Fulvestrant plus targeted agents versus fulvestrant alone for treatment of hormone-receptor positive advanced breast cancer progressed on previous endocrine therapy: a meta-analysis of randomized controlled trials

To compare the addition of targeted agents to fulvestrant with fulvestrant alone in hormone-receptor positive advanced breast cancer progressed on previous endocrine therapy; a meta-analysis of all relevant randomized controlled trials was performed. The PubMed, Embase databases and the Cochrane Central Register of Controlled Trials were searched for relevant publications reporting randomized controlled trials between January 2000 and June 2016. Progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), and toxicity were assessed. Eight trials with a total of 2,470 patients were included in this meta-analysis. Compared with fulvestrant alone, combination therapy improved PFS (HR = 0.79; 95% CI 0.72-0.87; P = 0.00), increased ORR (RR = 1.70; 95% CI 1.30-2.21; P = 0.00), and showed a trend of increase in DCR (RR = 1.27; 95% CI 0.96-1.69, P = 0.09). In network analysis, only CD4/6 and PI3K/m-TOR inhibitors showed significant treatment effects with a P-score of 0.9999 and 0.7615, respectively. Patients treated with combination therapy developed more grade 3 or greater toxic effects (RR = 1.24; 95% CI 1.13-1.36; P = 0.00). Combining targeted agents with fulvestrant showed benefit but with increased toxicity in patients with advanced breast cancer compared with fulvestrant alone. Biomarkers for treatment optimization are lacking. The CD4/6 and PI3K/m-TOR pathways merit further investigation.