Oncolytic viruses as treatment for adult and pediatric high-grade gliomas: On the way to clinical success.

High-grade gliomas (HGGs) are the most common and aggressive primary brain tumors in both adult and pediatric populations. Despite the multimodal treatment modality currently available for HGG, the prognosis is dismal, with a low overall survival rate at two years after diagnosis. In the last decade, oncolytic virotherapy has emerged as a promising and feasible therapeutic tool in management of these tumors due to its oncolytic and immunostimulatory properties. Various oncolytic viruses, such as herpes simplex virus, adenovirus, poliovirus, reovirus, parvovirus and others, have been evaluated in the early stages of the clinical setting with regard to improving the outcome of patients with HGG. In this review, we summarize completed and ongoing clinical trials of oncolytic virotherapy for adult and pediatric malignant gliomas in terms of safety and efficacy, followed by a brief discussion about the current status and future directions of this therapy in the brain tumor field.