Abstract LB-351: Investigating the role immunogenomics in normal adjacent to tumor tissue (NAT) versus tumor in prognostication of stage matched colorectal cancer
Authors: Ahluwalia Pankaj Kumar , Mondal Ashis , Ahluwalia Meenakshi , Sahajpal Nikhil , Njau Allan , Okechukwu Nwogbo , Kota Vamsi , Kolhe Ravindra 
Published: September 2020

Colorectal cancer (CRC) is the third most common type of cancer affecting nearly 1.4 million individuals every year. In the past two decades, rapid advancements in genomics and transcriptomics have uncovered various molecular profiling methods that are assisting in the design of personalized treatment strategies for cancer patients. In this study, we attempted to identify differentially expressed genes in tumor and NAT for its clinical significance in CRC. We designed a novel 88 gene-expression panel consisting of immune and cancer driver genes based on literature. Under IRB approved protocol, 28 FFPE samples (tumor = 14, NAT = 14) were acquired from pathology archives. H&E slides were examined and by using macrodissection, regions with &gt;95% of tumor or NAT region were identified by two expert pathologist. Total RNA was isolated from these tissue sections and quantified through Nanodrop method. The expression level of the genes was measured using NanoString digital quantification system. Pairwise comparisons by Wilcoxon rank-sum test identified significant gene perturbations in the NAT compared to the tumor. IL-15, GATA3, CCR4, CCL13 and IFNA1 genes were highly expressed in NAT (p &lt;0.05). Comparatively, PKM, E2F1, GTF3A, MCM4, MMP14 genes were expressed at a higher amount in tumor compared to NAT (p &lt;0.05). Unsupervised hierarchical clustering identified two distinct clusters belonging to tumor and NAT. String DB analysis further identified immune genes as a dominant node with higher expression in NAT. Comparatively, tumors showed higher expression of genes belonging to the cell growth pathway. This observation identifies the predominance of “cold” immune status of tumors compared to immunologically active adjoining regions. Interestingly, the expression of IKBKB (Inhibitor of NFKB Kinase Subunit Beta) was found to be lower in patients that received chemotherapy. IKBKB helps in the activation of NFKB complex by phosphorylation and dissociation of the inhibitor of NFKB. This study has identified immunologically active tumor adjacent normal regions and the variable expression of IKBKB in patients who received chemotherapy. The clinical significance of these findings will be further explored in large patient cohorts. Further, there is a need to comprehensively explore more functionally relevant genes in NAT regions that can have prognostic and predictive potential. The expanded understanding of differential gene expression of NAT compared to the tumor might assist in the design of novel combinatorial therapies.

Citation Format: Pankaj Kumar Ahluwalia, Ashis Mondal, Meenakshi Ahluwalia, Nikhil Sahajpal, Allan Njau, Nwogbo Okechukwu, Vamsi Kota, Ravindra Kolhe. Investigating the role immunogenomics in normal adjacent to tumor tissue (NAT) versus tumor in prognostication of stage matched colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-351.