Abstract B05: Tissue-compatible EGFR genotyping in tumor-derived extracellular vesicles from malignant pleural effusions.

Abstract

Abstract Purpose: Tumor cells shed extracellular vesicles (TEV) into body fluids. These TEV are a potential source for biomarkers that could be used for non-invasive molecular diagnosis. We investigated whether TEV contain cell-specific mutant EGFR DNA using PC9 cells harboring an exon 19 deletion (E19 del) and PC9/GR cells harboring T790M mutations. In addition, we investigated whether the TEV from malignant pleural effusions can be used for EGFR mutation testing. Materials and Methods: TEV were isolated from the culture medium of PC9 and PC9/GR cells or pleural effusions by serial centrifugations. Isolated TEV were inspected by electron microscopy to determine their size and intact structure. EGFR mutation testing was performed using PNA-mediated clamping PCR. The DNA contents of the TEV from the PC9 and PC9/GR cells were analyzed by array comparative genome hybridization analysis. Results: EGFR genotyping of TEV DNA revealed exactly the same EGFR mutations with cellular DNA in the PC9 and PC9/GR cells. These findings suggest that TEV contain cell-specific mutant DNA that may contain an oncogenic molecular signature such as mutations in EGFR. Testing of the TEV from malignant effusions in eight NSCLC patients yielded the same tissue genotyping results. We observed T790M mutation in addition to the initial E19 del mutation from one patient who developed acquired gefitinib-resistance. Conclusions: In this study, we demonstrated that TEV contain cell-specific oncogenic DNA, including EGFR mutants in the cell line systems examined and pleural effusions. This is the first report detailing how TEV can be used for EGFR mutation testing. Citation Format: Jae Young Hur, Do-Young Choi, Hee Joung Kim, Kyung-Cho Cho, Kwang Pyo Kim, Kye Young Lee. Tissue-compatible EGFR genotyping in tumor-derived extracellular vesicles from malignant pleural effusions. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr B05.