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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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