Abstract 1160: Investigating spatial gene expression profiling in colorectal cancer: Tumor and stroma comparison between primary lesions and matched liver metastases
Authors: Lee Jongwon , Kim Yeseul , Ryu Hyo Seon , Sim Jongmin , Kim Chungyeul , Park Jong Min , Lim Ah-Reum , Kim Jung Sun , Sung Hwa Jung , Guo Xingyi , Choi Jungmin , Choi Jungyoon 
Published: March 2024

Abstract
The nanoString GeoMx® Digital Spatial Profiling (DSP) enables the investigation of spatial assessment of tumors through high-plex profiling at the RNA and protein levels. Recent genomic analyses have revealed the intertumor heterogeneity between primary and metastatic lesions in colorectal cancer (CRC) patients. In CRC with liver metastases, current treatment strategies are mainly based on the parameters of primary tumors, and metastatic heterogeneity is a challenge since molecular heterogeneity contributes to therapeutic resistance. Furthermore, spatial intratumor heterogeneity exists within a single tumor between cancer cells (tumor) and their microenvironment (stroma) in human cancers. However, whether there are distinct spatial gene expression patterns of tumor and stroma between primary lesions and liver metastases remains unclear in CRCs.
We examined 24 formalin-fixed paraffin-embedded tissue samples, including primary lesions and matched liver metastases from 12 patients (6 with synchronous and 6 with metachronous metastases) using NanoString GeoMx® DSP. The best regions of interest (ROI) with the invasive front boundary of the tumor were selected by pathologists. The ROI was segmented into PanCK-positive (tumor) and PanCK-negative (stroma), followed by a collection of indexed oligonucleotides and sequencing on Illumina instrument. Differential expression and pathways enrichment analyses were performed using R BioConductor package standR, limma, and GSEABase. Statistical significances were based on |Log2 fold change| &gt; 1 and Benjamini-Hochberg-corrected P &lt; 0.05. Immune cell abundance was estimated using the SpatialDecon package.
In 12 metastatic patients (mean age, 61 years ± 7 [standard deviation]), liver metastatic stroma was associated with 68 upregulated and 93 downregulated genes compared to the primary stroma, with enrichment of 'Immune response' terms in gene set enrichment analysis (GSEA). A higher proportion of CD4 T memory cells and increased expression of cytotoxic genes (IL7R [2.02-fold], CD3E [1.75-fold], KLRB1 [1.68-fold], and GZMK [1.54-fold]) were observed in liver stroma compared to primary stroma. Conversely, liver metastatic tumors were associated only with 23 upregulated and 6 downregulated genes compared to primary tumors, with 'humoral response' terms enriched in GSEA. Similar patterns were observed in stratified analyses with synchronous and metachronous metastases, although a more prominent ‘immune response’ was observed in synchronous metastatic stroma compared to the primary stroma.
We revealed that higher immune cell proportion and cytotoxic activity were observed in liver metastatic stroma compared to CRC stroma, providing novel insights into a unique etiology and may yield clinical implications for developing targeted treatment modalities for liver metastatic CRC patients.
Citation Format: Jongwon Lee, Yeseul Kim, Hyo Seon Ryu, Jongmin Sim, Chungyeul Kim, Jong Min Park, Ah-Reum Lim, Jung Sun Kim, Hwa Jung Sung, Xingyi Guo, Jungmin Choi, Jungyoon Choi. Investigating spatial gene expression profiling in colorectal cancer: Tumor and stroma comparison between primary lesions and matched liver metastases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1160.