Avutometinib, Abemaciclib, and Fulvestrant in Patients with HR+/HER2- Metastatic Breast Cancer Previously Treated with CDK4/6 Inhibitor: A Single-Arm Phase I Trial.
Clin Cancer ResOct 1, 2026
Adrienne G Waks, Elia Segui, Tianyu Li et al.
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In 30 seconds
This single-arm phase I trial evaluated the combination of avutometinib, abemaciclib, and fulvestrant in 16 patients with HR+/HER2- metastatic breast cancer who had previously progressed on CDK4/6 inhibitors. The maximum tolerated dose was established, and the regimen demonstrated a 13% overall response rate and a median progression-free survival of 3.6 months.
Key findings
- Maximum tolerated dose was abemaciclib 100 mg twice daily and avutometinib 3.2 mg twice weekly.
- Overall response rate was 13% (2/15 patients with measurable disease).
- 24-week clinical benefit rate was 40% (6/15 patients with measurable disease).
- Median progression-free survival was 3.6 months (95% CI, 2.1-not reached).
Why it matters
The study addresses treatment options for patients with HR+/HER2- metastatic breast cancer who have developed resistance to CDK4/6 inhibitors, highlighting a potential new therapeutic strategy that may improve outcomes in this challenging population.