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Liquid Biopsy IDs More NSCLC Mutations, Yields Patient Therapy Response in Study of Guardant Test

NEW YORK (GenomeWeb) – New data this week has added evidence for the value of blood-based cancer testing in non-small cell lung cancer, demonstrating in a cohort of about 300 that comprehensive liquid biopsy — in this case Guardant Health's Guardant360 test — can help identify targeted mutations in more patients than tissue sequencing.

The study also found that patients treated on the basis of blood-based test results respond to treatment similarly to those treated based on tissue test results.

Testing patients' blood and tissue in parallel (and their blood alone in cases where a tissue sample was unavailable or impossible) investigators from the Abramson Cancer Center of the University of Pennsylvania reported that the use of liquid biopsy nearly doubled the number of mutations they detected compared to solid tissue alone.

In addition, 86 percent of patients with targetable mutations identified via liquid biopsy achieved either a complete response, partial response, or showed stable disease, authors reported in JAMA Oncology yesterday.

"Our goal here was to quantify the effect of using liquid biopsy in the real-world clinical setting," senior author Erica Carpenter, director of the Abramson Cancer Center's Circulating Tumor Material Center, said in a statement.

"We found patients whose therapies were selected based on the liquid biopsy results generally achieved a positive clinical response," she added.

In the study, Carpenter and colleagues tested 323 patients treated at Abramson between April 2016 and January 2018. Overall, 113 of these patients, about 35 percent, had some targeted mutation detected in either tissue or in their blood samples by the Guardant assay.

Across the 229 patients who had both liquid and solid biopsy results or for whom solid biopsy was not possible, the addition of liquid biopsy nearly doubled the number of mutations detected from 47 to 82.

Sixty-seven patients received a targeted therapy based on a mutation detected either by liquid biopsy alone or liquid and solid biopsy together. Of those, 42 were evaluated for their response, and 36 achieved either a complete response, partial response, or showed stable disease.

The group stressed that the data do not imply that liquid biopsy can replace tissue tests. 

"Solid tissue biopsy is still essential for accurate diagnosis, but we've now shown liquid biopsy can add value when it's used additionally, and also that it can serve as a viable alternative when solid biopsies aren't feasible … [and] given how rapidly targeted therapies are evolving, this is something that should be routinely incorporated into standard of care,' Carpenter added.

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