Analysis of the activity and safety of weekly low-dose bevacizumab-based regimens in heavily pretreated patients with metastatic breast cancer.

BACKGROUND: Currently, there are no standard regimens for metastatic breast cancer patients (MBC) who have failed ≥ 3 chemotherapy treatments. The aim of this study was to assess whether weekly low-dose bevacizumab-based regimens were well tolerated and would improve efficacy in MBC patients who had failed numerous therapies.

METHODS: Seventeen patients with MBC who were heavily pretreated with a median of five regimens of therapy (range 1-10) between 2012 and 2016 were included in the analysis. Bevacizumab was administered at a dose of 100 mg intravenously once a week combined with one or two types of chemotherapeutic drugs until confirmed disease progression or an intolerable adverse event was observed. Patient characteristics, objective response rate, clinical benefit rate, progression-free survival, and toxicity were assessed.

RESULTS: All 17 patients had been pretreated with taxane-based and anthracycline-based chemotherapy. Weekly low-dose bevacizumab combined with one or two types of chemotherapeutic drugs, which had usually not been previously used (e.g. etoposide, irinotecan, pemetrexed, methotrexate, and nab-paclitaxel), was administered. Three patients achieved a partial response, while one had stable disease for > 24 weeks, and the clinical benefit rate was 23.5%. Median progression-free survival was 3.4 months (95% confidence interval 2.0-4.8). The most common hematological adverse events were neutropenia, anemia, and thrombocytopenia. Bevacizumab-related adverse events included grade 1 bleeding (17.6%) and grade 2 hypertension (5.9%).

CONCLUSIONS: Weekly low-dose bevacizumab combined with chemotherapy shows a relatively favorable clinical response and tolerable toxicity, providing a feasible option for heavily pretreated MBC patients.