Myxoma Virus Expressing LIGHT (TNFSF14) Pre-Loaded into Adipose-Derived Mesenchymal Stem Cells Is Effective Treatment for Murine Pancreatic Adenocarcinoma

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a weakly immunogenic fatal neoplasm. Oncolytic viruses with dual anti-cancer properties—oncolytic and immune response-boosting effects—have great potential for PDAC management. Adipose-derived stem cells (ADSCs) of mesenchymal origin were infected ex vivo with recombinant myxoma virus (MYXV), which encodes murine LIGHT, also called tumor necrosis factor ligand superfamily member 14 (TNFSF14). The viability and proliferation of ADSCs were not remarkably decreased (1–2 days) following MYXV infection, in sharp contrast to cells of pancreatic carcinoma lines studied, which were rapidly killed by the infection. Comparison of the intraperitoneal (IP) vs. the intravenous (IV) route of ADSC/MYXV administration revealed more pancreas-targeted distribution of the virus when ADSCs were delivered IP to mice bearing orthotopically injected PDAC. The biodistribution, tumor burden reduction and anti-tumor adaptive immune response were examined. Bioluminescence data, used to assess the presence of the luciferase-tagged virus after IP injection, indicated enhanced trafficking into the pancreata of mice bearing orthotopically-induced PDAC, as compared to tumor-free animals, resulting in extended survival of the treated PDAC-seeded animals and in the boosted expression of key adaptive immune response markers. We conclude that ADSCs pre-loaded with transgene-armed MYXV and administered IP allow for the effective ferrying of the oncolytic virus to sites of PDAC and mediate improved tumor regression.