Important new data from two studies presented at the 27th Annual San Antonio Breast Cancer Symposium (SABCS) in the USA, suggest that 'Faslodex' (fulvestrant) is an effective and well tolerated treatment for postmenopausal women with advanced breast cancer who have experienced disease progression on aromatase inhibitor therapy.

The first of the two studies was conducted by Dr Lucien Perey, from the Swiss Group for Clinical Cancer Research (SAKK), in Bern, Switzerland. In this phase II trial, 67 postmenopausal women with advanced breast cancer whose disease had progressed after previous treatment with both tamoxifen and then an aromatase inhibitor were assessed. The results showed 28 per cent of patients achieved a clinical benefit (PR+SD>/= 24 weeks).

This finding is further supported by data from the second study, conducted by Dr James Ingle, from the Mayo Clinic in Minnesota, USA. In this phase II trial, 77 postmenopausal women with advanced breast cancer whose disease progressed following treatment with an aromatase inhibitor and, at most, one additional hormonal agent, were assessed. These data showed that a similar clinical benefit rate (PR+SD>/= 24 weeks*) was observed in almost one third (29 per cent) of the patients in the trial. These data also showed that 'Faslodex' was well tolerated, with only mild-to-moderate side effects being reported and no patients withdrawing due to adverse events.

"The data from these two studies represent an important finding since they suggest that patients with advanced breast cancer who have progressed on aromatase inhibitor therapy have an additional effective and well tolerated hormonal treatment option at their disposal, which further delays the need to use chemotherapy" commented Dr Perey. "Significantly, what is also key here is the fact that both studies have shown a similar level of efficacy and tolerability for patients who have received prior aromatase inhibitor therapy and who were then treated with 'Faslodex'."

Previous data, which form the basis of its current approved indication, have confirmed that 'Faslodex' is effective and well tolerated in postmenopausal women with advanced breast cancer whose disease has progressed following treatment with tamoxifen. However, as aromatase inhibitors such as 'Arimidex' (anastrozole) have now demonstrated their superiority over tamoxifen in both the adjuvant setting and as first line therapy for advanced breast cancer, the changing treatment paradigm means that the efficacy and tolerability of 'Faslodex' following aromatase inhibitor therapy has become an important question for clinicians and patients alike. These new data therefore represent an important development that will be eagerly welcomed by the oncology community, since they suggest that women who have received prior non-steroidal aromatase inhibitor therapy now have an additional effective and well-tolerated hormonal therapy with which to fight their disease, extending the benefits of hormonal therapy and delaying the need for the more aggressive chemotherapy.

In order to confirm findings from studies such as these, AstraZeneca are undertaking two large-scale international, randomised controlled trials of 'Faslodex' following aromatase inhibitor therapy, known as the EFECT trial (Evaluation of Fulvestrant versus Exemestane Clinical Trial) and the SOFEA trial (Study of 'Faslodex', Exemestane and 'Arimidex'), both of which are expected to confirm the efficacy and tolerability of 'Faslodex' in this important setting.

The possibility of extending the benefits of 'Faslodex' treatment to all women with advanced disease at the first opportunity is also being explored in more detail. Additional data presented at the SABCS congress have shown efficacy for 'Faslodex' as a first-line therapy for postmenopausal patients with advanced breast cancer. These data come from a study conducted by Professor John Robertson at Nottingham City Hospital in the UK, which assessed 30 patients with previously untreated advanced breast cancer who received 'Faslodex' as their initial treatment. The results show continued and maintained down regulation of oestrogen receptor levels for a sustained period (six months). Patients treated with 'Faslodex' who had evaluable disease at six months had a clinical benefit rate of 79 per cent (PR+SD>/= 24 weeks). Importantly, the data from the study also showed that the oestrogen receptor was present at the time of disease progression in all patients, supporting the use of further hormonal therapies following 'Faslodex' treatment. This is significant since it means that the benefits of well-tolerated hormonal therapy may be extended, delaying the need to resort to chemotherapy with its well recognised side effects.

"These data from this phase II trial highlight the potential of Faslodex as an effective first line treatment for postmenopausal women with locally advanced and advanced breast cancer" commented Professor Robertson. "These data add to the increasingly extensive data base which suggest that 'Faslodex' is both a very effective and arguably the best tolerated hormonal therapy available."