Aranesp Data Dents Amgen

Amgen(AMGN Quote) released Friday an interim analysis from another cancer study of Aranesp that showed the anemia drug doesn't help patients, and may in fact harm them.

Executives with the Thousands Oak, Calif.-based biotech firm cautioned that the results from the independent study conducted by a German cancer group are preliminary and therefore no firm conclusions should be made.

But the news, released after the close of regular trading, sent shares of Amgen down $2.25, or 4%, to $53 in the after-hours session. The stock ended regular trading down 21 cents to $55.25. ...