Targeting NKG2D ligands in glioblastoma with a bispecific T-cell engager is augmented with conventional therapy and enhances oncolytic virotherapy of glioma stem-like cells.

BACKGROUND: Glioblastoma (GBM) almost invariably becomes resistant towards conventional treatment of radiotherapy and temozolomide (TMZ) chemotherapy, partly due to subpopulations of intrinsically resistant glioma stem-like cells (GSC). The oncolytic herpes simplex virus-1 G207 is a promising approach for GBM virotherapy although its efficacy in patients with GBM is often limited. Natural killer group 2 member D ligands (NKG2DLs) are minimally expressed by healthy cells but are upregulated by the DNA damage response (DDR) and in malignant cells with chronic DDR signaling, resulting in innate immune activation. METHODS: We have designed a bispecific T-cell engager (BiTE) capable of cross-linking CD3 on T cells with NKG2DL-expressing GBM cells. We then engineered the G207 virus to express the NKG2D BiTE and secrete it from infected cells. The efficacy of the free BiTE and BiTE delivered by G207 was evaluated in combination with conventional therapies in GBM cells and against patient-derived GSCs in the context of T-cell activation and target cell viability. RESULTS: NKG2D BiTE-mediated cross-linking of GBM cells and T cells causes antigen-independent T-cell activation, pro-inflammatory cytokine release, and tumor cell death, thereby combining direct viral oncolysis with BiTE-mediated cytotoxicity. Surface NKG2DL expression was further elevated on GBM cells following pretreatment with sublethal doses of TMZ and radiation to induce the DDR, increasing sensitivity towards G207-NKG2D BiTE and achieving synergistic cytotoxicity. We also demonstrate a novel strategy for targeting GSCs that are non-permissive to G207 infection but remain sensitive to NKG2D BiTE. CONCLUSIONS: We propose a potential model for targeting GSCs in heterogeneous tumors, whereby differentiated GBM cells infected with G207-NKG2D BiTE produce NKG2D BiTE locally, directing T-cell cytotoxicity towards the GSC subpopulations in the tumor microenvironment.

Preliminary efficacy and safety of YSCH-01 in patients with advanced solid tumors: an investigator-initiated trial.

OBJECTIVE: To evaluate the safety and preliminary efficacy of YSCH-01 (Recombinant L-IFN adenovirus) in subjects with advanced solid tumors. METHODS: In this single-center, open-label, investigator-initiated trial of YSCH-01, 14 patients with advanced solid tumors were enrolled. The study consisted of two distinct phases: (1) the dose escalation phase and (2) the dose expansion phase; with three dose groups in the dose escalation phase based on dose levels (5.0×109 viral particles (VP)/subject, 5.0×1010 VP/subject, and 5.0×1011 VP/subject). Subjects were administered YSCH-01 injection via intratumoral injections. The safety was assessed using National Cancer Institute Common Terminology Criteria for Adverse Events V.5.0, and the efficacy evaluation was performed using Response Evaluation Criteria in Solid Tumor V.1.1. RESULTS: 14 subjects were enrolled in the study, including 9 subjects in the dose escalation phase and 5 subjects in the dose expansion phase. Of the 13 subjects included in the full analysis set, 4 (30.8%) were men and 9 (69.2%) were women. The most common tumor type was lung cancer (38.5%, 5 subjects), followed by breast cancer (23.1%, 3 subjects) and melanoma (23.1%, 3 subjects). During the dose escalation phase, no subject experienced dose-limiting toxicities. The content of recombinant L-IFN adenovirus genome and recombinant L-IFN protein in blood showed no trend of significant intergroup changes. No significant change was observed in interleukin-6 and interferon-gamma. For 11 subjects evaluated for efficacy, the overall response rate with its 95% CI was 27.3% (6.02% to 60.97%) and the disease control rate with its 95% CI was 81.8% (48.22% to 97.72%). The median progression-free survival was 4.97 months, and the median overall survival was 8.62 months. In addition, a tendency of decrease in the sum of the diameters of target lesions was observed. For 13 subjects evaluated for safety, the overall incidence of adverse events (AEs) was 92.3%, the overall incidence of adverse drug reactions (ADRs) was 84.6%, and the overall incidence of >Grade 3 AEs was 7.7%, while no AEs/ADRs leading to death occurred. The most common AEs were fever (69.2%), nausea (30.8%), vomiting (30.8%), and hypophagia (23.1%). CONCLUSIONS: The study shows that YSCH-01 injections were safe and well tolerated and exhibited preliminary efficacy in patients with advanced solid tumors, supporting further investigation to evaluate its efficacy and safety. TRIAL REGISTRATION NUMBER: NCT05180851.

m1A inhibition fuels oncolytic virus-elicited antitumor immunity via downregulating MYC/PD-L1 signaling.

N1-methyladenosine (m1A) RNA methylation is critical for regulating mRNA translation; however, its role in the development, progression, and immunotherapy response of head and neck squamous cell carcinoma (HNSCC) remains largely unknown. Using Tgfbr1 and Pten conditional knockout (2cKO) mice, we found the neoplastic transformation of oral mucosa was accompanied by increased m1A modification levels. Analysis of m1A-associated genes identified TRMT61A as a key m1A writer linked to cancer progression and poor prognosis. Mechanistically, TRMT61A-mediated tRNA-m1A modification promotes MYC protein synthesis, upregulating programmed death-ligand 1 (PD-L1) expression. Moreover, m1A modification levels were also elevated in tumors treated with oncolytic herpes simplex virus (oHSV), contributing to reactive PD-L1 upregulation. Therapeutic m1A inhibition sustained oHSV-induced antitumor immunity and reduced tumor growth, representing a promising strategy to alleviate resistance. These findings indicate that m1A inhibition can prevent immune escape after oHSV therapy by reducing PD-L1 expression, providing a mutually reinforcing combination immunotherapy approach.

Molecular Circuits of Immune Sensing and Response to Oncolytic Virotherapy.

Oncolytic virotherapy is a promising immunotherapy approach for cancer treatment that utilizes viruses to preferentially infect and eliminate cancer cells while stimulating the immune response. In this review, we synthesize the current literature on the molecular circuits of immune sensing and response to oncolytic virotherapy, focusing on viral DNA or RNA sensing by infected cells, cytokine and danger-associated-signal sensing by neighboring cells, and the subsequent downstream activation of immune pathways. These sequential sense-and-response mechanisms involve the triggering of molecular sensors by viruses or infected cells to activate transcription factors and related genes for a breadth of immune responses. We describe how the molecular signals induced in the tumor upon virotherapy can trigger diverse immune signaling pathways, activating both antigen-presenting-cell-based innate and T cell-based adaptive immune responses. Insights into these complex mechanisms provide valuable knowledge for enhancing oncolytic virotherapy strategies.

Patient-derived tumoroids and proteomic signatures: tools for early drug discovery.

Onco-virotherapy is an emergent treatment for cancer based on viral vectors. The therapeutic activity is based on two different mechanisms including tumor-specific oncolysis and immunostimulatory properties. In this study, we evaluated onco-virotherapy in vitro responses on immunocompetent non-small cell lung cancer (NSCLC) patient-derived tumoroids (PDTs) and healthy organoids. PDTs are accurate tools to predict patient's clinical responses at the in vitro stage. We showed that onco-virotherapy could exert specific antitumoral effects by producing a higher number of viral particles in PDTs than in healthy organoids. In the present work, we used multiplex protein screening, based on proximity extension assay to highlight different response profiles. Our results pointed to the increase of proteins implied in T cell activation, such as IFN-γ following onco-virotherapy treatment. Based on our observation, oncolytic viruses-based therapy responders are dependent on several factors: a high PD-L1 expression, which is a biomarker of greater immune response under immunotherapies, and the number of viral particles present in tumor tissue, which is dependent to the metabolic state of tumoral cells. Herein, we highlight the use of PDTs as an alternative in vitro model to assess patient-specific responses to onco-virotherapy at the early stage of the preclinical phases.

Fn-OMV potentiates ZBP1-mediated PANoptosis triggered by oncolytic HSV-1 to fuel antitumor immunity.

Oncolytic viruses (OVs) show promise as a cancer treatment by selectively replicating in tumor cells and promoting antitumor immunity. However, the current immunogenicity induced by OVs for tumor treatment is relatively weak, necessitating a thorough investigation of the mechanisms underlying its induction of antitumor immunity. Here, we show that HSV-1-based OVs (oHSVs) trigger ZBP1-mediated PANoptosis (a unique innate immune inflammatory cell death modality), resulting in augmented antitumor immune effects. Mechanistically, oHSV enhances the expression of interferon-stimulated genes, leading to the accumulation of endogenous Z-RNA and subsequent activation of ZBP1. To further enhance the antitumor potential of oHSV, we conduct a screening and identify Fusobacterium nucleatum outer membrane vesicle (Fn-OMV) that can increase the expression of PANoptosis execution proteins. The combination of Fn-OMV and oHSV demonstrates potent antitumor immunogenicity. Taken together, our study provides a deeper understanding of oHSV-induced antitumor immunity, and demonstrates a promising strategy that combines oHSV with Fn-OMV.

Combination therapy with oncolytic virus and T cells or mRNA vaccine amplifies antitumor effects.

Antitumor therapies based on adoptively transferred T cells or oncolytic viruses have made significant progress in recent years, but the limited efficiency of their infiltration into solid tumors makes it difficult to achieve desired antitumor effects when used alone. In this study, an oncolytic virus (rVSV-LCMVG) that is not prone to induce virus-neutralizing antibodies was designed and combined with adoptively transferred T cells. By transforming the immunosuppressive tumor microenvironment into an immunosensitive one, in B16 tumor-bearing mice, combination therapy showed superior antitumor effects than monotherapy. This occurred whether the OV was administered intratumorally or intravenously. Combination therapy significantly increased cytokine and chemokine levels within tumors and recruited CD8+ T cells to the TME to trigger antitumor immune responses. Pretreatment with adoptively transferred T cells and subsequent oncolytic virotherapy sensitizes refractory tumors by boosting T-cell recruitment, down-regulating the expression of PD-1, and restoring effector T-cell function. To offer a combination therapy with greater translational value, mRNA vaccines were introduced to induce tumor-specific T cells instead of adoptively transferred T cells. The combination of OVs and mRNA vaccine also displays a significant reduction in tumor burden and prolonged survival. This study proposed a rational combination therapy of OVs with adoptive T-cell transfer or mRNA vaccines encoding tumor-associated antigens, in terms of synergistic efficacy and mechanism.

OV Modulators of the Paediatric Brain TIME: Current Status, Combination Strategies, Limitations and Future Directions.

Oncolytic viruses (OVs) are characterised by their preference for infecting and replicating in tumour cells either naturally or after genetic modification, resulting in oncolysis. Furthermore, OVs can elicit both local and systemic anticancer immune responses while specifically infecting and lysing tumour cells. These characteristics render them a promising therapeutic approach for paediatric brain tumours (PBTs). PBTs are frequently marked by a cold tumour immune microenvironment (TIME), which suppresses immunotherapies. Recent preclinical and clinical studies have demonstrated the capability of OVs to induce a proinflammatory immune response, thereby modifying the TIME. In-depth insights into the effect of OVs on different cell types in the TIME may therefore provide a compelling basis for using OVs in combination with other immunotherapy modalities. However, certain limitations persist in our understanding of oncolytic viruses' ability to regulate the TIME to enhance anti-tumour activity. These limitations primarily stem from the translational limitations of model systems, the difficulties associated with tracking reliable markers of efficacy throughout the course of treatment and the role of pre-existing viral immunity. In this review, we describe the different alterations observed in the TIME in PBTs due to OV treatment, combination therapies of OVs with different immunotherapies and the hurdles limiting the development of effective OV therapies while suggesting future directions based on existing evidence.

New hopes for the breast cancer treatment: perspectives on the oncolytic virus therapy.

Oncolytic virus (OV) therapy has emerged as a promising frontier in cancer treatment, especially for solid tumours. While immunotherapies like immune checkpoint inhibitors and CAR-T cells have demonstrated impressive results, their limitations in inducing complete tumour regression have spurred researchers to explore new approaches targeting tumours resistant to current immunotherapies. OVs, both natural and genetically engineered, selectively replicate within cancer cells, inducing their lysis while sparing normal tissues. Recent advancements in clinical research and genetic engineering have enabled the development of targeted viruses that modify the tumour microenvironment, triggering anti-tumour immune responses and exhibiting synergistic effects with other cancer therapies. Several OVs have been studied for breast cancer treatment, including adenovirus, protoparvovirus, vaccinia virus, reovirus, and herpes simplex virus type I (HSV-1). These viruses have been modified or engineered to enhance their tumour-selective replication, reduce toxicity, and improve oncolytic properties.Newer generations of OVs, such as Oncoviron and Delta-24-RGD adenovirus, exhibit heightened replication selectivity and enhanced anticancer effects, particularly in breast cancer models. Clinical trials have explored the efficacy and safety of various OVs in treating different cancers, including melanoma, nasopharyngeal carcinoma, head and neck cancer, and gynecologic malignancies. Notably, Talimogene laherparepvec (T-VEC) and Oncorine have. been approved for advanced melanoma and nasopharyngeal carcinoma, respectively. However, adverse effects have been reported in some cases, including flu-like symptoms and rare instances of severe complications such as fistula formation. Although no OV has been approved specifically for breast cancer treatment, ongoing preclinical clinical trials focus on four groups of viruses. While mild adverse effects like low-grade fever and nausea have been observed, the effectiveness of OV monotherapy in breast cancer remains insufficient. Combination strategies integrating OVs with chemotherapy, radiotherapy, or immunotherapy, show promise in improving therapeutic outcomes. Oncolytic virus therapy holds substantial potential in breast cancer treatment, demonstrating safety in trials. Multi-approach strategies combining OVs with conventional therapies exhibit more promising therapeutic effects than monotherapy, signalling a hopeful future for OV-based breast cancer treatments.

The Recombinant Oncolytic Virus VV-GMCSF-Lact and Chemotherapy Drugs against Human Glioma.

Virotherapy is one of the perspective technologies in the treatment of malignant neoplasms. Previously, we have developed oncolytic vaccinia virus VV-GMCSF-Lact and its high cytotoxic activity and antitumor efficacy against glioma was shown. In this work, using immortalized and patient-derived cells with different sensitivity to VV-GMCSF-Lact, we evaluated the cytotoxic effect of chemotherapy agents. Additionally, we studied the combination of VV-GMCSF-Lact with temozolomide which is the most preferred drug for glioma treatment. Experimental results indicate that first adding temozolomide and then the virus to the cells is inherently more efficient than dosing it in the reverse order. Testing these regimens in the U87 MG xenograft glioblastoma model confirmed this effect, as assessed by tumor growth inhibition index and histological analysis. Moreover, VV-GMCSF-Lact as monotherapy is more effective against U87 MG glioblastoma xenografts comparing temozolomide.

Zika Virus: A Neurotropic Warrior against High-Grade Gliomas-Unveiling Its Potential for Oncolytic Virotherapy.

Gliomas account for approximately 75-80% of all malignant primary tumors in the central nervous system (CNS), with glioblastoma multiforme (GBM) considered the deadliest. Despite aggressive treatment involving a combination of chemotherapy, radiotherapy, and surgical intervention, patients with GBM have limited survival rates of 2 to 5 years, accompanied by a significant decline in their quality of life. In recent years, novel management strategies have emerged, such as immunotherapy, which includes the development of vaccines or T cells with chimeric antigen receptors, and oncolytic virotherapy (OVT), wherein wild type (WT) or genetically modified viruses are utilized to selectively lyse tumor cells. In vitro and in vivo studies have shown that the Zika virus (ZIKV) can infect glioma cells and induce a robust oncolytic activity. Consequently, interest in exploring this virus as a potential oncolytic virus (OV) for high-grade gliomas has surged. Given that ZIKV actively circulates in Colombia, evaluating its neurotropic and oncolytic capabilities holds considerable national and international importance, as it may emerge as an alternative for treating highly complex gliomas. Therefore, this literature review outlines the generalities of GBM, the factors determining ZIKV's specific tropism for nervous tissue, and its oncolytic capacity. Additionally, we briefly present the progress in preclinical studies supporting the use of ZIKV as an OVT for gliomas.

Oncolytic Adenovirus for the Targeting of Paclitaxel-Resistant Breast Cancer Stem Cells.

Adjuvant systemic therapies effectively reduce the risk of breast cancer recurrence and metastasis, but therapy resistance can develop in some patients due to breast cancer stem cells (BCSCs). Oncolytic adenovirus (OAd) represents a promising therapeutic approach as it can specifically target cancer cells. However, its potential to target BCSCs remains unclear. Here, we evaluated a Cox-2 promoter-controlled, Ad5/3 fiber-modified OAd designed to encode the human sodium iodide symporter (hNIS) in breast cancer models. To confirm the potential of OAds to target BCSCs, we employed BCSC-enriched estrogen receptor-positive (ER+) paclitaxel-resistant (TaxR) cells and tumorsphere assays. OAd-hNIS demonstrated significantly enhanced binding and superior oncolysis in breast cancer cells, including ER+ cells, while exhibiting no activity in normal mammary epithelial cells. We observed improved NIS expression as the result of adenovirus death protein deletion. OAd-hNIS demonstrated efficacy in targeting TaxR BCSCs, exhibiting superior killing and hNIS expression compared to the parental cells. Our vector was capable of inhibiting tumorsphere formation upon early infection and reversing paclitaxel resistance in TaxR cells. Importantly, OAd-hNIS also destroyed already formed tumorspheres seven days after their initiation. Overall, our findings highlight the promise of OAd-hNIS as a potential tool for studying and targeting ER+ breast cancer recurrence and metastasis.

p53-Armed Oncolytic Virotherapy Improves Radiosensitivity in Soft-Tissue Sarcoma by Suppressing BCL-xL Expression.

Soft-tissue sarcoma (STS) is a heterogeneous group of rare tumors originating predominantly from the embryonic mesoderm. Despite the development of combined modalities including radiotherapy, STSs are often refractory to antitumor modalities, and novel strategies that improve the prognosis of STS patients are needed. We previously demonstrated the therapeutic potential of two telomerase-specific replication-competent oncolytic adenoviruses, OBP-301 and tumor suppressor p53-armed OBP-702, in human STS cells. Here, we demonstrate in vitro and in vivo antitumor effects of OBP-702 in combination with ionizing radiation against human STS cells (HT1080, NMS-2, SYO-1). OBP-702 synergistically promoted the antitumor effect of ionizing radiation in the STS cells by suppressing the expression of B-cell lymphoma-X large (BCL-xL) and enhancing ionizing radiation-induced apoptosis. The in vivo experiments demonstrated that this combination therapy significantly suppressed STS tumors' growth. Our results suggest that OBP-702 is a promising antitumor reagent for promoting the radiosensitivity of STS tumors.

Oncolytic viral therapy for gliomas: Advances in the mechanisms and approaches to delivery.

Glioma is a diverse category of tumors originating from glial cells encompasses various subtypes, based on the specific type of glial cells involved. The most aggressive is glioblastoma multiforme (GBM), which stands as the predominant primary malignant tumor within the central nervous system in adults. Despite the application of treatment strategy, the median survival rate for GBM patients still hovers around 15 months. Oncolytic viruses (OVs) are artificially engineered viruses designed to selectively target and induce apoptosis in cancer cells. While clinical trials have demonstrated encouraging results with intratumoral OV injections for some cancers, applying this approach to GBM presents unique challenges. Here we elaborate on current trends in oncolytic viral therapy and their delivery methods. We delve into the various methods of delivering OVs for therapy, exploring their respective advantages and disadvantages and discussing how selecting the optimal delivery method can enhance the efficacy of this innovative treatment approach.

Sindbis Virus Vaccine Platform: A Promising Oncolytic Virus-Mediated Approach for Ovarian Cancer Treatment.

This review article provides a comprehensive overview of a novel Sindbis virus vaccine platform as potential immunotherapy for ovarian cancer patients. Ovarian cancer is the most lethal of all gynecological malignancies. The majority of high-grade serous ovarian cancer (HGSOC) patients are diagnosed with advanced disease. Current treatment options are very aggressive and limited, resulting in tumor recurrences and 50-60% patient mortality within 5 years. The unique properties of armed oncolytic Sindbis virus vectors (SV) in vivo have garnered significant interest in recent years to potently target and treat ovarian cancer. We discuss the molecular biology of Sindbis virus, its mechanisms of action against ovarian cancer cells, preclinical in vivo studies, and future perspectives. The potential of Sindbis virus-based therapies for ovarian cancer treatment holds great promise and warrants further investigation. Investigations using other oncolytic viruses in preclinical studies and clinical trials are also presented.

Tumor-targeted delivery of copper-manganese biomineralized oncolytic adenovirus for colorectal cancer immunotherapy.

Oncolytic viral therapy (OVT) is a novel anti-tumor immunotherapy approach, specifically replicating within tumor cells. Currently, oncolytic viruses are mainly administered by intratumoral injection. However, achieving good results for distant metastatic tumors is challenging. In this study, a multifunctional oncolytic adenovirus, OA@CuMnCs, was developed using bimetallic ions copper and manganese. These metal cations form a biomineralized coating on the virus's surface, reducing immune clearance. It is known that viruses upregulate the expression of PD-L1. Copper ions in OA@CuMnCs can decrease the PD-L1 expression of tumor cells, thereby promoting immune cell-related factor release. This process involves antigen presentation and the combination of immature dendritic cells, transforming them into mature dendritic cells. It changes "cold" tumors into "hot" tumors, further inducing immunogenic cell death. While oncolytic virus replication requires oxygen, manganese ions in OA@CuMnCs can react with endogenous hydrogen peroxide. This reaction produces oxygen, enhancing the virus's replication ability and the tumor lysis effect. Thus, this multifunctionally coated OA@CuMnCs demonstrates potent amplification in immunotherapy efficacy, and shows great potential for further clinical OVT. STATEMENT OF SIGNIFICANCE: Oncolytic virus therapy (OVs) is a new anti-tumor immunotherapy method that can specifically replicate in tumor cells. Although the oncolytic virus can achieve a therapeutic effect on some non-metastatic tumors through direct intratumoral injection, there are still three major defects in the treatment of metastatic tumors: immune response, hypoxia effect, and administration route. Various studies have shown that the immune response in vivo can be overcome by modifying or wrapping the surface protein of the oncolytic virus. In this paper, a multifunctional coating of copper and manganese was prepared by combining the advantages of copper and manganese ions. The coating has a simple preparation method and mild conditions, and can effectively enhance tumor immunotherapy.

Optimal strategies of oncolytic virus-bortezomib therapy via the apoptotic, necroptotic, and oncolysis signaling network.

Bortezomib and oncolytic virotherapy are two emerging targeted cancer therapies. Bortezomib, a proteasome inhibitor, disrupts protein degradation in cells, leading to the accumulation of unfolded proteins that induce apoptosis. On the other hand, virotherapy uses genetically modified oncolytic viruses (OVs) to infect cancer cells, trigger cell lysis, and activate anti-tumor response. Despite progress in cancer treatment, identifying administration protocols for therapeutic agents remains a significant concern, aiming to strike a balance between efficacy, minimizing toxicity, and administrative costs. In this work, optimal control theory was employed to design a cost-effective and efficient co-administration protocols for bortezomib and OVs that could significantly diminish the population of cancer cells via the cell death program with the NF$ \kappa $B-BAX-RIP1 signaling network. Both linear and quadratic control strategies were explored to obtain practical treatment approaches by adapting necroptosis protocols to efficient cell death programs. Our findings demonstrated that a combination therapy commencing with the administration of OVs followed by bortezomib infusions yields an effective tumor-killing outcome. These results could provide valuable guidance for the development of clinical administration protocols in cancer treatment.

Oncolytic vaccinia virus immunotherapy antagonizes image-guided radiotherapy in mouse mammary tumor models.

Ionizing radiation (IR) and oncolytic viruses are both used to treat cancer, and the effectiveness of both agents depends upon stimulating an immune response against the tumor. In this study we tested whether combining image guided ionizing radiation (IG-IR) with an oncolytic vaccinia virus (VACV) could yield a better therapeutic response than either treatment alone. ΔF4LΔJ2R VACV grew well on irradiated human and mouse breast cancer cells, and the virus can be combined with 4 or 8 Gy of IR to kill cells in an additive or weakly synergistic manner. To test efficacy in vivo we used immune competent mice bearing orthotopic TUBO mammary tumors. IG-IR worked well with 10 Gy producing 80% complete responses, but this was halved when the tumors were treated with VACV starting 2 days after IG-IR. VACV monotherapy was ineffective in this model. The antagonism was time dependent as waiting for 21 days after IG-IR eliminated the inhibitory effect but without yielding any further benefits over IR alone. In irradiated tumors, VACV replication was also lower, suggesting that irradiation created an environment that did not support infection as well in vivo as in vitro. A study of how four different treatment regimens affected the immune composition of the tumor microenvironment showed that treating irradiated tumors with VACV altered the immunological profiles in tumors exposed to IR or VACV alone. We detected more PD-1 and PD-L1 expression in tumors exposed to IR+VACV but adding an αPD-1 antibody to the protocol did not change the way VACV interferes with IG-IR therapy. VACV encodes many immunosuppressive gene products that may interfere with the ability of radiotherapy to induce an effective anti-tumor immune response through the release of danger-associated molecular patterns. These data suggest that infecting irradiated tumors with VACV, too soon after exposure, may interfere in the innate and linked adaptive immune responses that are triggered by radiotherapy to achieve a beneficial impact.

Revolutionizing cancer treatment: the power of bi- and tri-specific T-cell engagers in oncolytic virotherapy.

Bi- or tri-specific T cell engagers (BiTE or TriTE) are recombinant bispecific proteins designed to stimulate T-cell immunity directly, bypassing antigen presentation by antigen-presenting cells (APCs). However, these molecules suffer from limitations such as short biological half-life and poor residence time in the tumor microenvironment (TME). Fortunately, these challenges can be overcome when combined with OVs. Various strategies have been developed, such as encoding secretory BiTEs within OV vectors, resulting in improved targeting and activation of T cells, secretion of key cytokines, and bystander killing of tumor cells. Additionally, oncolytic viruses armed with BiTEs have shown promising outcomes in enhancing major histocompatibility complex I antigen (MHC-I) presentation, T-cell proliferation, activation, and cytotoxicity against tumor cells. These combined approaches address tumor heterogeneity, drug delivery, and T-cell infiltration, offering a comprehensive and effective solution. This review article aims to provide a comprehensive overview of Bi- or TriTEs and OVs as promising therapeutic approaches in the field of cancer treatment. We summarize the cutting-edge advancements in oncolytic virotherapy immune-related genetic engineering, focusing on the innovative combination of BiTE or TriTE with OVs.

An oncolytic vaccinia virus encoding hyaluronidase reshapes the extracellular matrix to enhance cancer chemotherapy and immunotherapy.

BACKGROUND: The redundant extracellular matrix (ECM) within tumor microenvironment (TME) such as hyaluronic acid (HA) often impairs intratumoral dissemination of antitumor drugs. Oncolytic viruses (OVs) are being studied extensively for cancer therapy either alone or in conjunction with chemotherapy and immunotherapy. Here, we designed a novel recombinant vaccinia virus encoding a soluble version of hyaluronidase Hyal1 (OVV-Hyal1) to degrade the HA and investigated its antitumor effects in combination with chemo drugs, polypeptide, immune cells, and antibodies. METHODS: We constructed a recombinant oncolytic vaccinia virus encoding the hyaluronidase, and investigated its function in remodeling the ECM of the TME, the antitumor efficacy both in vitro and in several murine solid tumors either alone, or in combination with chemo drugs including doxorubicin and gemcitabine, with polypeptide liraglutide, with immune therapeutics such as PD-L1/PD-1 blockade, CD47 antibody, and with CAR-T cells. RESULTS: Compared with control OVV, intratumoral injection of OVV-Hyal1 showed superior antitumor efficacies in a series of mouse subcutaneous tumor models. Moreover, HA degradation by OVV-Hyal1 resulted in increased intratumoral dissemination of chemo drugs, infiltration of T cells, NK cells, macrophages, and activation of CD8+ T cells. When OVV-Hyal1 was combined with some antitumor therapeutics, for example, doxorubicin, gemcitabine, liraglutide, anti-PD-1, anti-CD47 blockade, or CAR-T cells, more profound therapeutic outcomes were obtained. CONCLUSIONS: OVV-Hyal1 effectively degrades HA to reshape the TME, therefore overcoming some major hurdles in current cancer therapy, such as limited OVs spread, unfavored dissemination of chemo drugs, polypeptides, antibodies, and insufficient infiltration of effector immune cells. OVV-Hyal1 holds the promise to improve the antitumor outcomes of current cancer therapeutics.