Rapid detection of non-small cell lung cancer driver mutations using droplet digital polymerase chain reaction analysis of bronchial washings: a prospective multicenter study.

Background: Molecular profiling of non-small cell lung cancer (NSCLC) is crucial for personalized treatment, but obtaining adequate tumor tissue can be challenging. This study evaluated the utility of droplet digital polymerase chain reaction (ddPCR) analysis of bronchial washings (BWs) and serum for detecting driver oncogene mutations in NSCLC patients, comparing its performance to standard tissue genotyping methods.

Methods: In this prospective, multicenter study conducted at two university hospitals in Yokohama, Japan, 73 treatment-naïve NSCLC patients underwent bronchoscopy with BW collection and blood sampling between October 2022 and April 2024. ddPCR was performed on BW and serum samples to detect epidermal growth factor receptor (EGFR; L858R, exon 19 deletions, G719X), KRAS (G12/13), and BRAF (V600E) mutations. Results were compared with standard tissue genotyping methods, including AmoyDx and Oncomine Dx Target Test (DxTT) assays. Turnaround time (TAT) for results was also assessed. The study protocol was approved by the institutional review boards, and all participants provided informed consent.

Results: ddPCR analysis of BW samples showed high concordance with tissue genotyping, detecting EGFR mutations in 31.5% of cases (identical to tissue). For common EGFR mutations (L858R and exon 19 deletions), BW genotyping demonstrated 100% sensitivity and 98.0% specificity compared to tissue. TAT was significantly shorter for BW ddPCR compared to tissue genotyping (4.4±1.8 vs. 20.4±7.7 days, P<0.001). Serum ddPCR showed lower sensitivity (7.8% vs. 33.3% for EGFR mutations) compared to tissue genotyping, with detection associated with the presence of bone metastases. KRAS and BRAF mutations were detected at similar rates in BW and tissue samples, but at lower rates in serum.

Conclusions: ddPCR analysis of BWs demonstrates high accuracy and rapid TAT for detecting common driver mutations in NSCLC. This approach represents a promising alternative to tissue biopsy for molecular profiling, potentially expediting treatment decisions. While serum ddPCR showed limited utility, it may complement tissue genotyping in specific clinical scenarios.