Survival update from a phase II trial of fulvestrant ('Faslodex®') in tamoxifen-resistant breast cancer patients

Fulvestrant ('Faslodex®'), a novel Estrogen Receptor Downregulator has recently been shown to be at least as effective as anastrozole ('Arimidex®') in postmenopausal women with advanced breast cancer progressing on prior endocrine therapy. Here we report the results of a survival update from a phase 11 trial that included patients who refused or were unfit for surgery for primary breast cancer, and patients with locally advanced or metastatic breast cancer. All had hormone-sensitive cancer with tamoxifen as prior therapy. Methods: Nineteen such patients received fulvestrant with an objective response/stable disease (OR/SD) rate of 69% at 6 months. The median duration of response in these patients was 26 months. In a matched group of 57 historical control patients (i.e. 1:3) who had received megestrol acetate for the same indication, the median duration of response was 14 months. Results: At the time of carrying out the survival update, 80% of fulvestrant-treated patients had died, and the median survival was 54 months. In the matched group of megestrol acetate-treated patients, where again approximately 80% of the patients had died, the median survival was 30 months. This suggests that fulvestrant can produce a longer duration of response and possibly a survival advantage when compared indirectly with megestrol acetate as second-line endocrine therapy. Conclusion: The results of this phase II study show a highly encouraging median survival for fulvestrant-treated patients of 54 months. The survival data from the fulvestrant vs. anastrozole, and the initial findings of the fulvestrant vs. tamoxifen trials are awaited with interest.