Bevacizumab in metastatic breast cancer: a meta-analysis of randomized controlled trials

Numerous studies have demonstrated that angiogenesis and in particular VEGF over-expression play an essential role in the progression and metastatic potential of breast cancer. Bevacizumab is a humanized recombinant monoclonal antibody that specifically blocks the binding of VEGF to high-affinity receptors and it has been recently used for the treatment of metastatic breast cancer. We conducted a meta-analysis to synthesize available evidence for use of bevacizumab in metastatic breast cancer patients. Systematic review and meta-analysis of available trials. Primary outcomes were overall survival, progression free survival (PFS) and objective response rate (ORR). Five trials were identified with 3,163 eligible patients. Combination of bevacizumab and chemotherapy resulted in a statistically significant improvement in PFS (HR = 0.70, 95% CI 0.60-0.82, P = 9.3 x 10(-6)) and ORR (RR = 1.26, 95% CI 1.17-1.37, P = 9.96 x 10(-9)) compared with chemotherapy alone. Differences in objective response rates were substantial independently by the type of chemotherapy used, while PFS advantages were observed only for taxanes. The pooled HR for overall survival did not show significant advantage for the use of bevacizumab compared to placebo arm (HR = 0.90, 95% CI 0.80-1.03, P = 0.119). This meta-analysis shows that the addition of bevacizumab to chemotherapy offers meaningful improvement in PFS and ORR in patients with metastatic breast cancer. Bevacizumab treatment might be suggested for treatment of 1st line metastatic breast cancer, but more data are needed until statistical overall survival differences will be documented and firm guideline recommendation could be given.