Oncolytic vesicular stomatitis virus for treatment of orthotopic hepatocellular carcinoma in immune-competent rats

Tumor-targeted replicating viruses are being developed as a novel class of oncolytic agents. Vesicular stomatitis virus (VSV) is a negative-strand RNA virus with inherent specificity for replication in tumor cells due to their attenuated antiviral responses. VSV as an oncolytic virus is particularly appealing for its exceptionally rapid replication rate in tumor cells, such that the oncolytic effects could be maximally manifested before the onset of potentially neutralizing antiviral immune responses in the host. To easily monitor VSV replication, we have rescued a recombinant VSV (rVSV) vector expressing the green fluorescent protein (GFP) gene (rVSV-GFP). Using this GFP-expressing virus, we have demonstrated the oncolytic potential of VSV against human and rat hepatocellular carcinoma (HCC). We found that rVSV-GFP replicated efficiently in cultured human and rat HCC cells, whereas normal human and rat hepatocytes were refractory. When a single dose of the vector was injected intratumorally into large orthotopically implanted HCC in immune-competent rats, rVSV-GFP effectively and selectively replicated throughout the solid tumor mass without apparent hepatotoxicity, caused tumor destruction, and inhibited tumor growth, which led to significant prolongation of animal survival. Our results show that VSV is an effective oncolytic agent against HCC in immune-competent hosts and warrants further development for future therapy in patients with HCC.