LAUSR

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 < .001), and the pooled RR for the objective response rate in all intent‐to‐treat patients was 1.51 (95% confidence interval, 1.26‐1.81; P < .001). The pooled RRs for all grade adverse events (AEs) and grade 3/4 AEs were 1.07 (95% confidence interval, 1.03‐1.11; P < .001) and 2.81 (95% confidence interval, 2.54‐3.11; P < .001), respectively. However, to investigate the influence of CDK4/6 inhibitors on overall survival, sufficient follow‐up is still needed. 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. Micro‐Abstract We conducted a meta‐analysis that aimed to assess the efficacy and toxicity of cyclin‐dependent kinase (CDK) 4/6 inhibitors in hormone receptor–positive (HR+)/human epidermal growth factor receptor 2–negative (HER2−) advanced breast cancer (ABC) that assessed 7 randomized clinical trials involving 3854 patients. CDK4/6 inhibitors can significantly prolong the progression‐free survival of patients with HR+/HER2− ABC. The combined regimen of CDK4/6 inhibitors and hormone therapy results in a higher risk of adverse events.