The U.S. Food and Drug Administration rejected an application by Amgen Inc to expand the use of its drug Xgeva to slow the spread of tumors to the bones of patients suffering from advanced prostate cancer.

Xgeva, which went on the market last year, is approved to prevent fractures in patients with advanced prostate cancer that already has migrated to the bone. The Thousand Oaks biotech is counting on Xgeva and sister osteoporosis drug Prolia to become billion-dollar blockbusters to fuel growth as its anemia, infection and inflammation drug franchises mature.

In the first quarter, Xgeva sales rose 14 percent from the fourth quarter to $153 million.

The FDA said in its letter that reviewers determined that the risks of taking Xgeva outweigh the level of benefit to prostate cancer patients that based on the clinical trial data provided. It asked Amgen to supply additional trial data, the company said late Thursday night.

"We will work with FDA to determine any next steps," said Sean Harper, Amgen’s executive vice president of research and development. “The FDA's action does not impact the (already) approved indication of Xgeva.

The new use for Xgeva would potentially target about 50,000 men in the United States who have advanced prostate cancer. Amgen also is testing the injectible drug as a treatment for patients with breast, lung and other cancers that also can spread to the bone.

Shares closed up 85 cents, or 1.2 percent, to $71.64 on the Nasdaq.

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