Abstract 4293: Strategies and resources for applying a quantitative multiplex IHC imaging workflow to characterize immune contexture in solid tumors

Conventional immunohistochemistry (IHC) is a standardized diagnostic technique used in tissue pathology. However, the capacity to label only one marker per tissue section is a critical limitation. Multiplex immunohistochemistry (mIHC) is a powerful imaging technique used in basic, translational research and clinical settings to simultaneously detect the expression of multiple epitopes in a single formalin-fixed paraffin-embedded (FFPE) tissue section, allowing for characterization and quantification of cells while maintaining their spatial location. This technique allows for a comprehensive view of the immune milieu, expression patterns, and interactions between cell types that can help elucidate the complexity of the tumor-immune microenvironment (TiME). Multiplex imaging has emerged as a powerful tool to better understand tumor progression, response or resistance to therapy, and potentially identify predictive biomarkers. However, this technique requires careful tissue considerations and generates enormous amounts of hierarchical data, including single cell marker expressions, locations, and shape features, resulting in complex and challenging analyses. We previously published a validated platform using nine matched primary and recurrent head and neck squamous cell carcinoma (HNSCC) sections stained sequentially with a panel of 29 antibodies identifying malignant tumor cells, and 17 distinct leukocyte lineages and their functional states1. Here, we have optimized and consolidated important considerations, including tissue quality and QC steps necessary for generating high quality data from multiplex imaging studies. We demonstrate strategies for a streamline analytic pipeline using our quantitative workflow developed to characterize immune cells and infiltration patterns within spatial compartments of solid tumors in FFPE tissues, and herein, provide strategies and resources to practically adapt and utilize our analytic mIHC pipeline. 1. Banik, G., et al., Methods Enzymol., 2020 Citation Format: Shamilene Sivagnanam, Courtney M. Betts, Nell Kirchberger, Konjit Betre, Lisa M. Coussens. Strategies and resources for applying a quantitative multiplex IHC imaging workflow to characterize immune contexture in solid tumors. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4293.