Abstract LB238: Multiplex immunohistochemistry profiling with UltraPlex IHC on FFPE lung cancer provides a fast and robust staining platform compatible with clinical laboratory workflows

A wide range of technologies are now available to perform multiplex immunofluorescence(mxIF) to examine the tumor immune microenvironment in FFPE tissue sections, offering the potentialto reveal signatures of anti-tumor immune response. However, mxIF assay performance is often limitedby autofluorescence and other artifacts, particularly in lung and prostate cancer samples. These artifactscan frustrate detection even using dedicated instrumentation to obtain images and advanced softwareto identify and measure the different biomarkers. Compared to immunofluorescence,immunohistochemistry (IHC) displays far less background and uses tools readily available in anypathology lab, but IHC has been traditionally difficult to multiplex especially regarding co-localization oncells. Recently, Cell IDx has overcome this barrier by developing UltraPlex™ multiplex IHC (mxIHC),where we leverage Cell IDx9s antibody hapten-tagging technology to enable independent detection of 3-4 primary antibodies from any species on a single tissue section, using different chromogen colors todistinguish each biomarker. In this study of various NSCLC tumors, we display how mxIHC can define theTME while maintaining staining integrity. Using UltraPlex™ mxIHC, we demonstrate a useful clinicalchromogenic triple stain of CD8, PD-L1, and panCK with the ability to produce accurate quantitation forphenotype subsets. Our result show that UltraPlex™ mxIHC on FFPE tissue sections can provideincreased confidence for multiplexing on challenging tissues while requiring only conventionallaboratory methods and apparatus. Citation Format: Helen Tighe-Snyder, Matt Levin, Zohreh Akhananaghdam, Yanfei Jiang, David Schwartz. Multiplex immunohistochemistry profiling with UltraPlex IHC on FFPE lung cancer provides a fast and robust staining platform compatible with clinical laboratory workflows [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB238.