Abstract A032: Clinical significance of vimentin-positive AXL-expressing circulating tumor cells in advanced non-small-cell lung cancer patients

Abstract

Abstract Purpose: Circulating tumor cells (CTCs) have a potential for the noninvasive decision-making. AXL, a receptor tyrosine kinase is associated with promoting cell proliferation, migration, epithelial-to-mesenchymal transition and drug resistance. We previously reported that the establishment of the detection method of AXL-expressing CTCs by an automated microcavity array (MCA) system incorporating mesenchymal marker vimentin (VM). Here we analyzed the clinicopathological correlation with VM-positive AXL-expressing CTCs in advanced non-small-cell lung cancer (NSCLC) patients. Methods: For detecting CTCs, 6 mL of peripheral blood collected from patients was divided into two portions and used for CTC identification in parallel incorporating markers cytokeratin (CK) and VM, respectively. An automated MCA system was used for enrichment and staining for CD45, DAPI, CK or VM with the additional staining for AXL. DAPI-positive, CK or VM-positive, and CD45-negative cells were defined as CTCs. All statistical analyses were carried out using GraphPad Prism 6 and Mann-Whitney U test, Fisher’s exact test, and rog-rank test were performed accordingly. A p value <0.05 was considered as significant. Results: Twenty advanced NSCLC were enrolled in this clinical study between May and October 2018 at Wakayama Medical University Hospital. Clinical data was tracked until May 2019. The patient characteristics were as follows: median age 70 years (range, 54-82); male 80%; stage III/IV, 10/90%; adenocarcinoma/ squamous cell carcinoma/ other, 65/30/5%. VM-positive single CTCs were detected in 95% of patients (median, 3; range, 0-54) and AXL-expressing VM-positive single CTCs were detected in 60% of patients (median, 1; range, 0-42). AXL-positivity rates in single VM-positive CTCs between patients with previous treatment and those without were compared and patients with previous treatment harbored significantly higher AXL-positivity (p < 0.05). We also assessed the impact of AXL-expressing CTCs on the following treatment in 16 patients from whom we obtained the response data. Cutoff value for segregating partial response + stable disease (n = 13) from progressive disease (n = 3) to the following treatment was 45% of AXL-positivity on VM-positive single CTCs according to receiver operating characteristic curve and p value was 0.071, suggesting the trend favoring AXL-positive CTCs for predicting progressive disease. Progression free survival of treatment following CTC detection was significantly shorter in patients with 45% or more AXL positivity in CTCs (n = 3; median, 41 days) than in those with less than 45% of them (n = 13; median, not reached) (p < 0.01). Conclusion: Our data indicate that detection of AXL-expressing CTCs may have a potential to be indicative of poor prognosis and acquired drug resistance. Citation Format: Mio Ikeda, Yasuhiro Koh, Shunsuke Teraoka, Koichi Sato, Kuninobu Kanai, Atsushi Hayata, Nahomi Tokudome, Hiroaki Akamatsu, Yuichi Ozawa, Keiichiro Akamatsu, Katsuya Endo, Masayuki Higuchi, Masanori Nakanishi, Hiroki Ueda, Nobuyuki Yamamoto. Clinical significance of vimentin-positive AXL-expressing circulating tumor cells in advanced non-small-cell lung cancer patients [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A032. doi:10.1158/1535-7163.TARG-19-A032