Abstract 3711: Procedure establishment of EGFR mutation test with circulating tumor cells of lung cancer by in vitro assay
Authors: Lee Jihyun , Kang Hoin , Kim Min Hyung , Lee Jubi , Kim Hyoyong , Kim Soee , Lee Hae Ung , Lee Hai-Chon , Kim Jung Won 
Published: March 2024

Introduction: Non-small cell lung cancer (NSCLC) is the most common subtype, accounting for approximately 80% of lung cancer. The treatment for NSCLC has significantly improved since the introduction of targeted therapies. Epidermal growth factor receptor (EGFR) mutations are the most frequently found genetic alterations in NSCLC, and deletion of exon 19 is a representative example. Searching for this mutation may provide important clues to the use of EGFR tyrosine kinase inhibitors in NSCLC. So, the detection of EGFR mutation is important step in cancer diagnosis and determining the drug treatment strategy, but the detection of mutation with tissues has limitations such as clinical challenge to poorly accessible tumor tissues before and after treatment. The aim of this study was to explore the feasibility and utility of implementation of EGFR molecular testing from circulating tumor cells (CTC) in NSCLC. Here, we developed and optimized the procedure of mutated EGFR detection in CTC after isolation with CytoGen’s Smart BiopsyTM CTC isolator by cobas® EGFR Mutation Test. This EGFR mutation test in CTC showed the potential to overcome the limitations of tissue biopsy with high sensitivity and specificity in an in vitro assay.

Method: PC-9 cells were used the positive control of EGFR mutation (EGFR exon 19 deletion). Limit of detection (LOD) was performed with PC-9 cells (200 cells to 5 cells, 6 points) spiked into blood sample (5mL, healthy donor) to mimic CTC in the blood of lung cancer patient. CTC were isolated from spiked samples using CytoGen’s Smart BiopsyTM CTC isolator, subsequently cobas® EGFR Mutation Test was carried out to detect of EGFR mutation.

Results: In in vitro experiments of recovery test using cell lines spiked into blood from healthy donor, the recovery rate of CytoGen’s Smart Biopsy TM CTC isolator showed over 80%. As a result of LOD test, EGFR exon19 deletion mutation of PC-9 cells was clearly detected even in the smallest number of cells were spiked into blood (5 cells in 5mL blood) and was not detected at all in the negative controls. The result suggested that CytoGen’s Smart Biopsy TM CTC isolator can isolate CTC with high recovery rate and apply the test of oncogenic mutations including EGFR mutation in CTC.

Conclusions: Confirmation of EGFR mutation is important step in the diagnosis and selection of optimal drug for cancer patients. However, tissue biopsy has several limitations such as difficulties to get tissue samples and inaccurate information due to invasive method and tumor heterogeneity. Detection of EGFR mutation in CTC might overcome and make up for limitations of tissue biopsy. In this study, we optimized the EGFR mutation detection procedure of intact live CTC isolated by CytoGen’s Smart BiopsyTM CTC isolator.

Citation Format: Jihyun Lee, Hoin Kang, Min Hyung Kim, Jubi Lee, Hyoyong Kim, Soee Kim, Hae Ung Lee, Hai-Chon Lee, Jung Won Kim. Procedure establishment of EGFR mutation test with circulating tumor cells of lung cancer by in vitro assay [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 3711.