Characterization of Morreton Virus (MORV) as a Novel Oncolytic Virotherapy Platform for Liver Cancers

Morreton virus (MORV) is a novel oncolytic Vesiculovirus , genetically distinct from vesicular stomatitis virus (VSV). we report that MORV induced potent cytopathic effects in a panel of cholangiocarcinoma (CCA) and hepatocellular carcinoma (HCC) cell lines. In addition, high intranasal doses of MORV were not associated with significant adverse effects and were well tolerated in mice bearing liver tumor xenografts and syngeneic liver cancers. Furthermore, single intratumoral treatments with MORV (1 x 107 TCID50) triggered a robust antitumor immune response leading to substantial tumor regression and disease control in a syngeneic CCA model, using 10-fold lower dose compared to VSV (1 x 108 TCID50). In addition, MORV and VSV both induced prominent tumor growth delay in immunodeficient mice bearing Hep3B hepatocellular carcinoma (HCC) but not in mice bearing HuCCT-1 CCA xenografts. Our findings indicate that wild-type MORV is safe and can induce potent tumor regression in HCC and CCA animal models without adverse events via immune-mediated and immune-independent mechanisms. Further development and clinical translation of MORV as virotherapy for liver cancers are warranted. ### Competing Interest Statement BMN and MJB declare that they filed a patent application for the vectors and their derivatives included in this manuscript. D.G.D. received consultant fees from Bayer, BMS, Simcere, Sophia Biosciences and Surface Oncology and has received research grants from Bayer, Merrimack, Exelixis and BMS. No reagents from these companies were used in this study. All other authors declare no conflict of interest. * ALP : alkaline phosphatase ALT : alanine aminotransferase Anti-VSV-G : anti-vesicular stomatitis virus glycoprotein antibody AST : aspartate aminotransferase ATCC : American Tissue Culture Collection CBC : complete blood count CCA : cholangiocarcinoma CPE : cytopathic effect CTLs : cytotoxic T lymphocytes DMEM : Dulbecco’s Modified Eagle Medium DPBS : Dulbecco’s Phosphate-buffered Saline ELISA : enzyme-linked immunosorbent assay G-MDSCs : granulocytic myeloid-derived suppressor cells GzmB : granzyme B h : human H&E : hematoxylin and eosin HCC : hepatocellular carcinoma HGB : hemoglobin IFN : interferon IFN-α : interferon-alpha IFN-β : interferon-beta IgG1 : immunoglobulin G1 IgG2a : immunoglobulin G2a IgG2b : immunoglobulin G2b IgG3 : immunoglobulin G3 IgGA : immunoglobulin A IgM : immunoglobulin M LDLR KO : HAP-1 LDLR knock-out cells LDLR : low-density lipoprotein receptor m : mouse M-MDSCs : mononuclear myeloid-derived suppressor cells MOI : multiplicity of infection MORV : Morreton virus MTS : 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4 sulfophenyl) 2H-tetrazolium PBS : phosphate buffered saline PD-1 : programmed cell death protein 1 PE : phycoerythrin PT13-D22 : patient 13 treated with VSV-hIFN-β day 22 sample PT14-22 : patient 14 treated with VSV-hIFN-β, day 22 sample qRT-PCR : quantitative real-time polymerase chain reaction RBC : red blood cells RNA : ribonucleic acid RPMI 1640 : Roswell Park Memorial Institute cell culture medium RWA : red cell distribution width RT : Room temperature TAMs : tumor associated macrophages TCID50 : 50% tissue culture infectious dose Vero : African green monkey kidney cell line VSV : vesicular stomatitis virus VSV-hIFN-β : vesicular stomatitis virus expressing human interferon-beta WT : wild type