A new drug to fight osteoporosis, the bone condition associated with aging and debilitating fractures, reduces the risk of fractures and the risk of some breast cancers, heart disease and stroke, according to a new study.

But, like other anti-osteoporosis drugs already on the market, the drug-called lasofoxifene-also boosts the risk of blood clots, the researchers found. Lasofoxifene (the drug's proposed brand name is Fablyn) is not yet approved by the US Food and Drug Administration.

About The Drug

The new drug is in a class of medications known as selective estrogen-receptor modulators (SERM), which act like estrogen in some tissues but anti-estrogen in others. "They act like estrogens when binding to bone cells and don't act like estrogen in the breast (thus not 'feeding any cancers of the breast]," said lead study author Steven R. Cummings, MD.

Another SERM, already on the market, is raloxifene Evista).

The Study

For the study, Dr. Cummings, professor emeritus and former director of the San Francisco Coordinating Center at the University of California, San Francisco, and his team assigned 8,556 women with osteoporosis, ages 59 to 80, to take a daily dose of the drug (either 0.25 milligrams (mgl or 05 mg a day) or a placebo for five years. All had a bone mineral density T score of -2.5, which is considered osteoporosis.

In the study, the researchers found that lasofoxifene "reduces the risk of all fractures (spinal and elsewhere), breast cancer, heart disease and stroke," said Dr. Cummings. "Breast cancer by more than half, nonspinal fractures by about a quarter, which is similar to what other drugs have done, stroke and heart disease by a quarter to a third."

The results he cites are all for the higher dose, 05 mg a day, when compared with placebo. The higher dose worked better, they found, and is the dose planned for clinical use.

Side Effects

When Dr. Cummings looked at adverse events during the follow-up, he found deaths were comparable in the high-dose and placebo group (73 and 65), but more deaths occurred in the low-dose group (90) from any cause.

More women taking the drug developed lung cancer, too—28 compared with four in the placebo group. Dr. Cummings said that may be related to chance. Further studies should help explain this link.

Blood clot risk more than doubled on the drug, they found, a risk similar to what is found with estrogen and other SERMs, although the absolute risk was still small.

The study was published in The New England Journal of Medicine.

Implications For The Future

Overall, lasofoxifene looks good, according to Dr. Cummings.

But Carolyn Becker, MD, associate professor or medicine at Harvard Medical School, is taking a wait-and-see approach. "It may turn out to be a dynamite drug, but it's not anything I would rush in to use as a clinician," she said. "There are too many unknowns."

"The big news for osteoporosis is that lasofoxifene also prevents the fractures that cause most of the disability," Dr. Cummings said, referring to nonspinal fractures such as hip, upper arm and pelvis.

But Dr. Becker pointed out that this effect did not kick in until five years, and the absolute risk reductions were small.


Women with osteoporosis should first consider drugs known as bisphosphonates (Fosamax and others), Dr. Cummings said, turning to SERM drugs if they are considered at higher risk.

Dr. Cummings has reported receiving consulting fees from pharmaceutical companies including Pfizer, which is developing Fablyn. Dr. Becker reports no such consulting fees.

Beat Osteoporosis Now!

Osteoporosis patients received one annual dose of intravenous zoledronic acid (Reclast).. daily injections of teriparatide (Forteo)... or both.

After one year: Lumbar spine bone mass increased by 751% in the combination group, 7.05% in the teriparatide group and 4.37% in the zoledronic acid group.

Best: Discuss osteoporosis treatment options with your doctor-the drugs can have unwanted side effects.

Pricey Osteoporosis Drug No Better than Cheaper Generics

The medicine ibandronate (Boniva) can be taken monthly. Other cheaper drugs in the same class, called bisphosphonates, must be taken weekly or daily. But they all are about equally effective at preventing bone fractures and Boniva costs 10 times as much as alendronate (Fosamax). Ask your doctor to consider the price when prescribing an osteoporosis medication for you.

Want to Keep Reading?

Continue reading with a Health Confidential membership.

Sign up now Already have an account? Sign in