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In a clinical trial, the drug Forteo reduced the risk of broken bones and was the first to actually promote growth.
By WES ALLISON
© St. Petersburg Times, published May 10, 2001
An experimental drug helps rebuild bone and significantly reduces fractures among older women, promising the best treatment yet for osteoporosis, a study has found.
The drug, Forteo, replaces a hormone that helps regulate calcium. A study reported in today's New England Journal of Medicine says it reduced fractures by 50 to 70 percent in women who took it during a clinical trial and boosted their bone density by about 10 percent.
Other osteoporosis drugs, such as Merck's Fosamax, Eli Lilly's Evista and estrogen, work by slowing bone loss. If approved, Forteo would be the first to actually encourage the body to build bone.
The drug was developed by Lilly, which also paid for the study. The National Osteoporosis Foundation and Tampa Bay-area physicians who treat the disease said it appears to be an exciting development, although questions remain.
"I think it's very significant. Unless there's some unknown side effect, I think it's going to be very important," said Dr. Joel Silverfield, a rheumatologist with St. Joseph's-Baptist Health Care in Tampa who treats women with osteoporosis and has helped investigate other treatments for it.
"It will be a new tool for us to add to our pretty good tool chest for osteoporosis," Silverfield said.
Many women can't take hormones, and Fosamax causes intestinal problems for many others, "so there's a pretty good niche for that drug," Silverfield said.
Bones are constantly being broken down and rebuilt by the body. As we age, our bones lose more than they gain, leading to reduced bone mineral density and making bones prone to breaks. This is osteoporosis, and it is most prevalent in women.
Osteoporosis affects some 10-million women, including 2.1-million in Florida. Spine and hip fractures are a leading cause of hospitalization for the elderly, and the osteoporosis foundation blames the disease for 1.5-million fractures a year.
Researchers have long thought the parathyroid hormone could help.
Parathyroids, tiny glands in the neck, secrete a hormone that helps regulate levels of calcium in the blood. Production of this hormone drops after menopause, and that drop is considered a key cause of osteoporosis.
Forteo (pronounced for-TAY-oh) is a synthetic version of key parts of that hormone.
"It's very, very exciting that we have taken this basic scientific knowledge of the parathyroid gland and its endocrinology and actually put it into a clinical application," said Dr. Sally Osborne, a St. Petersburg gynecologist and researcher.
"That's been in the works, and we've been getting ready as clinicians to take advantage of it."
The two-year trial was conducted at 99 sites in 17 countries, including the United States and Canada.
It included 1,637 post-menopausal women, with an average age of 69, who were diagnosed with osteoporosis and have had at least one fracture of the spine.
One-third received a placebo, and two-thirds received 20 micrograms or 40 micrograms of Forteo. All received daily supplements of calcium and vitamin D.
Women given the drug were 65 to 69 percent less likely to develop spinal fractures and were 54 percent less likely to suffer fractures elsewhere, such as the hip, ankle or wrist, the study said. Bone mineral density also increased 9 to 13 percent more than in the women on Vitamin D and calcium alone.
Side effects included dizziness and leg cramps in women who took the lower dose, and nausea or headache in women who took the higher dose. Lilly stopped the trial in 1998 after rats who had been on the drug long-term developed bone cancer, but it resumed the study after determining the findings in rats did not endanger humans in this case, the company said. Previous studies have found it is safe.
The drug appeared to work best after one to two years, and likely will be used in conjunction with current bone-conserving drugs, at least at first. It also must be injected, like insulin, and that may be unattractive to many women.
But the study failed to answer several key questions: How effective might it be in preventing osteoporosis, or in rebuilding bone in women with mild stages of the disease? How will it change the risk of fractures among women who haven't broken anything?
"Patients who have had fractures already are very different," Silverfield said. "Sometimes, if someone has something very bad, it's easier to show that (a treatment) works.
"The way, unfortunately, that many women find out they have (osteoporosis) is they break a bone. You want to diagnose it before, and still treat it."
National Osteoporosis Foundation Web site
The New England Journal of Medicine Web site