Federal Circuit affirms ruling on Regeneron inequitable conduct

The US Court of Appeals for the Federal Circuit has affirmed a ruling of a lower court that found a patent owned by Regeneron unenforceable because of the biotech company’s inequitable conduct.

Yesterday, July 27, the Federal Circuit held in a 2-1 opinion that US patent number 8,502,018 (“Methods of modifying eukaryotic cells”) was unenforceable.

The patent relates to “using large DNA vectors to target and modify endogenous genes and chromosomal loci in eukaryotic cells”.

Regeneron had sued clinical-stage immuno-oncology company Merus in March 2014 at the US District Court for the Southern District of New York over infringement of the patent.

Merus asserted a counterclaim of unenforceability due to Regeneron’s inequitable conduct.

“It argued that Regeneron’s patent prosecutors withheld four references from the US Patent and Trademark Office (USPTO) during prosecution of the ‘018 patent,” said the Federal Circuit.

According to the defendant, the references were cited in a third-party submission in related US patent prosecution and in European opposition briefs; were “but-for” material; and were withheld by Regeneron with the specific intent to deceive the USPTO.

Prior art is but-for material if the USPTO would not have allowed a claim had it been aware of the undisclosed prior art (Therasense v Becton Dickenson & Co).

In response, Regeneron argued that the references were “not but-for material, that they were cumulative of references the USPTO actually relied on during prosecution, and that Regeneron did not have any specific intent to deceive the USPTO”.

The district court “exhaustively detailed Regeneron’s discovery misconduct throughout litigation and sanctioned Regeneron by drawing an adverse inference of specific intent to deceive the USPTO”, according to the Federal Circuit.

Regeneron appealed against the decision to the Federal Court.

“We conclude that the district court properly found that the withheld references were but-for material and were not cumulative,” said the court.

It added that Regeneron’s behaviour in the district court was “beset with troubling misconduct”.

A spokesperson for Regeneron said: “We strongly disagree with the panel majority's decision in this case—a decision that we believe misunderstands the underlying facts and science, as well as the relevant legal standard.”

They added that Regeneron will request a rehearing in the Federal Circuit en banc.

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