Determinants of the efficacy of viro-immunotherapy: A review

Advancing ORFV-Based Therapeutics to the Clinical Stage

The Orf virus (ORFV) is the prototype member of the parapoxvirus family and has long been recognized for its robust immunogenicity, favourable safety profile and its ability to stimulate both cellular and humoural immune responses without inducing significant anti-vector immunity. Despite these inherent advantages, early applications of ORFV-based technologies were limited by challenges in manufacturing scalability and uncertainties regarding clinical safety in humans. However, recent breakthroughs have transformed this therapeutic landscape. A landmark achievement is the development of Prime-2-CoV, an ORFV-based anti-COVID-19 vaccine that has advanced into human clinical trials, providing the first clinical evidence of live ORFV's feasibility, safety and immunogenicity. This milestone, together with the establishment of a good manufacturing practice (GMP)-compliant production process and comprehensive preclinical evaluations, has laid a robust foundation for broader clinical applications of ORFV-based therapeutics. Moreover, the use of ORFV as an oncolytic virus therapy has shown promising results, effectively converting immunologically 'cold' tumours into 'hot' ones, underscoring its versatility as a therapeutic platform. In this review, we critically assess recent advances in ORFV-based therapeutics, with a particular focus on vaccine development and oncolytic virotherapy (OVT). We thoroughly discuss the milestones and impact of the first ORFV-based clinical trial, outline strategies for optimizing the technology and provide insights into overcoming remaining challenges. Collectively, these advancements position ORFV as a highly promising and versatile platform for next-generation prophylactic and therapeutic interventions in both human and veterinary medicine, while also providing a roadmap for future innovations.

Development of viral infectious clones and their applications based on yeast and bacterial artificial chromosome platforms

Infectious Clones represent a foundational technique in the field of reverse genetics, allowing for the construction and manipulation of full-length viral genomes. The main methods currently used for constructing viral infectious clones include Transformation-associated recombination (TAR), which is based on Yeast Artificial Chromosome (YAC) and Bacterial Artificial Chromosome (BAC). The YAC and BAC systems are powerful tools that enable the clones and manipulation of large DNA fragments, making them well-suited for the construction of full-length viral genomes. These methods have been successfully applied to construct infectious clones for a wide range of viruses, including coronaviruses, herpesviruses, flaviviruses and baculoviruses. The rescued recombinant viruses from these infectious clones have been widely used in various research areas, such as vaccine development, antiviral drug screening, pathogenesis and virulence studies, gene therapy and vector design. However, as different viruses possess unique biological characteristics, the challenge remains in how to rapidly obtain infectious clones for future research. In summary, this review introduced the development and applications of infectious clones, with a focus on the YAC, BAC and combined YAC-BAC technologies. We emphasize the importance of these platforms in various research areas and aim to provide deeper insights that can advance the platform and broaden its application horizons.

Innovations in cancer immunotherapy: A comprehensive overview of recent breakthroughs and future directions

A major advance in cancer treatment has been the development and refinement of cancer immunotherapy. The discovery of immunotherapies for a wide range of cancers has revolutionized cancer treatment paradigms. Despite relapse or refractory disease, immunotherapy approaches can prolong the life expectancy of metastatic cancer patients. Multiple therapeutic approaches and agents are currently being developed to manipulate various aspects of the immune system. Oncolytic viruses, cancer vaccines, adoptive cell therapies, monoclonal antibodies, cytokine therapies, and inhibitors of immune checkpoints have all proven successful in clinical trials. There are several types of immunotherapeutic approaches available for treating cancer, and others are being tested in preclinical and clinical settings. Immunotherapy has proven successful, and many agents and strategies have been developed to improve its effectiveness. The purpose of this article is to present a comprehensive overview of current immunotherapy approaches used to treat cancer. Cancer immunotherapy advancements, emerging patterns, constraints, and potential future breakthroughs are also discussed.

Single intravenous administration of oncolytic adenovirus TILT-123 results in systemic tumor transduction and immune response in patients with advanced solid tumors

BACKGROUND

A limitation of approved oncolytic viruses is their requirement for intratumoral (i.t.) injection. TILT-123 (igrelimogene litadenorepvec, Ad5/3-E2F-D24-hTNFα-IRES-hIL-2) is a chimeric oncolytic adenovirus suitable for intravenous (i.v.) delivery due to its capsid modification and dual selectivity devices. It is armed with tumor necrosis alpha and interleukin-2 for promoting T-cell activation and lymphocyte trafficking to tumors, thereby enhancing the antitumor immune response. Here, we present the findings after a single i.v. administration of TILT-123 in three phase I dose escalation clinical trials.

METHODS

Patients with advanced solid tumors initially received a single i.v. dose of TILT-123 ranging from 3 × 109 to 4 × 1012 viral particles (VP). Blood was collected at baseline, 1, 16, and 192 h (7 days) post-treatment for bioavailability and serum analysis. Tumor biopsies were collected prior to treatment and 7 days post-treatment for analysis of viral presence and immunological effects. Patients did not receive any other cancer therapies during this period.

RESULTS

Across all three trials (TUNIMO, TUNINTIL, and PROTA), 52 total patients were treated with i.v. TILT-123. Overall, TILT-123 was found to be well-tolerated, with no dose-limiting toxicities observed. Post-treatment tumor biopsies showed expression of viral genes, presence of TILT-123 adenovirus proteins or DNA, and changes in immune cell infiltration from baseline. Increased virus dose did not lead to increased virus detection in tumors. Median overall survival was longer in patients with confirmed presence of TILT-123 in post-treatment biopsies (280 versus 190 days, p = 0.0405).

CONCLUSION

TILT-123 demonstrated safety and significant intratumoral immunomodulation following a single i.v. administration, warranting further investigation.

TRIAL REGISTRATIONS

TUNIMO-NCT04695327. Registered 4 January 2021, https://clinicaltrials.gov/study/NCT04695327 . TUNINTIL-NCT04217473. Registered 19 December 2019, https://clinicaltrials.gov/study/NCT04217473 . PROTA-NCT05271318. Registered 4 February 2022, https://clinicaltrials.gov/study/NCT05271318 .

Immunogenic cell death-based oncolytic virus therapy: A sharp sword of tumor immunotherapy

Tumor immunotherapy, especially immune checkpoint inhibitors (ICIs), has been applied in clinical practice, but low response to immune therapies remains a thorny issue. Oncolytic viruses (OVs) are considered promising for cancer treatment because they can selectively target and destroy tumor cells followed by spreading to nearby tumor tissues for a new round of infection. Immunogenic cell death (ICD), which is the major mechanism of OVs' anticancer effects, is induced by endoplasmic reticulum stress and reactive oxygen species overload after virus infection. Subsequent release of specific damage-associated molecular patterns (DAMPs) from different types of tumor cells can transform the tumor microenvironment from "cold" to "hot". In this paper, we broadly define ICD as those types of cell death that is immunogenic, and describe their signaling pathways respectively. Focusing on ICD, we also elucidate the advantages and disadvantages of recent combination therapies and their future prospects.

Liposomes-Encapsulating Double-Stranded Nucleic Acid (Poly I:C) for Head and Neck Cancer Treatment

Polyriboinosinic acid-polyribocytidylic acid (Poly I:C) serves as a synthetic mimic of viral double-stranded dsRNA, capable of inducing apoptosis in numerous cancer cells. Despite its potential, therapeutic benefits, the application of Poly I:C has been hindered by concerns regarding toxicity, stability, enzymatic degradation, and undue immune stimulation, leading to autoimmune disorders. To address these challenges, encapsulation of antitumor drugs within delivery systems such as cationic liposomes is often employed to enhance their efficacy while minimizing dosages. In this study, we investigated the potential of cationic liposomes to deliver Poly I:C into the Head and Neck 12 (HN12) cell line to induce apoptosis in the carcinoma cells and tumor model. Cationic liposomes made by the hydrodynamic focusing method surpass traditional methods by offering a continuous flow-based approach for encapsulating genes, which is ideal for efficient tumor delivery. DOTAP liposomes efficiently bind Poly I:C, confirmed by transmission electron microscopy images displaying their spherical morphology. Liposomes are easily endocytosed in HN12 cells, suggesting their potential for therapeutic gene and drug delivery in head and neck squamous carcinoma cells. Activation of apoptotic pathways involving MDA5, RIG-I, and TLR3 is evidenced by upregulated caspase-3, caspase-8, and IRF3 genes upon endocytosis of Poly(I:C)-encapsulated liposomes. Therapeutic evaluations revealed significant inhibition of tumor growth with Poly I:C liposomes, indicating the possibility of MDA5, RIG-I, and TLR3-induced apoptosis pathways via Poly I:C liposomes in HN12 xenografts in J:NU mouse models. Comparative histological analysis underscores enhanced cell death with Poly I:C liposomes, warranting further investigation into the precise mechanisms of apoptosis and inflammatory cytokine response in murine models for future research.

Enhanced cellular therapy: revolutionizing adoptive cellular therapy

Enhanced cellular therapy has emerged as a novel concept following the basis of cellular therapy. This treatment modality applied drugs or biotechnology to directly enhance or genetically modify cells to enhance the efficacy of adoptive cellular therapy (ACT). Drugs or biotechnology that enhance the killing ability of immune cells include immune checkpoint inhibitors (ICIs) / antibody drugs, small molecule inhibitors, immunomodulatory factors, proteolysis targeting chimera (PROTAC), oncolytic virus (OV), etc. Firstly, overcoming the inhibitory tumor microenvironment (TME) can enhance the efficacy of ACT, which can be achieved by blocking the immune checkpoint. Secondly, cytokines or cytokine receptors can be expressed by genetic engineering or added directly to adoptive cells to enhance the migration and infiltration of adoptive cells to tumor cells. Moreover, multi-antigen chimeric antigen receptors (CARs) can be designed to enhance the specific recognition of tumor cell-related antigens, and OVs can also stimulate antigen release. In addition to inserting suicide genes into adoptive cells, PROTAC technology can be used as a safety switch or degradation agent of immunosuppressive factors to enhance the safety and efficacy of adoptive cells. This article comprehensively summarizes the mechanism, current situation, and clinical application of enhanced cellular therapy, describing potential improvements to adoptive cellular therapy.

Comparison between intratumoral and intravenously administered oncolytic virus therapy with Newcastle disease virus in a xenograft murine model for pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a poor clinical prognosis and is usually a metastatic disease. In the last decades, oncolytic viro-immunotherapy has shown a promise as treatment strategy with encouraging results for a variety of tumors. Newcastle Disease Virus (NDV) is an oncolytic virus which selectively infects and damages tumors either by directly killing tumor cells or by promoting an anti-tumor immune response. Several studies have demonstrated that NDV strains with a multi-basic cleavage site (MBCS) in the fusion protein (F) have increased anti-tumor efficacy upon intratumoral injection in murine tumor models. However, intravenous injections, in which the oncolytic virus spreads systemically, could be more beneficial to treat metastasized PDAC in addition to the primary tumor. In this study, we compared the oncolytic efficacy and safety of intratumoral and intravenous injections with NDV containing an MBCS in F (NDV F3aa) in an immune deficient murine xenograft (BxPC3) model for PDAC. In this model, both intratumoral and intravenous injections with NDV F3aa induced anti-tumor efficacy as measured at 10 days after the first injection. Upon intravenous injection virus was detected in some of the tumors, indicating the systemic spread of the virus. Upon both treatments, mice did not display weight loss or abnormalities and treated mice did not secrete virus to the environment. These data demonstrate that intravenous injections of NDV F3aa can be applicable to treat metastasized cancers in immune deficient hosts without inflicting adverse effects.