Enhanced lysis by bispecific oncolytic measles viruses simultaneously using HER2/neu or EpCAM as target receptors

Improvement of current immunotherapies with engineered oncolytic viruses that target cancer stem cells

The heterogeneity of the solid tumor microenvironment (TME) impairs the therapeutic efficacy of standard therapies and also reduces the infiltration of antitumor immune cells, all of which lead to tumor progression and invasion. In addition, self-renewing cancer stem cells (CSCs) support tumor dormancy, drug resistance, and recurrence, all of which might pose challenges to the eradication of malignant tumor masses with current therapies. Natural forms of oncolytic viruses (OVs) or engineered OVs are known for their potential to directly target and kill tumor cells or indirectly eradicate tumor cells by involving antitumor immune responses, including enhancement of infiltrating antitumor immune cells, induction of immunogenic cell death, and reprogramming of cold TME to an immune-sensitive hot state. More importantly, OVs can target stemness factors that promote tumor progression, which subsequently enhances the efficacy of immunotherapies targeting solid tumors, particularly the CSC subpopulation. Herein, we describe the role of CSCs in tumor heterogeneity and resistance and then highlight the potential and remaining challenges of immunotherapies targeting CSCs. We then review the potential of OVs to improve tumor immunogenicity and target CSCs and finally summarize the challenges within the therapeutic application of OVs in preclinical and clinical trials.

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.

Gene Therapy for Malignant and Benign Gynaecological Disorders: A Systematic Review of an Emerging Success Story

Simple Summary

This review discusses all the major advances in gene therapy of gynaecological disorders, highlighting the novel and potentially therapeutic perspectives associated with such an approach. It specifically focuses on the gene therapy strategies against major gynaecological malignant disorders, such as ovarian, cervical, and endometrial cancer, as well as benign disorders, such as uterine leiomyomas, endometriosis, placental, and embryo implantation disorders. The above therapeutic strategies, which employ both viral and non-viral systems for mutation compensation, suicide gene therapy, oncolytic virotherapy, antiangiogenesis and immunopotentiation approaches, have yielded promising results over the last decade, setting the grounds for successful clinical trials.

Abstract

Despite the major advances in screening and therapeutic approaches, gynaecological malignancies still present as a leading cause of death among women of reproductive age. Cervical cancer, although largely preventable through vaccination and regular screening, remains the fourth most common and most lethal cancer type in women, while the available treatment schemes still pose a fertility threat. Ovarian cancer is associated with high morbidity rates, primarily due to lack of symptoms and high relapse rates following treatment, whereas endometrial cancer, although usually curable by surgery, it still represents a therapeutic problem. On the other hand, benign abnormalities, such as fibroids, endometriosis, placental, and embryo implantation disorders, although not life-threatening, significantly affect women’s life and fertility and have high socio-economic impacts. In the last decade, targeted gene therapy approaches toward both malignant and benign gynaecological abnormalities have led to promising results, setting the ground for successful clinical trials. The above therapeutic strategies employ both viral and non-viral systems for mutation compensation, suicide gene therapy, oncolytic virotherapy, antiangiogenesis and immunopotentiation. This review discusses all the major advances in gene therapy of gynaecological disorders and highlights the novel and potentially therapeutic perspectives associated with such an approach.

Prospects for Using Expression Patterns of Paramyxovirus Receptors as Biomarkers for Oncolytic Virotherapy

Simple Summary

Some non-pathogenic viruses that do not cause serious illness in humans can efficiently target and kill cancer cells and may be considered candidates for cancer treatment with virotherapy. However, many cancer cells are protected from viruses. An important goal of personalized cancer treatment is to identify viruses that can kill a certain type of cancer cells. To this end, researchers investigate expression patterns of cell entry receptors, which viruses use to bind to and enter host cells. We summarized and analyzed the receptor expression patterns of two paramyxoviruses: The non-pathogenic measles and the Sendai viruses. The receptors for these viruses are different and can be proteins or lipids with attached carbohydrates. This review discusses the prospects for using these paramyxovirus receptors as biomarkers for successful personalized virotherapy for certain types of cancer.

Abstract

The effectiveness of oncolytic virotherapy in cancer treatment depends on several factors, including successful virus delivery to the tumor, ability of the virus to enter the target malignant cell, virus replication, and the release of progeny virions from infected cells. The multi-stage process is influenced by the efficiency with which the virus enters host cells via specific receptors. This review describes natural and artificial receptors for two oncolytic paramyxoviruses, nonpathogenic measles, and Sendai viruses. Cell entry receptors are proteins for measles virus (MV) and sialylated glycans (sialylated glycoproteins or glycolipids/gangliosides) for Sendai virus (SeV). Accumulated published data reviewed here show different levels of expression of cell surface receptors for both viruses in different malignancies. Patients whose tumor cells have low or no expression of receptors for a specific oncolytic virus cannot be successfully treated with the virus. Recent published studies have revealed that an expression signature for immune genes is another important factor that determines the vulnerability of tumor cells to viral infection. In the future, a combination of expression signatures of immune and receptor genes could be used to find a set of oncolytic viruses that are more effective for specific malignancies.

Measles virus in cancer therapy

Over the last years, the development of viruses to treat cancer patients has re-gained considerable attention. A genetically modified herpesvirus, Talimogene laherparepvec, has already been authorized for the treatment of melanoma patients. Also recombinant measles virus (MeV) is developed as an oncolytic virus. Because of its high genetic flexibility, a number of different MeV strains have been the basis for the generation of targeted, armed, or shielded viruses that are highly specific for a given tumor target, more effective, or protected against serum neutralization. Such MeV have been extensively tested in vitro and in vivo, whereby remarkable oncolytic potency is accompanied by safety also in non-human primates. Therefore, MeV has been introduced into 19 different clinical trials and has reached phase II against two different tumor entities, multiple myeloma and ovarian carcinoma. Remarkably, one patient with advanced stage myeloma experienced long-term remission after treatment, visualizing the potency of this approach.

In vivo antitumor activity by dual stromal and tumor-targeted oncolytic measles viruses

The tumor stroma acts as a barrier that limits the efficacy of systemically administered oncolytic viruses (OV). We previously demonstrated that stromal-selective, retargeted oncolytic measles viruses (MVs) delay in vivo tumor progression. To further characterize the contribution of stromal targeting to MV's overall in vivo efficacy in an experimental cancer model, a dual targeted oncolytic measles virus (MV-CD46-muPA) able to simultaneously infect murine stromal (via murine uPAR) and human cancer (via CD46) cells was developed. MV-CD46-muPA infected, replicated, and induced cytotoxicity in both murine and human cancer cells. Viral infection was successfully transferred from stromal to tumor cells in vitro, leading to tumor cell oncolysis. Systemic administration of MV-CD46-muPA led to improved antitumor effects in colon (HT-29) cancer xenografts compared to vehicle or CD46 only targeted MVs. These effects were associated with improved tumor viral deposition, increased apoptosis, and decreases in murine stromal endothelial cells and fibroblasts. MV-CD46-muPA modulated cell cycle, survival, proliferation, and metabolic pathways, as determined by functional proteomic analysis of treated tumors. The above findings further validate the concept that dual stromal and tumor cell viral targeting enhances the therapeutic effects of systemically administered OVs and support further preclinical and clinical development of stromal directed virotherapies.

Development of Entry-Targeted Oncolytic Measles Viruses

This chapter describes the development of recombinant oncolytic measles viruses (MeV) that selectively enter and destroy tumor cells. The envelope of MeV is a favorable targeting substrate because receptor attachment and membrane fusion functions are separated on two proteins: the hemagglutinin (H) that binds receptors, and the fusion (F) protein that fuses the viral envelope with the cell membrane. The cell entry process, which depends on receptor recognition and occurs at the plasma membrane at neutral pH, results in the delivery of encapsidated genomes to the cytoplasm, where they replicate. Towards improving cancer specificity of oncolytic MeV, two types of cell entry targeting have been achieved. First, entry has been redirected through cancer-specific cell surface proteins. This was done by displaying specificity domains on H while also ablating binding to its natural receptors. Second, activation of the F protein was made dependent on secreted cancer proteases, while also interfering with F cleavage/activation by a ubiquitous intracellular protease. This chapter describes how entry-targeted MeV are produced: In short, gene cassettes with modified H or F coding regions are generated, and then introduced into the viral genome available on plasmid DNA. Such full-length genome plasmids are transfected in cell lines expressing, stably or transiently, the three viral proteins necessary for genome replication. Infectious centers form among these "rescue" cells, which allow isolation of clonal recombinant viruses. These are amplified, characterized in vitro, and then evaluated for their oncolytic activity in appropriate preclinical animal models.

High-Affinity DARPin Allows Targeting of MeV to Glioblastoma Multiforme in Combination with Protease Targeting without Loss of Potency

Measles virus (MeV) is naturally cytolytic by extensive cell-to-cell fusion. Vaccine-derived MeV is toxic for cancer cells and is clinically tested as oncolytic virus. To combine the potential of MeV with enhanced safety, different targeting strategies have been described. We generated a receptor-targeted MeV by using receptor-blind viral attachment protein genetically fused to designed ankyrin repeat protein (DARPin) binding domains specific for the epidermal growth factor receptor (EGFR). To reduce on-target toxicity for EGFR⁺ healthy cells, we used an engineered viral fusion protein activatable by tumor-associated matrix metalloproteases (MMPs) for additional protease targeting. The dual-targeted virus replicated exclusively on EGFR⁺/MMP⁺ tumor cells but was safe on healthy EGFR⁺ target cells, primary human keratinocytes. Nevertheless, glioblastoma and other tumor cells were efficiently killed by all targeted viruses, although replication and oncolysis were slower for protease-targeted MeV. In vivo, efficacy of EGFR-targeted MeV was virtually unimpaired, whereas also dual-targeted MeV showed significant intra-tumoral spread and efficacy and could be armed with a prodrug convertase. The use of DARPin-domains resulted in potent EGFR-targeted MeV and for the first time effective dual retargeting of an oncolytic virus, further enhancing tumor selectivity. Together with powerful cell-toxic genes, the application as highly tumor-specific platform is promising.

The Role of Interleukin-37 in the Pathogenesis of Allergic Diseases

Cytokines of the interleukin-1 (IL-1) family play an important role in the realization of the protective functions of innate immunity and are the key mediators involved in the pathogenesis of a wide range of diseases, including various manifestations of allergy. The IL-1 family includes more than 11 members. However, the functions of many of them remain to be elucidated. Recently, new members of the IL-1 family have been discovered. In 2000, several independent research groups reported the discovery of a new interleukin of this family, which was named IL-37, or IL-1F7 (according to the new nomenclature). IL-37 was assigned to the IL-1 family based on its structural similarity with other members of this family. The study of its biological properties showed that its activity changes in inflammatory diseases, such as rheumatoid arthritis, psoriasis, as well as allergic diseases (allergic rhinitis, bronchial asthma, and atopic dermatitis). However, unlike most members of the IL-1 family, IL-37 acts as a negative regulator of inflammation. Activation of IL-37 suppresses inflammation, resulting in the suppression of inflammatory cytokines and chemokines, which in turn prevents infiltration of pro-inflammatory cells, mainly eosinophils and neutrophils. The exact molecular and cellular mechanisms of the anti-inflammatory effect of IL-37 in the development of allergic diseases (AD) have not been fully studied. This review summarizes and analyzes the accumulated experimental data on the role of IL-37 in the pathogenesis of AD, such as allergic rhinitis, bronchial asthma, and atopic dermatitis.

DARPins: Promising Scaffolds for Theranostics

Monoclonal antibodies are the classical basis for targeted therapy, but the development of alternative binding proteins has made it possible to use non-immunoglobulin proteins as targeting modules. The advantages of DARPins, scaffold proteins based on ankyrin repeats, over antibodies are as follows: small size, stability over a wide range of temperatures and pH values, low aggregation tendency, and ease of production in heterologous expression systems. The differences in the structure of the paratope of DARPin and antibodies broaden the spectrum of target molecules, while the ease of creating hybrid fusion proteins allows one to obtain bispecific and multivalent constructs. In this article, we summarize recent data on the development of therapeutic and imaging compounds based on DARPins.

Concise Review: Targeting Cancer Stem Cells and Their Supporting Niche Using Oncolytic Viruses

Cancer stem cells (CSCs) have the capacity to self-renew and differentiate to give rise to heterogenous cancer cell lineages in solid tumors. These CSC populations are associated with metastasis, tumor relapse, and resistance to conventional anticancer therapies. Here, we focus on the use of oncolytic viruses (OVs) to target CSCs as well as the OV-driven interferon production in the tumor microenvironment (TME) that can repress CSC properties. We explore the ability of OVs to deliver combinations of immune-modulating therapeutic transgenes, such as immune checkpoint inhibitor antibodies. In particular, we highlight the advantages of virally encoded bi-specific T cell engagers (BiTEs) to not only target cell-surface markers on CSCs, but also tumor-associated antigens on contributing components of the surrounding TME and other cancer cells. We also highlight the crucial role of combination anticancer treatments, evidenced by synergy of OV-delivered BiTEs and chimeric-antigen receptor T cell therapy. Stem Cells 2019;37:716-723.

Combination of Oncolytic Measles Virus Armed With BNiP3, a Pro-apoptotic Gene and Paclitaxel Induces Breast Cancer Cell Death

Breast cancer is one of the major causes of cancer related mortality in women worldwide. Limitations of conventional anti-cancer therapies such as severe systemic side effects, narrow therapeutic index, non-specificity, and non-availability of drugs for all types of cancers has resulted in the development of various novel and targeted approaches. The use of viruses as oncolytic agents has gained momentum for the development of an efficient therapeutic platform. In this study, we have developed recombinant measles virus armed with BNiP3, a pro-apoptotic gene of human origin, as an oncolytic agent, and have demonstrated its ability to induce apoptosis in breast cancer cells in vitro. Studies have demonstrated the potential of using oncolytic viruses in combination with conventional therapies as an efficient anti-cancer regimen. We also have explored the synergistic potential of this virus in combination with paclitaxel, and a hydrazone derivative, H2 compound as an anti-cancer agent. MCF-7 and MDA-MB-231, human breast cancer cell lines were used for in vitro studies to evaluate toxic effects of armed virus, rMV-BNiP3 both as a standalone therapy and in combination with paclitaxel or H2 compound, a hydrazone derivative. Generation of armed virus was confirmed by detecting the viral transcript and protein expression, while its oncolytic potential by cell viability assays. Induction of apoptosis was demonstrated by fluorescence based caspase 3 activity and flow cytometry based Annexin V/PI staining. In the current study we have demonstrated the successful generation of an oncolytic measles virus armed with BNiP3 (rMV-BNiP3) and the induction of toxic effects in rMV-BNiP3 infected cells with a curious bias toward MDA-MB-231 cells as compared to MCF-7. Infection of breast cancer cells with rMV-BNiP3 caused induction of cell death, but the combination of rMV-BNiP3 with sub-lethal doses of both paclitaxel and H2 lowered the overall viability of cancer cells. As triple negative breast tumors are highly aggressive and resistant subtype of breast cancer with poor prognosis, comparative sensitivity of MDA-MB-231 cells toward this virus may potentially be used to develop a targeted therapy against triple negative breast cancer.

Virotherapy Research in Germany: From Engineering to Translation

Virotherapy is a unique modality for the treatment of cancer with oncolytic viruses (OVs) that selectively infect and lyse tumor cells, spread within tumors, and activate anti-tumor immunity. Various viruses are being developed as OVs preclinically and clinically, several of them engineered to encode therapeutic proteins for tumor-targeted gene therapy. Scientists and clinicians in German academia have made significant contributions to OV research and development, which are highlighted in this review paper. Innovative strategies for "shielding," entry or postentry targeting, and "arming" of OVs have been established, focusing on adenovirus, measles virus, parvovirus, and vaccinia virus platforms. Thereby, new-generation virotherapeutics have been derived. Moreover, immunotherapeutic properties of OVs and combination therapies with pharmacotherapy, radiotherapy, and especially immunotherapy have been investigated and optimized. German investigators are increasingly assessing their OV innovations in investigator-initiated and sponsored clinical trials. As a prototype, parvovirus has been tested as an OV from preclinical proof-of-concept up to first-in-human clinical studies. The approval of the first OV in the Western world, T-VEC (Imlygic), has further spurred the involvement of investigators in Germany in international multicenter studies. With the encouraging developments in funding, commercialization, and regulatory procedures, more German engineering will be translated into OV clinical trials in the near future.

Recent Progress in Gene Therapy for Ovarian Cancer

Ovarian cancer is the most lethal gynecological malignancy in developed countries. This is due to the lack of specific symptoms that hinder early diagnosis and to the high relapse rate after treatment with radical surgery and chemotherapy. Hence, novel therapeutic modalities to improve clinical outcomes in ovarian malignancy are needed. Progress in gene therapy has allowed the development of several strategies against ovarian cancer. Most are focused on the design of improved vectors to enhance gene delivery on the one hand, and, on the other hand, on the development of new therapeutic tools based on the restoration or destruction of a deregulated gene, the use of suicide genes, genetic immunopotentiation, the inhibition of tumour angiogenesis, the alteration of pharmacological resistance, and oncolytic virotherapy. In the present manuscript, we review the recent advances made in gene therapy for ovarian cancer, highlighting the latest clinical trials experience, the current challenges and future perspectives.

Recombinant viruses with other anti-cancer therapeutics: a step towards advancement of oncolytic virotherapy

Cancer as a disease is a multifaceted foe which sometimes succumbs to the prescribed treatment and sometimes develops resistance against various therapies. Conventional cancer therapies suffer from many limitations, the least of which is their specificity and systemic side effects. In a majority of cases, acquired mutations render the cancer cells resistant to therapy and lower the prognostic outcome. In the constant effort to devise a therapeutic moiety which can comprehensively eliminate cancer cells, oncolytic viruses provide an attractive avenue as they selectively infect and lyse cancer cells sparing normal cells from their effects. Viruses can be engineered for their host specificity and toxicity as a promising anti-cancer tool. As it is essential to devise a strategy to address all targets involved in cancer development and progression, the idea of using oncolytic viruses with enhanced anti-cancer activity through arming with foreign genes gained merit and is showing promising advent in clinical studies. The use of oncolytic viruses as an agent of combination therapy for cancer treatment also gained much attention in the recent past. This review focuses on the emerging role of oncolytic viruses as vital components of anti-cancer regimen presenting a new dimension in an ever-changing cancer therapy scenario.