PCSK9 Inhibitor Patent Dispute: Regeneron and Sanofi Win Latest Round Against Amgen

PCSK9 Inhibitor Patent Dispute: Regeneron and Sanofi Win Latest Round Against Amgen

Regeneron and Sanofi, makers of the LDL-cholesterol-lowering drug Praluent, have been embroiled in a patent dispute with Amgen over the PCSK9 inhibitors.

In the latest round of Amgen’s (NASDAQ: AMGN) ongoing patent battle against Regeneron (NASDAQ: REGN) and Sanofi over LDL-lowering PCSK9 (proprotein convertase subtilisin/kexin type 9) antibodies, the latter came out with a win last week. The US Federal Circuit Court said it found Amgen’s arguments “unpersuasive,” deeming several of the company’s patent claims for Repatha (evolocumab) invalid. The ruling upheld an earlier decision by the US District Court for the District of Delaware.

With the Federal Circuit ruling, Regeneron and Sanofi were successful in nullifying all five of Amgen’s asserted claims pertaining to Praluent (alirocumab).

Other pharma companies may be relieved with the latest ruling, as many worried that an Amgen win may allow drugmakers that identify antibody targets to bully their way into an unfair advantage in the market. However, other companies, including Bristol Myers Squibb and Merck & Co., were found to be favoring Amgen, believing that the drugmaker’s loss could threaten patent protections across the industry.

Praluent has been developed jointly by Sanofi and Regeneron, and the drugmakers are partners on a number of other collaborations.

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Joseph LaRosa, executive vice president, general counsel and secretary, Regeneron, said in a statement from the company: “We are pleased with today’s decision by the Federal Circuit, which affirms our longstanding position that Amgen’s patents claiming PCSK9 antibodies purely by their function are overly broad and invalid.” He said that, “Praluent was developed using Regeneron’s proprietary technology, and the Federal Circuit validated that Amgen has no claim to Praluent or its development, helping to provide closure on this matter.”

Meanwhile a spokesperson from Amgen said, “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.”

Battle Beginnings

The PCKS9 rivals have been battling it out in court for years now. It began when Amgen first sued Regeneron in 2014, alleging patent infringement. The case was brought to trial in March 2016, with the first ruling going in favour of Amgen, which forced Regeneron and Sanofi to pull Praluent from the major US market.

However, the move was temporary, as the federal appeals court later found procedural errors and sent the case for a new trial — opportune timing which gave Amgen the chance to claim market share. This led Amgen to a head start while Praluent got left behind and could never quite catch up. In the new trial, a jury upheld some of Amgen’s patent claims while discarding others.

The drama continued as Amgen demanded an injunction to keep Praluent off the market. Regeneron and Sanofi rebutted by asking the trial judge to overturn the jury’s verdict, which the judge did, swinging the case in favor of the two pharma giants.

Industry watchers expected the legal battle to help fuel skyrocketing PCSK9 inhibitor sales. However, high launch prices led insurers to back away and put up barriers to access. This prompted the companies to slash prices on their drugs to secure spots on key payer formularies.

In 2020, Regeneron’s Praluent sales hit $186 million, while Amgen had $459 million in sales for Repatha.


Praluent blocks PCSK9 from binding to the low-density lipoprotein (LDL) receptor in aims of increasing the number of free LDL receptors on the surface of liver cells capable of clearing so-called “bad” LDL cholesterol (LDL-C) from the blood.

Praluent was developed by Regeneron and Sanofi under a global collaboration agreement and invented by Regeneron using the company’s proprietary VelocImmune technology that yields optimized fully-human monoclonal antibodies.

Praluent is approved in more than 60 countries around the world, including the US, the EU, Japan, Canada, Switzerland, Mexico and Brazil. In the US, Praluent is approved to reduce the risk of heart attack, stroke and unstable angina that requires hospitalization in adults with diagnosed cardiovascular disease.

The drug is also indicated as an adjunct to diet, alone or in combination with other lipid-lowering therapies such as statins and ezetimibe, for the treatment of adults with primary hyperlipidemia (including heterozygous familial hypercholesterolemia) to reduce LDL-C.


Similar to Praluent, Repatha is a monoclonal antibody that inhibits PCSK9, preventing its binding to the LDL receptor. This prevents PCSK9-mediated degradation of the receptor, allowing it to be recycled back to the surface of liver cells. This helps increase the number of LDL receptors to clear LDL from the blood to lower LDL-C levels.

It was approved by the US Food and Drug Administration (FDA) in 2017 to reduce the risk of myocardial infarction, stroke and coronary revascularization in adults with established cardiovascular disease. It is also indicated for the treatment of patients with the inherited condition of homozygous and heterozygous familial hypercholesterolemia. For these patients, it is approved for use in conjunction with diet modification and other LDL-lowering treatments in cases where LDL must be further lowered.

Repatha is approved in more than 50 countries, including the US, Japan, Canada and in all 28 EU countries.