Amgen drug delayed spread of prostate cancer to bones, study finds

The Amgen drug denosumab delayed the spread of prostate cancer to men’s bones, a company study found, sending shares of the Thousand Oaks firm higher Tuesday.

Use of the drug stalled the malignancy’s spread by 4.2 months, Amgen said. The study, part of the final phase of testing usually needed for U.S. approval, didn’t find a survival benefit.

Amgen Inc. markets the drug as Xgeva for use in cancer treatment. If the drug can also win U.S. clearance to prevent breast cancer from moving into bone, it may add $2 billion in sales, said Eric Schmidt, a Cowen & Co. analyst in New York. The drug was approved Nov. 18 to reduce fractures after tumors had already migrated to bones.

Amgen shares rose $2.65, or 4.9%, to $56.76.

Denosumab targets a protein called RANK ligand that Amgen scientists discovered in the mid-1990s. This protein works with others in a process that breaks down old bone in the body and replaces it with new. It also plays a role in weakening the bones of people with osteoporosis and cancer.

The drug entered the U.S. market in June when a lower-dose version, sold under the name Prolia, won approval from the Food and Drug Administration to treat osteoporosis in older women.

Amgen started a trial in June that aims to enroll 4,500 women with breast cancer to see if Xgeva can delay or prevent the malignancy from spreading to their bones. That study’s results aren’t expected to be released until about 2016, said Roger Perlmutter, Amgen’s executive vice president for research and development.

“We feel that the success of the prostate cancer study certainly augurs well for the ultimate outcome of the breast cancer study,” he said.

Amgen will analyze data from the prostate cancer study of 1,432 men, and meet with regulators, before deciding whether to seek approval for that indication, Perlmutter said.