Liquid vs Tissue Biopsy in Detecting Biomarkers for Advanced NSCLC

A liquid biopsy test called Guardant360^® appears to be comparable to standard tissue biopsies in detecting guideline-recommended biomarkers in advanced non–small-cell lung cancer (NSCLC), according to the results of a new study that will be presented at the 2019 American Association for Cancer Research Meeting in Atlanta later this month. It also has a faster turnaround time and may identify more patients who can be treated with targeted therapy, according to researchers.

The study, conducted at several institutions, included a total of 282 patients who were evaluated with Guardant360. The test detected 7 known predictive biomarkers, including genomic alterations in ROS1, BRAF, RET, MET, ALK, EGFR, and ERBB2, as well as 1 prognostic biomarker (KRAS mutations).

Standard tissue sampling identified at least 1 predictive biomarker in 60 patients, and Guardant360 identified biomarkers in 77 patients. In the remaining 193 patients who did not have one of the 7 biomarkers, the liquid biopsy test found a KRAS mutation in 92 patients vs 24 patients with standard tissue sampling.

In addition, the study reported a median turnaround time, from test order to final results, of 9 days for the liquid biopsy test vs 15 days for tissue-based testing.

The researchers reported that 30% of lung cancers can be treated successfully with molecular-targeted therapies, which often yield higher response rates than chemotherapy. The US Food and Drug Administration has already approved treatments specifically targeting EGFR, ALK, ROS1, and BRAF gene mutations or fusions.

Lead study investigator Vassiliki Papadimitrakopoulou, MD, a professor of Thoracic Head and Neck Medical Oncology at the University of Texas MD Anderson Cancer Center in Houston, said that tissue biopsy–based mutation testing has been considered the standard for metastatic NSCLC patients. This is because prospective studies had not previously compared the ability of liquid biopsy vs tissue biopsy to completely and rapidly assess targetable mutations, he said.

“The NILE study was designed to address this question, and the main finding is that the detection rate of targetable mutations using Guardant360 liquid biopsy is similar to the detection rate of standard of care testing of tumor tissue. This finding should give confidence to oncologists to trust liquid biopsy as a testing option for treatment selection in NSCLC patients,” Papadimitrakopoulou told Cancer Network.

One of the study’s limitations is that the test was compared to the standard-of-care tissue genotyping test and not the tissue-based next-generation sequencing test. It also incorporated an analysis of patient outcomes, and that data will be reported at a later date. 

Charu Aggarwal, MD, MPH, the Leslye M. Heisler Assistant Professor for Lung Cancer Excellence at the Abramson Cancer Center of the University of Pennsylvania in Philadelphia, said this study corroborates previously published research demonstrating that adding plasma-based next-generation gene sequencing to tissue-based gene sequencing improved the detection of actionable mutations.

“While liquid biopsy should not be the only method of diagnosing and treating patients with advanced non–small-cell lung cancer, the results of this study validate that Guardant360 represents a viable non-invasive option to guide therapy in certain select cases,” Aggarwal told Cancer Network.