Richards Layton & Finger

Magistrate Judge Burke Recommends Granting Motion to Dismiss with Prejudice

March 6, 2018

In Amgen Inc. v. Coherus Biosciences Inc., No. 17-546-LPS-CJB (D. Del. Dec. 7, 2017), Magistrate Judge Burke recommended that the Court grant with prejudice Coherus Biosciences Inc.’s motion to dismiss for failure to state a claim. The plaintiff, Amgen Inc., had accused Coherus’ manufacturing process of infringing the asserted patent, all the claims of which included a limitation requiring one of three pairs of salts.

Coherus moved to dismiss on the basis that its manufacturing process did not satisfy at least this salt-pair limitation. According to the Court, there was no dispute that Coherus’ manufacturing process did not literally practice this limitation; instead, the complaint alleged that the accused process included the equivalent of the salt-pair limitation. Judge Burke deemed this allegation to be a legal conclusion lacking pleadings of fact that would render it plausible, recommending dismissal on this basis.

Coherus further argued that Amgen should not be granted leave to amend, because prosecution history estoppel barred Amgen from asserting the doctrine of equivalents for the salt-pair limitation. Reviewing the prosecution history, Judge Burke concluded that Amgen had distinguished the invention of the asserted patent over a prior art manufacturing process requiring the use of salts, since the prior art did not recite the particular combination of salts claimed in the asserted patent. Judge Burke found that this distinction was not merely clarifying, did not leave room for the assertion of other equivalents, and that nothing in the briefing suggested that claim construction would alter the Court’s conclusion. For these reasons, Judge Burke recommended that the complaint be dismissed with prejudice.

Key Point: Judge Burke found that it was appropriate to resolve the defendant’s prosecution history estoppel defense on a motion to dismiss when, according to the Court, the briefing did not explain how claim construction or discovery could affect the estoppel inquiry.