AZ receives FDA approval for Faslodex injection

The US FDA has granted approval to AstraZeneca's new breast cancer drug Faslodex (fulvestrant) Injection for the treatment of hormone receptor positive metastatic breast cancer in postmenopausal women for whom tamoxifen has proved ineffective. Faslodex is an oestrogen receptor antagonist without known agonist effects and the only oestrogen receptor antagonist to be proven effective after tamoxifen failure.

Faslodex is a hormonal therapy that works by binding, blocking and degrading the estrogen receptor, and does not cause the type of side effects commonly associated with cytotoxic chemotherapy. It is taken as a once-monthly intramuscular injection.

The FDA approval was based on data from two Phase III, randomised, multi-centre studies comparing Faslodex 250mg once monthly injection to daily 1mg oral Arimidex (anastrozole) tablets, the most commonly prescribed aromatase inhibitor. Objective response rate in a North American trial was 17% with Faslodex vs 17% with Arimidex, and in a European trial 20% vs 15%. The reported time to progression for Faslodex vs Arimidex 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.