A federal judge in Delaware ruled Jan. 5 that Sanofi and Regeneron Pharmaceuticals could not market or sell their proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor in the U.S.

The companies said in a news release that the court delayed the injunction for 30 days. During that time, the companies plan on appealing the verdict and filing a motion of stay of an injunction during the appeal process.

The judge ruled that Sanofi and Regeneron violated two patents that Amgen had obtained for evolocumab (Repatha), a PCSK9 inhibitor which the FDA approved in August 2015 to lower low-density lipoprotein cholesterol. In July 2015, the FDA approved Sanofi and Regeneron's PCSK9 inhibitor, which is known as alirocumab (Praluent).

The ruling mentioned that Amgen began developing evolocumab since 2005. The FDA approved evolocumab in 140 mg and 420 mg doses and approved alirocumab in 75 mg and 150 mg doses.

In March, a jury sided with Amgen and ruled that Sanofi and Regneron had infringed on seven of Amgen’s patents related to the PCSK9 inhibitor.

"We will immediately appeal today's ruling, along with the jury's earlier finding upholding the validity of Amgen's patents," Karen Linehan, Sanofi's executive vice president and general counsel, said in a news release. "It is our longstanding position that Amgen's patent claims are invalid and that the best interests of patients will be greatly disserved by an injunction preventing access to Praluent."

Amgen said in a Jan. 5 news release that it could provide evolocumab to patients who would like to switch from alirocumab.

A Bloomberg report said analysts projected sales of alirocumab to reach $2 billion by 2020. Meanwhile, sales of evolocumab are expected to reach $1.08 billion in 2018, although those projections would likely increase if Sanofi and Regeneron cannot sell alirocumab in the U.S.