Routine Clinical Liquid Biopsy Testing for Solid Tumors Delivers the Promise of Minimally Invasive Detection of Genomic Variants With a Faster Turnaround Time.

Abstract

Purpose: A 70-gene liquid biopsy (LB) panel (LBP-70) was implemented at our institution to identify genetic alterations in the plasma of patients with solid tumors. We report the clinical utility of LBP-70 in a retrospective study of 1,243 consecutively tested patients.

Materials and methods: Electronic medical records were reviewed for relevant clinicopathologic and radiologic information and preanalytical variables, including circulating cell-free DNA yield. The clinical utility of the LBP-70 assay was evaluated on the basis of its ability to identify major tumor drivers and/or targetable alterations and the concordance of the LBP-70 results with tissue genotyping and radiologic findings.

Results: Positive LB findings were reported in 75% of patients, ranging from 67% to 85% among various tumor types and 60% to 77% in different tumor stages within an average of seven workdays. The mutant allele frequency (AF) ranged from 0.1% to 90%, and 50% of the variants were detected at AF <2%. Overall, LBP-70 provided clinically informative findings in 87% of the patients. In patients with non-small cell lung cancer (NSCLC) and colorectal cancer without tissue specimens, LBP-70 identified informative findings in 74% of patients, including EGFR exon 18-21 mutations in 22% of patients with NSCLC and RAS and/or BRAF V600E mutations in 44% of patients with colorectal cancer. LBP-70 results showed 62% concordance with tissue genotyping and 79% concordance with radiologic findings.

Conclusion: The results of this study demonstrated the clinical utility of LBP-70 in identifying clinically informative findings. LBP-70 is an alternative to tissue-based tumor genotyping and provides a more rapid method for detecting actionable genetic alterations.