Biotech drug manufacturer Amgen Inc. announced on Monday that its experimental drug denosumab reduced the risk of osteoporosis and fracture in men with prostate cancer treated with drugs that cause bone loss.

Denosumab is a bioengineered antibody that targets a protein involved with bone-destroying cells called osteoclasts.

The drug was tested on more than 1,400 men with non-metastatic prostate cancer undergoing androgen deprivation therapy. After a three-year follow-up period, denosumab produced greater increase in bone mineral density at the lumbar spine and non-vertebral sites than a placebo.

The study also met a secondary endpoint, as men on denosumab also experienced less than half the incidence of new vertebral fractures than those on placebo. Incidence of non-vertebral fractures was also reduced in the denosumab patients, but not statistically significant, Amgen said.

Side effects of the drug were minimal. More exactly, about 6 percent of patients on denosumab developed serious infections compared to 5 percent of those receiving a placebo.

“We’re excited by the evidence of clinical activity – which is reduction of vertebral fractures,” Roger Dansey, director of Amgen’s denosumab oncology program, said as quoted by Reuters.

He added that the study confirmed previous trial results showing that the drug increases bone mineral density in women with breast cancer receiving aromatase inhibitor therapy. The company is expecting results of another trial involving denosumab in women with post-menopausal osteoporosis later this year.

Denosumab is involved in one of the largest programs in Amgen’s history. The company currently has trials involving more than 19,000 patients globally.

The company should have all of data for its first denosumab filing with US regulators by the end of 2008, according to Amgen’s representative Lisa Rooney.

The American Cancer Society estimates there will be more than 186,000 men diagnosed with prostate cancer this year and almost 29,000 will die from the disease.