Exemestane and Everolimus combination treatment of hormone receptor positive, HER2 negative metastatic breast cancer: A retrospective study of 9 cancer centers in the Campania Region (Southern Italy) focused on activity, efficacy and safety

Exemestane (Exe) in combination with Everolimus (Eve) represents an important treatment option for patients diagnosed with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) metastatic breast cancer (MBC), which was previously treated with non-steroidal aromatase inhibitors (NSAI). Data from unselected populations may be useful for defining the optimal therapeutic algorithm within a clinical setting. Data from 264 HR+, HER2-MBC patients who received Exe-Eve treatment in combination, following the failure of NSAIs was retrospectively analyzed. Different lines of endocrine treatment (ET) were investigated to evaluate the efficacy and toxicity of the treatment within the 'everyday clinical practice' population. The disease control rate (DCR) was 73.1%, with no statistically significant difference among the different settings. At a median follow-up of 42 months, the median progression free survival (PFS) was 11.6, 9.7 and 7.5 months for patients treated with Exe-Eve as first, second or third line therapy, respectively. There was a statistically significant correlation with younger age, no previous adjuvant chemotherapy (CT), no previous adjuvant endocrine therapy (ET), HT duration ≥36 months, involvement of liver and/or lung, no prior CT for metastatic disease and PS=0 at the start of treatment. The median overall survival (OS) was 33.0 months; at a median follow-up of 67 months, the median OS was 43.1, 31.7 and 27.9 months in patients treated with Exe-Eve in first, second or third line therapy, respectively. On multivariate analysis, diabetes and previous CT for metastatic disease were revealed to correlate with a worse outcome. Conversely, the presence of mucositis was significantly associated with long-term survival. Overall, Exe-Eve was typically well tolerated and the majority toxicities were G1 or 2, while treatment discontinuation due to unacceptable toxicity was only required in 5.7% of patients. Despite the limitations due to the observational nature of this study, the findings suggest that treatment with Exe-Eve is an active and safe therapeutic option for endocrine-sensitive MBC patients in a real-world clinical setting, regardless of treatment lines.