FDA Approves Inluriyo With Verzenio for ESR1-Mutated Breast Cancer

Quick answer: On 18 September 2026, the US FDA approved Inluriyo (imlunestrant) in combination with Verzenio (abemaciclib), both from Eli Lilly. The approval is for adults with ER-positive, HER2-negative advanced or metastatic breast cancer that carries an ESR1 mutation and has progressed after at least one line of hormone (endocrine) therapy. In patients with ESR1 mutations, the combination roughly doubled median progression-free survival compared with Inluriyo alone (11.1 vs 5.5 months).

Why the ESR1 Mutation Matters

Hormone-positive breast cancer can stop responding to hormone therapy over time. One way this happens is through a change (mutation) in the ESR1 gene, which carries the instructions for the oestrogen receptor. This approval applies only when an FDA-authorised test finds an ESR1 mutation. Alongside the drug, the FDA approved the Guardant360 CDx blood test as the companion diagnostic, so a blood sample (not a new biopsy) can be used to check.

What the EMBER-3 Trial Found

EMBER-3 enrolled 874 adults whose cancer had already been treated with an aromatase inhibitor, alone or with a CDK4/6 inhibitor. They were split into three groups: Inluriyo alone, standard hormone therapy (fulvestrant or exemestane), or Inluriyo plus abemaciclib.

Results in the 159 patients with ESR1-mutated tumours

• Median progression-free survival: 11.1 months with the combination vs 5.5 months with Inluriyo alone
• Hazard ratio: 0.53
• Tumour response rate: 35% vs 15%

An honest caveat

The FDA points out that the benefit was seen only in the ESR1-mutated group, and that the ESR1 figures come from an exploratory subgroup analysis. Overall survival data were still immature at the time of the interim analysis.

Dosing and Safety

• Inluriyo: 400 mg by mouth once a day on an empty stomach (at least two hours before or one hour after food).
• Abemaciclib: 150 mg by mouth twice a day, with or without food.
• Inluriyo's label warns about harm to an unborn baby.
• Abemaciclib's label warns about diarrhoea, low white cell counts (neutropenia), lung inflammation, liver problems, blood clots and harm to an unborn baby.

Access Through NPP

If you're new to hormone-positive breast cancer, our HR-positive, HER2-negative breast cancer guide covers the basics. Doctors can find product details on the Inluriyo page and get in touch to start a named-patient request.

This news update is for information only and is not medical advice. Please discuss treatment options with your oncologist.

References

1. US FDA: FDA approves imlunestrant in combination with abemaciclib for ER-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer (18 Sep 2026)
2. ClinicalTrials.gov: EMBER-3, imlunestrant with or without abemaciclib in ER+, HER2- advanced breast cancer (NCT04975308)