AstraZeneca announced that Faslodex 500mg (fulvestrant) has gained marketing approval from the European Commission for the treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer whose disease has recurred (come back) or progressed (spread) while on an anti-estrogen treatment (e.g. tamoxifen).

The approval was given following the recent positive opinion from the European Medicines Agency's (EMA's) Committee for Medicinal Products for Human Use (CHMP) on data from a comprehensive clinical development programme that included the phase III CONFIRM (COmparisoN of Faslodex In Recurrent or Metastatic breast cancer) study.

The CONFIRM study, presented for the first time at the recent annual San Antonio Breast Cancer Symposium (SABCS) in the USA, demonstrated fulvestrant 500mg significantly improved disease control in patients with metastatic breast cancer, without affecting tolerability, when compared with the 250mg dose.1 The data revealed a statistically significant 20% reduction in the risk of disease progression (assessed as time to disease progression (TTP)) for patients receiving the 500mg dose of fulvestrant (n=362), compared with 250mg (n=374);(HR 0.80; 95% CI 0.68-0.94, p=0.006). As a result, 34% of patients in the fulvestrant 500mg group remained alive and progression-free* after 1 year compared with only 25% of those in the 250mg group.

The main goal of metastatic breast cancer treatment is to prevent disease progression whilst maintaining quality of life. Fulvestrant has a different mechanism of action from other endocrine therapies; in addition to blocking the action of estrogen at its receptor, it also disrupts estrogen signalling, leading to down-regulation of the estrogen 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.

The new 500mg dose will be administered as two 250mg injections.

Dr Di Leo added, “Fulvestrant 500mg represents a significant improvement in the management of metastatic breast cancer. The clinical development programme, which was completed with the recent findings of the CONFIRM study, indicated that the 500mg dose enhances estrogen receptor down-regulation, providing a new, effective option to regain and maintain control over this devastating disease.”

Prior to the European Commission’s approval, fulvestrant 250mg was approved for the treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer who had relapsed on or after adjuvant anti-estrogen therapy or whose disease had progressed on therapy with an anti-estrogen. Fulvestrant 250mg had been demonstrated to be at least as effective as other standard endocrine therapies but with the potential advantage of prolonging disease control due its different mechanism of action. Evidence from the now complete clinical development programme including CONFIRM, FIRST (Faslodex fIRst line Study comparing endocrine Treatments) and NEWEST (Neoadjuvant Endocrine therapy for Women with Estrogen-Sensitive Tumours) reinforces that increasing the dose of fulvestrant 250mg to 500mg significantly prolongs disease control without compromising tolerability.

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.

Fulvestrant is an estrogen receptor antagonist with no known agonist effects used to treat postmenopausal women with hormone-receptor positive metastatic breast cancer. It has a distinct and different mode of action to other endocrine therapies and is the only treatment in this class of drugs. Findings from the clinical development programme (CONFIRM, NEWEST and FIRST) have suggested that fulvestrant 500mg enhances estrogen receptor down-regulation and efficacy compared with the currently approved 250mg dose.

AstraZeneca is a global, innovation-driven biopharmaceutical business with a primary focus on the discovery, development and commercialisation of prescription medicines.