Therapeutic Applications for Oncolytic Self-Replicating RNA Viruses

Self-amplifying RNA virus vectors for drug delivery

INTRODUCTION

Viral vectors have proven useful for delivering genetic information, such as drugs and vaccines, for therapeutic and prophylactic interventions. Self-amplifying RNA viruses possess the special feature of high-level RNA amplification in the host cell cytoplasm providing high antigen production against infectious pathogens and various types of cancers, and expression of anti-tumor genes, toxic genes, and immunostimulatory genes.

AREAS COVERED

Self-amplifying RNA viral vectors have been evaluated in animal models and clinical trials for immune responses and protection against challenges with pathogenic infectious agents and tumor cells. Likewise, immune responses, tumor regression, and tumor eradication have been monitored in preclinical and clinical settings. The literature search used in the review is based on PubMed and clinical trial/biotechnology company websites up until September 2024.

EXPERT OPINION

Self-amplifying RNA viruses have elicited strong immune responses and vaccine efficacy in animal models and humans leading to the approval of the vesicular stomatitis virus-based vaccine against Ebola virus disease in both the US and Europe. Moreover, therapeutic and prophylactic efficacy has been demonstrated in animal tumor models and cancer patients. Self-amplifying RNA viruses have also been evaluated in mouse models for neurological disorders.

Molecular Pathology Methods to Characterize Biodistribution and Pharmacodynamics of the Oncolytic Virus VSV-GP in a Nonclinical Tumor Model

Replication-competent oncolytic virus (OV) therapies are a promising new modality for cancer treatment. However, they pose unique challenges for preclinical assessment, due in part to their tumor specificity and ability to self-replicate in vivo. Understanding biodistribution, immune cell responses, and potential effects of intratumoral replication on these outcomes are important aspects of the nonclinical profile for OVs. Herein, a single intravenous dose of vesicular stomatitis virus pseudotyped with the glycoprotein of lymphocytic choriomeningitis virus (VSV-GP), or a cargo-expressing variant (VSV-GP-[cargo]), was examined in both tumor-free and CT26.CL25.IFNAR-/- syngeneic tumor-bearing mouse models. Biodistribution and immune cell responses were characterized using different molecular pathology methods, including a strand-specific in situ hybridization method to differentiate administered viral genomes from replicated or transcribed viral anti-genome RNA. We identified distinct patterns of viral biodistribution and replication across tumor and nontumor sites but no major differences in biodistribution, off-tumor cell tropism, or immune cell responses between tumor-free and tumor-bearing mouse models. Our findings characterize key cellular changes following systemic exposure to VSV-GP, provide a better understanding of a nonclinical permissive tumor model for OV assessment, and demonstrate how current molecular pathology methods can provide a bridge between traditional biodistribution and pathology readouts.

Potential Consequences of the Use of Adipose-Derived Stem Cells in the Treatment of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) ranks as the most prevalent of primary liver cancers and stands as the third leading cause of cancer-related deaths. Early-stage HCC can be effectively managed with available treatment modalities ranging from invasive techniques, such as liver resection and thermoablation, to systemic therapies primarily employing tyrosine kinase inhibitors. Unfortunately, these interventions take a significant toll on the body, either through physical trauma or the adverse effects of pharmacotherapy. Consequently, there is an understandable drive to develop novel HCC therapies. Adipose-derived stem cells (ADSCs) are a promising therapeutic tool. Their facile extraction process, coupled with the distinctive immunomodulatory capabilities of their secretome, make them an intriguing subject for investigation in both oncology and regenerative medicine. The factors they produce are both enzymes affecting the extracellular matrix (specifically, metalloproteinases and their inhibitors) as well as cytokines and growth factors affecting cell proliferation and invasiveness. So far, the interactions observed with various cancer cell types have not led to clear conclusions. The evidence shows both inhibitory and stimulatory effects on tumor growth. Notably, these effects appear to be dependent on the tumor type, prompting speculation regarding their potential inhibitory impact on HCC. This review briefly synthesizes findings from preclinical and clinical studies examining the effects of ADSCs on cancers, with a specific focus on HCC, and emphasizes the need for further research.

Therapeutic bacteria and viruses to combat cancer: double-edged sword in cancer therapy: new insights for future

Cancer, ranked as the second leading cause of mortality worldwide, leads to the death of approximately seven million people annually, establishing itself as one of the most significant health challenges globally. The discovery and identification of new anti-cancer drugs that kill or inactivate cancer cells without harming normal and healthy cells and reduce adverse effects on the immune system is a potential challenge in medicine and a fundamental goal in Many studies. Therapeutic bacteria and viruses have become a dual-faceted instrument in cancer therapy. They provide a promising avenue for cancer treatment, but at the same time, they also create significant obstacles and complications that contribute to cancer growth and development. This review article explores the role of bacteria and viruses in cancer treatment, examining their potential benefits and drawbacks. By amalgamating established knowledge and perspectives, this review offers an in-depth examination of the present research landscape within this domain and identifies avenues for future investigation.

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.

Immune Modulation of Innate and Adaptive Responses Restores Immune Surveillance and Establishes Antitumor Immunologic Memory

Current immunotherapies have proven effective in strengthening antitumor immune responses, but constant opposing signals from tumor cells and the surrounding microenvironment eventually lead to immune escape. We hypothesized that in situ release of antigens and regulation of both the innate and adaptive arms of the immune system would provide a robust and long-term antitumor effect by creating immunologic memory against tumors. To achieve this, we developed CARG-2020, a genetically modified virus-like vesicle (VLV) that is a self-amplifying RNA with oncolytic capacity and encodes immune regulatory genes. CARG-2020 carries three immune modulators: (i) the pleiotropic antitumor cytokine IL12, in which the subunits (p35 and p40) are tethered together; (ii) the extracellular domain (ECD) of the protumor IL17RA, which serves as a dominant-negative antagonist; and (iii) a shRNA targeting PD-L1. Using a mouse model of ovarian cancer, we demonstrated the oncolytic effect and immune-modulatory capacities of CARG-2020. By enhancing IL12 and blocking IL17 and PD-L1, CARG-2020 successfully reactivated immune surveillance by promoting M1, instead of M2, macrophage differentiation, inhibiting MDSC expansion and establishing a potent CD8+ T cell-mediated antitumoral response. Furthermore, we demonstrated that this therapeutic approach provided tumor-specific and long-term protection against the establishment of new tumors. Our results provide a rationale for the further development of this platform as a therapeutic modality for ovarian cancer patients to enhance antitumor responses and prevent a recurrence.

Engineering Non-Human RNA Viruses for Cancer Therapy

Alongside the development and progress in cancer immunotherapy, research in oncolytic viruses (OVs) continues advancing novel treatment strategies to the clinic. With almost 50 clinical trials carried out over the last decade, the opportunities for intervention using OVs are expanding beyond the old-fashioned concept of "lytic killers", with promising breakthrough therapeutic strategies focused on leveraging the immunostimulatory potential of different viral platforms. This review presents an overview of non-human-adapted RNA viruses engineered for cancer therapy. Moreover, we describe the diverse strategies employed to manipulate the genomes of these viruses to optimize their therapeutic capabilities. By focusing on different aspects of this particular group of viruses, we describe the insights into the promising advancements in the field of virotherapy and its potential to revolutionize cancer treatment.

Immune modulation of innate and adaptive responses restores immune surveillance and establishes anti-tumor immunological memory

Current immunotherapies have proven effective in strengthening anti-tumor immune responses but constant opposing signals from tumor cells and surrounding microenvironment eventually lead to immune escape. We hypothesize that in situ release of antigens and regulation of both the innate and adaptive arms of the immune system will provide a robust and long-term anti-tumor effect by creating immunological memory against the tumor. To achieve this, we developed CARG-2020, a virus-like-vesicle (VLV). It is a genetically modified and self-amplifying RNA with oncolytic capacity and encodes immune regulatory genes. CARG-2020 carries three transgenes: 1 ) the pleiotropic antitumor cytokine IL-12 in which the subunits (p35 and p40) are tethered together; 2) the extracellular domain (ECD) of the pro- tumor IL-17RA, which can serve as a dominant negative antagonist; and 3) shRNA for PD-L1. Using a mouse model of ovarian cancer, we demonstrate the oncolytic effect and immune modulatory capacities of CARG-2020. By enhancing IL-12 and blocking IL-17 and PD-L1, CARG-2020 successfully reactivates immune surveillance by promoting M1 instead of M2 macrophage differentiation, inhibiting MDSC expansion, and establishing a potent CD8+ T cell mediated anti-tumoral response. Furthermore, we demonstrate that this therapeutic approach provides tumor-specific and long-term protection preventing the establishment of new tumors. Our results provide rationale for the further development of this platform as a therapeutic modality for ovarian cancer patients to enhance the anti-tumor response and to prevent recurrence.

Viral vectors engineered for gene therapy

Gene therapy has seen major progress in recent years. Viral vectors have made a significant contribution through efficient engineering for improved delivery and safety. A large variety of indications such as cancer, cardiovascular, metabolic, hematological, neurological, muscular, ophthalmological, infectious diseases, and immunodeficiency have been targeted. Viral vectors based on adenoviruses, adeno-associated viruses, herpes simplex viruses, retroviruses including lentiviruses, alphaviruses, flaviviruses, measles viruses, rhabdoviruses, Newcastle disease virus, poxviruses, picornaviruses, reoviruses, and polyomaviruses have been used. Proof-of-concept has been demonstrated for different indications in animal models. Therapeutic efficacy has also been achieved in clinical trials. Several viral vector-based drugs have been approved for the treatment of cancer, and hematological, metabolic, and neurological diseases. Moreover, viral vector-based vaccines have been approved against COVID-19 and Ebola virus disease.

Tumor resident, TRA anti-viral CDR3 chemical sequence motifs are associated with a better breast cancer outcome

While for certain cancers, such as cervical cancer, the link to viral infections is very strong and very clear, other cancers represent a history of links to viral infections that are either co-morbidities or drive the cancer in ways that are not yet fully understood, for example the "hit and run" possibility. To further understand the connection of viral infections and the progress of breast cancer, we identified the chemical features of known anti-viral, T-cell receptor alpha chain (TRA) complementarity determining region-3 (CDR3) amino acid sequences among the CDR3s of breast cancer patient TRA recombinations and assessed the association of those features with patient outcomes. The application of this novel paradigm indicated consistent associations of tumor-derived, anti-CMV CDR3 chemical sequence motifs with better breast cancer patient outcomes but did not indicate an opportunity to establish risk stratifications for other cancer types. Interestingly, breast cancer samples with no detectable TRA recombinations represented a better outcome than samples with the non-anti-CMV CDR3s, further adding to a rapidly developing series of results allowing a distinction between positive and possibly harmful cancer immune responses.