Abstract 5135: Detection of IFN induced PDL1 expression by combined in situ RNA analysis and protein profiling from a single FFPE slide

• Published in: Cancer research (Chicago, Ill.) Vol. 76; no. 14_Supplement; p. 5135
• Main Authors: Au, Qingyan, Nguyen, Kathy, Lazare, Michael S, Moler, Edward J, Hoe, Nicholas
• Format: Journal Article
• Language: English
• Published: 15-07-2016
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2016-5135

PD1 ligands (PDL1) are often upregulated on the cell surface of many different tumors. The primary role of PDL1 in cancer is to inhibit T-cell mediated immune response. Two general mechanisms for PDL1 expression on tumor cells have been proposed. Innate immune resistance, in which PDL1 expression is induced by the constitutive oncogenic signaling, and adaptive immune resistance, in which PDL1 expression is induced by T-cells releasing interferon- (IFN) and activating the STAT signaling pathway. In order to differentiate between these two mechanisms, IFN mRNA expression is measured as an effective alternative to detecting IFN protein. Detection of cytokines by IHC is challenging as secreted proteins are widely diffused and the associated staining pattern appears to lack cellular specificity. RNAscope RNA in situ hybridization (ISH) assay is utilized to measure Interferon- (IFN) mRNA expression, and MultiOmyxTM multiplexed assay (demonstrated to stain up to 60 protein biomarkers) is utilized to measure CD3, CD4, CD8, CD56, CD68, PD1, and PDL1 protein expression. In this study, combined MO and RNAscope ISH assays, enabled identification of individual cells with characteristic mRNA and protein expression profile.