Development of Incurable Cancer Cell Targeted Agents Using Viral Technology

Abstract

  The safety and anti-tumor effect of oncolytic virus have been reported in a clinical study conducted in Japan. We have engineered a novel multimutated tumor-specific oncolytic herpes virus, harboring a smooth muscle-specific calponin promoter. Since tumor cells present in a hypoxic environment are known to be resistant to chemotherapy and radiotherapy, we also engineered a novel oncolytic herpes virus targeting a specific tumor microenvironment, which harbors a gene encoding a fusion protein of oxygen-dependent degradation (ODD) domain of HIF1α and ICP4, a master viral transcription factor required for replication. The recombinant virus selectively replicates in and disrupts the target tumor cells, including human sarcoma and malignant mesothelioma cells which are unresponsive to chemotherapy and molecular targeted therapy. We confirmed significant anti-tumor effects of the novel viruses in vivo in an allogeneic experimental model of an undifferentiated pleomorphic sarcoma (malignant fibrous histiocytoma; MFH) spontaneously generated in immunocompetent Fischer rats. Our viruses, manufactured in the Master Virus Seed Stock in the Good Manufacturing Practice facility will become novel agents that enable tumor cells unresponsive to conventional treatment to be disrupted.