WILMINGTON, DelawareThe US Food and Drug Administration has granted
approval to AstraZeneca’s breast cancer drug Faslodex (fulvestrant) Injection
for treatment of hormone-receptor-positive metastatic breast cancer in
postmenopausal women with disease progression following antiestrogen therapy,
such as tamoxifen (Nolvadex). Faslodex is a selective estrogen-receptor
antagonist without known agonist effects.
Faslodex works by binding to, blocking, and degrading the estrogen receptor,
AstraZeneca said in a news release announcing the approval. It is given as a
monthly intramuscular injection, which may assist health care professionals in
monitoring compliance and may also make treatment more convenient for some
patients, the company said.
The FDA approval was based on data from two phase III, randomized
multicenter, studies (one in North America and one predominantly in Europe)
comparing Faslodex 250-mg once-monthly injection with daily 1 mg oral
administration of the aromatase inhibitor anastrozole (Arimidex).
The 851 women in the trials were postmenopausal with a variety of involved
sites, including liver and lung, and had been treated with one prior hormonal
therapy, in almost all cases, tamoxifen.
Objective response rates in the North American trial were 17% with Faslodex
vs 17% with anastrozole, and in the European trial 20% with Faslodex vs 15%
with anastrozole. The time to progression for Faslodex vs anastrozole was 5.5
months vs 3.5 months in the North American trial, and 5.5 months vs 5.2 months
in the European trial.