Novel oncolytic adenovirus expressing enhanced cross-hybrid IgGA Fc PD-L1 inhibitor activates multiple immune effector populations leading to enhanced tumor killing in vitro, in vivo and with patient-derived tumor organoids

Cancer organoids 2.0: modelling the complexity of the tumour immune microenvironment

The development of neoplasia involves a complex and continuous interplay between malignantly transformed cells and the tumour microenvironment (TME). Cancer immunotherapies targeting the immune TME have been increasingly validated in clinical trials but response rates vary substantially between tumour histologies and are often transient, idiosyncratic and confounded by resistance. Faithful experimental models of the patient-specific tumour immune microenvironment, capable of recapitulating tumour biology and immunotherapy effects, would greatly improve patient selection, target identification and definition of resistance mechanisms for immuno-oncology therapeutics. In this Review, we discuss currently available and rapidly evolving 3D tumour organoid models that capture important immune features of the TME. We highlight diverse opportunities for organoid-based investigations of tumour immunity, drug development and precision medicine.

Oncolytic virus V937 in combination with PD-1 blockade therapy to target immunologically quiescent liver and colorectal cancer

V937 is an investigational, genetically unmodified Kuykendall strain of coxsackievirus A21, which has been evaluated in the clinic for advanced solid tumor malignancies. V937 specifically infects and lyses tumor cells that overexpress intercellular adhesion molecule-1 (ICAM-1). Intratumoral V937 as a monotherapy and in combination with anti-PD-1 antibody pembrolizumab has shown clinical response in patients with metastatic melanoma, which overexpresses ICAM-1. Here, we investigate in preclinical studies the potential bidirectional cross-talk between hepatocellular carcinomas (HCC) or colorectal carcinomas (CRC) and immune cells when treated with V937 alone or in combination with pembrolizumab. We show that while V937 treatment of tumor cell lines or organoids or peripheral blood mononuclear cells (PBMCs) alone induced a minimal immunological response, V937 treatment of non-contact co-cultures of tumor cell lines or CRC organoids with PBMCs led to robust production of proinflammatory cytokines and immune cell activation. In addition, both recombinant interferon-gamma and pembrolizumab increased ICAM-1 on tumor cell lines or organoids and, in turn, amplified V937-mediated oncolysis and immunogenicity. These findings provide critical mechanistic insights on the cross-talk between V937-mediated oncolysis and immune responses, demonstrating the therapeutic potential of V937 in combination with PD-1 blockade to treat immunologically quiescent cancers.

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.

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.

Regulatory mechanisms of PD-1/PD-L1 in cancers

Immune evasion contributes to cancer growth and progression. Cancer cells have the ability to activate different immune checkpoint pathways that harbor immunosuppressive functions. The programmed death protein 1 (PD-1) and programmed cell death ligands (PD-Ls) are considered to be the major immune checkpoint molecules. The interaction of PD-1 and PD-L1 negatively regulates adaptive immune response mainly by inhibiting the activity of effector T cells while enhancing the function of immunosuppressive regulatory T cells (Tregs), largely contributing to the maintenance of immune homeostasis that prevents dysregulated immunity and harmful immune responses. However, cancer cells exploit the PD-1/PD-L1 axis to cause immune escape in cancer development and progression. Blockade of PD-1/PD-L1 by neutralizing antibodies restores T cells activity and enhances anti-tumor immunity, achieving remarkable success in cancer therapy. Therefore, the regulatory mechanisms of PD-1/PD-L1 in cancers have attracted an increasing attention. This article aims to provide a comprehensive review of the roles of the PD-1/PD-L1 signaling in human autoimmune diseases and cancers. We summarize all aspects of regulatory mechanisms underlying the expression and activity of PD-1 and PD-L1 in cancers, including genetic, epigenetic, post-transcriptional and post-translational regulatory mechanisms. In addition, we further summarize the progress in clinical research on the antitumor effects of targeting PD-1/PD-L1 antibodies alone and in combination with other therapeutic approaches, providing new strategies for finding new tumor markers and developing combined therapeutic approaches.

Harnessing adenovirus in cancer immunotherapy: evoking cellular immunity and targeting delivery in cell-specific manner

Recombinant adenovirus (rAd) regimens, including replication-competent oncolytic adenovirus (OAV) and replication-deficient adenovirus, have been identified as potential cancer therapeutics. OAV presents advantages such as selective replication, oncolytic efficacy, and tumor microenvironment (TME) remodeling. In this perspective, the principles and advancements in developing OAV toolkits are reviewed. The burgeoning rAd may dictate efficacy of conventional cancer therapies as well as cancer immunotherapies, including cancer vaccines, synergy with adoptive cell therapy (ACT), and TME reshaping. Concurrently, we explored the potential of rAd hitchhiking to adoptive immune cells or stem cells, highlighting how this approach facilitates synergistic interactions between rAd and cellular therapeutics at tumor sites. Results from preclinical and clinical trials in which immune and stem cells were infected with rAd have been used to address significant oncological challenges, such as postsurgical residual tumor tissue and metastatic tissue. Briefly, rAd can eradicate tumors through various mechanisms, resulting from tumor immunogenicity, reprogramming of the TME, enhancement of cellular immunity, and effective tumor targeting. In this context, we argue that rAd holds immense potential for enhancing cellular immunity and synergistically improving antitumor effects in combination with novel cancer immunotherapies.

Translational Aspects of Epithelioid Sarcoma: Current Consensus

Epithelioid sarcoma (EpS) is an ultra-rare malignant soft-tissue cancer mostly affecting adolescents and young adults. EpS often exhibits an unfavorable clinical course with fatal outcome in ∼50% of cases despite aggressive multimodal therapies combining surgery, chemotherapy, and irradiation. EpS is traditionally classified in a more common, less aggressive distal (classic) type and a rarer aggressive proximal type. Both subtypes are characterized by a loss of nuclear INI1 expression, most often following homozygous deletion of its encoding gene, SMARCB1-a core subunit of the SWI/SNF chromatin remodeling complex. In 2020, the EZH2 inhibitor tazemetostat was the first targeted therapy approved for EpS, raising new hopes. Still, the vast majority of patients did not benefit from this drug or relapsed rapidly. Further, other recent therapeutic modalities, including immunotherapy, are only effective in a fraction of patients. Thus, novel strategies, specifically targeted to EpS, are urgently needed. To accelerate translational research on EpS and eventually boost the discovery and development of new diagnostic tools and therapeutic options, a vibrant translational research community has formed in past years and held two international EpS digital expert meetings in 2021 and 2023. This review summarizes our current understanding of EpS from the translational research perspective and points to innovative research directions to address the most pressing questions in the field, as defined by expert consensus and patient advocacy groups.

Novel peptide-based oncolytic vaccine for enhancement of adaptive antitumor immune response via co-engagement of innate Fcγ and Fcα receptors

BACKGROUND

Cancer immunotherapy relies on using the immune system to recognize and eradicate cancer cells. Adaptive immunity, which consists of mainly antigen-specific cytotoxic T cells, plays a pivotal role in controlling cancer progression. However, innate immunity is a necessary component of the cancer immune response to support an immunomodulatory state, enabling T-cell immunosurveillance.

METHODS

Here, we elucidated and exploited innate immune cells to sustain the generation of antigen-specific T cells on the use of our cancer vaccine platform. We explored a previously developed oncolytic adenovirus (AdCab) encoding for a PD-L1 (Programmed-Death Ligand 1) checkpoint inhibitor, which consists of a PD-1 (Programmed Cell Death Protein 1) ectodomain fused to an IgG/A cross-hybrid Fc. We coated AdCab with major histocompatibility complex (MHC-I)-restricted tumor peptides, generating a vaccine platform (named PeptiCab); the latter takes advantage of viral immunogenicity, peptide cancer specificity to prime T-cell responses, and antibody-mediated effector functions.

RESULTS

As proof of concept, PeptiCab was used in murine models of melanoma and colon cancer, resulting in tumor growth control and generation of systemic T-cell-mediated antitumor responses. In specific, PeptiCab was able to generate antitumor T effector memory cells able to secrete various inflammatory cytokines. Moreover, PeptiCab was able to polarize neutrophils to attain an antigen-presenting phenotype by upregulating MHC-II, CD80 and CD86 resulting in an enhanced T-cell expansion.

CONCLUSION

Our data suggest that exploiting innate immunity activates T-cell antitumor responses, enhancing the efficiency of a vaccine platform based on oncolytic adenovirus coated with MHC-I-restricted tumor peptides.

Cancer organoids: A platform in basic and translational research

An accumulation of previous work has established organoids as good preclinical models of human tumors, facilitating translation from basic research to clinical practice. They are changing the paradigm of preclinical cancer research because they can recapitulate the heterogeneity and pathophysiology of human cancers and more closely approximate the complex tissue environment and structure found in clinical tumors than in vitro cell lines and animal models. However, the potential applications of cancer organoids remain to be comprehensively summarized. In the review, we firstly describe what is currently known about cancer organoid culture and then discuss in depth the basic mechanisms, including tumorigenesis and tumor metastasis, and describe recent advances in patient-derived tumor organoids (PDOs) for drug screening and immunological studies. Finally, the present challenges faced by organoid technology in clinical practice and its prospects are discussed. This review highlights that organoids may offer a novel therapeutic strategy for cancer research.

Comprehensive assessment of TECENTRIQ® and OPDIVO®: analyzing immunotherapy indications withdrawn in triple-negative breast cancer and hepatocellular carcinoma

Atezolizumab (TECENTRIQ®) and nivolumab (OPDIVO®) are both immunotherapeutic indications targeting programmed cell death 1 ligand 1 (PD-L1) and programmed cell death 1 (PD-1), respectively. These inhibitors hold promise as therapies for triple-negative breast cancer (TNBC) and hepatocellular carcinoma (HCC) and have demonstrated encouraging results in reducing the progression and spread of tumors. However, due to their adverse effects and low response rates, the US Food and Drug Administration (FDA) has withdrawn the approval of atezolizumab in TNBC and nivolumab in HCC treatment. The withdrawals of atezolizumab and nivolumab have raised concerns regarding their effectiveness and the ability to predict treatment responses. Therefore, the current study aims to investigate the immunotherapy withdrawal of PD-1/PD-L1 inhibitors, specifically atezolizumab for TNBC and nivolumab for HCC. This study will examine both the structural and clinical aspects. This review provides detailed insights into the structure of the PD-1 receptor and its ligands, the interactions between PD-1 and PD-L1, and their interactions with the withdrawn antibodies (atezolizumab and nivolumab) as well as PD-1 and PD-L1 modifications. In addition, this review further assesses these antibodies in the context of TNBC and HCC. It seeks to elucidate the factors that contribute to diverse responses to PD-1/PD-L1 therapy in different types of cancer and propose approaches for predicting responses, mitigating the potential risks linked to therapy withdrawals, and optimizing patient outcomes. By better understanding the mechanisms underlying responses to PD-1/PD-L1 therapy and developing strategies to predict these responses, it is possible to create more efficient treatments for TNBC and HCC.

Organoid co-culture models of the tumor microenvironment promote precision medicine

In recent years, the three-dimensional (3D) culture system has emerged as a promising preclinical model for tumor research owing to its ability to replicate the tissue structure and molecular characteristics of solid tumors in vivo. This system offers several advantages, including high throughput, efficiency, and retention of tumor heterogeneity. Traditional Matrigel-submerged organoid cultures primarily support the long-term proliferation of epithelial cells. One solution for the exploration of the tumor microenvironment is a reconstitution approach involving the introduction of exogenous cell types, either in dual, triple or even multiple combinations. Another solution is a holistic approach including patient-derived tumor fragments, air-liquid interface, suspension 3D culture, and microfluidic tumor-on-chip models. Organoid co-culture models have also gained popularity for studying the tumor microenvironment, evaluating tumor immunotherapy, identifying predictive biomarkers, screening for effective drugs, and modeling infections. By leveraging these 3D culture systems, it is hoped to advance the clinical application of therapeutic approaches and improve patient outcomes.

Oncolytic virotherapy in cancer treatment: challenges and optimization prospects

Oncolytic viruses (OVs) are emerging cancer therapeutics that offer a multifaceted therapeutic platform for the benefits of replicating and lysing tumor cells, being engineered to express transgenes, modulating the tumor microenvironment (TME), and having a tolerable safety profile that does not overlap with other cancer therapeutics. The mechanism of OVs combined with other antitumor agents is based on immune-mediated attack resistance and might benefit patients who fail to achieve durable responses after immune checkpoint inhibitor (ICI) treatment. In this Review, we summarize data on the OV mechanism and limitations of monotherapy, which are currently in the process of combination partner development, especially with ICIs. We discuss some of the hurdles that have limited the preclinical and clinical development of OVs. We also describe the available data and provide guidance for optimizing OVs in clinical practice, as well as a summary of approved and promising novel OVs with clinical indications.

Personalizing Oncolytic Virotherapy

The use of oncolytic viruses has become an attractive tool in the clinics for the treatment of various tumor types. Such viruses are genetically modified to conditionally replicate in malignant cells while unharming healthy cells. This platform offers a highly specific tumor killing with exceptional safety profiles. However, the use of oncolytic viruses as sole oncolytic platforms has not achieved full tumor clearance in murine models and in the clinics. In fact, the formation of anti-tumor immune responses is attributed to the effectiveness of oncolytic viruses. In this review, we will discuss the various strategies that scientists have employed to enhance the anti-tumor immune responses driven by oncolytic viruses. Moreover, focus will be drawn into personalizing such anti-tumor responses by the addition of tumor-associated peptides.

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.

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.

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.

Controlled release of enhanced cross-hybrid IgGA Fc PD-L1 inhibitors using oncolytic adenoviruses

Immune checkpoint inhibitors have clinical success in prolonging the life of many cancer patients. However, only a minority of patients benefit from such therapy, calling for further improvements. Currently, most PD-L1 checkpoint inhibitors in the clinic do not elicit Fc effector mechanisms that would substantially increase their efficacy. To gain potency and circumvent off-target effects, we previously designed an oncolytic adenovirus (Ad-Cab) expressing an Fc fusion peptide against PD-L1 on a cross-hybrid immunoglobulin GA (IgGA) Fc. Ad-Cab elicited antibody effector mechanisms of IgG1 and IgA, which led to higher tumor killing compared with each isotype alone and with clinically approved PD-L1 checkpoint inhibitors. In this study, we further improved the therapy to increase the IgG1 Fc effector mechanisms of the IgGA Fc fusion peptide (Ad-Cab FT) by adding four somatic mutations that increase natural killer (NK) cell activation. Ad-Cab FT was shown to work better at lower concentrations compared with Ad-Cab in vitro and in vivo and to have better tumor- and myeloid-derived suppressor cell killing, likely because of higher NK cell activation. Additionally, the biodistribution of the Fc fusion peptide demonstrated targeted release in the tumor microenvironment with minimal or no leakage to the peripheral blood and organs in mice. These data demonstrate effective and safe use of Ad-Cab FT, bidding for further clinical investigation.

Oncolytic adenovirus-mediated dual knockdown of survivin and OCT4 improves therapeutic efficacy in esophageal cancer

Background

Survivin and octamer-binding transcription factor 4 (OCT4) are reportedly up-regulated in esophageal cancer (EC) and have been correlated with high tumor proliferative activity and poor prognosis. Oncolytic viruses encoding specific transgenes have been considered as therapeutic methods to increase therapeutic efficacy in a variety of solid tumors.

Methods

In this study, an oncolytic adenovirus carrying short hairpin RNA (shRNA) of survivin (shSRVN) and OCT4 (shOCT4) was constructed to achieve dual knockdown of survivin and OCT4 and to explore the potential effect of the oncolytic adenovirus in EC.

Results

The oncolytic adenovirus replicated abundantly in human EC cells, with the replication multiplying by up to 192,085 and 620,055 times in esophageal carcinoma (Eca)-109 cells transfected with purified and completed recombinant adenoviruses called AdSProE1a-dual shRNA (shSRVN + shOCT4) and TE1 cells transfected with AdSProE1a-survivin shRNA (shSRVN) 96 hours after infection, respectively. The shRNAs targeting survivin and OCT4 significantly downregulated the expression levels of survivin and OCT4 in cells, thereby inhibiting the proliferative activity of cancer cells. Furthermore, E-cadherin and vimentin, which are both considered epithelial mesenchymal transition (EMT) markers, were found to be upregulated and downregulated, respectively, in cancer cells after exposure to the viral infection. The interference of survivin and OCT4 also contributed to cell cycle arrest and apoptosis, the half maximal inhibitory concentrations (IC50s) of oncolytic adenovirus loaded with AdSProE1a-shSRVN + shOCT4 in the Eca109 cells and the TE1 cells were 0.7271 and 0.1032 pfu/mL, respectively. Xenograft experiments in vivo showed that oncolytic adenovirus-mediated dual knockdown of survivin and OCT4 effectively inhibited the growth of xenografts and induced cancer cell apoptosis. We concluded that therapies targeting survivin and OCT4 have great potential for improving the therapeutic efficacy in EC.

Conclusions

The dual target design strategy ensured the efficacy and safety of the treatment system and provided a novel and effective adjuvant target therapy for EC.

The impact of oncolytic adenoviral therapy on the therapeutic efficacy of PD-1/PD-L1 blockade

Immunotherapy has revolutionized treatment of cancer during the last decades. Oncolytic virotherapy has also emerged as a strategy to fight against cancer cells both via lysis of malignant cells and activating immune responses. Accepted as a logical strategy, combination of monoclonal antibodies particularly against the programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) is introduced to improve clinical responses to immune checkpoint inhibitors (ICIs). Accordingly, Talimogene laherparepvec (T-VEC) has received approval for clinical use, while a number of oncolytic Adenoviruses (Ads) are being investigated in clinical trials of malignancies. Combination of oncolytic Ads with PD-1/PD-L1 inhibitors have shown potentials in promoting responses to ICIs, changing the tumor microenvironment, inducing long-term protection against tumor, and promoting survival among mice models of malignancies. Regarding the increasing importance of oncolytic Ads in combination therapy of cancers, in this review we decide to outline recent studies in this field.

Patient-derived xenografts or organoids in the discovery of traditional and self-assembled drug for tumor immunotherapy

In addition to the rapid development of immune checkpoint inhibitors, there has also been a surge in the development of self-assembly immunotherapy drugs. Based on the immune target, traditional tumor immunotherapy drugs are classified into five categories, namely immune checkpoint inhibitors, direct immune modulators, adoptive cell therapy, oncolytic viruses, and cancer vaccines. Additionally, the emergence of self-assembled drugs with improved precision and environmental sensitivity offers a promising innovation approach to tumor immunotherapy. Despite rapid advances in tumor immunotherapy drug development, all candidate drugs require preclinical evaluation for safety and efficacy, and conventional evaluations are primarily conducted using two-dimensional cell lines and animal models, an approach that may be unsuitable for immunotherapy drugs. The patient-derived xenograft and organoids models, however, maintain the heterogeneity and immunity of the pathological tumor heterogeneity.

Multi-functional extracellular vesicles: Potentials in cancer immunotherapy

Cancer immunotherapy (CIT) has revolutionized cancer treatment. However, the application of CIT is limited by low response rates and significant individual differences owing to a deficit in 1) immune recognition and 2) immune effector function. Extracellular vesicles (EVs) are cell-derived lipid bilayer-enclosed vesicles that mediate intercellular communication. The specific structure and content of EVs allows for multi-functional modulation of tumor immunity. Given their high biocompatibility, homologous targeting, and permeability across biological barriers, EVs have been evaluated as ideal carriers for promoting the efficacy and specificity of CIT. Herein, we first discuss the role of EVs in regulating tumor immunity and focus on the advantages of using EVs as a therapeutic tool for cancer treatment from a clinical perspective. Further, we outline the current progress in the development of biohybrid EVs for CIT and multi-functional EV-based strategies for overcoming the deficits in tumor immunity. Finally, we discuss the challenges associated with EV-based CIT and future perspectives in the context of ongoing clinical trials involving EV-based therapies, thus offering valuable insights into the future of multi-functional EVs in CIT.

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

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

Oncolytic viruses combined with immune checkpoint therapy for colorectal cancer is a promising treatment option

Immunotherapy is one of the promising strategies in the treatment of oncology. Immune checkpoint inhibitors, as a type of immunotherapy, have no significant efficacy in the clinical treatment of patients with pMMR/MSS/MSI-L mCRC alone. Therefore, there is an urgent need to find combination therapies that can improve the response rate of immune checkpoint inhibitors. Oncolytic viruses are a new class of cancer drugs that, in addition to directly lysing tumor cells, can facilitate the action of immune checkpoint inhibitors by modulating the tumor microenvironment and transforming “cold” tumors into “hot” ones. The combination of oncolytic viruses and immune checkpoint inhibitors is currently being used in several primary and clinical studies to treat tumors with exciting results. The combination of genetically modified “armed” OV with ICIs is expected to be one of the treatment options for pMMR/MSS/MSI-L mCRC. In this paper, we will analyze the current status of oncolytic viruses and ICIs available for the treatment of CRC. The feasibility of OV in combination with ICI for CRC will be discussed in terms of the mechanism of action of OV in treating tumors.

Oncolytic viruses: challenges and considerations in an evolving clinical landscape

Despite advances in treatment, cancer remains a leading cause of death worldwide. Although treatment strategies are continually progressing, cancers have evolved many mechanisms for evading therapies and the host immune system. Oncolytic viruses (OVs) could provide a much-needed option for cancers that are resistant to existing treatments. OVs can be engineered to specifically target and kill cancer cells, while simultaneously triggering an immune response at the site of infection. This review will focus on the challenges of developing a successful OV and translation to clinical practice, discussing the innovative strategies that are being used to optimize the potential of OVs. Here, we will also explore the current clinical landscape and the prospects of OVs in early clinical development.

The Influence of Oncogenic Viruses in Renal Carcinogenesis: Pros and Cons

Viral infections are major contributors to the global cancer burden. Recent advances have revealed that known oncogenic viruses promote carcinogenesis through shared host cell targets and pathways. The aim of this review is to point out the connection between several oncogenic viruses from the Polyomaviridae, Herpesviridae and Flaviviridae families and renal carcinogenesis, highlighting their involvement in the carcinogenic mechanism. We performed a systematic search of the PubMed and EMBASE databases, which was carried out for all the published studies on RCC in the last 10 years, using the following search algorithm: renal cell carcinoma (RCC) and urothelial carcinoma, and oncogenic viruses (BKPyV, EBV, HCV, HPV and Kaposi Sarcoma Virus), RCC and biomarkers, immunohistochemistry (IHC). Our analysis included studies that were published in English from the 1st of January 2012 to the 1st of May 2022 and that described and analyzed the assays used for the detection of oncogenic viruses in RCC and urothelial carcinoma. The virus most frequently associated with RCC was BKPyV. This review of the literature will help to understand the pathogenic mechanism of the main type of renal malignancy and whether the viral etiology can be confirmed, at a minimum, as a co-factor. In consequence, these data can contribute to the development of new therapeutic strategies. A virus-induced tumor could be efficiently prevented by vaccination or treatment with oncolytic viral therapy and/or by targeted therapy.

Tumor organoids: applications in cancer modeling and potentials in precision medicine

Cancer is a top-ranked life-threatening disease with intratumor heterogeneity. Tumor heterogeneity is associated with metastasis, relapse, and therapy resistance. These factors contribute to treatment failure and an unfavorable prognosis. Personalized tumor models faithfully capturing the tumor heterogeneity of individual patients are urgently needed for precision medicine. Advances in stem cell culture have given rise to powerful organoid technology for the generation of in vitro three-dimensional tissues that have been shown to more accurately recapitulate the structures, specific functions, molecular characteristics, genomic alterations, expression profiles, and tumor microenvironment of primary tumors. Tumoroids in vitro serve as an important component of the pipeline for the discovery of potential therapeutic targets and the identification of novel compounds. In this review, we will summarize recent advances in tumoroid cultures as an excellent tool for accurate cancer modeling. Additionally, vascularization and immune microenvironment modeling based on organoid technology will also be described. Furthermore, we will summarize the great potential of tumor organoids in predicting the therapeutic response, investigating resistance-related mechanisms, optimizing treatment strategies, and exploring potential therapies. In addition, the bottlenecks and challenges of current tumoroids will also be discussed in this review.

Patient-Derived Tumor Organoids: New Progress and Opportunities to Facilitate Precision Cancer Immunotherapy

Cancer immunotherapy has revolutionized the field of cancer treatment in recent years. However, not all patients receiving cancer immunotherapy exhibit durable responses, and reliable, high-throughput testing platforms are urgently needed to guide personalized cancer immunotherapy. The ability of patient-derived tumor organoids to recapitulate pivotal features of original cancer tissues makes them useful as a preclinical model for cancer research and precision medicine. Nevertheless, many challenges exist in the translation of tumor organoid research to clinical decision making. Herein we discuss the applications of patient-derived tumor organoid models and the advances and potential of using complex immune-organoid systems as testing platforms to facilitate precision cancer immunotherapy. In addition, we highlight intriguing applications of tumor organoids with novel multi-omics in preclinical cancer research, highlighting genetic editing, proteomics, and liquid biopsy.

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

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

Current development in adenoviral vectors for cancer immunotherapy

Adenoviruses are well characterized and thus easily modified to generate oncolytic vectors that directly lyse tumor cells and can be "armed" with transgenes to promote lysis, antigen presentation, and immunostimulation. Oncolytic adenoviruses (OAds) are safe, versatile, and potent immunostimulants in patients. Since transgene expression is restricted to the tumor, adenoviral transgenes overcome the toxicities and short half-life of systemically administered cytokines, immune checkpoint blockade molecules, and bispecific T cell engagers. While OAds expressing immunostimulatory molecules ("armed" OAds) have demonstrated anti-tumor potential in preclinical solid tumor models, the efficacy has not translated into significant clinical outcomes as a monotherapy. However, OAds synergize with established standards of care and novel immunotherapeutic agents, providing a multifaceted means to address complexities associated with solid tumors. Critically, armed OAds revitalize endogenous and adoptively transferred immune cells while simultaneously enhancing their anti-tumor function. To properly evaluate these novel vectors and reduce the gap in the cycle between bench-to-bedside and back, improving model systems must be a priority. The future of OAds will involve a multidimensional approach that provides immunostimulatory molecules, immune checkpoint blockade, and/or immune engagers in concert with endogenous and exogenous immune cells to initiate durable and comprehensive anti-tumor responses.