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SERENA-6 Phase III Trial Demonstrates Clinical Value of Guardant360 CDx Test to Detect Emergence of Endocrine Resistance and Inform a Switch in Therapy Before Radiological Disease Progression in Advanced Breast Cancer
First pivotal trial to use a circulating tumor DNA (ctDNA)-guided approach to detect and treat emerging resistance in 1st-line therapy ahead of disease
About this update from Guardant Health, Inc.
[{"type":"text","content":"\n\nFirst pivotal trial to use a circulating tumor DNA (ctDNA)-guided approach to detect and treat emerging resistance in 1st-line therapy ahead of disease progression in breast cancer\n\n\n\n\nTrial showed AstraZeneca’s camizestrant reduced risk of disease progression or death by 56% in patients with advanced HR-positive breast cancer with an emergent ESR1 tumor mutation as detected by Guardant360 CDx\n\n\n\n PALO ALTO, Calif.--(BUSINESS WIRE)--\nGuardant Health, Inc. (Nasdaq: GH), a leading precision oncology company, today announced that the results of the Phase III SERENA-6 trial - sponsored by AstraZeneca - demonstrate the clinical value of the Guardant360® CDx test in a circulating tumor DNA-guided approach to detect and treat emerging resistance in 1st-line therapy ahead of radiological disease progression in breast cancer. Study results were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago and were published in The New England Journal of Medicine.\n\n\nSERENA-6 is the first global, double-blind, registrational Phase III trial to use a ctDNA-guided approach to detect the emergence of endocrine resistance and inform a switch in therapy before disease progression is detected in imaging scans. The novel trial design used ctDNA monitoring with the Guardant360 liquid biopsy test at the time of routine tumor scans to identify patients for early signs of endocrine resistance and the emergence of ESR1 mutations.\n\n\n“SERENA-6 is a landmark study that is creating a new paradigm using liquid biopsy to enable a switch to a new treatment as soon as you see the cancer showing signs of resistance,” said Helmy Eltoukhy, Guardant Health chairman and co-CEO. “This use of the Guardant360 CDx test highlights how we are pushing the boundaries of what can be done with liquid biopsy in characterizing disease and potential drug efficacy, providing insights that could potentially change clinical practice and improve outcomes in patients with advanced breast cancer.”\n\n\nFollowing detection of an ESR1 mutation without radiological disease progression, the endocrine therapy of patients was switched to AstraZeneca’s camizestrant from ongoing treatment with an aromatase inhibitor (AI), while continuing combination with the same cyclin-dependent kinase (CDK) 4/6 inhibitor. The trial demonstrated a highly ...