The U.S. Food and Drug Administration (FDA) recently approved the cobas EGFR Mutation Test v2, a blood-based companion diagnostic for the epidermal growth factor receptor (EGFR) inhibitor erlotinib (Tarceva). This is the first FDA-approved, blood-based genetic test that can detect EGFR gene mutations in non–small cell lung cancer (NSCLC) patients. Such mutations are present in approximately 10% to 20% of NSCLC.
NSCLC tumors may shed tumor DNA into a patient’s blood, making it possible to detect specific mutations in blood samples. Testing for tumor DNA using a blood sample is also called a liquid biopsy.
“Approvals of liquid biopsy tests make it possible to deliver highly individualized health care for patients,” said Alberto Gutierrez, PhD, Director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health. “Liquid biopsies also have the potential to allow physicians to identify patients whose tumors have specific mutations in the least invasive way possible.”
Cobas EGFR Mutation Test v2
With the cobas EGFR Mutation Test v2, the presence of specific NSCLC mutations [exon 19 deletion or exon 21 (L858R) substitution mutations] detected in patients’ blood samples aids in selecting those who may benefit from treatment with erlotinib. However, if such mutations are not detected in the blood, then a tumor biopsy should be performed to determine if the NSCLC mutations are present. Insofar as the test provides positive results, it may benefit patients who may be too ill or are otherwise unable to provide a tumor specimen for EGFR testing.
The efficacy of the cobas EGFR Mutation Test v2 using blood samples was determined by using the test to identify the EGFR mutation status in patients enrolled into a clinical trial whose tumor biopsies were previously confirmed positive for the EGFR exon 19 deletion or L858R mutations as determined by the cobas EGFR Mutation Test v1. ■