Efficacy and safety of low-dose everolimus combined with endocrine drugs for patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer

BACKGROUND: To analyze the efficacy and safety of everolimus 5 mg/day in combination with endocrine drugs in the treatment of hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer using real-world clinical data. METHODS: Clinical data of hormone receptor (HR)-positive and HER2-negative patients with advanced breast cancer treated with everolimus combined with endocrine drugs in our center between August 2012 and May 2017 were retrospectively analyzed. Curative effect and adverse reactions were evaluated. RESULTS: A total of 110 patients were enrolled in this study, and 87.3% received salvage chemotherapy. The median number of salvage treatment lines was 5 (range: 1–19). The median follow-up duration was 12 months (range: 1–56.3 months), the overall response rate (ORR) was 6.4%, the clinical benefit rate (CBR) was 31.8%, the median progression-free survival (mPFS) was 4.0 months (95% CI: 2.9–5.1 months), and the median overall survival (OS) was 17 months (95% CI: 12.1–21.9 months). The mPFS for patients who received ≤2 treatment line was 11.8 months (95% CI: 4.3–19.3 months). Univariate and multivariate analyses suggested that absence of liver metastases, secondary endocrine resistance, and number of metastasis sites <3 were the main factors influencing the benefit of everolimus combined with endocrine therapy. The most common adverse events of grade 3 were: stomatitis (5.5%), non-infectious pneumonia (1.8%), and erythra (1.8%). No grade 4 adverse reactions were observed. CONCLUSIONS: Our results showed that everolimus (5 mg/day) combined with endocrine therapy was effective and relatively safe for patients with hormone receptor-positive, HER2-negative metastatic breast cancer.