What question did this study set out to answer?

The aim is to investigate the effects of co-expressing FIH1 and IL-12 in oncolytic HSV-1 on Notch signaling and anti-tumor immunity in glioblastoma.

April 4, 2026

Abstract 355: Co-expression of FIH1 and IL-12 in oncolytic HSV-1 blocks Notch signaling and enhances anti-tumor immunity.

Key Points

The aim is to investigate the effects of co-expressing FIH1 and IL-12 in oncolytic HSV-1 on Notch signaling and anti-tumor immunity in glioblastoma.
Developed oncolytic herpes simplex virus expressing FIH1 and IL-12 for targeted therapy.
Conducted in vitro studies to assess Notch signaling downregulation.
Utilized in vivo mouse models to evaluate survival outcomes and tumor growth.
Performed single-cell RNA sequencing on treated tumors to analyze immune cell populations.
Notch signaling was significantly downregulated in treated glioblastoma cells.
Combination treatment showed delayed tumor growth and extended survival in mouse models.
Single-cell sequencing revealed reduced tumor-associated macrophages and an increased T cell population post-treatment.

Abstract

Abstract Glioblastoma (GBM) is the most aggressive brain tumor in adults and remains a lethal disease with limited treatment options despite continuing worldwide efforts to develop new therapies. GBM cells often exhibit increased Notch signaling, whose activity contributes to tumor progression and therapy resistance. Previous clinical trials aimed to target Notch signaling using ɣ-secretase inhibitors (GSIs) but have not been fully successful due off-target effects, dose-limiting toxicity and eventual resistance. Here, we have generated an oncolytic herpes simplex virus (oHSV) that expresses the asparaginyl hydroxylase factor inhibiting HIF (FIH1) which efficiently targets Notch signaling locally and specifically in GBM and other solid tumors. Using this virus, OncoD-F, we have shown successful downregulation of Notch signaling in vitro and significant survival improvement in in vivo mouse models of GBM. Furthermore, scRNA sequencing analysis of mouse brain tumors treated with OncoD-F have shown a reduction in tumor associated macrophages and an enrichment in the T cell population. Based on these observations, and in order to enhance the cytotoxic activity of the recruited T cells, we combined OncoD-F treatment with intratumoral injections of the immunoregulatory cytokine IL-12 in a subcutaneous tumor model. Mice receiving the combination treatment had a delayed tumor growth and had a longer time to reach endpoint. Given the favorable response of the combination treatment, we have expressed IL-12 in OncoD-F to generate OncoD-F12. The findings from this study suggest the potential of multi-modality therapeutic strategies for GBM and other solid tumors that have oncogenic Notch activation. Citation Format: Karina Vazquez-Arreguin, Balveen Kaur. Co-expression of FIH1 and IL-12 in oncolytic HSV-1 blocks Notch signaling and enhances anti-tumor immunity abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 355.

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