137 - Zika Virus as an Oncolytic Treatment for Rhabdomyosarcoma

Publication Number: 2131.137

Lindsay Poulos, Nemours Children's Health, Orlando, FL, United States; Jeanne K. Brooks, Nemours Children's Hospital, Orlando, FL, United States; Simon P. Cooper, Nemours Children's Hospital, Orlando, FL, United States; Rosa Rosario, Nemours Children's Hospital, Orlando, FL, United States; Sabah Irfan, University of Central Florida, Windermere, FL, United States; Joseph Mazar, Nemours Children's Hospital, Davenport, FL, United States; Tamarah Westmoreland, Nemours Children's Hospital, Orlando, FL, United States; Amanda G. Lasseter, Nemours Children's Hospital, Orlando, FL, United States

Background: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. This aggressive cancer arises from skeletal muscle progenitor cells in areas such as the head and neck region, the extremities, and genitourinary tract. Despite current multimodal interventions including surgery, chemotherapy, and radiation, overall survival rates in advanced RMS remain low. We have previously shown that neuroblastoma is highly permissive to ZIKV infection. RMS and neuroblastoma both arise from nonterminally differentiated cells. Therefore, we propose that ZIKV infection could offer a targeted therapy for RMS.

Objective: To treat rhabdomyosarcoma tumors with the oncolytic Zika virus.

Design/Methods: We employed patient-derived, immortalized, embryonal and alveolar RMS cell lines RD and Rh30 to investigate cell cytotoxicity and proliferation post treatment with various MOIs of ZIKV. In conjunction, we treated cells with interferon-alpha (IFN-α) for 8 hours prior to infection with ZIKV at an MOI = 10. Data was collected every 12 hours for seven days and measured via fluorescence-based, real-time live-cell imaging.  In vitro cell survival was then correlated by bright field microscopy. In addition, RT-qPCR was performed to determine CD24 expression in RD and Rh30 cells.

Results: RT-qPCR revealed poor CD24 expression in both RD and Rh30 cell lines, similar to that seen in ZIKV resistant neuroblastoma SK-N-AS. Due to a lack of expression, this would predict that CD24 does not regulate viral sensitivity in RMS. Following ZIKV infection, both RMS cell lines exhibited a significant increase in cell cytotoxicity as early as 36 hours across all viral MOIs, with cell death progressively increasing in a time-dependent manner over five days. Brightfield microscopy further confirmed >95% cell death for all viral concentrations in both cell lines. Pre-treatment of IFN-α on RMS cells revealed a protective quality against viral lysis in a dose-dependent manner, suggesting a possible mechanism of defense against ZIKV infection.

Conclusion(s): The in vitro efficacy of ZIKV as a treatment for human RMS cells is both rapid and robust, yielding cell death results similar to those seen in our prior experiments with neuroblastoma. The pre-treatment of INF-α to ZIKV-treated RMS cell lines conferred protection against ZIKV-induced cell death, indicating a possible mechanism for its target host specificity. These results indicate that ZIKV could act as a potential novel therapy for RMS.