Giredestrant-Everolimus Doubles Survival in ESR1-Mutated Breast Cancer
The evERA trial shows the all-oral combination of giredestrant and everolimus significantly improves progression-free survival for patients with advanced breast cancer.
A new all-oral drug combination has shown significant benefit for people with advanced ER-positive, HER2-negative breast cancer whose disease progressed after standard therapy. The evERA trial results reveal giredestrant plus everolimus doubled median progression-free survival in patients with ESR1-mutated tumors, offering a promising new option where few exist.
The international phase III evERA trial enrolled 373 patients from 13 countries. Participants had locally advanced or metastatic ER-positive, HER2-negative breast cancer that progressed after treatment with a CDK4/6 inhibitor and endocrine therapy. The study included women of any menopausal status and men. Investigators randomized patients to receive either the giredestrant-everolimus combination or the investigator's choice of endocrine therapy plus everolimus. Pre- or perimenopausal women and men also received a luteinizing hormone-releasing hormone agonist. The primary goal was to measure investigator-assessed progression-free survival, first in the ESR1-mutated subgroup, which made up 55% of participants, and then in the overall population.
Efficacy in ESR1-mutated and overall populations
Giredestrant plus everolimus significantly improved progression-free survival, doubling median PFS in ESR1-mutated patients and showing a 44% risk reduction in the intent-to-treat population.
In patients with ESR1-mutated cancers, the combination reduced the risk of disease progression or death by 62% compared to standard endocrine therapy plus everolimus. Median progression-free survival jumped from 5.5 months to 10.0 months. The stratified hazard ratio was 0.38.
For the entire study population, the risk of progression or death was reduced by 44%. Median PFS increased from 5.5 months to 8.8 months with the experimental regimen. The benefit was consistent across most patient subgroups, including those with specific genetic alterations and regardless of how long they had received prior CDK4/6 inhibitor therapy.
| Population | Median PFS (Giredestrant + Everolimus) | Median PFS (Control) | Hazard Ratio (95% CI) |
|---|---|---|---|
| ESR1-Mutated | 10.0 months | 5.5 months | 0.38 (0.27-0.54) |
| Overall (ITT) | 8.8 months | 5.5 months | 0.56 (0.44-0.71) |
Survival trends and safety profile
While overall survival data remain immature, a positive trend was observed, and the safety profile of giredestrant plus everolimus was manageable and consistent with known profiles of the individual agents.
Initial overall survival data show a promising trend. In the overall population, the hazard ratio was 0.69. For the ESR1-mutated group, it was 0.62. The 18-month overall survival estimate for ESR1-mutated patients was 71.5% with giredestrant-everolimus versus 50.9% in the control arm.
The safety profile was similar between the two treatment groups, with no unexpected findings. Adverse events were common but manageable. The most frequent side effects in both arms were stomatitis, diarrhea, and anemia. Fatal adverse events occurred in 2.7% of patients in each group.
| Adverse Event | Giredestrant + Everolimus | Control Arm |
|---|---|---|
| Stomatitis | 47.3% | 48.9% |
| Diarrhea | 26.9% | 22.6% |
| Anemia | 23.6% | 21.0% |
Clinical significance and regulatory status
The all-oral regimen offers a meaningful delay in chemotherapy use and builds on prior oral SERD successes, with FDA acceptance of the NDA and a PDUFA date set for December 2026.
This trial addresses a critical gap. After first-line CDK4/6 inhibitor therapy fails, options are limited. Resistance often involves ESR1 mutations or changes in the PI3K/AKT/mTOR pathway. The new combination targets two distinct signaling pathways. "The giredestrant-everolimus combination has the advantage of targeting two distinct signaling pathways, providing improved efficacy," said Erica J. Mayer of Dana-Farber Cancer Institute.
The all-oral nature could reduce treatment burden by eliminating injections. The results may support sequencing strategies that delay chemotherapy. "Patients in the clinical trial achieved a median progression-free survival of 10 months, which is clinically meaningful in this treatment setting," noted Aditya Bardia of UCLA Health.
The U.S. Food and Drug Administration has accepted a New Drug Application for giredestrant plus everolimus under Priority Review. A separate NDA for giredestrant as an adjuvant treatment was also accepted. The agency is expected to decide on the metastatic breast cancer application by December 18, 2026.
