The sNDA is based upon the results of the ATAC (Arimidex, Tamoxifen, Alone or in Combination) study of over 9,300 women, which showed that Arimidex is significantly more effective and has important tolerability benefits compared with the current gold standard, tamoxifen, as an adjuvant treatment in postmenopausal women with early breast cancer.

Arimidex sales in 2001 were $191 million, a 22 per cent increase over the previous year. AstraZeneca’s Nolvadex (tamoxifen) accounted for $630 million in sales the same year. The early breast cancer market could be worth approximately $2 billion. Arimidex sales in the US were $61 million.

“AstraZeneca is committed to constantly expanding the treatment options breast cancer patients have at their disposal to fight this disease,” said Gerard T. Kennealey, M.D., Vice President of Clinical Research, Oncology, for AstraZeneca. “The FDA’s granting of Priority Review Status for Arimidex as an early breast cancer treatment is an important milestone in the history of breast cancer treatment.”

After an average of 33 month’s follow-up, Arimidex monotherapy was found to be significantly more effective in preventing relapse than tamoxifen, with a 17 per cent reduction in risk of breast cancer recurring with Arimidex treatment compared with tamoxifen.

Arimidex was also found to have many important tolerability advantages over tamoxifen. Arimidex was associated with significantly fewer reports of endometrial cancer when compared with tamoxifen. This finding was supported by a significantly lower incidence of vaginal bleeding and vaginal discharge among Arimidex-treated patients compared to those taking tamoxifen.

Another known risk associated with tamoxifen is thromboembolic events. In the ATAC trial, both the overall incidence of thromboembolic events and that of deep vein thromboses were significantly reduced in the Arimidex group. Important from the patient’s perspective, the incidence of hot flushes and weight gain were also significantly reduced. However, as expected, women taking tamoxifen did have a lower risk of experiencing musculo-skeletal disorders or the types of fractures common in this age group compared with those taking Arimidex.

AstraZeneca is a major international healthcare business engaged in the research, development, manufacture and marketing of ethical (prescription) pharmaceuticals and the supply of healthcare services. It is one of the top five pharmaceutical companies in the world with healthcare sales of over $16.4 billion and leading positions in sales of oncology, gastroenterology, anaesthesia (including pain management), cardiovascular, central nervous system (CNS) and respiratory products.