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FDA Advisory Panel Recommends Approval of Bone-Forming Drug to Treat Osteoporosis in Women

An advisory panel to the U.S. Food and Drug Administration (FDA) has unanimously recommended the approval of the bone-forming drug Forteo (generic name, teriparatide) to help treat post-menopausal women with osteoporosis, a degenerative bone disease. The FDA is not required to follow its advisory panel’s recommendation but usually does so. In clinical trials, Forteo significantly reduced the incidence of spinal and non-spinal fractures and increased bone mineral density in post-menopausal women with osteoporosis. However, the FDA advisory panel expressed concerns about the safety of Forteo because the drug increased the risk of a certain type of bone cancer called osteosarcoma in studies with rats, and though similar results were not seen in humans, clinical trials were stopped early because of the potential risk. The FDA advisory panel was also split five-to-five on its recommendation to approve Forteo to treat osteoporosis in men.

According to Eli Lilly, the maker of Forteo, 25 clinical trials were conducted during the development of Forteo and included a total of 2,800 men and post-menopausal women with osteoporosis. In the most recently published data on Forteo, researchers followed 1,637 post-menopausal women with osteoporosis-related fractures. After an average follow-up of 18 months, the women who received Forteo were nearly 90% less likely to experience severe or moderate spinal fractures when compared to those who received a placebo (an inactive pill). Women who received Forteo were also less likely to experience non-spinal fractures at sites such as the wrist, hip, ankle/foot, ribs, etc. than women who did not receive Forteo. Additionally, women who received Forteo experienced increases in bone mineral density as early as three months after beginning treatment.

Forteo is the first in a new class of investigational drugs that treat osteoporosis by increasing the number and/or activity of bone-forming cells called osteoblasts. Other FDA-approved osteoporosis drugs such as Fosamax (generic name, alendronate) and Actonel (risedronate sodium) work by slowing the rate of bone loss but do not help the body form new bone.

"Today’s recommendation for the approval of the bone formation agent Forteo represents an important step forward in treating these patients [who have suffered fractures or lost substantial amounts of bone]," said Dr. Felicia Cosman, Medical Director of the Clinical Research Center in Helen Hayes Hospital and Clinical Director of the National Osteoporosis Foundation, in an Eli Lilly news release.

Though the FDA advisory panel recommended the approval of Forteo, they did express concern over the safety of the drug. Previous studies with rats had shown that Forteo increased the risk of osteosarcoma, a rare type of bone cancer, by 29 to 225 times. According to FDA official Gemma Kuijpers, PhD, the potential risk of osteosarcoma to humans using Forteo cannot be excluded. While Eli Lilly maintains that no increased risk of osteosarcoma was seen in humans, clinical trials with Forteo were stopped early because of the possibility. The FDA advisory panel said that approval of Forteo should be contingent upon strict post-marketing studies or patient registries to determine if any osteosarcoma cases arise from the use of Forteo. The advisory panel was also split on its recommendation of Forteo for men, citing a lack of evidence that Forteo can prevent bone fractures in men.

Side effects of Forteo were generally mild in the studies and included dizziness, legs cramps, headache, and nausea. One drawback to Forteo is that it must be injected by the patient or a healthcare provider, making it less convenient than an oral medication (such as Fosamax or Evista). However, patients who participated in the studies of Forteo quickly learned how to self-inject the drug.

Eli Lilly does not know when the FDA will make a final decision on whether Forteo should be approved for general use. The FDA usually follows the recommendation of its advisory panel but is not required to do so.

Other FDA-approved drugs to help prevent and/or treat osteoporosis include:

Osteoporosis is a degenerative bone disease that primarily affects post-menopausal women. It is estimated that one in two women over 50 will have an osteoporosis-related fracture. Osteoporosis is a threat to 28 million Americans and is currently one of the most under-diagnosed and under-treated disorders in medicine.

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