Long-term responders to first-line bevacizumab-based therapy among patients (pts) with HER2-negative metastatic breast cancer (MBC): Retrospective results of an ambispective observational study.

e12558 Background: LORENA is an ambispective observational study evaluating B-based therapy in a real world setting which purpose is to assess clinical features, treatments and prognosis of HER2-negative MBC pts with ≥12 months (mo.) of PFS to 1 st -line B-based chemotherapy (CT). Methods: Pts with MBC receiving 1 st -line CT and B are enrolled. No prespecified schedules, doses or assessments. Data since the introduction of the treatment with B were collected at inclusion (retrospective phase), and prospectively at 18 mo. after enrollment for the patients alive at the time of inclusion, including B-targeted adverse events (AEs). Relevant baseline and on-study variables were analyzed by Cox model to identify independent effects on PFS. Results: By Jan 2013, complete retrospective data were available for 84 pts, 33 (39.3%) of them having stage III-IV at diagnosis. Median age, 50 years (r: 29–77); age ≥65 years, 13%; triple negative, 20.2%; bone/liver/lung metastases (%), 55/27/40; ≥2 metastases sites: 46.4%; ECOG status 0-1: 91.7%, ≥2: 5.9%, UK: 2.3%. 67% of pts have received prior (neo)adjuvant CT, with 56 and 30% of them with anthracyclines and taxanes, respectively. The objective response was 78%, including complete responses in 23%. A further 22% had stable disease. Median duration of B-based therapy was 12.4 mo. PFS events had been recorded in 44% of pts. Median PFS: 19.5 mo. (95%CI: 15.6-23.2). Cox proportional hazard multivariate regression model showed that B-based therapy ≥15 vs <15 mo was associated with improved PFS (26.5 vs 14.0 mo, p= 0.009; HR 0.40 [95%CI: 0.19-0.81]). The most common grade ≥3 B-related AEs were: Hypertension 9.5%, proteinuria 3.5%, bleeding 3.5%, and thromboembolic events 1.1%. No B-related death was reported. Conclusions: Outcomes in routine oncology practice for LORENA patients are consistent with those from prospective trials of 1st-line B-containing therapy and ATHENA study. These results suggest a benefit from a maintained VEGF suppression and that B continuation either as a single agent or combined with CT, until disease progression is recommended. Follow-up is ongoing.