Faslodex (chemical name: fulvestrant) is an estrogen receptor downregulator (ERD), a type of hormonal therapy. Faslodex blocks the effect of estrogen on breast tissue by sitting in the estrogen receptor in breast cells.
Right now, Faslodex is approved by the U.S. Food and Drug Administration (FDA) to treat postmenopausal women diagnosed with metastatic hormone-receptor-positive breast cancer that has stopped responding to other hormonal therapy medicines.
Faslodex is a liquid given as an injection into a muscle.
Arimidex (chemical name: anastrozole) is an aromatase inhibitor, another type of hormonal therapy. Aromatase inhibitors work by blocking the enzyme aromatase, which turns androgen hormones into small amounts of estrogen in the body. This means that less estrogen is available to stimulate the growth of hormone-receptor-positive breast cancer cells.
Aromatase inhibitors can't stop the ovaries from making estrogen, so aromatase inhibitors only work in postmenopausal women.
Arimidex is approved by the FDA to treat postmenopausal women diagnosed with hormone-receptor-positive breast cancer that is early-stage, advanced-stage, or metastatic.
Arimidex is a pill taken by mouth.
Metastatic breast cancer is breast cancer that has spread to parts of the body away from the breast, such as the bones or liver.
A study has found that using Faslodex as the first treatment for hormone-receptor-positive, advanced-stage breast cancer offers better survival than using Arimidex as the first treatment.
The research was presented at the 2014 San Antonio Breast Cancer Symposium.
Doctors are always trying to figure out which medicines best treat different types of breast cancer. While Faslodex isn’t currently approved to be used as the first medicine to treat advanced-stage disease, the researchers thought it might be a good treatment and decided to compare it to the current standard treatment, Arimidex.
In the study, called the FIRST (Fulvestrant First-Line) trial, 205 women diagnosed with advanced-stage, hormone-receptor-positive breast cancer were assigned to have one of two treatments as the first treatment for advanced-stage disease:
- 500 milligrams of Faslodex per month, plus an additional 500 milligrams on day 14 of the first month (102 women)
- 1 milligram per day of Arimidex (103 women)
The study started in 2006. The women ranged in age from 40 to 89 and were being treated at 62 centers in nine countries.
As of July 2014, the researchers had information on 170 of the women.
The researchers found that the women who were treated with Faslodex lived longer than the women treated with Arimidex:
- Women who got Faslodex lived about 4.5 years.
- Women who got Arimidex lived about 4 years.
The researchers also found that women who were treated with Faslodex were 30% less likely to die from breast cancer than women who were treated with Arimidex.
“We found fulvestrant to be significantly better for women with advanced breast cancer than… [Arimidex], which has been the most potent endocrine therapy thus far in the first-line setting for advanced disease,” said John Robertson, M.D., professor of surgery at Graduate Entry Medical School at the University of Nottingham.
While these results are very promising, they are early results. More research needs to be done to confirm that Faslodex is the best first treatment for advanced-stage, hormone-receptor-positive breast cancer. To that end, the researchers have already started the phase III FALCON (A Global Study to Compare the Effects of Fulvestrant and Arimidex in a Subset of Patients with Breast Cancer) trial. The FALCON study will be very large and will provide evidence that will allow the FDA to make a decision on whether Faslodex should be approved as a first treatment for advanced-stage, hormone-receptor-positive breast cancer.
If you’ve been diagnosed with advanced-stage, hormone-receptor-positive breast cancer, you and your doctor will consider a number of treatment options, including hormonal therapy and chemotherapy. If you haven’t been treated with hormonal therapy for advanced-stage disease yet, you might want to talk to your doctor about this study and whether Faslodex might be a good first treatment choice for you, depending on your unique situation. You also may want to ask your doctor about the FALCON trial if you’re interested in a being part of a clinical trial.
Together, you and your doctor will decide on a treatment plan that’s best for you.
Read more news from the 2014 San Antonio Breast Cancer Symposium:
- Aromasin Plus Ovarian Suppression Reduces Recurrence Risk Better Than Tamoxifen Plus Ovarian Suppression in Premenopausal Women Who’ve Received Chemotherapy (with video)
- Low-Fat Diet and Weight Loss Improves Survival in Some Women
- Male Breast Cancer Is Different in Terms of Biology and Outcomes
- Abraxane Offers More Benefits Than Taxol When Given Before Surgery to Treat Early-Stage Disease
- Tamoxifen’s Benefits Long-Lasting for High-Risk Women
- Oncotype DX DCIS Test Helps Predict Risk of Recurrence
- High Levels of Immune Cells in HER2-Positive Cancers May Mean Tumors Need Only Chemotherapy