June 2, 2008

Bone Saving Drug May Prevent Breast Cancer Recurrence

In the first large study to affirm wider cancer-fighting applications for Zometa and other bone-building drugs called bisphosphonates, new research has found that Zometa, a bone loss prevention drug used by women undergoing breast cancer treatment, substantially reduced the risk of breast cancer recurrence.  

The study, led by Dr. Michael Gnant of the Medical University of Vienna, was  reported Saturday at an American Society of Clinical Oncology conference in Chicago, and has given doctors optimism about a potentially new way to fight the disease.    

The research involved 1,800 pre-menopausal women who were receiving hormone treatments for early-stage breast cancer, and found that Zometa reduced the chance of recurrence in their bones, or anywhere else, by one-third.

"This is an important finding. It may well change practice," said Dr. Claudine Isaacs, director of the clinical breast cancer program at Georgetown University's Lombardi Cancer Center, in an interview with the Associated Press.

Should a second, ongoing study confirm these benefits, experts expect that Zometa will also be tested with other cancers that tend to metastasize to bones, such as kidney or prostate cancer.

"Hugely important is whether this has to do with the fact that it just makes the bone hostile, somehow, to metastasis or if there is a more global anti-metastasis effect," said Dr. Nancy Davidson of Johns Hopkins University, the oncology group's president.

"Either of those would be good and would teach us a lot about what to do next."

Breast cancer is the most common cancer in women, and approximately184,450 cases and 40,930 deaths are expected from the disease in the United States this year.   Three-quarters of breast cancer cases occur in women after menopause. And while Zometa may help them as well, it hasn't been tested yet in women of that age group.

Standard breast cancer treatments include surgery, chemotherapy, radiation and hormone-blocking drugs if the tumors are fueled by estrogen or progesterone, like those in the study.

But the hormone-blocking treatments often weaken bones, so bisphosphonates like the osteoporosis pill Fosamax are increasingly used to treat this side effect.    However, using them to treat the breast cancer itself is a very different approach.

Gnant's is the first to test Zometa in a large group of breast cancer patients, although previous studies conducted in laboratory environments suggested it would work.

All the study participants had surgery to remove their tumors and were taking the hormone-blocking drugs goserelin plus either tamoxifen or anastrozole, which made the women menopausal.  Half also were given Zometa infusions every six months.

The women were then treated for three years and studied for two additional years.   By then, only 6 percent of those who took Zometa had suffered a relapse or died, compared with 9 percent of those didn't, representing a 36 percent reduction in risk.

Sixteen of the women who took Zometa died, versus 26 of the others.  And although the difference could be explained by chance alone, doctors hope the encouraging trend will translate to better survival as the participants are monitored further out in time.

Side effects, such as fever and bone and joint pain, were observed more often in women taking Zometa, but there were no significant differences in serious side effects.   And while two percent developed a rapid heartbeat, only three were hospitalized, two who were Zometa and one who was not.

Zometa's maker, Swiss-based Novartis, along with Britain's AstraZeneca PLC, the maker of Arimidex, sponsored the study.  Gnant consults for both companies as well as several other breast cancer drugmakers.

With doctor fees for the infusion, a Zometa treatment can run more than $1,200. The other large study is testing it in 3,360 women, both pre- and postmenopausal, with cancer that has spread but not extensively.

Researchers emphasize that the results so far only apply to women made menopausal by hormone-blocking treatments, not those who develop breast cancer after natural menopause.

"Using Zometa to prevent breast cancer recurrence should be confined to those who develop breast cancer before menopause," Dr. Eric Winer of Dana-Farber Cancer Center in Boston told the Associated Press.

The study's positive results show that "this is a treatment that doctors should talk to a patient about," Winer said.

In other news at the conference, women with advanced breast cancers taking Avastin plus Taxotere were slightly less likely to have their cancers progress than those taking Taxotere alone.   But the drug's side effects, such as high blood pressure, were observed more in those taking both drugs.   Taxotere treatment is more frequently prescribed in Europe and Asia, whereas Taxol is more common in the United States.

The study involved 736 women, 44 percent of those who were given only Taxotere saw their tumors shrink, compared with 55 percent of those who also took a lower dose of Avastin and 63 percent of those given a higher dose.

Avastin, marketed by California-based Genentech and Swiss-based Roche Holding AG, received federal approval for breast cancer recently, despite recommendations of outside advisers.  The approval was based on cancer progression, rather than overall survival, since the study's duration was too short to measure differences in survival.


Image Caption: Novartis AG headquarters in Basel, Switzerland


On the Net:

Medical University of Vienna

American Society of Clinical Oncology