Hydrogel reservoir unlocks potential for HSV-1 viral therapy in cancer

In a recent study published in communication biologyResearchers evaluated the therapeutic effects of naboximod in combination with herpes simplex 1 (HSV-1) viral therapy for hepatocellular carcinoma (HCC).

study: Naboximod modulates local HSV-1 replication to reshape the tumor immune microenvironment and enhance injectable hydrogel immunotherapy. Image credit: PaeGAG/Shutterstock.com

Background

Cancer immunotherapy has achieved great success in the treatment of various cancers.But HCC is threatening efficacy of Immunotherapy is due to poor response rates and adverse outcomes due to the complex and potent immunosuppressive tumor microenvironment (TME). Therefore, new strategies are needed to improve HCC outcomes.

Oncolytic virus therapy destroys tumor cells and generates a systemic anti-tumor immune response. However, it has limited efficacy in humans due to impaired viral replication and inability to overcome TME.

Optimizing viral-based therapies requires carefully modulating and balancing anti-tumor immunological activation and anti-viral immunological suppression.

The indoleamine 2,3-dioxygenase 1 (IDO1) protein is an important immunosuppressive molecule reported to be upregulated in multiple tumors. IDOI inhibits cytotoxicity [natural killer (NK) and cluster of differentiation 8-expressing (CD8+)] T cells and lymphocytes, improving regulatory function T cells It promotes the recruitment of myeloid-derived suppressor cells (MDSCs) by promoting the conversion of tryptophan to kynurenine. Studies report her IDO1 inhibitors as an effective option for immunotherapy.

About research

This study investigated whether naboximod, an indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor, can promote HSV-1-based therapy and improve HCC outcomes.

The research team loaded naboximod and HSV-1 into an injectable biocompatible hydrogel for local-level drug delivery and maximized viral distribution to HCC for virotherapy. They performed single-cell ribonucleic acid sequencing (scRNA-seq) to assess the immunological profile of tumor sites.

This study then investigated interferon-stimulated genes (ISGs) that inhibit HSV-1 proliferation to optimize HSV-1-based oncolytic immunotherapy.

A green fluorescent protein (GFP) signal generated from GFP-tagged HSV-1 was also used to assess HSV-1 proliferation. In addition, quantitative polymerase chain reaction (qPCR) and western blot analysis were performed to assess her IDO1 levels in her Hepa1-6 cells after HSV-1 treatment.

The effect of naboximod on HSV-1 proliferation was studied in SMMC-7721 (human hepatocellular carcinoma) cells, 4T1 (mouse mammary carcinoma) cells, and live Using the rabbit VX-2 liver cancer model.

Silk hydrogels were generated from cocoons to deliver oncolytic viruses. Scanning electron microscopy (SEM) and confocal microscopy (CFM) were performed to assess hydrogel porosity and virion distribution.

The research team measured HSV-1 deoxyribonucleic acid (DNA) levels in nervous system, blood, and peripherally located organs after subcutaneous injection of hydrogels to assess their cytotoxicity.

To assess cytolytic damage to tumor tissue, we stained tumor sections using hematoxylin and eosin (H&E), TUNEL, and Ki67 stains. To confirm systemic changes in TME, we performed flow cytometry (FC) analysis and immunohistochemistry (IHC) staining.

result

Based on the Cancer Genome Atlas (TCGA) dataset, RNA-seq results showed that IDO1 is overexpressed in HCC. Naboximod promotes HSV-1 proliferation and herpes simplex virus 1-induced oncolysis in tumor cells and may be an effective therapeutic option when combined with herpes simplex virus 1-based viral oncolytic therapy.

With a single injection, the hydrogel forms a local depot, maximizing viral propagation and spread at the tumor site.

Notably, hydrogels extended the disease-free lifespan of HCC mice, protected against tumor recurrence, and were effective in a rabbit orthotopic liver tumor model. Mechanistically, combining HSV-1 virotherapy with IDO1 inhibition completely reprogrammed the tumor microenvironment through scRNA sequencing.

The hydrogel acted as a reservoir for local delivery, allowing HSV-1 to maintain cytotoxic activity and spread to tumor sites while mitigating off-target damage to peripheral organs. This method produced a complete response to the treatment of HCC subcutaneous malignancies, whereas HSV-1 or HSV-1/naboximod mixtures not incorporated into hydrogels produced only modest responses.

This hydrogel can counter the immunosuppressive tumor microenvironment, primarily by modifying immune cell populations, including effector memory (EM) and accumulation of NKT lymphocytes. IDO1 upregulation inhibited HSV-1 proliferation, as shown by HSV DNA and gD envelope protein levels.

Results were consistently observed using 4T1 and SMMC-7721 cells. IDO1 was found to be overproduced in tumor tissues and further increased by herpes simplex virus 1 therapy, acting as a type of negative feedback to inhibit herpes simplex virus 1 proliferation in cancer cells.

Bone marrow-derived cells (M1 macrophages, monocytes, dendritic cells) and T/NK cells predominantly infiltrated the tumor site.

Reverse transcription-PCR shows that CC chemokine ligand 2 (CCL-2) and CXC motif ligand (CXCL)-10 and -11 genes are upregulated by hydrogel treatment, according to the results of gene ontology (GO) enrichment analysis. I was. IDO1 suppressed anti-tumor immunity, suggesting that her IDO1 should be blocked during herpes simplex virus type 1-based immunotherapy.

Hydrogels rapidly eradicated tumor recurrence by inducing the conversion of naive and central memory (CM) T lymphocytes to effector memory (EM) T lymphocytes. Given its efficacy, biological safety, and low systemic toxicity, it demonstrated promising potential as a delivery route for oncolytic viruses.

Conclusion

The study results showed that combining naboximod and HSV-1 can promote viral replication and reconstitute TME for tumor eradication via hydrogel reservoirs.

Naboximod enhanced the oncolytic and replicative effects of herpes simplex virus-1 in vitro and live Further investigation is needed to develop new strategies and reduce the global cancer burden.