Abstract 5693: Tumor whole-transcriptome sequencing and multiplex immunohistochemistry of immune cell populations in 158 Asian colorectal cancers (2018)

Abstract Background: Colorectal cancer (CRC) is a cancer largely refractory to immune checkpoint inhibition. There is substantial interpatient molecular heterogeneity in colorectal cancer reported from studies on tumor RNA and studies on immunohistochemical analyses of fixed tumor tissue. Several major transcriptomic analyses from microarrays and RNA-seq data have identified major transcriptomic subtypes and major activated pathways and deconvoluted cell-type enrichments. Immunohistochemical (IHC) analyses of formalin-fixed, paraffin-embedded (FFPE) tissue microarrays have identified several different histomorphologic/spatial patterns of immune infiltrates in the tumor microenvironment. Here, we perform large-scale -omic analyses on tumor RNA and multiplex IHC simultaneously on 158 Asian colorectal cancers. Methods: We performed whole-genome sequencing (WGS) (60x tumor, 30x normal) and deep whole-transcriptomic sequencing (RNA-seq) (∼200x106 reads per tumor) on 158 colorectal cancers. To evaluate the spatial patterns of the tumor microenvironment, we constructed a tissue microarray comprising the tumor core, tumor edge and normal adjacent tissue of these 158 CRCs. We performed H&amp;E analyses of the TMA and multiplex immunohistochemistry to simultaneously evaluate 7 markers, i.e., cytokeratin (CK), CD3, CD8, FOXP3, CD68, PD-L1, DAPI, using the an Opal Multiplex fIHC kit. Images were acquired using a Vectra 3 pathology imaging system microscope (PerkinElmer, Waltham, MA, USA). Results: 32 are microsatellite instability high (MSI-H) tumors and 126 are microsatellite stable. (MSS). The major transcriptomic subtypes (Consensus molecular subtypes (CMS 1-4) and CRC assigner (Goblet-like, Enterocyte, Stem-like, Inflammatory, Transit-amplifying subtypes) were identified with good concordance between both classification systems. CMS1 and Inflammatory subtypes were enriched amongst MSI-H tumors. Major oncogenic pathway activations (RAS, Wnt), cell-cycle and inflammatory signatures (interferon-rich) were also identified across the populations. We deconvoluted cell-type enrichment scores from the transcriptomic data to identify different cell-type enrichment patterns across the cohort. On the TMAs, we identified cell type populations and immune infiltrate patterns in the tumor core and invasive edge across the cohort. Correlations across these analyses will be presented at the meeting. Conclusions: There is substantial interindividual variability in the transcriptomic landscape and spatial patterns of immune cell infiltrates in CRCs. Citation Format: Clarinda Wei Chua, Engin Cukuroglu, Elisa Fontana, Si Lin Koo, Joe Poh Yeong, Andy Nguyen, J. Zachary Sanborn, Steve Benz, Emile John Tan, Ronnie Mathew, Ee-Lin Toh, Sarah Boon Ng, Tony Kiat Lim, Anders Jacobsen Skanderup, Shahrooz Rabizadeh, Anguraj Sadanandam, Jonathan Göke, Iain Bee Tan. Tumor whole-transcriptome sequencing and multiplex immunohistochemistry of immune cell populations in 158 Asian colorectal cancers [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 5693.