Abstract 5652: Validation of novel InSituPlex™ technology utilizing standard chromogenic IHC and multiplexed tyramide-based immunofluorescence
Authors: Katir Patel, Courtney Hebert, Jamie Buell, Sean Downing
Journal: Cancer Research (2018)

Abstract Introduction: The demands of today's immuno-oncology research has driven the development of more robust tools to interrogate the tumor microenvironment, specifically using multiplex immunofluorescence (mIF). Multiplex immunofluorescence allows investigators to visualize multiple biomarkers in tissue sections while preserving spatial context. The current gold standard of immunohistochemistry is “brown” staining using DAB with a hematoxylin counterstain. In recent years, multiplex immunofluorescence has been accepted in the field using tyramide molecules (TSA) that permanently fix fluorescent dyes to the tissue. Consequently, tissue integrity is compromised and cannot be utilized in additional forms of analysis. In addition, high-level plexing using TSA requires the use of highly specialized and costly imaging equipment. Here we validate a novel technology, InSituPlex™, utilizing DNA barcoding of antibodies and the detection of markers using simple DNA hybridization techniques. InSituPlex allows for high-leveling of multiplexing, preservation of tissue integrity for additional analyses, and implementation on a variety of commonly used imaging platforms. Methods: Performance of the InSituPlex technology was assessed using 15 immuno-oncology relevant markers (CD3, CD4, CD8, CD20, CD25, CD68, CD163, FoxP3, Granzyme B, Ki67, PD1, PD-L1, pan-cytokeratin, Sox10, and TTF1). Each marker was benchmarked by performing a single-plex DAB chromogenic IHC and an immunofluorescence assay. Antibodies to be used for InSituPlex testing were first conjugated to unique DNA barcodes and the resulting conjugates were assessed utilizing the previously described assays to ensure equivalent performance of the InSituPlex conjugate to unconjugated antibodies. The performance of the complete InSituPlex assay was evaluated using InSituPlex HRP labelled imaging strands and the newly barcoded antibodies. InSituPlex vs. DAB/TSA performance was compared across platforms. All staining was performed manually and on the Leica BOND RX autostainer. Images were acquired across multiple imaging platforms, including the Leica VERSA whole slide scanner, and image analysis was performed using HALO from Indica Labs. Results: All antibodies performed equally well across all the staining methodologies as assessed qualitatively. Quantitatively, cell counts were performed on serial sections. Statistical analysis comparing InSituPlex to standard chromogenic and immunofluorescent assays across all 15 antibodies did not yield any significance (p-value &amp;gt; 0.1). Conclusions: Detection of relevant immune and cancer related markers utilizing InSituPlex technology is equivalent to standard chromogenic IHC and immunofluorescent assays. Citation Format: Katir Patel, Courtney Hebert, Jamie Buell, Sean Downing. Validation of novel InSituPlex™ technology utilizing standard chromogenic IHC and multiplexed tyramide-based immunofluorescence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5652.