Clinical Report: ESMO Breast Cancer 2026 Highlights: SERENA-6

Overview

The SERENA-6 trial demonstrated that switching to camizestrant upon detection of ESR1 mutations improved progression-free survival (PFS) in patients with HR-positive/HER2-negative advanced breast cancer. The trial results were presented at the 2026 ESMO Breast Cancer Congress.

Background

The management of HR-positive/HER2-negative metastatic breast cancer is evolving, particularly with the emergence of ESR1 mutations during treatment. Current guidelines emphasize the importance of biomarker testing to inform treatment decisions, especially in the context of endocrine therapy combined with CDK4/6 inhibitors. The SERENA-6 trial provides data regarding the efficacy of camizestrant in this patient population.

Data Highlights

Key Findings

• Switching to camizestrant upon ESR1 mutation detection improved investigator-assessed PFS (HR 0.45).
• The median PFS was 16.8 months for the camizestrant group compared to 9.2 months for the aromatase inhibitor group.
• Statistically significant PFS2 benefit was observed with camizestrant.
• Patients in the trial were receiving first-line aromatase inhibitor plus CDK4/6 inhibitor without radiographic progression.
• ESR1 mutations were detected through ctDNA surveillance.

Clinical Implications

The SERENA-6 trial provides data that monitoring for ESR1 mutations can inform treatment decisions in HR-positive/HER2-negative advanced breast cancer.

Conclusion

The SERENA-6 trial provides data on camizestrant in patients with ESR1-mutated advanced breast cancer.

Related Resources & Content

1. Harold Burstein, MD, PhD, and Erica Mayer, MD, MPH, ESMO Breast Cancer 2026 Highlights: SERENA-6
2. Testing for ESR1 Mutations to Guide Therapy for Hormone Receptor–Positive, Human Epidermal Growth Factor Receptor 2–Negative Metastatic Breast Cancer: ASCO Guideline Rapid Recommendation Update | Journal of Clinical Oncology
3. Camizestrant Extends PFS and PFS2 in ESR1-Mutated Advanced Breast Cancer | CancerNetwork
4. dana-farber — ESMO Breast Cancer 2026 Highlights: Saci-IO HR+
5. dana-farber — ESMO Breast Cancer 2026 Highlights: TRAK-ER
6. The ASCO Post — SABCS 2025: High-Level Review of Select Data
7. The ASCO Post — SABCS 2025: High-Level Review of Select Data
8. Testing for ESR1 Mutations to Guide Therapy for Hormone Receptor–Positive, Human Epidermal Growth Factor Receptor 2–Negative Metastatic Breast Cancer: ASCO Guideline Rapid Recommendation Update | Journal of Clinical Oncology
9. Camizestrant Extends PFS and PFS2 in ESR1-Mutated Advanced Breast Cancer | CancerNetwork
10. SERENA-6 interpretation and clinical implications: intercepting endocrine resistance in metastatic breast cancer | npj Breast Cancer