RIBBON-2: a randomized, double-blind, placebo-controlled, phase III trial evaluating the efficacy and safety of bevacizumab in combination with chemotherapy for second-line treatment of human epidermal growth factor receptor 2-negative metastatic breast cancer

Abstract

Purpose: This phase III study compared the efficacy and safety of bevacizumab combined with standard chemotherapy regimens versus chemotherapy alone as second-line treatment of patients with human epidermal growth factor receptor 2 (HER2) -negative metastatic breast cancer.

Patients and methods: Patients were randomly assigned 2:1 to chemotherapy + bevacizumab or to chemotherapy + placebo. Before random assignment, investigators chose capecitabine, a taxane (paclitaxel, nab-paclitaxel, or docetaxel), gemcitabine, or vinorelbine. Dosing for bevacizumab or placebo was 15 mg/kg every 3 weeks or 10 mg/kg every 2 weeks, depending on chemotherapy regimen. The primary end point was progression-free survival (PFS). Secondary end points included overall survival, PFS by chemotherapy cohort, objective response rate (ORR), duration of objective response, 1-year survival rate, and safety.

Results: RIBBON-2 enrolled 684 patients (225, chemotherapy + placebo; 459, chemotherapy + bevacizumab). The combination of bevacizumab with chemotherapy demonstrated a statistically significant benefit. Median PFS increased from 5.1 to 7.2 months (stratified hazard ratio for PFS, 0.78; 95% CI, 0.64 to 0.93; P = .0072). The 10% improvement in ORR between the placebo- and bevacizumab-containing arms (39.5% v 29.6%; P = .0193), although not statistically significant, was consistent with previous trials. There was no statistically significant difference in overall survival. The most common grade ≥ 3 adverse events (AEs) related to bevacizumab treatment were hypertension (9.0%) and proteinuria (3.1%). There was an increased number of AEs leading to study discontinuation in the chemotherapy + bevacizumab arm compared with the chemotherapy + placebo arm (13.3% v 7.2%).

Conclusion: The combination of bevacizumab with commonly used chemotherapies improved PFS in the second-line treatment of patients with HER2-negative metastatic breast cancer, with a safety profile comparable with that in prior phase III studies.