postMONARCH

NCT05169567 📎

Regimen

Experimental
Abemaciclib 150 mg BID plus fulvestrant 500 mg.
Control
Placebo plus fulvestrant 500 mg.

Population

Women with HR+/HER2- advanced breast cancer who had progressed on a prior CDK4/6 inhibitor plus endocrine therapy; stratified by prior CDK4/6 agent and ESR1/PIK3CA status.

Key finding

postMONARCH showed that switching to abemaciclib plus fulvestrant after CDK4/6 progression provides a modest but significant PFS benefit over fulvestrant alone. Provides prospective phase 3 evidence supporting CDK4/6 switch strategies and is referenced in BINV-P discussions of post-CDK4/6 sequencing.

Source: PMID 39693591

Timeline

  • Publication: 2025 Mar 20

Guideline citations

  • NCCN BREAST