Impact of bevacizumab (BEV) on efficacy of second-line chemotherapy (CT) for triple-negative breast cancer (TNBC): Analysis of RIBBON-2.

Abstract

1010 Background: The efficacy of first-line BEV-containing therapy for metastatic breast cancer (MBC) has been proven in three randomized trials. BEV combined with CT resulted in longer progression-free survival (PFS, primary endpoint) and higher objective response rates (RRs) than with CT alone. In the second-line MBC setting, the RIBBON-2 trial demonstrated significantly improved PFS in patients (pts) receiving BEV combined with CT vs CT alone. We present a prespecified analysis of subgroup data in pts with TNBC. Methods: RIBBON-2 enrolled pts with MBC that had progressed on first-line non-BEV-containing CT. After CT was selected from a prespecified list (taxane, gemcitabine, capecitabine, or vinorelbine), pts were randomized 2:1 to receive CT with either BEV (10 mg/kg q2w or 15 mg/kg q3w) or placebo. Crossover to BEV at progression was permitted. The primary endpoint was PFS. Results: Of 684 pts treated in RIBBON-2, 159 (23%) had TNBC. Baseline characteristics were reasonably balanced in the two treatment groups. Baseline characteristics and efficacy results are summarized below. Conclusions: Pts with TNBC derive significant RR and PFS benefit from the combination of BEV with second-line CT. Despite the small sample size, there was a trend (HR 0.624; p=0.0534) towards OS benefit. Larger prospective randomized trials of BEV in TNBC are ongoing. Characteristic BEV + CT (n=112) Placebo + CT (n=47) Median age, years (range) 55 (28–86) 49 (33–79) Metastatic sites, % ≥3 48 32 Visceral, % 74 62 CT partner, % Taxane 42 43 Gemcitabine 23 28 Capecitabine 16 21 Vinorelbine 19 9 PFS Events, n (%) 94 (84) 42 (89) Median, months 6.0 2.7 HR* (95% CI) P value (log-rank) 0.494 (0.33–0.74) p=0.0006 OS Events, n (%) 52 (46) 29 (62) Median, months 17.9 12.6 HR*(95% CI) P value (log-rank) 0.624 (0.39–1.007) p=0.0534 1-year OS, % (95% CI) 63 (52–72) 50 (34–64) Difference in rates, % (95% CI) 13 (–6 to 31) p=0.1758 Objective RR, % (95% CI)* 41 (31–51) 18 (8–34) Difference, % (95% CI) P value* 23 (7–39) p=0.0078 * Stratified analysis (CT regimen and disease-free interval). Abbreviations: HR, hazard ratio; OS, overall survival.