FDA Approves Lilly's Inluriyo (Imlunestrant) for ESR1-Mutant Advanced Breast Cancer

INDIANAPOLIS, September 25, 2025 – Eli Lilly and Company (NYSE: LLY) today announced that the U.S. Food and Drug Administration (FDA) has approved Inluriyo (imlunestrant), an oral estrogen receptor antagonist, for the treatment of adults with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2–), ESR1-mutant advanced or metastatic breast cancer (MBC). The indication is for patients whose disease has progressed after at least one line of endocrine therapy.

The approval is supported by data from the pivotal Phase 3 EMBER-3 trial. Inluriyo demonstrated a statistically significant 38% reduction in the risk of disease progression or death compared to standard endocrine therapy. In patients with ESR1 mutations, the median progression-free survival (PFS) was 5.5 months with Inluriyo versus 3.8 months with investigator’s choice (fulvestrant or exemestane) (HR=0.62 [95% CI: 0.46-0.82]; p=0.0008).

ESR1 mutations can lead to constitutively active estrogen receptors that drive tumor growth. Inluriyo works by binding to, blocking, and promoting the degradation of these receptors. It offers a convenient once-daily oral dosing schedule.

Jacob Van Naarden, Executive Vice President and President of Lilly Oncology, stated, "This approval represents a significant step forward in our mission to deliver innovative, all-oral treatment options for breast cancer patients."

The prescribing information includes warnings regarding embryo-fetal toxicity. Common adverse reactions (≥10%) include decreased hemoglobin, musculoskeletal pain, decreased calcium, increased AST, fatigue, and diarrhea. Most events were Grade 1-2.

Lilly is also investigating imlunestrant in the Phase 3 EMBER-4 trial for early-stage breast cancer adjuvant therapy.