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Fulvestrant Adds Punch to Anastrozole for HR+ Breast Cancer
Major Finding: Median overall survival was 47.7 months among those randomized to combination anastrozole and fulvestrant therapy, compared with 41...
A regimen combining anastrozole with fulvestrant added 6 months to the lives of postmenopausal women with previously untreated, hormone receptor–positive metastatic breast cancer, according to clinical trial results published August 2 in the New England Journal of Medicine.
Overall survival increased significantly from a median of 41.3 months with anastrozole (Arimidex) alone to 47.7 months with anastrozole and fulvestrant (Faslodex) in the Southwest Oncology Group (SWOG) S0226 trial. The combination’s survival advantage prevailed with a hazard ratio for death of 0.81 despite crossover to single-agent fulvestrant by 41% of patients in the control group after disease progression.
Median progression-free survival, the trial’s primary end point, also showed a statistically significant improvement from 13.5 months to 15 months, Dr. Rita S. Mehta of the University of California, Irvine, Medical Center, and her associates report (N. Engl. J. Med. 2012; 367: 435-4 [doi: 10.1056/NEJMoa1201622]).
The study randomized 707 patients, of whom 694 were included in the intention-to-treat analysis. All participants received 1 mg of anastrozole orally each day. Those assigned to the experimental arm also received a 500 mg loading dose of fulvestrant administered intramuscularly on day 1, followed by 250 mg on days 14 and 28 of 28-day cycles. The fulvestrant dose is lower than the 500-mg dose approved by the Food and Drug Administration, and the protocol was amended on Feb. 2, 2011 to allow patients in both study arms to receive the higher dose upon progression.*
Although three deaths may have been associated with the combination treatment, the investigators report that grade 3-5 adverse events were not significantly different between the two arms of the trial.
The study was funded by the National Cancer Institute and AstraZeneca. Disclosures for the individual authors are posted at www.nejm.com.
The NEJM report expands on results presented at the San Antonio Breast Cancer Symposium in December 2012. Dr. Hope Rugo and Dr. William Gradishar, associate editors of The Oncology Report, a publication of Elsevier, discussed the regimen at that meeting in the accompanying video.
*Correction, 8/1/2012: An earlier version of this story misstated the date of FDA approval for the 500-mg dose of fulvestrant.