The data presented today from FIRST, a Phase II open-label study, showed that fulvestrant 500mg significantly delayed disease progression compared with anastrozole, said Professor John Robertson, University of Nottingham City Hospital, UK.
“This provides further evidence of the efficacy of fulvestrant 500mg in women with hormone receptor positive advanced breast cancer.”
New data presented today at the CTRC-AACR 33rd Annual San Antonio Breast Cancer Symposium, USA, suggest fulvestrant 500mg offers improved disease control compared with the aromatase inhibitor, anastrozole, when used as a first-line treatment for hormone receptor positive breast cancer.
The follow-up data from the FIRST (FASLODEX fIRst line Study comparing endocrine Treatments) trial – a randomised, open-label, phase II trial in post-menopausal women with locally advanced or metastatic disease – showed a 34% reduction in risk of progression with fulvestrant 500mg compared with anastrozole.
The main goal of advanced breast cancer treatment is to prevent disease progression whilst maintaining quality of life. This new analysis was undertaken when 80% of patients had discontinued study treatment, as only 36% had progressed in the primary analysis in 2008.
The data revealed that women who received fulvestrant 500mg had significantly prolonged time to disease progression (TTP) (hazard ratio=0.66; 95% confidence interval 0.47, 0.92; p-value=0.01), corresponding to a median TTP of 10.3 months longer than for anastrozole 1mg (23.4 versus 13.1 months respectively).
These data are consistent with the findings of the primary analysis, which showed that women receiving fulvestrant 500mg experienced a clinical benefit rate of 73% compared with 67% for those receiving anastrozole 1mg (p=0.386).
No new safety concerns were identified for fulvestrant 500mg, which was well tolerated, and patients who progress on either fulvestrant 500mg or anastrozole 1mg remain sensitive to subsequent endocrine treatments (41% versus 42% respectively).
Fulvestrant has a different mechanism of action from other endocrine therapies; in addition to blocking the action of oestrogen at its receptor, it also disrupts oestrogen signalling, leading to down-regulation of the oestrogen receptors in the tumour as well as disruption of other cancer growth pathways.
This distinct mechanism of action not only reduces the growth and spread of the cancer but may help to reduce or delay resistance to treatment.
These data add to an expanding body of clinical evidence including the CONFIRM (COmparisoN of FASLODEX In Recurrent or Metastatic breast cancer) and NEWEST (Neoadjuvant Endocrine therapy for Women with Estrogen-Sensitive Tumours) studies which reinforce the use of fulvestrant at its newly approved dose of 500mg.
Most recently, CONFIRM showed that increasing the dose of fulvestrant 250mg to 500mg significantly prolongs disease control without compromising tolerability.
Based on this evidence, fulvestrant 500mg was licensed in Europe for the treatment of hormone receptor-positive metastatic breast cancer in post-menopausal women with disease progression following anti-oestrogen therapy in March 2010 and by the FDA in the US in September 2010.
For over 30 years, AstraZeneca has played a pivotal role in breast cancer research and treatment.
Throughout this time, scientists at AstraZeneca have researched and developed a range of endocrine therapies that have made significant contributions to the treatment of both early and metastatic breast cancer around the world.