Treatment sequence for hormone receptor-positive HER2-negative advanced breast cancer: Results of a retrospective analysis of Russian patients diagnosed with aBC in 2014-2021.

Abstract

e13032 Background: CDK4/6 inhibitors (CDK4/6i) in combination with endocrine therapy (ET) have dramatically changed therapeutic landscape of hormone receptor-positive HER2-negative advanced breast cancer (HR+ HER2- aBC). There are three iCDK4/6 in Russia, which are available and included into the clinical guidelines as a preferred first line treatment option beginning since 2018. The aim of this study was to assess evolution of treatment approaches to HR+ HER2- aBC and identify demographic and disease characteristics in correlation with available groups of therapy (chemotherapy, endocrine therapy ±mTOR inhibitors/ CDK4/6i). Methods: Аdult patients diagnosed with de novo or recurrent HR+ HER2- aBC in 2014-2021 identified in outpatient departments of Moscow state oncology hospitals were included into our non-interventional, descriptive, retrospective cohort study. Primary objective of this real-world study was to describe the rate of CDK4/6i usage in the first line setting. As a secondary objective, we describe patient and disease characteristics in iCDK4/6 group, as well as in the endocrine monotherapy and chemotherapy groups. Results: From the cohort of 1000 patients (full-set analysis population) 874 cases were selected, who received treatment since 2018. 45.9% (95% CI 42.6, 49.2) patients were treated with CDK4/6i in combination with endocrine therapy in the first-line setting. From them in the subgroups of patients with or without visceral metastases 50.5% (95% CI 45.5, 55.5) and 42.1% (95% CI 37.7, 46.5) were treated with CDK4/6i in the first line setting, respectively. Among 874 cases 78.0% (95% CI 75.3, 80.7) patients received endocrine therapy ± targeted therapy; in the subgroups of patients with or without visceral metastases 69.5% (95% CI 64.9, 74.1) and 84.9% (95% CI 81.7, 88.1) were treated with endocrine therapy ± targeted therapy in the first line setting, respectively. Conclusions: Endocrine therapy is a predominant therapeutic option in the first line setting for HR+ HER2- aBC. Clinical trial information: NCT04852081. [Table: see text]