Humanized Murine Glioblastoma Models for Evaluation of Coxsackievirus Oncolytic Therapy

Background/Objectives: Glioblastoma remains the most lethal primary brain tumor in adults, and progress in oncolytic virotherapy is limited by the lack of immunocompetent models permissive to human-tropic viruses. Methods: Here, murine CT-2A and GL261 glioma and B16 melanoma cell lines were engineered to express human Coxsackievirus and Adenovirus Receptor (CXADR) fused to tagBFP, generating "humanized" tumors that preserve parental growth characteristics while acquiring high susceptibility to group B Coxsackieviruses (CVBs) and adenovirus serotype 5. Results: CXADR expression in CT-2A, GL261, and B16 cells markedly enhanced binding, internalization, and replication of CVBs in vitro, with the strongest effect observed for LEV14 (attenuated CVB5), which reached up to 10⁵-fold higher viral titers in humanized cells compared with parental cells. Unchanged sensitivity to vesicular stomatitis virus indicated receptor-specific effects. Humanized CT-2A-CXADR-BFP and GL261-CXADR-BFP cells initiated aggressive subcutaneous and intracranial tumors in syngeneic C57BL/6 mice without signs of immune rejection, and histology and MRI confirmed invasive high-grade glioma phenotypes. In intracranial CT-2A-CXADR-BFP tumors, repeated intratumoral LEV14 administration induced extensive tumor necrosis and prolonged survival despite the rapid development of neutralizing antibodies. Systemic intravenous LEV14 dosing produced strong oncolytic activity against subcutaneous CT-2A-CXADR-BFP tumors, as demonstrated by pronounced tumor growth inhibition, long-lasting regression in a subset of animals with gliomas, and improved overall survival. Conclusions: Collectively, these data establish CXADR-humanized models as versatile, immunocompetent platforms for evaluation of CXADR-dependent oncolytic enteroviruses.