Amgen dealt another blow in closely watched PCSK9 patent case against Sanofi, Regeneron

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Amgen suffered another loss in the PCSK9 patent fight with Sanofi and Regeneron. (Getty Images)

Amgen’s high-profile PCSK9 patent fight with Sanofi and Regeneron has attracted a who’s who of biopharma observers over the years, with many top companies voicing support for each side. Now, Amgen has suffered its third consecutive loss in the case. 

In a Monday order (PDF), the U.S. Court of Appeals for the Federal Circuit declined Amgen's request for a rehearing of a prior patent loss on PCSK9 cholesterol drug Repatha. With the decision, Amgen can either try to appeal further or drop the issue. A spokesman didn't immediately respond to a request for comment.

The case stems back to 2014, when Amgen sued partners Sanofi and Regeneron over alleged PCSK9 patent infringement. Amgen asked the court to back broader patent protections on antibody drugs such as its PCSK9 drug Repatha. Without broader protections, Amgen and other companies have argued, me-too drugs can come in and make minor changes to a successful medicine without committing resources to research.

Sanofi, Regeneron and their supporters said Amgen's patent claims, if upheld, could allow companies to stake off entire classes of new drugs.

After a March 2016 trial, a jury initially favored Amgen's side of the argument, forcing Sanofi and Regeneron to pull their new launch Praluent from the key U.S. market. While temporary, the injunction came at a crucial time in the drug's launch. 

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

After Amgen's appeal, the U.S. Court of Appeals for the Federal Circuit in February deemed several Amgen patent claims invalid. That prompted the latest petition for a rehearing. 

RELATED: GlaxoSmithKline backs Amgen in PCSK9 patent fight, arguing court decision could 'devastate' R&D incentives

While PCSK9 cholesterol drugs aren't among the industry's bestselling medicines, the case garnered attention throughout biopharma because of its potential patent implications. During the litigation, Pfizer and Eli Lilly backed Sanofi and Regeneron, while Bristol Myers Squibb and Merck sided with Amgen. 

In an amicus brief back in April, GlaxoSmithKline argued the decision against Amgen could “devastate” R&D incentives in the industry. GSK's lawyers said the decision imposes “obstacles that prevent innovators from recouping a fair return on their investments and for their contributions to science.” 

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

Writing in an opinion Monday, three judges said Amgen and its backers seem to believe the “sky is falling.” The judges wrote that Amgen was “trying to control what it has not invented.”