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 (=0.002; hazard ratio [HR] =1.8) and OS (=0.009; HR=2.0), while patients not previously treated with taxanes had longer OS (<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.