Prior chemotherapy did not increase the rate of adverse events (AEs) among patients with metastatic estrogen receptor (ER)-positive breast cancer treated with everolimus plus exemestane, according to a post hoc analysis published in The Oncologist.1

Everolimus plus exemestane was previously demonstrated to be an effective second-line therapy for patients with ER-positive breast cancer who progressed after treatment with a nonsteroidal aromatase inhibitor. The European BALLET study was an open-label expanded-access study that provided the combination for second-line therapy of postmenopausal women with locally advanced or metastatic disease.

The purpose of this post hoc analysis of the BALLET study was to determine if cumulative toxicities were present in an Italian cohort with metastatic disease as a result of prior chemotherapy.

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The analysis included 1151 of the 2131 enrolled patients who had a median age of 64. The Eastern Cooperative Oncology Group performance status was 0 among 71.9%, 1 among 25.6%, and 2 among 1.7%. Metastatic disease was present in 84% of patients.

The median duration of treatment was 139.5 days with exemestane and 135.0 days with everolimus. Nearly all patients (99.8%) received 10 mg of everolimus for a mean 113.7 days.

At least 1 serious adverse event (SAE) occurred in 18.2% of patients, and 13.5% of patients discontinued everolimus or exemestane as a result of an SAE.

Prior chemotherapy was associated with a trend of a greater rate of mortality, SAEs, and AEs causing treatment discontinuation compared with no prior chemotherapy, though these findings were not significant.

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The authors concluded that the findings from this analysis “showed that previous chemotherapy did not affect the safety profile of the combination regimen based on everolimus and exemestane.” These data were consistent with the overall BALLET results.


  1. Generali D, Montemurro F, Bordonaro R, et al. Everolimus plus exemestane in advanced breast cancer: safety results of the BALLET study on patients previously treated without and with chemotherapy in the metastatic setting. Oncologist. 2017 Apr 21. doi: 10.1634/theoncologist.2016-0461 [Epub ahead of print]