EMBER-3 — Imlunestrant With or Without Abemaciclib vs Standard Endocrine Therapy in ER-Positive Advanced Breast Cancer

Phase 3 · 2024 · Breast Cancer

Design

Randomized phase 3 comparing imlunestrant vs investigator's choice standard endocrine therapy, and imlunestrant + abemaciclib vs imlunestrant alone.

Population

ER-positive, HER2-negative advanced breast cancer that progressed on prior endocrine therapy (with or without a CDK4/6 inhibitor); ESR1-mutant subgroup prespecified.

Primary Endpoint

progression-free survival (PFS)

Key Result

In ESR1-mutant disease, imlunestrant PFS 5.5 vs 3.8 mo with standard endocrine therapy (HR 0.62); imlunestrant + abemaciclib PFS 9.4 vs 5.5 mo vs imlunestrant alone (HR 0.57).

Guideline Impact

Endocrine-resistant ER-positive advanced breast cancer