The US Food and Drug Administration (FDA) has approved the first blood-based genetic test, known as a “liquid biopsy,” that can detect EGFR gene mutations in non-small cell lung cancer (NSCLC) in plasma. Designed to be used as a companion diagnostic for erlotinib, the cobas EGFR Mutation Test v2 detects specific NSCLC mutations, such as the exon 19 deletion or exon 21 (L858R) substitutions.1

“The tissue biopsy is still considered the gold standard, though tissue is precious and there’s often times where there is not enough tissue left over to do molecular testing. In those common scenarios, plasma can be used to help do the genotyping,” Benjamin Levy, MD, medical director of Thoracic Medical Oncology for Mount Sinai Health Systems, and associate medical director of the Cancer Clinical Trials Office for Mount Sinai Hospital in New York, New York, told Cancer Therapy Advisor.

“You should still get a tissue biopsy for patients with suspected lung cancer, but this may avert the need for rebiopsies,” added Dr Levy.

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“In my practice, we are ordering blood on most of our patients, because the blood turnaround time is so quick, and the genotyping that’s done on the tissue in institutions takes up to 21 days. It’s better to get a quick answer with a minimally invasive test. I don’t see tissue and plasma as mutually exclusive.” The test’s specificity is quite high: if positive, it rules in EGFR mutations. “If it’s negative, then you still need to do the biopsy,” he said.

John McNamara, senior international product manager, genomics & oncology at Roche Molecular Systems, the test’s manufacturer, told Cancer Therapy Advisor that test results are available within 4 hours. At the time of the FDA approval, 4 US laboratories trained to perform the test were “up and running.”

The test’s efficacy was determined by identifying EGFR mutation status in patients enrolled in a clinical trial whose tumor biopsies were previously confirmed positive for EGFR mutations, “as determined by the cobas EGFR Mutation Test v1,” which uses tissue, the FDA stated in a press release.1

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“This is going to have far-reaching effects,” Dr Levy said. Although only 15% to 20% of patients with NSCLC have EGFR mutations, “we’re testing everybody. For patients with advanced disease, this should be on everybody’s radar, period.”

One of the largest cancer genomics studies ever conducted analyzed blood samples from more than 15,000 patients and 50 different tumor types. In results presented at the 2016 American Society of Clinical Oncology Annual Meeting, data confirmed the concordance of genetic changes in circulating tumor DNA with traditional tumor biopsies.2


  1. FDA approves first blood test to detect gene mutation associated with non-small cell lung cancer [news release]. Silver Spring, MD: U.S. Food and Drug Administration; June 1, 2016. Accessed June 1, 2016.
  2. Zill OA, Mortimer S, Banks KC, Nagy RJ, Chudova D, Jackson C, et al. Somatic genomic landscape of over 15,000 patients with advanced-stage cancer from clinical next-generation sequencing analysis of circulating tumor DNA. Paper presented at: 2016 Annual Meeting of the American Society of Clinical Oncology; June 2016; Chicago, IL.