(ChemotherapyAdvisor) – Adding everolimus to exemestane significantly improved progression-free survival (PFS) in women with hormone-receptor–positive advanced breast cancer previously treated with nonsteroidal aromatase inhibitors, the BOLERO-2 study concluded in the February 9 issue* of the New England Journal of Medicine.
The Phase 3 international Breast Cancer Trials of Oral Everolimus-2 (BOLERO-2) randomized 724 patients to exemestane plus the mTOR inhibitor everolimus or exemestane plus placebo. Median age was 62 years and 84% of patients had hormone-sensitive disease. Previous therapy included letrozole or anastrozole (100%), tamoxifen (48%), fulvestrant (16%), and chemotherapy (68%).
Observed PFS, the primary end point, was a median of 6.9 months for the exemestane and everolimus group and 2.8 months for those who received exemestane alone, corresponding to a 57% reduction in the hazard ratio (P<0.001).
A higher incidence of adverse events occurred in the combination-therapy group consistent with those reported with everolimus and other rapamycin analogs: stomatitis, fatigue and asthenia, diarrhea, cough, pyrexia, and hyperglycemia. Lack of tolerability of everolimus led to a high percentage of patients discontinuing everolimus.
“The potential of everolimus to benefit patient survival is not yet known,” the investigators concluded.
*Originally published online December 7, 2011 and updated on December 13, 2011.