Everolimus Plus Exemestane vs Monotherapy for ER+ HER2- Advanced Breast Cancer

MedicalResearch.com Interview with:

Guy Jerusalem, MD, PhD CHU Sart Tilman Liege and Liege University Liege, Belgium

Dr. Jerusalem

Dr. Guy Jerusalem, MD, PhD
CHU Sart Tilman Liege and Liege University
Liege, Belgium

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: BOLERO-6 was conducted to fulfill postapproval regulatory commitments to the FDA and EMA to estimate treatment benefit with EVE + EXE vs EVE alone or CAP for ER+, HER2− ABC that had progressed on an NSAI. Everolimus plus exemestane has not previously been compared with everolimus alone or capecitabine in a randomized setting.Data describing everolimus alone are limited to a single phase 2 study of just 19 patients. Thus, the FDA deemed it important to ascertain the efficacy of everolimus alone for ER+ breast cancer, and to determine the contribution of exemestane to combination therapy with everolimus. Capecitabine is often the first chemotherapeutic agent given for ER+ breast cancer that has progressed on anti-estrogen therapy. It has a reported PFS of 4.1–7.9 months among patients with HER2-negative advanced breast cancer. However, it has a different safety profile to everolimus or exemestane, and a comparison of endocrine-based combination therapy with single-agent chemotherapy was yet to be conducted.

The median PFS with EVE + EXE (8.4 months) was consistent with BOLERO-2 (7.8 months), and compared to EVE alone here (6.8 months) corresponded to an estimated 26% reduction of risk of disease progression or death (HR 0.74).

A numerical median PFS difference was observed for CAP over EVE + EXE (9.6 vs 8.4 months), which may be attributed to various baseline characteristics favoring CAP and potential informative censoring. The median PFS with capacitabine was longer than expected based on previous trials. Interpretation of the results of BOLERO-6 must consider the limited sample size and open-label design. 

MedicalResearch.com: What should readers take away from your report?

Response: The trial does not change the management of our patients today. The international guidelines recommend an endocrine therapy based approach for ER positive HER2 negative advanced breast cancer except in the case of extensive visceral disease (visceral crisis). Chemotherapy is only recommended after failure of several lines of endocrine therapy outside of this specific situation. The numerically longer median PFS seen with capecitabine (9.6 months) versus everolimus plus exemestane (8.4 months) should be interpreted cautiously as BOLERO-6 was designed to provide estimates of treatment effect only, and not powered to perform statistical comparisons. Median PFS and safety with everolimus plus exemestane in this study were consistent with the BOLERO-2 study and other real-world evidence. As the benefit–risk profile is unchanged, everolimus plus exemestane remains an important and approved option for patients with advanced breast cancer around the world.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Response: A difference in efficacy between everolimus plus exemestane and capecitabine is still uncertain. Only a well powered phase 3 trial can answer this question or the more general question how a targeted agent combined with endocrine therapy performs compared to chemotherapy. Some data are expected in the near future concerning the CDK4/6 inhibitor palbociclib + endocrine therapy compared to capecitabine


Jerusalem G, de Boer RH, Hurvitz S, et al. Everolimus Plus Exemestane vs Everolimus or Capecitabine Monotherapy for Estrogen Receptor–Positive, HER2-Negative Advanced Breast CancerThe BOLERO-6 Randomized Clinical Trial. JAMA Oncol. Published online June 03, 2018. doi:10.1001/jamaoncol.2018.2262

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