WILMINGTON, DelawareAstraZeneca’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 (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
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.