Last week, the district court in Amgen v. Apotex (No. 18-61828) (S.D. Fla.) denied Apotex’s motion to dismiss Amgen’s complaint in a follow-on suit concerning Apotex’s pegfilgrastim and filgrastim biosimilar candidates.
By way of background, Amgen and Apotex have been involved in multiple patent lawsuits regarding Apotex’s pegfilgrastim and filgrastim biosimilars since August 2015. As we covered in an earlier post, in December 2018, Apotex filed a motion to dismiss Amgen’s complaint in a lawsuit concerning Apotex’s proposed biosimilar versions of Amgen’s Neupogen and Neulasta products. Amgen’s complaint in this second lawsuit alleged infringement of a manufacturing-process patent (U.S. Patent No. 9,856,287) that is related to the patent asserted in the first lawsuit (U.S. Patent No. 8,952,138). In the first lawsuit, the district court found that Apotex’s process did not infringe the ‘138 patent, and the Federal Circuit affirmed that decision in November 2017. The related ‘287 patent issued in January 2018, and Amgen filed the second lawsuit on that patent on August 7, 2018.
In its motion to dismiss, Apotex argued that Amgen’s infringement claims were barred under the doctrine of collateral estoppel—because Amgen is estopped from re-litigating claim construction issues that were already decided in the first case—and/or under the doctrine of prosecution history disclaimer.
The district court denied Apotex’s motion on both grounds, stating: “While Apotex may ultimately win this case as to one or both of these arguments, the Court finds that the instant motion is due to be denied at this stage of the litigation.”
First, the court found that it was “inappropriate to apply collateral estoppel at this stage of the proceedings to prohibit Amgen from arguing a different meaning” for claim terms that were construed in the prior case, because the claim language in the new patent is different. The court concluded that until it “conducts a Markman hearing and properly construes the claims of the 287 patent, the Court cannot determine whether there are material differences in the claim terms that were not previously litigated,” and thus declined to dismiss the complaint on collateral estoppel grounds.
The court also rejected Apotex’s motion to dismiss on grounds of prosecution history disclaimer, because it found that “the prosecution statements cited by Apotex…do not ‘evince a clear and unmistakable surrender of subject matter’ as the law requires, to permit the Court to apply prosecution history disclaimer at this early juncture,” though it noted that “[t]he Court may revisit these arguments at a later stage of the proceedings following claim construction and discovery.”