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For many years, tamoxifen has been the 'gold standard' amongst anti-oestrogen therapies for breast cancer. However, the selective aromatase inhibitors (AIs), anastrozole, letrozole and exemestane, have demonstrated advantages over tamoxifen as first-line treatments for advanced disease. Anastrozole is also more effective as an adjuvant treatment in early, operable breast cancer and is being increasingly used in the adjuvant setting. Generally, the selective oestrogen receptor modulators (SERMs), such as toremifene, droloxifene, idoxifene, raloxifene, and arzoxifene, show minimal activity in tamoxifen-resistant disease and show no superiority over tamoxifen as first-line treatments. In addition to these agents, other treatment options for advanced disease include high-dose oestrogens and progestins. Response rates for high-dose oestrogens and tamoxifen are similar, but the use of oestrogens is limited by their toxicity profile. Consequently, there is a need for new endocrine treatment options for breast cancer, particularly for use in disease that is resistant to tamoxifen or AIs. Fulvestrant ('Faslodex') is a new type of steroidal oestrogen receptor (ER) antagonist that downregulates cellular levels of the ER and progesterone receptor and has no agonist activity. This paper reviews the key efficacy and tolerability data for fulvestrant in postmenopausal women in the context of other endocrine therapies and explores the potential role of fulvestrant within the sequencing of endocrine therapies for advanced breast cancer.

Fulvestrant is a new type of oestrogen receptor (ER) antagonist with no agonist activity and a novel pharmacological profile. Fulvestrant has been shown to significantly reduce cellular levels of the ER and progesterone receptor in both preclinical studies and in clinical trials of postmenopausal women with primary breast cancer. This paper reviews the pharmacokinetics and metabolism of fulvestrant, which support the rationale for drug delivery as a single, once-monthly intramuscular injection, and show that this agent has minimal potential to be the subject, or cause, of significant cytochrome p450-mediated drug interactions.

Fulvestrant ('Faslodex') is a new type of endocrine treatment--an oestrogen receptor (ER) antagonist that downregulates the ER and has no agonist effects. Early efficacy data from phase I/II trials have demonstrated fulvestrant to be effective and well tolerated. Two randomised phase III trials have compared the efficacy of fulvestrant and the aromatase inhibitor, anastrozole, in postmenopausal women with advanced breast cancer progressing on prior endocrine therapy. Fulvestrant (intramuscular injection 250 mg month(-1)) was found to be at least as effective as anastrozole (orally 1 mg day(-1)) for time to progression (5.5 vs 4.1 months, respectively (hazard ratio (HR): 0.95; 95.14% confidence interval (CI), 0.82-1.10; P=0.48)) and objective response 19.2 vs 16.5%, respectively; treatment difference 2.75%; 95.14% CI, -2.27 to 9.05%; P=0.31). More recently, fulvestrant has also been shown to be noninferior to anastrozole in terms of overall survival, with median time to death being 26.4 months in fulvestrant-treated patients and 24.2 months in those treated with anastrozole (HR: 0.97; 95% CI, 0.78-1.21; P=0.82). In a further randomised phase III trial, fulvestrant was compared with tamoxifen as first-line therapy for advanced disease in postmenopausal women. In the overall population, efficacy differences favoured tamoxifen and noninferiority of fulvestrant could not be ruled out. In the prospectively defined subset of patients with ER-positive and/or progesterone receptor-positive disease, there was no statistically significant difference between fulvestrant and tamoxifen. This paper reviews the efficacy and tolerability results from these trials.

Purpose: To compare the efficacy and tolerability of fulvestrant (formerly ICI 182,780) and anastrozole in postmenopausal women with advanced breast cancer progressing after prior endocrine treatment., Patients and Methods: Patients (n = 451) with advanced breast cancer were randomized to receive fulvestrant 250 mg as a once-monthly (one x 5 mL) intramuscular injection or an oral dose of anastrozole 1 mg in this open, parallel-group, multicenter trial. The primary end point was time to progression (TTP). Secondary end points included objective response (OR) rates, defined as complete response (CR) or partial response (PR), duration of response (DOR), and tolerability., Results: Patients were followed for a median period of 14.4 months. In terms of TTP, fulvestrant was as effective as anastrozole (hazard ratio, 0.98; confidence interval [CI], 0.80 to 1.21; P =.84). Median TTP was 5.5 months for fulvestrant and 5.1 months for anastrozole. OR rates showed a numerical advantage for fulvestrant (20.7%) over anastrozole (15.7%) (odds ratio, 1.38; CI, 0.84 to 2.29; P =.20). Clinical benefit rates (CR + PR + stable disease > or = 24 weeks) were 44.6% for fulvestrant and 45.0% for anastrozole. Median DOR was 14.3 months for fulvestrant and 14.0 months for anastrozole. Both treatments were well tolerated, with 3.2% and 1.3% of fulvestrant- and anastrozole-treated patients, respectively, withdrawn from treatment because of an adverse event., Conclusion: Fulvestrant was as effective as anastrozole. These data confirm that fulvestrant is an additional, effective, and well-tolerated treatment for advanced breast cancer in postmenopausal women whose disease progressed on prior endocrine therapy.

Fulvestrant (‘Faslodex’) is a new type of endocrine treatment - an oestrogen receptor (ER) antagonist that downregulates the ER and has no agonist effects. Early efficacy data from phase I/II trials have demonstrated fulvestrant to be effective and well tolerated. Two randomised phase III trials have compared the efficacy of fulvestrant and the aromatase inhibitor, anastrozole, in postmenopausal women with advanced breast cancer progressing on prior endocrine therapy. Fulvestrant (intramuscular injection 250?mg?month-1) was found to be at least as effective as anastrozole (orally 1?mg?day-1) for time to progression (5.5 vs 4.1 months, respectively (hazard ratio (HR): 0.95; 95.14% confidence interval (CI), 0.82-1.10; P=0.48)) and objective response 19.2 vs 16.5%, respectively; treatment difference 2.75%; 95.14% CI, -2.27 to 9.05%; P=0.31). More recently, fulvestrant has also been shown to be noninferior to anastrozole in terms of overall survival, with median time to death being 26.4 months in fulvestrant-treated patients and 24.2 months in those treated with anastrozole (HR: 0.97; 95% CI, 0.78-1.21; P=0.82). In a further randomised phase III trial, fulvestrant was compared with tamoxifen as first-line therapy for advanced disease in postmenopausal women. In the overall population, efficacy differences favoured tamoxifen and noninferiority of fulvestrant could not be ruled out. In the prospectively defined subset of patients with ER-positive and/or progesterone receptor-positive disease, there was no statistically significant difference between fulvestrant and tamoxifen. This paper reviews the efficacy and tolerability results from these trials.British Journal of Cancer (2004) 90(Suppl 1), S11-S14. doi:10.1038/sj.bjc.6601631 www.bjcancer.com [ABSTRACT FROM AUTHOR]

Fulvestrant is a new type of oestrogen receptor (ER) antagonist with no agonist activity and a novel pharmacological profile. Fulvestrant has been shown to significantly reduce cellular levels of the ER and progesterone receptor in both preclinical studies and in clinical trials of postmenopausal women with primary breast cancer. This paper reviews the pharmacokinetics and metabolism of fulvestrant, which support the rationale for drug delivery as a single, once-monthly intramuscular injection, and show that this agent has minimal potential to be the subject, or cause, of significant cytochrome p450-mediated drug interactions.British Journal of Cancer (2004) 90(Suppl 1), S7-S10. doi:10.1038/sj.bjc.6601630 www.bjcancer.com [ABSTRACT FROM AUTHOR]