FDA Approves Arimidex For First-Line Treatment of Advanced Breast Cancer (dateline September 7, 2000)

The U.S. Food and Drug Administration (FDA) has recently approved the drug Arimidex (generic name, anastrozole) to help treat post-menopausal women with advanced breast cancer whose cancers are hormone receptor positive (or hormone receptor unknown). Physicians often examine hormone receptors in breast cancer cells at the time of biopsy or breast surgery to determine whether estrogen receptors (ER-positive) or progesterone receptors (PR-positive) are present. Patients whose cancers have ER or PR-positive receptors tend to have better prognoses than patients whose cancers do not have these receptors, since patients with hormone receptor positive cancers often respond better to chemotherapy or other drug treatments.

Nearly 11,000 women are diagnosed with advanced (metastatic) breast cancer each year. Metastatic breast cancer is cancer that has spread past the breast and axillary (underarm) lymph nodes to other regions of the body. Breast cancer commonly spreads first to the bone, although it can spread to any region of the body, including the lungs, liver, brain, ovaries, spinal cord, eye, and other areas. Extensive medical research in recent years has produced a variety of new treatment options for women with advanced breast cancer.

Arimidex was first approved by the FDA in January 1996 as a treatment option for post-menopausal women with advanced breast cancer who have not responded well to treatment with tamoxifen (brand name, Nolvadex). The FDA’s approval of Arimidex as a first-line treatment (a primary treatment option) comes after a large clinical trial called the North American Trial 030 showed that Arimidex may provide an advantage over tamoxifen in the ability to slow tumor progression in advanced breast cancer patients. Another clinical trial, called the European Trial 027, showed that patients with estrogen-receptor positive breast cancer patients benefited most from Arimidex.

A long-term study comparing Arimidex with tamoxifen in early stage breast cancer patients is currently underway. ATAC (Arimidex, Tamoxifen Alone or in Combination) is a clinical trial involving over 9,000 post-menopausal women from cancer centers worldwide. In addition to evaluating the safety of the two drugs, researchers will also investigate whether a combined treatment of Arimidex and tamoxifen may improve patient outcomes. Results of the ATAC study are expected in 2001.

Unlike tamoxifen, which interferes with the ability of cancer cells to use estrogen to grow and divide, Arimidex works by inhibiting the body’s conversion of certain steroid hormones (androgens) to estrogen by the enzyme aromatase. By decreasing the overall concentration of estrogen in the body, Arimidex may help reduce the spread of breast cancer in post-menopausal women.

Most post-menopausal women treated with Arimidex take one 1-mg tablet each day. Since Arimidex cannot distinguish between normal cells and cancer cells, side effects may occur. The most common side effects of Arimidex include a general feeling of weakness and a decreased energy level. Other side effects that have been reported with Arimidex include:

Headache
Nausea
Hot flashes
Mild diarrhea
Increased or decreased appetite
Sweating
Vaginal dryness
Temporary hair thinning

Not all women with advanced breast cancer are candidates for Arimidex therapy. Because Arimidex decreases the body’s overall level of estrogen, women at high risk of osteoporosis (a degenerative bone disease) may not be suited for Arimidex therapy. Post-menopausal women with advanced breast cancer are encouraged to discuss all treatment options with their physicians.

Additional Resources and References

The September 1, 2000 AstraZeneca press release, "FDA Approves Arimidex, A New First Line Treatment Option For Breast Cancer," is available at http://www.astrazeneca-us.com/news/article.asp?file=2000090101.asp
The medical study, "The Effects of Neoadjuvant Anastrozole (Arimidex) On Tumor Volume in Postmenopausal Women with Breast Cancer: A Randomized, Double-Blind, Single-Center Study," is published in the June 6, 2000 issue of Clinical Cancer Research. An abstract of the study is available at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db
=PubMed&list_uids=10873072&dopt=Abstract
The December 30, 1999 Imaginis.com report, "Arimidex May Be More Successful Than Tamoxifen in Post-Menopausal Breast Cancer Patients," is available at http://www.imaginis.com/breasthealth/news/news12.30.99b.asp
To learn more about Arimidex, please visit http://www.imaginis.com/breasthealth/bc_drugs.asp#Arimidex
AstraZeneca, the manufacturer of Arimidex, provides full prescribing information at http://www.astrazeneca-us.com/cgi-bin/az_pi.cgi?product=arimidex&country=
US&inframe=no
To learn more about tamoxifen, please visit http://www.imaginis.com/breasthealth/tamoxifen.asp

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