J. Mazar1, J. K. Brooks1, M. Peloquin1, T. J. Westmoreland1 1Nemours Children’s Health System, Biomedical Research, Orlando, FL, USA
Introduction: Diffuse intrinsic pontine glioma (DIPG) is an aggressive tumor that forms from glial cells in the part of the brain stem called the pons and affects up to 300-400 children per year in the United States. Despite advances in DIPG biology, there remains no treatment that improves overall survival, and survival rates persist at less than 2% over 5 years. We propose to treat DIPG with the oncolytic Zika virus. We have previously shown that neuroblastoma cells and xenograft tumors are permissive to Zika viral infection. Because of the common heritage of DIPG and neuroblastoma, we propose that a Zika viral infection could be used as a putative therapy for patients with DIPG.
Methods: We utilized the immortalized DIPG cell line SF8628 and patient-derived cell lines SF11287, SF10423, and SF11653 to examine cell cytotoxicity after treatment with various concentrations of Zika virus. Data was collected every day for five days and measured using fluorescence-based real-time detection assays indicating both a kinetic analysis as well as an endpoint determination. In vitro cell survival was then directly correlated with examination by bright field microscopy. In addition, in vivo studies were performed in nude mice using SF8628 cells introduced subcutaneously, comparing Zika-infected tumors to vehicle.
Results: Following treatment with Zika virus, a significant increase in cell cytotoxicity was detected in all DIPG cells as early as 24 hours with all viral concentrations, which increased significantly in a time-dependent manner over the course of 5 days. Further examination by bright field microscopy corroborated >90% cell death using the highest concentration. In vivo studies revealed that introduction of Zika virus led to a loss of >90% of the tumor mass by Day 14 (compared to no loss of mass in vehicle-treated cells).
Conclusion: The in vitro efficacy of Zika virus as a treatment for human DIPG cells is comparable to results seen in prior experiments with neuroblastoma. In vivo experiments further corroborate these results, with the measurements indicating an average loss of >90% of the tumor mass over a period of 14 days in Zika-treated tumors compared to no loss of mass in the vehicle-treated controls. These results indicate that Zika virus could act as a putative therapy for the treatment of DIPG.