Safety analysis, association with response and previous treatments of everolimus and exemestane in 181 metastatic breast cancer patients. A multicenter Italian experience

Purpose The everolimus and exemestane combination represents a treatment option for the endocrine sensitive metastatic breast cancer (MBC) patients. The toxicity profile reported in the Bolero 2 trial showed the feasibility in the selected patients. Few data are available for the unselected population. Methods In order to evaluate the safety in the unselected population of the clinical practice and to evaluate a possible association of toxicities with previous treatments, clinical data from 181 consecutive patients were retrospectively collected. Results Due to toxic events, everolimus dosage was reduced to 5 mg in 27% of patients. No association was found in the analysis between toxicity and number of prior therapies, neither between toxicity and response. In the multivariate analysis the previous exposure to anthracyclines for advanced disease represents the only predictive factor of developing grade ≥2 toxicity (OR = 2.85 CI 95% 1.07–7.59, p = 0.036). Conclusions The association of everolimus and exemestane has confirmed to be a safe and effective treatment for endocrine sensitive MBC patients even in routine clinical practice. The rate of treatment discontinuation due to toxicity is low and none association between previous number of treatments and response or between toxicity and response was found.