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  6. FDA approves imlunestrant in combination with abemaciclib for ER-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer
  1. Resources for Information | Approved Drugs

FDA approves imlunestrant in combination with abemaciclib for ER-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer

On September 18, 2026, the Food and Drug Administration approved imlunestrant (Inluriyo) in combination with abemaciclib (Verzenio), for adults with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, estrogen receptor 1 (ESR1)-mutated advanced or metastatic breast cancer, as detected by an FDA-authorized test, with disease progression following at least one line of endocrine therapy. Inluriyo and Verzenio are manufactured by Eli Lilly and Company.

FDA also approved the Guardant360 CDx assay as a companion diagnostic device to identify patients with breast cancer with ESR1 mutations for treatment with imlunestrant and abemaciclib.

Full prescribing information for Inluriyo and Verzenio will be posted on Drugs@FDA.

Efficacy and Safety

Efficacy was evaluated in EMBER-3 (NCT04975308), a randomized, open-label, active-controlled, multicenter trial that enrolled 874 adults with ER-positive, HER2-negative, locally advanced or metastatic breast cancer previously treated with an aromatase inhibitor either alone or in combination with a CDK4/6 inhibitor. Patients were excluded if they were eligible to receive a PARP inhibitor.

Patients were randomized 1:1:1 to imlunestrant, an investigator’s choice of endocrine therapy (fulvestrant or exemestane), or imlunestrant in combination with abemaciclib. Randomization was stratified by previous treatment with a CDK4/6 inhibitor, presence of visceral metastasis, and geographic region. ESR1 mutational status was determined by blood circulating tumor deoxyribonucleic acid (ctDNA) analysis using the Guardant360 CDx assay and was limited to specific ESR1 mutations in the ligand-binding domain.

The major efficacy outcome measure for the combination of imlunestrant with abemaciclib was investigator-assessed progression-free survival (PFS) according to RECIST v1.1 in the overall population, comparing imlunestrant plus abemaciclib to imlunestrant monotherapy. Other efficacy outcome measures included overall survival (OS) and investigator-assessed objective response rate (ORR). While the comparison of PFS between imlunestrant in combination with abemaciclib vs. imlunestrant monotherapy in the overall population was statistically significant, a PFS improvement was not demonstrated for imlunestrant monotherapy compared to investigator’s choice of endocrine therapy in either the overall or ESR1m-not-detected populations, indicating that the benefit was only observed in the ESR1m population. In an exploratory subgroup analysis in 159 patients with ESR1 mutated tumors for the combination, the PFS HR estimate was 0.53 (95% CI: 0.35, 0.80). Median PFS in patients with ESR1 mutated tumors was 11.1 months (95% CI: 7.4, 13.7) in the imlunestrant and abemaciclib arm and 5.5 months (95% CI: 3.8, 7.2) in the imlunestrant alone arm. ORR was 35% (95% CI: 22, 48) and 15% (95% CI: 7, 23) in the respective arms. At the time of interim analysis, OS data was immature with 35% of deaths in patients with ESR1 mutated tumors.

The imlunestrant prescribing information includes warnings and precautions for embryo-fetal toxicity. The abemaciclib prescribing information includes warnings and precautions for diarrhea, neutropenia, interstitial lung disease or pneumonitis, hepatotoxicity, venous thromboembolism, and embryo-fetal toxicity.

Recommended Dosage

The recommended dosage of imlunestrant is 400 mg orally once daily (on an empty stomach at least two hours before food or one hour after food) and the recommended dosage of abemaciclib in combination is 150 mg orally twice daily (with or without food) until disease progression or unacceptable toxicity.

This review used the Assessment Aid, a voluntary submission from the applicant to facilitate the FDA’s assessment.

Healthcare professionals should report all serious adverse events suspected to be associated with the use of any medicine and device to FDA’s MedWatch Reporting System or by calling 1-800-FDA-1088.

For assistance with single-patient INDs for investigational oncology products, healthcare professionals may contact OCE’s Project Facilitate at 240-402-0004 or email OncProjectFacilitate@fda.hhs.gov.

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