Bronchial washing fluid supernatant serves as a novel liquid biopsy specimen for genome profiling in advanced non-small cell lung cancer

Abstract

Background: Tumor tissue is the primary substrate for molecular testing in advanced lung cancer. However, obtaining sufficient tissue samples from biopsy for molecular testing often be challenging for some patients. Bronchial washing fluid supernatant (BWFS), which contains tumor-derived DNA, may serve as a supplement for genotyping. The aim of this study is to assess the efficacy and precision of detecting gene alterations in BWFS samples and evaluate their clinical potential.

Patients and methods: Thirty-eight stage III-IV non-small cell lung cancer (NSCLC) patients were prospectively enrolled between June 2022 and May 2024. The BWFS, matched tumor tissue (TIS), and plasma (PLA) from each patient were collected simultaneously, and all samples were subjected to targeted next-generation sequencing (NGS) of 520 cancer-related genes or 168 cancer-related genes.

Results: In the cohort of 38 patients, 28 had simultaneous NGS results from three distinct samples. compared with PLA, BWFS contains more abundant tumor-derived DNA and exhibited a higher maximum allelic frequency (max_AF) and elevated mutation detection rate (BWFS: 96.4 %, PLA: 85.7 %), in concordance with TIS (BWFS: 96.4 %, TIS: 100 %). A total of 536 mutation events were detected from the three sample types (TIS: 225, BWFS: 209, PLA: 102). Using TIS as the gold standard, BWFS demonstrated superior sensitivity compared to PLA (78.22 % vs. 36 %). For different variations, copy number variations (CNVs) and fusions were more challenging to detect in PLA compared to BWFS. The estimates of tumor mutational burden (TMB) based on TIS and BWFS were highly correlated (Pearson r = 0.97).

Conclusion: Our study is the first to demonstrate that BWFS performs comparably to matched TIS and superiorly to PLA for genotyping advanced NSCLC via NGS. BWFS emerges as a valuable specimen, particularly in patients with insufficient tumor tissue.

Keywords: Bronchial washing fluid supernatant; Genome profiling; Liquid biopsy; NSCLC; Next-generation sequencing.