24 April 2017
ByAppeared in BioNews 897
The genetic test, published in The Journal of Molecular Diagnostics, could identify specific 'actionable' mutations with diagnostic or therapeutic implications for non-small cell lung cancer (NSCLC), which accounts for 80-85 percent of lung cancer incidences.
'This study is critical because it is the first to demonstrate the uptake of blood-based testing for actionable mutations in the non-hospital (community) setting. Physicians and patients in a community setting may not have easy access to a large hospital or other diagnosis/treatment facility,' said Dr Gary Pestano, lead author of the study and vice-president of Biodesix, Colorado, the molecular diagnostic company behind the test.
The test exploits the presence of nucleic acid fragments in the bloodstream that are shed by tumour cells. The researchers employed a technique called Digital Droplet polymerase chain reaction (PCR) which partitions the blood sample into thousands of 'droplets' containing DNA or RNA, each acting as an isolated reaction tube. This enables detection of tumour-derived nucleic acids even though they are far outnumbered by normal cellular material.
The researchers tested 1643 samples from patients who had been diagnosed with NSCLC, and were able to detect mutations with sensitivity and specificity comparable to tissue biopsies. The study reported a turnaround time of 72 hours from receipt of a blood sample in 94 percent of the cases, superseding conventional lung tissue or fluid biopsies which can take weeks.
Although the test only detects seven different types of mutations, the authors believe this information will be valuable in a clinician's decision-making process. Approximately one-fourth of patients with NSCLC either cannot undergo biopsy or have insufficient tissue samples recovered from the initial biopsy, meaning the cancer genotype cannot be diagnosed.
This study highlights growing commercial interest in so-called 'liquid biopsy'-based cancer tests, and comes in the wake of several commercially available tests recently launched.