Sanofi & Regeneron Seek to Assert Inequitable Conduct Defense in Dupilumab Patent Litigation

As we previously reported, Immunex sued Sanofi and Regeneron earlier this year in the Central District of California alleging that the sale of Sanofi and Regeneron’s FDA-approved Dupixent® (dupilumab) product would infringe Immunex’s U.S. Patent 8,679,487.  Today, the defendants in the case filed a motion to file a first amended answer to assert a defense of inequitable conduct.

Most of the motion papers, including the proposed amended answer, have been filed under seal, but the publicly accessible papers summarize the defendants’ allegations as follows: “During the prosecution of the family of patents that led to the ‘487 Patent Immunex argued that the ‘competes’ limitation was the point of novelty and in response to invalidity arguments made by the examiner based on prior art mouse monoclonal antibodies to human IL-4R, Immunex responded that there was no evidence that any prior art antibodies compete with the 12B5 antibody an [sic] demanded such evidence be provided by the examiner.”  The motion papers state that Immunex “intend[s] to oppose Defendants’ motion for leave to amend on futility grounds.”

Stay tuned to Big Molecule Watch for further developments.