BOLERO-2, an international, phase III study in patients with locally advanced or metastatic breast cancer refractory to non-steroidal aromatase inhibitor therapy, previously reported that the addition of everolimus (EVE) to exemestane (EXE) significantly improved progression-free survival (PFS) (6.9 versus 2.8 months; HR = 0.43; P < 0.001) versus EXE alone by local assessment (Baselga J, et al. N Eng J Med 2011). This report presents data from the Japanese subpopulation.Methods
Eligible patients were randomized (2:1) to EVE (10 mg/day) or matching placebo (PBO), with both arms receiving EXE (25 mg/day). Treatment was continued until disease progression, unacceptable toxicity, or withdrawal of consent. The primary end point was PFS by local assessment. Secondary end points included overall survival (OS), objective response rate (ORR), clinical benefit rate (CBR), and safety.Results
Of the 724 patients from 24 countries enrolled in this study, 106 patients were Japanese, of whom 71 and 35 were assigned to EVE + EXE or PBO + EXE, respectively. Data from this Japanese subpopulation are presented. The addition of EVE to EXE prolonged median PFS (8.4 months versus 4.1 months; P = 0.025), increased ORR (16.9% versus 0%), and CBR (43.7% versus 25.7%) compared with EXE alone. In the EVE + EXE arm, most common grade 3/4 adverse events included stomatitis (9.9%), anemia (5.6%), and aspartate aminotransferase increased (4.2%). The incidence of non-infective lung-related adverse events was 31.0%, which was higher than in the overall population. The majority of these events were grade 1 or 2. Most patients showed recovery or relief after dose reduction or interruption, administration of corticosteroids, or oxygen therapy.Conclusion
Japanese patients in the BOLERO-2 trial treated with EVE + EXE showed similar PFS benefits as the overall population and a manageable safety profile. Thus, EVE + EXE is a promising new therapeutic option for Japanese women with advanced breast cancer.