FDA Approves First Drug Against Cancer Treatment-Induced Bone Loss

The Food and Drug Administration this week approved denosumab (Prolia; Amgen) to increase bone mass and prevent fracture among women taking aromatase inhibitors for breast cancer, and among men receiving anti-androgen therapy because of prostate cancer. This is the first approval of a drug intended to prevent adverse effects on bone structure from cancer treatments that target hormones.

The approval is based on two Phase 3 trials, a 3-year randomized multinational study including 1,468 men treated with androgen deprivation therapy and a similar 2-year study involving 252 postmenopausal women treated with aromatase inhibitors for breast cancer. Both trials showed significant improvements in bone mineral density and reduced incidence of fractures among denosumab-treated subjects, compared to controls.

The approval is a hopeful sign for cancer patients at risk of fractures caused by their treatment, but for many cancer patients this may come too late. A recent prospective study from France found that 20% of postmenopausal women already had vertebral fractures at the time they began aromatase inhibitor treatment for breast cancer. Men with advanced prostate cancer appear to be at even greater risk: A prospective study from the UK found that more than half showed vertebral fractures on thoracolumbar x-rays before beginning androgen deprivation therapy.

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