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William J. Gradishar, MD, FACP, FASCO


ASCO 2023: Use of Abemaciclib Plus Endocrine Therapy by Age Subgroups With High-Risk, Early-Stage Breast Cancer

By: Jenna Carter, PhD
Posted: Monday, June 12, 2023

A study presented at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 501) reported findings on the efficacy and safety of the use of adjuvant abemaciclib (a CDK4/6 inhibitor) combined with endocrine therapy in older patients with hormone receptor–positive, HER2-negative, node-positive, high-risk, early-stage breast cancer stratified by age. Erika P. Hamilton, MD, of the Sarah Cannon Research Institute, Nashville, and colleagues examined the survival outcomes of patients who received abemaciclib plus endocrine therapy versus endocrine therapy alone. Their findings revealed that patients aged 65 or older as well as those younger than age 65 had similar invasive disease–free survival rates in both drug groups tested, although older patients had higher rates of adverse events and treatment discontinuation.

A total of 4,787 patients younger than age 65 and 850 patients aged 65 or older were included in the monarchE trial. Patients were randomly assigned (1:1) to receive endocrine therapy for up to 10 years plus or minus abemaciclib. Distant relapse–free survival and efficacy in invasive disease–free survival was assessed in the intent-to-treat population by the prespecified age groups of younger than age 65 and aged 65 or older. Safety was also evaluated among older patients in two subgroups: those between age 65 and 74 and those aged 75 or older.

Invasive disease–free survival at 42 months of follow-up was similar in both the younger than 65 (270 vs. 414 events; hazard ratio [HR] = 0.646, 95% confidence interval [CI] = 0.554–0.753) and 65 and older (66 vs. 85 events; HR = 0.767, 95% CI = 0.556–1.059) groups for abemaciclib plus endocrine therapy versus endocrine therapy alone. Patients aged 65 or older had ~ 5% higher incidence of ≥ grade 3 adverse events compared with younger patients, mainly diarrhea and fatigue. Additionally, serious adverse events, treatment discontinuations, and dose reductions were more common in older patients.

Disclosure: For full disclosures of the study authors visit,

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