A network meta-analysis of everolimus plus exemestane versus chemotherapy in the first- and second-line treatment of estrogen receptor-positive metastatic breast cancer

The goal of this study was to compare the efficacy and toxicity of chemotherapy to exemestane plus everolimus (EXE/EVE) through a network meta-analysis (NMA) of randomized controlled trials. NMA methods extend standard pairwise meta-analysis to allow simultaneous comparison of multiple treatments while maintaining randomization of individual studies. The method enables "direct" evidence (i.e., evidence from studies directly comparing two interventions) and "indirect" evidence (i.e., evidence from studies that do not compare the two interventions directly) to be pooled under the assumption of evidence consistency. We used NMA to evaluate progression-free survival (PFS) and time to progression (TTP) curves in 34 studies, and response rate (RR) and the hazard ratios (HRs) of the PFS/TTP in 36 studies. A number needed to treat (NNT) analysis was also performed as well as descriptive comparison of reported toxicities. The NMA for PFS/TTP curves and for HR shows EXE/EVE is more efficacious than capecitabine plus sunitinib, CMF, megestrol acetate and tamoxifen, with an average of related-PFS/TTP difference ranging from about 10 months for capecitabine plus sunitinib to more than 6 months for tamoxifen. The NMA for overall RR shows that EXE/EVE provides a better RR than bevacizumab plus capecitabine, capecitabine, capecitabine plus sorafenib, capecitabine plus sunitinib, CMF, gemcitabine plus epirubicin plus paclitaxel, EVE plus tamoxifen, EXE, FEC, megestrol acetate, mitoxantrone, and tamoxifen. Finally, the NMA for NNT shows that EXE/EVE is more beneficial as compared to BMF, capecitabine, capecitabine plus sunitinib, CMF, FEC, megestrol acetate, mitoxantrone, and tamoxifen. The combination of EXE/EVE as first- or second-line therapy for ER+ve/HER2-ve metastatic breast cancer is more efficacious than several chemotherapy regimens that were reported in the literature. Toxicities also favored EXE/EVE in most instances.