Original from: Guardant Health
Guardant Health, Inc. (Nasdaq: GH), a leading precision oncology company, today announced that the U.S. Food and Drug Administration (FDA) has approved Guardant360® CDx as a companion diagnostic (CDx) to identify patients with hormone receptor (HR)-positive, HER2-negative advanced or metastatic breast cancer harboring tumors with ESR1 mutations before radiographic progression who may benefit from treatment with ETCAMAH™ (camizestrant), AstraZeneca’s next-generation oral selective estrogen receptor degrader (SERD). Guardant360 CDx is the first FDA-approved liquid biopsy CDx for longitudinal testing in breast cancer, and this approval represents a major shift from therapy selection and switching post-radiographic progression to adaptive cancer management and early interception using pre-radiographic progression circulating tumor DNA (ctDNA) testing.
The approval is based on data from the pivotal SERENA-6 clinical trial, which introduced a first-of-its-kind treatment strategy using ctDNA monitoring to detect emerging ESR1 resistance mutations before radiographic disease progression. Patients who switched to ETCAMAH in combination with continuing a cyclin-dependent kinase (CDK) 4/6 inhibitor versus continuing treatment with an aromatase inhibitor with a CDK4/6 inhibitor following ESR1 mutation detection experienced a 56% reduction in the risk of progression or death. The trial demonstrated the clinical value of proactively identifying disease progression earlier than radiographic imaging and adapting therapy earlier in the course of disease.
“This approval represents a landmark shift in how we define disease progression and reinforces the transformative role of liquid biopsy in guiding therapy decisions earlier at a critical moment in a breast cancer patient’s treatment journey,” said Helmy Eltoukhy, Guardant Health chairman and co-CEO. “The SERENA-6 paradigm opens a new frontier in how cancer is managed, with potential application across different diseases and therapies.”
Approximately 37,000 women in the U.S. living with advanced HR-positive breast cancer being treated with an aromatase inhibitor could potentially benefit from this new therapeutic approach leading to better progression-free survival and outcomes.
Advancing a New Precision Medicine Paradigm
Historically, biomarker testing in advanced cancer most often occurred after clinical or radiographic progression. The SERENA-6 study demonstrated the value in a fundamentally different approach: ctDNA surveillance during first-line endocrine therapy to identify the emergence of resistance before overt disease progression.
Patients enrolled in the study underwent serial testing with Guardant360 CDx every three months while receiving an aromatase inhibitor with a CDK4/6 inhibitor. Upon detection of an ESR1 mutation before radiographic progression, eligible patients were transitioned to camizestrant-based treatment. Patients treated under this new paradigm experienced 74% longer median progression-free survival (16.0 vs. 9.2 months) with a 47% reduction in risk of deterioration in global health status and quality of life.
Strategic Collaboration with AstraZeneca
The approval reflects a multi-year collaboration between Guardant Health and AstraZeneca focused on integrating Guardant Health products and capabilities into clinical development.
Guardant Health supported the study through its FDA-approved Guardant360 CDx platform, providing high-sensitivity ESR1 mutation detection capabilities across serial testing timepoints. The collaboration enabled accessible, scalable biomarker testing designed to support rapid clinical decision-making and broad patient access.
This latest FDA approval for Guardant360 CDx marks the 29th CDx indication across multiple tumor types globally, building on the platform’s increasing clinical utility and broad coverage by Medicare and commercial payers, representing more than 300 million covered lives.
Source: Guardant Health Announces Landmark FDA Approval of Guardant360® CDx as Companion Diagnostic for AstraZeneca’s ETCAMAH™ (camizestrant) in Advanced Breast Cancer
