Going viral: targeting glioblastoma using oncolytic viruses

Glioblastoma (GBM) is a devastating malignant disease with a remarkably low 5-year survival rate and invariably poor prognosis. Current conventional treatment options (surgery, targeted radiotherapy, and a limited number of chemotherapies) are rarely entirely effective, leading to the majority of GBM patients experiencing disease recurrence shortly after primary treatment. Thus far, immunotherapeutic approaches towards GBM treatment have been largely unsuccessful due to the tumour site and profoundly immunosuppressive tumour microenvironment (TME). However oncolytic virus therapy (OVT) has been recently developed and licenced for the treatment of cancers and has the potential to switch the TME to become immune-reactive. This has been shown to both directly reduce tumour burden while also enhancing responsiveness to other therapies. In this review, we review the challenges faced by standard immunotherapies in GBM and outline the various approaches to OV treatment of GBM. We highlight the promise of OVT for targeting GBM by critically assessing the outcomes from recent clinical trials.