The U.S. Food and Drug Administration (FDA) recently approved a blood test as a companion diagnostic tool to detect genetic changes, or mutations, present in a common form of lung cancer. The test is to be used to determine if specific mutations exist in people with non-small cell lung cancer (NSCLC), who would be eligible for first-line treatment with the drug Tarceva (erlotinib).
Tumor biopsies, until now, were the only way to determine if a person carried specific mutations. However, some advanced-stage patients may be too ill to undergo a biopsy. The minimally invasive test, called cobas EGFR Mutation Test v2 and developed by Roche, makes it possible to test for mutations from blood samples. (If the mutation is not detected from the blood, a biopsy may still be needed.)
DNA from tumors can leak into the blood stream, making it possible to detect specific mutations using blood samples. Such testing, for this reason, is also called a “liquid biopsy.”
“Approvals of liquid biopsy tests make it possible to deliver highly individualized health care for patients,” Dr. Alberto Gutierrez, director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health, said in a press release. “Liquid biopsies also have the potential to allow physicians to identify patients whose tumors have specific mutations in the least invasive way possible.”
Roughly 10 percent to 20 percent of all non-small cell lung cancers show a mutation in the epidermal growth factor receptor (EGFR) gene. The cobas test is able to detect 42 different mutations in the EGFR gene associated with NSCLC.
Erlotinib is approved to treat patients with locally advanced or metastatic NSCLC after failure of at least one prior chemotherapy regimen. The drug is also indicated as a first-line treatment for patients with metastatic NSCLC whose tumors have certain mutations (exon 19 deletions or exon 21 [L858R] substitution mutations) in the EGFR gene.