In light of the need for new treatment options for postmenopausal, hormone receptor positive, HER2 negative women after failure of prior non-steroidal aromatase inhibitor (NSAI) therapy, the BOLERO-2 trial was performed and demonstrated significant efficacy of the combinatorial treatment of Everolimus and Exemestane compared to an Exemestane monotherapy in this setting.
In this randomized, double blind, placebo-controlled trial a statistically significant improvement in progression-free survival (PFS) by adding Everolimus to exemestane versus Exemestane alone was reported. Adding Everolimus determined a 2.4-fold prolongation in PFS from 3.2 up to 7.4 months and so lowered the risk of cancer progression by 56% for these women. These findings were confirmed by an independent assessment (4.1 vs. 11.0 months, risk reduction: 64%). The quality of life data shows positive trend in the Everolimus plus Exemestane treatment arm. (Baselga 2011, Hortobagyi 2011). Thus, the benefit of the combinatorial treatment versus Exemestane monotherapy was shown in a defined patient population under controlled conditions.
The primary objective of this trial to assess the Overall Response Rate (ORR) in postmenopausal women with hormone receptor positive breast cancer progressing following prior therapy with NSAIs treated with the combination of Everolimus and Exemestane. The secondary objectives include, Progression free survival (PFS), Overall survival (OS), Safety, Change in Quality of life scores over time, Health resource utilization. The exploratory objectives reflect scientific interest within the treatment of metastatic breast cancer and are to be modified, if applicable, according to the current scientific state of the art at the time of actual analysis. These include: the influence of age, performance status, cancer activity and inflammation on anxiety and depression; changes in serum bone-turnover biomarkers; Pharmacogenetics of Everolimus in patients with advanced breast cancer; presence and molecular characteristics of Circulating Tumor Cells; correlation of response to Exemestane/Everolimus with Proteomic analysis.
The present national, multi-center, open-label, single-arm study aims to evaluate the efficacy and safety, quality of life and health resources utilization of the combination of Everolimus and Exemestane in a broader patient population compared to BOLERO-2, i.e. without limitations as to the number of previous chemotherapy lines, the time point of progression after NSAI therapy, and the previous endocrine therapy as patients under Exemestane monotherapy may be enrolled. Since the combination was shown to significantly improve PFS in the previous BOLERO-2 trial, for ethical reasons no endocrine comparator drugs will be investigated in the present study, due to the low efficacy of Exemestane monotherapy (PFS 3.2 months).