Abstract 427: Detection and molecular characterization of circulating tumor cells in advanced head and neck squamous cell carcinoma

Abstract

Abstract Malignant properties of tumor cells are genetically and epigenetically altered during tumor development and progression. Moreover, tumor cells rapidly change to treatment resistant phenotype by various therapeutic pressures, and not only become more heterogeneous but also possess metastatic potential. Detection and characterization of circulating tumor cells (CTCs) in the bloodstream of cancer patients have been currently remarked as a valuable tool for real-time evaluation of tumor tissue with phenotypic heterogeneity in the diagnosis and treatment of various cancers, however these have been still challenging. In the present study, we investigated the presence of CTCs and their molecular characterization by the combination of microfiltration system and RT-qPCR method. Peripheral blood samples were collected from 30 patients with advanced head and neck squamous cell carcinoma (HNSCC) and passed through two CellSieveTM microfilters using a low-pressure filtration system. The existence of CTCs collected from the first filter was determined by the expression of epithelial-related genes (KRT19, EPCAM, EGFR, or MET), then the expression of cell proliferation (PIK3CA and CCND1)-, EMT (SNAI1 and VIM)-, cancer stemness (CD44, NANOG, and ALDH1A1)-, and immune regulation (CD47, CD274, and PDCD1LG2)-related genes was analyzed for molecular characterization of CTCs. The gene expression in cells collected from the second filter was used for normalization of target genes. Sixteen (53.3%) of 30 patients were positive for at least one epithelial-related gene. Interestingly, the number of patients with locoregional recurrence or distant metastasis in 16 CTC-positive patients was 7 (43.8%) or 5 (31.3%); whereas that in 14 CTC-negative patients was 2 (14.3%) or 1 (7.1%), respectively. The gene expression profile in CTCs collected from 16 CTC-positive patients has revealed remarkable heterogeneity between HNSCC patients. Of 16 CTC-positive patients, PIK3CA was overexpressed in 56.3%, CCND1 in 43.8%, SNAI1 in 62.5%, VIM in 43.8%, CD44, in 50.0%, NANOG in 31.3%, ALDH1A1 in 56.3%, CD47 in 62.5%, CD274 in 37.5%, and PDCD1LG2 in 31.3%. Our results suggest that CTCs may play an important role in locoregional recurrence as well as distant metastasis in HNSCC. Further molecular profiling at the single-cell level of CTCs is needed to clarify the clinical significance of molecular phenotype of CTCs. Citation Format: Hiroe Tada, Hideyuki Takahashi, Hiroki Ishii, Yuki Kuwabara-Yokobori, Masato Shino, Kazuaki Chikamatsu. Detection and molecular characterization of circulating tumor cells in advanced head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 427.