Clinical outcomes of everolimus in patients with hormone receptor positive breast cancer: a real-world analysis

AIMS: The study aimed to evaluate the effectiveness and safety of everolimus combined with endocrine therapy in patients with hormone receptor-positive, human epidermal growth factor receptor-2 negative (HR+/HER2-) advanced breast cancer. METHODS: Data from adult patients with HR+/HER2- advanced breast cancer at Beijing Cancer Hospital between January 2012 and February 2025 were analyzed retrospectively. RESULTS: A total of 137 patients were included and the median progression-free survival (PFS) was 4.13 months (95% confidence interval [CI]: 2.86-5.40). The objective response rate and disease control rate (DCR) were 10.9% and 51.1%, respectively. No significant difference was found in PFS between different lines of therapy (p = 0.433) or different combination drugs with everolimus (p = 0.528). The median PFS in patients without prior use of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors was 4.20 months, compared to 3.07 months in patients previously treated with CDK4/6 inhibitors (p = 0.466). The patients with prior CDK4/6 inhibitors for more than six months exhibited an extended PFS when subsequently treated with everolimus plus endocrine therapy (7.63 vs. 2.03 months, p<0.001). Meanwhile, everolimus-based treatment was generally well-tolerated. CONCLUSION: For patients with HR+/HER2- advanced breast cancer, everolimus combined with endocrine therapy may serve as an alternative option after disease progression on CDK4/6 inhibitors.