Amgen, Inc. (NASDAQ: AMGN) lost a major patent case Thursday when a US appeals court reversed a ban on Regeneron Pharmaceuticals Inc (NASDAQ: REGN) and Sanofi SA (ADR) (NYSE: SNY)’s Praluent sales.

“Our ability to discover and deliver new medicines that benefit patients depends on meaningful patent protection and enforcement that enable significant investments in drug development and clinical trials”, an Amgen spokesperson told Benzinga.

Regeneron shares have been halted Thursday on the news.

The appeals court found that the district court erred by excluding evidence regarding written description and enablement, improperly instructing the jury on written description and improperly granting a permanent injunction.

Sanofi general counsel Karen Linehan said the company was pleased with the decision.

Amgen shares were off 1 percent, or $2.04, at $186.50.

The schedule for the new trial has not yet been determined.

Mizuho analyst Salim Syed called the ruling a “modest negative” for Amgen.

Regeneron and Sanofi applauded the federal court’s decision and said they don’t expect any new trial proceedings to start in 2017.

In January, U.S. District Judge Sue Robinson in DE took the unusual step of blocking sales of Praluent. A previous judge issued an injunction on sales of Praluent pending the outcome of the appeals process.

Zachary Silbersher, a New York-based patent lawyer not connected with the case, said the court’s ruling will make it more hard for Amgen to win if it goes to trial again, which could push the company to settle. The drugs are far more costly than other cholesterol drugs, with a list price topping $14,000 annually. Amgen is expected to continue the battle in court moving forward.