Anti-osteoclast monoclonal antibody prevents bone loss in prostate cancer

July 14, 2008

LOS ANGELES (Reuters) - In a study, Amgen Inc's experimental drug denosumab reduced the risk of osteoporosis and fracture in men with prostate cancer undergoing androgen ablation, the company said on Monday.

A three-year study of more than 1,400 men with non-metastatic prostate cancer undergoing androgen deprivation therapy showed denosumab, a bioengineered antibody that targets osteoclasts, produced greater increases in bone mineral density at the lumbar spine and non-vertebral sites than a placebo.

Men receiving denosumab also experienced less than half the incidence of new vertebral fractures as those receiving the placebo, Amgen said.

Both findings were statistically significant, it said. There were also fewer non-vertebral fractures in the denosumab patients, but the difference was not statistically significant.

"We're excited by the evidence of clinical activity -- which is reduction of vertebral fractures," said Roger Dansey, director of Amgen's denosumab oncology program. He said the study also confirmed previous trial results showing that denosumab increases bone mineral density.

In the study, about 6% of men treated with denosumab developed serious infections, compared with 5% of patients given a placebo.

Some earlier trials have shown an even higher risk of infection with denosumab, leading to questions about whether the drug's safety profile will be adequate for regulatory approval.