Amgen Fires Back With Counterclaims In Aflibercept BPCIA Litigation

As we previously reported, on June 17, 2025, Regeneron filed a complaint against Amgen under the BPCIA, alleging that Amgen's aflibercept biosimilar, PAVBLU, infringes U.S. Patent No. 12,331,099 ("the '099 patent"). The '099 patent issued on June 17, 2025, almost eight months after Amgen announced the launch of PAVBLU on October 30, 2024. Last week, on September 12, Amgen responded to Regeneron's complaint, firing back with fourteen affirmative defenses, including inequitable conduct and patent misuse, and counterclaims for declaratory judgments of non-infringement, invalidity, and unenforceability due to prosecution laches, inequitable conduct, and patent misuse, as well as Sherman Act antitrust "Walker Process" fraud claims and a counterclaim of unfair competition under California law.