While melanoma established the clinical foundation for oncolytic virus therapy, glioblastoma and central nervous system tumors represent a frontier of profound unmet need where the blood-brain barrier, immunologically privileged environment, and dismal prognosis create compelling rationale for viral approaches. Glioblastoma multiforme (GBM), the most common and aggressive primary brain tumor with median survival of 15 months despite standard therapy, is the leading neuro-oncology target for oncolytic viruses. The HSV-1 platform is particularly suited for GBM given its natural neurotropism, with genetically engineered deletion of neurovirulence factors (ICP34.5) enabling safe replication in tumor cells while sparing normal neurons. Over 12 oncolytic HSV trials for GBM were active in 2025, including DNAtrix's DNX-2401 (adenovirus) and Treovir's oHSV1 G207.

Direct intratumoral delivery via convection-enhanced delivery or injection into resected tumor cavities enables bypass of the blood-brain barrier and high local viral concentrations. Oncolytic Virus Therapy Market data indicates that Phase 1/2 trials demonstrated safety and preliminary efficacy signals, with some patients achieving durable responses exceeding 3 years. Over 680 GBM patients had received oncolytic virus therapy in clinical trials by 2025. The immune-privileged brain environment, while initially considered a barrier, may actually enhance oncolytic virus persistence and reduce systemic neutralizing antibody clearance.

Pediatric brain tumors including diffuse intrinsic pontine glioma (DIPG) and medulloblastoma represent additional high-need applications where conventional therapy options are limited and oncolytic viruses offer novel mechanisms. Measles virus derivatives, which naturally target the CD46 receptor highly expressed on glioma cells, have demonstrated preclinical promise and early clinical activity. Reovirus, which selectively replicates in Ras-activated tumor cells common in gliomas, has shown blood-brain barrier penetration and intratumoral accumulation after intravenous administration. The expanding neuro-oncology pipeline is supported by advanced neuroimaging techniques tracking viral distribution, biomarker studies of immune activation within the CNS, and innovative delivery technologies including implantable reservoirs and focused ultrasound blood-brain barrier opening. As delivery methods refine and combination approaches with radiation, temozolomide, and immunotherapy integrate, oncolytic virus therapy is transitioning from experimental neurosurgical adjunct to potentially transformative GBM treatment modality.

Q1: Why is HSV particularly suited for glioblastoma treatment? HSV-1's natural neurotropism and engineered deletion of neurovirulence factors (ICP34.5) enable safe tumor-selective replication; over 12 GBM trials were active in 2025 with 680+ patients treated.

Q2: How are oncolytic viruses delivered to brain tumors? Intratumoral injection and convection-enhanced delivery bypass the blood-brain barrier; measles virus and reovirus demonstrate potential for intravenous delivery with tumor-selective CNS accumulation.

Q3: What pediatric brain tumor applications are being investigated? DIPG and medulloblastoma are high-need targets where conventional options are limited; measles virus derivatives targeting CD46 and reovirus exploiting Ras activation show preclinical and early clinical promise.