Several interesting research developments for metastatic breast cancer (MBC) were presented at this year’s European Multidisciplinary Cancer Congress, formerly known as the joint Congress of the European Cancer Organization and the European Society for Medical Oncology (ECCO-ESMO), in Stockholm.
MBC poses a particular clinical challenge, with endocrine therapy remaining the primary option for the majority of patients. These patients live with the reality that they can no longer be cured, and so survival time and quality of life are key issues.
In the Breast Cancer Trials of Oral Everolimus trial (BOLERO-2), everolimus and exemestane versus endocrine therapy alone resulted in a significantly reduced relative risk of disease progression for patients with oestrogen receptor-positive, HER2-negative disease (57%). A significantly better progression-free survival (PFS) (median 6.9 months versus 2.8 months; HR 0.43, 95% CI 0.35 to 0.54, p<0.0001) and improved disease-free survival (median 10.6 months versus 4.1 months; HR 0.36, 95% CI 0.27 to 0.47, p<0.0001) was seen. Data on overall survival are eagerly awaited. According to Professor Jose Baselga, this treatment “could represent a new therapeutic option” for this group of women who have previously been treated with endocrine therapy.
The video below is the ESMO interview with Fabrice André, MD, PhD: who comments on the impact of the ph-III BOLERO-2 study and gives his perspective on clinical practice consequences for patients with hormone refractory advanced breast cancer.
Data has also been presented on the novel monoclonal antibody-guided therapy, trastuzumab emtansine (T-DM1), for HER2-positive MBC showing a 40% reduced risk of disease progression versus trastuzumab plus docetaxel (p=0.035). The idea of linking an antibody with chemotherapy is not new, but this is the first time it has been done successfully in the clinical setting.
Triple-negative MBC poses particular challenges to oncologists in terms of its heterogeneity. There is an absence of randomised data defining the most appropriate treatment for patients with triple-negative disease. It is known to be sensitive to chemotherapy, in particular anthracycline and taxane. However, it frequently recurs and more therapeutic options are required for these patients. In clinical practice, bevacizumab plus paclitaxel has been shown to result in similar outcomes for patients with triple-negative MBC as it does for non-triple-negative disease, and is also well tolerated. Clinical studies have shown that the median overall survival is 16 months for triple-negative patients versus 22.9 months for non-triple-negative cancer, the median PFS is 8 months versus 10.1 months and the overall response rate is 51% versus 65%, respectively.
Adding the poly ADP ribose polymerase (PARP) inhibitor, iniparib, to gemcitabine plus carboplatin may also benefit triple-negative MBC patients when used as second- or third-line therapy. The combination is associated with greater chances of overall and PFS versus chemotherapy alone but doesn’t appear to hold the same benefits as first-line therapy. A better understanding of its mechanism of action is needed to evaluate which patient populations may gain the most benefit from the combination.
In the last year, interesting data from the Eisai Metastatic Breast Cancer Study Assessing Treatment of Physician’s Choice Versus Eribulin E7389 trial (EMBRACE) has demonstrated significant improvements in overall survival for eribulin versus treatment of choice in women with MBC previously treated with at least an anthracycline and a taxane. It is believed to work by inhibiting cancer cell growth and is a first-in-class microtubule dynamics inhibitor belonging to the halichondrin class of antineoplastic agents.
There is an urgent need for therapies with a proven survival benefit for women with MBC who have already received multiple treatments.