To identify patients with hormone receptor–positive, HER2-negative advanced or metastatic breast cancer with ESR1 mutations before radiographic disease progression, who may benefit from camizestrant.
Approach:
Testing Method: Guardant360 CDx is a liquid biopsy for comprehensive genomic profiling that detects multiple genomic alterations across solid tumors.
Study Design: The approval was based on data from the phase 3 SERENA-6 trial, where patients underwent testing every 3 months during therapy.
Treatment Protocol: Patients switched to camizestrant upon detection of an ESR1 mutation while continuing a cyclin-dependent kinase 4/6 inhibitor.
Key Findings:
Patients who switched to camizestrant had a 56% lower risk of disease progression or death compared with those who continued the aromatase inhibitor plus a cyclin-dependent kinase 4/6 inhibitor.
There was a 47% reduction in the risk of deterioration in global health status and quality of life among patients treated under the circulating tumor DNA–guided approach.
Interpretation:
Biomarker testing in advanced cancer has typically occurred after clinical or radiographic progression, but this approach allows for earlier intervention.
Conclusion:
The approval represents the test’s 29th companion diagnostic indication across multiple tumor types globally.
