• Jul 29 2019
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  • Category: CAFC Updates

Coherus filed an abbreviated Biologic License Application (“aBLA”) seeking FDA approval to market a biosimilar version of Amgen’s pegfilgrastim product Neulasta, a recombinant therapeutic protein that stimulates the production of neutrophils, a type of white blood cell. Amgen sued Coherus based on Coherus’s aBLA, alleging infringement under the doctrine of equivalents (rather than literal infringement) because the salt combination used in Coherus’s process did not match any of the three expressly claimed salt combinations in the asserted method patent. The district court dismissed Amgen’s complaint for failure to state a claim and Amgen appealed.  The CFAC agrees with the district court, holding that argument-based prosecution history estoppel applies here because Amgen clearly and unmistakably surrendered unclaimed salt combinations during prosecution. While Amgen did assert multiple reasons for why Holtz is distinguishable, estoppel can attach to each argument, so prosecution history estoppel applies to the “particular combinations” ground regardless of the other two arguments Amgen made. In addition, there is no requirement that argument-based estoppel apply only to arguments made in the most recent submission before allowance, but rather clear assertions made during prosecution in support of patentability, whether or not actually required to secure allowance of the claim, may also create an estoppel. Accordingly, the district court did not err in determining that prosecution history estoppel bars Amgen from succeeding on its infringement claim under the doctrine of equivalents. Accordingly, the CAFC affirms the district court’s order dismissing Amgen’s complaint for failure to state a claim.

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