The role of CDK4/6 inhibitors in older and younger patients with breast cancer: A systematic review and meta-analysis

Introduction: Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors have an extremely important impact on the treatment of hormone-sensitive breast cancer (BC) and have radically changed the first-line treatment for metastatic disease with increased rates of treatment response, overall survival (OS), and progression-free survival (PFS). We performed a pooled analysis of randomized trials to validate or refute the hypothesis that there is a significant survival benefit of adding anti-CDK4/6 inhibitors to standard endocrine therapy (ET) in older patients with advanced BC.Methods: We selected only English-language phase II/III randomized controlled trials that compared ET alone with ET with anti-CDK4/6 inhibitors in the treatment of advanced BC, with subgroups reporting the outcomes of elderly patients (usually at least 65 years). The primary endpoint was OS.Results: The review process led to the inclusion of 12 articles and two meeting abstracts, including a total of 10 trials. The addition of CDK4/6 inhibitors to ET (letrozole or fulvestrant) significantly reduced mortality risk by 20% in younger patients (fixed-effect model; HR 0.80; 95% CI 0.72-0.9; p < 0.01) and 21% in older BC patients (HR 0.79; 95% CI 0.69-0.91; p < 0.01). No OS data were available for patients >= 70 years.Conclusion: This large, pooled analysis is the first to demonstrate that CDK4/6 inhibitors confer OS and PFS benefits in elderly patients (those aged >= 65 years) with advanced ER + BC and to indicate that it should be discussed with and offered to all patients after geriatric assessment and according to the toxicity profile.

Automated summary

This pooled analysis demonstrates that adding CDK4/6 inhibitors to standard endocrine therapy significantly reduces mortality risk and improves overall survival and progression-free survival in elderly patients with advanced ER+ breast cancer.