06 Oct 2006
New data from the first study of its kind, show that, in postmenopausal women whose advanced breast cancer is both hormone receptor-positive (HR+) and HER2-positive, a combination of ArimidexTM (anastrozole) plus Herceptin® (trastuzumab) keeps cancer under control for significantly longer than hormonal therapy alone (anastrozole).1 The median progression-free survival was 4.8 months versus 2.4 months, respectively. These data were presented at the 31st European Society for Medical Oncology (ESMO) Congress today.
Around 75 percent of postmenopausal women with breast cancer are known to have HR+ disease and are eligible for treatment with Arimidex. As many as a quarter of these women will also be HER2-positive, which means that they have a particularly aggressive form of cancer, with a higher likelihood of relapse. For these particular women with so-called ‘co-positive' cancers, ‘Co-positive' breast cancer patients have tumour cells that both respond to oestrogen and HER2 protein, which stimulate growth of the cancer. The opportunity to take a combination of two highly effective anti-cancer drugs will be a welcome addition to their treatment programme.
The data presented at ESMO today continue to highlight the current and future potential of Arimidex in breast cancer. Arimidex was the first treatment shown to improve upon the efficacy and tolerability of tamoxifen in early breast cancer, resulting in significant changes to treatment practice. Now Arimidex becomes the first treatment of its kind to demonstrate a benefit in combination with Herceptin in advanced disease.
Arimidex in early breast cancer
Additional data presented for the first time in Europe today, confirm the benefits of initiating Arimidex directly after surgery in early breast cancer patients. Postmenopausal, HR+ early breast cancer patients are 26% less likely to suffer a disease recurrence if treatment is started with Arimidex rather than tamoxifen. Data from the mature, 68-month analysis of the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial, show that the majority of the recurrences seen with tamoxifen occur within the first few years of treatment, emphasising the importance of starting Arimidex treatment early.2
“Preventing recurrence is the primary aim of adjuvant treatment - if the cancer doesn't come back, you can't die from it,” explained Professor Joan Houghton, Senior Lecturer in Clinical Trials, Department of Surgery, University College London, UK.
“In the ATAC trial, over half of the additional recurrences seen with tamoxifen occurred within the first two and a half years of surgery. There may still be a place for tamoxifen in early breast cancer, but these data show us that treating women with ‘Arimidex', from the outset, provides the optimal protection against early recurrence.”
Importantly, women on Arimidex also suffered far fewer side effects compared with tamoxifen, meaning that a significantly greater number were able to complete their treatment.3 One of the key considerations with using tamoxifen is that it is known to be associated with some rare, but life-threatening side effects, the majority of which were also seen to occur in the first few years of treatment.
-- Women who took Arimidex experienced fewer strokes, fewer DVTs and fewer gynaecological side effects than women who took tamoxifen, over a five-year treatment period.3
-- Women on Arimidex were four times less likely to undergo a hysterectomy - a procedure often undertaken as a result of gynaecological abnormalities. 3
Side effects that were significantly increased with Arimidex compared with tamoxifen were fractures and joint disorders.3 When balanced against the life-threatening side effects of tamoxifen, the risk of fractures with Arimidex is seen as predictable and manageable and the risk:benefit ratio for adjuvant therapy is consistently in favour of Arimidex compared with tamoxifen.
Professor Robert Mansel, Department of Surgery, Wales College of Medicine, Cardiff University and member of the ATAC Steering Committee stated: “Starting therapy with tamoxifen puts patients at risk of preventable recurrences and avoidable serious side effects. It took a long time for us to improve upon tamoxifen, but with the mature data we have now for Arimidex, we know we have a more effective and better tolerated treatment to help our patients stay free from breast cancer.”
About HR+ and HER2+ tumours:
--In HR+ breast cancer, the tumour cells carry receptors on their surface, which respond to oestrogen and stimulate the growth of the tumour. Approximately 75% of postmenopausal breast tumours are hormone receptor-positive.
--In HER2-positive breast cancer, the tumours have an increased quantity of the HER2 protein on the surface of the cells. Tumours of this type are particularly aggressive. HER 2-positivity affects around 20-30% of women with breast cancer.
-- Arimidex is the most comprehensively studied of all the AIs and the only one with efficacy and tolerability data for the full five-year (median follow-up 68 months) adjuvant setting.4
1. Kaufman, B. Trastuzumab plus anastrozole prolongs progression-free survival in postmenopausal women with HER2 positive, hormone-dependent metastatic breast cancer (MBC). Abstract no. LBA2, presented at the ESMO 2006, Istanbul, Turkey, 29th Sept - 3rd Oct 2006
2. Houghton, J on behalf of the ATAC Trialists' Group, Initial adjuvant therapy with anastrozole (A) reduces rates of early breast cancer recurrence and adverse events compared with tamoxifen (T). Abstract no 243, presented at the ESMO 2006, Istanbul, Turkey, 29th Sept - 3rd Oct 2006
3. Mansel, R on behalf of the ATAC Trialists' Group. Tolerability of anastrozole (A) compared with tamoxifen (T): mature data in the adjuvant setting Abstract no 244, presented at ESMO 2006, Istanbul, Turkey, 29th Sept - 3rd Oct 2006.
4. ATAC Trialists' Group. Results of the ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial after completion of 5 years' adjuvant treatment for breast cancer. Lancet, 2005; 365 (9453): 60-62.