WILMINGTON, Delaware—AstraZeneca’s nonsteroidal aromatase inhibitor Arimidex (anastrozole) has received FDA approval for the adjuvant treatment of hormone-receptor-positive early-stage breast cancer in postmenopausal women. The agent was previously approved as first-line treatment of hormone-receptor-positive advanced breast cancer in postmenopausal women and as second-line treatment for those whose disease has progressed following treatment with tamoxifen(Drug information on tamoxifen) (Nolvadex).
The effectiveness of Arimidex in the adjuvant setting was based on analysis of data at a median duration of treatment of 31 months, the company said in a news release. Further follow-up will be required to determine long-term outcomes. The approval is based on research from the ATAC (Arimidex, Tamoxifen, Alone or in Combination) study, the world’s largest breast cancer treatment study involving more than 9,300 postmenopausal women in 21 countries.
Trial results show that 183 of 3,125 women in the Arimidex group had a relapse of their breast cancer or died, compared with 379 of 3,116 women in the tamoxifen (Nolvadex) group (hazard ratio 0.83; P = .013), representing a statistically significant 17% relative reduction in the risk of disease recurrence with Arimidex. The relative reduction in the risk of recurrence was 22% in women with confirmed hormone-sensitive tumors with Arimidex, compared with tamoxifen (hazard ratio 0.78).
Venous thromboembolic events were reported in 4% of tamoxifen patients vs 2% of Arimidex patients. Endometrial cancer occurred at a rate of 0.5% of tamoxifen patients vs 0.1% of Arimidex patients.
