Viral mimicry refers to the activation of innate antiviral immune responses due to the induction of endogenous retroelements (REs). Viral mimicry augments antitumor immune responses and sensitizes solid tumors to immunotherapy. Here, we found that targeting what we believe to be a novel, master epigenetic regulator, Zinc Finger Protein 638 (ZNF638), induces viral mimicry in glioblastoma (GBM) preclinical models and potentiates immune checkpoint inhibition (ICI). ZNF638 recruits the HUSH complex, which precipitates repressive H3K9me3 marks on endogenous REs. In GBM, ZNF638 is associated with marked locoregional immunosuppressive transcriptional signatures, reduced endogenous RE expression, and poor immune cell infiltration. Targeting ZNF638 decreased H3K9 trimethylation, increased REs, and activated intracellular dsRNA signaling cascades. Furthermore, ZNF638 knockdown upregulated antiviral immune programs and significantly increased PD-L1 immune checkpoint expression in diverse GBM models. Importantly, targeting ZNF638 sensitized mice to ICI in syngeneic murine orthotopic models through innate IFN signaling. This response was recapitulated in recurrent GBM (rGBM) samples with radiographic responses to checkpoint inhibition with widely increased expression of dsRNA, PD-L1, and perivascular CD8 cell infiltration, suggesting that dsRNA signaling may mediate response to immunotherapy. Finally, low ZNF638 expression was a biomarker of clinical response to ICI and improved survival in patients with rGBM and patients with melanoma. Our findings suggest that ZNF638 could serve as a target to potentiate immunotherapy in gliomas.

Glioblastoma (GBM) comprises 45.6% of all primary malignant brain cancers and is one of the most common and aggressive intracranial tumors in adults. Intratumoral heterogeneity with a wide range of proteomic, genetic, and epigenetic dysregulation contributes to treatment resistance and poor prognosis, thus demanding novel therapeutic approaches. To date, numerous clinical trials have been developed to target the proteome and epigenome of high-grade gliomas with promising results. However, studying RNA modifications, or RNA epitranscriptomics, is a new frontier within neuro-oncology. RNA epitranscriptomics was discovered in the 1970s, but in the last decade, the extent of modification of mRNA and various non-coding RNAs has emerged and been implicated in transposable element activation and many other oncogenic processes within the tumor microenvironment. This review provides background information and discusses the therapeutic potential of agents modulating epitranscriptomics in high-grade gliomas. A particular emphasis will be placed on how combination therapies that include immune agents targeting hERV-mediated viral mimicry could improve the treatment of GBM.

Outcomes for glioblastoma (GBM) remain poor despite standard-of-care treatments including surgical resection, radiation, and chemotherapy. Intratumoral heterogeneity contributes to treatment resistance and poor prognosis, thus demanding novel therapeutic approaches. Drug repositioning studies on antiretroviral therapy (ART) have shown promising potent antineoplastic effects in multiple cancers; however, its efficacy in GBM remains unclear. To better understand the pleiotropic anticancer effects of ART on GBM, we conducted a comprehensive drug repurposing analysis of ART in GBM to highlight its utility in translational neuro-oncology. To uncover the anticancer role of ART in GBM, we conducted a comprehensive bioinformatic and in vitro screen of antiretrovirals against glioblastoma. Using the DepMap repository and reversal of gene expression score, we conducted an unbiased screen of 16 antiretrovirals in 40 glioma cell lines to identify promising candidates for GBM drug repositioning. We utilized patient-derived neurospheres and glioma cell lines to assess neurosphere viability, proliferation, and stemness. Our in silico screen revealed that several ART drugs including reverse transcriptase inhibitors (RTIs) and protease inhibitors (PIs) demonstrated marked anti-glioma activity with the capability of reversing the GBM disease signature. RTIs effectively decreased cell viability, GBM stem cell markers, and proliferation. Our study provides mechanistic and functional insight into the utility of ART repurposing for malignant gliomas, which supports the current literature. Given their safety profile, preclinical efficacy, and neuropenetrance, ARTs may be a promising adjuvant treatment for GBM.

Background: Chimeric antigen receptor T-cell (CAR-T) therapy represents a promising frontier in oncology, but its application to high-grade gliomas (HGG) is challenged by the blood-brain barrier, limited efficacy, and significant toxicities associated with systemic administration. Locoregional delivery has the potential to address these shortcomings. This systematic review evaluates the safety and efficacy of locoregional vs systemic CAR-T cell delivery for HGG. Methods: Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a total of 112 studies were identified from three separate databases between 2015 and 2024. Of these, 19 articles were assessed for eligibility, resulting in 16 articles meeting the inclusion criteria with 194 treated patients across 14 clinical trials. A comparative meta-analysis was performed to compare the safety and efficacy outcomes of locoregional administration (eg, intracerebroventricular, intratumoral) with systemic (intravenous) delivery. Severe (grade ≥3) adverse event rates and therapeutic responses were pooled to calculate crude incidence, rate ratios, and relative risks (RRs) with 95% CIs. Both fixed-effect and random-effects models were used to evaluate incidence rate ratios. Results: Locoregional delivery was associated with a markedly improved safety profile, demonstrating an over 60% reduction in the incidence of grade ≥3 adverse events compared with systemic infusion (RR=0.39; 95% CI 0.30 to 0.52; p<0.001). Furthermore, locoregional strategies demonstrated encouraging signals of antitumor activity, including rates of disease responses not widely observed with systemic approaches (RR=3.79; 95% CI 1.23 to 11.70; p<0.05). Locoregional delivery also enables the analysis of cerebrospinal fluid to monitor T-cell trafficking and emerging biomarkers of immune activation. Conclusion: Intracranial delivery of CAR-T cells helps overcome key barriers that limit the efficacy and safety of systemic therapy in brain tumors. These findings support a paradigm shift that integrates locoregional delivery techniques as a pivotal component in the design of future CAR-T cell trials, offering a safer and potentially more effective therapeutic approach with greater opportunities for longitudinal sampling for patients with HGG.

Glioblastoma, the most aggressive primary brain tumor, carries a dismal prognosis, with median survival remaining under 15 months despite standard therapies. This is largely because of the tumor’s infiltrative nature, the restrictive blood–brain barrier, and intratumoral heterogeneity. Chlorotoxin (CTX), a 36-amino acid peptide derived from scorpion venom, has emerged as a promising multifunctional agent with high specificity for neuroectodermal tumors. In this comprehensive review, we highlight CTX’s potential to address critical limitations of current glioma treatments by bridging diagnostic and therapeutic modalities. Diagnostic advancements include CTX-conjugated near-IF fluorophores and nanoparticles for fluorescence-guided surgery and multimodal imaging to enhance intraoperative accuracy. On the therapeutic front, CTX enables targeted delivery of siRNA, radioisotopes, and novel immunotherapies such as CTX-directed chimeric antigen receptor T cells. We also examine emerging clinical data supporting the safety and preliminary efficacy of CTX-based interventions. Collectively, CTX represents a paradigm shift in neuro-oncology, offering a single molecule with both diagnostic and therapeutic capabilities. Its utility may also extend beyond gliomas to metastases and other malignancies within and beyond the central nervous system.