FDA Panel Backs Novel Bone-Building Agent.

Osteosarcoma risk must be tracked.

BETHESDA, MD. -- An injectable form of human parathyroid hormone was unanimously recommended for approval as a treatment for women with osteoporosis at a meeting of the Food and Drug Administration's Endocrinologic and Metabolic Drugs Advisory Committee.

The advisory committee, however, voted 5-4, with one abstention, to recommend that the drug be used as a second-line therapy after other first-line therapies had failed. Based on a lack of data on fractures in men, the committee was split evenly on the issue of the drug's use for men with osteoporosis.

The committee also said that their backing of teriparatide, developed by Eli Lilly and Co., was contingent on tracking the risk, if any, of osteosarcoma associated with use of the drug.

In rat studies, high doses of teriparatide significantly increased the occurrence of bone cancers. The extent of any additional risk in humans is unknown. Each year, it's estimated that osteosarcoma strikes about 4 in 1 million people aged 50 years and older. If teriparatide increases those risks, it's likely to take a long time living "with a large amount of uncertainty" before the magnitude of that additional risk is known, noted Dr. Bruce V. Stadel, an FDA medical officer who provided an independent review of the safety data on the drug.

Several committee members also supported monitoring renal function in patients taking the drug. Based on the relatively short length of follow-up in the trials, they concluded that teriparatide treatment should last no longer than 24 months.

Although not binding, the FDA usually follows the recommendations of its advisory committees.