Amgen Inc. said Monday it had received positive results from clinical tests of an experimental heart medication that it hopes will be one of its next blockbuster drugs.

The Thousand Oaks biotech says the drug, called AMG 145, reduces cholesterol in patients who have experienced negative side effects such as muscle aches from statin drugs such as Pfizer Inc.’s Lipitor.

Statins inhibit an enzyme that produces cholesterol, while the new Amgen drug affects a cholesterol-regulating protein in the liver. The phase two trials, the first on humans, reduced bad cholesterol 51 percent in statin-intolerant patients after 12 weeks.

“Close to a million people in the USA alone who are treated with statins cannot tolerate them, or the doses needed for effective cholesterol control,” said Dr. Evan Stein, director of the Metabolic and Atherosclerosis Research Center, in a statement.

Amgen must still conduct additional clinical trials on humans and then submit those results to the Food and Drug Administration before the drug can be approved for sale. Rivals including Pfizer are also competing to be the first to market with similar new medicines.

A cholesterol drug would be a huge boost for the company given that its blockbuster anemia drugs Aranesp and Epogen will face competition from generic versions in 2015. The two drugs together are expected to general $4 billion in revenue for Amgen this year.

Shares closed down 10 cents, or less than 1 percent, to $86.35 on the Nasdaq.