ORLANDOCompared with the aromatase inhibitor anastrozole(Drug information on anastrozole) (Arimi-dex), mean duration of response is significantly greater with fulvestrant (Faslo-dex) in postmenopausal women with advanced breast cancer who have progressed on prior endocrine therapy. For other key endpoints, fulvestrant was at least as effective as anastrozole, according to a poster presentation at the 38th Annual Meeting of the American Society of Clinical Oncology (abstract 160).
Fulvestrant is an estrogen-receptor downregulator with no known agonist activity, said Leroy M. Parker, MD, associate clinical professor of medicine, Harvard Medical School, Dana-Farber Cancer Institute.
He reported on combined results from two randomized phase III multicenter trials enrolling 851 patients: an open-label trial from centers in Europe, South Africa, Australia enrolling 451 patients and a double-blind North America trial enrolling 400 patients. In each trial, patients received either monthly intramuscular injections of 250 mg fulvestrant or once-daily oral 1 mg anastrozole.
Included women were postmenopausal and hormone sensitive, and had received no more than one prior endocrine treatment (including prior fulvestrant or aromatase inhibitors). They had objective evidence of recurrence of disease progression. Mean age was 63.4 years in both groups.
Previously presented findings at follow-up of 15.1 months had shown median time to progression, the primary endpoint, to be 5.5 months for fulvestrant and 4.1 months for anastrozole, with objective response rates of 19.2% and 16.5%, respectively. Dr. Parker presented updated results with a median of 22.1 months of follow-up.
[Separate reports on both studies with median follow-up of 16.8 months for the US trial and 14.4 months for the European trial were recently published in the August 15, 2002, issue of the Journal of Clinical Oncology.]