EMBER-3 is a Phase 3 trial of imlunestrant (Inluriyo), a next-generation oral SERD, in ER-positive/HER2-negative advanced breast cancer after prior endocrine therapy. In the ESR1-mutant population, imlunestrant improved median PFS to 5.5 vs 3.8 months (HR 0.62; p=0.0008), supporting FDA approval on September 25, 2025 with the Guardant360 CDx. Sponsor: Eli Lilly. On September 18, 2026, the FDA additionally approved imlunestrant plus abemaciclib in the ESR1-mutated population (PFS 11.1 vs 5.5 months, HR 0.53) — the combination approval.
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Ok- now we are up to 4 options in ESR1m 2nd line MBC: Elacestrant Imlunestrant Imlunestrant + abema Vepdegestrant Great to have a combo option! https://t.co/P9JavZNzVd
Imlunestrant-abema now FDA-approved for pretreated patients with ESR1m HR+/HER2- MBC, representing the first approval of an oral SERD combination in this setting. For which 2L patients with ESR1 mutations will you favor this combination?
FDA approved #imlunestrant + #abemaciclib for ESR1-mutated ER+/HER2− MBC at progression on endocrine therapy, based on #EMBER3. The control arm was imlunestrant alone. In an exploratory ESR1m subgroup, PFS was 11.1 vs 5.5 mo (HR 0.53). OS is immature.This is different from camizestrant (#SERENA6), where the switch happens when ESR1 is detected on ctDNA, before progression. Why ESR1-only? Imlunestrant alone did not beat standard endocrine therapy outside ESR1m disease. What we still don't know: is imlunestrant plus abemaciclib better than abemaciclib plus fulvestrant? And does abemaciclib work after progression on first-line abemaciclib? Prior CDK4/6 inhibitor was not required in EMBER-3, and only 8% in postMONARCH had prior abemaciclib. #bcsm https://t.co/hsnHsRMPZV
FDA has approved imlunestrant in combo w/ abemaciclib for adults w/ ER+/HER2-/ESR1 mutated #metastaticbreastcancer after disease progression on at least 1 line of endocrine therapy. Based on EMBER-3 PFS results. ⚠️ OS results not yet mature #bcsm #OncTwitter #regulatory #MBC
The FDA approved the Imlunestrant (oral SERD) + Abemaciclib combo for ER+/HER2- MBC with an ESR1 mut with disease progression following at least 1 line of endocrine therapy based on results from EMBER-3 (COI). https://t.co/Gz2mFS0o0l https://t.co/pwHx4xdHCe @OncoAlert 1/3
After the initial **monotherapy-only approval from EMBER-3—which surprised me at the time—**the FDA has now approved imlunestrant + abemaciclib for ESR1-mutated, ER+/HER2− advanced breast cancer ✅ https://t.co/4KM60MXdQK
Imlunestrant + Abema now @FDA ✅ based off EMBER-3: Ph III, #Imlunestrant +/-#Abemaciclib in HR+ mESR1 advanced BC! - Imlunestrant alone for mESR1 approved. - Combo⬆️ mPFS w/all comers (11.1mos vs 5.5mos) - If co-PIK3CA, Capi or this combo? #bcsm #OncTwitter @OncUpdates https://t.co/Hs1JAT8uHG
Design — Phase 3, 1:1:1; imlunestrant mono (400 mg) vs investigator's-choice ET vs imlunestrant + abemaciclib, ER+/HER2- advanced BC after ET, n=874 (NCT04975308). (NEJM)
PFS (ESR1-mutant, primary) — Median 5.5 vs 3.8 months; HR 0.62 (95% CI 0.46-0.82; p=0.0008) — 38% reduction in progression/death. (NEJM 2024)
Overall survival — ESR1-mutant median OS 34.5 vs 23.1 months; HR 0.60 (95% CI 0.43-0.86; p=0.0043) — did not cross the prespecified boundary at that interim. (updated OS, med f/u 28.5 mo)
Safety — Favorable, endocrine-like; Grade 3/4 AEs 17% vs 21%; most common fatigue 23%, diarrhea 22%, nausea 17%, mostly Grade 1. (NEJM)
Regulatory — FDA approved September 25, 2025 for ESR1-mutated disease; Guardant360 CDx companion diagnostic. (FDA.gov)
Sponsor / Drug — Eli Lilly; imlunestrant (Inluriyo), an oral next-generation SERD. (FDA label)
Compiled and reviewed by the KOL Pulse research team, led by Brian Shields, Founder, KOL Pulse. Last updated September 19, 2026.
Top 10 by impressions - click to view on X
A lot was covered but summary of 7 main studies we touched on during Metastatic HR+ #BreastCancer #SABCS highlights w/ @hoperugo: ✅...
The new #Halgorithm for treating HR+/HER2- metastatic breast cancer @DrHBurstein @SABCSSanAntonio @DFCI_BreastOnc #bcsm...
Metastatic HR+ #BreastCancer #SABCS highlights w/ @hoperugo: ✅ #AMBRE ✅ #MONALEESA ✅ #VIKTORIA1 ✅...
#SABCS2025 Honored to present this exciting data. Efficacy seen regardless of mESR1 or mPIK3CA with ela+eve. Data immature for abema. EVERA also shows benefit with giredestrant/EVE...
#ESMOBreast25 is in 5 Days! One of the key upcoming presentations: EMBER-3 Subgroup Analysis 📌Imlunestrant + abema improved PFS after CDK4/6i (vs. Imlu) 📌No abema benefit after...
#SABCS24 Part 2: Highlights w/ @jamecancerdoc ✅ #EUROPA ✅ #TAILORx ✅ #PADMA ✅ #EMBER3 Full 📢: ...
key oral abstracts in breast cancer from #ASCO25 Covering neoadjuvant, adjuvant & metastatic settings: INAVO120, EMBER-3, VERITAC-2, DESTINY-Breast06, AXSANA, I-SPY2...
Ember 3 updated results. Imlu maintaining benefit. Combo benefit similar to evera trial although here benefit regardless of esr1m. Would love to see the combo approved to allow us more options for...
#SABCS24 beautiful discussion by @DrHBurstein on EMBER3. One of the best!! A fabulous and well qualified accumulation of data attached. Wow. @OncoAlert
📌 Educational Session 1: After CDK4/6 Inhibitors-Advancing Treatment for HR+HER2-negative Metastatic Breast Cancer ✨Treatment strategies after CDK4/6 inhibitor progression Mafalda Oliveira at...
EMBER-3 is a Phase III, randomized, open-label trial that evaluated imlunestrant (Inluriyo), a next-generation oral selective estrogen receptor degrader (SERD), in patients with ER-positive, HER2-negative advanced or metastatic breast cancer previously treated with endocrine therapy. The trial randomized 874 patients 1:1:1 to imlunestrant monotherapy (400 mg daily), investigator's choice of endocrine therapy (fulvestrant or exemestane), or imlunestrant plus abemaciclib. Imlunestrant demonstrated a statistically significant PFS improvement in the ESR1-mutant subgroup, leading to FDA approval in September 2025 as the second oral SERD for ESR1-mutated advanced breast cancer.
Phase III, global, open-label, 1:1:1 randomized trial in patients with ER+/HER2- locally advanced or metastatic breast cancer whose disease progressed on an aromatase inhibitor with or without a CDK4/6 inhibitor. ESR1 mutational status was determined by blood ctDNA analysis using the Guardant360 CDx assay. Randomization was stratified by prior CDK4/6 inhibitor use, presence of visceral metastases, and geographic region.
874 adult patients (men and pre/postmenopausal women) with ER+/HER2- advanced or metastatic breast cancer who progressed on prior aromatase inhibitor therapy with or without a CDK4/6 inhibitor. Approximately 37% had ESR1 mutations, 38% had PI3K pathway mutations, 60% had received prior CDK4/6 inhibitor therapy, 32% enrolled as first-line for metastatic disease, and 64% as second-line. Patients eligible for PARP inhibitors were excluded.
Imlunestrant 400 mg orally once daily versus investigator's choice of fulvestrant 500 mg IM or exemestane 25 mg daily. A third arm evaluated imlunestrant 400 mg daily plus abemaciclib 150 mg twice daily (added via protocol amendment).
Primary endpoints: investigator-assessed PFS of imlunestrant vs SOC in ESR1-mutant patients, imlunestrant vs SOC in all patients, and imlunestrant plus abemaciclib vs imlunestrant alone in all patients. Key secondary endpoint: overall survival (tested sequentially if PFS was significant). Other endpoints included ORR, time to chemotherapy, PFS2, and patient-reported outcomes.
In the ESR1-mutant population (n=256), imlunestrant demonstrated median PFS of 5.5 months (95% CI: 3.9-7.4) vs 3.8 months (95% CI: 3.7-5.5) for physician's choice, with HR 0.62 (95% CI: 0.46-0.82; p=0.0008), a 38% reduction in risk of progression or death. PFS in the ITT overall population was not statistically significant. The imlunestrant plus abemaciclib combination achieved median PFS of 10.9 months vs 5.5 months for imlunestrant alone (updated HR 0.59; 95% CI: 0.47-0.74; p<0.0001), with benefit regardless of ESR1 status.
Updated OS data (median follow-up 28.5 months) showed median OS of 34.5 months with imlunestrant vs 23.1 months with SOC in ESR1-mutant patients (HR 0.60; 95% CI: 0.43-0.86; p=0.0043), an 11.4-month improvement, although this did not meet the prespecified boundary for statistical significance. The combination showed a favorable OS trend (HR 0.82; 95% CI: 0.59-1.16). ORR was 14.3% for imlunestrant vs 7.7% for SOC in ESR1-mutant patients.
Imlunestrant monotherapy had a favorable safety profile consistent with endocrine therapy. Grade 3/4 AEs occurred in 17% (vs 21% for SOC). Most common AEs were fatigue (23%), diarrhea (22%), and nausea (17%), predominantly grade 1. Treatment discontinuation due to AEs was only 4%. No cardiac or ocular toxicity signals (no bradycardia or photopsia). The combination with abemaciclib showed expected CDK4/6i toxicity: diarrhea (86%/8% G3), nausea (49%/2% G3), neutropenia (48%/20% G3), with 6% discontinuation rate.
EMBER-3 established imlunestrant as a well-tolerated oral alternative to fulvestrant for ESR1-mutated ER+/HER2- advanced breast cancer, with the key advantage of oral administration eliminating injection-site reactions reported by 72% of fulvestrant patients. The monotherapy benefit is strictly biomarker-gated to ESR1-mutant tumors, mandating Guardant360 CDx liquid biopsy testing. The combination with abemaciclib extends benefit to all patients regardless of ESR1 status, supporting continued CDK4/6 inhibition beyond progression. Key debates include monotherapy vs. combination (QoL advantage of mono vs. PFS advantage of combo), competition with elacestrant and camizestrant in the oral SERD space, and the role of ESR1 testing infrastructure in clinical workflow.
EMBER-3 is a Phase 3, randomized, open-label trial (NCT04975308) of imlunestrant (Inluriyo), a next-generation oral SERD, in 874 patients with ER-positive/HER2-negative advanced breast cancer previously treated with endocrine therapy, randomized 1:1:1 to imlunestrant monotherapy, investigator's choice of endocrine therapy, or imlunestrant plus abemaciclib.
Yes. On September 25, 2025 the FDA approved imlunestrant (Inluriyo) for adults with ER-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer that progressed after at least one line of endocrine therapy. The Guardant360 CDx assay was approved as a companion diagnostic to detect ESR1 mutations in blood.
In the ESR1-mutant population (n=256), imlunestrant monotherapy improved median progression-free survival to 5.5 months versus 3.8 months for standard endocrine therapy (HR 0.62; 95% CI 0.46-0.82; p=0.0008), a 38% reduction in the risk of progression or death.
No. The FDA approval is specifically for ESR1-mutated disease, identified by the Guardant360 CDx companion diagnostic. The imlunestrant + abemaciclib combination arm remains under continued study and is not part of this monotherapy approval.
Imlunestrant (Inluriyo) is an oral, next-generation selective estrogen receptor degrader (SERD) developed by Eli Lilly, administered as 400 mg once daily.
