Fulvestrant for the Treatment of Advanced Breast Cancer in Postmenopausal Women: A Japanese Study

Abstract

Background: Fulvestrant (‘Faslodex’) is a new type of oestrogen receptor (ER) antagonist that down-regulates the ER and has no known agonist effects. Patients and Methods: In this open-label, Phase II trial, 30 postmenopausal Japanese women with hormone-sensitive advanced breast cancer, who had progressed on tamoxifen/toremifene following an initial response, received fulvestrant (250 mg; once-monthly intramuscular injection). Primary endpoints were objective tumour response rate (complete or partial response) and assessment of tolerability; secondary endpoints included clinical benefit (objective response, or stable disease ≥ 24 weeks), duration of response and pharmacokinetic analysis. Results: The objective response rate was 23.3% and 60.0% of patients experienced clinical benefit. Adverse events were generally mild; the most common were pharyngitis (26.7%), headache (23.3%) and nausea (20.0%). Pharmacokinetic data were similar to a Western study of postmenopausal patients. Conclusion: Fulvestrant 250 mg/month is effective and well-tolerated in Japanese patients who have relapsed after one prior endocrine treatment.