Circuit held that the only dispute was whether the district court's inherency analysis was correct and answered in the affirmative. The Court noted that the district court engaged in unnecessary analysis in evaluating whether a person of ordinary skill would have had a reasonable expectation of successfully achieving the about 2% limitation and thus, conflated the standards for inherency and reasonable expectation of success. But the Court found this was harmless error because "[i]f a property of a composition is in fact inherent, there is no question of a reasonable expectation of success in achieving it."
Finally, the Federal Circuit held that as a legal matter, the inclusion of an inherent, but undisclosed property of a composition [the about 2% limitation] did not render a claim to the composition non-obvious, because a patent can be invalid based on inherency when the patent itself makes clear that a limitation is "not an additional requirement imposed by the claims..., but rather a property necessarily present." Here, the Court found that the asserted claim did not recite any manufacturing limitations related to stability or an added component that enhanced stability—it simply recited a composition with a "wherein" clause that described the stability of that recited composition, a result that was inherent in the prior art.
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