[BOLERO -- another remarkable step in treatment of breast cancer]

Area of Science:

• Oncology
• Pharmacology
• Molecular Genetics

Background:

• Targeted therapy is a cornerstone of modern cancer treatment, with specific agents available for breast cancer.
• Despite advancements, there is a critical need for novel, effective molecules to treat resistant cancer subgroups and enhance existing therapies.
• Everolimus, an mTOR inhibitor, has demonstrated efficacy and is approved for hormone receptor-positive breast cancer.

Purpose of the Study:

• To review and summarize the clinical trial data for everolimus in breast cancer treatment.
• To evaluate the efficacy of everolimus in combination with established therapies based on published Phase 3 trial results.

Main Methods:

• Analysis of two Phase 3 clinical trials: BOLERO-2 (exemestane +/- everolimus) and BOLERO-3 (trastuzumab/vinorelbine +/- everolimus).
• Assessment of progression-free survival (PFS) as a primary endpoint and overall survival (OS) as a secondary endpoint.

Main Results:

• Both BOLERO-2 and BOLERO-3 trials demonstrated a statistically significant improvement in progression-free survival (PFS) in the arms treated with everolimus.
• In the BOLERO-2 trial, a 4.4-month improvement in overall survival (OS) was observed in the everolimus arm, though it did not reach statistical significance.
• Currently, no reliable biomarkers exist to predict which breast cancer patients will benefit most from everolimus therapy.

Conclusions:

• Everolimus, when added to standard treatments like exemestane or chemotherapy, significantly extends progression-free survival in certain breast cancer patient populations.
• While overall survival data suggest a clinical benefit, further investigation is warranted.
• The identification of predictive biomarkers for everolimus response remains a critical unmet need in optimizing its use in breast cancer therapy.