Ain, Q. u.; Frei, N.; Khoshiwal, A. M.; Stougie, P.; Odze, R.; Ferri, L.; Duits, L. C.; Bergman, J.; Stachler, M. D.

To date, characterization of the Barrett\'s esophagus (BE) immune microenvironment in patients with known progression status to determine how the microenvironment may influence BE progression to esophageal adenocarcinoma (EAC) has been understudied, hindering both the biological understanding of progression and the development of novel diagnostics and therapies. Therefore, this study\'s aim was to determine if highly multiplex interrogation of the immune microenvironment can be performed on endoscopic formalin-fixed, paraffin-embedded (FFPE) samples utilizing the Nanostring GeoMx digital spatial profiling (GeoMx DSP) platform. We performed spatial proteomic analysis of 49 proteins expressed in the microenvironment and epithelial cells of histologically identical FFPE endoscopic biopsies from patients with non-dysplastic BE (NDBE) who later progressed to high-grade dysplasia (HGD) or EAC (N=7) or from patients who after at least 5 years follow up did not (N=8). In addition, we performed RNA analysis of 1,812 cancer related transcripts on a series of three endoscopic mucosal resections containing regions of normal tissue, BE, dysplasia (DYS), and EAC. Our primary goal was to determine feasibility of this approach and begin to identify the types of specific immune cell populations that may mediate the progression of pre-neoplastic BE to EAC. Spatial proteomic and transcriptomic profiling with GeoMx DSP showed reasonable quality metrics and detected expected differences between epithelium and stroma. Several proteins were found to have increased expression within non-dysplastic BE biopsies from progressors compared to non-progressors, suggesting further studies on the BE microenvironment are warranted.