CDK4/6 Inhibitors in Combination With Hormone Therapy for HR+/HER2− Advanced Breast Cancer: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background This meta-analysis of randomized controlled trials aimed to comprehensively assess the efficacy and toxicity of cyclin-dependent kinase (CDK) 4/6 inhibitors in advanced breast cancer (ABC) with hormone-receptor positive (HR+) and human epidermal growth factor receptor 2 negative (HER2−) disease. Methods We performed a systematical search using Cochrane Library, PubMed, Embase, and Web of Science up to March 2018. Only phase 2 and 3 randomized clinical trials assessing the efficacy and toxicity of the combination regimen of CDK4/6 inhibitors plus hormone therapy compared with hormone therapy alone were eligible for this meta-analysis. The pooled analyses of relative risk (RR) and hazard ratio were carried out by Stata software. Results A total of 7 randomized controlled trials including 3854 patients with HR+/HER2− ABC were included in this meta-analysis. The pooled hazard ratio for progression-free survival was 0.54 (95% confidence interval, 0.49-0.59; P Conclusion CDK4/6 inhibitors plus hormone therapy can significantly prolong the progression-free survival of patients with HR+/HER2− ABC and improve the objective response rate compared to conventional hormone therapy alone. The combined regimen results in a higher risk of AEs, especially grade 3/4 AEs.