S.P. Cooper1, J. Mazar1, E. Sutton1, R. Rosario1, T. Westmoreland1 1Nemours Children Hospital, Biomedical Research, Orlando, FL, USA
Introduction: Despite excellent low-risk hepatoblastoma survival, the five-year overall survival for high-risk hepatoblastoma has not significantly improved despite intensive therapies. We propose the use of the oncolytic Zika virus as a therapy for children with high-risk hepatoblastoma. Our published work demonstrated a robust survival advantage for those mice hosting high-risk neuroblastoma and treated with direct Zika viral injection in a CD24-dependent manner. Based on these findings, we propose the utilization of Zika virus as an oncolytic therapy for high-risk hepatoblastoma.
Methods: Zika virus was applied to the cell line HUH-6, which was then examined for cell cytotoxicity in vitro. Data was collected daily for a five-day period using a fluorescence-based real-time detection assay for kinetic analysis of cell death. The results were subsequently correlated with examination by bright field microscopy. In addition, qRT-PCR was performed to determine CD24 expression in HUH-6 cells. CD24 siRNA was introduced to perform knockdown verification of Zika viral sensitivity in a CD24 dependent manner. HUH-6 cells were also introduced subcutaneously to 8-week-old NSG mice. The engrafted tumors were treated directly with increasing doses of Zika virus. Tissues were harvested and stained with H&E to determine any tumoricidal effect.
Results: qRT-PCR confirmed elevated CD24 expression in HUH-6 cells at an even higher level than sensitive neuroblastoma lines, indicating the possibility of susceptibility to Zika virus-mediated cell lysis. Significant increases in cell cytotoxicity as high as 95% were confirmed in HUH-6 cells treated with Zika virus in a time dependent manner that plateaued around 96 hours post infection. Bright field microscopy confirmed these findings with total cell lysis observed compared to uninfected cells which grew to confluency. Histological analysis of resected CDX tumor treated with Zika virus revealed extensive tumor lysis indicating a therapeutic effect.
Conclusion: Zika viral effectiveness in the treatment of human high-risk hepatoblastoma was demonstrated in cell culture and CDX mouse studies. HUH-6 cells’ CD24 expression was elevated and correlated with Zika viral cytotoxicity. As demonstrated in high-risk neuroblastomas, high-risk hepatoblastoma is effectively treated with Zika virus in a CD24 dependent manner. The results were further confirmed in a mouse model where the Zika viral treated tumor revealed significant tumor necrosis. These results indicate the potential viability of the use of Zika virus for the treatment of children with high-risk hepatoblastoma to improve their poor overall survival.