Systemic Injection of Oncolytic Vaccinia Virus Suppresses Primary Tumor Growth and Lung Metastasis in Metastatic Renal Cell Carcinoma by Remodeling Tumor Microenvironment

Synergistic anti-tumor effects of oncolytic virus and anti-programmed cell death protein 1 antibody combination therapy: For suppression of lymph node and distant metastasis in a murine melanoma model

It is believed that oncolytic viruses (OVs) exert both direct anti-tumor effects by intratumoral injection as well as indirect anti-tumor effects by activating systemic immunity. In phase III clinical trials, OV and anti-programmed cell death-1 (aPD-1) antibody combination therapy showed no significant differences in overall survival and progression-free survival in patients with unresectable advanced melanoma. In the study, OVs can exert only indirect anti-tumor effects in non-injected, systemic lesions. If the tumor is at a stage where both direct and indirect anti-tumor effects of OVs can be expected, OVs may further enhance the therapeutic effect, in addition to the clinically expected therapeutic effect. Therefore, we investigated whether canerpaturev (C-REV) and aPD-1 antibody combination therapy suppresses tumor progression in a murine melanoma model. Our findings showed that the C-REV and aPD-1 antibody combination therapy suppressed tumor progression in a murine melanoma model. The combination therapy stimulated systemic immunity in lymphoid tissues by activating helper T cells and B cells to enhance adaptive and humoral immunity, as well as by increasing effector/memory T cell fractions. Synergistically enhanced systemic anti-tumor effects suppressed lymph node and lung metastases. These findings suggest that direct anti-tumor effects by infecting and destroying cancer cells from within and indirect anti-tumor effects enhanced by the combination therapy worked simultaneously to suppress tumor progression. Our results may provide evidence to support the usefulness of OV and aPD-1 antibody combination therapy as a neoadjuvant therapy in the surgical treatment of melanoma.

Innovative strategies in genitourinary cancer: the role of oncolytic viruses

Urinary tumors pose a significant health threat because of their high prevalence and recurrence rates. Despite the availability of various treatment options, many patients poorly respond to traditional therapies, highlighting the urgent need for alternative approaches. Oncolytic viruses are promising therapeutic agents. These viruses exploit the unique characteristics of cancer cells to specifically target and destroy them, thereby triggering potent antitumor immune responses. This review delves into recent advancements and future prospects of oncolytic viruses, focusing on their application in renal, bladder, and prostate cancers. By discussing practical implications and the potential of different viruses, including the cowpox virus, adenovirus, measles virus, coxsackievirus, and reovirus, we pave the way for further exploration and refinement of this exciting field.

Intratumoral Delivery of Interleukin 9 via Oncolytic Vaccinia Virus Elicits Potent Antitumor Effects in Tumor Models

The success of cancer immunotherapy is largely associated with immunologically hot tumors. Approaches that promote the infiltration of immune cells into tumor beds are urgently needed to transform cold tumors into hot tumors. Oncolytic viruses can transform the tumor microenvironment (TME), resulting in immunologically hot tumors. Cytokines are good candidates for arming oncolytic viruses to enhance their function in this transformation. Here, we used the oncolytic vaccinia virus (oVV) to deliver interleukin-9 (IL-9) into the tumor bed and explored its antitumor effects in colon and lung tumor models. Our data show that IL-9 prolongs viral persistence, which is probably mediated by the up-regulation of IL-10. The vvDD-IL-9 treatment elevated the expression of Th1 chemokines and antitumor factors such as IFN-γ, granzyme B, and perforin. IL-9 expression increased the percentages of CD4+ and CD8+ T cells in the TME and decreased the percentage of oVV-induced immune suppressive myeloid-derived suppressor cells (MDSC), leading to potent antitumor effects compared with parental virus treatment. The vvDD-IL-9 treatment also increased the percentage of regulatory T cells (Tregs) in the TME and elevated the expression of immune checkpoint molecules such as PD-1, PD-L1, and CTLA-4, but not GITR. The combination therapy of vvDD-IL-9 and the anti-CTLA-4 antibody, but not the anti-GITR antibody, induced systemic tumor-specific antitumor immunity and significantly extended the overall survival of mice, indicating a potential translation of the IL-9-expressing oncolytic virus into a clinical trial to enhance the antitumor effects elicited by an immune checkpoint blockade for cancer immunotherapy.

PD-1 inhibitor plus oncolytic vaccinia virus is a safe and effective treatment option for metastatic renal cell carcinoma

BACKGROUND

Although a combination of immune checkpoint inhibitors (ICIs) is recommended as the first line treatment option for metastatic renal cell carcinoma (mRCC), several immune-related adverse events (irAEs) occur, especially hepatitis. We explored the therapeutic benefits and safety profile of combining oncolytic vaccinia virus, JX-594, with a programmed cell death protein-1 (PD-1) inhibitor.

METHODS

We used early-stage and advanced-stage orthotopic murine mRCC models developed by our group. PD-1 inhibitor monotherapy or a PD-1 inhibitor combined with either JX-594 or a cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) inhibitor were systemically injected through the peritoneum. An immunofluorescence analysis was performed to analyze the tumor immune microenvironment (TIME). irAEs were assessed in terms of hepatitis.

RESULTS

In the early-stage mRCC model mice, the combination of JX-594 and a PD-1 inhibitor significantly decreased the primary tumor size and number of lung nodules, compared with the ICI combination, but the JX-594 and PD-1 inhibitor combination and ICI combination did not differ significantly in the advanced-stage mRCC model mice. The JX-594 and PD-1 inhibitor combination induced tumor-suppressing TIME changes in both the early- and advanced-stage mRCC models. Furthermore, mice treated with the ICI combination had significantly greater hepatic injuries than those treated with the JX-594 and PD-1 inhibitor combination which was evaluated in early-stage mRCC model.

CONCLUSIONS

The JX-594 and PD-1 inhibitor combination effectively reduced primary tumors and the metastatic burden, similar to ICI combination therapy, through dynamic remodeling of the TIME. Furthermore, hepatitis was significantly decreased in the JX-594 and PD-1 inhibitor combination group, suggesting the potential benefit of that combination for reducing ICI-induced toxicity.

Generation of novel oncolytic vaccinia virus with improved intravenous efficacy through protection against complement-mediated lysis and evasion of neutralization by vaccinia virus-specific antibodies

BACKGROUND

Oncolytic virus immunotherapy has revolutionized cancer immunotherapy by efficiently inducing both oncolysis and systemic immune activation. Locoregional administration has been used for oncolytic virus therapy, but its applications to deep-seated cancers have been limited. Although systemic delivery of the oncolytic virus would maximize viral immunotherapy's potential, this remains a hurdle due to the rapid removal of the administered virus by the complement and innate immune system. Infected cells produce some vaccinia viruses as extracellular enveloped virions, which evade complement attack and achieve longer survival by expressing host complement regulatory proteins (CRPs) on the host-derived envelope. Here, we generated SJ-600 series oncolytic vaccinia viruses that can mimic complement-resistant extracellular enveloped virions by incorporating human CRP CD55 on the intracellular mature virion (IMV) membrane.

METHODS

The N-terminus of the human CD55 protein was fused to the transmembrane domains of the six type I membrane proteins of the IMV; the resulting recombinant viruses were named SJ-600 series viruses. The SJ-600 series viruses also expressed human granulocyte-macrophage colony-stimulating factor (GM-CSF) to activate dendritic cells. The viral thymidine kinase (J2R) gene was replaced by genes encoding the CD55 fusion proteins and GM-CSF.

RESULTS

SJ-600 series viruses expressing human CD55 on the IMV membrane showed resistance to serum virus neutralization. SJ-607 virus, which showed the highest CD55 expression and the highest resistance to serum complement-mediated lysis, exhibited superior anticancer activity in three human cancer xenograft models, compared with the control Pexa-Vec (JX-594) virus, after single-dose intravenous administration. The SJ-607 virus administration elicited neutralizing antibody formation in two immunocompetent mouse strains like the control JX-594 virus. Remarkably, we found that the SJ-607 virus evades neutralization by vaccinia virus-specific antibodies.

CONCLUSION

Our new oncolytic vaccinia virus platform, which expresses human CD55 protein on its membrane, prolonged viral survival by protecting against complement-mediated lysis and by evading neutralization by vaccinia virus-specific antibodies; this may provide a continuous antitumor efficacy until a complete remission has been achieved. Such a platform may expand the target cancer profile to include deep-seated cancers and widespread metastatic cancers.

Ferroptosis Inducer Improves the Efficacy of Oncolytic Virus-Mediated Cancer Immunotherapy

Ferroptosis is a type of programmed cell death dependent on iron and characterized by the accumulation of lipid peroxides. In this study, we explore the combination of a ferroptosis activator with an oncolytic vaccinia virus in tumor models. Erastin induced cell death in hepatoma, colon, and ovarian cancer cells, but not in melanoma cancer cells. Erastin, not the oncolytic vaccinia virus (OVV), induced the expression of key marker genes for ferroptosis in cancer cells. In hepatocellular carcinoma and colon cancer models, either erastin or OVV inhibited tumor growth, but a combination of the two yielded the best therapeutic effects, as indicated by inhibited tumor growth or regression and longer host survival. Immunological analyses indicate that erastin alone had little or no effect on systemic immunity or local immunity in the tumor. However, when combined with OV, erastin enhanced the number of activated dendritic cells and the activity of tumor-infiltrating T lymphocytes as indicated by an increase in IFN-γ+CD8+ and PD-1+CD8+ T cells. These results demonstrate that erastin can exert cytotoxicity on cancer cells via ferroptosis, but has little effect on immune activity by itself. However, when combined with an OVV, erastin promoted antitumoral immunity and efficacy by increasing the number of activated dendritic cells and promoting the activities of tumor specific CD8+ T cells in the tumor.

Oncolytic Vaccinia Virus Augments T Cell Factor 1-Positive Stem-like CD8+ T Cells, Which Underlies the Efficacy of Anti-PD-1 Combination Immunotherapy

Oncolytic virotherapy has garnered attention as an antigen-agnostic therapeutic cancer vaccine that induces cancer-specific T cell responses without additional antigen loading. As anticancer immune responses are compromised by a lack of antigenicity and chronic immunosuppressive microenvironments, an effective immuno-oncology modality that converts cold tumors into hot tumors is crucial. To evaluate the immune-activating characteristics of oncolytic vaccinia virus (VACV; JX-594, pexastimogene devacirepvec), diverse murine syngeneic cancer models with different tissue types and immune microenvironments were used. Intratumorally administered mJX-594, a murine variant of JX-594, potently increased CD8+ T cells, including antigen-specific cancer CD8+ T cells, and decreased immunosuppressive cells irrespective of tissue type or therapeutic efficacy. Remodeling of tumors into inflamed ones by mJX-594 led to a response to combined anti-PD-1 treatment, but not to mJX-594 or anti-PD-1 monotherapy. mJX-594 treatment increased T cell factor 1-positive stem-like T cells among cancer-specific CD8+ T cells, and anti-PD-1 combination treatment further increased proliferation of these cells, which was important for therapeutic efficacy. The presence of functional cancer-specific CD8+ T cells in the spleen and bone marrow for an extended period, which proliferated upon encountering cancer antigen-loaded splenic dendritic cells, further indicated that long-term durable anticancer immunity was elicited by oncolytic VACV.