US appeals court overturns ban on sales of Sanofi, Regeneron's PCSK9 inhibitor Praluent; orders new trial

A US appeals court on Thursday dismissed a lower court ruling barring Sanofi and Regeneron Pharmaceuticals from marketing the PCSK9 inhibitor Praluent (alirocumab) and ordered a new trial‎. The ban was instituted in January after a lower court determined that the drug infringed patents held by Amgen for Repatha (evolocumab). An appeals court later suspended the ban pending the outcome of Sanofi and Regeneron's appeal. 

In its decision, the appeals court ruled that the jury in the original trial was given improper instructions. Specifically, the appeals court found that jurors could have been incorrectly led to believe that describing a protein such as PCSK9 was sufficient for patenting a large class of potential antibodies. The court also concluded that the US district court judge improperly excluded evidence from Sanofi and Regeneron. 

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Sanofi general counsel Karen Linehan stated "we are pleased with the Federal Circuit's decision to remand for a new trial that allows us to present our complete evidence to the jury," adding "it is our longstanding position that Amgen's asserted patent claims are invalid, and we remain confident in the long-term availability of Praluent for patients." Sanofi and Regeneron indicated that they do not expect the new trial to begin this year. 

Meanwhile, Amgen expressed disappointment in the ruling but said it was encouraged that the court rejected the argument that limiting drug choice always hurt the public interest. "We firmly believe in the validity of our patents and we look forward to reasserting our rights in court," the firm said. 

Commenting on the news, Mizuho analyst Salim Syed described the decision as a "modest negative" for Amgen, adding "the bottom line here is that there is no definitive winner or loser yet in this litigation." The analyst cautioned that although the ruling will likely keep Praluent on the market for at least another year, there is no guarantee that the drug will not eventually be withdrawn. 

Praluent was cleared by the FDA in 2015 for treating high cholesterol in select patients, making it the first PCSK9 inhibitor approved in the US. Repatha was authorised in the country the following month. 

For related analysis, read ViewPoints: Patients, payers unlikely to rue appellate ruling in PCSK9 legal battle.

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