Long-term responders to first-line bevacizumab-based therapy in metastatic breast cancer (MBC) patients: Results of the observational study LORENA.

Abstract

e12563 Background: Randomized controlled trials in MBC patients evaluating bevacizumab as first-line treatment showed improvements in tumor response and progression-free survival (PFS) when added to chemotherapy. The aim of the LORENA study was to describe the clinical features, prognosis factors and safety of bevacizumab and chemotherapy treatment for MBC in routine practice. Methods: Observational, multicentre, ambispective study conducted in Spain. The study had a retrospective and a prospective phase. Data were obtained from March 2012 to October 2013. In the retrospective phase, eligible patients were women with metastatic or locally-advanced breast cancer, treated with bevacizumab as a first-line therapy, and progression-free survival for ≥ 12 months. In the prospective phase, patients were followed-up and assessed as per routine clinical practice. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method. Univariate and multivariate analyses of prognostic factors were performed. Results: 148 women from 38 centers were included. The mean age was 52 (±11) years. Bone, lung and liver were the most frequent metastasis sites. 138 patients were HER2-neg. on diagnosis (data unknown in 10 patients). The mean exposure to bevacizumab was 18 (±11) months. Most patients had objective response, 23% complete response, and 57% partial response. Median OS was 58.2 months and median PFS was 22.7 months. In multivariate analyses, OS was higher in patients with hormonal maintenance therapy (HMT) (p = 0.009; HR = 2.0) and in patients not treated with taxanes before the metastatic diagnosis (p < 0.0001; HR = 3.3); also, PFS was higher in patients with HMT (p = 0.002; HR = 1.8). No adverse events were observed other than those reported previously. Conclusions: Outcomes of OS and PFS suggest a benefit from bevacizumab maintained therapy. HMT was a PFS prognosis factor. HMT and not having been treated with taxanes before the metastatic diagnosis were two independent OS prognosis factors. Our results could provide further evidence supporting the use of bevacizumab as maintenance therapy for MBC patients.