Abstract

Background: Intracholecystic papillary-tubular neoplasm (ICPN) is a preinvasive neoplasm and precursor of gallbladder carcinoma with a reported incidence of <0.5%, and although rare, invasive gallbladder carcinoma is seen in more than half of these cases. Molecular and immune features of ICPNs associated with invasive gallbladder adenocarcinoma (ICPN_GBC) have not been well characterized. Our aim is to elucidate the differential immune gene expression signatures and other biological pathways between conventional gallbladder adenocarcinoma (GBC) and ICPN_GBC. Design: Sixty FFPE tumor samples (GBC, 40; ICPN_GBC, 20) were selected from patients who underwent cholecystectomy from 2007-2015 and submitted for immune gene sequencing using HTG Precision Immuno-Oncology Panel. We evaluated the differential gene expression profile of 1392 genes and HTG signatures between GBC and ICPN_GBC, and other clinicopathological features including age, sex, histologic grade, tumor size, pT category, lymphovascular invasion and overall survival (OS) status. A P value ≤ 0.05 was regarded as significant. Results: We found 128 differential expressed genes between GBC and ICPN_GBC (P<0.05). ICPN_GBC presented higher gene signature scores of T helper type 1 cells (P=0.008). In contrast GBC, showed upregulation of genes related to an immunosuppressive microenvironment with higher signature scores of regulatory T cells, M2 macrophages and dendritic cells (all P<0.05). ICPN_GBC displayed a relatively higher expression of genes involved in cell cycle, metabolism, DNA repair and cell- cell adhesion molecules (CDH1, Nectin2, OCLN and EpCAM), while GBC exhibited upregulation of genes encoding for cell- extracellular matrix adhesion molecules (ITGA5, LGALS1 and CD99). Notably, a higher signature score of T helper type 1 cells was positively correlated with tumor size (P=0.047, r=0.41), fibroblast signature was inversely correlated with tumor size (P=0.0064, r=0.54), and T regulatory cell signature was higher in pT3-pT4 compared to pT1-pT2 tumor categories (P=0.036). MS4A2 gene was associated with a better OS (P<0.0001).