A novel chimeric oncolytic virus vector for improved safety and efficacy in 1 hepatocellular carcinoma 2 3 Running title : A chimeric virus for improved oncolytic therapy of HCC

34 35 Oncolytic viruses represent an exciting new aspect of the evolving field of cancer 36 immunotherapy. We have engineered a novel hybrid vector comprising vesicular 37 stomatitis virus (VSV) and Newcastle disease virus (NDV), named rVSV-NDV, 38 wherein the VSV backbone is conserved, but its glycoprotein has been replaced by 39 the hemagglutinin-neuraminidase (HN) and the modified, hyperfusogenic fusion (F) 40 envelope proteins of recombinant NDV. As opposed to wild-type VSV, which kills 41 cells through a classical cytopathic effect, the recombinant virus is able to induce 42 tumor-specific syncytia formation, allowing for efficient cell-to-cell spread of the virus 43 and a rapid onset of immunogenic cell death. Furthermore, the glycoprotein 44 exchange substantially abrogates the off-target effects in brain and liver tissue 45 associated with wildtype VSV, resulting in a substantially enhanced safety profile, 46 even in immune-deficient NOD-SCID mice which are highly susceptible to wild-type 47 VSV. Although NDV causes severe pathogenicity in its natural avian hosts, the 48 incorporation of the envelope proteins in the chimeric rVSV-NDV vector is avirulent in 49 embryonated chicken eggs. Finally, systemic administration of rVSV-NDV in 50 orthotopic HCC-bearing immune-competent mice resulted in significant survival 51 prolongation. This strategy, therefore, combines the beneficial properties of the 52 rapidly replicating VSV platform with the highly efficient spread and immunogenic cell 53 death of a fusogenic virus, without risking the safety and environmental threats 54 associated with either parental vector. Taken together, rVSV-NDV represents an 55 attractive vector platform for clinical translation as a safe and effective oncolytic virus. 56