Characterization of patients who received prior chemotherapy for advanced breast cancer (ABC) in BOLERO-2.

Abstract

151 Background: In patients with hormone receptor–positive (HR+) breast cancer, endocrine therapy is the standard of care both in the adjuvant setting and as front-line therapy for ABC. Chemotherapy (CT) is commonly used for HR+ ABC patients if disease burden is high and rapid symptom control is required (Barrios CH. GAMO. 2010). In the phase III BOLERO-2 study (NCT00863655), first-line of prior CT in the ABC setting was allowed. This subset analysis examined disease characteristics and the efficacy of everolimus (EVE) + exemestane (EXE) in patients who received CT for ABC prior to BOLERO-2 study entry. Methods: In BOLERO-2, 724 patients with HR+, human epidermal growth factor receptor 2–negative (HER2–) ABC whose disease recurred or progressed during/after a nonsteroidal aromatase inhibitor were randomized 2:1 to EVE (10 mg/d) + EXE (25 mg/d) or placebo (PBO) + EXE. The primary endpoint was progression-free survival (PFS) by local investigator review (confirmed by blinded independent central review). Results: A total of 186 patients (26%) received prior CT for ABC (125 in the EVE + EXE group and 61 in PBO + EXE). In this subset, 54% (67 of 125) of EVE+ EXE patients received prior CT in the advanced setting only while 46% (58 of 125) of EVE + EXE patients received prior CT in both the neoadjuvant/adjuvant and advanced settings. Visceral metastases (67% vs. 56%), multiple metastases (79% vs. 66%), and ≥ 4 metastatic sites (18% vs. 15%) were more frequent in ABC patients with prior CT for ABC at study entry compared with those with no prior CT for ABC. History of disease recurrence <6 months from initial diagnosis was recorded in 32% (n = 60) of prior CT patients versus 17% (n = 93) of patients with no prior CT. Median PFS (by local assessment) in patients who received prior CT for ABC was substantially longer with EVE + EXE versus PBO + EXE (6.1 vs. 2.7 mo; hazard ratio = 0.38; 95% CI, 0.27-0.53). PFS by central review showed similar results (7.1 vs. 2.8 mo, respectively; hazard ratio = 0.42; 95% CI, 0.27-0.65). Conclusions: These results demonstrate that patients with HR+, HER2 ABC who received previous CT in the advanced setting had a higher tumor burden but derived significant and clinically meaningful benefit from combination therapy with EVE + EXE. Clinical trial information: NCT00863655.