Comparative Efficacy of CDK4/6 Inhibitors Plus Aromatase Inhibitors Versus Fulvestrant for the First-Line Treatment of Hormone Receptor-Positive Advanced Breast Cancer: A Network Meta-Analysis

Several endocrine therapies are available for postmenopausal women with hormone receptor-positive (HR +) advanced breast cancer (ABC). Given the absence of direct comparisons between fulvestrant and cyclin-dependent kinase 4/6 inhibitors (CDK4/6is) in combination with aromatase inhibitors (AIs), which are both used as standard first-line treatments for ABC, an indirect comparison using a network meta-analysis may be advantageous for decision making. We performed a network meta-analysis to compare the efficacies of fulvestrant and CDK4/6is plus AIs as the first-line treatment of postmenopausal breast cancer patients. In order to compare these treatments, we searched the PubMed, Cochrane Library, and EMBASE databases for randomized controlled trials of first-line endocrine treatment for advanced or metastatic breast cancer until October 2018. We included a total of 11 eligible trials with 5448 patients. The hazard ratios (HRs) for the efficacies of the different treatments were used as inputs in the network meta-analysis. In the overall analysis, CDK4/6is plus AIs, including palbociclib plus letrozole, ribociclib plus letrozole, and abemaciclib plus nonsteroidal AI (letrozole or anastrozole), are all superior to 500 mg fulvestrant (HR = 0.50, 95% confidence interval [CI] 0.37–0.68; HR = 0.50, 95% CI 0.35–0.71; and HR = 0.49, 95% CI 0.34–0.71; respectively). Within the limitations of this network meta-analysis, the comparison indicates that CDK4/6is plus AIs might represent a better option for HR+ ABC as a first-line endocrine treatment compared with fulvestrant.