Abstract 1029: Role of PCDHGA12/PRRX1 Methylation for the Diagnosis of Lung Cancer Using Bronchial Washing Fluid

Abstract Bronchoscopy is a frequently used initial diagnostic procedure for patients with suspected lung cancer (LC). Cytological examinations of bronchial washing (BW) samples, obtained during bronchoscopy, often yield inconclusive results in the diagnosis of LC. Aberrant DNA methylation has previously been shown to be a useful biomarker for LC. DNA methylation analysis in BW specimens could serve as a valuable clinical adjunct to cytology. In this study, to identify potential methylation biomarkers for LC, methylation microarray analyses were performed on primary tumors and compared with adjacent non-tumor tissues of 13 patients with LC at various stages (I - IV). A stepwise validation process using bisulfite-pyrosequencing of cell lines and tissues identified six methylated genes (ADAMTS20, FOXC2, NKX2-5, OLIG3, PCDHGA12, and PRRX1) associated with LC. To assess methylation in BW samples, a highly sensitive and accurate 3-plex Linear Target Enrichment (LTE)-quantitative methylation-specific PCR (qMSP) in a single closed tube was developed. Clinical validation was performed using BW samples from patients with LC (n = 68) and non-LC (benign) (n = 33) and identified PCDHGA12 and PRRX1 methylation as the best performing marker combination for detecting LC. The 2-marker combination exhibited a sensitivity of 82.4% and a specificity of 87.9%, with an area under the curve of 0.891. Notably, its sensitivity was 100% for small cell LC. The 2-marker combination had a positive predictive value of 93.3% and a negative predictive value of 70.7%. Its sensitivity outperformed cytology. The methylation status of the 2-marker showed no correlation with gender, age or stage, but was associated with tumor location and histology. In conclusion, we identified PCDHGA12 and PRRX1 methylation as high potential biomarkers for LC diagnosis. This study shows that these biomarkers could be used as a diagnostic adjunct to cytology in the clinical practice for diagnosing LC in BW specimens. Citation Format: Ji Woong Son, Tae Jeong Oh, Minheyok Lee, Chang Ryul Park, Sungwhan An. Role of PCDHGA12/PRRX1 methylation for the diagnosis of lung cancer using bronchial washing fluid [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1029.