UPDATE 2-Amgen bone drug wins in cancer trial, shares jump

* Shares surge almost 13 percent in after-hours trade

* Denosumab reduces or delays bone complications

* Infrequent jaw deterioration seen, similar to Zometa (Adds trial results details)

NEW YORK, July 7 - Amgen Inc said its experimental osteoporosis drug reduced and delayed serious bone complications among patients with advanced breast cancer, and the news sent its shares up almost 13 percent in after-hours trade.

The biotechnology company said on Tuesday its drug, denosumab, proved superior to Novartis AG's Zometa in a late-stage study.

Bone metastases, or the spread of cancer to the bone, are a serious consequence of breast cancer, weakening or destroying bone around the tumor.

The Phase 3 study assessed the incidence of serious bone complications, or SREs, among 2,049 such patients, including fractures, or the need for radiation or surgery to bone.

Patients were divided into groups that received either monthly injections of denosumab or a 15-minute infusion of Zometa each month.

Denosumab significantly delayed the time to the first SRE, meeting its primary trial goal of non-inferiority to Zometa. Moreover, it significantly reduced first and subsequent SREs, secondary goals of the study, Amgen said.

"We are extremely pleased with the outcome of this important study, which shows that denosumab can reduce or delay the serious complications of bone metastases in breast cancer patients better than the current standard of care, and with a favorable benefit/risk profile," Roger Perlmutter, Amgen's research chief, said in a press release.

Overall incidence of serious side effects was consistent with that seen in earlier studies of denosumab and Zometa, Amgen said.

But Amgen noted that osteonecrosis -- or deterioration -- of the jaw was seen at the same infrequent incidence in both treatment groups, although the problem had not been seen in previous late-stage trials of denosumab. The worrisome jaw condition has previously been linked to Merck & Co's widely used Fosamax osteoporosis treatment.

Full results of the denosumab trial will be presented at a medical meeting later this year, Amgen said.

Amgen is awaiting U.S. approval of denosumab as a treatment for post-menopausal osteoporosis. Potential use of the medicine to avert bone damage among cancer patients could provide a lucrative additional sales avenue for the company's most valuable experimental medicine.

Amgen, based in Thousand Oaks, California, is one of the world's biggest biotech companies, but has posted disappointing sales in recent quarters due to concerns about the safety of its anemia drugs and the impact of the global recession.

It is counting on denosumab to turbo-charge its future revenue and earnings.

Shares of Amgen were trading at $58.96 after closing at $52.23 on the Nasdaq.