New drug shown to preserve bone: vertebrae density increases in two high-risk populations.

A new drug increases bone density and reduces the number of fractures in men fighting prostate cancer and in elderly women with bone loss, researchers report in two studies appearing August 11 in the New England Journal of Medicine.

The results of these clinical trials might clear the way for approval of the drug, called denosumab, by the Food and Drug Administration. "This certainly goes a long way toward fulfilling the criteria the FDA uses," says Sundeep Khosla of the Mayo Clinic in Rochester, Minn.

Denosumab prevents old bone from being dissolved faster than it can be replaced. While bone mineral removal and replacement is a natural balancing act, the loss of hormones--as in postmenopausal women lacking estrogen and men with prostate cancer who are being treated with androgen-deprivation therapy--can put it out of sync.

In one of the new studies, researchers enrolled 1,468 prostate cancer patients, average age 75, who were undergoing androgen-deprivation treatment. Half the volunteers received a denosumab injection every six months for three years, while the others got placebo shots. Those getting the drug showed on average a 5.6 percent increase in vertebrae density in the lower spine after two years, compared with a 1 percent loss in the placebo group. Only 1.5 percent of the men receiving denosumab experienced a vertebra fracture by the end of the third year compared with 3.9 percent of the placebo recipients.

"This demonstrates clinically meaningful improvements in bone density" says coauthor Matthew Smith of Massachusetts General Hospital Cancer Center and Harvard Medical School in Boston.

In the other study, an international team identified nearly 8,000 women, average age 72, with low bone-density scores. Half received denosumab shots every six months for three years, while the others got placebo injections. The bone density of vertebrae rose, on average, by 9.2 percent and hip bone density by 6 percent in women getting denosumab, whereas women in the placebo group showed no gains. Also, 2.3 percent of women getting denosumab had a vertebra fracture, compared with 7.2 percent of the placebo group.