Abemaciclib Plus Endocrine Therapy Improves PFS in HR-Positive, HER2-Negative Advanced Breast Cancer
Key Clinical Takeaways
- Design/Population: The AMBRE trial randomized 180 patients with untreated HR-positive, HER2-negative advanced breast cancer and high visceral tumor burden to receive abemaciclib plus endocrine therapy or physician’s choice chemotherapy. High visceral burden required ≥ 2 visceral sites, ≥3 lesions in one organ, or elevated LDH, and circulating tumor cells were assessed longitudinally.
- Key Outcomes: Abemaciclib plus endocrine therapy significantly improved progression-free survival compared with chemotherapy (13.9 vs 7 months; HR, 0.67). Duration of response also favored abemaciclib, while ORR, OS, and quality-of-life outcomes were similar between arms.
- Clinical Relevance: These findings support abemaciclib plus endocrine therapy as an effective first-line option for HR-positive, HER2-negative advanced breast cancer with high visceral tumor burden, a population often excluded from CDK4/6 inhibitor trials. Safety was consistent with expected profiles, and ongoing translational analyses may refine patient selection.
Veronique Dieras, MD, Eugene Marquis Center, Rennes, France, discusses findings from the phase 3 AMBRE trial evaluating abemaciclib plus endocrine therapy versus investigator’s-choice chemotherapy for patients with HR-positive, HER2-negative advanced breast cancer presenting with high visceral tumor burden.
The study demonstrated a significant progression-free survival advantage and longer duration of response with abemaciclib-based therapy, without new safety signals, in a population historically excluded from first-line CDK4/6 inhibitor trials.
These findings were presented at the 2025 San Antonio Breast Cancer Symposium in San Antonio, Texas.
Source:
Dieras V, Bidard FC, Roca L, et al. Primary results of Ambre, a randomized phase 3 comparing mono-chemotherapy (ct) vs abemaciclib + endocrine therapy (et) in hr+/her2- advanced breast cancer (abc) with high visceral tumor burden. Presented at SABCS 2025. December 9 - 12, 2025. San Antonio, Texas. Abstract RF7-06
