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Amgen Inc. v. Coherus Biosciences Inc.

Arguments During Prosecution Lead to Estoppel Against DOE

Amgen Inc. v. Coherus Biosciences Inc., __ F.3d __, 2019 WL 3403371 (Fed. Cir. July 29, 2019) (Reyna, Hughes, STOLL) (D. Del.: Stark) (3 of 5 stars)

Fed Cir affirms dismissal for failure to state a claim in biosimilar case. Amgen’s patent related to methods of purifying therapeutically useful proteins via hydrophobic interaction chromatography (“HIC”), and was relevant to making Amgen’s Neulasta (pegfilgrastim) treatment. The district court correctly determined that the file history for Amgen’s patent barred DOE infringement claims against Coherus’s process for making its biosimilar because Amgen had clearly surrendered techniques other than those expressly claimed. The opinion describes how the prosecution history requires a finding of argument-based estoppel (surrendering claim scope through argument to the examiner), citing Conoco, 460 F.3d 1349 (Fed. Cir. 2006). Amgen had made three separate arguments to distinguish over the prior art, and the opinion describes how estoppel can attach to each, per PODS, 484 F.3d 1359 (Fed. Cir. 2007). It also rejects Amgen’s suggestion that argument-based estoppel might not attach because the relevant arguments did not appear in Amgen’s final response. “There is no requirement that argument-based estoppel apply only to arguments made in the most recent submission before allowance.” Op. at 11.

KEYWORDS: BIOSIMILARS; PROSECUTION HISTORY ESTOPPEL; CLAIM CONSTRUCTION