Study Announcement
THURSDAY, Oct. 23, 2025 -- A study published online Oct. 17 in the Annals of Oncology (coinciding with the annual meeting of the European Society for Medical Oncology, held from Oct. 17 to 21 in Berlin) shows that for patients with hormone receptor (HR)-positive, human epidermal growth factor 2 (HER2)-negative, node-positive, high-risk early breast cancer (EBC), adjuvant abemaciclib combined with endocrine therapy (ET) yields significantly improved overall survival (OS) compared with ET alone.
Study Design
Stephen Johnston, Ph.D., from the Royal Marsden NHS Foundation Trust in London, and colleagues reported the primary OS results of a trial involving patients with HR-positive, HER2-negative, node-positive, high-risk EBC. All patients received ET for at least five years, with or without abemaciclib for two years.
A total of 5,637 patients were randomized: 2,808 in the abemaciclib-ET group and 2,829 in the ET alone group.
Key Study Results
Overall Survival (OS): With a median follow-up of 76.2 months, the abemaciclib-ET group had a 15.8% lower risk of death than the ET alone group (hazard ratio, 0.842), meeting the prespecified significance boundary.
Seven-Year OS Rate: 86.8% in the abemaciclib-ET group versus 85.0% in the ET alone group.
Subgroup Analysis: Consistent OS benefit was observed across all prespecified subgroups.
Metastatic Disease: Fewer patients in the abemaciclib-ET group had metastatic disease (6.4%) compared with the ET alone group (9.4%).
Other Endpoints: Sustained improvements were seen in invasive disease-free survival and distant relapse-free survival (hazard ratios, 0.734 and 0.746, respectively).
Safety: Long-term safety data did not raise concerns about delayed toxicities.
Expert Statement
"For patients, survival is what matters most -- and abemaciclib plus ET represents the first contemporary medicine in over two decades to deliver a clear improvement in overall survival in the adjuvant setting," Johnston said in a statement.
