Regeneron Pharmaceuticals has filed a new patent infringement complaint against Amgen under the Biologics Price Competition and Innovation Act (BPCIA), alleging that Amgen's aflibercept biosimilar PAVBLU infringes U.S. Patent No. 12,331,099. The patent, which issued on June 17, 2025, covers claims directed to a stable liquid ophthalmic formulation containing a vascular endothelial growth factor (VEGF) antagonist that does not require a buffer.
Strategic Patent Enforcement Amid Commercial Launch
Amgen commercially launched PAVBLU in the United States in November 2024, following the Federal Circuit's denial of Regeneron's motion for an injunction pending appeal. The launch occurred after the U.S. District Court for the Northern District of West Virginia denied Regeneron's preliminary injunction motion in litigation involving a separate patent, U.S. Patent No. 11,084,865, which covers ophthalmic formulations with VEGF antagonists that include buffer components.
On March 14, 2025, the Federal Circuit affirmed the district court's decision regarding the earlier patent, clearing the path for Amgen's biosimilar to remain on the market while the new patent litigation proceeds.
Multidistrict Litigation Consolidation
Regeneron filed the new complaint in the U.S. District Court for the Central District of California but indicated it will petition the U.S. Judicial Panel on Multidistrict Litigation to transfer the case to the Northern District of West Virginia. The company seeks consolidation with MDL No. 1:24-md-3103-TSK, which currently includes multiple BPCIA actions against Amgen, Mylan/Biocon, Celltrion, Formycon, Samsung Bioepis, and Sandoz.
In the new complaint, Regeneron seeks judgment of patent infringement, damages, injunctive relief to halt further PAVBLU sales, and attorney's fees.
PTAB Strengthens Patent Position
The Patent Trial and Appeal Board recently denied institution of inter partes review petitions filed separately by Samsung Bioepis and Formycon challenging Regeneron's U.S. Patent No. 11,084,865. The PTAB panel exercised discretion under 35 U.S.C. § 314(a) without reaching the merits of the petitioners' unpatentability arguments.
The panel applied the Fintiv factors to balance system efficiency, fairness, and patent quality considerations. Factor 3, regarding investment in parallel proceedings, "weighs heavily in favor of discretionary denial," the panel noted, citing the district court's completion of "a two-week trial in the Mylan case and three other preliminary-injunction proceedings focused on validity of the '865 patent."
Delayed Filing Strategy Backfires
The PTAB panel criticized the petitioners for delayed filing, stating they "were aware of the particular claims being asserted against [them] as early as February 2024 and could have filed a Petition challenging them far earlier than [they] did." The panel concluded that while the lack of a trial date weighed against denial, "that single factor is solidly outweighed by the sum of the others," including factors reflecting substantial investment in parallel district court proceedings.
Ongoing Patent Landscape
Regeneron has successfully defended its aflibercept formulation patents in multiple proceedings. Following a nine-day bench trial, the Northern District of West Virginia found that Mylan infringed certain claims of the '865 patent and failed to prove invalidity. That judgment was later resolved through a joint stipulation agreement between the parties.
The Federal Circuit has affirmed preliminary injunctions against Celltrion, Samsung, and Formycon on the '865 patent, while denying similar relief against Amgen. A pending petition by Celltrion for inter partes review of the '865 patent (IPR2025-00456) was filed on January 15, 2025.
