Oncolytic Adenoviruses: Strategies for Improved Targeting and Specificity

Neoadjuvant immunotherapy and oncolytic virotherapy in HPV positive and HPV negative skin cancer: A comprehensive review

Skin cancer is the most common new cancer among Caucasians. This cancer has different types, of which non-melanoma skin cancer is the most common type. Various factors affect this disease, one of which is viral infections, including HPV. This virus plays an important role in skin cancer, especially cSCCs. There are various options for the treatment of skin cancer, and today special attention has been paid to treatments based on therapeutic goals, immunotherapy and combination therapy. In this study, we have investigated treatments based on immunotherapy and virotherapy and the effect of HPV virus on the effectiveness of these treatments in skin cancer. Treatments based on virotherapy are performed for a long time in combination with other common treatments such as radiotherapy and chemotherapy in order to have a greater effect and lower its side effects, which include: shortness of breath, tachycardia, lowering blood pressure in the patient. Also, the most important axis of immunotherapy is to focus on PD1-PDL1, despite abundant evidence on the importance of immunotherapy, many studies investigate the use of immunotherapy inhibitors in the adjuvant and neoadjuvant setting in various cancers. Also, previous findings show conflicting evidence of the effect of HPV status on the response to immunotherapy.

Redirect Tropism of Fowl Adenovirus 4 Vector by Modifying Fiber2 with Variable Domain of Heavy-Chain Antibody

The variable domain of a heavy-chain antibody (VHH) has the potential to be used to redirect the cell tropism of adenoviral vectors. Here, we attempted to establish platforms to simplify the screening of VHHs for their specific targeting function when being incorporated into the fiber of adenovirus. Both fowl adenovirus 4 (FAdV-4) and simian adenovirus 1 (SAdV-1) have two types of fiber, one of which is dispensable for virus propagation and is a proper site for VHH display. An intermediate plasmid, pMD-FAV4Fs, was constructed as the start plasmid for FAdV-4 fiber2 modification. Foldon from phage T4 fibritin, a trigger for trimerization, was employed to bridge the tail/shaft domain of fiber2 and VHHs against human CD16A, a key membrane marker of natural killer (NK) cells. Through one step of restriction-assembly, the modified fiber2 was transferred to the adenoviral plasmid, which was linearized and transfected to packaging cells. Five FAdV-4 viruses carrying the GFP gene were finally rescued and amplified, with three VHHs being displayed. One recombinant virus, FAdV4FC21-EG, could hardly transduce human 293 or Jurkat cells. In contrast, when it was used at a multiplicity of infection of 1000 viral particles per cell, the transduction efficiency reached 51% or 34% for 293 or Jurkat cells expressing exogenous CD16A. Such a strategy of fiber modification was transplanted to the SAdV-1 vector to construct SAdV1FC28H-EG, which moderately transduced primary human NK cells while the parental virus transduced none. Collectively, we reformed the strategy of integrating VHH to fiber and established novel platforms for screening VHHs to construct adenoviral vectors with a specific tropism.

Role of homologous recombination/recombineering on human adenovirus genome engineering: Not the only but the most competent solution

Adenoviruses typically cause mild illnesses, but severe diseases may occur primarily in immunodeficient individuals, particularly children. Recently, adenoviruses have garnered significant interest as a versatile tool in gene therapy, tumor treatment, and vaccine vector development. Over the past two decades, the advent of recombineering, a method based on homologous recombination, has notably enhanced the utility of adenoviral vectors in therapeutic applications. This review summarizes recent advancements in the use of human adenoviral vectors in medicine and discusses the pivotal role of recombineering in the development of these vectors. Additionally, it highlights the current achievements and potential future impact of therapeutic adenoviral vectors.

Joining Forces: The Combined Application of Therapeutic Viruses and Nanomaterials in Cancer Therapy

Cancer, on a global scale, presents a monumental challenge to our healthcare systems, posing a significant threat to human health. Despite the considerable progress we have made in the diagnosis and treatment of cancer, realizing precision cancer therapy, reducing side effects, and enhancing efficacy remain daunting tasks. Fortunately, the emergence of therapeutic viruses and nanomaterials provides new possibilities for tackling these issues. Therapeutic viruses possess the ability to accurately locate and attack tumor cells, while nanomaterials serve as efficient drug carriers, delivering medication precisely to tumor tissues. The synergy of these two elements has led to a novel approach to cancer treatment-the combination of therapeutic viruses and nanomaterials. This advantageous combination has overcome the limitations associated with the side effects of oncolytic viruses and the insufficient tumoricidal capacity of nanomedicines, enabling the oncolytic viruses to more effectively breach the tumor's immune barrier. It focuses on the lesion site and even allows for real-time monitoring of the distribution of therapeutic viruses and drug release, achieving a synergistic effect. This article comprehensively explores the application of therapeutic viruses and nanomaterials in tumor treatment, dissecting their working mechanisms, and integrating the latest scientific advancements to predict future development trends. This approach, which combines viral therapy with the application of nanomaterials, represents an innovative and more effective treatment strategy, offering new perspectives in the field of tumor therapy.

Technological advances in the use of viral and non-viral vectors for delivering genetic and non-genetic cargos for cancer therapy

The burden of cancer is increasing globally. Several challenges facing its mainstream treatment approaches have formed the basis for the development of targeted delivery systems to carry and distribute anti-cancer payloads to their defined targets. This site-specific delivery of drug molecules and gene payloads to selectively target druggable biomarkers aimed at inducing cell death while sparing normal cells is the principal goal for cancer therapy. An important advantage of a delivery vector either viral or non-viral is the cumulative ability to penetrate the haphazardly arranged and immunosuppressive tumour microenvironment of solid tumours and or withstand antibody-mediated immune response. Biotechnological approaches incorporating rational protein engineering for the development of targeted delivery systems which may serve as vehicles for packaging and distribution of anti-cancer agents to selectively target and kill cancer cells are highly desired. Over the years, these chemically and genetically modified delivery systems have aimed at distribution and selective accumulation of drug molecules at receptor sites resulting in constant maintenance of high drug bioavailability for effective anti-tumour activity. In this review, we highlighted the state-of-the art viral and non-viral drug and gene delivery systems and those under developments focusing on cancer therapy.

In Vitro and In Vivo Efficacy of a Stroma-Targeted, Tumor Microenvironment Responsive Oncolytic Adenovirus in Different Preclinical Models of Cancer

More than one million women are diagnosed annually worldwide with a gynecological cancer. Most gynecological cancers are diagnosed at a late stage, either because a lack of symptoms, such as in ovarian cancer or limited accessibility to primary prevention in low-resource countries, such as in cervical cancer. Here, we extend the studies of AR2011, a stroma-targeted and tumor microenvironment responsive oncolytic adenovirus (OAdV), whose replication is driven by a triple hybrid promoter. We show that AR2011 was able to replicate and lyse in vitro fresh explants obtained from human ovarian cancer, uterine cancer, and cervical cancer. AR2011 was also able to strongly inhibit the in vitro growth of ovarian malignant cells obtained from human ascites fluid. The virus could synergize in vitro with cisplatin even on ascites-derived cells obtained from patients heavily pretreated with neoadjuvant chemotherapy. AR2011(h404), a dual transcriptionally targeted derived virus armed with hCD40L and h41BBL under the regulation of the hTERT promoter, showed a strong efficacy in vivo both on subcutaneous and intraperitoneally established human ovarian cancer in nude mice. Preliminary studies in an immunocompetent murine tumor model showed that AR2011(m404) expressing the murine cytokines was able to induce an abscopal effect. The present studies suggest that AR2011(h404) is a likely candidate as a novel medicine for intraperitoneal disseminated ovarian cancer.

A Structure-Guided Genetic Modification Strategy: Developing Seneca Valley Virus Therapy against Nonsensitive Nonsmall Cell Lung Carcinoma

Numerous studies have illustrated that the Seneca Valley virus (SVV) shows sufficient oncolytic efficacy targeting small cell lung cancer (SCLC). However, the therapeutics of nonsmall cell lung carcinoma (NSCLC, accounts for 85% of lung cancer cases) using oncolytic virus have been resisting due to the filtration of neutralizing antibody and limited reproduction capacity. Here, we employed structural biology and reverse genetics to optimize novel oncolytic SVV mutants (viral receptor-associated mutant SVV-S177A and viral antigenic peptide-related variant SVV-S177A/P60S) with increased infectivity and lower immunogenicity. The results of the NSCLC-bearing athymic mouse model demonstrated that wild-type (wt) SVV-HB extended the median overall survival (mOS) from 11 days in the PBS group to 19 days. Notably, the newly discovered mutations significantly (P < 0.001) prolonged the mOS from 11 days in the control cohort to 23 days in the SVV-S177A cohort and the SVV-S177A/P60S cohort. Taken together, we present a structure-guided genetic modification strategy for oncolytic SVV optimization and provide a candidate for developing oncolytic viral therapy against nonsensitive NSCLC. IMPORTANCE Nonsmall cell lung cancer (NSCLC) accounts for approximately 85% of lung cancer cases (more than 1.85 million cases with 1.48 million deaths in 2020). In the present study, two novel oncolytic SVV mutants modified based on structural biology and reverse genetics (viral receptor-associated mutant SVV-S177A and viral antigenic peptide-related mutant SVV-S177A/P60S) with increased infectivity or lower immunogenicity significantly (P < 0.001) prolonged the mOS from 11 days in the control cohort to 23 days in the SVV-S177A cohort and the SVV-S177A/P60S cohort in the NSCLC-bearing athymic mouse model, which may provide the direction for modifying SVV to improve the effect of oncolysis.

Gene-based delivery of immune-activating cytokines for cancer treatment

Tumors evolve together with the tumor microenvironment (TME) and reshape it towards immunosuppression. Immunostimulating cytokines can be used to revert this state leading to effective antitumor immune responses, but their exploitation as anticancer drugs has been hampered by severe toxicity associated with systemic administration. Local, TME-targeted delivery of immune activating cytokines can deploy their antitumoral function more effectively than systemic administration while, at the same time, avoiding exposure of healthy organs and limiting toxicity. Here, we review different gene and cell therapy platforms developed for tumor-directed cytokine delivery highlighting their potential for clinical translation.

Fiber manipulation and post-assembly nanobody conjugation for adenoviral vector retargeting through SpyTag-SpyCatcher protein ligation

For adenoviruses (Ads) to be optimally effective in cancer theranostics, they need to be retargeted toward target cells and lose their natural tropism. Typically, this is accomplished by either engineering fiber proteins and/or employing bispecific adapters, capable of bonding Ad fibers and tumor antigen receptors. This study aimed to present a simple and versatile method for generating Ad-based bionanoparticles specific to target cells, using the SpyTag-SpyCatcher system. The SpyTag peptide was inserted into the HI loop of fiber-knob protein, which could act as a covalent anchoring site for a targeting moiety fused to a truncated SpyCatcher (SpyCatcherΔ) pair. After confirming the presence and functionality of SpyTag on the Ad type-5 (Ad5) fiber knob, an adapter molecule, comprising of SpyCatcherΔ fused to an anti-vascular endothelial growth factor receptor 2 (VEGFR2) nanobody, was recombinantly expressed in Escherichia coli and purified before conjugation to fiber-modified Ad5 (fmAd5). After evaluating fmAd5 detargeting from its primary coxsackie and adenovirus receptor (CAR), the nanobody-decorated fmAd5 could be efficiently retargeted to VEGFR2-expressing 293/KDR and human umbilical vein endothelial (HUVEC) cell lines. In conclusion, a plug-and-play platform was described in this study for detargeting and retargeting Ad5 through the SpyTag-SpyCatcher system, which could be potentially applied to generate tailored bionanoparticles for a broad range of specific targets; therefore, it can be introduced as a promising approach in cancer nanotheranostics.

M11: A Tropism-modified Oncolytic Adenovirus Arming with Tumor-homing Peptide for Advanced Ovarian Cancer Therapies

Oncolytic adenoviruses (OAds) have shown great promise in cancer therapy, but their efficacy has been greatly limited by poor tumor selectivity and highly off-target liver sequestration. Herein, we generate a novel "stealth' and tumor-targeting oncolytic adenovirus vector M0-TMTP1 through inserting TMTP1 (NVVRQ), a tumor homing peptide specifically targeting metastasis, into the hypervariable region 5 (HVR5) of hexon. M0-TMTP1 exhibits increased transduction of tumor cells in vitro. In vivo biodistribution of M0-TMTP1 in an intraperitoneal disseminated ovarian cancer model showed significantly reduced virus load in major organs but apparent aggregation in tumors. The tumor-to-liver ratio of M0-TMTP1 was nearly 5000-fold higher than control adenovirus M0. Further, we armed M0-TMTP1 with trunked BID (tBID), a mitochondrial apoptosis protein, to obtain M11. Combining M11 with cisplatin (DDP) could induce an intensive antitumor effect in vitro and in vivo. Moreover, this combination therapy showed higher biosafety. Taken together, our results suggest that M11 represents a tumor-targeting, efficacious, and relatively nontoxic viro-therapeutic agent, and these findings might offer renewed hope for tumor management.

Apoptin induces pyroptosis of colorectal cancer cells via the GSDME-dependent pathway

Apoptin is a small molecular weight protein encoded by the VP3 gene of chicken anemia virus (CAV). It can induce apoptosis of tumor cells and play anti-tumorigenic functions. In this study, we identified a time-dependent inhibitory role of apoptin on the viability of HCT116 cells. We also demonstrated that apoptin induces pyroptosis through cleaved caspase 3, and with a concomitant cleavage of gasdermin E (GSDME) rather than GSDMD. GSDME knockdown switched the apoptin-induced cell death from pyroptosis to apoptosis in vitro. Furthermore, we demonstrated that the effect of apoptin on GSDME-dependent pyroptosis could be mitigated by caspase-3 and caspase-9 siRNA knockdown. Additionally, apoptin enhanced the intracellular reactive oxygen species (ROS), causing aggregation of the mitochondrial membrane protein Tom20. Moreover, bax and cytochrome c were released to the activating caspase-9, eventually triggering pyroptosis. Therefore, GSDME mediates the apoptin-induced pyroptosis through the mitochondrial apoptotic pathway. Finally, using nude mice xenografted with HCT116 cells, we found that apoptin induces pyroptosis and significantly inhibits tumor growth. Based on this mechanism, apoptin may provide a new strategy for colorectal cancer therapy.

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.

Self-Assembly System Based on Cyclodextrin for Targeted Delivery of Cannabidiol

Cannabidiol (CBD) is one specific kind of the cannabinoid in Cannabis sativa L with a wide range of pharmacological activities. However, the poor water solubility and specificity of CBD limits its application in pharmaceutical field. For solving these problems, in this work, we successfully prepared a targeted carrier by grafting biotin (BIO) onto ethylenediamine-β-Cyclodextrin (EN-CD) in a single step to generate a functionalized supramolecule, named BIO-CD. Subsequently, an amantadine-conjugated cannabinoids (AD-CBD) was prepared and self-assembled with the BIO-CD. A series of methods were used to characterize the inclusion behavior and physicochemical properties of AD-CBD and BIO-CD. The results showed that AD-CBD entered the cavity of BIO-CD and formed a 1:1 host-guest inclusion complex. MTT assay and confocal laser scanning microscopy (CLSM) revealed that the targeting effect and anticancer activity of AD-CBD/BIO-CD inclusion complex against three human cancer cell lines were higher than BIO-CD, AD-CBD and free CBD. Moreover, the inclusion complex could release drugs under weakly acidic conditions. These results demonstrated that AD-CBD/BIO-CD inclusion complex possess excellent targeted and anticancer activity, which is hopeful to be applied in clinic as a new therapeutic approach.

Brain Cancer Drug Discovery: Clinical Trials, Drug Classes, Targets, and Combinatorial Therapies

Brain cancer is a formidable challenge for drug development, and drugs derived from many cutting-edge technologies are being tested in clinical trials. We manually characterized 981 clinical trials on brain tumors that were registered in ClinicalTrials.gov from 2010 to 2020. We identified 582 unique therapeutic entities targeting 581 unique drug targets and 557 unique treatment combinations involving drugs. We performed the classification of both the drugs and drug targets based on pharmacological and structural classifications. Our analysis demonstrates a large diversity of agents and targets. Currently, we identified 32 different pharmacological directions for therapies that are based on 42 structural classes of agents. Our analysis shows that kinase inhibitors, chemotherapeutic agents, and cancer vaccines are the three most common classes of agents identified in trials. Agents in clinical trials demonstrated uneven distribution in combination approaches; chemotherapy agents, proteasome inhibitors, and immune modulators frequently appeared in combinations, whereas kinase inhibitors, modified immune effector cells did not as was shown by combination networks and descriptive statistics. This analysis provides an extensive overview of the drug discovery field in brain cancer, shifts that have been happening in recent years, and challenges that are likely to come. SIGNIFICANCE STATEMENT: This review provides comprehensive quantitative analysis and discussion of the brain cancer drug discovery field, including classification of drug, targets, and therapies.

Adoptive Immunotherapy beyond CAR T-Cells

Adoptive cell immunotherapy (ACT) is a vibrant field of cancer treatment that began progressive development in the 1980s. One of the most prominent and promising examples is chimeric antigen receptor (CAR) T-cell immunotherapy for the treatment of B-cell hematologic malignancies. Despite success in the treatment of B-cell lymphomas and leukemia, CAR T-cell therapy remains mostly ineffective for solid tumors. This is due to several reasons, such as the heterogeneity of the cellular composition in solid tumors, the need for directed migration and penetration of CAR T-cells against the pressure gradient in the tumor stroma, and the immunosuppressive microenvironment. To substantially improve the clinical efficacy of ACT against solid tumors, researchers might need to look closer into recent developments in the other branches of adoptive immunotherapy, both traditional and innovative. In this review, we describe the variety of adoptive cell therapies beyond CAR T-cell technology, i.e., exploitation of alternative cell sources with a high therapeutic potential against solid tumors (e.g., CAR M-cells) or aiming to be universal allogeneic (e.g., CAR NK-cells, γδ T-cells), tumor-infiltrating lymphocytes (TILs), and transgenic T-cell receptor (TCR) T-cell immunotherapies. In addition, we discuss the strategies for selection and validation of neoantigens to achieve efficiency and safety. We provide an overview of non-conventional TCRs and CARs, and address the problem of mispairing between the cognate and transgenic TCRs. Finally, we summarize existing and emerging approaches for manufacturing of the therapeutic cell products in traditional, semi-automated and fully automated Point-of-Care (PoC) systems.

Oncolytic Virotherapy in Solid Tumors: The Challenges and Achievements

Oncolytic virotherapy (OVT) is a promising approach in cancer immunotherapy. Oncolytic viruses (OVs) could be applied in cancer immunotherapy without in-depth knowledge of tumor antigens. The capability of genetic modification makes OVs exciting therapeutic tools with a high potential for manipulation. Improving efficacy, employing immunostimulatory elements, changing the immunosuppressive tumor microenvironment (TME) to inflammatory TME, optimizing their delivery system, and increasing the safety are the main areas of OVs manipulations. Recently, the reciprocal interaction of OVs and TME has become a hot topic for investigators to enhance the efficacy of OVT with less off-target adverse events. Current investigations suggest that the main application of OVT is to provoke the antitumor immune response in the TME, which synergize the effects of other immunotherapies such as immune-checkpoint blockers and adoptive cell therapy. In this review, we focused on the effects of OVs on the TME and antitumor immune responses. Furthermore, OVT challenges, including its moderate efficiency, safety concerns, and delivery strategies, along with recent achievements to overcome challenges, are thoroughly discussed.

The Role of Adenovirus in Cancer Therapy

This series of 13 articles (7 original articles, 6 reviews) is presented by international leaders in adenovirus-based cancer therapy [...].

Efficient Delivery and Replication of Oncolytic Virus for Successful Treatment of Head and Neck Cancer

Head and neck cancer has been treated by a combination of surgery, radiation, and chemotherapy. In recent years, the development of immune checkpoint inhibitors (ICIs) has made immunotherapy a new treatment method. Oncolytic virus (OV) therapy selectively infects tumor cells with a low-pathogenic virus, lyses tumor cells by the cytopathic effects of the virus, and induces anti-tumor immunity to destroy tumors by the action of immune cells. In OV therapy for head and neck squamous cell carcinoma (HNSCC), viruses, such as herpes simplex virus type 1 (HSV-1), vaccinia virus, adenovirus, reovirus, measles virus, and vesicular stomatitis virus (VSV), are mainly used. As the combined use of mutant HSV-1 and ICI was successful for the treatment of melanoma, studies are underway to combine OV therapy with radiation, chemotherapy, and other types of immunotherapy. In such therapy, it is important for the virus to selectively replicate in tumor cells, and to express the viral gene and the introduced foreign gene in the tumor cells. In OV therapy for HNSCC, it may be useful to combine systemic and local treatments that improve the delivery and replication of the inoculated oncolytic virus in the tumor cells.