SAN ANTONIO — An experimental drug may offer another treatment option for certain women with advanced breast cancer, researchers say.
Estrogen fuels the growth of about half of breast cancers. A standard therapy is tamoxifen, which prevents estrogen from linking up to cells' estrogen receptors. But over several years, tamoxifen can lose its effectiveness, allowing cancer to grow again. So scientists are hunting alternatives.
Women with tamoxifen-resistant advanced breast cancer were either injected with the experimental drug Faslodex or given another tamoxifen alternative called Arimidex that recently was approved by the Food and Drug Administration.
Neither drug is a cure. But Faslodex proved about as effective as Arimidex, concluded studies funded by Faslodex manufacturer AstraZeneca. In a study of 400 women, cancer began progressing after 5.4 months of Faslodex treatment, compared with 3.4 months of Arimidex treatment, researchers recently told the 23rd annual San Antonio Breast Cancer Symposium.
"That extra time can be extremely meaningful to women with advanced breast cancer and their families," said lead researcher Dr. Kent Osborne of the Baylor College of Medicine in Houston.
Faslodex works differently than other drugs, by degrading the estrogen receptor. Tamoxifen, in contrast, blocks the receptor, and Arimidex reduces estrogen levels.
"If it is free of side effects, and if it's as effective, it will take over. Oncologists in general are willing to take on a new drug because it [breast cancer] is such a serious disease," said Dr. Herman Kattlove, a medical oncologist and medical editor for the American Cancer Society.
AstraZeneca plans next year to request FDA approval to sell Faslodex.