Long-term response to first-line bevacizumab-based therapy in patients with metastatic breast cancer: results of the observational “LORENA” study

Background Randomized controlled trials of the first-line combination of bevacizumab and chemotherapy in patients with metastatic breast cancer (MBC) have shown improvements in tumor response and progression-free survival (PFS). Objective The aim of this ambispective, observational study (LORENA) was to describe the clinical characteristics of long-term responders to bevacizumab-based therapy. Patients and methods This study consisted of a retrospective and a prospective phase. During the retrospective phase, patients with HER2-negative MBC who were treated with bevacizumab-based first-line therapy were included. During the prospective phase, patients with PFS of ≥12 months were treated according to routine clinical practice procedures. Overall survival (OS) and PFS were estimated using the Kaplan–Meier method. Univariate and multivariate analyses of prognostic factors were performed. Results In total, 148 women were included (median age: 50 years; range: 29–81 years). The mean duration of exposure to bevacizumab was 18 months. The majority of patients experienced objective response (complete: 23%; partial: 57%). Median PFS was 22.7 months and median OS was 58.2 months. In multivariate analyses, patients receiving maintenance hormonal therapy (MHT) had longer PFS (P=0.002; hazard ratio [HR] =1.8) and OS (P=0.009; HR=2.0), while patients not previously treated with taxanes had longer OS (P<0.0001; HR =3.3). No unexpected adverse events were observed. Conclusion The results of this study suggest, that among long-term responders, first-line bevacizumab-based therapy is more effective in patients who had not been previously treated with taxanes, and that MHT provides additional therapeutic benefits by extending PFS and OS.