Efficacy and toxicity of everolimus plus exemestane in third and later lines treatment of hormone receptor-positive, HER2-negative metastatic breast cancer

Aim: In daily practice, everolimus plus exemestane therapy has begun to be used in the later-lines as it has been demonstrated that treatments such as cyclin-dependent kinase (CDK) 4/6 inhibitors and fulvestrant, alone or in combination, are more effective in hormone receptor (HR)-positive metastatic breast cancer (MBC). The aim of this study is to evaluate the efficacy and toxicity of everolimus plus exemestane in the third line and later-lines on HR-positive Human Epidermal Growth Factor Receptor 2 (HER2)-negative MBC treatment with real-life data. Methods: Patients who received everolimus plus exemestane with the diagnosis of HR-positive and HER2-negative MBC between November 2013 and March 2020 were included in this retrospective cohort study. Clinicopathological characteristics of patients and treatment related toxicities were evaluated retrospectively. Results: The median age of the 33 patients included in the study was 59 (30-77) years. Twenty-three (69.7%) of the patients had visceral metastasis, while 10 (30.3%) had only bone metastasis. Everolimus plus exemestane was used in the third line in 22 (66.6%) patients and later-lines in 11 (33.3%) patients. The median follow-up time was 15.5 months (0.3-35.5). Median progression-free survival (PFS) and overall survival (OS) were 7.0 (5.1-9.0, 95% CI) months and 21.3 (13.4-29.2, 95% CI) months, respectively. Median PFS of patients with only bone metastasis and visceral metastasis were similar (7.2 vs 6.4 months, P=0.96). Conclusion: Everolimus plus exemestane is an effective and tolerable treatment choice in the later-lines in the treatment of HR-positive HER2-negative MBC.