FDA Approves Arimidex® for Treating Early Breast Cancer

Arimidex®, has been approved by the U.S. Food and Drug Administration for the treatment of early breast cancer in postmenopausal women.

The approval is based on results from the Arimmidex, Tamoxifen, Alone or in Combination (ATAC) study, the world's largest breast cancer trial to date, which showed significant effectiveness and tolerability benefits of Arimidex over tamoxifen in this use.

Arimidex is the first aromatase inhibitor to be approved for use in the treatment of this patient population. The drug is already used worldwide in treating advanced breast cancer.

"Since first seeing the strength of the ATAC results, we have worked quickly to seek extended licenses for Arimidex, and bring the proven benefits of the drug to the many postmenopausal women newly diagnosed with early stage breast cancer," said Bernie Tyrrell, Vice President, Marketing, AstraZeneca Oncology, makers of the drug.

The ATAC study showed that Arimidex is more effective than tamoxifen in terms of disease free survival. Also, Arimidex reduced the likelihood of the cancer spreading to the opposite breast. Compared with tamoxifen, which gives about a 50 percent reduction, Arimidex reduces the risk by a further 58 percent.

Arimidex lacks some of tamoxifen's side effects, such as an increased risk of uterine cancer and blood clots. However, tamoxifen can be used by women who have not yet gone through menopause, while Arimidex cannot.

Tamoxifen has effects similar to estrogen and while Arimidex does not. Women with osteoporosis may experience more bone loss while taking Arimidex compared to tamoxifen. Also, Arimidex is twice as expensive as tamoxifen.

Other sources: AstraZeneca, FDA