Arimidex granted approval in US for early breast cancer

The US FDA has approved AstraZeneca's Arimidex (anastrozole) for the adjuvant treatment of early breast cancer in postmenopausal women. The approval is based on the groundbreaking results from the ATAC (Arimidex, Tamoxifen, Alone or in Combination) study - the world's largest ever breast cancer trial - which showed that Arimidex had significant efficacy and tolerability benefits tamoxifen in this setting.

The ATAC study demonstrated that there is a 17% relative risk reduction for breast cancer recurrence with Arimidex treatment compared with tamoxifen. Among women confirmed with hormone-sensitive tumours, the reduction in relative risk was even more striking, at 22%. Additionally, Arimidex was shown to reduce the likelihood of contralateral breast cancer. Compared with tamoxifen, which had already shown an almost 50% reduction in this area versus control, Arimidex reduces the risk by a further 58%.

Arimidex is already licensed worldwide for use in advanced disease where it has become the world's leading aromatase inhibitor with over 600,000 patient years experience. However, it is the only aromatase inhibitor to be approved for use in the adjuvant treatment of early breast cancer in postmenopausal women.

Arimidex has already been approved as an adjuvant treatment for postmenopausal women with early breast cancer in Belgium and Mexico and AZ also has a licence to promote this indication in Japan. Applications for approval for this application were submitted in Europe and other rest-of-world markets earlier this year.

Arimidex sales in 2001 were US$191m (€196m), a 22% increase over the previous year. AstraZeneca's Nolvadex (tamoxifen) accounted for $630m (€646m) in sales the same year. The early breast cancer market could be worth approximately $2.0bn (€2.1bn).