Multi-modal Efficacy of a Chimeric Vesiculovirus Expressing the Morreton Glycoprotein in Sarcoma

Abstract

Vesiculoviruses are attractive oncolytic virus (OV) platforms due to their rapid replication, genome with appreciable transgene capacity, broad tropism, limited pre-existing immunity, and type I interferon response gradient between malignant and normal cells. We developed a synthetic chimeric virus (VMG) expressing the glycoprotein (G) from Morreton virus (MorV) with remaining genes from vesicular stomatitis virus (VSV). VMG exhibited in vitro efficacy in cell proliferation and cell death assays across a broad range of sarcoma subtypes and across multiple species. Notably, all cell lines tested showed ability of VMG to yield productive infections with rapid replication kinetics. Pilot safety evaluations of VMG in immunocompetent, non-tumor bearing mice showed absence of toxicity with intranasal doses as high as 1e10 TCID50. VMG resulted in tumor reduction in vivo in an immunodeficient subcutaneous Ewing sarcoma model at doses as low as 2e5 TCID50. In the immune competent murine syngeneic fibrosarcoma model, while no tumor inhibition was achieved with VMG, there was a robust induction of CD8+ T cells suggestive of potential for combination approaches with immunomodulatory agents such as immune checkpoint inhibitors. The studies described herein establish the potential for VMG as a novel oncolytic virotherapy platform with multi-modal anti-tumor effects in sarcoma.