A third pivotal trial of Amgen Inc’s denosumab found that it significantly delayed the likelihood of suffering fractures and other bone complications in men with advanced prostate cancer compared with current therapy.

The 1,900-patient trial, which compared denosumab with Novartis AG’s Zometa, showed that the Amgen drug delayed by 3.6 months patients’ first skeletal event, such as a fracture or the need for bone surgery.

A different Phase III trial of Zometa showed that it improved survival and significantly reduced the risk of bone-related problems in patients with newly diagnosed multiple myeloma, a type of blood cancer, compared to another drug in its class.

Denosumab, widely considered the most important growth driver in Amgen’s development pipeline, is the first in a new class of drugs designed to inhibit proteins that activate bone-destroying cells.

Zometa is a bisphosphonate that is the current standard of care for treating cancer patients whose disease has spread to the bone.

Amgen has said its drug is unlikely to cause the kind of kidney toxicity associated with the bisphosphonate, and it believes that the fact that denosumab is given by injection, rather than an intravenous infusion, is an advantage.

‘REMARKABLY CONSISTENT’

Amgen filed last month for U.S. Food and Drug Administration approval of denosumab as a treatment for cancer patients. Earlier this week, the agency approved it, under the brand name Prolia, for use in post-menopausal women suffering from osteoporosis.

Roy Baynes, head of hematology/oncology development at Amgen, said the latest trial results, presented here at a meeting of the American Society of Clinical Oncology, are “remarkably consistent” with previous trials in patients with advanced breast cancer, other solid tumors and multiple myeloma.

The trial found no difference between the two groups in overall survival or the amount of time patients lived without their cancer getting worse.

Baynes said the rates of adverse events, including infections, were similar between the two treatment groups, but the incidence of low blood calcium levels was more frequent in the denosumab arm.

Osteonecrosis of the jaw — death of jaw bone tissue — was seen in 22 patients receiving denosumab, compared with 12 patients receiving Zometa. Baynes said encouraging information about those patients will be detailed at the oral presentation of the study here on Sunday.

Amgen expects to announce in the second half of this year results from a pivotal trial looking at whether use of denosumab in patients with earlier-stage prostate cancer can prevent the disease from spreading to the bones.

“We believe we have a molecule that has a very favorable profile,” Baynes said.

The consensus analyst forecast is for denosumab to reach about $3.3 billion in sales in 2014, according to Thomson Reuters data.

The Novartis trial showed that adding Zometa, also known as zoledronic acid, to chemotherapy improved overall survival for multiple myeloma patients by 16 percent compared with oral clodronate, an older bisphosphonate, plus chemotherapy.

The study also showed that Zometa reduced the relative risk of bone problems 24 percent more than clodronate. By Deena Beasley,  Yahoo Daily News