Cancer immunotherapy with recombinant poliovirus induces IFN-dominant activation of dendritic cells and tumor antigen-specific CTLs

Glioblastoma Vaccines as Promising Immune-Therapeutics: Challenges and Current Status

Glioblastoma (GBM) is the most common and aggressive malignant brain tumor. Standard treatments including surgical resection, radiotherapy, and chemotherapy, have failed to significantly improve the prognosis of glioblastoma patients. Currently, immunotherapeutic approaches based on vaccines, chimeric antigen-receptor T-cells, checkpoint inhibitors, and oncolytic virotherapy are showing promising results in clinical trials. The combination of different immunotherapeutic approaches is proving satisfactory and promising. In view of the challenges of immunotherapy and the resistance of glioblastomas, the treatment of these tumors requires further efforts. In this review, we explore the obstacles that potentially influence the efficacy of the response to immunotherapy and that should be taken into account in clinical trials. This article provides a comprehensive review of vaccine therapy for glioblastoma. In addition, we identify the main biomarkers, including isocitrate dehydrogenase, epidermal growth factor receptor, and telomerase reverse transcriptase, known as potential immunotherapeutic targets in glioblastoma, as well as the current status of clinical trials. This paper also lists proposed solutions to overcome the obstacles facing immunotherapy in glioblastomas.

Novel Clinical Trials and Approaches in the Management of Glioblastoma

PURPOSE OF REVIEW

The purpose of this review is to discuss a wide variety of novel therapies recently studied or actively undergoing study in patients with glioblastoma. This review also discusses current and future strategies for improving clinical trial design in patients with glioblastoma to maximize efficacy in discovering effective treatments.

RECENT FINDINGS

Over the years, there has been significant expansion in therapy modalities studied in patients with glioblastoma. These therapies include, but are not limited to, targeted molecular therapies, DNA repair pathway targeted therapies, immunotherapies, vaccine therapies, and surgically targeted radiotherapies. Glioblastoma is the most common malignant primary brain tumor in adults and unfortunately remains with poor overall survival following the current standard of care. Given the dismal prognosis, significant clinical and research efforts are ongoing with the goal of improving patient outcomes and enhancing quality and quantity of life utilizing a wide variety of novel therapies.

The golden key to open mystery boxes of SMARCA4-deficient undifferentiated thoracic tumor: focusing immunotherapy, tumor microenvironment and epigenetic regulation

SMARCA4-deficient undifferentiated thoracic tumor is extremely invasive. This tumor with poor prognosis is easily confused with SMARCA4-deficent non-small cell lung cancer or sarcoma. Standard and efficient treatment has not been established. In this review, we summarized the etiology, pathogenesis and diagnosis, reviewed current and proposed innovative strategies for treatment and improving prognosis. Immunotherapy, targeting tumor microenvironment and epigenetic regulator have improved the prognosis of cancer patients. We summarized clinicopathological features and immunotherapy strategies and analyzed the progression-free survival (PFS) and overall survival (OS) of patients with SMARCA4-UT who received immune checkpoint inhibitors (ICIs). In addition, we proposed the feasibility of epigenetic regulation in the treatment of SMARCA4-UT. To our knowledge, this is the first review that aims to explore innovative strategies for targeting tumor microenvironment and epigenetic regulation and identify potential benefit population for immunotherapy to improve the prognosis.

Focus on current and emerging treatment options for glioma: A comprehensive review

This comprehensive review delves into the current updates and challenges associated with the management of low-grade gliomas (LGG), the predominant primary tumors in the central nervous system. With a general incidence rate of 5.81 per 100000, gliomas pose a significant global concern, necessitating advancements in treatment techniques to reduce mortality and morbidity. This review places a particular focus on immunotherapies, discussing promising agents such as Zotiraciclib and Lerapolturev. Zotiraciclib, a CDK9 inhibitor, has demonstrated efficacy in glioblastoma treatment in preclinical and clinical studies, showing its potential as a therapeutic breakthrough. Lerapolturev, a viral immunotherapy, induces inflammation in glioblastoma and displays positive outcomes in both adult and pediatric patients. Exploration of immunotherapy extends to Pembrolizumab, Nivolumab, and Entrectinib, revealing the challenges and variabilities in patient responses. Despite promising preclinical data, the monoclonal antibody Depatuxizumab has proven ineffective in glioblastoma treatment, emphasizing the critical need to understand resistance mechanisms. The review also covers the success of radiation therapy in pediatric LGG, with evolving techniques, such as proton therapy, showing potential improvements in patient quality of life. Surgical treatment is discussed in the context of achieving a balance between preserving the patient's quality of life and attaining gross total resection, with the extent of surgical resection significantly influencing the survival outcomes. In addition to advancements in cancer vaccine development, this review highlights the evolving landscape of LGG treatment, emphasizing a shift toward personalized and targeted therapies. Ongoing research is essential for refining strategies and enhancing outcomes in the management of LGG.

CD155 as an emerging target in tumor immunotherapy

CD155 is an immunoglobulin-like protein overexpressed in almost all the tumor cells, which not only promotes proliferation, adhesion, invasion, and migration of tumor cells, but also regulates immune responses by interacting with TIGIT, CD226 or CD96 receptors expressed on several immune cells, thereby modulating the functionality of these cellular subsets. As a novel immune checkpoint, the inhibition of CD155/TIGIT, either as a standalone treatment or in conjunction with other immune checkpoint inhibitors, has demonstrated efficacy in managing advanced solid malignancies. In this review, we summarize the intricate relationship between on tumor surface CD155 and its receptors, with further discussion on how they regulate the occurrence of tumor immune escape. In addition, novel therapeutic strategies and clinical trials targeting CD155 and its receptors are summarized, providing a strong rationale and way forward for the development of next-generation immunotherapies.

Molecular insights and promise of oncolytic virus based immunotherapy

Discovering a therapeutic that can counteract the aggressiveness of this disease's mechanism is crucial for improving survival rates for cancer patients and for better understanding the most different types of cancer. In recent years, using these viruses as an anticancer therapy has been thought to be successful. They mostly work by directly destroying cancer cells, activating the immune system to fight cancer, and expressing exogenous effector genes. For the treatment of tumors, oncolytic viruses (OVs), which can be modified to reproduce only in tumor tissues and lyse them while preserving the healthy non-neoplastic host cells and reinstating antitumor immunity which present a novel immunotherapeutic strategy. OVs can exist naturally or be created in a lab by altering existing viruses. These changes heralded the beginning of a new era of less harmful virus-based cancer therapy. We discuss three different types of oncolytic viruses that have already received regulatory approval to treat cancer as well as clinical research using oncolytic adenoviruses. The primary therapeutic applications, mechanism of action of oncolytic virus updates, future views of this therapy will be covered in this chapter.

Discovery of Novel Isoquinoline Analogues as Dual Tubulin Polymerization/V-ATPase Inhibitors with Immunogenic Cell Death Induction

Cancer immunotherapy has revolutionized clinical advances in a variety of cancers. Due to the low immunogenicity of the tumor, only a few patients can benefit from it. Specific microtubule inhibitors can effectively induce immunogenic cell death and improve immunogenicity of the tumor. A series of isoquinoline derivatives based on the natural products podophyllotoxin and diphyllin were designed and synthesized. Among them, F10 showed robust antiproliferation activity against four human cancer cell lines, and it was verified that F10 exerted antiproliferative activity by inhibiting tubulin and V-ATPase. Further studies indicated that F10 is able to induce immunogenic cell death in addition to apoptosis. Meanwhile, F10 inhibited tumor growth in an RM-1 homograft model with enhanced T lymphocyte infiltration. These results suggest that F10 may be a promising lead compound for the development of a new generation of microtubule drugs.

The Development and Characterization of a Next-Generation Oncolytic Virus Armed with an Anti-PD-1 sdAb for Osteosarcoma Treatment In Vitro

Osteosarcoma (OS) is a primary bone malignancy characterized by an aggressive nature, limited treatment options, low survival rate, and poor patient prognosis. Conditionally replicative adenoviruses (CRAds) armed with immune checkpoint inhibitors hold great potential for enhanced therapeutic efficacy. The present study aims to investigate the anti-tumor efficacy of CAV2-AU-M2, a CAV2-based CRAd armed with an anti-PD-1 single-domain antibody (sdAb), against OS cell lines in vitro. The infection, conditional replication, cytopathic effects, and cytotoxicity of CAV2-AU-M2 were tested in four different OS cell lines in two-dimensional (2D) and three-dimensional (3D) cell cultures. CAV2-AU-M2 showed selective replication in the OS cells and induced efficient tumor cell lysis and death. Moreover, CAV2-AU-M2 produced an anti-PD-1 sdAb that demonstrated effective binding to the PD-1 receptors. This study demonstrated the first CRAd armed with an anti-PD-1 sdAb. This combined approach of two distinct immunotherapies is intended to enhance the anti-tumor immune response in the tumor microenvironment.

Delivery of Interferon β-Encoding Plasmid via Lipid Nanoparticle Restores Interferon β Expression to Enhance Antitumor Immunity in Colon Cancer

Type I interferon (IFN-I) plays a critical role in host cancer immunosurveillance, but its expression is often impaired in the tumor microenvironment. We aimed at testing the hypothesis that cationic lipid nanoparticle delivery of interferon β (IFNβ)-encoding plasmid to tumors is effective in restoring IFNβ expression to suppress tumor immune evasion. We determined that IFN-I function in tumor suppression depends on the host immune cells. IFN-I activates the expression of Cxcl9 and Cxcl10 to enhance T cell tumor infiltration. RNA-Seq detected a low level of IFNα13 and IFNβ in colon tumor tissue. scRNA-Seq revealed that IFNβ is expressed in immune cell subsets in non-neoplastic human tissues and to a lesser degree in human colon tumor tissues. Forced expression of IFNα13 and IFNβ in colon tumor cells up-regulates major histocompatibility complex I (MHC I) expression and suppresses colon tumor growth in vivo. In human cancer patients, IFNβ expression is positively correlated with human leukocyte antigen (HLA) expression, and IFN-I signaling activation correlates with the patient response to PD-1 blockade immunotherapy. To translate this finding to colon cancer immunotherapy, we formulated a 1,2-dioleoyl-3-trimethylammonium propane (DOTAP)-cholesterol-encapsulated IFNβ-encoding plasmid (IFNBCOL01). IFNBCOL01 transfects colon tumor cells to express IFNβ to increase the level of MHC I expression. IFNBCOL01 therapy transfects tumor cells and tumor-infiltrating immune cells to produce IFNβ to activate MHC I and granzyme B expression and inhibits colon tumor growth in mice. Our data determine that lipid nanoparticle delivery of IFNβ-encoding plasmid DNA enhances tumor immunogenicity and T cell effector function to suppress colon tumor growth in vivo.

Elucidating cellular response to treatment with viral immunotherapies in pediatric high-grade glioma and medulloblastoma

HSV G207, a double-stranded, DNA virus, and the polio:rhinovirus chimera, PVSRIPO, a single positive-strand RNA virus, are viral immunotherapies being used to treat pediatric malignant brain tumors in clinical trials. The purpose of this work is to elucidate general response patterns and putative biomarkers of response. Multiple pediatric high-grade glioma and medulloblastoma cell lines were treated with various multiplicities of infection of G207 or PVSRIPO. There was a significant inverse correlation between expression of one HSV cellular receptor, CD111, and the lethal dose of 50% of cells (LD50) of cells treated with G207 (r = -0.985, P<0.001) but no correlation between PVSRIPO cellular receptor expression (CD155) and LD50. RNA sequencing of control cells and cells treated for 8 and 24 h revealed that there were few shared differentially expressed (DE) genes between cells treated with PVSRIPO and G207: GCLM, LANCL2, and RBM3 were enriched whilst ADAMTS1 and VEGFA were depleted. Likewise, there were few shared DE genes enriched between medulloblastoma and high-grade glioma cell lines treated with G207: GPSM2, CHECK2, SEPTIN2, EIF4G2, GCLM, GDAP1, LANCL2, and PWP1.  Treatment with G207 and PVSRIPO appear to cause disparate gene enrichment and depletion suggesting disparate molecular mechanisms in malignant pediatric brain tumors.

An in vitro-transcribed circular RNA targets the mitochondrial inner membrane cardiolipin to ablate EIF4G2+/PTBP1+ pan-adenocarcinoma

In vitro-transcribed (IVT) mRNA has arisen as a rapid method for the production of nucleic acid drugs. Here, we have constructed an oncolytic IVT mRNA that utilizes human rhinovirus type 2 (HRV2) internal ribosomal entry sites (IRESs) to selectively trigger translation in cancer cells with high expression of EIF4G2 and PTBP1. The oncolytic effect was provided by a long hGSDMDc .825 T>A/c.884 A>G-F1LCT mutant mRNA sequence with mitochondrial inner membrane cardiolipin targeting toxicity that triggers mitophagy. Utilizing the permuted intron-exon (PIE) splicing circularization strategy and lipid nanoparticle (LNP) encapsulation reduced immunogenicity of the mRNA and enabled delivery to eukaryotic cells in vivo. Engineered HRV2 IRESs-GSDMDp.D275E/E295G-F1LCT circRNA-LNPs (GSDMDENG circRNA) successfully inhibited EIF4G2+/PTBP1+ pan-adenocarcinoma xenografts growth. Importantly, in a spontaneous tumor model with abnormal EIF4G2 and PTBP1 caused by KRAS G12D mutation, GSDMDENG circRNA significantly prevented the occurrence of pancreatic, lung and colon adenocarcinoma, improved the survival rate and induced persistent KRAS G12D tumor antigen-specific cytotoxic T lymphocyte responses.

New Insights into the Link between SARS-CoV-2 Infection and Renal Cancer

Cancer has been described as a risk factor for greater susceptibility to SARS-CoV-2 infection and severe COVID-19, mainly for patients with metastatic disease. Conversely, to that reported for most solid and hematological malignancies, the few available clinical studies reported that the infection did not increase the risk of death in renal cancer patients. The expression on proximal tubular renal cells of the key players in cellular viral uptake, ACE2, TMPRSS2, and NRP1, seems to be the mechanism for the direct kidney injury seen in patients with COVID-19. Interestingly, data from The Cancer Genome Atlas and experimental analyses on various renal cancer cell lines demonstrated that the above-reported receptors/cofactors are maintained by renal cancer cells. However, whether SARS-CoV-2 infection directly kills renal cancer cells or generates enhanced immunogenicity is a question worth investigating. In addition, some researchers have further addressed the topic by studying the expression and prognostic significance of gene signatures related to SARS-CoV-2 infection in renal cancer patients. The emerging data highlights the importance of better understanding the existence of a link between renal cancer and COVID-19 since it could lead to the identification of new prognostic factors and the development of new therapeutic targets in the management of renal cancer patients.

Targeting anticancer immunity in oral cancer: Drugs, products, and nanoparticles

Oral cavity carcinomas are the most frequent malignancies among head and neck malignancies. Oral tumors include not only oral cancer cells with different potency and stemness but also consist of diverse cells, containing anticancer immune cells, stromal and also immunosuppressive cells that influence the immune system reactions. The infiltrated T and natural killer (NK) cells are the substantial tumor-suppressive immune compartments in the tumor. The infiltration of these cells has substantial impacts on the response of tumors to immunotherapy, chemotherapy, and radiotherapy. Nevertheless, cancer cells, stromal cells, and some other compartments like regulatory T cells (Tregs), macrophages, and myeloid-derived suppressor cells (MDSCs) can repress the immune responses against malignant cells. Boosting anticancer immunity by inducing the immune system or repressing the tumor-promoting cells is one of the intriguing approaches for the eradication of malignant cells such as oral cancers. This review aims to concentrate on the secretions and interactions in the oral tumor immune microenvironment. We review targeting tumor stroma, immune system and immunosuppressive interactions in oral tumors. This review will also focus on therapeutic targets and therapeutic agents such as nanoparticles and products with anti-tumor potency that can boost anticancer immunity in oral tumors. We also explain possible future perspectives including delivery of various cells, natural products and drugs by nanoparticles for boosting anticancer immunity in oral tumors.

Reshaping Intratumoral Mononuclear Phagocytes with Antibody-Opsonized Immunometabolic Nanoparticles

Mononuclear phagocytes (MPs) are vital components of host immune defenses against cancer. However, tumor-infiltrating MPs often present tolerogenic and pro-tumorigenic phenotypes via metabolic switching triggered by excessive lipid accumulation in solid tumors. Inspired by viral infection-mediated MP modulation, here enveloped immunometabolic nanoparticles (immeNPs) are designed to co-deliver a viral RNA analog and a fatty acid oxidation regulator for synergistic reshaping of intratumoral MPs. These immeNPs are camouflaged with cancer cell membranes for tumor homing and opsonized with anti-CD163 antibodies for specific MP recognition and uptake. It is found that internalized immeNPs coordinate lipid metabolic reprogramming with innate immune stimulation, inducing M2-to-M1 macrophage repolarization and tolerogenic-to-immunogenic dendritic cell differentiation for cytotoxic T cell infiltration. The authors further demonstrate that the use of immeNPs confers susceptibility to anti-PD-1 therapy in immune checkpoint blockade-resistant breast and ovarian tumors, and thereby provide a promising strategy to expand the potential of conventional immunotherapy.

Early enterovirus translation deficits extend viral RNA replication and elicit sustained MDA5-directed innate signaling

IMPORTANCE

Multiple pattern recognition receptors sense vRNAs and initiate downstream innate signaling: endosomal Toll-like receptors (TLRs) 3, 7, and 8 and cytoplasmic RIG-I-like receptors (RLRs) RIG-I, and MDA5. They engage distinct signaling scaffolds: mitochondrial antiviral signaling protein (RLR), MyD88, and TLR-adaptor interacting with SLC15A4 on the lysosome (TLR7 and TLR8) and toll/IL-1R domain-containing adaptor inducing IFN (TLR3). By virtue of their unusual vRNA structure and direct host cell entry path, the innate response to EVs uniquely is orchestrated by MDA5. We reported that PVSRIPO's profound attenuation and loss of cytopathogenicity triggers MDA5-directed polar TBK1-IRF3 signaling that generates priming of polyfunctional antitumor CD8+ T-cell responses and durable antitumor surveillance in vivo. Here we unraveled EV-host relations that control suppression of host type-I IFN responses and show that PVSRIPO's deficient immediate host eIF4G cleavage generates unopposed MDA5-directed downstream signaling cascades resulting in sustained type-I IFN release.

Methods behind oncolytic virus-based DC vaccines in cancer: Toward a multiphase combined treatment strategy for Glioblastoma (GBM) patients

Glioblastoma (GBM) remains an orphan cancer disease with poor outcome. Novel treatment strategies are needed. Immunotherapy has several modes of action. The addition of active specific immunotherapy with dendritic cell vaccines resulted in improved overall survival of patients. Integration of DC vaccination within the first-line combined treatment became a challenge, and immunogenic cell death immunotherapy during chemotherapy was introduced. We used a retrospective analysis using real world data to evaluate the complex combined treatment, which included individualized multimodal immunotherapy during and after standard of care, and which required adaptations during treatment, and found a further improvement of overall survival. We also discuss the use of real world data as evidence. Novel strategies to move the field of individualized multimodal immunotherapy forward for GBM patients are reviewed.

Oncolytic virus M1 functions as a bifunctional checkpoint inhibitor to enhance the antitumor activity of DC vaccine

Although promising, dendritic cell (DC) vaccines still provide limited clinical benefits, mainly due to the immunosuppressive tumor microenvironment (TME) and the lack of tumor-associated antigens (TAAs). Oncolytic virus therapy is an ideal strategy to overcome immunosuppression and expose TAAs; therefore, they may work synergistically with DC vaccines. In this study, we demonstrate that oncolytic virus M1 (OVM) can enhance the antitumor effects of DC vaccines across diverse syngeneic mouse tumor models by increasing the infiltration of CD8+ effector T cells in the TME. Mechanically, we show that tumor cells counteract DC vaccines through the SIRPα-CD47 immune checkpoint, while OVM can downregulate SIRPα in DCs and CD47 in tumor cells. Since OVM upregulates PD-L1 in DCs, combining PD-L1 blockade with DC vaccines and OVM further enhances antitumor activity. Overall, OVM strengthens the antitumor efficacy of DC vaccines by targeting the SIRPα-CD47 axis, which exerts dominant immunosuppressive effects on DC vaccines.

Modeling of oncolytic viruses in a heterogeneous cell population to predict spread into non-cancerous cells

New cancer treatment modalities that limit patient discomfort need to be developed. One possible new therapy is the use of oncolytic (cancer-killing) viruses. It is only recently that our ability to manipulate viral genomes has allowed us to consider deliberately infecting cancer patients with viruses. One key consideration is to ensure that the virus exclusively targets cancer cells and does not harm nearby non-cancerous cells. Here, we use a mathematical model of viral infection to determine the characteristics a virus would need to have in order to eradicate a tumor, but leave non-cancerous cells untouched. We conclude that the virus must differ in its ability to infect the two different cell types, with the infection rate of non-cancerous cells needing to be less than one hundredth of the infection rate of cancer cells. Differences in viral production rate or infectious cell death rate alone are not sufficient to protect non-cancerous cells.

SARS-CoV-2 infection as a potential risk factor for the development of cancer

The COVID-19 pandemic has a significant impact on public health and the estimated number of excess deaths may be more than three times higher than documented in official statistics. Numerous studies have shown an increased risk of severe COVID-19 and death in patients with cancer. In addition, the role of SARS-CoV-2 as a potential risk factor for the development of cancer has been considered. Therefore, in this review, we summarise the available data on the potential effects of SARS-CoV-2 infection on oncogenesis, including but not limited to effects on host signal transduction pathways, immune surveillance, chronic inflammation, oxidative stress, cell cycle dysregulation, potential viral genome integration, epigenetic alterations and genetic mutations, oncolytic effects and reactivation of dormant cancer cells. We also investigated the potential long-term effects and impact of the antiviral therapy used in COVID-19 on cancer development and its progression.

Polio virotherapy targets the malignant glioma myeloid infiltrate with diffuse microglia activation engulfing the CNS

BACKGROUND

Malignant gliomas commandeer dense inflammatory infiltrates with glioma-associated macrophages and microglia (GAMM) promoting immune suppression, evasion, and tumor progression. Like all cells in the mononuclear phagocytic system, GAMM constitutively express the poliovirus receptor, CD155. Besides myeloid cells, CD155 is widely upregulated in the neoplastic compartment of malignant gliomas. Intratumor treatment with the highly attenuated rhino:poliovirus chimera, PVSRIPO, yielded long-term survival with durable radiographic responses in patients with recurrent glioblastoma (Desjardins et al. New England Journal of Medicine, 2018). This scenario raises questions about the contributions of myeloid versus neoplastic cells to polio virotherapy of malignant gliomas.

METHODS

We investigated PVSRIPO immunotherapy in immunocompetent mouse brain tumor models with blinded, board-certified neuropathologist review, a range of neuropathological, immunohistochemical, and immunofluorescence analyses, and RNAseq of the tumor region.

RESULTS

PVSRIPO treatment caused intense engagement of the GAMM infiltrate associated with substantial, but transient tumor regression. This was accompanied by marked microglia activation and proliferation in normal brain surrounding the tumor, in the ipsilateral hemisphere and extending into the contralateral hemisphere. There was no evidence for lytic infection of malignant cells. PVSRIPO-instigated microglia activation occurred against a backdrop of sustained innate antiviral inflammation, associated with induction of the Programmed Cell Death Ligand 1 (PD-L1) immune checkpoint on GAMM. Combining PVSRIPO with PD1/PD-L1 blockade led to durable remissions.

CONCLUSIONS

Our work implicates GAMM as active drivers of PVSRIPO-induced antitumor inflammation and reveals profound and widespread neuroinflammatory activation of the brain-resident myeloid compartment by PVSRIPO.

CD155 and Its Receptors as Targets for Cancer Therapy

CD155, also known as the poliovirus receptor, is an adhesion molecule often overexpressed in tumors of different origins where it promotes cell migration and proliferation. In addition to this pro-tumorigenic function, CD155 plays an immunomodulatory role during tumor progression since it is a ligand for both the activating receptor DNAM-1 and the inhibitory receptor TIGIT, expressed on cytotoxic innate and adaptative lymphocytes. DNAM-1 is a well-recognized receptor involved in anti-tumor immune surveillance. However, in advanced tumor stages, TIGIT is up-regulated and acts as an immune checkpoint receptor, counterbalancing DNAM-1-mediated cancer cell clearance. Pre-clinical studies have proposed the direct targeting of CD155 on tumor cells as well as the enhancement of DNAM-1-mediated anti-tumor functions as promising therapeutic approaches. Moreover, immunotherapeutic use of anti-TIGIT blocking antibody alone or in combined therapy has already been included in clinical trials. The aim of this review is to summarize all these potential therapies, highlighting the still controversial role of CD155 during tumor progression.

Immune checkpoints targeting dendritic cells for antibody-based modulation in cancer

Dendritic cells (DC) are professional antigen-presenting cells which link innate to adaptive immunity. DC play a central role in regulating antitumor T-cell responses in both tumor-draining lymph nodes (TDLN) and the tumor microenvironment (TME). They modulate effector T-cell responses via immune checkpoint proteins (ICPs) that can be either stimulatory or inhibitory. Functions of DC are often impaired by the suppressive TME leading to tumor immune escape. Therefore, better understanding of the mechanisms of action of ICPs expressed by (tumor-infiltrating) DC will lead to potential new treatment strategies. Genetic manipulation and high-dimensional analyses have provided insight in the interactions between DC and T-cells in TDLN and the TME upon ICP targeting. In this review, we discuss (tumor-infiltrating) DC lineage cells and tumor tissue specific "mature" DC states and their gene signatures in relation to anti-tumor immunity. We also review a number of ICPs expressed by DC regarding their functions in phagocytosis, DC activation, or inhibition and outline position in, or promise for clinical trials in cancer immunotherapy. Collectively, we highlight the critical role of DC and their exact status in the TME for the induction and propagation of T-cell immunity to cancer.

Current advances in immunotherapy for atypical teratoid rhabdoid tumor (ATRT)

Atypical teratoid rhabdoid tumors (ATRT) are rare and aggressive embryonal tumors of central nervous system that typically affect children younger than 3 years of age. Given the generally poor outcomes of patients with ATRT and the significant toxicities associated with conventional multi-modal therapies, there is an urgent need for more novel approaches to treat ATRT, one such approach being immunotherapy. The recent rise of large-scale, multicenter interdisciplinary studies has delineated several molecular and genetic characteristics unique to ATRT. This review aims to describe currently available data on the tumor immune microenvironment of ATRT and its specific subtypes and to summarize the emerging clinical and preclinical results of immunotherapy-based approaches. It will also highlight the evolving knowledge of epigenetics on immunomodulation in this epigenetically influenced tumor, which may help guide the development of effective immunotherapeutic approaches in the future.

Clinical Applications of Immunotherapy for Recurrent Glioblastoma in Adults

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults. Despite standard therapies, including resection and chemoradiation, recurrence is virtually inevitable. Current treatment for recurrent glioblastoma (rGBM) is rapidly evolving, and emerging therapies aimed at targeting primary GBM are often first tested in rGBM to demonstrate safety and feasibility, which, in recent years, has primarily been in the form of immunotherapy. The purpose of this review is to highlight progress in clinical trials of immunotherapy for rGBM, including immune checkpoint blockade, oncolytic virotherapy, chimeric antigen receptor (CAR) T-cell therapy, cancer vaccine and immunotoxins. Three independent reviewers covered literature, published between the years 2000 and 2022, in various online databases. In general, the efficacy of immunotherapy in rGBM remains uncertain, and is limited to subsets/small cohorts of patients, despite demonstrating feasibility in early-stage clinical trials. However, considerable progress has been made in understanding the mechanisms that may preclude rGBM patients from responding to immunotherapy, as well as in developing new approaches/combination strategies that may inspire optimism for the utility of immunotherapy in this devastating disease. Continued trials are necessary to further assess the best therapeutic avenues and ascertain which treatments might benefit each patient individually.

Oncolytic virotherapy evolved into the fourth generation as tumor immunotherapy

BACKGROUND

Oncolytic virotherapy (OVT) is a promising anti-tumor modality that utilizes oncolytic viruses (OVs) to preferentially attack cancers rather than normal tissues. With the understanding particularly in the characteristics of viruses and tumor cells, numerous innovative OVs have been engineered to conquer cancers, such as Talimogene Laherparepvec (T-VEC) and tasadenoturev (DNX-2401). However, the therapeutic safety and efficacy must be further optimized and balanced to ensure the superior safe and efficient OVT in clinics, and reasonable combination therapy strategies are also important challenges worthy to be explored.

MAIN BODY

Here we provided a critical review of the development history and status of OVT, emphasizing the mechanisms of enhancing both safety and efficacy. We propose that oncolytic virotherapy has evolved into the fourth generation as tumor immunotherapy. Particularly, to arouse T cells by designing OVs expressing bi-specific T cell activator (BiTA) is a promising strategy of killing two birds with one stone. Amazing combination of therapeutic strategies of OVs and immune cells confers immense potential for managing cancers. Moreover, the attractive preclinical OVT addressed recently, and the OVT in clinical trials were systematically reviewed.

CONCLUSION

OVs, which are advancing into clinical trials, are being envisioned as the frontier clinical anti-tumor agents coming soon.

Recombinant polio-rhinovirus immunotherapy for recurrent paediatric high-grade glioma: a phase 1b trial

BACKGROUND

Outcomes of recurrent paediatric high-grade glioma are poor, with a median overall survival of less than 6 months. Viral immunotherapy, such as the polio-rhinovirus chimera lerapolturev, is a novel approach for treatment of recurrent paediatric high-grade glioma and has shown promise in adults with recurrent glioblastoma. The poliovirus receptor CD155 is ubiquitously expressed in malignant paediatric brain tumours and is a treatment target in paediatric high-grade glioma. We aimed to assess the safety of lerapolturev when administered as a single dose intracerebrally by convection enhanced delivery in children and young people with recurrent WHO grade 3 or grade 4 glioma, and to assess overall survival in these patients.

METHODS

This phase 1b trial was done at the Duke University Medical Center (Durham, NC, USA). Patients aged 4-21 years with recurrent high-grade malignant glioma (anaplastic astrocytoma, glioblastoma, anaplastic oligoastrocytoma, anaplastic oligodendroglioma, or anaplastic pleomorphic xanthoastrocytoma) or anaplastic ependymoma, atypical teratoid rhabdoid tumour, or medulloblastoma with infusible disease were eligible for this study. A catheter was tunnelled beneath the scalp for a distance of at least 5 cm to aid in prevention of infection. The next day, lerapolturev at a dose of 5 × 107 median tissue culture infectious dose in 3 mL infusate loaded in a syringe was administered via a pump at a rate of 0·5 mL per h as a one-time dose. The infusion time was approximately 6·5 h to compensate for volume of the tubing. The primary endpoint was the proportion of patients with unacceptable toxic effects during the 14-day period after lerapolturev treatment. The study is registered with ClinicalTrials.gov, NCT03043391.

FINDINGS

Between Dec 5, 2017, and May 12, 2021, 12 patients (11 unique patients) were enrolled in the trial. Eight patients were treated with lerapolturev. The median patient age was 16·5 years (IQR 11·0-18·0), five (63%) of eight patients were male and three (38%) were female, and six (75%) of eight patients were White and two (25%) were Black or African American. The median number of previous chemotherapeutic regimens was 3·50 (IQR 1·25-5·00). Six of eight patients had 26 treatment-related adverse events attributable to lerapolturev. There were no irreversible (ie, persisted longer than 2 weeks) treatment-related grade 4 adverse events or deaths. Treatment-related grade 3 adverse events included headaches in two patients and seizure in one patient. Four patients received low-dose bevacizumab on-study for treatment-related peritumoural inflammation or oedema, diagnosed by both clinical symptoms plus fluid-attenuated inversion recovery MRI. The median overall survival was 4·1 months (95% CI 1·2-10·1). One patient remains alive after 22 months.

INTERPRETATION

Convection enhanced delivery of lerapolturev is safe enough in the treatment of recurrent paediatric high-grade glioma to proceed to the next phase of trial.

FUNDING

Solving Kids Cancer, B+ Foundation, Musella Foundation, and National Institutes of Health.

Intrinsic Immunogenic Tumor Cell Death Subtypes Delineate Prognosis and Responsiveness to Immunotherapy in Lung Adenocarcinoma

Recent studies have highlighted the combination of activation of host immunogenic cell death (ICD) and tumor-directed cytotoxic strategies. However, overall multiomic analysis of the intrinsic ICD property in lung adenocarcinoma (LUAD) has not been performed. Therefore, the aim of this study was to develop an ICD-based risk scoring system to predict overall survival (OS) and immunotherapeutic efficacy in patients. In our study, both weighted gene co-expression network analysis (WGCNA) and LASSO-Cox analysis were utilized to identify ICDrisk subtypes (ICDrisk). Moreover, we identify genomic alterations and differences in biological processes, analyze the immune microenvironment, and predict the response to immunotherapy in patients with pan-cancer. Importantly, immunogenicity subgroup typing was performed based on the immune score (IS) and microenvironmental tumor neoantigens (meTNAs). Our results demonstrate that ICDrisk subtypes were identified based on 16 genes. Furthermore, high ICDrisk was proved to be a poor prognostic factor in LUAD patients and indicated poor efficacy of immune checkpoint inhibitor (ICI) treatment in patients with pan-cancer. The two ICDrisk subtypes displayed distinct clinicopathologic features, tumor-infiltrating immune cell patterns, and biological processes. The IS^lowmeTNA^high subtype showed low intratumoral heterogeneity (ITH) and immune-activated phenotypes and correlated with better survival than the other subtypes within the high ICDrisk group. This study suggests effective biomarkers for the prediction of OS in LUAD patients and immunotherapeutic response across Pan-cancer and contributes to enhancing our understanding of intrinsic immunogenic tumor cell death.

Current Status and Challenges of Oncolytic Virotherapy for the Treatment of Glioblastoma

Despite decades of research and numerous clinical trials, the prognosis of patients diagnosed with glioblastoma (GBM) remains dire with median observed survival at 8 months. There is a critical need for novel treatments for GBM, which is the most common malignant primary brain tumor. Major advances in cancer therapeutics such as immune checkpoint inhibitors and chimeric antigen receptor (CAR) T-cell therapy have not yet led to improved outcomes for GBM. Conventional therapy of surgery followed by chemoradiation with or without tumor treating fields remains the standard of care. One of the many approaches to GBM therapy currently being explored is viral therapies. These typically work by selectively lysing target neoplastic cells, called oncolysis, or by the targeted delivery of a therapeutic transgene via a viral vector. In this review, we discuss the underlying mechanisms of action and describe both recent and current human clinical trials using these viruses with an emphasis on promising viral therapeutics that may ultimately break the field's current stagnant paradigm.

Updates in Glioblastoma Immunotherapy: An Overview of the Current Clinical and Translational Scenario

Glioblastoma (GBM) is the most common and aggressive central nervous system tumor, requiring multimodal management. Due to its malignant behavior and infiltrative growth pattern, GBM is one of the most difficult tumors to treat and gross total resection is still considered to be the first crucial step. The deep understanding of GBM microenvironment and the possibility of manipulating the patient's innate and adaptive immune system to fight the neoplasm represent the base of immunotherapeutic strategies that currently express the future for the fight against GBM. Despite the immunotherapeutic approach having been successfully adopted in several solid and haematologic neoplasms, immune resistance and the immunosuppressive environment make the use of these strategies challenging in GBM treatment. We describe the most recent updates regarding new therapeutic strategies that target the immune system, immune checkpoint inhibitors, chimeric antigen receptor T cell therapy, peptide and oncolytic vaccines, and the relevant mechanism of immune resistance. However, no significant results have yet been obtained in studies targeting single molecules/pathways. The future direction of GBM therapy will include a combined approach that, in contrast to the inescapable current treatment modality of maximal resection followed by chemo- and radiotherapy, may combine a multifaceted immunotherapy treatment with the dual goals of directly killing tumor cells and activating the innate and adaptive immune response.

A combination of genetically engineered oncolytic virus and melittin-CpG for cancer viro-chemo-immunotherapy

BACKGROUND

Immunotherapy has emerged as an efficient therapeutic approach for cancer management. However, stimulation of host immune system against cancer cells often fails to achieve promising clinical outcomes mainly owing to the immunosuppressive characteristics of the tumor microenvironment (TME). Combination therapeutics that can trigger sustained immunogenic cell death (ICD) have provided new opportunities for cancer treatment.

METHODS

In this study, we designed and applied an ICD inducer regimen, including a genetically engineered oncolytic virus (miRNA-modified coxsackieviruses B3, miR-CVB3), a pore-forming lytic peptide (melittin, found in bee venom), and a synthetic toll-like receptor 9 ligand (CpG oligodeoxynucleotides), for breast cancer and melanoma treatment. We compared the anti-tumor efficacy of miR-CVB3 and CpG-melittin (CpGMel) alone and in combination (miR-CVB3 + CpGMel) and investigated possible mechanisms involved.

RESULTS

We demonstrated that miR-CVB3 + CpGMel had no major impact on viral growth, while enhancing the cellular uptake of CpGMel in vitro. We further showed that combination therapy led to significant increases in tumor cell death and release of damage-associated molecular patterns compared with individual treatment. In vivo studies in 4T1 tumor-bearing Balb/c mice revealed that both primary and distant tumors were significantly suppressed, and the survival rate was significantly prolonged after administration of miR-CVB3 + CpGMel compared with single treatment. This anti-tumor effect was accompanied by increased ICD and immune cell infiltration into the TME. Safety analysis showed no significant pathological abnormalities in Balb/c mice. Furthermore, the developed therapeutic regimen also demonstrated a great anti-tumor activity in B16F10 melanoma tumor-bearing C57BL/6 J mice.

CONCLUSIONS

Overall, our findings indicate that although single treatment using miR-CVB3 or CpGMel can efficiently delay tumor growth, combining oncolytic virus-based therapy can generate even stronger anti-tumor immunity, leading to a greater reduction in tumor size.

Oncolytic virotherapy: basic principles, recent advances and future directions

Oncolytic viruses (OVs) have attracted growing awareness in the twenty-first century, as they are generally considered to have direct oncolysis and cancer immune effects. With the progress in genetic engineering technology, OVs have been adopted as versatile platforms for developing novel antitumor strategies, used alone or in combination with other therapies. Recent studies have yielded eye-catching results that delineate the promising clinical outcomes that OVs would bring about in the future. In this review, we summarized the basic principles of OVs in terms of their classifications, as well as the recent advances in OV-modification strategies based on their characteristics, biofunctions, and cancer hallmarks. Candidate OVs are expected to be designed as "qualified soldiers" first by improving target fidelity and safety, and then equipped with "cold weapons" for a proper cytocidal effect, "hot weapons" capable of activating cancer immunotherapy, or "auxiliary weapons" by harnessing tactics such as anti-angiogenesis, reversed metabolic reprogramming and decomposing extracellular matrix around tumors. Combinations with other cancer therapeutic agents have also been elaborated to show encouraging antitumor effects. Robust results from clinical trials using OV as a treatment congruously suggested its significance in future application directions and challenges in developing OVs as novel weapons for tactical decisions in cancer treatment.

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

BACKGROUND

Antitumor mechanisms of CD4⁺ T cells remain crudely defined, and means to effectively harness CD4⁺ T-cell help for cancer immunotherapy are lacking. Pre-existing memory CD4⁺ T cells hold potential to be leveraged for this purpose. Moreover, the role of pre-existing immunity in virotherapy, particularly recombinant poliovirus immunotherapy where childhood polio vaccine specific immunity is ubiquitous, remains unclear. Here we tested the hypothesis that childhood vaccine-specific memory T cells mediate antitumor immunotherapy and contribute to the antitumor efficacy of polio virotherapy.

METHODS

The impact of polio immunization on polio virotherapy, and the antitumor effects of polio and tetanus recall were tested in syngeneic murine melanoma and breast cancer models. CD8⁺ T-cell and B-cell knockout, CD4⁺ T-cell depletion, CD4⁺ T-cell adoptive transfer, CD40L blockade, assessments of antitumor T-cell immunity, and eosinophil depletion defined antitumor mechanisms of recall antigens. Pan-cancer transcriptome data sets and polio virotherapy clinical trial correlates were used to assess the relevance of these findings in humans.

RESULTS

Prior vaccination against poliovirus substantially bolstered the antitumor efficacy of polio virotherapy in mice, and intratumor recall of poliovirus or tetanus immunity delayed tumor growth. Intratumor recall antigens augmented antitumor T-cell function, caused marked tumor infiltration of type 2 innate lymphoid cells and eosinophils, and decreased proportions of regulatory T cells (Tregs). Antitumor effects of recall antigens were mediated by CD4⁺ T cells, limited by B cells, independent of CD40L, and dependent on eosinophils and CD8⁺ T cells. An inverse relationship between eosinophil and Treg signatures was observed across The Cancer Genome Atlas (TCGA) cancer types, and eosinophil depletion prevented Treg reductions after polio recall. Pretreatment polio neutralizing antibody titers were higher in patients living longer, and eosinophil levels increased in the majority of patients, after polio virotherapy.

CONCLUSION

Pre-existing anti-polio immunity contributes to the antitumor efficacy of polio virotherapy. This work defines cancer immunotherapy potential of childhood vaccines, reveals their utility to engage CD4⁺ T-cell help for antitumor CD8⁺ T cells, and implicates eosinophils as antitumor effectors of CD4⁺ T cells.

Attenuated WNV-poly(A) exerts a broad-spectrum oncolytic effect by selective virus replication and CD8+ T cell-dependent immune response

As an emerging tumor therapy, ideal oncolytic viruses preferentially replicate in malignant cells, reverse the immunosuppressive tumor microenvironment, and eventually can be eliminated by the patient. It is of great significance for cancer treatment to discover new excellent oncolytic viruses. Here, we found that WNV live attenuated vaccine WNV-poly(A) could be developed as a novel ideal oncolytic agent against several types of cancers. Mechanistically, due to its high sensitivity to type Ι interferon (IFN-Ι), WNV-poly(A) could specifically kill tumor cells rather than normal cells. At the same time, WNV-poly(A) could activate Dendritic cells (DCs) and trigger tumor antigen specific response mediated by CD8 + T cell, which contributed to inhibit the propagation of original and distal tumor cells. Like intratumoral injection, intravenous injection with WNV-poly(A) also markedly delays Huh7 hepatic carcinoma (HCC) transplanted tumor progression. Most importantly, in addition to an array of mouse xenograft tumor models, WNV-poly(A) also has a significant inhibitory effect on many different types of patient-derived tumor tissues and HCC patient-derived xenograft (PDX) tumor models. Our studies reveal that WNV-poly(A) is a potent and excellent oncolytic agent against many types of tumors and may have a role in metastatic and recurrent tumors.

Immunogenic cell death: The cornerstone of oncolytic viro-immunotherapy

According to the World Health Organization, cancer is one of the leading global health concerns, causing nearly 10 million deaths in 2020. While classical chemotherapeutics produce strong cytotoxicity on cancer cells, they carry limitations of drug resistance and off-target effects and sometimes fail to elicit adequate antitumor protection against tumor relapse. Additionally, most cancer cells have developed various ways to escape immune surveillance. Nevertheless, novel anticancer strategies such as oncolytic viro-immunotherapy can trigger immunogenic cell death (ICD), which can quickly grasp the attention of the host defense machinery, resulting in an ensuing antitumor immune response. Specifically, oncolytic viruses (OVs) can infect and destroy targeted cancer cells and stimulate the immune system by exposing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) to promote inflammatory reactions, and concomitantly prime and induce antitumor immunity by the release of neoantigens from the damaged cancer cells. Thus, OVs can serve as a novel system to sensitize tumor cells for promising immunotherapies. This review discusses the concept of ICD in cancer, centralizing ICD-associated danger signals and their consequence in antitumor responses and ICD induced by OVs. We also shed light on the potential strategies to enhance the immunogenicity of OVs, including the use of genetically modified OVs and their combination with ICD-enhancing agents, which are helpful as forthcoming anticancer regimens.

Chemotherapeutic and targeted drugs-induced immunogenic cell death in cancer models and antitumor therapy: An update review

As traditional strategies for cancer treatment, some chemotherapy agents, such as doxorubicin, oxaliplatin, cyclophosphamide, bortezomib, and paclitaxel exert their anti-tumor effects by inducing immunogenic cell death (ICD) of tumor cells. ICD induces anti-tumor immunity through release of, or exposure to, damage-related molecular patterns (DAMPs), including high mobility group box 1 (HMGB1), calreticulin, adenosine triphosphate, and heat shock proteins. This leads to activation of tumor-specific immune responses, which can act in combination with the direct killing functions of chemotherapy drugs on cancer cells to further improve their curative effects. In this review, we highlight the molecular mechanisms underlying ICD, including those of several chemotherapeutic drugs in inducing DAMPs exposed during ICD to activate the immune system, as well as discussing the prospects for application and potential role of ICD in cancer immunotherapy, with the aim of providing valuable inspiration for future development of chemoimmunotherapy.

Hypoxia-responsive Immunostimulatory Nanomedicines Synergize with Checkpoint Blockade Immunotherapy for Potentiating Cancer Immunotherapy

Inducing cell death while simultaneously enhancing antitumor immune responses is a promising therapeutic approach for multiple cancers. Celastrol (Cel) and 7-ethyl-10-hydroxycamptothecin (SN38) have contrasting physicochemical properties, but strong synergy in immunogenic cell death induction and anticancer activity. Herein, a hypoxia-sensitive nanosystem (CS@TAP) was designed to demonstrate effective immunotherapy for colorectal cancer by systemic delivery of an immunostimulatory chemotherapy combination. Furthermore, the combination of CS@TAP with anti-PD-L1 mAb (αPD-L1) exhibited a significant therapeutic benefit of delaying tumor growth and increased local doses of immunogenic signaling and T-cell infiltration, ultimately extending survival. We conclude that CS@TAP is an effective inducer of immunogenic cell death (ICD) in cancer immunotherapy. Therefore, this study provides an encouraging strategy to synergistically induce immunogenic cell death to enhance tumor cytotoxic T lymphocytes (CTLs) infiltration for anticancer immunotherapy.

SARS-CoV-2 replicates and displays oncolytic properties in clear cell and papillary renal cell carcinoma

The SARS-CoV-2 virus is currently causing a global pandemic. Infection may result in a systemic disease called COVID-19, affecting primarily the respiratory tract. Often the gastrointestinal tract and kidneys also become involved. Angiotensin converting enzyme 2 (ACE2) serves as the receptor for SARS-CoV-2. The membrane proteins, Transmembrane serine protease 2 (TMPRSS2) and Neuropilin 1 (NRP1) are accessory proteins facilitating the virus entry. In this study we show that the human proximal kidney tubules, express these factors. We hypothesized that cancers derived from proximal tubules as clear cell (CCRCC) and papillary renal cell carcinoma (PRCC), retain the expression of the SARS-CoV-2 entry factors making these cancers susceptible to SARS-CoV-2 infection. We used bioinformatics, western blotting, and assessment of tissue micro arrays (TMA) including 263 cases of CCRCC, 139 cases of PRCC and 18 cases of chromophobe RCC to demonstrate that the majority of CCRCC and PRCC cases retained the RNA and protein expression of the entry factors for SARS-CoV-2. We furthermore show that SARS-CoV-2 virus propagated robustly in primary cultures of CCRCC and PRCC cells with a visible virus cytopathogenic effect correlating with viral RNA expression levels. We also noted that the delta-variant of SARS-CoV-2 causes cancer cells to form syncytia in-vitro. This phenomenon was also identified histologically in CCRCC tissue from a patient that had been hospitalized for COVID-19, twelve months prior to nephrectomy. Our data provide insights into SARS-CoV-2 infectivity in renal cell carcinoma and that the virus causes a distinct cytopathogenic effect.

Hypoxia-responsive Immunostimulatory Nanomedicines Synergize with Checkpoint Blockade Immunotherapy for Potentiating Cancer Immunotherapy

Inducing cell death while simultaneously enhancing antitumor immune responses is a promising therapeutic approach for multiple cancers. Celastrol (Cel) and 7-ethyl-10-hydroxycamptothecin (SN38) have contrasting physicochemical properties, but strong synergy in immunogenic cell death induction and anticancer activity. Herein, a hypoxia-sensitive nanosystem (CS@TAP) was designed to demonstrate effective immunotherapy for colorectal cancer by systemic delivery of an immunostimulatory chemotherapy combination. Furthermore, the combination of CS@TAP with anti-PD-L1 mAb (αPD-L1) exhibited a significant therapeutic benefit of delaying tumor growth and increased local doses of immunogenic signaling and T-cell infiltration, ultimately extending survival. We conclude that CS@TAP is an effective inducer of immunogenic cell death (ICD) in cancer immunotherapy. Therefore, this study provides an encouraging strategy to synergistically induce immunogenic cell death to enhance tumor cytotoxic T lymphocytes (CTLs) infiltration for anticancer immunotherapy.

Convection-enhanced delivery of immunomodulatory therapy for high-grade glioma

The prognosis for glioblastoma has remained poor despite multimodal standard of care treatment, including temozolomide, radiation, and surgical resection. Further, the addition of immunotherapies, while promising in a number of other solid tumors, has overwhelmingly failed in the treatment of gliomas, in part due to the immunosuppressive microenvironment and poor drug penetrance to the brain. Local delivery of immunomodulatory therapies circumvents some of these challenges and has led to long-term remission in select patients. Many of these approaches utilize convection-enhanced delivery (CED) for immunological drug delivery, allowing high doses to be delivered directly to the brain parenchyma, avoiding systemic toxicity. Here, we review the literature encompassing immunotherapies delivered via CED-from preclinical model systems to clinical trials-and explore how their unique combination elicits an antitumor response by the immune system, decreases toxicity, and improves survival among select high-grade glioma patients.

Expanding cross-presenting dendritic cells enhances oncolytic virotherapy and is critical for long-term anti-tumor immunity

Immunotherapies directly enhancing anti-tumor CD8+ T cell responses have yielded measurable but limited success, highlighting the need for alternatives. Anti-tumor T cell responses critically depend on antigen presenting dendritic cells (DC), and enhancing mobilization, antigen loading and activation of these cells represent an attractive possibility to potentiate T cell based therapies. Here we show that expansion of DCs by Flt3L administration impacts in situ vaccination with oncolytic Newcastle Disease Virus (NDV). Mechanistically, NDV activates DCs and sensitizes them to dying tumor cells through upregulation of dead-cell receptors and synergizes with Flt3L to promote anti-tumor CD8+ T cell cross-priming. In vivo, Flt3L-NDV in situ vaccination induces parallel amplification of virus- and tumor-specific T cells, including CD8+ T cells reactive to newly-described neoepitopes, promoting long-term tumor control. Cross-presenting conventional Type 1 DCs are indispensable for the anti-tumor, but not anti-viral, T cell response, and type I IFN-dependent CD4+ Th1 effector cells contribute to optimal anti-tumor immunity. These data demonstrate that mobilizing DCs to increase tumor antigen cross-presentation improves oncolytic virotherapy and that neoepitope-specific T cells can be induced without individualized, ex vivo manufactured vaccines.

Current landscape and perspective of oncolytic viruses and their combination therapies

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Oncolytic virotherapy has become an important branch of cancer immunotherapy in clinical practice.

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Multiple viruses can be engineered to be OVs and armed with anticancer genes to enhance their efficacy.

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OVs can reshape TME and produce synergistic anticancer efficacy when combined with other therapies.

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Safety and effectiveness are the main direction of future research and development of OVs.

Oncolytic virotherapy has become an important strategy in cancer immunotherapy. Oncolytic virus (OV) can reshape the tumor microenvironment (TME) through its replication-mediated oncolysis and transgene-produced anticancer effect, inducing an antitumor immune response and creating favorable conditions for the combination of other therapeutic measures. Extensive preclinical and clinical data have suggested that OV-based combination therapy has definite efficacy and promising prospects. Recently, several clinical trials of oncolytic virotherapy combined with immunotherapy have made breakthroughs. This review comprehensively elaborates the OV types and their targeting mechanisms, the selection of anticancer genes armed in OVs, and the therapeutic modes of action and strategies of OVs to provide a theoretical basis for the better design and construction of OVs and the optimization of OV-based therapeutic strategies.

Oncolyic Virotherapy for Prostate Cancer: Lighting a Fire in Winter

As the most common cancer of the genitourinary system, prostate cancer (PCa) is a global men's health problem whose treatments are an urgent research issue. Treatment options for PCa include active surveillance (AS), surgery, endocrine therapy, chemotherapy, radiation therapy, immunotherapy, etc. However, as the cancer progresses, the effectiveness of treatment options gradually decreases, especially in metastatic castration-resistant prostate cancer (mCRPC), for which there are fewer therapeutic options and which have a shorter survival period and worse prognosis. For this reason, oncolytic viral therapy (PV), with its exceptional properties of selective tumor killing, relatively good safety in humans, and potential for transgenic delivery, has attracted increasing attention as a new form of anti-tumor strategy for PCa. There is growing evidence that OV not only kills tumor cells directly by lysis but can also activate anticancer immunity by acting on the tumor microenvironment (TME), thereby preventing tumor growth. In fact, evidence of the efficacy of this strategy has been observed since the late 19th century. However, subsequently, interest waned. The renewed interest in this therapy was due to advances in biotechnological methods and innovations at the end of the 20th century, which was also the beginning of PCa therapy with OV. Moreover, in combination with chemotherapy, radiotherapy, gene therapy or immunotherapy, OV viruses can have a wide range of applications and can provide an effective therapeutic result in the treatment of PCa.

Multimodality analysis confers a prognostic benefit of a T-cell infiltrated tumor microenvironment and peripheral immune status in patients with melanoma

Background

We previously reported results from a phase 1 study testing intratumoral recombinant poliovirus, lerapolturev, in 12 melanoma patients. All 12 patients received anti-PD-1 systemic therapy before lerapolturev, and 11 of these 12 patients also received anti-PD-1 after lerapolturev. In preclinical models lerapolturev induces intratumoral innate inflammation that engages antitumor T cells. In the current study, prelerapolturev and postlerapolturev tumor biopsies and blood were evaluated for biomarkers of response.

Methods

The following analyses were performed on tumor tissue (n=11): (1) flow cytometric assessment of immune cell density, (2) NanoString Digital Spatial profiling of protein and the transcriptome, and (3) bulk RNA sequencing. Immune cell phenotypes and responsiveness to in vitro stimulation, including in vitro lerapolturev challenge, were measured in peripheral blood (n=12).

Results

Three patients who received anti-PD-1 therapy within 30 days of lerapolturev have a current median progression-free survival (PFS) of 2.3 years and had higher CD8+T cell infiltrates in prelerapolturev tumor biopsies relative to that of 7 patients with median PFS of 1.6 months and lower CD8+T cell infiltrates in prelerapolturev tumor biopsies. In peripheral blood, four patients with PFS 2.3 years (including three that received anti-PD-1 therapy within 30 days before lerapolturev and had higher pretreatment tumor CD8+T cell infiltrates) had significantly higher effector memory (CD8+, CCR7-, CD45RA-) but lower CD8+PD-1+ and CD4+PD-1+ cells compared with eight patients with median PFS 1.6 months. In addition, pretreatment blood from the four patients with median PFS 2.3 years had more potent antiviral responses to in vitro lerapolturev challenge compared with eight patients with median PFS 1.6 months.

Conclusion

An inflamed pretreatment tumor microenvironment, possibly induced by prior anti-PD-1 therapy and a proficient peripheral blood pretreatment innate immune response (antiviral/interferon signaling) to lerapolturev was associated with long term PFS after intratumoral lerapolturev in a small cohort of patients. These findings imply a link between intratumoral T cell inflammation and peripheral immune function.

Trial registration number

NCT03712358.

Current clinical landscape of oncolytic viruses as novel cancer immunotherapeutic and recent preclinical advancements

Oncolytic viruses (OVs) have been gaining attention in the pharmaceutical industry as a novel immunotherapeutic and therapeutic adjuvant due to their ability to induce and boost antitumor immunity through multiple mechanisms. First, intrinsic mechanisms of OVs that enable exploitation of the host immune system (e.g., evading immune detection) can nullify the immune escape mechanism of tumors. Second, many types of OVs have been shown to cause direct lysis of tumor cells, resulting in an induction of tumor-specific T cell response mediated by release of tumor-associated antigens and danger signal molecules. Third, armed OV-expressing immune stimulatory therapeutic genes could be highly expressed in tumor tissues to further improve antitumor immunity. Last, these OVs can inflame cold tumors and their microenvironment to be more immunologically favorable for other immunotherapeutics. Due to these unique characteristics, OVs have been tested as an adjuvant of choice in a variety of therapeutics. In light of these promising attributes of OVs in the immune-oncology field, the present review will examine OVs in clinical development and discuss various strategies that are being explored in preclinical stages for the next generation of OVs that are optimized for immunotherapy applications.

Preinduced reovirus-specific T-cell immunity enhances the anticancer efficacy of reovirus therapy

BACKGROUND

Many solid tumors do not respond to immunotherapy due to their immunologically cold tumor microenvironment (TME). We and others found that oncolytic viruses (OVs), including reovirus type 3 Dearing, can enhance the efficacy of immunotherapy by recruiting CD8⁺ T cells to the TME. A significant part of the incoming CD8⁺ T cells is directed toward reovirus itself, which may be detrimental to the efficacy of OVs. However, here we aim to exploit these incoming virus-specific T cells as anticancer effector cells.

METHODS

We performed an in-depth characterization of the reovirus-induced T-cell response in immune-competent mice bearing pancreatic KPC3 tumors. The immunodominant CD8⁺ T-cell epitope of reovirus was identified using epitope prediction algorithms and peptide arrays, and the quantity and quality of reovirus-specific T cells after reovirus administration were assessed using high-dimensional flow cytometry. A synthetic long peptide (SLP)-based vaccination strategy was designed to enhance the intratumoral frequency of reovirus-specific CD8⁺ T cells.

RESULTS

Reovirus administration did not induce tumor-specific T cells but rather induced high frequencies of reovirus-specific CD8⁺ T cells directed to the immunodominant epitope. Priming of reovirus-specific T cells required a low-frequent population of cross-presenting dendritic cells which was absent in Batf3^-/- mice. While intratumoral and intravenous reovirus administration induced equal systemic frequencies of reovirus-specific T cells, reovirus-specific T cells were highly enriched in the TME exclusively after intratumoral administration. Here, they displayed characteristics of potent effector cells with high expression of KLRG1, suggesting they may be responsive against local reovirus-infected cells. To exploit these reovirus-specific T cells as anticancer effector cells, we designed an SLP-based vaccination strategy to induce a strong T-cell response before virotherapy. These high frequencies of circulating reovirus-specific T cells were reactivated on intratumoral reovirus administration and significantly delayed tumor growth.

CONCLUSIONS

These findings provide proof of concept that OV-specific T cells, despite not being tumor-specific, can be exploited as potent effector cells for anticancer treatment when primed before virotherapy. This is an attractive strategy for low-immunogenic tumors lacking tumor-specific T cells.

PKR Binds Enterovirus IRESs, Displaces Host Translation Factors, and Impairs Viral Translation to Enable Innate Antiviral Signaling

For RNA virus families except Picornaviridae, viral RNA sensing includes Toll-like receptors and/or RIG-I. Picornavirus RNAs, whose 5' termini are shielded by a genome-linked protein, are predominately recognized by MDA5. This has important ramifications for adaptive immunity, as MDA5-specific patterns of type-I interferon (IFN) release are optimal for CD4+T cell TH1 polarization and CD8+T cell priming. We are exploiting this principle for cancer immunotherapy with recombinant poliovirus (PV), PVSRIPO, the type 1 (Sabin) PV vaccine containing a rhinovirus type 2 internal ribosomal entry site (IRES). Here we show that PVSRIPO-elicited MDA5 signaling is preceded by early sensing of the IRES by the double-stranded (ds)RNA-activated protein kinase (PKR). PKR binding to IRES stem-loop domains 5-6 led to dimerization and autoactivation, displaced host translation initiation factors, and suppressed viral protein synthesis. Early PKR-mediated antiviral responses tempered incipient viral translation and the activity of cytopathogenic viral proteinases, setting up accentuated MDA5 innate inflammation in response to PVSRIPO infection. IMPORTANCE Among the RIG-I-like pattern recognition receptors, MDA5 stands out because it senses long dsRNA duplexes independent of their 5' features (RIG-I recognizes viral [v]RNA 5'-ppp blunt ends). Uniquely among RNA viruses, the innate defense against picornaviruses is controlled by MDA5. We show that prior to engaging MDA5, recombinant PV RNA is sensed upon PKR binding to the viral IRES at a site that overlaps with the footprint for host translation factors mediating 40S subunit recruitment. Our study demonstrates that innate antiviral type-I IFN responses orchestrated by MDA5 involve separate innate modules that recognize distinct vRNA features and interfere with viral functions at multiple levels.

Remission of Liquid Tumors and SARS-CoV-2 Infection: a Literature Review

The coronavirus disease 2019 (COVID-19) pandemic has produced a new global challenge for patients with cancer. The disease and the immunosuppression induced by cancer therapies have generated a perfect storm of conditions to increase the severity of the symptoms and worsen the prognosis. However, a few clinical reports showcased the power of viruses to induce remission in some patients suffering from liquid tumors. Here, we reviewed six cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that resulted in cancer remission, simultaneously highlighting the strengths and the unique challenges of oncolytic virotherapy. Virotherapy has become a special case of cancer immunotherapy. This paradigm-shifting concept suggests that oncolytic viruses are not only promising agents to combat particularly immunologically suppressed, immunotherapy-resistant tumors but also that the trigger of local inflammation, such as SARS-CoV-2 infection of the respiratory pathways, may trigger an abscopal effect sufficient to induce the remission of systemic cancer.

Immunotherapy by mesenchymal stromal cell delivery of oncolytic viruses for treating metastatic tumors

Oncolytic viruses (OVs) have emerged as a very promising anti-cancer therapeutic strategy in the past decades. However, despite their pre-clinical promise, many OV clinical evaluations for cancer therapy have highlighted the continued need for their improved delivery and targeting. Mesenchymal stromal cells (MSCs) have emerged as excellent candidate vehicles for the delivery of OVs due to their tumor-homing properties and low immunogenicity. MSCs can enhance OV delivery by protecting viruses from rapid clearance following administration and also by more efficiently targeting tumor sites, consequently augmenting the therapeutic potential of OVs. MSCs can function as “biological factories,” enabling OV amplification within these cells to promote tumor lysis following MSC-OV arrival at the tumor site. MSC-OVs can promote enhanced safety profiles and therapeutic effects relative to OVs alone. In this review we explore the general characteristics of MSCs as delivery tools for cancer therapeutic agents. Furthermore, we discuss the potential of OVs as immune therapeutics and highlight some of the promising applications stemming from combining MSCs to achieve enhanced delivery and anti-tumor effectiveness of OVs at different pre-clinical and clinical stages. We further provide potential pitfalls of the MSC-OV platform and the strategies under development for enhancing the efficacy of these emerging therapeutics.