Abemaciclib Plus Endocrine Therapy Under Study in Advanced Breast Cancer

By: Joshua D. Madera, MD
Posted: Thursday, October 24, 2024

For patients with hormone receptor (HR)-positive, HER2-negative advanced breast cancer, the use of a combined therapeutic approach with the CDK4/6 inhibitor abemaciclib and endocrine therapy may improve clinical outcomes, according to the results of the phase II ABIGAIL trial, presented at the European Society for Medical Oncology (ESMO) Congress 2024 (Abstract LBA23). Compared with patients who received paclitaxel, those given the combination of abemaciclib and endocrine therapy demonstrated an improved overall response rate, explained Juan de la Haba Rodriguez, MD, of Reina Sofía University Hospital, Córdoba, Spain, and colleagues.

From 2021 to 2024, a total of 162 patients with HR-positive, HER2-negative advanced breast cancer were recruited for the study. All patients were treatment-naive. To be included in the study, patients were required to have at least one criterion of aggressive disease, which included visceral metastases, lactate dehydrogenase value greater than 1.5 times the upper limit of normal, a primary tumor with grade 3 or negative progesterone receptors, or evidence of disease progression within 36 months after completing adjuvant endocrine therapy. Eligible patients were randomly assigned to receive abemaciclib plus letrozole or fulvestrant (n = 80) or paclitaxel followed by abemaciclib plus letrozole or fulvestrant (n = 82).

The study authors identified evidence of visceral disease in 64% of patients. At least three metastatic sites were observed in 36% of patients, and de novo advanced breast cancer was reported in 30% of patients. Additionally, abemaciclib plus letrozole or fulvestrant yielded an improved overall response rate (59%) compared with paclitaxel followed by abemaciclib plus letrozole or fulvestrant (40%, odds ratio = 2.12).

Disclosure: Dr. Rodriguez reported no conflicts of interest. For full disclosures of the other study authors, visit cslide.ctimettingtech.com.

ESMO Congress 2024

---