Oncolytic virus expressing PD-1 inhibitors activates a collaborative intratumoral immune response to control tumor and synergizes with CTLA-4 or TIM-3 blockade

Neospora caninum as delivery vehicle for anti-PD-L1 scFv-Fc: A novel approach for cancer immunotherapy

Neospora caninum, a potential anticancer agent able to reactivate the immune response within the tumor microenvironment (TME), has recently shown enhanced immunomodulatory properties in different tumor models when armed with the cytokine, Il-15. In the current area of combination immunotherapy strategies designed to overcome treatment resistance, we engineered for the first time the protozoan Neospora caninum to vectorize and secrete a single-chain variable fragment fused to fragment crystallizable region (scFv-Fc) targeting human programmed cell death ligand 1 (PD-L1). Following validation of its secretion through the micronemes (protozoa secretory organelles), we demonstrated that the scFv-Fc could bind PD-L1 on mouse and human tumor cells, block the programmed cell death protein 1 (PD-1)/PD-L1 pathway leading to potentiate the T cell lymphocyte activity. Additionally, the scFv-Fc induced antibody-dependent cellular phagocytosis (ADCP) and antibody-dependent cellular cytotoxicity (ADCC). Those data demonstrate the feasibility of vectoring and secreting a functional antibody fragment by N. caninum, opening promising avenues for future research.

Synergistic targeting strategies for prostate cancer

Prostate cancer is the second most commonly diagnosed cancer and the fifth leading cause of death among men worldwide. Androgen deprivation therapy is a common prostate cancer treatment, but its efficacy is often hindered by the development of resistance, which results in reducing survival benefits. Immunotherapy showed great promise in treating solid tumours; however, clinically significant improvements have not been demonstrated for patients with prostate cancer, highlighting specific drawbacks of this therapeutic modality. Hence, exploring novel strategies to synergistically enhance the efficacy of prostate cancer immunotherapy is imperative. Clinical investigations have focused on the combined use of targeted or gene therapy and immunotherapy for prostate cancer. Notably, tumour-specific antigens and inflammatory mediators are released from tumour cells after targeted or gene therapy, and the recruitment and infiltration of immune cells, including CD8+ T cells and natural killer cells activated by immunotherapy, are further augmented, markedly improving the efficacy and prognosis of prostate cancer. Thus, immunotherapy, targeted therapy and gene therapy could have reciprocal synergistic effects in prostate cancer in combination, resulting in a proposed synergistic model encompassing these three therapeutic modalities, presenting novel potential treatment strategies for prostate cancer.

Generalization of neoantigen-based tumor vaccine by delivering peptide-MHC complex via oncolytic virus

Neoantigen vaccine is a promising breakthrough in tumor immunotherapy. However, the application of this highly personalized strategy in the treatment of solid tumors is hindered by several obstacles, including very costly and time-consuming preparation steps, uncertainty in prediction algorithms and tumor heterogeneity. Universalization of neoantigen vaccine is an ideal yet currently unattainable solution to such limitations. To overcome these limitations, we engineered oncolytic viruses co-expressing neoantigens and neoantigen-binding major histocompatibility complex (MHC) molecules to force ectopic delivery of peptide-MHC ligands to T cell receptors (TCRs), enabling specific targeting by neoantigen vaccine-primed host immunity. When integrated with neoantigen vaccination, the engineered viruses exhibited potent cytolytic activity in a variety of tumor models irrespective of the neoantigen expression profiles, eliciting robust systemic antitumor immunity to reject tumor rechallenge and inhibit abscopal tumor growth with a favorable safety profile. Thus, this study provides a powerful approach to enhance the universality and efficacy of neoantigen vaccines, meeting the urgent need for universal neoantigen vaccines in the clinic to facilitate the further development of tumor immunotherapy.

Oncolytic viruses: a promising therapy for malignant pleural effusion and solid tumors

Oncolytic viruses (OVs) are natural or recombinant viruses that can directly lyse tumor cells without damaging normal cells. They enhance anti-tumor immunity by releasing antigens and activating inflammatory responses within the tumor microenvironment (TME). This offers a new therapeutic approach for MPE and solid tumors. This review discusses the progress of OVs administered via intrapleural and intratumoral routes, emphasizing their potential in MPE treatment and the challenges posed by the complex intrapleural environment, which affects the direct interaction between OVs, tumor cells, and immune cells. This review also discusses the regulatory barriers, safety concerns and accessibility of oncolytic virus therapy.

Combinational therapeutic strategies to overcome resistance to immune checkpoint inhibitors

Over the past few years, immune checkpoint inhibitors resulted in magnificent and durable successes in treating cancer; however, only a minority of patients respond favorably to the treatment due to a broad-spectrum of tumor-intrinsic and tumor-extrinsic factors. With the recent insights gained into the mechanisms of resistance, combination treatment strategies to overcome the resistance and enhance the therapeutic potential of immune checkpoint inhibitors are emerging and showing promising results in both pre-clinical and clinical settings. This has been derived through multiple interconnected mechanisms such as enhancing tumor immunogenicity, improving neoantigen processing and presentation in addition to augmenting T cell infiltration and cytotoxic potentials. In the clinical settings, several avenues of combination treatments involving immune checkpoint inhibitors were associated with considerable improvement in the therapeutic outcome in terms of patient's survival and tumor growth control. This, in turn, increased the spectrum of cancer patients benefiting from the unprecedented and durable effects of immune checkpoint inhibitors leading to their adoption as a first-line treatment for certain cancers. Moreover, the significance of precision medicine in cancer immunotherapy and the unmet demand to develop more personalized predictive biomarkers and treatment strategies are also highlighted in this review.

Combination therapy with oncolytic viruses for lung cancer treatment

Lung cancer is the leading cause of cancer-related death globally. Despite various treatment options, adverse reactions and treatment resistance limit their clinical application and efficacy, therefore, new effective treatment options are still needed. Oncolytic viruses (OVs) are a new anti-cancer option. With a powerful anti-tumor effect, OVs are gradually being applied to the treatment of solid tumor. In clinical practice, we have found that in patients with NSCLC and SCLC, OVs combined with immune checkpoint inhibitors (ICI) treatment make tumor with poor response to immunotherapy become sensitive. Furthermore, studies have shown that OVs combined with chemotherapy, radiation therapy, and other immune approaches (such as anti-pd1 drugs) have synergistic effects. These studies suggest that OVs combined therapy may bring hope for the treatment of lung cancer patients. This article will review the current status and prospect of OVs combination therapy in the field of lung cancer treatment and summarizes the mechanism of action.

Comprehensive Analysis of GPSM2: From Pan-Cancer Analysis to Experimental Validation

G-protein signalling modulator 2 (GPSM2) plays an important role in maintaining cell polarisation and regulating the cell cycle; however, a systematic and comprehensive analysis of GPSM2 in cancer is still lacking. Using extensive multi-omics data, we explored the pan-cancer expression levels of GPSM2 from multiple perspectives and its association with prognosis, diagnosis, tumour stemness, immune-related genes, immune cell infiltration, genomic instability, and response to immunotherapy. We also elucidated the potential pan-cancer biological functions of GPSM2 using gene set enrichment analysis (GSEA) and searched for targeted drugs that affect GPSM2 expression using connectivity map analysis. To elucidate the effect of GPSM2 on colon cancer, we evaluated its effect on the biological behaviour of two colon cancer cell lines. In this study, GPSM2 was systematically analysed and shown to have satisfactory performance in disease diagnosis and prognostic prediction of various cancers. G-protein signalling modulator 2 plays an important role in the genesis and development of various tumours and is a potential tumour diagnostic and prognostic biomarker as well as an anti-cancer therapeutic target.

Advanced progress in the genetic modification of the oncolytic HSV-1 virus

The use of replication-competent viruses for selective tumor oncolysis while sparing normal cells marks a significant advancement in cancer treatment. HSV-1 presents several advantages that position it as a leading candidate for oncolytic virotherapies. Its large genome can accommodate insertions over 30 kb or deletions of multiple virulence genes without compromising lytic replication in tumor cells. Additionally, anti-herpes drugs can inhibit its replication during accidental infections. Importantly, HSV-1 does not integrate into the host genome and cause mutations. The HSV-1 genome can be modified through genetic engineering in two main ways: first, by reducing infectivity and toxicity to normal cells via limited replication and assembly, altered protein-virus receptor binding, and minimized immune evasion; second, by enhancing anticancer activity through disruption of tumor cell metabolism, induction of autophagy, improved immune recognition, and modification of the tumor microenvironment. In this mini-review, we systematically examine genetic modification strategies for oncolytic HSV-1 while highlighting advancements from these modifications. Certain genetic alterations have shown efficacy in improving clinical outcomes for HSV-1-based therapies. These modifications include silencing specific genes and inserting exogenous genes into the HSV-1 genome. The insertion of exogenous genes has increasingly been used to develop new oncolytic HSV-1 variants. Finally, we discuss limitations associated with oncolytic virotherapy at the conclusion of this review. As more clinical trials explore newly engineered therapies, they are likely to yield breakthroughs and promote broader adoption for cancer treatment.

Vaccinia virus-mediated oncolytic immunotherapy: Emerging strategies for gastrointestinal cancer treatment at dawn

Oncolytic vaccinia virus (VVs) based immunotherapy is a rapidly developing treatment for gastrointestinal (GI) cancers. Conventional treatments, such as chemotherapy, radiotherapy and surgery achieve good effects in early-stage GI cancers, but effects are limited in advanced disease. Immunotherapy has limited efficacy in GI cancers due to tumor heterogeneity and complex immunosuppressive mechanisms. Oncolytic VV immunotherapy is a novel treatment approach showing promising results in preclinical and clinical trials. Oncolytic VV's intracytoplasmic replication and assembly mechanism, diverse mature forms, and use methods make it extremely safe and versatile for drug delivery. Combining oncolytic VV with conventional therapies and immunotherapy (e.g., ICIs, CAR-T) enhances tumor regression and survival compared to monotherapies. Researchers are establishing response protocols and improvement strategies, rapidly developing VV tumor oncolytic immunotherapy. This article focuses on oncolytic vaccinia development and outlook in gastrointestinal cancer therapy, advantages when combined with other drugs to improve clinical survival, safety, and risk reduction for patients.

A comprehensive review of immune checkpoint inhibitors for cancer treatment

Immunology-based therapies are emerging as an effective cancer treatment, using the body's immune system to target tumors. Immune checkpoints, which regulate immune responses to prevent tissue damage and autoimmunity, are often exploited by cancer cells to avoid destruction. The discovery of checkpoint proteins like PD-1/PD-L1 and CTLA-4 was pivotal in developing cancer immunotherapy. Immune checkpoint inhibitors (ICIs) have shown great success, with FDA-approved drugs like PD-1 inhibitors (Nivolumab, Pembrolizumab, Cemiplimab), PD-L1 inhibitors (Atezolizumab, Durvalumab, Avelumab), and CTLA-4 inhibitors (Ipilimumab, Tremelimumab), alongside LAG-3 inhibitor Relatlimab. Research continues on new checkpoints like TIM-3, VISTA, B7-H3, BTLA, and TIGIT. Biomarkers like PDL-1 expression, tumor mutation burden, interferon-γ presence, microbiome composition, and extracellular matrix characteristics play a crucial role in predicting responses to immunotherapy with checkpoint inhibitors. Despite their effectiveness, not all patients experience the same level of benefit, and organ-specific immune-related adverse events (irAEs) such as rash or itching, colitis, diarrhea, hyperthyroidism, and hypothyroidism may occur. Given the rapid advancements in this field and the variability in patient outcomes, there is an urgent need for a comprehensive review that consolidates the latest findings on immune checkpoint inhibitors, covering their clinical status, biomarkers, resistance mechanisms, strategies to overcome resistance, and associated adverse effects. This review aims to fill this gap by providing an analysis of the current clinical status of ICIs, emerging biomarkers, mechanisms of resistance, strategies to enhance therapeutic efficacy, and assessment of adverse effects. This review is crucial to furthering our understanding of ICIs and optimizing their application in cancer therapy.

Advancements of engineered live oncolytic biotherapeutics (microbe/virus/cells): Preclinical research and clinical progress

The proven efficacy of immunotherapy in fighting tumors has been firmly established, heralding a new era in harnessing both the innate and adaptive immune systems for cancer treatment. Despite its promise, challenges such as inefficient delivery, insufficient tumor penetration, and considerable potential toxicity of immunomodulatory agents have impeded the advancement of immunotherapies. Recent endeavors in the realm of tumor prophylaxis and management have highlighted the use of living biological entities, including bacteria, oncolytic viruses, and immune cells, as a vanguard for an innovative class of live biotherapeutic products (LBPs). These LBPs are gaining recognition for their inherent ability to target tumors. However, these LBPs must contend with significant barriers, including robust immune clearance mechanisms, cytotoxicity and other in vivo adverse effects. Priority must be placed on enhancing their safety and therapeutic indices. This review consolidates the latest preclinical research and clinical progress pertaining to the exploitation of engineered biologics, spanning bacteria, oncolytic viruses, immune cells, and summarizes their integration with combination therapies aimed at circumventing current clinical impasses. Additionally, the prospective utilities and inherent challenges of the biotherapeutics are deliberated, with the objective of accelerating their clinical application in the foreseeable future.

Nanoengineering-armed oncolytic viruses drive antitumor response: progress and challenges

Oncolytic viruses (OVs) have emerged as a powerful tool in cancer therapy. Characterized with the unique abilities to selectively target and lyse tumor cells, OVs can expedite the induction of cell death, thereby facilitating effective tumor eradication. Nanoengineering-derived OVs overcome traditional OV therapy limitations by enhancing the stability of viral circulation, and tumor targeting, promising improved clinical safety and efficacy and so on. This review provides a comprehensive analysis of the multifaceted mechanisms through which engineered OVs can suppress tumor progression. It initiates with a concise delineation on the fundamental attributes of existing OVs, followed by the exploration of their mechanisms of the antitumor response. Amid rapid advancements in nanomedicine, this review presents an extensive overview of the latest developments in the synergy between nanomaterials, nanotechnologies, and OVs, highlighting the unique characteristics and properties of the nanomaterials employed and their potential to spur innovation in novel virus design. Additionally, it delves into the current challenges in this emerging field and proposes strategies to overcome these obstacles, aiming to spur innovation in the design and application of next-generation OVs.

Progression of oncolytic virus in liver cancer treatment

The liver plays a crucrial role in detoxification, metabolism, and nutrient storage. Because liver cancer ranks among the top three leading causes of death globally, there is an urgent need for developing treatment strategies for liver cancer. Although traditional approaches such as radiation, chemotherapy, surgical removal, and transplantation are widely practiced, the number of patients with liver cancer continues to increase rapidly each year. Some novel therapeutics for liver cancer have been studied for many years. In the past decade, oncolytic therapy has emerged, in which viruses selectively infect and destroy cancer cells while sparing normal cells. However, oncolytic virotherapy for liver cancer remains relatively obscure due to the aggressive nature of the disease and the limited effectiveness of treatment. To keep pace with the latest developments in oncolytic tumor therapy for liver cancer, this review summarizes basic science studies and clinical trials conducted within 5 years, focusing on the efficacy and safety profiles of the five most commonly used oncolytic viruses: herpes simplex virus, adenovirus, influenza virus, vaccinia virus, and coxsackievirus.

CD8+ T cell exhaustion and its regulatory mechanisms in the tumor microenvironment: key to the success of immunotherapy

A steady dysfunctional state caused by chronic antigen stimulation in the tumor microenvironment (TME) is known as CD8+ T cell exhaustion. Exhausted-like CD8+ T cells (CD8+ Tex) displayed decreased effector and proliferative capabilities, elevated co-inhibitory receptor generation, decreased cytotoxicity, and changes in metabolism and transcription. TME induces T cell exhaustion through long-term antigen stimulation, upregulation of immune checkpoints, recruitment of immunosuppressive cells, and secretion of immunosuppressive cytokines. CD8+ Tex may be both the reflection of cancer progression and the reason for poor cancer control. The successful outcome of the current cancer immunotherapies, which include immune checkpoint blockade and adoptive cell treatment, depends on CD8+ Tex. In this review, we are interested in the intercellular signaling network of immune cells interacting with CD8+ Tex. These findings provide a unique and detailed perspective, which is helpful in changing this completely unpopular state of hypofunction and intensifying the effect of immunotherapy.

Emerging roles of intratumor microbiota in cancer: tumorigenesis and management strategies

The intricate interplay between the host and its microbiota has garnered increasing attention in the past decade. Specifically, the emerging recognition of microorganisms within diverse cancer tissues, previously presumed sterile, has ignited a resurgence of enthusiasm and research endeavors. Four potential migratory routes have been identified as the sources of intratumoral microbial "dark matter," including direct invasion of mucosal barriers, spreading from normal adjacent tissue, hematogenous spread, and lymphatic drainage, which contribute to the highly heterogeneous features of intratumor microbiota. Importantly, multitudes of studies delineated the roles of intratumor microbiota in cancer initiation and progression, elucidating underlying mechanisms such as genetic alterations, epigenetic modifications, immune dysfunctions, activating oncogenic pathways, and inducing metastasis. With the deepening understanding of intratumoral microbial composition, novel microbiota-based strategies for early cancer diagnosis and prognostic stratification continue to emerge. Furthermore, intratumor microbiota exerts significant influence on the efficacy of cancer therapeutics, particularly immunotherapy, making it an enticing target for intervention in cancer treatment. In this review, we present a comprehensive discussion of the current understanding pertaining to the developmental history, heterogeneous profiles, underlying originations, and carcinogenic mechanisms of intratumor microbiota, and uncover its potential predictive and intervention values, as well as several inevitable challenges as a target for personalized cancer management strategies.

T cell exhaustion in human cancers

T cell exhaustion refers to a progressive state in which T cells become functionally impaired due to sustained antigenic stimulation, which is characterized by increased expression of immune inhibitory receptors, but weakened effector functions, reduced self-renewal capacity, altered epigenetics, transcriptional programme and metabolism. T cell exhaustion is one of the major causes leading to immune escape of cancer, creating an environment that supports tumor development and metastatic spread. In addition, T cell exhaustion plays a pivotal role to the efficacy of current immunotherapies for cancer. This review aims to provide a comprehensive view of roles of T cell exhaustion in cancer development and progression. We summerized the regulatory mechanisms that involved in T cell exhaustion, including transcription factors, epigenetic and metabolic reprogramming events, and various microenvironmental factors such as cytokines, microorganisms, and tumor autocrine substances. The paper also discussed the challenges posed by T cell exhaustion to cancer immunotherapies, including immune checkpoint blockade (ICB) therapies and chimeric antigen receptor T cell (CAR-T) therapy, highlightsing the obstacles encountered in ICB therapies and CAR-T therapies due to T cell exhaustion. Finally, the article provides an overview of current therapeutic options aimed to reversing or alleviating T cell exhaustion in ICB and CAR-T therapies. These therapeutic approaches seek to overcome T cell exhaustion and enhance the effectiveness of immunotherapies in treating tumors.

Tutorial: design, production and testing of oncolytic viruses for cancer immunotherapy

Oncolytic viruses (OVs) represent a novel class of cancer immunotherapy agents that preferentially infect and kill cancer cells and promote protective antitumor immunity. Furthermore, OVs can be used in combination with established or upcoming immunotherapeutic agents, especially immune checkpoint inhibitors, to efficiently target a wide range of malignancies. The development of OV-based therapy involves three major steps before clinical evaluation: design, production and preclinical testing. OVs can be designed as natural or engineered strains and subsequently selected for their ability to kill a broad spectrum of cancer cells rather than normal, healthy cells. OV selection is further influenced by multiple factors, such as the availability of a specific viral platform, cancer cell permissivity, the need for genetic engineering to render the virus non-pathogenic and/or more effective and logistical considerations around the use of OVs within the laboratory or clinical setting. Selected OVs are then produced and tested for their anticancer potential by using syngeneic, xenograft or humanized preclinical models wherein immunocompromised and immunocompetent setups are used to elucidate their direct oncolytic ability as well as indirect immunotherapeutic potential in vivo. Finally, OVs demonstrating the desired anticancer potential progress toward translation in patients with cancer. This tutorial provides guidelines for the design, production and preclinical testing of OVs, emphasizing considerations specific to OV technology that determine their clinical utility as cancer immunotherapy agents.

oHSV2-mGM repolarizes TAMs and cooperates with αPD1 to reprogram the immune microenvironment of residual cancer after radiofrequency ablation

BACKGROUND

Due to the size and location of the tumor, incomplete radiofrequency ablation (iRFA) of the target tumor inhibits tumor immunity. In this study, a murine herpes simplex virus (oHSV2-mGM) armed with granulocyte-macrophage colony-stimulating factor (GM-CSF) was constructed to explore its effect on innate and adaptive immunity during iRFA, and the inhibitory effect of programmed cell death-1 (PD1) on tumor.

METHODS

We verified the polarization and activation of RAW264.7 cells mediated by oHSV2-mGM in vitro. Subsequently, we evaluated the efficacy of oHSV2-mGM alone and in combination with αPD1 in the treatment of residual tumors after iRFA in two mouse models. RNA-seq was used to characterize the changes of tumor microenvironment.

RESULTS

oHSV2-mGM lysate effectively stimulated RAW264.7 cells to polarize into M1 cells and activated M1 phenotypic function. In the macrophage clearance experiment, oHSV2-mGM activated the immune response of tumor in mice. The results in vivo showed that oHSV2-mGM showed better anti-tumor effect in several mouse tumor models. Finally, oHSV2-mGM combined with PD1 antibody can further enhance the anti-tumor effect of oHSV2-mGM and improve the complete remission rate of tumor in mice.

CONCLUSION

The application of oHSV2-mGM leads to the profound remodeling of the immune microenvironment of residual tumors. oHSV2-mGM also works in synergy with PD1 antibody to achieve complete remission of tumors that do not respond well to monotherapy at immune checkpoints. Our results support the feasibility of recombinant oncolytic virus in the treatment of residual tumors after iRFA, and propose a new strategy for oncolytic virus treatment of tumors.

T cell exhaustion and senescence for ovarian cancer immunotherapy

Ovarian cancer is a common gynecological malignancy, and its treatment remains challenging. Although ovarian cancer may respond to immunotherapy because of endogenous immunity at the molecular or T cell level, immunotherapy has so far not had the desired effect. The functional status of preexisting T cells is an indispensable determinant of powerful antitumor immunity and immunotherapy. T cell exhaustion and senescence are two crucial states of T cell dysfunction, which share some overlapping phenotypic and functional features, but each status possesses unique molecular and developmental signatures. It has been widely accepted that exhaustion and senescence of T cells are important strategies for cancer cells to evade immunosurveillance and maintain the immunosuppressive microenvironment. Herein, this review summarizes the phenotypic and functional features of exhaust and senescent T cells, and describes the key drivers of the two T cell dysfunctional states in the tumor microenvironment and their functional roles in ovarian cancer. Furthermore, we present a summary of the molecular machinery and signaling pathways governing T cell exhaustion and senescence. Possible strategies that can prevent and/or reverse T cell dysfunction are also explored. An in-depth understanding of exhausted and senescent T cells will provide novel strategies to enhance immunotherapy of ovarian cancer through redirecting tumor-specific T cells away from a dysfunctional developmental trajectory.

Enhanced Anti-Tumor Response Elicited by a Novel Oncolytic Pseudorabies Virus Engineered with a PD-L1 Inhibitor

Oncolytic viruses combined with immunotherapy offer significant potential in tumor therapy. In this study, we engineered a further attenuated pseudorabies virus (PRV) vaccine strain that incorporates a PD-L1 inhibitor and demonstrated its promise as an oncolytic virus in tumor therapy. We first showed that the naturally attenuated PRV vaccine strain Bartha can efficiently infect tumor cells from multiple species, including humans, mice, and dogs in vitro. We then evaluated the safety and anti-tumor efficacy of this vaccine strain and its different single-gene deletion mutants using the B16-F10 melanoma mouse model. The TK deletion strain emerged as the optimal vector, and we inserted a PD-L1 inhibitor (iPD-L1) into it using CRISPR/Cas9 technology. Compared with the control, the recombinant PRV (rPRV-iPD-L1) exhibited more dramatic anti-tumor effects in the B16-F10 melanoma mouse model. Our study suggests that PRV can be developed not only as an oncolytic virus but also a powerful vector for expressing foreign genes to modulate the tumor microenvironment.

The investigation of oncolytic viruses in the field of cancer therapy

Oncolytic viruses (OVs) have emerged as a potential strategy for tumor treatment due to their ability to selectively replicate in tumor cells, induce apoptosis, and stimulate immune responses. However, the therapeutic efficacy of single OVs is limited by the complexity and immunosuppressive nature of the tumor microenvironment (TME). To overcome these challenges, engineering OVs has become an important research direction. This review focuses on engineering methods and multi-modal combination therapies for OVs aimed at addressing delivery barriers, viral phagocytosis, and antiviral immunity in tumor therapy. The engineering approaches discussed include enhancing in vivo immune response, improving replication efficiency within the tumor cells, enhancing safety profiles, and improving targeting capabilities. In addition, this review describes the potential mechanisms of OVs combined with radiotherapy, chemotherapy, cell therapy and immune checkpoint inhibitors (ICIs), and summarizes the data of ongoing clinical trials. By continuously optimizing engineering strategies and combination therapy programs, we can achieve improved treatment outcomes and quality of life for cancer patients.

Glycosylphosphatidylinositol anchor biosynthesis pathway-based biomarker identification with machine learning for prognosis and T cell exhaustion status prediction in breast cancer

As the primary component of anti-tumor immunity, T cells are prone to exhaustion and dysfunction in the tumor microenvironment (TME). A thorough understanding of T cell exhaustion (TEX) in the TME is crucial for effectively addressing TEX in clinical settings and promoting the efficacy of immune checkpoint blockade therapies. In eukaryotes, numerous cell surface proteins are tethered to the plasma membrane via Glycosylphosphatidylinositol (GPI) anchors, which play a crucial role in facilitating the proper translocation of membrane proteins. However, the available evidence is insufficient to support any additional functional involvement of GPI anchors. Here, we investigate the signature of GPI-anchor biosynthesis in the TME of breast cancer (BC)patients, particularly its correlation with TEX. GPI-anchor biosynthesis should be considered as a prognostic risk factor for BC. Patients with high GPI-anchor biosynthesis showed more severe TEX. And the levels of GPI-anchor biosynthesis in exhausted CD8 T cells was higher than normal CD8 T cells, which was not observed between malignant epithelial cells and normal mammary epithelial cells. In addition, we also found that GPI -anchor biosynthesis related genes can be used to diagnose TEX status and predict prognosis in BC patients, both the TEX diagnostic model and the prognostic model showed good AUC values. Finally, we confirmed our findings in cells and clinical samples. Knockdown of PIGU gene expression significantly reduced the proliferation rate of MDA-MB-231 and MCF-7 cell lines. Immunofluorescence results from clinical samples showed reduced aggregation of CD8 T cells in tissues with high expression of GPAA1 and PIGU.

An Update on the Clinical Status, Challenges, and Future Directions of Oncolytic Virotherapy for Malignant Gliomas

OPINION STATEMENT

Malignant gliomas are common central nervous system tumors that pose a significant clinical challenge due to the lack of effective treatments. Glioblastoma (GBM), a grade 4 malignant glioma, is the most prevalent primary malignant brain tumor and is associated with poor prognosis. Current clinical trials are exploring various strategies to combat GBM, with oncolytic viruses (OVs) appearing particularly promising. In addition to ongoing and recently completed clinical trials, one OV (Teserpaturev, Delytact®) received provisional approval for GBM treatment in Japan. OVs are designed to selectively target and eliminate cancer cells while promoting changes in the tumor microenvironment that can trigger and support long-lasting anti-tumor immunity. OVs offer the potential to remodel the tumor microenvironment and reverse systemic immune exhaustion. Additionally, an increasing number of OVs are armed with immunomodulatory payloads or combined with immunotherapy approaches in an effort to promote anti-tumor responses in a tumor-targeted manner. Recently completed oncolytic virotherapy trials can guide the way for future treatment individualization through patient preselection, enhancing the likelihood of achieving the highest possible clinical success. These trials also offer valuable insight into the numerous challenges inherent in malignant glioma treatment, some of which OVs can help overcome.

The Role of Natural Killer Cells in Oncolytic Virotherapy: Friends or Foes?

Oncolytic virotherapy (OVT) has emerged as a promising cancer immunotherapy, and is capable of potentiating other immunotherapies due to its capacity to increase tumor immunogenicity and to boost host antitumor immunity. Natural killer (NK) cells are a critical cellular component for mediating the antitumor response, but hold a mixed reputation for their role in mediating the therapeutic efficacy of OVT. This review will discuss the pros and cons of how NK cells impact OVT, and how to harness this knowledge for the development of effective strategies that could modulate NK cells to improve OVT-based therapeutic outcomes.

Immune landscape and response to oncolytic virus-based immunotherapy

Oncolytic virus (OV)-based immunotherapy has emerged as a promising strategy for cancer treatment, offering a unique potential to selectively target malignant cells while sparing normal tissues. However, the immunosuppressive nature of tumor microenvironment (TME) poses a substantial hurdle to the development of OVs as effective immunotherapeutic agents, as it restricts the activation and recruitment of immune cells. This review elucidates the potential of OV-based immunotherapy in modulating the immune landscape within the TME to overcome immune resistance and enhance antitumor immune responses. We examine the role of OVs in targeting specific immune cell populations, including dendritic cells, T cells, natural killer cells, and macrophages, and their ability to alter the TME by inhibiting angiogenesis and reducing tumor fibrosis. Additionally, we explore strategies to optimize OV-based drug delivery and improve the efficiency of OV-mediated immunotherapy. In conclusion, this review offers a concise and comprehensive synopsis of the current status and future prospects of OV-based immunotherapy, underscoring its remarkable potential as an effective immunotherapeutic agent for cancer treatment.

Expression of B7-H3 and TIM-3 in gastric-type endocervical adenocarcinoma: prevalence, association with PD-L1 expression, and prognostic significance

Gastric-type endocervical adenocarcinoma (GEA) is the second most common subtype of endocervical adenocarcinoma and has a poor prognosis. Anti-programmed death-1 and anti-programmed death-ligand 1 (PD-L1) inhibitors have emerged as a major treatment option for GEA; however, data on the expression of other immune checkpoints in GEA are limited. We analyzed the expression of T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) and B7 homolog 3 protein (B7-H3) in 58 GEA and investigated their prognostic significance as well as association with PD-L1 expression and other known prognostic factors. Applying the tumor proportion score (TPS) with a cutoff of 1%, B7-H3 and TIM-3 were present in 48.3% and 17.2% of cases, respectively. Applying the combined positive score (CPS) with a cutoff of 1, TIM-3 expression was present in 70.7% of cases. Moreover, the expression of three checkpoints (B7-H3, TIM-3, and PD-L1) was incompletely overlapping. Patients with B7-H3 positive tumors (by TPS) or TIM-3 positive tumors (by TPS) had significantly worse recurrence-free survival (RFS) and overall survival (OS) (log-rank). Using CPS, patients with TIM-3 positive tumors showed significantly worse RFS (log-rank). Similarly, B7-H3 positivity (by TPS) and TIM-3 positivity (by TPS) were associated with worse RFS and OS in univariate analysis. TIM-3 positivity (by CPS) was associated with worse RFS in univariate analysis and the final Cox multivariate analysis. In conclusion, our results show that (1) B7-H3 and TIM-3 are frequently expressed in GEA and their expression overlaps incompletely with PD-L1; and (2) both B7-H3 and TIM-3 are independent negative prognostic markers in GEA.

Intratumoral delivery of a Tim-3 antibody-encoding oncolytic adenovirus engages an effective antitumor immune response in liver cancer

BACKGROUND AND PURPOSE

The use of oncolytic viruses as a gene therapy vector is an area of active biomedical research, particularly in the context of cancer treatment. However, the actual therapeutic success of this approach to tumor elimination remains limited. As such, the present study was developed with the goal of simultaneously enhancing the antitumor efficacy of oncolytic viruses and the local immune response by combining the Ad-GD55 oncolytic adenovirus and an antibody specific for the TIM-3 immune checkpoint molecule (α-TIM-3).

APPROACH AND KEY RESULTS

The results of Virus and cell-mediated cytotoxicity assay, qPCR, and Western immunoblotting showed that Ad-GD55-α-Tim-3 oncolytic adenovirus is capable of inducing α-TIM-3 expression within hepatoma cells upon infection, and Ad-GD55-α-TIM-3 exhibited inhibitory efficacy superior to that of Ad-GD55 when used to treat these tumor cells together with the induction of enhanced intracellular immunity. In vivo experiments revealed that Ad-GD55-α-TIM-3 administration was sufficient to inhibit tumor growth and engage in a more robust local immune response within the simulated tumor immune microenvironment.

CONCLUSION AND IMPLICATIONS

These results highlighted the promising therapeutic effects of Ad-GD55-α-TIM-3 oncolytic adenovirus against HCC in vitro and in vivo. As such, this Ad-GD55-α-TIM-3 oncolytic adenovirus may represent a viable approach to the treatment of hepatocellular carcinoma.

Recruiting In Vitro Transcribed mRNA against Cancer Immunotherapy: A Contemporary Appraisal of the Current Landscape

Over 100 innovative in vitro transcribed (IVT)-mRNAs are presently undergoing clinical trials, with a projected substantial impact on the pharmaceutical market in the near future. Τhe idea behind this is that after the successful cellular internalization of IVT-mRNAs, they are subsequently translated into proteins with therapeutic or prophylactic relevance. Simultaneously, cancer immunotherapy employs diverse strategies to mobilize the immune system in the battle against cancer. Therefore, in this review, the fundamental principles of IVT-mRNA to its recruitment in cancer immunotherapy, are discussed and analyzed. More specifically, this review paper focuses on the development of mRNA vaccines, the exploitation of neoantigens, as well as Chimeric Antigen Receptor (CAR) T-Cells, showcasing their clinical applications and the ongoing trials for the development of next-generation immunotherapeutics. Furthermore, this study investigates the synergistic potential of combining the CAR immunotherapy and the IVT-mRNAs by introducing our research group novel, patented delivery method that utilizes the Protein Transduction Domain (PTD) technology to transduce the IVT-mRNAs encoding the CAR of interest into the Natural Killer (NK)-92 cells, highlighting the potential for enhancing the CAR NK cell potency, efficiency, and bioenergetics. While IVT-mRNA technology brings exciting progress to cancer immunotherapy, several challenges and limitations must be acknowledged, such as safety, toxicity, and delivery issues. This comprehensive exploration of IVT-mRNA technology, in line with its applications in cancer therapeutics, offers valuable insights into the opportunities and challenges in the evolving landscape of cancer immunotherapy, setting the stage for future advancements in the field.

Hypoxia effects on oncolytic virotherapy in Cancer: Friend or Foe?

Researchers have tried to find novel strategies for cancer treatment in the past decades. Among the utilized methods, administering oncolytic viruses (OVs) alone or combined with other anticancer therapeutic approaches has had promising outcomes, especially in solid tumors. Infecting the tumor cells by these viruses can lead to direct lysis or induction of immune responses. However, the immunosuppressive tumor microenvironment (TME) is considered a significant challenge for oncolytic virotherapy in treating cancer. Based on OV type, hypoxic conditions in the TME can accelerate or repress virus replication. Therefore, genetic manipulation of OVs or other molecular modifications to reduce hypoxia can induce antitumor responses. Moreover, using OVs with tumor lysis capability in the hypoxic TME may be an attractive strategy to overcome the limitations of the therapy. This review summarizes the latest information available in the field of cancer virotherapy and discusses the dual effect of hypoxia on different types of OVs to optimize available related therapeutic methods.

Oncolytic Viruses and Immune Checkpoint Inhibitors: The "Hot" New Power Couple

Immune checkpoint inhibitors (ICIs) have revolutionized cancer care and shown remarkable efficacy clinically. This efficacy is, however, limited to subsets of patients with significant infiltration of lymphocytes into the tumour microenvironment. To extend their efficacy to patients who fail to respond or achieve durable responses, it is now becoming evident that complex combinations of immunomodulatory agents may be required to extend efficacy to patients with immunologically "cold" tumours. Oncolytic viruses (OVs) have the capacity to selectively replicate within and kill tumour cells, resulting in the induction of immunogenic cell death and the augmentation of anti-tumour immunity, and have emerged as a promising modality for combination therapy to overcome the limitations seen with ICIs. Pre-clinical and clinical data have demonstrated that OVs can increase immune cell infiltration into the tumour and induce anti-tumour immunity, thus changing a "cold" tumour microenvironment that is commonly associated with poor response to ICIs, to a "hot" microenvironment which can render patients more susceptible to ICIs. Here, we review the major viral vector platforms used in OV clinical trials, their success when used as a monotherapy and when combined with adjuvant ICIs, as well as pre-clinical studies looking at the effectiveness of encoding OVs to deliver ICIs locally to the tumour microenvironment through transgene expression.

Lighting Up the Fire in the Microenvironment of Cold Tumors: A Major Challenge to Improve Cancer Immunotherapy

Immunotherapy includes immune checkpoint inhibitors (ICI) such as antibodies targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) or the programmed cell death protein/programmed death ligand 1 (PD-1/PD-L1) axis. Experimental and clinical evidence show that immunotherapy based on immune checkpoint inhibitors (ICI) provides long-term survival benefits to cancer patients in whom other conventional therapies have failed. However, only a minority of patients show high clinical benefits via the use of ICI alone. One of the major factors limiting the clinical benefits to ICI can be attributed to the lack of immune cell infiltration within the tumor microenvironment. Such tumors are classified as "cold/warm" or an immune "desert"; those displaying significant infiltration are considered "hot" or inflamed. This review will provide a brief summary of different tumor properties contributing to the establishment of cold tumors and describe major strategies that could reprogram non-inflamed cold tumors into inflamed hot tumors. More particularly, we will describe how targeting hypoxia can induce metabolic reprogramming that results in improving and extending the benefit of ICI.

Overcoming acquired resistance to cancer immune checkpoint therapy: potential strategies based on molecular mechanisms

Immune checkpoint inhibitors (ICIs) targeting CTLA-4 and PD-1/PD-L1 to boost tumor-specific T lymphocyte immunity have opened up new avenues for the treatment of various histological types of malignancies, with the possibility of durable responses and improved survival. However, the development of acquired resistance to ICI therapy over time after an initial response remains a major obstacle in cancer therapeutics. The potential mechanisms of acquired resistance to ICI therapy are still ambiguous. In this review, we focused on the current understanding of the mechanisms of acquired resistance to ICIs, including the lack of neoantigens and effective antigen presentation, mutations of IFN-γ/JAK signaling, and activation of alternate inhibitory immune checkpoints, immunosuppressive tumor microenvironment, epigenetic modification, and dysbiosis of the gut microbiome. Further, based on these mechanisms, potential therapeutic strategies to reverse the resistance to ICIs, which could provide clinical benefits to cancer patients, are also briefly discussed.

Checkpoint blockade meets gene therapy: Opportunities to improve response and reduce toxicity

Immune checkpoint inhibitors (ICIs) based on monoclonal antibodies represent a breakthrough for the treatment of cancer. However, their efficacy varies among tumor types and patients, and they can lead to adverse effects due to on-target/off-tumor activity, since they are administered systemically at high doses. An alternative and attractive approach for the delivery of ICIs is the use of gene therapy vectors able to express them in vivo. This review focuses on the most recent studies using viral vectors able to express ICIs locally or systemically in preclinical models of cancer. These vectors include non-replicating viruses, oncolytic viruses able to propagate specifically in tumor cells and destroy them, and self-amplifying RNA vectors, armed with different formats of antibodies against immune checkpoints. Non-replicating vectors usually lead to long-term ICI expression, potentially eliminating the need for repeated administration. Vectors with replication capacity, although they have a shorter window of expression, can induce inflammation which enhances the antitumor effect. Finally, these engineered vectors can be used in combination with other immunostimulatory molecules or with CAR-T cells, further boosting the antitumor immune responses.

Establishment of humanized mice and its application progress in cancer immunotherapy

The current high prevalence of malignant tumors has attracted considerable attention, and treating advanced malignancies is becoming increasingly difficult. Although immunotherapy is a hopeful alternative, it is effective in only a few people. Thus, development of preclinical animal models is needed. Humanized xenotransplantation mouse models can help with selecting treatment protocols, evaluating curative effects and assessing prognosis. This review discusses the establishment of humanized mouse models and their application prospects in cancer immunotherapy to identify tailored therapies for individual patients.

Local Delivery of Immunomodulatory Antibodies for Gastrointestinal Tumors

Cancer therapy has experienced a breakthrough with the use of immune checkpoint inhibitors (ICIs) based on monoclonal antibodies (mAbs), which are able to unleash immune responses against tumors refractory to other therapies. Despite the great advancement that ICIs represent, most patients with gastrointestinal tumors have not benefited from this therapy. In addition, ICIs often induce adverse effects that are related to their systemic use. Local administration of ICIs in tumors could concentrate their effect in the malignant tissue and provide a higher safety profile. A new and attractive approach for local delivery of ICIs is the use of gene therapy vectors to express these blocking antibodies in tumor cells. Several vectors have been evaluated in preclinical models of gastrointestinal tumors to express ICIs against PD-1, PD-L1, and CTLA-4, among other immune checkpoints, with promising results. Vectors used in these settings include oncolytic viruses, self-replicating RNA vectors, and non-replicative viral and non-viral vectors. The use of viral vectors, especially when they have replication capacity, provides an additional adjuvant effect that has been shown to enhance antitumor responses. This review covers the most recent studies involving the use of gene therapy vectors to deliver ICIs to gastrointestinal tumors.

A multidimensional pan-cancer analysis of DCAF13 and its protumorigenic effect in lung adenocarcinoma

DCAF13 is a substrate recognition protein in the ubiquitin-proteasome system with oncogenic effects in several malignant tumors. However, it is unclear that the relationship between DCAF13 expression pattern and prognosis across different cancer types. Also unknown is the biological function or effects on the immune microenvironment of DCAF13. In this study, we parsed multiple public databases to explore the potential tumorigenic actions of DCAF13, including correlations with prognosis, microsatellite instability (MSI), tumor mutational burden (TMB), immune checkpoint genes, immune cell infiltration, and immunotherapy response in pan-cancer. Moreover, we validated DCAF13 expression in a tissue microarray by immunohistochemistry and investigate its effects in vitro and in vivo. The results showed that DCAF13 was upregulated in 17 cancer types and correlated with poor prognosis in many cancers. Also, the correlation between DCAF13 and TMB was found in 14 cancers as well as MSI in nine. The expression level of DCAF13 was found to be notably correlated with immune cell infiltration, showing a negative correlation with CD4 T cell infiltration and a positive correlation with neutrophil infiltration. The oncogene DCAF13 expression was shown to have a positive correlation with CD274 or ADORA2A and negative correlation with VSIR, TNFRSF4, or TNFRSF14 across large subsets of human cancers. Finally, we observed that DCAF13 was highly expressed in a tissue microarray of lung cancer. In immunocompromised mouse models, xenograft growth of human lung cancer cells was significantly inhibited by DCAF13 knockdown. Our results highlighted the value of DCAF13 as a promising independent predictor of poor prognosis through numerous biological processes. High DCAF13 expression often predicts suppressive immune microenvironment and immunotherapy resistance in a pan-cancer context.

Novel technologies for applying immune checkpoint blockers

Cancer cells develop several ways to subdue the immune system among others via upregulation of inhibitory immune checkpoint (ICP) proteins. These ICPs paralyze immune effector cells and thereby enable unfettered tumor growth. Monoclonal antibodies (mAbs) that block ICPs can prevent immune exhaustion. Due to their outstanding effects, mAbs revolutionized the field of cancer immunotherapy. However, current ICP therapy regimens suffer from issues related to systemic administration of mAbs, including the onset of immune related adverse events, poor pharmacokinetics, limited tumor accessibility and immunogenicity. These drawbacks and new insights on spatiality prompted the exploration of novel administration routes for mAbs for instance peritumoral delivery. Moreover, novel ICP drug classes that are adept to novel delivery technologies were developed to circumvent the drawbacks of mAbs. We therefore review the state-of-the-art and novel delivery strategies of ICP drugs.

Managing the immune microenvironment of osteosarcoma: the outlook for osteosarcoma treatment

Osteosarcoma, with poor survival after metastasis, is considered the most common primary bone cancer in adolescents. Notwithstanding the efforts of researchers, its five-year survival rate has only shown limited improvement, suggesting that existing therapeutic strategies are insufficient to meet clinical needs. Notably, immunotherapy has shown certain advantages over traditional tumor treatments in inhibiting metastasis. Therefore, managing the immune microenvironment in osteosarcoma can provide novel and valuable insight into the multifaceted mechanisms underlying the heterogeneity and progression of the disease. Additionally, given the advances in nanomedicine, there exist many advanced nanoplatforms for enhanced osteosarcoma immunotherapy with satisfactory physiochemical characteristics. Here, we review the classification, characteristics, and functions of the key components of the immune microenvironment in osteosarcoma. This review also emphasizes the application, progress, and prospects of osteosarcoma immunotherapy and discusses several nanomedicine-based options to enhance the efficiency of osteosarcoma treatment. Furthermore, we examine the disadvantages of standard treatments and present future perspectives for osteosarcoma immunotherapy.

Overcoming Suppressive Tumor Microenvironment by Vaccines in Solid Tumor

Conventional vaccines are widely used to boost human natural ability to defend against foreign invaders, such as bacteria and viruses. Recently, therapeutic cancer vaccines attracted the most attention for anti-cancer therapy. According to the main components, it can be divided into five types: cell, DNA, RNA, peptide, and virus-based vaccines. They mainly perform through two rationales: (1) it trains the host immune system to protect itself and effectively eradicate cancer cells; (2) these vaccines expose the immune system to molecules associated with cancer that enable the immune system to recognize and destroy cancer cells. In this review, we thoroughly summarized the potential strategies and technologies for developing cancer vaccines, which may provide critical achievements for overcoming the suppressive tumor microenvironment through vaccines in solid tumors.

Counteracting Immunosuppression in the Tumor Microenvironment by Oncolytic Newcastle Disease Virus and Cellular Immunotherapy

An apparent paradox exists between the evidence for spontaneous systemic T cell- mediated anti-tumor immune responses in cancer patients, observed particularly in their bone marrow, and local tumor growth in the periphery. This phenomenon, known as "concomitant immunity" suggests that the local tumor and its tumor microenvironment (TME) prevent systemic antitumor immunity to become effective. Oncolytic Newcastle disease virus (NDV), an agent with inherent anti-neoplastic and immune stimulatory properties, is capable of breaking therapy resistance and immunosuppression. This review updates latest information about immunosuppression by the TME and discusses mechanisms of how oncolytic viruses, in particular NDV, and cellular immunotherapy can counteract the immunosuppressive effect of the TME. With regard to cellular immunotherapy, the review presents pre-clinical studies of post-operative active-specific immunotherapy and of adoptive T cell-mediated therapy in immunocompetent mice. Memory T cell (MTC) transfer in tumor challenged T cell-deficient nu/nu mice demonstrates longevity and functionality of these cells. Graft-versus-leukemia (GvL) studies in mice demonstrate complete remission of late-stage disease including metastases and cachexia. T cell based immunotherapy studies with human cells in human tumor xenotransplanted NOD/SCID mice demonstrate superiority of bone marrow-derived as compared to blood-derived MTCs. Results from clinical studies presented include vaccination studies using two different types of NDV-modified cancer vaccine and a pilot adoptive T-cell mediated therapy study using re-activated bone marrow-derived cancer-reactive MTCs. As an example for what can be expected from clinical immunotherapy against tumors with an immunosuppressive TME, results from vaccination studies are presented from the aggressive brain tumor glioblastoma multiforme. The last decades of basic research in virology, oncology and immunology can be considered as a success story. Based on discoveries of these research areas, translational research and clinical studies have changed the way of treatment of cancer by introducing and including immunotherapy.