FDA Approves New Oral Drug Inluriyo (imlunestrant) for Advanced ER-positive, HER2-negative, ESR1-mutated Breast Cancer

A new oral treatment called imlunestrant (Inluriyo) has been approved for people with ER-positive, HER2-negative metastatic breast cancer whose tumors carry an ESR1 mutation and have stopped responding to standard hormone therapy, offering longer control of the disease and a targeted option guided by a simple blood test.

Charles H. Weaver, MD
1–2 minutes
Home » Breast Cancer » FDA Approves New Oral Drug Inluriyo (imlunestrant) for Advanced ER-positive, HER2-negative, ESR1-mutated Breast Cancer

The U.S. Food and Drug Administration (FDA) has approved a new treatment option, imlunestrant (Inluriyo), for adults with advanced or metastatic breast cancer that is:

  • Estrogen receptor-positive (ER+)
  • HER2-negative
  • Has an ESR1 gene mutation
  • Has progressed despite at least one prior hormonal therapy

Clinical Study Results

  • In a major clinical trial with over 800 patients (EMBER-3), people with the ESR1 mutation who took imlunestrant lived longer without their cancer worsening. The median time before cancer growth (progression-free survival) was 5.5 months with imlunestrant versus 3.8 months with standard hormone options.
  • The overall response rate (how many tumors shrank) was higher with imlunestrant (14.3% vs. 7.7%).
  • Common side effects included low blood counts, muscle or joint aches, low calcium, fatigue, increased liver enzymes, diarrhea, and nausea. Most side effects were mild to moderate in severity.

Why This Matters

  • ESR1 gene mutations are a common cause of resistance to hormone therapy in metastatic breast cancer. Imlunestrant targets this mutation specifically, providing a much-needed option for those whose cancer has become resistant to other hormone treatments.
  • The medication is taken by mouth (oral) rather than by injection, making it more convenient for many patients.

About Imlunestrant

Imlunestrant is an oral estrogen receptor antagonist, meaning it blocks the effects of estrogen on cancer cells, which is important for cancers that use estrogen to grow. This drug is taken by mouth and offers a new choice for patients, especially those whose cancer has developed resistance to common hormone therapies.

Companion Testing

The FDA also approved the Guardant360 CDx blood test to identify patients whose tumors have the ESR1 gene mutation, so patients and doctors know who might benefit from imlunestrant.

Talk to your doctor to see if your cancer has an ESR1 mutation and whether Inluriyo could be an option for you. The new Guardant360 CDx blood test can help guide this decision by detecting these changes in your cancer.

Reference

https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-imlunestrant-er-positive-her2-negative-esr1-mutated-advanced-or-metastatic-breast

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