Data Show Survival Benefit For Arimidex™ In Early Breast Cancer

According to this new analysis of data, by replacing tamoxifen with ‘Arimidex’, postmenopausal women being treated for early breast cancer may almost halve the likelihood of their disease returning and reduce their risk of dying by nearly a third.

“For the first time, an aromatase inhibitor has shown a survival advantage over tamoxifen in early breast cancer. These studies, along with others such as the ATAC trial, confirm that tamoxifen is no longer the best option we can offer our patients. Women who have taken two years of tamoxifen should be switched to anastrozole at the earliest opportunity to give them the best chance of surviving their disease,” commented Professor Walter Jonat of University of Kiel, Germany, the key investigator who presented the new data at the SABCS.

Three key international trials [ABCSG - Austrian Breast & Colorectal Cancer Study Group 8 (n = 2262), ARNO - ‘Arimidex’-‘Nolvadex’ 95 (n = 962), and ITA – Italian Tamoxifen Anastrozole (n = 448)] were similarly designed to assess, in women already being treated with tamoxifen, whether or not replacing tamoxifen therapy with ‘Arimidex’ after 2-3 years was more effective than remaining on tamoxifen for the full five year treatment period. Professor Jonat presented a meta-analysis of these three trials at SABCS today. The data showed at a median follow-up of 30 months, patients who started taking ’Arimidex’, rather than remaining on tamoxifen, experienced a:

• 29 per cent improvement in overall survival (HR 0.71; 95 percent CI 0.52 - 0.98; p=0.0377)
• 45 per cent improvement in event-free survival (HR 0.55; 95 percent CI 0.42 - 0.71; p<0.0001)
• 39 per cent improvement in distant recurrence-free survival (HR 0.61; 95 percent CI 0.45 - 0.83; p=0.0015) (Event-free survival: any disease recurrence – local, contralateral or distant; Distant recurrence free survival: distant recurrence only)

These data now confirm that replacing tamoxifen with ‘Arimidex’ can significantly reduce recurrence, prevent metastatic spread and ultimately save the lives of many women with early breast cancer.

Recent evidence and opinion have shown that women newly diagnosed with hormone-sensitive early breast cancer should be started on ‘Arimidex’ as the initial hormonal treatment after surgery. In the landmark Arimidex, Tamoxifen, Alone or in Combination (ATAC) Trial, women taking ‘Arimidex’ for the full five year treatment period had a significantly reduced risk of disease recurrence (including distant disease recurrence and contralateral breast cancer), compared with tamoxifen, especially during the first three years following surgery, when this risk is greatest. Additionally, these women suffered far fewer serious side effects, including an increased risk of endometrial cancer, thromboembolic events and ischaemic cerebrovascular events, than those who were started on tamoxifen. Although ’Arimidex’, like all AIs increases the risk of bone fracture compared with tamoxifen, it is possible to predict which women may be most at risk of fracture and manage them accordingly. This is not the case with the more serious side effects associated with tamoxifen.

“The ATAC trial has confirmed that starting treatment with anastrozole at the earliest opportunity after surgery, and giving it for the full five years of treatment, is more effective than tamoxifen for the prevention of disease recurrence. This would suggest that the best place to use anastrozole is right from the start. These new data are important news for women currently taking tamoxifen who can still gain from the significant benefits of anastrozole by switching at two years.” commented Prof Jeffrey Tobias of the University College London Hospitals, London, United Kingdom.

Arimidex is currently indicated for adjuvant treatment of early breast cancer in 81 markets based on superiority over tamoxifen in the ATAC trial. Arimidex has a broad licence for the US, Japan and a number of European markets. In June 2005 the Company announced that Arimidex had been granted a new indication – adjuvant treatment of post-menopausal women with hormone receptor positive early invasive breast cancer – from the Medicines and Healthcare Products Regulatory Agency in the UK, leading to further approvals in five other European countries (Austria, Germany, Italy, Portugal and Spain) under the Mutual Recognition Variation Procedure. For the nine months of 2005, Arimidex worldwide sales reached $856 million.

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Notes to Editors: · The current approved indication for Arimidex varies in different countries and these data may not be specifically within the licence for all markets. · In the UK, 'Arimidex' (anastrozole) is licensed for the adjuvant treatment of postmenopausal women with hormone receptor positive early invasive or advanced breast cancer. · Broadcast footage of Arimidex, is available at: www.thenewsmarket.com/astrazeneca .