Safety of everolimus plus exemestane in patients with hormone-receptor-positive, HER2-negative locally advanced or metastatic breast cancer: results of phase IIIb BALLET trial in Spain.

BACKGROUND: Everolimus with exemestane has shown promising activity in patients with hormone-receptor (HR)-positive HER2-negative endocrine-resistant advanced breast cancer. It is necessary, therefore, to characterize the safety profile of this new combination in the real-world clinical setting and in the broadest possible population. PATIENTS AND METHODS: Post-menopausal women with HR-positive HER2-negative advanced breast cancer progressing after prior non-steroidal aromatase inhibitors (NSAIs) were included. The objectives of this analysis were to evaluate the safety profile of this combination in a subset of Spanish patients in the BALLET trial and to characterize grade 3 and 4 adverse events (AEs) in routine clinical practice in Spain.
RESULTS: Between September 2012 and July 2013, 429 patients (20% of the overall study population) were included in the BALLET study in 52 hospitals in Spain, of whom 100 (23%) were ≥ 70 years. The median treatment duration was 3.14 and 3.03 months for exemestane and everolimus, respectively. The most common reasons for discontinuation of treatment were local reimbursement of everolimus (43%), followed by disease progression (31%) and the incidence of AEs (15%). The most frequent AEs causing permanent discontinuation were pneumonitis (4%), asthenia (2%) and stomatitis (2%). Overall, 87% of patients experienced at least one AE of any grade, 30% of patients at least one grade 3 AE and 2% of patients a grade 4 AE.
CONCLUSION: The safety profile in Spanish patients of the BALLET trial is consistent with the results obtained in the overall population of the trial, as well as in previous clinical trials.