From 3 July 2014, Halaven® (eribulin) is licenced in the UK for the treatment of patients with locally advanced or metastatic breast cancer (MBC) who have progressed after at least one chemotherapeutic regimen for advanced disease. Prior therapy should have included an anthracycline and a taxane in either the adjuvant or metastatic setting, unless patients were not suitable for these treatments.
"Today's announcement means women in the UK with advanced breast cancer will now have earlier access to the only single agent chemotherapy proven to significantly improve overall survival after metastatic anthracycline and taxane treatment. Being able to use eribulin after only one prior chemotherapy regimen is an important option for these women," commented Professor Stephen Johnston, Professor of Breast Cancer Medicine and Consultant Medical Oncologist at The Royal Marsden and The Institute of Cancer Research, London.
This new indication for eribulin follows Marketing Authorisation Approval (MAA) for earlier use in advanced disease from the European Commission on 3 July 2014. MAA was based on clinical evidence from two global Phase III trials; EMBRACE (Eisai Metastatic Breast Cancer Study Assessing Treatment of Physician's Choice Versus Eribulin) and study 301. These studies involved more than 1,800 women.
Study 301, a head-to-head trial of eribulin vs capecitabine of 1,102 women, had a co-primary endpoint of overall survival and progression-free survival. The study demonstrated a trend favouring improved overall survival with eribulin compared to capecitabine in the intention-to-treat population, although the improvement was not statistically significant.3 Women treated with eribulin had a median overall survival of 15.9 months versus 14.5 months with capecitabine (HR 0.879; 95% CI: 0.770-1.003; p=0.056).3 For women with human epidermal growth factor receptor 2 (HER2) negative metastatic breast cancer, overall survival was 15.9 months for eribulin vs 13.5 months for capecitabine (HR 0.838; 95% CI: 0.715-0.983).3 The most common adverse events reported for eribulin and capecitabine (≥20% all grades) were neutropenia (54% vs 16%), hand-foot syndrome (<1% vs 45%) alopecia (35% vs 4%), leukopenia (31% vs 10%), diarrhoea (14 vs 29%) and nausea (22% vs 24%), respectively.
EMBRACE showed eribulin can prolong median overall survival in heavily pre-treated women with MBC compared to women receiving an alternative treatment of physician's choice by 2.7 months (13.2 vs 10.5 HR 0.81 (95% CI 0.67, 0.96) nominal p=0.014). The most commonly reported adverse reactions in the eribulin study arm were fatigue (asthenia), a decrease in infection-fighting white blood cells (neutropenia), hair loss (alopecia), numbness and tingling in arms and legs (peripheral neuropathy), nausea and constipation.2 EMBRACE is one of only 25 studies to demonstrate a significant extension in overall survival (as primary or secondary endpoint) in MBC in the last 40 years.
Eribulin is a non-taxane, microtubule dynamics inhibitor currently indicated for the treatment of people with breast cancer who have previously received at least two chemotherapeutic regimens for metastatic disease and whose prior therapy should have included an anthracycline and a taxane. Eribulin belongs to a class of antineoplastic agents, the halichondrins, which are natural products, isolated from the marine sponge Halichondria okadai. It is believed to work by inhibiting the growth phase of microtubule dynamics which prevents cell division.
Global Phase III Clinical Study 305 (EMBRACE)2
EMBRACE (Eisai Metastatic Breast Cancer Study Assessing Treatment of Physician's Choice (TPC) Versus Eribulin E7389) was an open-label, randomised, global, multi-centre, parallel two-arm study designed to compare overall survival in women treated with eribulin versus a TPC arm. TPC was defined as any single-agent chemotherapy, hormonal treatment or biologic therapy approved for the treatment of cancer; or palliative treatment or radiotherapy administered according to local practice. The study included 762 participants with metastatic breast cancer who previously had been treated with at least two and a maximum of five prior chemotherapies, including an anthracycline and a taxane. The vast majority (96%) of participants in the TPC arm received chemotherapy.
In the total phase III EMBRACE study population, eribulin was shown to prolong median overall survival in heavily pre-treated women with metastatic breast cancer compared to women receiving TPC by 2.7 months (13.2 vs 10.5 HR 0.81 (95% CI 0.67, 0.96) nominal p=0.014). A pre-planned analysis of participants from Region 1 of the study (North America/Western Europe/Australia) showed a significant median overall survival benefit of eribulin over TPC of 3.0 months (nominal p=0.031).
The most commonly reported adverse reactions among people treated with eribulin in the EMBRACE study were fatigue (asthenia), a decrease in infection-fighting white blood cells (neutropenia), hair loss (alopecia), numbness and tingling in arms and legs (peripheral neuropathy), nausea and constipation. Peripheral neuropathy was the most common adverse event leading to discontinuation from eribulin, occurring in less than 5% of the women involved in the EMBRACE trial. Neutropenia only led to eribulin discontinuation for 0.6%. Death due to serious side effects, discontinuation and dose interruptions to treatment were lower in the eribulin arm of the trial compared with the TPC arm.
Global Phase III Study 3013
Study 301 was an open-labelled, randomised, two-parallel-arm, multicentre study of eribulin versus capecitabine in 1,102 women with locally advanced or metastatic breast cancer previously treated with anthracyclines and taxanes, either in the (neo) adjuvant setting or for locally advanced or metastatic disease. Women in the study received zero to two previous chemotherapies for advanced disease.
The study opened in 2006 and the last patient was randomised in 2010. Patients were randomised to treatment with either eribulin 1.23mg/m2 (administered intravenously over two to five minutes on days 1 and 8, every 21 days) or capecitabine 2.5g/m2 (administered orally twice daily in two equal doses on days 1 to 14, every 21 days).
Study 301 had a co-primary endpoint of OS and PFS. The study demonstrated a trend favouring improved OS with eribulin compared to capecitabine in the ITT population, although the improvement was not statistically significant. Women treated with eribulin had a median OS of 15.9 months (HR 0.879; 95% CI: 0.770-1.003; p=0.056) versus 14.5 months with capecitabine. The trial did not meet the pre-specified endpoint for progression-free survival, with 4.1 and 4.2 months for eribulin and capecitabine respectively (HR 1.079; 95% CI: 0.932-1.250; p=0.305).
1-,2- and 3- year overall survival rates for eribulin versus capecitabine showed an early improvement which was maintained throughout the study (1 year, 64.4% eribulin vs 58.0% capecitabine (P=0.0351), 2 year 32.8% eribulin vs 29.8% capecitabine (P=0.324), 3 year, 17.8% eribulin vs 14.5% capecitabine (P=0.175).
Unlike studies conducted today, study 301 included all women regardless of their human epidermal growth factor receptor 2 (HER2), oestrogen receptor (ER) or progesterone receptor (PR) status. Patients are usually tested for their HER2 status as there are now effective treatments specifically for patients with the HER2 mutation. HER2 positive patients would generally be treated with anti-HER2 positive targeted therapy. For women with HER2 negative metastatic breast cancer (n=755), OS was 15.9 months for eribulin vs 13.5 months for capecitabine (HR 0.838; 95% CI: 0.715-0.983). In the HER2 positive population, OS was 14.3 months for eribulin vs 17.1 months for capecitabine (HR; 95% 0.965; CI: 0.688-1.355).
Adverse events in Study 301 were consistent with the known profile of both drugs.
Metastatic Breast Cancer
Breast cancer is the most common cancer in the UK, accounting for 30% of all new cases of cancer in females. There are an estimated 570,000 people living in the UK today who have been diagnosed with breast cancer. In the UK around 50,000 new cases of breast cancer are diagnosed every year, rising to 300,000 women in Europe, of whom about one third subsequently develop metastatic disease., Metastatic disease is an advanced stage of the disease that occurs when cancer spreads beyond the breast to other parts of the body.