monarchE: Abemaciclib (a CDK4/6 Inhibitor) + Hormone Therapy for the Adjuvant (Post-Surgery) Treatment of HR+ HER2- High Risk Early Stage Breast Cancer

The clinical trial monarchE assessed the benefit of combining the CDK4/6 inhibitor abemaciclib (a type of targeted therapy) with hormone therapy in comparison to hormone therapy alone.

monarchE consisted of a large group of women with HR+, HER2-, high risk early stage breast cancer.

The Trial:

Those participating in the clinical trial were randomly assigned either

-at least five years of adjuvant (post-surgery) hormone therapy combined with two years of abemaciclib

OR

-at least five years of adjuvant (post-surgery) hormone therapy on

Results:

This clinical trial demonstrated a significant invasive disease free survival benefit for those who received the abemaciclib along with hormone therapy. This means that there were more women in the group who took abemaciclib and hormone therapy who were cancer-free and healthy at the end of the trial (in comparison to the group of women who only took hormone therapy).

In conclusion, this clinical trial compared the standard of treatment (endocrine therapy only) for HR+ HER2- high risk early stage breast cancer with the new treatment combination (endocrine therapy and abemaciclib), and found that the new treatment combination was more effective.

monarchE not only shows the promising progress of the breast cancer research field, which is constantly growing and evolving through new drugs and combinations of drugs, but also the importance of phase III clinical trials, and their auspicious nature.

References: Breast Cancer Research Foundation. (2023). ASCO 2023: Updates from Major Breast Cancer Clinical Trials. https://www.bcrf.org/blog/bcrf-asco-2023-clinical-trials-news-updates/

ASCO Publications. (2024). Adjuvant Abemaciclib Plus Endocrine Therapy for Hormone Receptor–Positive, Human Epidermal Growth Factor Receptor 2–Negative, High-Risk Early Breast Cancer: Results From a Preplanned monarchE Overall Survival Interim Analysis, Including 5-Year Efficacy Outcomes. https://ascopubs.org/doi/10.1200/JCO.23.01994

National Library of Medicine. (2020). Abemaciclib Combined With Endocrine Therapy for the Adjuvant Treatment of HR+, HER2-, Node-Positive, High-Risk, Early Breast Cancer (monarchE). https://pubmed.ncbi.nlm.nih.gov/32954927/