Abstract 1811: Correlations of COX2 expressions in circulating tumor cells (CTCs) and response to radiotherapy in head and neck squamous cell carcinoma (HNSCC)

Abstract

Abstract Head and neck squamous cell carcinoma (HNSCC) frequently involves metastasis at diagnosis. Circulating tumor cells (CTCs), captured as “liquid biopsy”, can provide real-time clinical information on prognosis, therapy choice and drug response and resistance. Cyclooxygenase 2 (COX-2), a key enzyme involved in prostaglandin production, participates in inflammatory and neoplastic processes. It is expressed by various tumours and contributes to carcinogenesis. Previous study showed that expression of COX2 in HNSCC tumor tissue samples is associated with clinical response to radiotherapy. The aim of study is to investigate whether expression of COX2 in CTCs could be used as a predict factor to clinical response to radiotherapy.An multiplex RNA in situ hybridization (RNA-ISH) method, named CanPatrol CTC enrichment technique, was used to isolate and categorize CTCs as epithelial, biophenotypic epithelial/mesenchyma, and mesenchymal phenotypes. A total of 51 pateints with HNSCC were enrolled into this study and assessed for CTC levels. Of these 51 pateints, 13 patients were evaluated for COX2 expression in CTCs before and after radiotherapy. The COX2 expression in one CTC or more was defined as positive presence. Primary end point was the overall objective response rate. At baseline, CTCs, ranging from 1 to 15, were identified from 36(70.59%) patients, and the median and mean values were 2 and 3(±3 SD) respectively. No significant correlations were observed between CTCs amounts and clinicopathological parameters. Thirteen (25.49%) patients had ≥2 CTCs both at the beginning and the end of treatment. COX2 expressions was identified in 6(46.15%) patients, which associated with ascending mesenchymal rate afterwards, and indicate a trend of less response to radiotherapy. Compared to 46.15% (6/13) of COX2-positive patients, disease control characterized as decreased CTCs/ mesenchymal CTCs after systemic radiotherapy was obtained in 53.85% (7/13) of COX2-negative (p< 0.05). In summary, COX2-positive CTCs is a promising predictive factor for response to radiotherapy. Citation Format: Feng Wang, Xiaoqi Xie, Zhen Wang, Ping Li. Correlations of COX2 expressions in circulating tumor cells (CTCs) and response to radiotherapy in head and neck squamous cell carcinoma (HNSCC). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1811. doi:10.1158/1538-7445.AM2015-1811