An analysis of the monarchE trial evaluated the prognostic and predictive value of the Ki-67 index before and after neoadjuvant chemotherapy (NAC) in patients with hormone receptor-positive, HER2-negative, node-positive, high-risk early breast cancer. The study found that changes in Ki-67 levels following NAC were associated with outcomes in patients treated with adjuvant abemaciclib plus endocrine therapy.
Patients with a high Ki-67 index (β₯20%) after NAC derived greater benefit from abemaciclib, with improved invasive disease-free survival compared to endocrine therapy alone. Those with low Ki-67 (<20%) showed less pronounced benefit. The findings suggest Ki-67 dynamics can help identify patients most likely to respond to abemaciclib.
The monarchE trial previously demonstrated that two years of adjuvant abemaciclib plus endocrine therapy improved invasive disease-free survival over endocrine therapy alone in this high-risk population. This new analysis highlights the importance of biomarker assessment in treatment decisions.
Researchers emphasized that Ki-67 is a validated prognostic marker, but its predictive value for abemaciclib requires further validation. The study was presented at a recent oncology conference and supports personalized treatment approaches in early breast cancer.
