CD137 and PD-L1 targeting with immunovirotherapy induces a potent and durable antitumor immune response in glioblastoma models

Comparison of the L3-23K and L5-Fiber Regions for Arming the Oncolytic Adenovirus Ad5-Delta-24-RGD with Reporter and Therapeutic Transgenes

The insertion of a transgene downstream of the L3-23K or L5-Fiber region was reported as a vital strategy for arming E3 non-deleted oncolytic adenoviruses. However, depending on the percentage of codons with G/C at the third base position (GC3%) and the type of splicing acceptor, an insert downstream of the L5-Fiber region may substantially affect virus fitness. Since the insertion of transgenes downstream of the L3-23K and L5-Fiber regions has never been compared in terms of their expression levels and impact on virus fitness, we assessed the total virus yield, cytolytic efficacy, and plaque size of Ad5-delta-24-RGD (Ad5Δ24RGD) armed with EGFP, FLuc, the suppressor of RNA silencing p19, soluble wild-type human/mouse and high-affinity human programmed cell death receptor-1 (PD-1/PDCD1) ectodomains, and soluble human hyaluronidase PH20/SPAM1. The insertion of transgenes downstream of the L3-23K region ensures their production at considerably higher levels. However, the insertion of transgenes downstream of either region differentially and unpredictably affects the oncolytic potency of Ad5Δ24RGD, which cannot be explained by GC3% or expression level alone. Surprisingly, the expression of the human and mouse PD-1 ectodomains with 83.1% and 70.1% GC3%, respectively, does not affect cytolytic efficacy but increases the plaque size in a cell line-dependent manner.

Immunodominant antiviral T cell responses outcompete immuno-subdominant antitumor responses to reduce the efficacy of oncolytic viroimmunotherapy

The paradigm in the field of oncolytic virotherapy proposes that tumor cell killing by an oncolytic virus (OV) culminates in the priming of antitumor CD8 T cells. However, this ignores the impact a highly immunodominant antiviral response against the OV has on the antitumor response which has been weakened by mechanisms of central tolerance. Here, we show that inflammatory Vesicular Stomatitis Virus (VSV) failed to prime an adoptively transferred, or pre-existing, population of tumor-reactive T cells. Combination with αPD1 immune checkpoint blockade therapy improved survival only when VSV expressed tumor associated antigens (TAA). These data show that, in this model, the highly inflammatory OV VSV alone actively outcompetes antitumor immunity. However, we also show that viral expression of a mutant near-self TAA can break central tolerance expanding heteroclitic self-reactive and near-self-reactive T cells, thus overcoming viral immunodominance by promoting tumor-specific T cell proliferation in parallel with expanding antiviral T cells.

A Novel Designed Anti-PD-L1/OX40 Bispecific Antibody Augments Both Peripheral and Tumor-Associated Immune Responses for Boosting Antitumor Immunity

Bispecific antibodies (BsAb) combining simultaneous PD-L1 blockade and conditional costimulatory receptor activation have been developed to improve immune checkpoint therapy response. However, several PD-L1-based BsAbs have encountered clinical challenges, including insufficient activity or unexpected toxicity. In this study, we propose OX40 as a more suitable target partner for PD-L1-based BsAb design compared with ongoing clinical partners (CD27 and 4-1BB). We present a novel Fc-silenced tetravalent PD-L1/OX40 BsAb (EMB-09), which efficiently blocks PD-1/PD-L1 interactions and induces PD-L1-dependent OX40 activation, leading to enhanced T-cell activation. EMB-09 demonstrated improved antitumor activity compared with the anti-PD-L1 mAb. Significantly, EMB-09 activated effector memory T cells in the peripheral immune system and promoted the influx of stem-like CD8+ T cells into the tumor site, resulting in a more active phenotype of CD8+ tumor-infiltrating lymphocytes. In an ongoing first-in-human study in patients with advanced refractory solid tumors (NCT05263180), EMB-09 demonstrated a consistent pharmacodynamic response and early efficacy signals.

The role of IL‑17, IFN‑γ, 4‑1BBL and tumour‑infiltrating lymphocytes in the occurrence, development and prognosis of pancreatic cancer

Immunotherapy has made progress in the treatment of tumours; however, in patients with pancreatic cancer, immunotherapy has not achieved effective results. The present study investigated changes in the immune microenvironment during tumour development and progression, and the relationship between the immune microenvironment and prognosis, to clarify the mechanism of immune escape in pancreatic cancer. A total of 40 patients with pancreatic cancer (including 22 with stage I-II disease and 18 with stage III-IV disease) and 20 patients with chronic pancreatitis were included in the present study. The expression of CD3, CD4, CD8, CD56, IFN-γ, IL-17 and 4-1BBL was assessed by immunohistochemistry, and the mRNA expression levels were detected by reverse transcription-quantitative PCR (RT-qPCR). The clinicopathological characteristics and prognoses of patients with pancreatic cancer were analysed to further explore the role of IL-17, IFN-γ, 4-1BBL and tumour-infiltrating lymphocytes in pancreatic cancer. Notably, the expression levels of CD3, CD8, CD56, IFN-γ and 4-1BBL in patients with stages I-II and III-IV cancer were lower than those in patients with chronic pancreatitis (P<0.05), especially in patients with stage III-IV cancer (P<0.05). In addition, the expression of IL-17 in patients with stages I-II and III-IV cancer was greater than in patients with chronic pancreatitis (P<0.05), especially in patients with stage III-IV cancer (P<0.05). The RT-qPCR results regarding CD3, CD4, CD8, CD56, IFN-γ and IL-17 were almost the same as those obtained from immunohistochemical analysis; however, the mRNA expression levels of 4-1BBL were not significantly different between stages I-II and III-IV. Furthermore, patients with pancreatic cancer with higher expression levels of CD3, CD8, CD56, IFN-γ and 4-1BBL exhibited longer survival, whereas those with higher expression of IL-17 had a shorter survival time. The expression levels of CD3, CD8, CD56, cytokines IL-17 and IFN-γ, and costimulatory molecule 4-1BBL were revealed to be related to the degree of differentiation, Tumour-Node-Metastasis staging and the prognosis of pancreatic cancer, and may serve as novel immunological indicators for evaluating the condition and treatment effectiveness in patients with pancreatic cancer.

The emerging field of viroimmunotherapy for pediatric brain tumors

Pediatric brain tumors are the most common solid tumors in children. Even to date, with the advances in multimodality therapeutic management, survival outcomes remain dismal in some types of tumors, such as pediatric-type diffuse high-grade gliomas or central nervous system embryonal tumors. Failure to understand the complex molecular heterogeneity and the elusive tumor and microenvironment interplay continues to undermine therapeutic efficacy. Developing a strategy that would improve survival for these fatal tumors remains unmet in pediatric neuro-oncology. Oncolytic viruses (OVs) are emerging as a feasible, safe, and promising therapy for brain tumors. The new paradigm in virotherapy implies that the direct cytopathic effect is followed, under certain circumstances, by an antitumor immune response responsible for the partial or complete debulking of the tumor mass. OVs alone or combined with other therapeutic modalities have been primarily used in adult neuro-oncology. A surge in encouraging preclinical studies in pediatric brain tumor models recently led to the clinical translation of OVs with encouraging results in these tumors. In this review, we summarize the different virotherapy tested in preclinical and clinical studies in pediatric brain tumors, and we discuss the limitations and future avenues necessary to improve the response of these tumors to this type of therapy.

CXCR7 activation evokes the anti-PD-L1 antibody against glioblastoma by remodeling CXCL12-mediated immunity

The interaction between glioblastoma cells and glioblastoma-associated macrophages (GAMs) influences the immunosuppressive tumor microenvironment, leading to ineffective immunotherapies. We hypothesized that disrupting the communication between tumors and macrophages would enhance the efficacy of immunotherapies. Transcriptomic analysis of recurrent glioblastoma specimens indicated an enhanced neuroinflammatory pathway, with CXCL12 emerging as the top-ranked gene in secretory molecules. Single-cell transcriptome profiling of naïve glioblastoma specimens revealed CXCL12 expression in tumor and myeloid clusters. An analysis of public glioblastoma datasets has confirmed the association of CXCL12 with disease and PD-L1 expression. In vitro studies have demonstrated that exogenous CXCL12 induces pro-tumorigenic characteristics in macrophage-like cells and upregulated PD-L1 expression through NF-κB signaling. We identified CXCR7, an atypical receptor for CXCL12 predominantly present in tumor cells, as a negative regulator of CXCL12 expression by interfering with extracellular signal-regulated kinase activation. CXCR7 knockdown in a glioblastoma mouse model resulted in worse survival outcomes, increased PD-L1 expression in GAMs, and reduced CD8+ T-cell infiltration compared with the control group. Ex vivo T-cell experiments demonstrated enhanced cytotoxicity against tumor cells with a selective CXCR7 agonist, VUF11207, reversing GAM-induced immunosuppression in a glioblastoma cell-macrophage-T-cell co-culture system. Notably, VUF11207 prolonged survival and potentiated the anti-tumor effect of the anti-PD-L1 antibody in glioblastoma-bearing mice. This effect was mitigated by an anti-CD8β antibody, indicating the synergistic effect of VUF11207. In conclusion, CXCL12 conferred immunosuppression mediated by pro-tumorigenic and PD-L1-expressing GAMs in glioblastoma. Targeted activation of glioblastoma-derived CXCR7 inhibits CXCL12, thereby eliciting anti-tumor immunity and enhancing the efficacy of anti-PD-L1 antibodies.

Treatment advances in high-grade gliomas

High-grade gliomas (HGG) pose significant challenges in modern tumour therapy due to the distinct biological properties and limitations of the blood-brain barrier. This review discusses recent advancements in HGG treatment, particularly in the context of immunotherapy and cellular therapy. Initially, treatment strategies focus on targeting tumour cells guided by the molecular characteristics of various gliomas, encompassing chemotherapy, radiotherapy and targeted therapy for enhanced precision. Additionally, technological enhancements are augmenting traditional treatment modalities. Furthermore, immunotherapy, emphasising comprehensive tumour management, has gained widespread attention. Immune checkpoint inhibitors, vaccines and CAR-T cells exhibit promising efficacy against recurrent HGG. Moreover, emerging therapies such as tumour treating fields (TTFields) offer additional treatment avenues for patients with HGG. The combination of diverse treatments holds promise for improving the prognosis of HGG, particularly in cases of recurrence.

Glioma stem cells remodel immunotolerant microenvironment in GBM and are associated with therapeutic advancements

Glioma is the most common primary tumor of the central nervous system (CNS). Glioblastoma (GBM) is incurable with current treatment strategies. Additionally, the treatment of recurrent GBM (rGBM) is often referred to as terminal treatment, necessitating hospice-level care and management. The presence of the blood-brain barrier (BBB) gives GBM a more challenging or "cold" tumor microenvironment (TME) than that of other cancers and gloma stem cells (GSCs) play an important role in the TME remodeling, occurrence, development and recurrence of giloma. In this review, our primary focus will be on discussing the following topics: niche-associated GSCs and macrophages, new theories regarding GSC and TME involving pyroptosis and ferroptosis in GBM, metabolic adaptations of GSCs, the influence of the cold environment in GBM on immunotherapy, potential strategies to transform the cold GBM TME into a hot one, and the advancement of GBM immunotherapy and GBM models.

Limited Effects of Class II Transactivator-Based Immunotherapy in Murine and Human Glioblastoma

BACKGROUND

The major histocompatibility complex type II is downregulated in glioblastoma (GB) due to the silencing of the major transcriptional regulator class II transactivator (CIITA). We investigated the pro-immunogenic potential of CIITA overexpression in mouse and human GB.

METHODS

The intracerebral growth of wildtype GL261-WT cells was assessed following contralateral injection of GL261-CIITA cells or flank injections with GL261-WT or GL261-CIITA cells. Splenocytes obtained from mice implanted intracerebrally with GL261-WT, GL261-CIITA cells or phosphate buffered saline (PBS) were transferred to other mice and subsequently implanted intracerebrally with GL261-WT. Human GB cells and (syngeneic) GB-infiltrating immune cells were isolated from surgical samples and co-cultured with GB cells expressing CIITA or not, followed by RT-qPCR assessment of the expression of key immune regulators.

RESULTS

Intracerebral vaccination of GL261-CIITA significantly reduced the subsequent growth of GL261-WT cells implanted contralaterally. Vaccination with GL261-WT or -CIITA subcutaneously, however, equivalently retarded the intracerebral growth of GL261 cells. Adoptive cell transfer experiments showed a similar antitumor potential of lymphocytes harvested from mice implanted intracerebrally with GL261-WT or -CIITA. Human GB-infiltrating myeloid cells and lymphocytes were not activated when cultured with CIITA-expressing GB cells. Tumor-infiltrating NK cells remained mostly inactivated when in co-culture with GB cells, regardless of CIITA.

CONCLUSION

these results question the therapeutic potential of CIITA-mediated immunotherapy in glioblastoma.

Novel Therapies in Glioblastoma Treatment: Review of Glioblastoma; Current Treatment Options; and Novel Oncolytic Viral Therapies

One of the most prevalent primary malignant brain tumors is glioblastoma (GB). About 6 incidents per 100,000 people are reported annually. Most frequently, these tumors are linked to a poor prognosis and poor quality of life. There has been little advancement in the treatment of GB. In recent years, some innovative medicines have been tested for the treatment of newly diagnosed cases of GB and recurrent cases of GB. Surgery, radiotherapy, and alkylating chemotherapy are all common treatments for GB. A few of the potential alternatives include immunotherapy, tumor-treating fields (TTFs), and medications that target specific cellular receptors. To provide new multimodal therapies that focus on the molecular pathways implicated in tumor initiation and progression in GB, novel medications, delivery technologies, and immunotherapy approaches are being researched. Of these, oncolytic viruses (OVs) are among the most recent. Coupling OVs with certain modern treatment approaches may have significant benefits for GB patients. Here, we discuss several OVs and how they work in conjunction with other therapies, as well as virotherapy for GB. The study was based on the PRISMA guidelines. Systematic retrieval of information was performed on PubMed. A total of 307 articles were found in a search on oncolytic viral therapies for glioblastoma. Out of these 83 articles were meta-analyses, randomized controlled trials, reviews, and systematic reviews. A total of 42 articles were from the years 2018 to 2023. Appropriate studies were isolated, and important information from each of them was understood and entered into a database from which the information was used in this article. One of the most prevalent malignant brain tumors is still GB. Significant promise and opportunity exist for oncolytic viruses in the treatment of GB and in boosting immune response. Making the most of OVs in the treatment of GB requires careful consideration and evaluation of a number of its application factors.

Advances in oncolytic herpes simplex virus and adenovirus therapy for recurrent glioma

Recurrent glioma treatment is challenging due to molecular heterogeneity and treatment resistance commonly observed in these tumors. Researchers are actively pursuing new therapeutic strategies. Oncolytic viruses have emerged as a promising option. Oncolytic viruses selectively replicate within tumor cells, destroying them and stimulating the immune system for an enhanced anticancer response. Among Oncolytic viruses investigated for recurrent gliomas, oncolytic herpes simplex virus and oncolytic adenovirus show notable potential. Genetic modifications play a crucial role in optimizing their therapeutic efficacy. Different generations of replicative conditioned oncolytic human adenovirus and oncolytic HSV have been developed, incorporating specific modifications to enhance tumor selectivity, replication efficiency, and immune activation. This review article summarizes these genetic modifications, offering insights into the underlying mechanisms of Oncolytic viruses' therapy. It also aims to identify strategies for further enhancing the therapeutic benefits of Oncolytic viruses. However, it is important to acknowledge that additional research and clinical trials are necessary to establish the safety, efficacy, and optimal utilization of Oncolytic viruses in treating recurrent glioblastoma.

Promises of oncolytic viral therapy for adult and children with brain glioma

PURPOSE OF REVIEW

The purpose of this review is to give an overview of early clinical studies addressing the safety and efficacy of oncolytic immunovirotherapy in adults and children with brain gliomas, and to highlight the extensive potential for the development of this therapeutic alternative.

RECENT FINDINGS

The lack of curative treatments and poor prognosis of high-grade glioma patients warrants research on innovative therapeutic alternatives such as oncolytic immunovirotherapy. Engineered modified oncolytic viruses exert both a direct lytic effect on tumor cells and a specific antitumor immune response. Early clinical trials of different DNA and RNA oncolytic viruses, mainly Herpes Simplex Virus Type-1 and adenovirus based platforms, have consistently demonstrated an acceptable safety profile, hints of efficacy and the potential of this therapy to reshape the tumor microenvironment in both adult and pediatric patients with glioma, thus constituting the basis for the development of more advanced clinical trials.

SUMMARY

The future landscape of oncolytic immunovirotherapy is still plenty of challenges and opportunities to enable its full therapeutic potential in both adult and children with brain gliomas.

Immunotherapy: a promising approach for glioma treatment

Gliomas are the most prevalent primary malignant brain tumors worldwide, with glioblastoma (GBM) being the most common and aggressive type. Despite two decades of relentless pursuit in exploring novel therapeutic approaches for GBM, there is limited progress in improving patients' survival outcomes. Numerous obstacles impede the effective treatment of GBM, including the immunosuppressive tumor microenvironment (TME), the blood-brain barrier, and extensive heterogeneity. Despite these challenges, immunotherapies are emerging as a promising avenue that may offer new hope for the treatment of gliomas. There are four main types of immunotherapies for gliomas, immune checkpoint blockades, chimeric antigen receptor T-cell therapies, vaccines, and oncolytic viruses. In addition, gene therapy, bispecific antibody therapy, and combine therapy are also briefly introduced in this review. The significant role of TME in the process of immunotherapies has been emphasized in many studies. Although immunotherapy is a promising treatment for gliomas, enormous effort is required to overcome the existing barriers to its success. Owing to the rapid development and increasing attention paid to immunotherapies for gliomas, this article aims to review the recent advances in immunotherapies for gliomas.

The diversity and dynamics of tumor-associated macrophages in recurrent glioblastoma

Despite tremendous efforts to exploit effective therapeutic strategies, most glioblastoma (GBM) inevitably relapse and become resistant to therapies, including radiotherapy and immunotherapy. The tumor microenvironment (TME) of recurrent GBM (rGBM) is highly immunosuppressive, dominated by tumor-associated macrophages (TAMs). TAMs consist of tissue-resident microglia and monocyte-derived macrophages (MDMs), which are essential for favoring tumor growth, invasion, angiogenesis, immune suppression, and therapeutic resistance; however, restricted by the absence of potent methods, the heterogeneity and plasticity of TAMs in rGBM remain incompletely investigated. Recent application of single-cell technologies, such as single-cell RNA-sequencing has enabled us to decipher the unforeseen diversity and dynamics of TAMs and to identify new subsets of TAMs which regulate anti-tumor immunity. Here, we first review hallmarks of the TME, progress and challenges of immunotherapy, and the biology of TAMs in the context of rGBM, including their origins, categories, and functions. Next, from a single-cell perspective, we highlight recent findings regarding the distinctions between tissue-resident microglia and MDMs, the identification and characterization of specific TAM subsets, and the dynamic alterations of TAMs during tumor progression and treatment. Last, we briefly discuss the potential of TAM-targeted strategies for combination immunotherapy in rGBM. We anticipate the comprehensive understanding of the diversity and dynamics of TAMs in rGBM will shed light on further improvement of immunotherapeutic efficacy in rGBM.

Oncolytic vaccinia virus acts synergistically with anti-PD-L1 antibody to enhance the killing of colon cancer cells by CD8+ T cells

Both oncolytic vaccinia virus (OVV) and anti-PD-L1 antibody hold promise in cancer immunotherapy. Herein, we aimed to explore the possible synergistic effects of OVV and anti-PD-L1 on the growth and metastasis of colon cancer (CC) in mouse models. Microarray profiling of CC-related genes was first conducted. Expression of PD-L1 in CC tissues was predicted by TCGA and verified by flow cytometry and RT-qPCR. Then, mouse CC cell lines stably carrying luciferase MC38-luc and CT26-luc were infected with recombinant double-deleted vaccinia virus (vvDD) to evaluate the effect of vvDD on cell viability. The data indicated that PD-L1 was highly expressed in CC tissues and cells following vvDD infection. MC38-luc cells were inoculated into mice to construct CC-bearing mouse models, which were treated with vvDD or combined with anti-PD-L1, with tumor growth, metastasis, survival, and the immune environment analyzed. It was found that OVV combined with anti-PD-L1 antibody led to lower tumor burden and growth and higher survival rates than individual treatment in CC-bearing mice. In addition, this combination exerted a remote effect on the untreated subcutaneous tumors in the lateral abdomen, thus suppressing the tumor metastasis. Furthermore, combined therapy of OVV with anti-PD-L1 antibody activated CD8⁺ T cells, reduced exhaustion of CD8⁺ T cells, and enhanced their immune response, strengthening the killing of CC cells and inhibiting tumor growth and metastasis. In conclusion, our findings provide mechanistic insights into the action and efficacy of OVV as an immunomodulatory agent combined with the anti-PD-L1 antibody for the treatment of CC.

Oncolytic virotherapy for the treatment of pediatric brainstem gliomas

Diffuse intrinsic pontine glioma (DIPG) is the most frequent brainstem glioma and the most lethal brain tumor in childhood. Despite transient benefit with radiotherapy, the prognosis of children with this disease remains dismal with severe neurological morbidity and median survival less than 12months. Oncolytic immunovirotherapy is emerging as a potential therapeutic approach in neuro-oncology. The oncolytic adenovirus Delta-24-RGD has shown efficacy in adult patients with recurrent GBM. Our group has demonstrated that Delta-24-RGD has oncolytic activity and triggers immune response in preclinical models of DIPG, and has a synergistic effect with radiotherapy in animal models of this disease. In this scenario, we conducted a first-in-human phase 1 clinical trial to evaluate the safety and efficacy of intratumoral injection of Delta-24-RGD in pediatric patients with newly diagnosed DIPG prior to standard radiotherapy. The study confirmed the feasibility of this treatment with an acceptable safety profile and encouraging efficacy results. Correlative analyses showed a biological activity from Delta-24-RGD in DIPG. Further advanced trials are needed to validate these results. Meanwhile, plenty of opportunities to increase the potential contribution of oncolytic viruses in the management of devastating tumors with no current effective treatment such as DIPG need to be explored and exploited.

Oncolytic virus therapy for malignant gliomas: entering the new era

INTRODUCTION

To overcome the challenge of treating malignant brain tumors, oncolytic viruses (OVs) represent an innovative therapeutic approach, featuring unique mechanisms of action. The recent conditional approval of the oncolytic herpes simplex virus G47Δ as a therapeutic for malignant brain tumors marked a significant milestone in the long history of OV development in neuro-oncology.

AREAS COVERED

This review summarizes the results of recently completed and active clinical studies that investigate the safety and efficacy of different OV types in patients with malignant gliomas. The changing landscape of the OV trial design includes expansion of subjects to newly diagnosed tumors and pediatric populations. A variety of delivery methods and new routes of administration are vigorously tested to optimize tumor infection and overall efficacy. New therapeutic strategies such as combination with immunotherapies are proposed that take advantage of the characteristics of OV therapy as an immunotherapy. Preclinical studies of OV have been active and aim to translate new OV strategies to the clinic.

EXPERT OPINION

For the next decade, clinical trials and preclinical and translational research will continue to drive the development of innovative OV treatments for malignant gliomas and benefit patients and define new OV biomarkers.

Recent Developments in Glioblastoma Therapy: Oncolytic Viruses and Emerging Future Strategies

Glioblastoma is the most aggressive form of malignant brain tumor. Standard treatment protocols and traditional immunotherapy are poorly effective as they do not significantly increase the long-term survival of glioblastoma patients. Oncolytic viruses (OVs) may be an effective alternative approach. Combining OVs with some modern treatment options may also provide significant benefits for glioblastoma patients. Here we review virotherapy for glioblastomas and describe several OVs and their combination with other therapies. The personalized use of OVs and their combination with other treatment options would become a significant area of research aiming to develop the most effective treatment regimens for glioblastomas.

Combination therapy with oncolytic viruses and immune checkpoint inhibitors in head and neck squamous cell carcinomas: an approach of complementary advantages

Squamous cell carcinomas are the most common head and neck malignancies. Significant progress has been made in standard therapeutic methods combining surgery, radiation, and chemotherapy. Nevertheless, the 5-year survival rate remains at 40-50%. Immune checkpoint inhibitors (ICIs) are a new strategy for treating head and neck squamous cell carcinomas (HNSCCs). Still, the overall response and effective rates are poor, as HNSCCs are 'cold' tumors with an immunosuppressive tumor microenvironment (TME), limiting ICI's beneficial effects. In this case, transforming the tumor suppression microenvironment before using ICIs could be helpful. Oncolytic viruses (OVs) can transform cold tumors into hot tumors, improving the situation. Talimogene laherparepvec (T-VEC), oncolytic immunotherapy authorized for advanced melanoma, also showed good safety and antitumor activity in treating head and neck cancer and pancreatic cancer. In combination with pembrolizumab, T-Vec may have more anticancer efficacy than either drug alone. Therefore, understanding the mechanisms underpinning OVs and their potential synergism with ICIs could benefit patients with HNSCC.

The efficacy and safety of anti-PD-1/PD-L1 in treatment of glioma: a single-arm meta-analysis

Objective

This meta-analysis aimed to evaluate the efficacy and safety of PD-1/PD-L1 inhibitors in patients with glioma.

Methods

PubMed, EMBASE, Web of Science, and the Cochrane library were searched from inception to January 2023 without language restriction. Primary outcomes included overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and adverse events (AEs). The risk of bias was assessed by subgroup analysis, sensitivity analysis, and publication bias, including funnel plot, Egger's test, and Begg's test.

Results

A total of 20 studies involving 2,321 patients were included in this meta-analysis. In the analysis of the included phase III clinical trials, the forest plot showed that PD-1/PD-L1 inhibitors did not improve the OS (HR=1.15, 95% CI: 1.03-1.29, P=0.02, I² = 14%) and PFS (HR=1.43, 95% CI: 1.03-1.99, P=0.03, I² = 87%). In the single-arm analysis, the forest plot demonstrated that the 6-month OS was 71% (95% CI: 57%-83%, I² = 92%), 1-year OS was 43% (95% CI: 33%-54%, I² = 93%), and the 2-year OS was 27% (95% CI: 13%-44%, I² = 97%). The pooled estimate of the median OS was 8.85 months (95% CI: 7.33-10.36, I² = 91%). Furthermore, the result indicated that the 6-month PFS was 28% (95% CI: 18%-40%, I² = 95%), 1-year PFS was 15% (95% CI: 8%-23%, I² = 92%), and the 18-month PFS was 10% (95% CI: 3%-20%, I² = 93%). The pooled estimate of the median PFS was 3.72 months (95% CI: 2.44-5.00, I² = 99%). For ORR, the pooled estimate of ORR was 10% (95% CI: 2%-20%, I² = 88%). We further analyzed the incidence of PD-1/PD-L1 inhibitor-related AEs, and the pooled incidence of AEs was 70% (95% CI: 58%-81%, I² = 94%). The incidence of AEs ≥ grade 3 was 19% (95% CI: 11%-30%, I² = 94%). The funnel plot for the median PFS and median OS was symmetric with no significant differences in Egger's test and Begg's test. The sensitivity analysis revealed that our results were stable and reliable.

Conclusion

The results of this meta-analysis suggest that anti-PD-1/PD-L1 therapy is relatively safe but could not prolong survival in glioma. More randomized controlled trials are needed to confirm our results.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023396057.

The integrative analysis based on super-enhancer related genes for predicting different subtypes and prognosis of patient with lower-grade glioma

Objective: Emerging evidence revealed that super-enhancer plays a crucial role in the transcriptional reprogramming for many cancers. The purpose aimed to explored how the super-enhancer related genes affects the prognosis and tumor immune microenvironment (TIME) of patients with low-grade glioma (LGG). Methods: In this study, the differentially expressed genes (DEGs) between LGG cohorts and normal brain tissue cohort were identified by the comprehensive analysis of the super-enhancer (SE) related genes. Then non-negative matrix factorization was performed to seek the optimal classification based on the DEGs, while investigating prognostic and clinical differences between different subtypes. Subsequently, a prognostic related signature (SERS) was constructed for the comprehensive evaluation in term of individualized prognosis, clinical characteristics, cancer markers, genomic alterations, and immune microenvironment of patients with LGG. Results: Based on the expression profiles of 170 DEGs, we identified three SE subtypes, and the three subtypes showed significant differences in prognostic, clinicopathological features. Then, nine optimal SE-related genes were selected to construct the SERS through the least absolute shrinkage and selection operator Cox regression analysis. Survival analysis showed that SERS had strong and stable predictive ability for the prognosis of LGG patients in the The Cancer Genome Atlas, China Glioma Genome Atlas, and Remdrandt cohorts, respectively. We also found that SERS was highly correlated with clinicopathological features, tumor immune microenvironment, cancer hallmarks, and genomic alterations in LGG patients. In addition, the predictive power of SERS for immune checkpoint inhibitor treatment is also superior. The qRT-PCR results and immunohistochemical results also confirmed the difference in the expression of four key genes in normal cells and tumors, as well as in normal tissues and tumor tissues. Conclusion: The SERS could be suitable to utilize individualized prognosis prediction and immunotherapy options for LGG patients in clinical application.

The Oncolytic Adenovirus XVir-N-31, in Combination with the Blockade of the PD-1/PD-L1 Axis, Conveys Abscopal Effects in a Humanized Glioblastoma Mouse Model

Glioblastoma (GBM) is an obligatory lethal brain tumor with a median survival, even with the best standard of care therapy, of less than 20 months. In light of this fact, the evaluation of new GBM treatment approaches such as oncolytic virotherapy (OVT) is urgently needed. Based on our preliminary preclinical data, the YB-1 dependent oncolytic adenovirus (OAV) XVir-N-31 represents a promising therapeutic agent to treat, in particular, therapy resistant GBM. Preclinical studies have shown that XVir-N-31 prolonged the survival of GBM bearing mice. Now using an immunohumanized mouse model, we examined the immunostimulatory effects of XVir-N-31 in comparison to the wildtype adenovirus (Ad-WT). Additionally, we combined OVT with the inhibition of immune checkpoint proteins by using XVir-N-31 in combination with nivolumab, or by using a derivate of XVir-N-31 that expresses a PD-L1 neutralizing antibody. Although in vitro cell killing was higher for Ad-WT, XVir-N-31 induced a much stronger immunogenic cell death that was further elevated by blocking PD-1 or PD-L1. In vivo, an intratumoral injection of XVir-N-31 increased tumor infiltrating lymphocytes (TILs) and NK cells significantly more than Ad-WT not only in the virus-injected tumors, but also in the untreated tumors growing in the contralateral hemisphere. This suggests that for an effective treatment of GBM, immune activating properties by OAVs seem to be of greater importance than their oncolytic capacity. Furthermore, the addition of immune checkpoint inhibition (ICI) to OVT further induced lymphocyte infiltration. Consequently, a significant reduction in contralateral non-virus-injected tumors was only visible if OVT was combined with ICI. This strongly indicates that for an effective eradication of GBM cells that cannot be directly targeted by an intratumoral OV injection, additional ICI therapy is required.

Immunology Meets Bioengineering: Improving the Effectiveness of Glioblastoma Immunotherapy

Glioblastoma (GBM) therapy has seen little change over the past two decades. Surgical excision followed by radiation and chemotherapy is the current gold standard treatment. Immunotherapy techniques have recently transformed many cancer treatments, and GBM is now at the forefront of immunotherapy research. GBM immunotherapy prospects are reviewed here, with an emphasis on immune checkpoint inhibitors and oncolytic viruses. Various forms of nanomaterials to enhance immunotherapy effectiveness are also discussed. For GBM treatment and immunotherapy, we outline the specific properties of nanomaterials. In addition, we provide a short overview of several 3D (bio)printing techniques and their applications in stimulating the GBM microenvironment. Lastly, the susceptibility of GBM cancer cells to the various immunotherapy methods will be addressed.

Transcriptome Analysis and Single-Cell Sequencing Analysis Constructed the Ubiquitination-Related Signature in Glioma and Identified USP4 as a Novel Biomarker

Background

Glioma, the most frequent malignant tumor of the neurological system, has a poor prognosis and treatment problems. Glioma's tumor microenvironment is also little known.

Methods

We downloaded glioma data from the TCGA database. The patients in the TCGA database were split into two groups, one for training and the other for validation. The ubiquitination genes were then evaluated in glioma using COX and Lasso regression to create a ubiquitination-related signature. We assessed the signature's predictive usefulness and role in the immune microenvironment after it was generated. Finally, in vitro experiment were utilized to check the expression and function of the signature's key gene, USP4.

Results

This signature can be used to categorize glioma patients. Glioma patients can be separated into high-risk and low-risk groups in both the training and validation cohorts, with the high-risk group having a significantly worse prognosis (P<0.05). Following further investigation of the immune microenvironment, it was discovered that this risk grouping could serve as a guide for glioma immunotherapy. The activity, invasion and migration capacity, and colony formation ability of U87-MG and LN229 cell lines were drastically reduced after the important gene USP4 in signature was knocked down in cell tests. Overexpression of USP4 in the A172 cell line, on the other hand, greatly improved clonogenesis, activity, invasion and migration.

Conclusions

Our research established a foundation for understanding the role of ubiquitination genes in gliomas and identified USP4 as a possible glioma biomarker.

Oncogenic magnesium transporter 1 upregulates programmed death-1-ligand 1 expression and contributes to growth and radioresistance of glioma cells through the ERK/MAPK signaling pathway

Radiotherapy has been established as a major therapeutic modality for glioma, whereas new therapeutic targets are needed to prevent tumor recurrence. This study intends to explore the regulatory role of magnesium transporter 1 (MAGT1) in radiotherapy resistance of glioma through modulating ERK and programmed death-1-ligand 1 (PD-L1). Our bioinformatics analysis identified differentially expressed MAGT1 in glioma, expression of which was subsequently determined in cohort data of TCGA database and microarray dataset as well as glioma cell lines. Artificial modulation of MAGT1, ERK, and PD-L1 expression was performed to examine their effects on glioma cell proliferation and radioresistance, as reflected by MTT and colony formation assays under irradiation. Mouse glioma cells with manipulated MAGT1 and ERK inhibitors were further injected into mice to assess the in vivo tumor formation ability of glioma cells. It was noted that MAGT1 expression was highly expressed in glioma tissues of TCGA data and microarray dataset, which was then validated in glioma cell lines. Ectopic expression of MAGT1 was revealed to promote the proliferation and radioresistance of glioma cells, which was attributed to the MAGT1-mediated activation of the ERK/MAPK signaling pathway. It was illuminated that MAGT1 stimulated PD-L1 expression through the ERK/MAPK pathway and thus facilitated glioma cell growth. Additionally, MAGT1 overexpression accelerated the in vivo tumor formation of glioma cells, while the ERK inhibitor negated its effect. In conclusion, MAGT1 enhances the growth and radioresistance of glioma cells through the ERK/MAPK signaling pathway-mediated upregulation of PD-L1 expression.

Exploiting 4-1BB immune checkpoint to enhance the efficacy of oncolytic virotherapy for diffuse intrinsic pontine gliomas

Diffuse intrinsic pontine gliomas (DIPGs) are aggressive pediatric brain tumors, and patient survival has not changed despite many therapeutic efforts, emphasizing the urgent need for effective treatments. Here, we evaluated the anti-DIPG effect of the oncolytic adenovirus Delta-24-ACT, which was engineered to express the costimulatory ligand 4-1BBL to potentiate the antitumor immune response of the virus. Delta-24-ACT induced the expression of functional 4-1BBL on the membranes of infected DIPG cells, which enhanced the costimulation of CD8⁺ T lymphocytes. In vivo, Delta-24-ACT treatment of murine DIPG orthotopic tumors significantly improved the survival of treated mice, leading to long-term survivors that developed immunological memory against these tumors. In addition, Delta-24-ACT was safe and caused no local or systemic toxicity. Mechanistic studies showed that Delta-24-ACT modulated the tumor-immune content, not only increasing the number, but also improving the functionality of immune cells. All of these data highlight the safety and potential therapeutic benefit of Delta-24-ACT the treatment of patients with DIPG.

Establishing Imaging Biomarkers of Host Immune System Efficacy during Glioblastoma Therapy Response: Challenges, Obstacles and Future Perspectives

This hypothesis proposal addresses three major questions: (1) Why do we need imaging biomarkers for assessing the efficacy of immune system participation in glioblastoma therapy response? (2) Why are they not available yet? and (3) How can we produce them? We summarize the literature data supporting the claim that the immune system is behind the efficacy of most successful glioblastoma therapies but, unfortunately, there are no current short-term imaging biomarkers of its activity. We also discuss how using an immunocompetent murine model of glioblastoma, allowing the cure of mice and the generation of immune memory, provides a suitable framework for glioblastoma therapy response biomarker studies. Both magnetic resonance imaging and magnetic resonance-based metabolomic data (i.e., magnetic resonance spectroscopic imaging) can provide non-invasive assessments of such a system. A predictor based in nosological images, generated from magnetic resonance spectroscopic imaging analyses and their oscillatory patterns, should be translational to clinics. We also review hurdles that may explain why such an oscillatory biomarker was not reported in previous imaging glioblastoma work. Single shot explorations that neglect short-term oscillatory behavior derived from immune system attack on tumors may mislead actual response extent detection. Finally, we consider improvements required to properly predict immune system-mediated early response (1–2 weeks) to therapy. The sensible use of improved biomarkers may enable translatable evidence-based therapeutic protocols, with the possibility of extending preclinical results to human patients.

Superior infectivity of the fiber chimeric oncolytic adenoviruses Ad5/35 and Ad5/3 over Ad5-delta-24-RGD in primary glioma cultures

Ad5-delta-24-RGD is currently the most clinically advanced recombinant adenovirus (rAd) for glioma therapy. We constructed a panel of fiber-modified rAds (Ad5RGD, Ad5/3, Ad5/35, Ad5/3RGD, and Ad5/35RGD, all harboring the delta-24 modification) and compared their infectivity, replication, reproduction, and cytolytic efficacy in human and rodent glioma cell lines and short-term cultures from primary gliomas. In human cells, both Ad5/35-delta-24 and Ad5/3-delta-24 displayed superior infectivity and cytolytic efficacy over Ad5-delta-24-RGD, while Ad5/3-delta-24-RGD and Ad5/35-delta-24-RGD did not show further improvements in efficacy. The expression of the adenoviral receptors/coreceptors CAR, DSG2, and CD46 and the integrins αVβ3/αVβ5 did not predict the relative cytolytic efficacy of the fiber-modified rAds. The cytotoxicity of the fiber-modified rAds in human primary normal cultures of different origins and in primary glioma cultures was comparable, indicating that the delta-24 modification did not confer tumor cell selectivity. We also revealed that CT-2A and GL261 glioma cells might be used as murine cell models for the fiber chimeric rAds in vitro and in vivo. In GL261 tumor-bearing mice, Ad5/35-delta-24, armed with the immune costimulator OX40L as the E2A/DBP-p2A-mOX40L fusion, produced long-term survivors, which were able to reject tumor cells upon rechallenge. Our data underscore the potential of local Ad5/35-delta-24-based immunovirotherapy for glioblastoma treatment.

Local treatment of a pediatric osteosarcoma model with a 4-1BBL armed oncolytic adenovirus results in an antitumor effect and leads to immune memory

Osteosarcoma is an aggressive bone tumor occurring primarily in pediatric patients. Despite years of intensive research, the outcomes of patients with metastatic disease or who do not respond to therapy have remained poor and have not changed in the last 30 years. Oncolytic virotherapy is becoming a reality to treat local and metastatic tumors while maintaining a favorable safety profile. Delta-24-ACT is a replicative oncolytic adenovirus engineered to selectively target cancer cells and to potentiate immune responses through expression of the immune costimulatory ligand 4-1BB. This work aimed to assess the antisarcoma effect of Delta-24-ACT. MTS and replication assays were used to quantify the antitumor effects of Delta-24-ACT in vitro in osteosarcoma human and murine cell lines. Evaluation of the in vivo antitumor effect and immune response to Delta-24-ACT was performed in immunocompetent mice bearing orthotopic K7M2 cell line. Immunophenotyping of the tumor microenvironment was characterized by immunohistochemistry and flow cytometry. In vitro, Delta-24-ACT killed osteosarcoma cells and triggered the production of danger signals. In vivo, local treatment with Delta-24-ACT led to antitumor effects against both the primary tumor and spontaneous metastases in a murine osteosarcoma model. Viral treatment was safe, with no noted toxicity. Delta-24-ACT significantly increased the median survival time of treated mice. Collectively, our data identify Delta-24-ACT administration as an effective and safe therapeutic strategy for local and metastatic osteosarcoma. These results support clinical translation of this viral immunotherapy approach.

Oncolytic ImmunoViroTherapy: A long history of crosstalk between viruses and immune system for cancer treatment

Cancer Immunotherapy relies on harnessing a patient's immune system to fine-tune specific anti-tumor responses and ultimately eradicate cancer. Among diverse therapeutic approaches, oncolytic viruses (OVs) have emerged as a novel form of cancer immunotherapy. OVs are a naturally occurring or genetically modified class of viruses able to selectively kill cancer cells, leaving healthy cells unharmed; in the last two decades, the role of OVs has been redefined to act beyond their oncolytic activity. Indeed, the immunogenic cancer cell death mediated by OVs induces the release of tumor antigens that in turn induces anti-tumor immunity, allowing OVs to act as in situ therapeutic cancer vaccines. Additionally, OVs can be engineered for intratumoral delivery of immunostimulatory molecules such as tumor antigens or cytokines to further enhance anti-tumor response. Moreover, OVs can be used in combination with other cancer immunotherapeutic approaches such as Immune Checkpoint Inhibitors and CAR-T cells. The current review first defines the three main mechanisms of action (MOA) of OVs currently used in cancer therapy that are: i) Oncolysis, ii) OV-induced cancer-specific immune activation, and iii) Exploiting pre-existing anti-viral immunity to enhance cancer therapy. Secondly, we focus on how OVs can induce and/or improve anti-cancer immunity in a specific or unspecific fashion, highlighting the importance of these approaches. Finally, the last part of the review analyses OVs combined with other cancer immunotherapies, revising present and future clinical applications.