Targeted Delivery of IL-12 Adjuvants Immunotherapy by Oncolytic Viruses

Gene Immunotherapy of Colon Carcinoma with IL-2 and IL-12 Using Gene Electrotransfer

Gene immunotherapy has become an important approach in the treatment of cancer. One example is the introduction of genes encoding immunostimulatory cytokines, such as interleukin 2 and interleukin 12, which stimulate immune cells in tumours. The aim of our study was to determine the effects of gene electrotransfer of plasmids encoding interleukin 2 and interleukin 12 individually and in combination in the CT26 murine colon carcinoma cell line in mice. In the in vitro experiment, the pulse protocol that resulted in the highest expression of IL-2 and IL-12 mRNA and proteins was used for the in vivo part. In vivo, tumour growth delay and also complete response were observed in the group treated with the plasmid combination. Compared to the control group, the highest levels of various immunostimulatory cytokines and increased immune infiltration were observed in the combination group. Long-term anti-tumour immunity was observed in the combination group after tumour re-challenge. In conclusion, our combination therapy efficiently eradicated CT26 colon carcinoma in mice and also generated strong anti-tumour immune memory.

Innovative retargeted oncolytic herpesvirus against nectin4-positive cancers

Nectin4 is a recently discovered tumor associated antigen expressed in cancers that constitute relevant unmet clinical needs, including the undruggable triple negative breast cancer, pancreatic ductal carcinoma, bladder/urothelial cancer, cervical cancer, lung carcinoma and melanoma. So far, only one nectin4-specific drug-Enfortumab Vedotin-has been approved and the clinical trials that test novel therapeutics are only five. Here we engineered R-421, an innovative retargeted onco-immunotherapeutic herpesvirus highly specific for nectin4 and unable to infect through the natural herpes receptors, nectin1 or herpesvirus entry mediator. In vitro, R-421 infected and killed human nectin4-positive malignant cells and spared normal cells, e.g., human fibroblasts. Importantly from a safety viewpoint, R-421 failed to infect malignant cells that do not harbor nectin4 gene amplification/overexpression, whose expression level was moderate-to-low. In essence, there was a net threshold value below which cells were spared from infection, irrespective of whether they were malignant or normal; the only cells that R-421 targeted were the malignant overexpressing ones. In vivo, R-421 decreased or abolished the growth of murine tumors made transgenic for human nectin4 and conferred sensitivity to immune checkpoint inhibitors in combination therapies. Its efficacy was augmented by the cyclophosphamide immunomodulator and decreased by depletion of CD8-positive lymphocytes, arguing that it was in part T cell-mediated. R-421 elicited in-situ vaccination that protected from distant challenge tumors. This study provides proof-of-principle specificity and efficacy data justifying nectin4-retargeted onco-immunotherapeutic herpesvirus as an innovative approach against a number of difficult-to-drug clinical indications.

The V protein in oncolytic Newcastle disease virus promotes HepG2 hepatoma cell proliferation at the single-cell level

BACKGROUND

Newcastle disease virus (NDV) is an oncolytic virus that can inhibit cancer cell proliferation and kill cancer cells. The NDV nonstructural V protein can regulate viral replication; however, whether the V protein contributes to NDV oncolysis is unclear.

RESULTS

This study revealed that NDV inhibited tumor cell proliferation and that V protein expression promoted the proliferation of HepG2 cells, as determined at the single-cell level. In addition, to identify the regulatory mechanism of the V protein in HepG2 cells, transcriptome sequencing was performed and indicated that the expression/activation of multiple cell proliferation-related genes/signaling pathways were changed in cells overexpressing the V protein. Hence, the MAPK and WNT signaling pathways were selected for verification, and after blocking these two signaling pathways with inhibitors, the V protein promotion of cell proliferation was found to be attenuated.

CONCLUSIONS

The results showed that the V protein regulated the proliferation of cancer cells through multiple signaling pathways, providing valuable references for future studies on the mechanism by which the V protein regulates cancer cell proliferation.

Oncolytic Adenoviruses Armed with Co-Stimulatory Molecules for Cancer Treatment

In clinical trials, adenovirus vectors (AdVs) are commonly used platforms for human gene delivery therapy. High genome capacity and flexibility in gene organization make HAdVs suitable for cloning. Recent advancements in molecular techniques have influenced the development of genetically engineered adenovirus vectors showing therapeutic potential. Increased molecular understanding of the benefits and limitations of HAdVs in preclinical research and clinical studies is a crucial point in the engineering of refined oncolytic vectors. This review presents HAdV species (A-G) used in oncotherapy. We describe the adenovirus genome organizations and modifications, the possibilities oncolytic viruses offer, and their current limitations. Ongoing and ended clinical trials based on oncolytic adenoviruses are presented. This review provides a broad overview of the current knowledge of oncolytic therapy. HAdV-based strategies targeting tumors by employing variable immune modifiers or delivering immune stimulatory factors are of great promise in the field of immune oncologyy This approach can change the face of the fight against cancer, supplying the medical tools to defeat tumors more selectively and safely.

An armed oncolytic virus enhances the efficacy of tumor-infiltrating lymphocyte therapy by converting tumors to artificial antigen-presenting cells in situ

The full potential of tumor-infiltrating lymphocyte (TIL) therapy has been hampered by the inadequate activation and low persistence of TILs, as well as inefficient neoantigen presentation by tumors. We transformed tumor cells into artificial antigen-presenting cells (aAPCs) by infecting them with a herpes simplex virus 1 (HSV-1)-based oncolytic virus encoding OX40L and IL12 (OV-OX40L/IL12) to provide local signals for optimum T cell activation. The infected tumor cells displayed increased expression of antigen-presenting cell-related markers and induced enhanced T cell activation and killing in coculture with TILs. Combining OV-OX40L/IL12 and TIL therapy induced complete tumor regression in patient-derived xenograft and syngeneic mouse tumor models and elicited an antitumor immunological memory. In addition, the combination therapy produced aAPC properties in tumor cells, activated T cells, and reprogrammed macrophages to a more M1-like phenotype in the tumor microenvironment. This combination strategy unleashes the full potential of TIL therapy and warrants further evaluation in clinical studies.

Chitosan particle stabilized Pickering emulsion/interleukin-12 adjuvant system for Pgp3 subunit vaccine elicits immune protection against genital chlamydial infection in mice

Considering the shortcomings in current chlamydia infection control strategies, a major challenge in curtailing infection is the implementation of an effective vaccine. The immune response induced by C. trachomatis plasmid encoded Pgp3 was insufficient against C. trachomatis infection, which requires adjuvant applications to achieve the robust immune response induced by Pgp3. There is increasing promising in developing adjuvant systems relying on the delivery potential of Pickering emulsions and the immunomodulatory effects of interleukin (IL)-12. Here, owing to the polycationic nature, chitosan particles tended to absorb on the oil/water interphase to prepare the optimized chitosan particle-stabilized Pickering emulsion (CSPE), which was designed as a delivery system for Pgp3 protein and IL-12. Our results showed that the average droplets size of CSPE was 789.47 ± 44.26 nm after a series of optimizations and about 90% antigens may be absorbed by CSPE owing to the positively charged surface (33.2 ± 3mV), and CSPE promoted FITC-BSA proteins uptake by macrophages. Furthermore, as demonstrated by Pgp3-specific antibody production and cytokine secretion, CSPE/IL-12 system enhanced significantly higher levels of Pgp3-specific IgG, IgG1, IgG2a, sIgA and significant cytokines secretion of IFN-γ, IL-2, TNF-α, IL-4. Similarly, vaginal chlamydial shedding and hydrosalpinx pathologies were markedly reduced in mice immunized with Pgp3/CSPE/IL-12. Collectively, vaccination with Pgp3/CSPE/IL-12 regimen elicited robust cellular and humoral immune response in mice resulting in an obvious reduction of live chlamydia load in the vaginal and inflammatory pathologies in the oviduct, which further propells the development of vaccines against C. trachomatis infection.

Development of Molecular Mechanisms and Their Application on Oncolytic Newcastle Disease Virus in Cancer Therapy

Cancer is caused by the destruction or mutation of cellular genetic materials induced by environmental or genetic factors. It is defined by uncontrolled cell proliferation and abnormality of the apoptotic pathways. The majority of human malignancies are characterized by distant metastasis and dissemination. Currently, the most common means of cancer treatment include surgery, radiotherapy, and chemotherapy, which usually damage healthy cells and cause toxicity in patients. Targeted therapy is an effective tumor treatment method with few side effects. At present, some targeted therapeutic drugs have achieved encouraging results in clinical studies, but finding an effective solution to improve the targeting and delivery efficiency of these drugs remains a challenge. In recent years, oncolytic viruses (OVs) have been used to direct the tumor-targeted therapy or immunotherapy. Newcastle disease virus (NDV) is a solid oncolytic agent capable of directly killing tumor cells and increasing tumor antigen exposure. Simultaneously, NDV can trigger the proliferation of tumor-specific immune cells and thus improve the therapeutic efficacy of NDV in cancer. Based on NDV’s inherent oncolytic activity and the stimulation of antitumor immune responses, the combination of NDV and other tumor therapy approaches can improve the antitumor efficacy while reducing drug toxicity, indicating a broad application potential. We discussed the biological properties of NDV, the antitumor molecular mechanisms of oncolytic NDV, and its application in the field of tumor therapy in this review. Furthermore, we presented new insights into the challenges that NDV will confront and suggestions for increasing NDV’s therapeutic efficacy in cancer.

Towards a Precision Medicine Approach and In Situ Vaccination against Prostate Cancer by PSMA-Retargeted oHSV

Prostate specific membrane antigen (PSMA) is a specific high frequency cell surface marker of prostate cancers. Theranostic approaches targeting PSMA show no major adverse effects and rule out off-tumor toxicity. A PSMA-retargeted oHSV (R-405) was generated which both infected and was cytotoxic exclusively for PSMA-positive cells, including human prostate cancer LNCaP and 22Rv1 cells, and spared PSMA-negative cells. R-405 in vivo efficacy against LLC1-PSMA and Renca-PSMA tumors consisted of inhibiting primary tumor growth, establishing long-term T immune response, immune heating of the microenvironment, de-repression of the anti-tumor immune phenotype, and sensitization to checkpoint blockade. The in situ vaccination protected from distant challenge tumors, both PSMA-positive and PSMA-negative, implying that it was addressed also to LLC1 tumor antigens. PSMA-retargeted oHSVs are a precision medicine tool worth being additionally investigated in the immunotherapeutic and in situ vaccination landscape against prostate cancers.

Genotype of Immunologically Hot or Cold Tumors Determines the Antitumor Immune Response and Efficacy by Fully Virulent Retargeted oHSV

We report on the efficacy of the non-attenuated HER2-retargeted oHSV named R-337 against the immunologically hot CT26-HER2 tumor, and an insight into the basis of the immune protection. Preliminarily, we conducted an RNA immune profiling and immune cell content characterization of CT26-HER2 tumor in comparison to the immunologically cold LLC1-HER2 tumor. CT26-HER2 tumor was implanted into HER2-transgenic BALB/c mice. Hallmarks of R-337 effects were the protection from primary tumor, long-term adaptive vaccination directed to both HER2 and CT26-wt cell neoantigens. The latter effect differentiated R-337 from OncoVEXGM-CSF. As to the basis of the immune protection, R-337 orchestrated several changes to the tumor immune profile, which cumulatively reversed the immunosuppression typical of this tumor (graphical abstract). Thus, Ido1 (inhibitor of T cell anticancer immunity) levels and T regulatory cell infiltration were decreased; Cd40 and Cd27 co-immunostimulatory markers were increased; the IFNγ cascade was activated. Of note was the dampening of IFN-I response, which we attribute to the fact that R-337 is fully equipped with genes that contrast the host innate response. The IFN-I shut-down likely favored viral replication and the expression of the mIL-12 payload, which, in turn, boosted the antitumor response. The results call for a characterization of tumor immune markers to employ oncolytic herpesviruses more precisely.

Immunomodulatory Arming Factors-The Current Paradigm for Oncolytic Vectors Relies on Immune Stimulating Molecules

The dogma of engineering oncolytic viral vectors has shifted from emphasizing the viral lysis of individual cancer cells to the recruitment and coordination of the adaptive immune system to clear the tumor. To accomplish this, researchers have been adding several classes of transgenes to their preferred viral platforms. The most prevalent of these include antibodies and targeting moieties, interleukins and cytokines, and genes which rely on small molecule co-administration for tumor killing. Most current vectors rely exclusively on one of these types of transgenes to elicit the desired immune response to clear tumors, but are not mutually exclusive, with several larger OVs armed with several of these factors. The common theme of emerging armed vectors is to simply initiate or enhance infiltration of effector CD8+ T cells to clear the tumor locally at OV infection sites, and systemically throughout the body where the OV has not infected tumor cells. The precision of oncolytic vectors to target a cell type or tissue remains its key advantage over small-molecule drugs. Unlike chemo- and other drug therapies, viral vectors can be made to specifically infect and grow within tumor cells. This ensures localized expression of the therapeutic transgene to the diseased tissue, thereby limiting systemic toxicity. This review will examine the immunomodulating transgenes of current OVs, describe their general effect on the immune system, and provide the rationale for each vector's use in clearing its targeted tumor.