Regeneron, Sanofi score again in long-running PCSK9 patent fight with Amgen

Amgen's years-long PCSK9 patent crusade has swung once again in Sanofi and Regeneron’s favor.

Upholding a lower court’s ruling, the U.S. Federal Circuit Court said it found (PDF) Amgen’s arguments “unpersuasive” and deemed several of the company's patent claims invalid.

Regeneron's general counsel Joseph LaRosa said in a statement the decision "affirms our longstanding position that Amgen's patents claiming PCSK9 antibodies purely by their function are overly broad and invalid." The ruling helps "provide closure on this matter," he said.

The ruling will come as a relief to drugmakers worried an Amgen win would allow drugmakers that identify antibody targets to corner the market. But other companies, including Bristol Myers Squibb and Merck & Co., had argued an Amgen loss could erode patent protections across the industry.

The PCKS9 rivals have been battling in court for years. First, Amgen sued in 2014 alleging infringement. The sides took the case to trial in March 2016, and a jury favored Amgen, forcing Regeneron and Sanofi to pull Praluent from the key U.S. market.

That move was temporary, but it came at a crucial time in the drug's launch and gave Amgen a chance to claim market share—gaining a lead that Praluent was never able to make up.

The federal appeals court later found procedural errors and sent the case back for a new trial, where a jury upheld certain Amgen patent claims and tossed others aside. Amgen demanded an injunction to keep Praluent off the market, while Sanofi and Regeneron asked trial judge to overturn the jury's verdict. The judge sided with Sanofi and Regeneron.

RELATED: Sanofi, Regeneron score win against Amgen patents on PCSK9 med Repatha

All along, other drugmakers had been watching closely and voicing support of both sides.  

Amgen's patent claims, if found legitimate, could allow another company in another field to stake off an entire class of drugs, Sanofi’s legal team previously said. Pfizer, Eli Lilly and Ipsen urged the court to rule in favor of Sanofi and Regeneron. AbbVie favored Amgen’s argument.

In a filing for the latest appeal, Bristol Myers and Merck sided with Amgen. They said the lower court’s decision, if it became a precedent, would “make it effectively impossible for innovator companies to obtain sufficiently broad patent protection.”

Amgen said in a statement it's "disappointed" in the court's ruling and that it "firmly" believes the patent is valid.

"Amgen believes that patent protection is essential not only for Amgen but also for the entire biotechnology and pharmaceutical industry to make the significant investments required to discover and develop new innovative therapeutics that serve unmet patient needs," a spokesperson said.

RELATED: Lilly, Pfizer, et al. back Sanofi and Regeneron in PCSK9 patent appeal. AbbVie doesn't

Initially, market watchers thought the legal saga might carry blockbuster stakes for the PCSK9 companies. In reality, the drugs have failed to live up to early expectations because high launch prices prompted payers to put up barriers to access. In response, the companies discounted their drugs to win spots on key payer formularies.

Last year, Regeneron’s Praluent sales reached $186 million, while Amgen reported $459 million in Repatha sales.