The US FDA has recently approved Guardant360 CDx assay to identify metastatic non-small cell lung cancer (NSCLC) patients who carry specific epidermal growth factor receptor (EGFR) gene mutations, making them eligible for treatment with osimertinib (Tagrisso).
The diagnostic assay involves a combination of liquid biopsy and next-generation sequencing (NGS) technology. The liquid biopsy technology uses a blood sample to provide health care professionals with genetic information about the patient’s tumour. It is less invasive and more easily repeatable in comparison to standard tissue biopsies. Furthermore, liquid biopsy tests can be used in cases in which standard tissue biopsies are not feasible, for instance, due to the location of the tumour.
The second technology involved in the diagnostic assay is the NGS, which uses large-panel genetic sequencing, known as high-throughput tumour profiling. NGS requires only one test in order to allow clinicians to have a better assessment of tumour composition, allowing them to evaluate which mutations are problematic.
The NGS technology helps simultaneously detect mutations in 55 tumour genes at a time, according to the company. It thereby helps overcome challenges of tissue testing in advanced NSCLC by helping make first-line treatment decisions.
While the assay can provide information on multiple solid tumour biomarkers, it is specific to its use in identifying EGFR mutations in patients who will benefit from treatment with osimertinib which is an FDA-approved therapy for a form of metastatic NSCLC.
Genomic findings for other biomarkers evaluated are not validated for choosing a particular corresponding treatment with the current approval. If the specific NSCLC mutations associated with the approval are not detected in the blood, then a standard tumour biopsy should be performed to determine if the NSCLC mutations are present, noted the FDA
“Approval of a companion diagnostic that uses a liquid biopsy and leverages next-generation sequencing marks a new era for mutation testing,” said Tim Stenzel, MD, Ph D, director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health.
“In addition to benefitting from less invasive testing, patients are provided with a simultaneous mapping of multiple biomarkers of genomic alterations, rather than one biomarker at a time, which can translate to decreased wait times for starting treatment and provide insight into possible resistance mechanisms,” he added.