Multi-gene Liquid Biopsy to Detect Resistance to First-line Osimertinib in Patients With EGFR-mutated Lung Adenocarcinoma.

Abstract

Osimertinib is currently used as a first-line treatment for EGFR-mutated non-small cell lung cancer, and the emergence of drug resistance poses a substantial challenge. Liquid biopsy with a multi-gene panel can examine both the molecular mechanisms and possibility of early resistance diagnosis. We used a molecular barcode library construction kit (Archer® LiquidPlex™) that allowed the analysis of multiple cancer-related genes using cell-free DNA from the plasma samples of patients. We collected plasma from 17 consecutive patients with lung adenocarcinoma at our hospital at various time points and cell-free DNA was extracted and subjected to LiquidPlex analysis. Plasma DNA concentration was not associated with the presence or absence of resistance to osimertinib. The pathological mutations detected using next-generation sequencing in the resistant specimens were in MAP2K1, PIK3CA, TP53, BRAF, and EGFR. Among the recurrent cases, EGFR mutations identified at the initial diagnosis were detected within 6 months before relapse confirmation in four cases (average 88 days). Many of the recurrent cases without detection of known EGFR mutations in the liquid biopsy showed a longer interval between the detection of relapse and the last blood draw for the liquid biopsy (average 255 days). Frequent liquid biopsies are useful for identifying known EGFR mutations as markers for early detection of relapse. Several cancer driver mutations were observed, suggesting a variety of mechanisms of resistance in first-line osimertinib-treated lung adenocarcinoma.