P1-14-04: Prolonged (≥1 Year) Exposure to First-Line Bevacizumab Combined with Paclitaxel in Patients with HER2−Negative Metastatic Breast Cancer Treated in a Routine Oncology Practice Study.

Abstract

Abstract Background: First-line bevacizumab (BEV) combined with weekly paclitaxel (PAC) significantly improves progression-free survival (PFS) and response rate (RR) vs PAC alone in HER2−negative metastatic breast cancer (mBC), as shown in E2100. The benefit of BEV combined with other chemotherapy (CT) agents was demonstrated in AVADO and RIBBON-1. BEV was continued for ≥1 year in 21% of patients in the global ATHENA safety study and in 42% of patients in the JO19901 single-arm Japanese study of BEV-PAC. We analyzed data from the subgroup of patients treated for ≥1 year in a German routine oncology practice study to provide insight into the safety and efficacy of prolonged first-line BEV-PAC. Methods: Patients who had received no prior CT for their mBC received BEV-PAC per the European label. Efficacy and safety were documented for up to 1 year (or until progression, death, or BEV discontinuation if earlier) with additional long-term follow-up. Data from patients treated with BEV for ≥1 year were extracted for this analysis. Results: By Jan 2011, data were available for 818 patients, of whom 157 (19%) had already received BEV for ≥1 year. Baseline characteristics of this subset relative to the overall population are summarized in the table. In 79% of those treated for ≥1 year, BEV was continued as a single agent after discontinuation of CT. The overall RR in patients treated for ≥1 year was 81% (complete response in 20%). Median PFS was 17.9 months (events in 44% of patients) vs 9.4 months in the overall population (events in 68%). Overall survival data are immature, as 81% of those treated for ≥1 year are still alive. The most common grade 3/4 adverse events in patients treated with BEV for ≥1 year were hypertension (11% of patients), pain (10%), and leukopenia (7%). There were no cases of gastrointestinal perforation, arterial thromboembolic event, or reversible posterior leukoencephalopathy syndrome in those treated for≥1 year. Analysis of adverse events according to time of onset is ongoing. Conclusions: A notable proportion of patients appear to derive benefit from prolonged exposure to first-line BEV-containing therapy. In the present analysis, baseline characteristics appeared more favorable in the subset of patients treated for ≥1 year than in the overall population. Efficacy data clearly have a bias towards improved outcome in those able to continue BEV for ≥1 year, as these patients had sustained disease control for ≥1 year. However, the efficacy of prolonged BEV-containing therapy is of interest and suggests that some patients achieve sustained disease control with continued first-line BEV-PAC with limited side effects. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-14-04.