Amgen Inc. announced on Friday it has filed a lawsuit against two pharmaceutical companies for patent infringement on an experimental anti-cholesterol drug.

The Thousand Oaks company filed the lawsuit in Delaware against Sanofi and Regeneron Pharmaceuticals Inc. over an experimental drug alirocumab they are jointly developing. Amgen has three patents for a similar molecule called evolocumab.

Both drugs, which are going through clinical testing, are monoclonal antibodies that help the liver remove “bad” cholesterol from the bloodstream. The companies are in a race to get the new technology to market.

On Aug. 28, Amgen announced it had submitted an application to the Food and Drug Administration for evolocumab. In a note to investors, Matthew Rhoden, an analyst at UBS, wrote at the time that “if first to market, Amgen would be in the position to set the price and establish a nominal first mover advantage.”

On Thursday, Sanofi, a multinational drug company based in Paris, and Regeneron, a Tarrytown, N.Y. biotech, announced successful Phase 3 trial results for their version of the treatment. In the suit, Amgen seeks an injunction to prevent the manufacture, sale or use of the Sanofi-Regeneron drug.

In a note to investors, analyst Adnana Butt of RBC wrote that the lawsuit wasn’t a complete surprise and the two sides could negotiate a settlement.

“At first blush we would give Regeneron and Sanofi the benefit of the doubt,” the note stated. “At this time we do not have visibility on whether or not Amgen will be successful at delaying a launch for alirocumab.”

In other news, Amgen announced the appointment of Dr. R. Sanders Williams to its board of directors. William, 66, is a professor of medicine at the University of California, San Francisco and is president of the Gladstone Institutes, a San Francisco biomedical research organization focused on nervous system disorders.

Shares of Amgen closed up $3.24 , or 2.5 percent, to $133.69 on the Nasdaq.