Abstract 3725: Exosomal Galactin-3 promotes pre-metastatic niche formation that accelerates peritoneal metastases of gastric adenocarcinoma

Abstract

Abstract Peritoneal carcinomatosis (PC) in gastric adenocarcinoma (GAC) lead to a short median survival (≤6 months). Pre-metastatic niche (PMN) formation, in a distant organ to prepare for tumor seeding and colonization, has long been recognized. However, the precise molecular and mechanistic contributions of exosomes in PMN formation of PC remain unclear. We identify that exosomes promote PMN formation in the peritoneal cavity by patient-derived orthotopic mouse model. Using an in-depth proteomic profiling of paired ascites cells and ascites-derived exosomes from PC patients, we discover that Galectin-3 as the exosomal payload is responsible for PC by promoting PMN formation in both patient-derived orthotopic model and syngeneic mouse model. Inhibition of exosomal Galectin-3 reverses PC. Furthermore, exosomal Galectin-3 activates cancer-associated fibroblasts (CAFs), which further activate the CXCL12/CXCR4 axis to orchestrate the immunosuppressive PMN. Simultaneous inhibition of exosomal Galectin-3, CXCR4, and PD-1 leads to tumor regression and durable anti-tumor responses. Thus, this study provides a rationale for the novel clinical strategy for GAC patients with PC. Citation Format: Yibo Fan, Shumei Song, Melissa Pool Pizzi, Katsuhiro Yoshimura, Jody V. Vykoukal, Samir Hanash, Jaffer Ajani. Exosomal Galactin-3 promotes pre-metastatic niche formation that accelerates peritoneal metastases of gastric adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3725.