Men undergoing androgen deprivation therapy (ADT) for non-metastatic prostate cancer experienced a 62% reduction in risk of vertebral fractures when treated with denosumab compared to men treated with placebo, according to the results of a study published in the New England Journal of Medicine.
Hormone therapy for prostate cancer, or androgen deprivation therapy (ADT), involves the suppression of testosterone levels—an approach that may result in loss of bone density and an increased risk of fracture. Studies show that men experience a rapid loss of bone mineral density (BMD) within the first six to 12 months of ADT.
Denosumab is an investigational drug that targets a protein known as the RANK ligand. This protein regulates the activity of osteoclasts (cells that break down bone). Denosumab has shown promising results in the management of bone metastases, bone loss due to cancer treatment, and postmenopausal osteoporosis.
The HALT Study involved 1,468 men undergoing ADT for non-metastatic prostate cancer. Half the men were given denosumab every six months for three years and half were given a placebo. The results showed that men in the denosumab group were 62% less likely than men in the placebo group to develop a new vertebral fracture.
The men receiving denosumab experienced a 6.7% increase in bone mineral density (BMD) at the lumbar spine at 24 months, though increases in BMD were observed as early as one month after initiating treatment with denosumab and continued to increase throughout the study. In addition, men receiving denosumab experienced increases in BMD at non-vertebral sites compared to those receiving placebo: total hip 4.8%, femoral neck 3.9%, and distal 1/3 radius 5.5%.
Denosumab appeared to be safe and effective, as the rate of adverse events were similar in both groups: the rate of serious adverse events were 35% for denosumab and 31% for placebo.
The researchers concluded that denosumab was safe and effective and increased BMD while decreasing the risk of fractures in men receiving ADT for non-metastatic prostate cancer. The results of denosumab were observed as early as one month into treatment and sustained for three years.
 Smith MR, Egerdie B, Hernandez Toriz N et al. Denosumab in men receiving androgen-deprivation therapy for prostate cancer. New England Journal of Medicine. Early online publication August 11, 2009.
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