FDA Approves All-Oral Imlunestrant-Abemaciclib Breast Cancer Regimen

Eli Lilly and Company announced that the FDA has granted full approval to imlunestrant (Inluriyo, Lilly) in combination with abemaciclib (Verzenio, Lilly) for adults with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2–), ESR1-mutated locally advanced or metastatic breast cancer.

The indication applies when the ESR1 mutation is detected by an FDA-authorized test and disease has progressed after at least 1 line of endocrine therapy. The all-oral regimen combines imlunestrant, an estrogen receptor antagonist, with the CDK4/6 inhibitor abemaciclib.

Approval was supported by the phase 3 EMBER-3 trial, which included 159 patients with ESR1-mutated metastatic breast cancer. After prior treatment with an aromatase inhibitor, with or without a CDK4/6 inhibitor, patients received imlunestrant alone (n=92) or imlunestrant plus abemaciclib (n=67). Median progression-free survival was 11.1 months with the combination and 5.5 months with imlunestrant alone (hazard ratio, 0.53; 95% CI, 0.35-0.80).

Most adverse events with the combination were grade 1 or 2. Serious adverse reactions occurred in 21% of patients, and fatal adverse reactions occurred in 3.8%. The most common adverse reactions and laboratory abnormalities, reported in at least 10% of patients, included decreased neutrophils, diarrhea, decreased hemoglobin and lymphocytes, nausea, fatigue, infections, increased hepatic transaminases, and increased creatinine. Permanent discontinuation of imlunestrant alone because of adverse reactions occurred in 1% of patients; abemaciclib alone was discontinued in 3.4%.

The imlunestrant label includes a warning and precaution for embryo-fetal toxicity. The abemaciclib label includes warnings and precautions for severe diarrhea, neutropenia, interstitial lung disease or pneumonitis, hepatotoxicity, venous thromboembolism, embryo-fetal toxicity, and increased serum creatinine without impaired renal function. This is the second FDA approval for imlunestrant following its 2025 monotherapy approval in the same biomarker-defined disease setting.

Source: Eli Lilly and Company. U.S. FDA approves Inluriyo (imlunestrant) in combination with Verzenio (abemaciclib) for adults with ER+, HER2-, ESR1-mutated advanced or metastatic breast cancer. News release. Eli Lilly and Company; September 18, 2026. Accessed September 18, 2026.