BODY'S natural bone builder proves effective against fractures

Wednesday, May 9th 2001, 12:00 am
By: News On 6

BOSTON (AP) _ A natural bone-building hormone appears to be the most effective treatment ever for osteoporosis, the brittle bone disease that afflicts millions of older Americans.

The manufacturer hopes the medicine, called Forteo (for-TAY-oh), will be available by prescription by the end of the year. If so, it is likely to be recommended for victims of moderate to severe osteoporosis, a condition blamed for more than 1.5 million fractures annually in the United States.

The drug is based on the parathyroid hormone, which is ordinarily secreted by tiny glands in the neck. When given to volunteers with osteoporosis, it doubles their normal rate of bone formation.

A study in Thursday's New England Journal of Medicine shows that it dramatically reduces the risk of broken bones. The risk of spinal fractures, a hallmark of osteoporosis, fell by two-thirds in women getting the medicine.

Other osteoporosis drugs on the market, such as Fosamax, work by slowing the body's loss of bone. Forteo is the only treatment that actually prompts the body the make new bone.

But unlike the other medicines, Forteo has a major drawback: It can be administered only by daily injections. Still, doctors say patients quickly master this process, which is similar to insulin injections, and no serious side effects were seen.

``It's the first demonstration of the concept that stimulating bone formation is going to be an effective way to treat osteoporosis in humans,'' said Dr. Robert M. Neer of Massachusetts General Hospital, the study's director.

The medicine, known generically as teriparatide, is being developed by Eli Lilly, which financed the study.

Dr. Felicia Cosman of Helen Hayes Hospital in West Haverstraw, N.Y., clinical director of the National Osteoporosis Foundation, estimated that 25 percent to 30 percent of osteoporosis patients might be considered for treatment with the new drug.

``It represents a lot of hope for the future for women with severe osteoporosis, especially those who are on the best drugs and still having fractures,'' she said.

The foundation estimates that 10 million Americans _ 80 percent of them female _ have osteoporosis. Broken vertebrae, hips and wrists are especially common.

The latest study was conducted on 1,637 postmenopausal women who had suffered at least one fracture because of osteoporosis. They were randomly assigned to take either 20 or 40 micrograms of the hormone or dummy shots. After 18 months of treatment, women taking the higher dose of drug had 13 percent more bone in their spines than did those on the placebo.

Forteo has not been compared directly to other drugs, so doctors cannot say for sure that it is truly better. However, the results of this and other studies with the new medicine are more impressive than those typically seen with other drugs. For instance, the researchers said the largest increase in bone seen with other drugs was 9 percent.

Forteo reduced the occurrence of new vertebral fractures by 65 percent or 69 percent, depending on whether women got the high or low dose. Neer said no other drug has reduced it by more than 40 percent to 50 percent.

The new drug reduced the risk of multiple spinal fractures by 77 percent or 86 percent, and it lowered the risk of fractures elsewhere in the body by just over half.

The study was stopped early because of a cancer scare resulting from other Lilly research in which scientists found that rats developed bone cancer when given high lifelong doses of the drug.

However, researchers eventually decided that the results do not suggest a higher cancer risk in people. Among other things, people with naturally high levels of the hormone as a result of overactive parathyroid glands are not especially prone to bone cancer, and none of the women in this or earlier studies of the hormone has developed the cancer.

The entire parathyroid hormone contains 84 amino acids. Forteo is a 34-amino acid portion of this. Experts believe it does the same job as the full hormone.