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Updated: Aug 15, 2026
Paramyxoviruses for Tumor-targeted Immunomodulation: Design and Evaluation Ex Vivo
Published on: January 7, 2019
Enhanced therapeutic efficacy of IL-12, but not GM-CSF, expressing oncolytic herpes simplex virus for transgenic
S Varghese1, S D Rabkin, R Liu
1Department of Neurosurgery, Molecular Neurosurgery Laboratory, Massachusetts General Hospital, Charlestown, 02129, USA.
Abstract:
Replication competent oncolytic herpes simplex viruses (HSV) with broad-spectrum activity against various cancers, including prostate cancer, exert a dual effect by their direct cytocidal action and by eliciting tumor-specific immunity. These viruses can deliver immunoregulatory molecules to tumors so as to enhance the cumulative antitumor response. This is particularly desirable for prostate cancers, which are usually poorly immunogenic. Initial studies described herein comparing the efficacy of three different oncolytic HSVs (G207, G47Delta, and NV1023) to inhibit the growth of the poorly immunogenic TRAMP-C2 mouse prostate tumors demonstrated that NV1023 was most effective in treating established tumors. The expression of IL-12 on an NV1023 background (NV1042), but not the expression of GM-CSF (NV1034), further enhanced the efficacy of NV1023 in two murine prostate cancer models with highly variable MHC class I levels, Pr14-2 with 91% and TRAMP-C2 with 2% of cells staining. NV1042 also inhibited the growth of distant noninoculated tumors in both prostate cancer models. NV1042 treated tumors exhibited increased immune cell infiltration and decreased levels of angiogenesis. Thus, an IL-12 expressing oncolytic herpes virus, which is capable of direct cytotoxicity and can modulate the otherwise suboptimal immune response through concomitant expression of the cytokine at the site of tumor destruction, could serve as a valuable clinical agent to seek out both overt and occult prostate cancers.
Insights
Oncolytic herpes simplex viruses (HSV) expressing IL-12 show enhanced efficacy against prostate cancer by directly killing tumors and stimulating immunity. This approach targets both visible and hidden tumors, offering a promising new therapy.
Area of Science:
- Oncolytic virotherapy
- Cancer immunology
- Prostate cancer research
Background:
- Replication-competent oncolytic herpes simplex viruses (HSV) offer dual action: direct tumor cell killing and eliciting tumor-specific immunity.
- Prostate cancer is often poorly immunogenic, necessitating strategies to enhance anti-tumor immune responses.
- Oncolytic viruses can be engineered to deliver immunomodulatory molecules, boosting therapeutic outcomes.
Purpose of the Study:
- To compare the efficacy of three oncolytic HSV candidates (G207, G47Delta, NV1023) against a poorly immunogenic mouse prostate tumor model.
- To evaluate the impact of expressing interleukin-12 (IL-12) or granulocyte-macrophage colony-stimulating factor (GM-CSF) on an enhanced oncolytic HSV (NV1023) in prostate cancer.
- To assess the ability of the engineered oncolytic virus to inhibit distant, non-injected tumors and modulate the tumor microenvironment.
Main Methods:
- Comparative efficacy study of three oncolytic HSV vectors (G207, G47Delta, NV1023) in TRAMP-C2 mouse prostate tumor models.
- Generation and testing of NV1023 engineered to express IL-12 (NV1042) or GM-CSF (NV1034).
- Assessment of tumor growth inhibition, immune cell infiltration, angiogenesis, and distant tumor control in murine prostate cancer models with variable MHC class I expression.
Main Results:
- NV1023 demonstrated superior efficacy in inhibiting established TRAMP-C2 prostate tumors compared to G207 and G47Delta.
- NV1042 (NV1023 expressing IL-12) significantly enhanced anti-tumor efficacy in two distinct murine prostate cancer models, whereas NV1034 (expressing GM-CSF) did not.
- NV1042 inhibited distant, non-injected tumors and led to increased immune cell infiltration and reduced angiogenesis within treated tumors.
Conclusions:
- Engineered oncolytic herpes simplex virus expressing IL-12 (NV1042) is a potent therapeutic agent for prostate cancer.
- NV1042 combines direct oncolysis with enhanced, localized immune stimulation, effectively targeting both primary and distant tumors.
- This IL-12 expressing oncolytic virus holds promise for treating both overt and occult prostate cancers by overcoming tumor-induced immune suppression.
