A new pill called giredestrant may lower the risk of early-stage breast cancer coming back for people with hormone receptor (HR)-positive, HER2-negative breast cancer, the most common type of breast cancer. In a large international study presented at the San Antonio Breast Cancer Symposium, giredestrant worked better than standard hormone therapies such as tamoxifen or aromatase inhibitors when given after surgery.
What Type of Breast Cancer Was Studied?
The trial focused on early-stage (stage 1–3) HR-positive, HER2-negative breast cancer, which accounts for about 70% of all breast cancer diagnoses. Many people with this type of breast cancer have surgery followed by at least five years of hormone (endocrine) therapy to reduce the chance that cancer will return.
How Does Giredestrant Work?
Giredestrant is an oral selective estrogen receptor degrader (SERD), a newer class of hormone therapy medicines. It is designed to both block and break down the estrogen receptor, which helps shut down signals that can cause HR-positive breast cancer cells to grow and survive.
What Did the lidERA Clinical Trial Show?
In the phase III lidERA trial, 4,170 people with early-stage HR-positive, HER2-negative breast cancer were randomly assigned to receive either 30 mg of giredestrant or one of several standard hormone therapies for up to five years after surgery. After a median follow-up of about 32 months, patients taking giredestrant were about 30% less likely to have their cancer return or worsen (invasive disease-free survival), and there was also a 31% reduction in the risk of the cancer spreading to distant organs.
Side Effects and Safety
The most common side effects with giredestrant were similar to standard hormone therapies and included joint pain, hot flashes, and headaches, and most were mild. Fewer people stopped treatment because of side effects with giredestrant than with standard therapies, although mild, symptom-free slow heart rate (bradycardia) occurred more often with giredestrant and rarely needed treatment.
What This Could Mean for Patients
For more than 25 years, drugs like tamoxifen and aromatase inhibitors have been the main hormone treatments after surgery for HR-positive breast cancer. If longer follow-up confirms these results, giredestrant could become a new option that offers stronger protection against recurrence for many people with early-stage HR-positive, HER2-negative breast cancer.
Reference
Bardia A, et al. Giredestrant vs standard-of-care endocrine therapy as adjuvant treatment for patients with estrogen receptor-positive, HER2-negative early breast cancer: Results from the global Phase III lidERA Breast Cancer trial. Presented at: San Antonio Breast Cancer Symposium (SABCS); 2025 December 9-12; San Antonio, Texas, United States. #GS1-10.
