Regeneron and Sanofi Ordered to Withdraw PCSK9 Inhibitor Praluent from Market

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A judge ruled that Regeneron’s mAb be removed from the market after Amgen alleged that the marketing of Praluent hurt its reputation as innovator of this class of drugs.

A federal judge ruled on Jan. 5, 2016 that Regeneron and Sanofi must pull the monoclonal antibody (mAb) Praluent (alirocumab) from the market because it allegedly infringes two Amgen patents that describe and claim monoclonal antibodies to proprotein convertase subtilisin/kexin type 9 (PCSK9). Amgen has a similar mAb on the market that treats heterozygous familial hypercholesterolemia (HeFH), homozygous familial hypercholesterolemia (HoFH), and clinical atherosclerotic cardiovascular disease.

Both Praluent and Repatha facilitate the removal of low-density lipoprotein from the blood by blocking the protein PCSK9. Compared with placebo, Repatha reduced low-density lipoprotein (LDL) by approximately 60%, while trial participants taking Praluent had an average reduction in LDL cholesterol ranging from 36–59%. PCSK9 inhibitors are thought to help reduce the risk of a cardiovascular event, although investigations about this assertion continue.

The move is surprising, especially considering Regeneron’s cholesterol-lowering medication hit the United States market first, nearly a month before Amgen’s Repatha (evolocumab). Although Amgen’s drug initially had an action date before Regeneron’s version, Regeneron’s inhibitor received Priority Review from FDA as a result of a voucher the company purchased from BioMarin for nearly $68 million. To add another wrinkle, Amgen’s Repatha was actually approved in Europe prior to either drug’s approval in the US.

According to an Amgen press release, Sanofi and Regeneron actually admitted in some capacity that they had infringed Amgen’s patents in the manufacture of Praluent. Regeneron countered in a press release, however, that it believes Amgen’s patents to be invalid because they exceed the scope of the original discovery and plans to appeal the court’s decision. In the meantime, Praluent will be pulled from the market in 30 days unless the decision is overturned. Amgen said it could immediately fill the hole in the market and supply its product to patients wishing to switch from Praluent to Repatha.


Regeneron believes that the products are not equivalent anyway; it argues its product offers a competitive advantage. According to a press release, “Praluent is the only PCSK9 inhibitor that offers two doses with two levels of efficacy, allowing healthcare providers the flexibility to adjust the therapeutic dose based on their patient's LDL cholesterol-lowering needs." An injunction, said Regeneron, would harm the treatment of patients on the low-dose version of the drug. Regeneron also marketed its product as the “first” approved in the US, which Amgen claimed caused “harm to their reputation as the innovator in the PCSK9 cholesterol-lowering medicine.”

Both drugs are exceedingly expensive, and were tagged as having the potential to be the highest-selling class of medication in history. Praluent and Repatha are currently the only PCSK9 inhibitors on the market. Their approvals caused payers to begin pitting the drugs against one another, effectively lowering the price of both drugs. In the ruling, Amgen said the existence of Regeneron’s drug caused the company “irreparable harm.” Amgen said it would not be pacified by royalties from Regeneron, as Amgen intended to use its patent “to maintain market exclusivity.” 

Sources: Amgen, Regeneron