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Issue link: http://clinicalomics.epubxp.com/i/798822
www.clinicalomics.com March/April 2017 Clinical OMICs 27 The questions about the utility of liquid biopsy included whether enough relevant material was shed into the blood, and whether that amount was easy to detect and assay . Fur- thermore, tissue biopsy has long been the gold standard for testing, and is well understood . At the time the consensus was that "anybody who wants to do a liquid biopsy needs to prove it is at least going to be as good as what we are currently using," Brunel noted. Today, amid significantly improved collection and anal- ysis techniques, Helmy Eltoukhy, Ph . D . , CEO of Guardant Health, says the adoption of liquid biopsy has followed the same adoption curve as other disruptive technologies, and agrees with Brunel's assessment . "When you look at the revolution from wired to wireless technology, wireless only took off when it could provide the same experience and the same capabilities that its wired counterparts could," Dr. Eltoukhy said. "It is the same thing we see with liquid biopsies—that critical inflection point was getting to a level of performance tantamount to the tis- sue counterparts." Liquid Biopsy in Clinical Care While academic medical centers have been exploring the practical uses of liquid biopsy, and momentum has been building for a few years, work published last April in JAMA Oncology by Geoffrey Oxnard, M.D., and colleagues at Dana Farber Cancer Institute on the use of digital drop- let polymerase chain reaction (ddPCR) for liquid biopsy in non-small cell lung cancer (NSCLC), clearly moved the needle toward application of the technology in the broader medical community . The research, which compared results of liquid biopsy to standard tissue biopsy for the detection of EGFR and KRAS mutations, found the "predictive value" of plasma ddPCR was 100% for the primary EGFR mutation and the KRAS mutation . In other words, a patient who tested positive for either of these two mutations was certain to have that muta- tion in their tumor . For patients with the EGFR resistance mutation, the predictive value of the ddPCR test was 79%, meaning the liquid biopsy method found additional cases with the mutation that were missed using standard tissue biopsy . "There is the possibility that by checking [NSCLC patients] this way to see if they are EGFR mutant or whether they have a KRAS mutation, will give you insight to about half the patients that walk in the door within, potentially, a couple of days," said George Karlin-Neumann, Ph.D., director of scientific affairs at the Bio-Rad Digital Biology Center . "Speed can be important in getting patients treated weeks, or maybe a month or more earlier, by doing the liq- uid biopsy." Paul Walker, M . D . , chief of hematology/oncology at the Brody School of Medicine at East Carolina University had Yu-Hang Tang, Brown University / US Government Work (continued on next page) Red blood cells (red) and circulating tumor cells (green) traveling through a microfluidic cell-sorting device as simulated by UDEVICEX.