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Background Right-sided colon cancer (CC) has poorer outcome compared to other disease sites 1 and is unresponsive to current treatments.2 3 Inflammation has a well-established relationship within CC, such as through NFkB signalling;4 consisting of two distinct pathways, canonical and non-canonical, regulated by inhibitor of nuclear factor-kB kinase beta (IKKβ) and IKKα, respectively.5 As efforts to inhibit IKKβ have been unsuccessful,6 there is a need to examine if IKKα plays a prognostic role in right-sided CC, delineate the underlying signalling, and investigate if it can be targeted for therapeutic intervention.Methods TemO-Seq TM7 bulk transcriptomic analysis was performed on a cohort of 787 stage I-III CRC patients to examine differences between right- and left-sided CC, and immunohistochemistry (IHC) was used to validate the presence of inflammatory markers. Spatial transcriptomics, GeoMXTM Nanostring, was used to investigate the tumour microenvironments’ role. The results were validated at a protein-level using high-plex sequential immunofluorescence (20-plex) staining by COMETTM Lunaphore platform, together with the SPYRE Immuno-oncology core-panel kit. Patient derived explants (PDEs) were established8 and treated with 1mM fluorouracil (5FU) or 1mM SU1644. Tissue sections from PDE multiblocks were stained for Ki67 expression using IHC, and further 20-plex panels using the COMETTM Lunaphore platform.Results Right-sided CC patients had significantly activated Interferon-alpha/gamma and NFkB pathways at a transcriptomic level, when compared to left-sided disease ( p<0.01). NFkB regulating kinases were assessed at a protein-level, where patients with IKKα high, IKKβ low expressing tumours had the poorest patient outcome (p=0.017) and this was heightened in right-sided disease (p<0.001), when compared to left and rectal cases (figure 1). Spatial transcriptomic GSEA results highlight enriched epithelial to mesenchymal transition (EMT) gene-sets across both the tumour and microenvironment of IKKa-high expressing patients (p<0.05). This was validated at protein-level, by analysing a 20-plex panel of EMT markers in PDE models, treated with a novel IKKa inhibitor SU1644 and standard of care chemotherapy 5FU (figure 2).Conclusions Results illustrate that right-sided CCs present with activated inflammatory signalling, and a central role of NFkB regulation. At a protein-level NFkB signalling, specifically IKKα driven regulation, is significantly associated with poor patient outcome and is heightened in right-sided disease. Across tissue compartments, EMT gene-sets are significantly enriched in these IKKa-high expressing patients. This can be targeted using SU1644, with results demonstrating a reduction in proliferation within a subset of colon tumours upon SU1644 treatment, a potential strategy to target metastasis in right-sided CC.Acknowledgements The authors wish to acknowledge the Glasgow Tissue Research Facility and NHS Greater Glasgow and Clyde biorepository for their help collecting and preparing the tissue for this study. The authors acknowledge the Cancer Research UK Scotland Institute’s Histology Service for invaluable help processing tissue and creating PDE multiblocks used in this study. The authors would like to acknowledge CRUK funding (CANCTA-2022/100006) (JE, NBL, MM) and CSO funding (EPD/22/13) (KAFP, JE, GYL). The authors wish to acknowledge CRUK funding (Scottish Cancer Centre CTRQQR-2021/100006).References Asghari-Jafarabadi M, Wilkins S, Plazzer JP, Yap R, McMurrick PJ. Prognostic factors and survival disparities in right-sided versus left-sided colon cancer. Scientific Reports. 2024; 29:14(1):12306.Baran B, Ozupek NM, Tetik NY, Acar E, Bekcioglu O, Baskin Y. Difference between left-sided and right-sided colorectal cancer: a focused review of literature. Gastroenterology research. 2018;11(4):264.Wang F, Bai L, Liu TS, Yu YY, He MM, Liu KY, Luo HY, Zhang DS, Jin Y, Wang FH, Wang ZQ. Right-and left-sided colorectal cancers respond differently to cetuximab. Cancer Communications. 2015;34(3):1–0.Schmitt M, Greten FR. The inflammatory pathogenesis of colorectal cancer. Nature Reviews Immunology. 2021;21(10):653–67.Karin M. How NF-κB is activated: the role of the IκB kinase (IKK) complex. Oncogene. 1999;18(49):6867–74.Prescott JA, Cook SJ. Targeting IKKβ in cancer: challenges and opportunities for the therapeutic utilisation of IKKβ inhibitors. Cells. 2018;7(9):115.Yeakley JM, Shepard PJ, Goyena DE, VanSteenhouse HC, McComb JD, Seligmann BE. A trichostatin A expression signature identified by TempO-Seq targeted whole transcriptome profiling. PloS one. 2017;12(5):e0178302.Centenera MM, Hickey TE, Jindal S, et al. A patient-derived explant (PDE) model of hormone-dependent cancer. Mol Oncol. 2018;12(9):1608–1622.Ethics Approval The study was approved by the West of Scotland Research Ethics Committee (REC 4: 22/ws/0207) and data are stored in Greater Glasgow and Clyde Safehaven (SH21ON012).Abstract 1259 Figure 1NFkB regulatory kinases- IKKα and IKKβ impact survival of colorectal patients, which is enhanced in right-sided diseaseAbstract 1259 Figure 2Epithelial to mesenchymal transition (EMT) 20-plex panel on patient derived explant tissue, stained and imaged using Lunaphore COMET technology