Federal Circuit dismisses Amgen’s Neulasta appeal
California-based Amgen is barred from succeeding on its patent infringement claim against Coherus Biosciences, according to the US Court of Appeals for the Federal Circuit.
In a precedential decision issued yesterday, July 29, the Federal Circuit held that, under the doctrine of prosecution history estoppel, Amgen couldn’t rely on an argument it had disavowed before the US Patent and Trademark Office (USPTO).
Amgen’s US patent 8,273,707, which claims methods of “purifying proteins using hydrophobic interaction chromatography”, was rejected twice by the USPTO in light of prior art, US patent number 5,231,178 (Holtz).
In response to the rejections, Amgen argued that its patent claimed a particular combination of salts, unlike the Holtz patent, and the examiner then allowed the claims.
In August 2016, Coherus filed an abbreviated Biologic License Application (aBLA) seeking Food and Drug Administration approval to market a biosimilar version of Amgen’s pegfilgrastim product Neulasta, a drug given to patients undergoing chemotherapy.
Amgen sued Coherus in May 2017, alleging infringement under the doctrine of equivalents because the salt combination used in Coherus’s process didn’t match any of the three expressly claimed salt combinations in the ‘707 patent.
Coherus asked the court to dismiss the allegations, arguing that there was “no plausible interpretation under which Coherus would infringe the patent-in-suit”.
The magistrate judge issued a report and recommendation, recommending that Coherus’s motion to dismiss be granted and noting that, during prosecution, Amgen had distinguished Holtz by arguing that Holtz did not disclose “one of the particular, recited combinations of salts”.
“Based on this, the magistrate judge determined that Amgen ‘clearly and unmistakably—and indeed, repeatedly—indicated to competitors that it surrendered processes using combinations of salts different from the ‘particular combinations of salts recited in the … claims’,” said the Federal Circuit yesterday.
The district court adopted the magistrate judge’s report and granted the motion, a decision Amgen appealed against.
Amgen argued that its statement regarding the particular combinations of salts “simply observes (correctly) as a factual matter that Holtz does not disclose using combinations of salts in the first instance”, so does not “clearly and unmistakably” surrender unclaimed salt pairs.
But the Federal Circuit sided with the district court, finding that Amgen had “clearly and unmistakably surrendered salt combinations other than the particular combinations recited in the claims” during prosecution.
Circuit Judge Kara Stoll, on behalf of the Federal Circuit, said: “Prosecution history estoppel thus bars Amgen from succeeding on its infringement claim under the doctrine of equivalents.”
Thomas Fitzpatrick, Coherus’ chief legal officer, said the company was pleased with the decision.
He added: “We are particularly pleased to continue our mission to successfully lower healthcare costs and expand patients’ access to life-saving drugs.”
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