High tissue expression of Flt3L is linked to higher infiltration of immune cells in patients with high-grade GEP-NEN

#3387

Introduction: The clinical management of gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) remains challenging due to disease heterogeneity. We have recently shown that mRNA expression of the immunostimulatory cytokine FMS-like tyrosine kinase 3 ligand (Flt3L) in tumor tissue is a prognostic biomarker in high-grade GEP-NEN patients. However, a direct link between Flt3L expression and the presence of proinflammatory immune cells in the tumor microenvironment (TME) of GEP-NEN is still missing.

Aim(s): We analysed the immune cell content and composition in the TME of GEP-NEN tissues with known Flt3L mRNA expression levels, initially focusing on dendritic cells (DCs) and T cells that are known to be influenced by Flt3L expression.

Materials and methods: We performed multiplex immunofluorescence staining for immune cell markers of classical DCs Type 1 (cDC1) and 2 (cDC2) as well as T cells on cryosections of 30 patients with high-grade pancreatic and gastric NEN, for which Flt3L expression data were available.

Conference:

Presenting Author: Werner W

Authors: Werner W, Detjen K, Bruneau A, Wiedenmann B, Tacke F,

Keywords: NET, Flt3L, DC, dendritic cell, biomarker, immune response, immune microenvironment,