Blog Big Molecule Watch April 20, 2022

Federal Circuit Reverses PTAB Decision in Amgen Biosimilar-Related IPR Appeal

On April 14, 2022, the U.S. Court of Appeals for the Federal Circuit reversed the PTAB’s determination in IPR2016-01542 that claims of Amgen’s U.S. Patent No. 8,952,138 are obvious.  The ’138 patent claims are directed to methods of refolding proteins by “contacting the protein with a refolding buffer comprising a redox component comprising a final thiol-pair ratio” of a specified range and a certain redox buffer strength to form a refold mixture.  Amgen appealed the Board’s construction of “final thiol-pair ratio” and its obviousness determination based on the construction.  Amgen argued that the plain language makes clear that the “redox component is a distinct volume from the refold buffer, and it is that redox component that comprised the claimed ‘final thiol-pair ratio.’”  The Federal Circuit agreed with Amgen, and found the PTAB’s construction “inconsistent with the plain language of claim 1 and the specification.”  Under the correct construction, the Federal Circuit found that claims 1-24 of the ’138 patent were not obvious over the prior art and reversed the PTAB’s decision.

Amgen had previously asserted the ’138 patent in BPCIA litigation against Apotex regarding Apotex’s filgrastim and pegfilgrastim biosimilars.  Amgen’s case was dismissed by the Southern District of Florida after the court concluded after a bench trial that Amgen had failed to prove that Apotex’s proposed product would infringe the ’138 patent claims.  That ruling was affirmed by the Federal Circuit on November 13, 2017.

During the BPCIA litigation, Apotex had challenged the ’138 patent claims in IPR2016-01542, leading to a final written decision by the PTAB finding the ’138 claims to be unpatentable as obvious over the prior art.  On March 24, 2020, the Federal Circuit vacated the PTAB’s final written decision and remanded in view of the court’s decision in Arthrex, which held that the appointment of Administrative Patent Judges to the PTAB violates the Appointments Clause of the Constitution.  On October 4, 2021, Amgen requested Director Review of the final written decision, which was denied on November 22, 2021.  The PTAB also ordered that the final written decision was the final decision of the agency, leading to the second appeal, in which the Federal Circuit reversed the PTAB’s determination that the ‘138 patent claims are obvious.  Apotex did not participate in the appeals, having already obtained a favorable judgment of non-infringement, and therefore the PTAB had picked up the reins to defend its decision.

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