Shares of Thousand Oaks-based biotech giant Amgen Inc. lost 2 percent Friday after the Food and Drug Administration announced new label warnings for a class of treatments that includes the company’s top-selling drug, Aranesp.

The FDA said that three anemia-treatment drugs, Amgen’s Aranesp and Epogen, and Johnson & Johnson’s Procrit (which is Epogen under license), will carry new warnings indicating the increased risk of death, heart trauma, blood clots and tumor growth when used above recommended doses.

Doctors have been prescribing the drug at “off-label” doses to treat anemia in cancer patients not undergoing chemotherapy.

Combined sales of Aranesp and Epogen were more than $6 billion worldwide for Amgen in 2006.

Shares of Amgen Inc. closed at $60.86, down $1.31, or 2.2 percent, Friday in trading on the Nasdaq.