Everolimus plus exemestane in hormone-receptor-positive, HER2-negative locally advanced or metastatic breast cancer: incidence and time course of adverse events in the phase IIIb BALLET population

Background: The addition of everolimus to exemestane therapy significantly improves progression-free survival in postmenopausal patients with hormone-receptor (HR)-positive HER2-negative endocrine-resistant breast cancer. However, the safety profile of this schedule still might be optimized. Methods: Patients included in the BALLET trial were assessed. The objectives of this analysis were to provide additional information on the safety profile of this schedule depending on prior anticancer therapies and to characterize the time course of adverse events (AEs) and serious AEs (SAEs) of clinical interest throughout the study period. Non-infectious pneumonitis (NIP), stomatitis, asthenia and weight loss were selected as AEs of clinical interest. Results: The safety population of this analysis comprised 2131 patients. There were similar incidences of AEs and SAEs of clinical interest regardless of previous anticancer therapies. Most stomatitis and asthenia events occurred within the first three months. Incidence of weight loss appeared to plateau except in the case of grade 3–4 events, which occurred rarely. The incidence of any grade NIP (between 2 to 6%) and grade 3–4 NIP (between 0 to 1%) was low across the study, but steady. Conclusions: Everolimus plus exemestane is a well-known therapeutic option for aromatase inhibitor pretreated advanced breast cancer patients, and its toxicity profile is similar to that described in previous studies. Close monitoring, especially within the first three months, early intervention with preventive measures and patient education to help recognize the first signs and symptoms of AEs, will help to reduce their incidence and severity.