The International Association for the Study of Lung Cancer (IASLC) has released recommendations for the use of liquid biopsies to inform the care of patients with advanced non-small cell lung cancer (NSCLC), offering guidance on the clinical collection, processing, and genetic analysis of tumor DNA from peripheral plasma samples.1
These tests can be used for initial molecular diagnosis and for detection of acquired drug resistance mutations.
“Liquid biopsy and its subsequent molecular analysis is a powerful tool that can determine the patient’s molecular tumor profile in order to determine the best therapeutic option and can be applied as an alternative to tissue testing in cases where tumor testing is not possible or tissue is not adequate,” reported statement coauthor Fred Hirsch, MD, PhD, the chief executive officer of the IASLC, in a press release.2
Circulating tumor DNA (ctDNA)-based gene tests for EGFR mutations are already used and tests for ALK and other mutations will soon follow, the authors noted. Other liquid biopsy techniques are in development, including ones that capture circulating tumor cells, platelet RNA, and ctRNA, but these are not yet validated or well understood.
“The IASLC Statement was very comprehensive,” said Edward S. Kim, MD, Chair of Solid Tumor Oncology at the Levin Cancer Institute in Charlotte, North Carolina, who was not an author of the statement paper.
“[The statement] gives guidance around the world about everything from how to collect the specimens to how to process them, the acceptable platforms to run them on and which types of driver alterations or biomarkers are best utilized, or with which we have the most experience,” he continued.
The IASLC statement recommends that liquid biopsies be obtained from patients for whom it is very difficult or risky to perform traditional tumor tissue biopsy. Biopsying metastatic bone tumors can be challenging, for example.
“It’s a natural segue from tissue to blood or serum to help us diagnose patients, determine treatment recommendations using biomarkers, and also assess if a therapy should be continued or stopped,” Dr Kim said. “Down the road, we may be able [use liquid biopsy] to avoid overtreatment of patients.”
The multidisciplinary team of authors recommended the use of “double-spin” plasma isolation and plasma-extracted ctDNA testing, and that plasma extraction occur within 2 hours of blood draw when EDTA tubes are used, or 3 days for preservative tubes. Blood should never be frozen before plasma extraction, they noted. Two standard 10 mL tubes should be used at blood draw. Validated, quantitative PCR (qPCR)-based analysis of EGFR and other targeted mutations is “acceptable,” the authors concluded.