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William J. Gradishar, MD, FACP, FASCO


ESMO 2023: 5-Year Data From monarchE Support Abemaciclib + Endocrine Therapy

By: Amy MacDonald, MS
Posted: Friday, October 27, 2023

Nadia Harbeck, MD, PhD, of Ludwig Maximilian University of Munich, presented 5-year outcome data from the landmark monarchE breast cancer trial during the European Society for Medical Oncology (ESMO) Congress 2023 (Abstract LBA17). The long-term data, which included an overall survival analysis, supported previous findings for the adjuvant use of the CDK4/6 inhibitor abemaciclib and endocrine therapy in patients with hormone receptor–positive, HER2-negative, early-stage breast cancer.

“At the pivotal 5-year mark for adjuvant early breast cancer trials, abemaciclib plus endocrine therapy continued to reduce the risk of developing invasive and distant disease recurrence well beyond the completion of treatment,” stated the investigators. “The Kaplan-Meier curves have continued to separate over time..., and the long-term safety profile is also very reassuring,” commented Carmen Criscitiello, MD, PhD, of the European Institute of Oncology, Milan, in an ESMO press release.

In monarchE, patients with hormone receptor–positive, HER2-negative breast cancer were randomly assigned to receive endocrine therapy (for at least 5 years) with or without abemaciclib for 2 years. Cohort 1 (n = 5,120) included patients with high risk, early-stage breast cancer with at least four positive axillary lymph nodes, one to three axillary lymph nodes with grade 3 disease, and/or tumors of at least 5 cm. Cohort 2 (n = 517) consisted of patients with one to three positive axillary lymph nodes and a central Ki67 index greater than 20%. Overall survival in the intent-to-treat population (cohorts 1 and 2) was assessed for statistical significance.

The 5-year results for the intent-to-treat population supported the benefit of abemaciclib-based therapy for patients with early-stage breast cancer for the endpoints of invasive disease–free survival (hazard ratio [HR] = 0.680, 95% confidence interval [CI] = 0.599–0.772) and distant relapse–free survival (HR = 0.675, 95%CI = 0.588–0.774).

Disclosure: For full disclosures of the study authors, visit

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