Evaluation of the oncolytic potential of R2B Mukteshwar vaccine strain of Newcastle disease virus (NDV) in a colon cancer cell line (SW-620). Arch Virol. 2017;162:2705-2713. [PMID: 28578522 DOI: 10.1007/s00705-017-3411-4]

Intestinal Microbiota Modulates the Antitumor Effect of Oncolytic Virus Vaccines in Colorectal Cancer

BACKGROUND

Immunotherapies, such as oncolytic viruses, have become powerful cancer treatments, but only some patients with cancer can benefit from them, especially those with advanced-stage cancer, and new therapeutic strategies are needed to facilitate extended survival. The intestinal microbiota may contribute to colorectal cancer (CRC) carcinogenesis and the response to immunotherapy. However, whether and how the intestinal microbiota modulates the effects of oncolytic virus vaccines (OVVs) in CRC remain to be investigated.

METHODS

We generated an MC38-gp33 CRC mouse model and treated it with OVV-gp33 in early and advanced stages. Probiotics, fecal microbiota transplantation (FMT), and antibiotics (ABX) were administered to regulate the microbial composition of CRC mice at an advanced stage. The tumor growth rate and survival time of the mice were recorded; 16S rDNA sequencing was used to analyze the microbial composition and flow cytometry was used to detect T-cell subset activity.

RESULTS

OVV-gp33 treatment inhibited tumor growth and prolonged survival in the early stage of CRC but did not have a significant effect on the advanced stage of CRC. Moreover, 16S rDNA sequence analysis and flow cytometry showed significant differences in intestinal microbiota composition, microbial metabolites, and T-cell subsets in early and advanced-stage CRC. Probiotic and FMT treatment significantly enhanced the antitumor effect of OVV in the advanced stage of CRC with an increased abundance of activated CD8+ T cells and a decreased ratio of Treg cells, while depletion of the microbiota by ABX eliminated the antitumor activity of OVV with decreased CD8+ T-cell activation and upregulated Treg cells.

CONCLUSIONS

These results indicate that the intestinal microbiota and microbial metabolites play an important role in the antitumor effect of OVV in CRC. Furthermore, altering the intestinal microbiota composition can modulate the antitumor and immunomodulatory effects of OVV in CRC.

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.

Evaluation of the oncolytic property of recombinant Newcastle disease virus strain R2B in 4T1 and B16-F10 cells in-vitro

Recombinant Newcastle disease virus vectors have gained a lot of interest for its oncolytic virus therapy and cancer immune therapeutic properties due to its selective replication to high titers in cancer cells. The aim of this study was to find out the oncolytic effects of mesogenic recombinant NDV strain R2B-GFP on murine mammary tumor cell line 4T1 and murine melanoma cell line B16-F10. The anti-tumor effects of R2B-GFP virus were studied via expression of virus transgene GFP in cancer cells, evaluating its cytotoxicity and cell migration efficacies by MTT and wound healing assays respectively. In addition, the underlying apoptotic mechanism of R2B-GFP virus was estimated by TUNEL assay, colorimetric estimation of Caspase-3, 8 and 9 and the estimation of Bax to Bcl-2 ratio. The results showed a significant decrease in viability of both 4T1 and B16-F10 cells infected with R2B-GFP virus at 0.1 and 1 MOI. R2B-GFP virus could significantly induce apoptosis in the 4T1 and B16-F10 cells as compared to the uninfected control. Further, a flow cytometry analysis on apoptotic cells percentage and mitochondria membrane permeability test was also studied in R2B-GFP virus treated 4T1 and B16-F10 cell lines. The R2B-GFP virus caused an increase in loss of mitochondrial membrane permeability in both 4T1 and B16-F10 cells indicating the involvement of mitochondrial regulated cell death. Thus, the recombinant virus R2B-GFP virus proved to be a valid candidate for oncolytic viral therapy in 4T1 and B16-F10 cells.

T-cell-based immunotherapy in colorectal cancer

Colorectal cancer (CRC) is the leading cause of cancer death worldwide. CRC therapeutic strategies include surgical resection, chemotherapy, radiotherapy, and other approaches. However, patients with metastatic CRC have worse prognoses. In recent years, T-cell-based immunotherapy has elicited promising responses in B-cell malignancies, melanoma, and lung cancer, but most CRC patients are resistant to immunotherapy, chemotherapy, and targeted therapy. Immune checkpoint inhibitors have shown encouraging results in non-small cell lung cancer, melanoma, and other cancers, but immune checkpoint blockade is only effective for CRC subset with microsatellite instability. Other immunotherapies, such as cytokines, cancer vaccines, small molecules, oncolytic viruses, and chimeric antigen-receptor therapy, are currently in use against CRC. This review analyzes recent developments in immunotherapy for CRC treatment as well as the challenges in overcoming resistance.

Immunotherapeutic Approaches for the Treatment of Colorectal Cancer

Colorectal cancer (CRC) originating from the cells of the colon or rectum has a high mortality rate worldwide. Numerous attempts have been made to raise the overall survival rates of CRC patients. It is well-known that the development of malignant neoplasms is accompanied by suppression of the immune system, which is likely the cause for the failure of standard treatment methods. Immune response has long been an issue of great interest in cancer therapy and anti-tumor immunity that consider the development of immunotherapeutic antitumor methods resulting in the immune system activation as an important issue. This review discusses main immunotherapeutic approaches available for the CRC treatment.

Breaking Therapy Resistance: An Update on Oncolytic Newcastle Disease Virus for Improvements of Cancer Therapy

Resistance to therapy is a major obstacle to cancer treatment. It may exist from the beginning, or it may develop during therapy. The review focusses on oncolytic Newcastle disease virus (NDV) as a biological agent with potential to break therapy resistance. This avian virus combines, upon inoculation into non-permissive hosts such as human, 12 described anti-neoplastic effects with 11 described immune stimulatory properties. Fifty years of clinical application of NDV give witness to the high safety profile of this biological agent. In 2015, an important milestone was achieved, namely the successful production of NDV according to Good Manufacturing Practice (GMP). Based on this, IOZK in Cologne, Germany, obtained a GMP certificate for the production of a dendritic cell vaccine loaded with tumor antigens from a lysate of patient-derived tumor cells together with immunological danger signals from NDV for intracutaneous application. This update includes single case reports and retrospective analyses from patients treated at IOZK. The review also presents future perspectives, including the concept of in situ vaccination and the combination of NDV or other oncolytic viruses with checkpoint inhibitors.

Application of Newcastle disease virus in the treatment of colorectal cancer

Colorectal cancer (CRC) is one of the main reasons of tumor-related deaths worldwide. At present, the main treatment is surgery, but the results are unsatisfactory, and the prognosis is poor. The majority of patients die due to liver or lung metastasis or recurrence. In recent years, great progress has been made in the field of tumor gene therapy, providing a new treatment for combating CRC. As oncolytic viruses selectively replicate almost exclusively in the cytoplasm of tumor cells and do not require integration into the host genome, they are safer, more effective and more attractive as oncolytic agents. Newcastle disease virus (NDV) is a natural RNA oncolytic virus. After NDV selectively infects tumor cells, the immune response induced by NDV’s envelope protein and intracellular factors can effectively kill the tumor without affecting normal cells. Reverse genetic techniques make NDV a vector for gene therapy. Arming the virus by inserting various exogenous genes or using NDV in combination with immunotherapy can also improve the anti-CRC capacity of NDV, and good results have been achieved in animal models and clinical treatment trials. This article reviews the molecular biological characteristics and oncolytic mechanism of NDV and discusses in vitro and in vivo experiments on NDV anti-CRC capacity and clinical treatment. In conclusion, NDV is an excellent candidate for cancer treatment, but more preclinical studies and clinical trials are needed to ensure its safety and efficacy.