Efficacy Of Oncolytic Vaccinia Virus Research Articles

Oncolytic vaccinia virus acts synergistically with anti-PD-L1 antibody to enhance the killing of colon cancer cells by CD8+ T cells

Both oncolytic vaccinia virus (OVV) and anti-PD-L1 antibody hold promise in cancer immunotherapy. Herein, we aimed to explore the possible synergistic effects of OVV and anti-PD-L1 on the growth and metastasis of colon cancer (CC) in mouse models. Microarray profiling of CC-related genes was first conducted. Expression of PD-L1 in CC tissues was predicted by TCGA and verified by flow cytometry and RT-qPCR. Then, mouse CC cell lines stably carrying luciferase MC38-luc and CT26-luc were infected with recombinant double-deleted vaccinia virus (vvDD) to evaluate the effect of vvDD on cell viability. The data indicated that PD-L1 was highly expressed in CC tissues and cells following vvDD infection. MC38-luc cells were inoculated into mice to construct CC-bearing mouse models, which were treated with vvDD or combined with anti-PD-L1, with tumor growth, metastasis, survival, and the immune environment analyzed. It was found that OVV combined with anti-PD-L1 antibody led to lower tumor burden and growth and higher survival rates than individual treatment in CC-bearing mice. In addition, this combination exerted a remote effect on the untreated subcutaneous tumors in the lateral abdomen, thus suppressing the tumor metastasis. Furthermore, combined therapy of OVV with anti-PD-L1 antibody activated CD8+ T cells, reduced exhaustion of CD8+ T cells, and enhanced their immune response, strengthening the killing of CC cells and inhibiting tumor growth and metastasis. In conclusion, our findings provide mechanistic insights into the action and efficacy of OVV as an immunomodulatory agent combined with the anti-PD-L1 antibody for the treatment of CC.

Concurrent expression of HP-NAP enhances antitumor efficacy of oncolytic vaccinia virus but not for Semliki Forest virus

Oncolytic viruses (OVs) represent promising therapeutic agents for cancer therapy by selective oncolysis and induction of anti-tumor immunity. OVs can be engineered to express tumor-associated antigens and immune-modulating agents to provoke stronger antitumor immunity. Here, we engineered vaccinia virus (VV) and Semliki Forest virus (SFV) to express neuroblastoma-associated antigen disialoganglioside (GD2) and the immune modulator Helicobacter pylori neutrophil-activating protein (NAP) and compared their therapeutic potency. Oncolytic VV did not exhibit any antitumor benefits, whereas SFV was able to delay subcutaneous neuroblastoma (NXS2) tumor growth. Additional expression of the GD2 mimotope (GD2m) by VV-GD2m or SFV-GD2m did not improve their anti-tumor capacity compared to the parent viruses. Further arming these OVs with NAP resulted in contrasting anti-tumor efficacy. VV (VV-GD2m-NAP) significantly improved therapeutic efficacy compared to VV-GD2m, which was also associated with a significantly elevated anti-GD2 antibody, whereas there was no additive antitumor efficacy for SFV-GD2m-NAP compared to SFV-GD2m, nor was the anti-GD2 antibody response improved. Instead, NAP induced higher neutralizing antibodies against SFV. These observations suggest that distinct immune stimulation profiles are elicited when the same immunostimulatory factor is expressed by different OVs. Therefore, careful consideration and detailed characterization are needed when engineering OVs with immune-modulators.

Luteolin enhances the antitumor efficacy of oncolytic vaccinia virus that harbors IL-24 gene in liver cancer cells.

BackgroundInterleukin 24 (IL‐24) is an IL‐10 family member and a secreted cytokine characterized by cancer‐targeted toxicity and can activate apoptosis by sensitizing cancer cells to chemotherapy. Cytotoxic effects of luteolin on different types of cancer cells suppress their growth by acting on the components of the apoptosis signaling cascade. Therefore, our study aimed to prove whether oncolytic vaccinia virus (VV) that harbors IL‐24 (VV‐IL‐24) combine with luteolin exerts a synergistic inhibitory effect in liver cancer cells.MethodsImpacts on cell viability of VV‐IL‐24 and luteolin were assessed by MTT in various liver cancer cell lines. Then, liver cancer cell apoptosis was analyzed via flow cytometry and Western blotting. Besides, the MHCC97‐H xenograft mouse model was employed as a means of assessing in vivo antitumor efficacy.ResultsMTT assay confirmed that the combination treatment decreased liver cancer cells viability to a greater degree than treatment with VV‐IL‐24 or luteolin alone. Flow cytometry and Western blot assay proved that VV‐IL‐24 plus luteolin induced more liver cancer cells apoptosis than single treatment. Furthermore, in the MHCC97‐H xenograft model, 15 days of treatment with VV‐IL‐24 plus luteolin inhibited tumor growth significantly more than single treatment.ConclusionThese data confirm that the synergistic mechanism of VV‐IL‐24 and luteolin elicits a stronger tumor growth inhibition than any single therapy. Thus, the combination of VV‐IL‐24 and luteolin could provide the basis for preclinical research in the treatment of liver cancer.

Enhancing therapeutic efficacy of oncolytic vaccinia virus armed with Beclin-1, an autophagic Gene in leukemia and myeloma

Different strategies were taken to make virotherapy more effective at killing cancer cells. Among them, oncolytic virus which arms the therapeutic gene to enhance antitumor activity is a prevalent approach. In this study, a newly developed oncolytic vaccinia virus (OVV) that expresses Beclin-1 (OVV-BECN1) was tested for its in vitro and in vivo oncolytic activity in blood cancer. Results showed that the OVV exhibited higher infectivity for leukemia cells. OVV-BECN1 induced significant apoptosis-independent cell death either in wild-type leukemia and multiple myeloma (MM) cell lines or caspase-3 shRNA leukemia cell lines, and had a superior antitumor activity compared to the parent OVV. Autophagic cell death induced by OVV-BECN1 was demonstrated in vitro and in vivo experiments. Finally, upregulation of SIRT-1, a member of class III histone deacetylases, by OVV-BECN1 resulted in the deacetylation of LC3 and its distribution from the nucleus toward the cytoplasm, which might contribute to induction of autophagy. Overall, our data showed a favorable therapeutic effect of the oncolytic vaccinia virus on blood cancers through oncolytic and autophagic mechanisms, and may therefore constitute a promising and effective therapeutic strategy for treating human leukemia and MM. However, further studies are warranted for its reliable clinical translation.

Abstract LB-206: The synergistic antitumor effect of the combination of three transgenes delivered by the oncolytic vaccinia virus, KLS-3020

Abstract Oncolytic viruses that selectively kill cancer cells are a promising platform for fighting cancer. Vaccinia virus is a good candidate for the oncolytic virus because it has several advantages such as a proven safety profile, broad host tropism, and larger capacity to harbor multiple transgenes. We removed three viral genes (C11R, K3L, and J2R) from wild-type vaccinia virus to obtain a backbone virus, which is selectively replicating in cancer cells. Then, we inserted three transgenes (PH20, sPD1-Fc, and IL-12) into the backbone virus to boost up the antitumor efficacy, which is the final construct named KLS-3020. We investigated the biological activity of transgenes with the intratumorally injected backbone viruses containing each single transgene in syngeneic mouse tumor models. At first, the backbone virus expressing PH20, an enzyme which can degrade the tumor extracellular matrix, showed enhanced virus spread compared to the empty backbone virus in melanoma or colon cancer. Likewise, locally expressed sPD1-Fc, which is a fusion protein of the extracellular domain of PD-1 and Fc region of an immunoglobulin, resulted in the increase of INF-γ+CD8+ and INF-γ+CD4+ T cells in melanoma, indicating T cell re-activation in the tumor site. Lastly, delivered IL-12 in lung cancer mouse model resulted in a significant increase of T-bet+CD4+ T cell populations, indicating the oriented differentiation of helper T cell into T helper 1 (Th1) cells. We compared the efficacy of oncolytic vaccinia virus containing a combination of three transgenes (KLS-3020) with ones expressing each single gene in syngeneic mouse tumor models and observed that KLS-3020 could control tumor growth more effectively than every backbone virus having a single gene. Finally, we evaluated the anti-tumor efficacy of KLS-3020 in various types of mouse tumor models. Intratumorally injected KLS-3020 could suppress the growth of various tumors without significant body weight loss. Our results suggest that enhanced virus spread combined with the immune-stimulatory activity of KLS-3020 synergistically increase antitumor efficacy in a broad range of tumor types. Citation Format: Jaeil Shin, Soon-Oh Hong, Minjung Kim, Heonsik Choi, Sujeong Kim. The synergistic antitumor effect of the combination of three transgenes delivered by the oncolytic vaccinia virus, KLS-3020 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-206.

New role of Interleukin-10 in enhancing the antitumor efficacy of oncolytic vaccinia virus for treatment of pancreatic cancer

Although the profile of safety of tumor-targeted oncolytic virus (TOV) is encouraging, the antitumor efficacy of TOV alone is disappointing. Interleukin-10 (IL-10) plays an important role in carcinogenesis and anti-virus immunity. Here we report that tumor-targeted oncolytic vaccinia virus (VV) armed with IL10 shows promising potential for treatment of pancreatic cancer (PaCa).

Photodynamic therapy augments the efficacy of oncolytic vaccinia virus against primary and metastatic tumours in mice

Background:Therapies targeted towards the tumour vasculature can be exploited for the purpose of improving the systemic delivery of oncolytic viruses to tumours. Photodynamic therapy (PDT) is a clinically approved treatment for cancer that is known to induce potent effects on tumour vasculature. In this study, we examined the activity of PDT in combination with oncolytic vaccinia virus (OVV) against primary and metastatic tumours in mice.Methods:The effect of 2-[1-hexyloxyethyl-]-2-devinyl pyropheophorbide-a (HPPH)-sensitised-PDT on the efficacy of oncolytic virotherapy was investigated against subcutaneously implanted syngeneic murine NXS2 neuroblastoma and human FaDu head and neck squamous cell carcinoma xenografts in nude mice. Treatment efficacy was evaluated by monitoring tumour growth and survival. The effects of combination treatment on vascular function were examined using magnetic resonance imaging (MRI) and immunohistochemistry, whereas viral replication in tumour cells was analysed by a standard plaque assay. Normal tissue phototoxicity following PDT-OV treatment was studied using the mouse foot response assay.Results:Combination of PDT with OVV resulted in inhibition of primary and metastatic tumour growth compared with either monotherapy. PDT-induced vascular disruption resulted in higher intratumoural viral titres compared with the untreated tumours. Five days after delivery of OVV, there was a loss of blood flow to the interior of tumour that was associated with infiltration of neutrophils. Administration of OVV did not result in any additional photodynamic damage to normal mouse foot tissue.Conclusion:These results provide evidence into the usefulness of PDT as a means of enhancing intratumoural replication and therapeutic efficacy of OV.

A new recombinant vaccinia with targeted deletion of three viral genes: its safety and efficacy as an oncolytic virus

To enhance further the safety and efficacy of oncolytic vaccinia virus, we have developed a new virus with targeted deletions of three viral genes encoding thymidine kinase and antiapoptotic/host range proteins SPI-1 and SPI-2 (vSPT). Infection of human and murine tumor cell lines yielded nearly equivalent or a log lower virus recovery in comparison to parental viruses. Viral infection activated multiple caspases in cancer cells but not in normal cells, suggesting infected cells may die via different pathways. In tumor-bearing mice, vSPT recovery from MC38 tumor was slightly reduced in comparison to two parental viruses. However, no virus was recovered from the brains and livers of mice injected with vSPT in contrast to control viruses. vSPT demonstrated significantly lower pathogenicity in nude mice. Systemic delivery of vSPT showed significant tumor inhibition in subcutaneous MC38 tumor, human ovarian A2780 and murine ovarian MOSEC carcinomatosis models; however, the tumor inhibition by vSPT was reduced compared with parental viruses. These results demonstrated that although deletion of these three viral genes further enhanced tumor selectivity, it also weakened the oncolytic potency. This study illustrates the complexity of creating a tumor-selective oncolytic virus by deleting multiple viral genes involved in multiple cellular pathways.