Liquid biopsy offers the promise of more accurate, and potentially earlier, cancer diagnoses based on the genetic analysis of circulating tumor cells in the blood. While a lot of money and strategic interest is already chasing the notion of the liquid biopsy, now the FDA has signed off on the idea for the first time with an approval for a companion diagnostic for the oncology drug Tarceva.
This is the first liquid biopsy test that the agency has approved for use in clinical decision making. Known as the cobas EGFR Mutation Test v2, it's a blood-based genetic test to detect epidermal growth factor receptor (EGFR) gene mutations in non-small cell lung cancer patients (NSCLC).
EGFR testing via biopsy is currently being conducted on only about 25% of NSCLC patients, according to Roche ($RHHBY). The procedure can be too invasive for very sick patients and tumor tissue can be difficult to biopsy effectively.
"Approvals of liquid biopsy tests make it possible to deliver highly individualized health care for patients," said Alberto Gutierrez, director of the Office of In Vitro Diagnostics and Radiological Health in the FDA's Center for Devices and Radiological Health, in a statement. "Liquid biopsies also have the potential to allow physicians to identify patients whose tumors have specific mutations in the least invasive way possible."
The test is used on NSCLC patients to identify the presence of 42 EGFR mutations in exons 18-21. These indicate that a patient may benefit from treatment with Tarceva. But if the mutations are not found in the blood, a tumor biopsy would also be performed to search for them. But for patients who obtain a positive result with the test, it would allow them to avoid lung biopsy.
About 221,000 Americans are diagnosed annually with lung cancer, with NSCLC being the most common type. These specific mutations appear in roughly 10% to 20% of NSCLC cases.
"The FDA approval of the cobas EGFR Mutation Test v2 for liquid biopsy for diagnostic use sets a standard in testing for NSCLC patients," said Uwe Oberlaender, Head of Roche Molecular Diagnostics. "The approval of the test for use with plasma samples means patients who previously could not be tested now have a testing option for personalized healthcare."
The clinical testing of efficacy for cobas EGFR Mutation Test v2 was confirmed via tumor biopsy. Tarceva has been FDA-approved since 2004 to treat locally advanced or metastatic NSCLC after the failure of at least one prior chemotherapy regimen. In 2013, the agency approved it specifically for first-line treatment of patients with metastatic NSCLC whose tumors having EGFR exon 19 deletions or L858R substitution mutations.
Roche subsidiary Genentech and Astellas Pharma are partnered to develop and distribute Tarceva in the U.S., with Chugai marketing it in Japan and Roche in the rest of the world.
"The advent of liquid diagnostic platforms in non-small cell lung cancer is truly a game changer in the diagnostic workup of advanced stage patients. The ability to both isolate and genetically interrogate tumor DNA from a simple, minimally invasive test that can subsequently inform treatment decisions is a win for both physician and patient," said Dr. Benjamin Levy, director of Thoracic Medical Oncology at Mount Sinai Health Systems and Hospital. "These platforms have the potential to expedite care and potentially circumvent an otherwise cumbersome process of procuring tissue (biopsy) often fraught with complications and complexity."
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