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

Andrés Redondo,1 Manuel Ramos Vázquez,2 Luis Manso,3 Miguel J Gil Gil,4 Isabel Garau Llinas,5 Elisa García-Garre,6 César A Rodríguez,7 José Ignacio Chacón,8 Guillermo López-Vivanco9 1Clinical Oncology Department, Hospital Universitario La Paz, Madrid, Spain; 2Centro Oncológico de Galicia, A Coruña, Spain; 3Medical Oncology Service, Hospital Universitario 12 de Octubre, Madrid, Spain; 4Institut Catala d’Oncologia – L’Hospitalet, Barcelona, Spain; 5Hospital Son Llatzer, Palma de Mallorca, Spain; 6Hematology and Medical Oncology Department, University Hospital Morales Meseguer, Murcia, Spain; 7Oncology Department, Hospital Universitario de Salamanca-IBSAL, Salamanca, Spain; 8Medical Oncology Department, Hospital Virgen de la Salud, Toledo, Spain; 9Department of Medical Oncology, Hospital Universitario Cruces, Barakaldo, Spain 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. Keywords: bevacizumab, metastatic breast cancer, real-world, maintenance hormonal therapy, taxan