Pfizer Moves to Dismiss Amgen’s Suit Over Proposed Neulasta Biosimilar

As we previously reported, on February 11, 2020, Amgen sued Pfizer and its affiliate Hospira, alleging that their proposed biosimilar of Amgen’s NEULASTA (pegfilgrastim) would infringe U.S. Patent No. 8,273,707 (“the ’707 patent”).  The ’707 patent is directed at methods of protein purification.

Last week, Pfizer filed a motion to dismiss Amgen’s complaint under Federal Rule of Civil Procedure 12(b)(6) for failure to state a claim.  In the motion, Pfizer argues that during prosecution of the ’707 patent, Amgen distinguished a prior art patent on the ground that it used a salt concentration below the claimed range for protein purification, and therefore Amgen surrendered from the scope of the asserted claims subject matter—the lower salt concentration—covering Pfizer’s manufacturing process.  Therefore, according to Pfizer, Pfizer’s process does not infringe the patent as a matter of law.  In its argument, Pfizer relies on the Federal Circuit’s decision in Amgen v. Coherus, that affirmed the dismissal of Amgen’s claim that Coherus’ NEULASTA biosimilar infringes the ’707 patent based on prosecution history estoppel.  Pfizer argues that although the Coherus decision applied prosecution history estoppel “in connection with a different claim limitation” than the limitation on which Pfizer bases its non-infringement position, the reasoning in the Coherus case also applies to Amgen’s asserted claims.