Abstract 1763: A novel RNA in situ hybridization approach highly sensitive for detection of Merkel cell polyomavirus

Abstract

Abstract Background: Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine tumor of the skin. Merkel cell polyomavirus (MCPyV) plays an oncogenic role in the majority of MCC tumors. Detection of MCPyV in MCC tumors has diagnostic utility, and potentially prognostic and therapeutic implications. We investigated whether RNAscope, a novel RNA in situ hybridization (ISH) method for detection of RNA transcripts in tissues at the single-cell/single-molecule level, is useful for MCPyV detection. Methods: We applied an RNAscope probe targeting MCPyV T antigen transcripts on tissue microarrays (TMAs) and full tissue sections encompassing 91 MCC tumors from 75 patients, 14 carcinomas of other types, and various normal tissues. qPCR and immunohistochemistry (IHC) for MCPyV were performed on 58 and 88 cases, respectively. qPCR was also performed on 18 cases of normal skin to establish background levels of MCPyV in non-tumor tissues. Results: RNA-ISH demonstrated the presence of MCPyV in 46.2% (42/91) of cases. A total of 58 samples had data from all the three detection modalities (qPCR, RNA-ISH and IHC). RNA-ISH demonstrated 100% concordance with qPCR results, whereas IHC had a slightly lower concordance (96.6%). RNA-ISH demonstrated higher agreement than IHC among TMA cores from the same case, and between TMA cores and matched full tissue sections. Of samples with background inflammatory cells, 5 of 37 (15.6%) showed moderate nonspecific staining of lymphocytes by IHC, whereas RNA-ISH lacked background. Conclusions: RNA-ISH is comparably sensitive to qPCR for detection of MCPyV, and allows for correlation with tissue morphology. Our findings support RNA-ISH as a highly effective method for MCPyV detection in tumors. Citation Format: Lisha Wang, Paul W. Harms, Nallasivam Palanisamy, Shannon Carskadon, Xuhong Cao, Javed Siddiqui, Rajiv M. Patel, Sylvia Zelenka-Wang, Timothy M. Johnson, Alison Durham, Fengyun Su, Sudhanshu Shukla, Rohit Mehra, Arul M. Chinnaiyan. A novel RNA in situ hybridization approach highly sensitive for detection of Merkel cell polyomavirus [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1763. doi:10.1158/1538-7445.AM2017-1763