Abstract P5-04-29: Efficacy and safety of low-dose everolimus in Chinese HR-positive, HER2-negative metastatic breast cancer patients

Abstract

Abstract Background: Everolimus has been testified to be effective among postmenopausal women with hormone receptor-positive human epidermal growth factor receptor-2 negative (HR+/HER2-) metastatic breast cancer (MBC). However, everolimus at dose of 10mg was accompanied by a higher incidence of mTOR-inhibitor class-effect adverse events (AEs) which usually leading to dose reduction or interruption. Additionally, some studies suggested that there was no correlation between dose intensity (5 vs. 10 mg labeled dose) and efficacy. Consequently, we conducted the present study aiming to explore the efficacy and safety of everolimus at dose of 5 mg plus endocrine therapy in Chinese population. Methods: 68 HR+/HER2- MBC patients were included in this exploratory study who received everolimus at the dose of 5mg in Zhejiang Cancer Hospital between September 2014 and September 2017. Progression free survival(PFS) and overall survival(OS) were estimated by the Kaplan- Meier method, and the hazard ratios(HRs) and corresponding 95% confidence intervals(CIs) were estimated using the Cox proportional harzard model. Besides, objective response rate(ORR), clinical benefitrate(CBR) and safety profile were also evaluated. Results: After a median follow up of 14 months, PFS was 5.3 months (95%CI 4.2-6.4), and OS was immature. 16(23.5%) were at the first or second-line, 52(76.5%) were at third-line or later. PFS for the first and second-line is significantly longer than that for the third-line or later (12.9 months vs. 4.6 months, P=0.009, HR=0.395, 95% CI=0.192-0.811). 11(16.2%) achieved partial response (PR), 42(61.7%) had stable disease (SD), and 15(22.1%) reported progressive disease (PD). The ORR and CBR were 16.2%, 35.2%, respectively. Most common all grade adverse events were stomatitis(26.5%), fatigue(10.0%), infection(11.8%), thrombocytopenia(5.9%), anemia(4.4%), hyperglycemia(4.4%). The most common ≥3 grade adverse events were stomatitis(4.4 %), infection(2.2%) and thrombocytopenia(1.1%). Conclusions: The combination of low-dose everolimus and endocrine therapy was highly effective especially at the earlier line in Chinese population. And the safety profiles were similar to previous studies but the incidences were greatly lower. The combination of low-dose everolimus and endocrine therapy may become a proper option for HR+/HER2- MBC. Citation Format: Shao X, Wang X, Chen Z, Zheng Y. Efficacy and safety of low-dose everolimus in Chinese HR-positive, HER2-negative metastatic breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-04-29.