Alerts11.5.25
Federal Circuit Reaffirms 'By Another' Standard Under Pre-AIA Law in Patent Dispute Over Merck Serono’s MS Drug Highlights
Highlights
- On Oct. 30, 2025, the U.S. Court of Appeals for the Federal Circuit issued a precedential decision in Merck Serono S.A. v. Hopewell Pharma Ventures, Inc., clarifying how “by another” prior art determinations should be made under pre-America Invents Act (AIA) patent law.
- The AIA was a major patent reform law enacted in 2011 that made significant changes to U.S. patent law, most notably by switching from a "first to invent" system to a "first inventor to file" system.
- The Court reaffirmed that for a reference to be excluded as prior art, the inventive entity must be exactly the same — a simple overlap of inventors is not enough.
The case involved a dispute over Merck’s patents on oral dosing regimens of cladribine for treating multiple sclerosis. Hopewell Pharma challenged the validity of these patents in inter partes review, arguing that prior art references — including a patent application by Bodor and a publication by Stelmasiak — rendered Merck’s claims obvious. Merck contended that these references should not qualify as prior art under pre-AIA law because they were created by Merck inventors or their collaborators, not “by another party.”
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