Ann Palliat Med. 2022 Dec;11(12): 3727-3742
BACKGROUND: In previous studies on the application of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors combined with endocrine therapy in advanced breast cancer, the outcomes of overall survival (OS) were inconsistent. This systematic review and meta-analysis aimed to further evaluate the clinical efficacy and safety of CDK4/6 inhibitors combined with endocrine therapy on patients with hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer.METHODS: Randomized controlled trials (RCTs) comparing CDK4/6 inhibitors plus endocrine therapy and endocrine therapy alone in patients with HR-positive and HER2-negative advanced breast cancer were searched in the databases of PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), WANFANG and China Science and Technology Journal Database (VIP) up to November 2022. Hazard ratios (HRs) and confidence intervals (CI) of OS, progression-free survival (PFS), the time from randomization to the first recorded disease progression while the patient was receiving next-line therapy or death from any cause (PFS2), time to first subsequent chemotherapy after discontinuation (TTC), and objective response rate (ORR), clinical benefit rate (CBR), safety indicators were extracted. Stata 14.0 software was used for meta analysis and the Cochrane risk-of-bias tool 2.0 was used to evaluate the bias risk.
RESULTS: A total of 9 RCTs with 4,920 participants were included. The addition of CDK4/6 inhibitors to endocrine therapy significantly prolonged OS (HR 0.76; 95% CI: 0.69-0.84; P<0.001), regardless of the application in first-line and second-line treatment, compared with endocrine therapy alone. Similar benefit was observed in PFS (HR 0.56; 95% CI: 0.52-0.60; P<0.001). Moreover, the CDK4/6 inhibitors group improved results of ORR [relative risk (RR) 1.43; 95% CI: 1.27-1.62; P<0.001], CBR (RR 1.24; 95% CI: 1.08-1.41; P<0.01 and RR 1.11; 95% CI: 1.06-1.18; P<0.001), PFS2 (HR 0.68; 95% CI: 0.60-0.76; P<0.001) and TTC (HR 0.65; 95% CI: 0.58-0.72; P<0.001). One of the included RCTs had performance bias. Publication bias was not significant.
CONCLUSIONS: CDK4/6 inhibitors combined with endocrine therapy effectively prolong OS, PFS, PFS2, and TTC, and also improve ORR and CBR in patients with HR-positive, HER2-negative advanced breast cancer, and the safety was within the controllable range.
Keywords: Advanced breast cancer; CDK4/6 inhibitors; endocrine therapy; meta-analysis