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Infectious bursal disease virus (IBDV) as a novel oncolytic virotherapy in glioblastoma.

BACKGROUND: Glioblastoma (GBM) is the most aggressive form of cancer of the central nervous system. Despite advances in immunotherapies and standard-of-care treatments for GBMs, clinical outcomes remain limited-owing to the immunosuppressive tumor microenvironment and the intrinsic resistance of GBM to conventional approaches. As a result, there is growing interest in rational combination strategies, particularly those pairing oncolytic viruses with immune-based therapies or established treatment modalities. Oncolytic viruses, by displaying conditionally enabled tumor cell-restricted replication, while stimulating antitumor immune responses and leaving healthy tissue unharmed, have the potential to reshape the therapeutic landscape in GBM and aid in achieving more durable benefits for patients. This study investigates the use of infectious bursal disease virus (IBDV) as a potential virotherapy for GBM. METHODS AND RESULTS: In vitro, IBDV infects and replicates within murine GBM cells and patient-derived GBM stem cells, inducing direct oncolysis and activating proinflammatory gene expression programs. IBDV also enhances the cytolytic activity of temozolomide (TMZ) in treated GBM cells, complementing TMZ chemotherapeutic activity. In vivo, treatment with IBDV in CT-2A GBM-bearing syngeneic mice significantly reduced tumor growth and improved survival compared with control mice. Intratumoral administration of IBDV induces a deep remodeling of the tumor immune microenvironment, reducing immunosuppressive M2-like macrophages and increasing the ratio of CD8+T cells to regulatory T cells. This reversion of immunosuppression linked to monocyte-derived macrophages has been confirmed on experimental ex vivo infections of explants derived from human GBM donors. CONCLUSION: These findings support further consideration of IBDV as a novel virotherapeutic agent for GBM.

Oncolytic Virotherapy

Oncolytic HSV-1-Mediated JAG1 Blockade Induces Glioma Senescence-Associated Secretory Phenotype to Increase Macrophage Activation and Cetuximab-Mediated Senolysis.

UNLABELLED: Oncolytic HSV-1 (oHSV) treatment induces Notch signaling and myelosuppression in the tumor microenvironment (TME) of preclinical cancer models. Clinically, the Notch ligand JAG1 was upregulated in patients with recurrent high-grade glioma treated with the oHSV CAN-3110 and correlated with poor prognosis. To better understand endogenous JAG1-mediated signaling in glioma cells and tumor-associated macrophages (TAM), we engineered a JAG1-antagonizing oHSV (OD-0J1) and interrogated its impact on cancer and myeloid cells in the TME. OD-0J1 antagonized JAG1-mediated Notch signaling and suppressed tumor growth in athymic nude and humanized mice, an effect reliant on Notch signaling in tumor cells. Kinome profiling revealed that OD-0J1 treatment suppressed CDK1, resulting in activation of the G2-M cell cycle checkpoint. Cell cycle arrest led to senescence and correlated with increased reactive oxygen species, p62, and autophagosome accumulation and senescence-associated β-galactosidase activity. OD-0J1-induced senescence resulted in increased production of inflammatory chemokines and damage-associated molecular patterns (DAMP), such as IL1β, HMGB1, and extracellular ATP. Coculturing macrophages with OD-0J1-infected tumor cells led to stimulation of chemotactic and proinflammatory pathways, as well as increased Fc receptor activation. Single-cell RNA sequencing and flow cytometric analysis of F4/80+ cells isolated from tumors showed a shift from tumor-supporting TAMs to inflammatory macrophages upon OD-0J1 treatment. Heightened EGFR activation in senescent cells was a mechanism to escape cell death, which created a unique opportunity for cetuximab as a senolytic agent. Combination therapy reduced EGFR signaling and induced macrophage-mediated antibody-dependent cellular cytotoxicity, thereby increasing the antitumor therapeutic efficacy of OD-0J1. SIGNIFICANCE: Leveraging JAG1 antagonism in the context of oncolytic virotherapy rewires macrophage polarization within the tumor microenvironment, which has wide implications for sensitizing tumors to antibodies, senolytic agents, and BiTE therapies.

Humans

An Evolutionary Framework Exploiting Virologs and Their Host Origins to Inform Poxvirus Protein Functions.

Poxviruses represent evolutionary successful infectious agents. As a family, poxviruses can infect a wide variety of species including humans, fish, and insects. While many other viruses are species-specific, an individual poxvirus species is often capable of infecting diverse hosts and cell types. For example, the prototypical poxvirus, vaccinia, is well known to infect numerous human cell types but can also infect cells from divergent hosts like frog neurons. Notably, poxvirus infections result in both detrimental human and animal diseases. The most infamous disease linked to a poxvirus is smallpox caused by variola virus. Poxviruses are large double-stranded DNA viruses, which uniquely replicate in the cytoplasm of cells. The model poxvirus genome encodes ~200 nonoverlapping protein-coding open reading frames (ORFs). Poxvirus gene products impact various biological processes like the production of virus particles, the host range of infectivity, and disease pathogenesis. In addition, poxviruses and their gene products have biomedical application with several species commonly engineered for use as vaccines and oncolytic virotherapy. Nevertheless, we still have an incomplete understanding of the functions associated with many poxvirus genes. In this chapter, we outline evolutionary insights that can complement ongoing studies of poxvirus gene functions and biology, which may serve to elucidate new molecular activities linked to this biomedically relevant class of viruses.

Animals

Targeting cancer stem cells predicts response and reverses chemoresistance in ascites-derived ovarian cancer organoids.

BACKGROUND: Ovarian cancer (OC) is frequently diagnosed at an advanced stage, where tumor heterogeneity and rapid development of chemoresistance contribute to a poor prognosis. The lack of reliable predictive biomarkers further hinders the development of effective treatment strategies. Patient-derived organoids (PDOs) have recently emerged as promising preclinical models with the potential to predict therapeutic responses. METHODS: OC PDOs were generated from ascites samples representing diverse histological subtypes. Histological and genomic fidelity to parental tumors was confirmed through histopathological analysis and whole-exome sequencing. Drug sensitivity to cisplatin and poly (ADP-ribose) polymerase (PARP) inhibitors was evaluated and correlated with 1-year clinical outcomes. We also investigated the therapeutic efficacy of oncolytic herpes simplex virus 2 (OH2) both as a single agent and in combination with cisplatin. The expression of cancer stem cell (CSC) markers CD44 and ALDH1A1 under treatment conditions was analyzed using immunohistochemistry and flow cytometry. RESULTS: PDOs were successfully established with an 86.2% success rate. These PDOs faithfully recapitulated the histopathological and genomic features of their corresponding tumors, maintaining intratumoral heterogeneity, and were amenable to xenotransplantation. Drug sensitivity assays demonstrated that PDOs accurately predicted patient-specific responses to cisplatin and PARP inhibitors. OH2 exhibited direct cytotoxicity in both cisplatin-sensitive and cisplatin-resistant PDOs, reducing cell viability by 20-60%. Notably, the combination treatment with OH2 and cisplatin enhanced antitumor efficacy, resulting in a significant reduction of the CD44+CSC subpopulation. CONCLUSIONS: Ascites-derived OC PDOs represent a robust platform for individualized drug testing. The combination of OH2 and cisplatin offers a novel and effective strategy for circumventing chemoresistance in OC.

Female

Syncytium-forming HSV-1 in cancer gene therapy: From molecular mechanisms to clinical translation.

Gene therapy has emerged as a promising strategy for cancer treatment, yet challenges in efficient gene delivery remain a major barrier. Herpes simplex virus type 1 (HSV-1), as an oncolytic virus, has garnered attention for its potential in cancer therapy due to its replicative capacity, large genomic payload, and relatively low toxicity. Notably, syncytium-forming HSV-1 (SF-HSV-1) not only exhibits enhanced and sustained antitumor efficacy but also triggers profound immune responses. However, the exact molecular mechanisms orchestrating HSV-1-induced syncytium formation, its resulting cytotoxicity, and its precise role in immune modulation remain incompletely understood. This review aims to provide an in-depth exploration of the mechanisms underlying HSV-1 syncytium formation and its therapeutic implications in cancer gene therapy.

Humans

Intratumor childhood vaccine-specific CD4+ T-cell recall coordinates antitumor CD8+ T cells and eosinophils.

BACKGROUND: Antitumor mechanisms of CD4+ T cells remain crudely defined, and means to effectively harness CD4+ T-cell help for cancer immunotherapy are lacking. Pre-existing memory CD4+ T cells hold potential to be leveraged for this purpose. Moreover, the role of pre-existing immunity in virotherapy, particularly recombinant poliovirus immunotherapy where childhood polio vaccine specific immunity is ubiquitous, remains unclear. Here we tested the hypothesis that childhood vaccine-specific memory T cells mediate antitumor immunotherapy and contribute to the antitumor efficacy of polio virotherapy. METHODS: The impact of polio immunization on polio virotherapy, and the antitumor effects of polio and tetanus recall were tested in syngeneic murine melanoma and breast cancer models. CD8+ T-cell and B-cell knockout, CD4+ T-cell depletion, CD4+ T-cell adoptive transfer, CD40L blockade, assessments of antitumor T-cell immunity, and eosinophil depletion defined antitumor mechanisms of recall antigens. Pan-cancer transcriptome data sets and polio virotherapy clinical trial correlates were used to assess the relevance of these findings in humans. RESULTS: Prior vaccination against poliovirus substantially bolstered the antitumor efficacy of polio virotherapy in mice, and intratumor recall of poliovirus or tetanus immunity delayed tumor growth. Intratumor recall antigens augmented antitumor T-cell function, caused marked tumor infiltration of type 2 innate lymphoid cells and eosinophils, and decreased proportions of regulatory T cells (Tregs). Antitumor effects of recall antigens were mediated by CD4+ T cells, limited by B cells, independent of CD40L, and dependent on eosinophils and CD8+ T cells. An inverse relationship between eosinophil and Treg signatures was observed across The Cancer Genome Atlas (TCGA) cancer types, and eosinophil depletion prevented Treg reductions after polio recall. Pretreatment polio neutralizing antibody titers were higher in patients living longer, and eosinophil levels increased in the majority of patients, after polio virotherapy. CONCLUSION: Pre-existing anti-polio immunity contributes to the antitumor efficacy of polio virotherapy. This work defines cancer immunotherapy potential of childhood vaccines, reveals their utility to engage CD4+ T-cell help for antitumor CD8+ T cells, and implicates eosinophils as antitumor effectors of CD4+ T cells.

Mice

Viral infection of cells within the tumor microenvironment mediates antitumor immunotherapy via selective TBK1-IRF3 signaling.

Activating intra-tumor innate immunity might enhance tumor immune surveillance. Virotherapy is proposed to achieve tumor cell killing, while indirectly activating innate immunity. Here, we report that recombinant poliovirus therapy primarily mediates antitumor immunotherapy via direct infection of non-malignant tumor microenvironment (TME) cells, independent of malignant cell lysis. Relative to other innate immune agonists, virotherapy provokes selective, TBK1-IRF3 driven innate inflammation that is associated with sustained type-I/III interferon (IFN) release. Despite priming equivalent antitumor T cell quantities, MDA5-orchestrated TBK1-IRF3 signaling, but not NFκB-polarized TLR activation, culminates in polyfunctional and Th1-differentiated antitumor T cell phenotypes. Recombinant type-I IFN increases tumor-localized T cell function, but does not mediate durable antitumor immunotherapy without concomitant pattern recognition receptor (PRR) signaling. Thus, virus-induced MDA5-TBK1-IRF3 signaling in the TME provides PRR-contextualized IFN responses that elicit functional antitumor T cell immunity. TBK1-IRF3 innate signal transduction stimulates eventual function and differentiation of tumor-infiltrating T cells.

Animals

Adenoviral Vectors in Gene Therapy: A Detailed Overview.

Adenoviral vectors (AdVs) represent one of the most extensively researched platforms in the realm of gene therapy, providing advantages such as high transduction efficiency, large transgene capacity, and broad tropism. This review provides a detailed and structured overview of AdVs, highlighting their biology, gene delivery mechanisms, clinical applications, and challenges limiting their broader therapeutic applicability. The study also explores recent progress in vector engineering, such as rare serotypes, capsid modifications, third-generation vectors, as well as strategies for immune modulation and toxicity reduction. AdVs are used in therapies for genetic disorders, oncology, and vaccinology, alongside innovations such as CRISPR-Cas9, nanotechnology, and artificial intelligence design. Nevertheless, persistent hurdles, including vector immunogenicity, hepatotoxicity, scalability, and the lack of durable expression, prevent widespread clinical use. This review consolidates current knowledge and presents a future perspective on how AdVs may evolve as powerful, adaptable, and precise tools in modern gene therapy. By contextualizing strengths and unresolved challenges, this work aims to give researchers and clinicians a balanced foundation for evaluating their future roles in translational medicine.

Humans

Development and preclinical evaluation of a decoy DLL4-encoding oncolytic HSV-1 for high-grade glioma.

Preclinical and clinical investigation of oncolytic HSV-1 (oHSV) treatment for cancer has indicated increased Notch signaling in tumors after treatment. Since Notch activation often heralds cancer cell stemness, angiogenesis, and invasion, the induction of this pathway after oHSV virotherapy can support tumor growth and limit response to virotherapy. Here, we evaluated the impact of blocking DLL4, a Notch ligand, on virotherapy. Matched tumor biopsies pre- and post-oHSV (CAN-3110, NCT03152318) treatment revealed an induction of DLL4 post-therapy. We observed that expression of a recombinant soluble decoy DLL4 (sDLL4) could block Notch activation in tumor cells. Thus, we engineered an oHSV vector designed to encode soluble DLL4 (OVsDLL4) to block ligand-mediated Notch signaling. RNA sequencing and gene set enrichment analysis revealed that, relative to control oHSV, OVsDLL4 blocked Notch and sprouting angiogenesis pathways after treatment. Despite slower virus replication in vitro, OVsDLL4 cytotoxicity remained effective against tumor cells. Transcriptome profiling also indicated a significant dysregulation of metabolic pathways related to oxidative phosphorylation and glutathione metabolism, in accordance with increased oxygen consumption observed by Seahorse analysis in cells expressing sDLL4. OVsDLL4-treated cells further showed increased reactive oxygen species relative to control oHSV-treated cells. Co-culture of infected tumor cells with immune cells revealed that OVsDLL4 treatment polarized them toward an inflammatory phenotype. In vivo, the therapeutic efficacy of OVsDLL4 was underscored, as treatment of glioma-bearing mice resulted in reduced tumor burden and prolonged survival.

Journal Article