Since the US Food and Drug Administration first approved talimogene laherparepvec for the treatment of melanoma in 2015, the field of oncolytic immunotherapy (OI) has rapidly evolved. There are numerous ongoing clinical studies assessing the clinical activity of OIs across a wide range of tumor types. Further understanding of the mechanisms underlying the anti-tumor immune response has led to the development of OIs with improved immune-mediated preclinical efficacy. In this review, we discuss the key approaches for developing the next generation of herpes simplex virus-based OIs. Modifi- cations to the viral genome and incorporation of transgenes to promote safety, tumor-selective replication, and immune stimulation are reviewed. We also review the advantages and disadvantages of intratumoral versus intravenous administration, summarize clinical evidence supporting the use of OIs as a strategy to overcome resistance to immune checkpoint blockade, and consider emerging opportunities to improve OI efficacy in the combination setting.
CD33 and CD123 are expressed on the surface of human acute myeloid leukemia blasts and other noncancerous tissues such as hematopoietic stem cells. On-target off-tumor toxicities may limit chimeric antigen receptor T cell therapies that target both CD33 and CD123. To overcome this limitation, we developed bispecific human CD33/CD123 chimeric antigen receptor (CAR) T cells with an "AND" logic gate. We produced novel CD33 and CD123 scFvs from monoclonal antibodies that bound CD33 and CD123 and activated T cells. Screening of CD33 and CD123 CART cells for cytotoxicity, cytokine production, and proliferation was performed, and we selected scFvs for CD33/CD123 bispecific CARs. The bispecific CARs split 4-1BB co-stimulation on one scFv and CD3z on the other. In vitro testing of cytokine secretion and cytotoxicity resulted in selecting bispecific CAR 1 construct for in vivo analysis. The CD33/ CD123 bispecific CART cells were able to control acute myeloid leukemia (AML) in a xenograft AML mouse model similar to monospecific CD33 and CD123 CAR T cells while showing no on-target off-tumor effects. Based on our findings, human CD33/CD123 bispecific CAR T cells are a promising cell-based approach to prevent AML and support clinical investigation.
The use of oncolytic viruses (OVs) and adoptive cell therapies (ACT) have independently emerged as promising approaches for cancer immunotherapy. More recently, the combination of such agents to obtain a synergistic anticancer effect has gained attention, particularly in solid tumors, where im-mune-suppressive barriers of the microenvironment remain a challenge for desirable therapeutic efficacy. While adoptive cell monotherapies may be restricted by an immunologically cold or suppressive tumor microenvironment (TME), OVs can serve to prime the TME by eliciting a wave of cancer-spe-cific immunogenic cell death and inducing enhanced anti-tumor immunity. While OV/ACT synergy is an attractive approach, immune-suppressive barriers remain, and methods should be considered to optimize approaches for such combi-nation therapy. In this review, we summarize current ap-proaches that aim to overcome these barriers to enable optimal synergistic antitumor effects.
Mesothelin is a tumor-differentiation antigen discovered more than 30 years ago, although the development of novel and effective therapies targeting mesothelin still draws considerable interest in the oncology drug discovery and development field.1,2,3 In the December 19th issue of Molecular Therapy Oncolytics, a new study by Sun and colleagues reports the isolation and characterization of a novel human antibody heavy-chain variable (VH) domain named 3C9, targeting mesothelin as an antibody-drug conjugate (ADC).
Oncolytic viruses, modified for tumor-restricted infection, are a promising cancer immunotherapeutic, yet much remains to be understood about factors driving their activity and outcome in the tumor microenvironment. Here, we report that oncolytic herpes simplex virus C134, previously found to exert T celldependent efficacy in mouse models of glioblastoma, exerts T cell-independent efficacy in mouse models of medulloblastoma, indicating this oncolytic virus uses different mechanisms in different tumors. We investigated C134's behavior in mouse medulloblastomas, using single cell RNA sequencing to map C134-induced gene expression changes across cell types, timepoints, and medulloblastoma subgroup models at whole-transcriptome resolution. Our work details substantial oncolytic virus-induced transcriptional remodeling of medulloblastomainfiltrating immune cells, 10 subpopulations of monocytes and C134, and suggests C134 be investigated as a potential new therapy for medulloblastoma.
Ovarian cancer remains a challenging disease with limited treatment options, especially for the high-grade serous carcinoma (HGSC) subtype.1 In recent years, immunotherapy has emerged as a promising avenue for various cancer types. Despite the progress, its application in ovarian cancer has encountered obstacles that hinder its effectiveness. One of the key challenges is the immunologically "cold" nature of the tumor microenvironment.2 Ovarian tumors often exhibit a low number of infiltrating immune cells, making them less susceptible to immune-mediated destruction.
Epithelial ovarian cancer (EOC) remains one of the leading causes of cancer-related deaths among women worldwide. Receptor tyrosine kinases (RTKs) have long been sought as therapeutic targets for EOC, as they are frequently hyperactivated in primary tumors and drive disease relapse, progression, and metastasis. More recently, these oncogenic drivers have been implicated in EOC response to poly(ADP-ribose) polymerase (PARP) inhibitors and epigenomeinterfering agents. This evidence revives RTKs as promising targets for therapeutic intervention of EOC. This review summarizes recent studies on the role of RTKs in EOC malignancy and the use of their inhibitors for clinical treatment. Our focus is on the ERBB fam-ily, c-Met, and VEGFR, as they are linked to drug resistance and targetable using commercially available drugs. The importance of these RTKs and their inhibitors is highlighted by their impact on signal transduction and intratumoral heterogeneity in EOC and successful use as maintenance therapy in the clinic through suppression of the VEGF/VEGFR axis. Finally, the therapeutic potential of RTK inhibitors is discussed in the context of combinatorial targeting via co-inhibiting prolifera-tive and antiapoptotic pathways, epigenomic/transcriptional programs, and harnessing the efficacy of PARP inhibitors and programmed cell death 1/ligand 1 immune checkpoint therapies.
Adoptive cell therapy (ACT) is a highly promising approach to cancer treatment that is rapidly transforming the clinical landscape of oncology. Two main types of ACT are chimeric antigen receptor T cell (CAR-T) therapy and T cell receptor-modified T cell (TCR-T) therapy.1Johnson L.A. June C.H. Driving gene-engineered T cell immunotherapy of cancer.Cell Res. 2017; 27: 38-58https://doi.org/10.1038/cr.2016.154Crossref PubMed Scopus (209) Google Scholar While CAR-T is engineered to recognize cell surface antigens, TCR-T can target a broader spectrum of intracellular proteins that are processed and presented on human leukocyte antigens (HLAs). However, TCR binding is based on epitope recognition in the context of specific HLA alleles and there are over 36,000 unique alleles.2Barker D.J. Maccari G. Georgiou X. Cooper M.A. Flicek P. Robinson J. Marsh S.G.E. The IPD-IMGT/HLA Database.Nucleic Acids Res. 2023; 51: D1053-D1060https://doi.org/10.1093/nar/gkac1011Crossref PubMed Scopus (179) Google Scholar Only a small fraction of peptides and cognate TCRs from cancer-associated antigens (165 epitopes and 1,069 TCRs) have been reported in the Immune Epitope Database3Vita R. Mahajan S. Overton J.A. Dhanda S.K. Martini S. Cantrell J.R. Wheeler D.K. Sette A. Peters B. The Immune epitope Database (IEDB): 2018 update.Nucleic Acids Res. 2019; 47 (D339–d343)https://doi.org/10.1093/nar/gky1006Crossref PubMed Scopus (888) Google Scholar compared with all other antigens (1,695 epitopes and 170,395 TCRs). Further, the relationship between TCR affinity and quality of TCR signaling for optimal anticancer responses is also ambiguous.1Johnson L.A. June C.H. Driving gene-engineered T cell immunotherapy of cancer.Cell Res. 2017; 27: 38-58https://doi.org/10.1038/cr.2016.154Crossref PubMed Scopus (209) Google Scholar The major challenges in developing effective TCR-T immunotherapy for cancer include: (1) the identification of cancer-specific epitopes presented on HLA class I alleles, (2) the isolation of highly specific and potent TCRs, and (3) coverage of a large population across multiple HLA alleles. de Rooij et al.4de Rooij M.A.J. Remst D.F.G. van der Steen D.M. Wouters A.K. Hagedoorn R.S. Kester M.G.D. Meeuwsen M.H. Wachsmann T.L.A. de Ru A.H. van Veelen P.A. et al.A library of cancer testis specific T cell receptors for T cell receptor gene therapy.Mol. Ther. Oncolytics. 2023; 28: 1-14https://doi.org/10.1016/j.omto.2022.11.007Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar report systematic studies to expand the repertoire of TCRs targeting melanoma-associated antigen (MAGE) proteins for cancer therapy. The MAGE gene family was initially described as a group of cancer-testis antigens5Simpson A.J.G. Caballero O.L. Jungbluth A. Chen Y.T. Old L.J. Cancer/testis antigens, gametogenesis and cancer.Nat. Rev. Cancer. 2005; 5: 615-625https://doi.org/10.1038/nrc1669Crossref PubMed Scopus (1304) Google Scholar with restricted expression in germ cells, placenta, and tumor cells. Several MAGE-targeted TCR-T therapies have advanced to clinical trials, but previously reported neurological and cardiovascular toxicities6Morgan R.A. Chinnasamy N. Abate-Daga D. Gros A. Robbins P.F. Zheng Z. Dudley M.E. Feldman S.A. Yang J.C. Sherry R.M. et al.Cancer regression and neurological toxicity following anti-MAGE-A3 TCR gene therapy.J. Immunother. 2013; 36: 133-151https://doi.org/10.1097/CJI.0b013e3182829903Crossref PubMed Scopus (861) Google Scholar,7Linette G.P. Stadtmauer E.A. Maus M.V. Rapoport A.P. Levine B.L. Emery L. Litzky L. Bagg A. Carreno B.M. Cimino P.J. et al.Cardiovascular toxicity and titin cross-reactivity of affinity-enhanced T cells in myeloma and melanoma.Blood. 2013; 122: 863-871https://doi.org/10.1182/blood-2013-03-490565Crossref PubMed Scopus (825) Google Scholar due to TCR cross-reactivities have raised significant caution. To address this issue, the authors constructed a bioinformatics platform to pre-screen candidate MAGE genes wherein they filtered antigens expressed in benign organs other than the testis and placenta. Only MAGE peptides that share limited similarity with other human proteins were selected. They then applied a multipronged approach to identify epitopes from these candidate MAGE proteins on multiple high-frequency HLA class I alleles using both an in silico predictive algorithm and liquid chromatography-mass spectrometry-based immunopeptidomic profiling. This large repertoire of HLA class I alleles covers a vast swath of the ethnic groups represented in the global population. This tour de force approach yielded 38 peptides for potential downstream TCR isolation, greatly expanding the range of established MAGE epitopes for immunotherapeutic development. T cells bearing high-affinity TCRs targeting MAGE may be extremely rare in peripheral blood mononuclear cells from healthy donors as they may be negatively selected during thymic education.8Klein L. Kyewski B. Allen P.M. Hogquist K.A. Positive and negative selection of the T cell repertoire: what thymocytes see (and don't see).Nat. Rev. Immunol. 2014; 14: 377-391https://doi.org/10.1038/nri3667Crossref PubMed Scopus (863) Google Scholar To overcome this, the authors utilized an allogeneic HLA repertoire from 54 healthy donors as HLA mismatch could be leveraged to identify T cells with high-affinity MAGE TCRs using peptide-HLA class I tetramers. Interestingly, the cross-reactivities of TCRs reported all involved other MAGE proteins, likely due to high sequence homology. Another possibility is that TCRs may recognize structurally similar peptide-HLA class I complexes despite differences in peptide sequences. While the efforts by the authors to test a panel of MAGE-negative cell lines is commendable, tractable methods to effectively define a TCR's specificity and predict off-target binding and activation remain elusive in the field. The use of high-throughput libraries with large peptide diversity combined with yeast surface display may facilitate this process.9Birnbaum M.E. Mendoza J.L. Sethi D.K. Dong S. Glanville J. Dobbins J. Ozkan E. Davis M.M. Wucherpfennig K.W. Garcia K.C. Deconstructing the peptide-MHC specificity of T cell recognition.Cell. 2014; 157: 1073-1087https://doi.org/10.1016/j.cell.2014.03.047Abstract Full Text Full Text PDF PubMed Scopus (384) Google Scholar Seven MAGE-specific TCRs described in this study demonstrated in vitro anticancer activity and three showed near-complete tumor eradication in vivo indicating significant promise for future clinical translation. Most importantly, the work establishes a foundation for further epitope discovery and the isolation/nomination of TCRs for broad application in TCR gene therapy for cancer. The authors have intellectual property interests related to T cell immunotherapies.
VG2025 is a recombinant oncolytic herpes simplex virus type 1 (HSV-1) that uses transcriptional and translational dual regulation (TTDR) of critical viral genes to enhance virus safety and promote tumor-specific virus replication without reducing virulence. The TTDR platform is based on transcriptional control of the essential HSV-1 immediate-early protein ICP27 using a tumor-specific carcinoembryonic antigen (CEA) promoter, coupled with translational control of the neurovirulence factor ICP34.5 using multiple microRNA (miR)-binding sites. VG2025 further incorporates IL-12 and the IL-15/IL-15 receptor alpha subunit complex to enhance the antitumor and immune stimulatory properties of oncolytic HSVs. The TTDR strategy was verified in vitro and shown to be highly selective. Strong in vivo antitumor efficacy was observed following both intratumoral and intravenous administration. Clear abscopal and immune memory effects were also evident, indicating a robust antitumor immune response. Gene expression profiling of treated tumors revealed increased immune cell infiltration and activation of multiple immune-signaling pathways when compared with the backbone virus. Absence of neurotoxicity was verified in mice and in rhesus monkeys. Taken together, the enhanced tumor clearance, excellent safety profile, and positive correlation between CEA levels and viral replication efficiency may provide an opportunity for using biomarker-based precision medicine in oncolytic virotherapy.
Colorectal Cancer (CRC) is the second leading cause of cancer-related death in the United States. Most CRC patients present with a microsatellite stable (MSS) phenotype and are highly resistant to immunotherapies. Tumor extracellular vesicles (TEVs), secreted by tumor cells, can contribute to intrinsic resistance to immunotherapy in CRC. We previously showed that autologous TEVs without functional miR-424 induce anti-tumor immune responses. We hypothesized that allogeneic modified CRC-TEVs without miR-424 (mouse homolog miR-322) derived from an MC38 background would effectively stimulate CD8+ T cell response and limit CT26 tumor growth. Here we show that prophylactic administration of MC38 TEVs without functional miR-424 significantly increased CD8+ T cells in CT26 CRC tumors and limited tumor growth, not B16-F10 melanoma tumors. We further show that the depletion of CD4+ and CD8+ T cells abolished the protective effects of MC38 TEVs without functional miR-424. We further show that TEVs can be taken up by DCs in vitro, and subsequent prophylactic administration of autologous DCs exposed to MC38 TEVs without functional miR-424 suppressed tumor growth and increased CD8+ T cells compared to MC38 wild-type TEVs exposed to DCs, in Balb/c mice bearing CT26 tumors. Notably, the modified EVs were well tolerated and did not increase cytokine expression in peripheral blood. These findings suggest that allogeneic-modified CRC-EVs without immune suppressive miR-424 can induce antitumor CD8+ T cell responses and limit tumor growth in vivo.
DNA alkylating drugs have been used as cancer chemotherapy with variable outcomes. The establishment of predictive biomarkers to identify patients who will effectively respond to treatment would allow for the development of personalized therapies. As the degree of interaction of alkylating drug with DNA plays a key role in their mechanism of action, our hypothesis is that the measurement of the DNA adducts formed by alkylating drugs could be used to inform patient stratification. Beginning with busulfan, we took advantage of our DNA adductomic approach to characterize DNA adducts formed by reacting busulfan with calf-thymus DNA. Samples collected from six patients undergoing busulfan-based chemotherapy prior to allogeneic hematopoietic cell transplantation were analyzed for the presence of busulfan-derived DNA adducts. Among the 15 adducts detected in vitro, 12 were observed in the patient blood confirming the presence of a large profile of DNA adducts in vivo. Two of the detected adducts were structurally confirmed by comparison with synthetic standards and quantified in patients. These data confirm our ability to comprehensively characterize busulfan-derived DNA damage and set the stage for the development of methods to support personalized chemotherapy.
Aerobic glycolysis is a hallmark property of cancer metabolism. Enolase is a glycolytic enzyme that catalyzes the conversion of 2-phosphoglycerate into phosphoenolpyruvate. In mammals, enolases exist in three isoforms, encoded by the genes ENO1, ENO2, and ENO3. The altered expression of enolases is a common occurrence in various types of cancer. Although most published studies on enolases have predominantly focused on the role of ENO1 in cancer, ENO2 and ENO3 have recently emerged as crucial regulatory molecules in cancer development. Significant progress has been made in understanding their multifaceted roles in oncogenesis. In this comprehensive review, we provide an overview of the structure, subcellular localization, diagnostic and prognostic significance, biological functions, and molecular mechanisms of ENO2 and ENO3 in cancer progression. The importance of enolase in cancer development makes it a novel therapeutic target for clinical applications. Furthermore, we discuss anticancer agents designed to target enolases and summarize their anticancer efficacy in both in vitro and in vivo studies.
Multiple clinical trials exploring the potential of adoptive natural killer (NK) cell therapy for cancer have employed ex vivo expansion using feeder cells to obtain large numbers of NK cells. We have previously utilized the rhesus macaque model to clonally track the NK cell progeny of barcode-transduced CD34+ stem and progenitor cells after transplant. In this study, NK cells from barcoded rhesus macaques were used to study the changes in NK cell clonal patterns that occurred during ex vivo expansion using culture protocols similar to those employed in clinical preparation of human NK cells including irradiated lymphoblastoid cell line (LCL) feeder cells or K562 cells expressing 4-1BBL and membrane-bound interleukin-21 (IL-21). NK expansion cultures resulted in the proliferation of clonally diverse NK cells, which, at day 14 harvest, contained greater than 50% of the starting barcode repertoire. Diversity as measured by Shannon index was maintained after culture. With both LCL and K562 feeders, proliferation of long-lived putative memory-like NK cell clones was observed, with these clones continuing to constitute a mean of 31% of the total repertoire of expanded cells. These experiments provide insight into the clonal makeup of expanded NK cell clinical products.
Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease known for its dense tumor stroma. Focal adhesion kinase inhibitor (FAKi), a non-receptor type tyrosine kinase inhibitor, reduces the tumor stroma. G47Δ, a third-generation oncolytic herpes simplex virus type 1, destroys tumor cells selectively and induces antitumor immune responses. This study evaluates the efficacy of FAKi and G47Δ in PDAC models in combination with or without immune checkpoint inhibitors. G47Δ was effective in human PDAC cell lines in vitro and in subcutaneous as well as orthotopic tumor models. Transgenic mouse-derived #146 cells were used to generate subcutaneous PDAC tumors with rich stroma in immunocompetent mice. In this #146 tumor model, the efficacy of FAKi was synergistically augmented when combined with G47Δ, which reflected not only a decreased stromal content but also a significant shifting of the tumor microenvironment toward immune stimulation. In transgenic autochthonous PKF mice, a rare model that develops stroma-rich PDAC with a 100% penetrance and resembles human PDAC in various aspects, the prolongation of survival compared with FAKi alone was achieved only when FAKi was combined with G47Δ and immune checkpoint inhibitors. The FAKi combination therapy may be useful to overcome the treatment resistance of stroma-rich PDAC.
Glioblastoma multiforme (GBM) is among the most difficult cancers to treat with a 5-year survival rate less than 5%. An immunotherapeutic vaccine approach targeting GBM-specific antigen, EGFRvIII, previously demonstrated important clinical impact. However, immune escape variants were reported in the trial, suggesting that multivalent approaches targeting GBM-associated antigens may be of importance. Here we focused on multivalent in vivo delivery of synthetic DNA-encoded bispecific T cell engagers (DBTEs) targeting two GBM-associated antigens, EGFRvIII and HER2. We designed and optimized an EGFRvIII-DBTE that induced T cell-mediated cytotoxicity against EGFRvIII-expressing tumor cells. In vivo delivery in a single administration of EGFRvIII-DBTE resulted in durable expression over several months in NSG mice and potent tumor control and clearance in both peripheral and orthotopic animal models of GBM. Next, we combined delivery of EGFRvIII-DBTEs with an HER2-targeting DBTE to treat heterogeneous GBM tumors. In vivo delivery of dual DBTEs targeting these two GBM-associated antigens exhibited enhanced tumor control and clearance in a heterogeneous orthotopic GBM challenge, while treatment with single-target DBTE ultimately allowed for tumor escape. These studies support that combined delivery of DBTEs, targeting both EGFRvIII and HER2, can potentially improve outcomes of GBM immunotherapy, and such multivalent approaches deserve additional study.
Primary drug resistance and minimal residual disease are major challenges in the treatment of B cell neoplasms. Therefore, this study aimed to identify a novel treatment capable of eradicating malignant B cells and drug-resistant disease. Oncolytic viruses eradicate malignant cells by direct oncolysis and activation of anti-tumor immunity, have proven anti-cancer efficacy, and are safe and well tolerated in clinical use. Here, we demonstrate that the oncolytic virus coxsackievirus A21 can kill a range of B cell neoplasms, irrespective of an anti-viral interferon response. Moreover, CVA21 retained its capacity to kill drug-resistant B cell neoplasms, where drug resistance was induced by co-culture with tumor microenvironment support. In some cases, CVA21 efficacy was actually enhanced, in accordance with increased expression of the viral entry receptor ICAM-1. Importantly, the data confirmed preferential killing of malignant B cells and CVA21 dependence on oncogenic B cell signaling pathways. Significantly, CVA21 also activated natural killer (NK) cells to kill neoplastic B cells and drug-resistant B cells remained susceptible to NK cell-mediated lysis. Overall, these data reveal a dual mode of action of CVA21 against drug-resistant B cells and support the development of CVA21 for the treatment of B cell neoplasms.
Vesiculoviruses are attractive oncolytic virus platforms due to their rapid replication, appreciable transgene capacity, broad tropism, limited preexisting immunity, and tumor selectivity through type I interferon response defects in malignant cells. We developed a synthetic chimeric virus (VMG) expressing the glycoprotein (G) from Morreton virus (MorV) and utilizing the remaining structural genes from vesicular stomatitis virus (VSV). VMG exhibited in vitro efficacy by inducing oncolysis in a broad range of sarcoma subtypes across multiple species. Notably, all cell lines tested showed the ability of VMG to yield productive infection with rapid replication kinetics and induction of apoptosis. Furthermore, pilot safety evaluations of VMG in immunocompetent, non-tumor-bearing mice showed an absence of toxicity with intranasal doses as high as 1e10 50% tissue culture infectious dose (TCID50)/kg. Locoregional administration of VMG in vivo resulted in tumor reduction in an immunodeficient Ewing sarcoma xenograft at doses as low as 2e5 TCID50. In a murine syngeneic fibrosarcoma model, while no tumor inhibition was achieved with VMG, there was a robust induction of CD8+ T cells within the tumor. The studies described herein establish the promising potential for VMG to be used as a novel oncolytic virotherapy platform with anticancer effects in sarcoma.
Wild-type reovirus serotype 3 Dearing (T3wt), a non-patho-genic intestinal virus, has shown promise as a cancer therapy in clinical trials, but it would benefit from an increased po-tency. Given that T3wt is naturally adapted to the intestinal environment (rather than tumors), we genetically modified reovirus to improve its infectivity in cancer cells. Various reovirus mutants were created, and their oncolytic potency was evaluated in vitro using plaque size as a measure of virus fitness in cancer cells. Notably, Super Virus 5 (SV5), carrying five oncolytic mutations, displayed the largest plaques in breast cancer cells among the mutants tested, indicating the potential for enhancing oncolytic potency through the combination of mutations. Furthermore, in a HER2+ murine breast cancer model, mice treated with SV5 exhibited superior tumor reduc-tion and increased survival compared with those treated with PBS or T3wt. Intriguingly, SV5 did not replicate faster than T3wt in cultured cells but demonstrated a farther spread rela-tive to T3wt, attributed to its reduced attachment to cancer cells. These findings highlight the significance of increased vi-rus spread as a crucial mechanism for improving oncolytic vi-rus activity. Thus, genetic modifications of reovirus hold the potential for augmenting its efficacy in cancer therapy.
Longstanding evidence implicate glioma stem-like cells as the main drivers contributing toward glioblastoma (GBM) therapy resistance and tumor recurrence. Although oncolytic herpes simplex virus (oHSV) viral therapy is a promising biological therapy recently approved for melanoma (in the United States and Europe) and GBM (in Japan); however, the impact of this therapy on GBM stem-like cells (GSCs) is understudied. Here we show that post-oHSV virotherapy activated AKT signaling results in an enrichment of GSC signatures in glioma, which mimics the enrichment in GSC observed after radiation treatment. We also uncovered that a second-generation oncolytic virus armed with PTEN-L (oHSV-P10) decreases this by moderating IL6/JAK/STAT3 signaling. This ability was retained in the presence of radiation treatment and oHSV-P10-sensitized intracranial GBM to radiotherapy. Collectively, our findings uncover potential mechanisms to overcome GSC-mediated radiation resistance via oHSV-P10.
