HOX and PBX gene dysregulation as a therapeutic target in glioblastoma multiforme

Background: Glioblastoma multiforme (GBM) is the most common high-grade malignant brain tumour in adults and arises from the glial cells in the brain. The prognosis of treated GBM remains very poor with 5-year survival rates of 5%, a figure which has not improved over the last few decades. Currently, there is a modest 14-month overall median survival in patients undergoing maximum safe resection plus adjuvant chemoradiotherapy. HOX gene dysregulation is now a widely recognised feature of many malignancies. Methods: In this study we have focused on HOX gene dysregulation in GBM as a potential therapeutic target in a disease with high unmet need. Results: We show significant dysregulation of these developmentally crucial genes and specifically that HOX genes A9, A10, C4 and D9 are strong candidates for biomarkers and treatment targets for GBM and GBM cancer stem cells. We evaluated a next generation therapeutic peptide, HTL-001, capable of targeting HOX gene over-expression in GBM by disrupting the interaction between HOX proteins and their co-factor, PBX. HTL-001 induced both caspase-dependent and -independent apoptosis in GBM cell lines. Conclusion: In vivo biodistribution studies confirmed that the peptide was able to cross the blood brain barrier. Systemic delivery of HTL-001 resulted in improved control of subcutaneous murine and human xenograft tumours and improved survival in a murine orthotopic model

A T-cell engager-armed oncolytic vaccinia virus to target the tumor stroma

Aim: Cancer-associated fibroblasts (CAFs) are the key cellular components of the tumor stroma. CAFs express fibroblast activation protein (FAP) and FAP-targeted immunotherapies have shown potent antitumor effects in preclinical mouse studies, highlighting their central role in tumorigenesis. However, safety concerns have been raised in regard to FAP-targeted immunotherapies since bone marrow failure and cachexia were observed in transgenic models and preclinical studies. Here, we describe a novel oncolytic virotherapy by locally targeting FAP within tumor tissue. Methods: T-cell engager-armed oncolytic vaccinia virus (TEA-VV) that encodes a secretory bi-specific T-cell engager consisting of two single-chain variable fragments specific for murine CD3 and fibroblast activation protein (mFAP-TEA-VV) was generated. The antitumor effects of mFAP-TEA-VV were compared to unmodified VVs using standard in vitro immunological assays and an immunocompetent B16 melanoma mouse model. Results: In vitro, the ability of mFAP-TEA-VV to replicate within tumor cells and induce oncolysis was similar to that of unmodified VVs. However, in co-culture assays, only mFAP-TEA-VV induced bystander killing of noninfected FAP-expressing cells in the presence of murine T-cells. In vivo, mFAP-TEA-VV enhanced viral titer within the tumor and had potent antitumor activity in comparison to control VVs in an immunocompetent B16 melanoma mouse model. Importantly, the improved viral spread of mFAP-TEA-VV correlated with the destruction of tumor stroma. Conclusion: Arming oncolytic VVs with an FAP-targeted T-cell engager may be a promising improvement to oncolytic virus therapy for solid tumors

Replication and Spread of Oncolytic Herpes Simplex Virus in Solid Tumors

Oncolytic herpes simplex virus (oHSV) is a highly promising treatment for solid tumors. Intense research and development efforts have led to first-in-class approval for an oHSV for melanoma, but barriers to this promising therapy still exist that limit efficacy. The process of infection, replication and transmission of oHSV in solid tumors is key to obtaining a good lytic destruction of infected cancer cells to kill tumor cells and release tumor antigens that can prime anti-tumor efficacy. Intracellular tumor cell signaling and tumor stromal cells present multiple barriers that resist oHSV activity. Here, we provide a review focused on oncolytic HSV and the essential viral genes that allow for virus replication and spread in order to gain insight into how manipulation of these pathways can be exploited to potentiate oHSV infection and replication among tumor cells

A20 controls macrophage to elicit potent cytotoxic CD4(+) T cell response.

Emerging evidence indicates that CD4(+) T cells possess cytotoxic potential for tumor eradication and perforin/granzyme-mediated cytotoxicity functions as one of the important mechanisms for CD4(+) T cell-triggered cell killing. However, the critical issue is how the cytotoxic CD4(+) T cells are developed. During the course of our work that aims at promoting immunostimulation of APCs by inhibition of negative regulators, we found that A20-silenced Mф drastically induced granzyme B expression in CD4(+) T cells. As a consequence, the granzyme-highly expressing CD4(+) T cells exhibited a strong cytotoxic activity that restricted tumor development. We found that A20-silenced Mф activated cytotoxic CD4(+) T cells by MHC class-II restricted mechanism and the activation was largely dependent on enhanced production of IFN-γ

A20-silenced Mф elicits a cytotoxic CD4⁺ T cell response via activation of IFN-γ signaling and by an MHC-class-II-restricted mechanism.

<p>A. Adenoviral-transduced BMMфs were used to immunize IFNGR^−/− mice or the wildtype littermates (2–3 mice/group) twice. The inguinal LNs were harvested for analyzing expression of granzyme B in CD4⁺ or CD8⁺ T cells by ICS. p<0.01 Ad-shA20-IFNGR KO mice vs. Ad-ShA20 WT mice. B. Adenoviral-transduced BMMфs were used to immunize Stat1^−/− mice or the wild-type littermates twice (2–3 mice/group). The LNs were harvested for analyzing expression of granzyme B in CD4⁺ (p<0.05, Ad-shA20-Stat1 KO mice vs. Ad-shA20-WT mice) or CD8⁺ T cells by ICS. C. BMMфs were prepared from MHCII^−/− mice or the wild-type littermates. The adenoviral-transduced BMMфs were used to immunize wild-type mice (2–3 mice/group) twice. The LNs were harvested for analyzing expression of granzyme B in CD4⁺ (p<0.01, Ad-shA20-MHC-II KO Mф immunization vs. Ad-shA20-WT Mф immunization) or CD8⁺ T cells by ICS. Experiments were repeated with similar results.</p

PKR induces TGF-β and limits oncolytic immune therapy

Background Mammalian cells have developed multiple intracellular mechanisms to defend against viral infections. These include RNA-activated protein kinase (PKR), cyclic GMP-AMP synthase and stimulation of interferon genes (cGAS-STING) and toll-like receptor-myeloid differentiation primary response 88 (TLR-MyD88). Among these, we identified that PKR presents the most formidable barrier to oncolytic herpes simplex virus (oHSV) replication in vitro.Methods To elucidate the impact of PKR on host responses to oncolytic therapy, we generated a novel oncolytic virus (oHSV-shPKR) which disables tumor intrinsic PKR signaling in infected tumor cells.Results As anticipated, oHSV-shPKR resulted in suppression of innate antiviral immunity and improves virus spread and tumor cell lysis both in vitro and in vivo. Single cell RNA sequencing combined with cell-cell communication analysis uncovered a strong correlation between PKR activation and transforming growth factor beta (TGF-ß) immune suppressive signaling in both human and preclinical models. Using a murine PKR targeting oHSV, we found that in immune-competent mice this virus could rewire the tumor immune microenvironment to increase the activation of antigen presentation and enhance tumor antigen-specific CD8 T cell expansion and activity. Further, a single intratumoral injection of oHSV-shPKR significantly improved the survival of mice bearing orthotopic glioblastoma. To our knowledge, this is the first report to identify dual and opposing roles of PKR wherein PKR activates antivirus innate immunity and induces TGF-ß signaling to inhibit antitumor adaptive immune responses.Conclusions Thus, PKR represents the Achilles heel of oHSV therapy, restricting both viral replication and antitumor immunity, and an oncolytic virus that can target this pathway significantly improves response to virotherapy

Neutralization of IFN-γ reduces A20-silenced MФ to prime cytotoxic T cell response <i>in vitro.</i>

<p>BMMфs were transduced with Ad-shA20 and cocultured with CD4⁺ OT-II (<b>A</b>) or CD8⁺ OT-I (<b>B</b>) T cells in the presence of the different doses of anti-IL-6, anti-IL-12 or anti-IFN-γ (2.5 ug/ml, 10 ug/ml, or 20 ug/ml ) for 3–5 days. Expression of granzyme B in T cells was assessed by ICS assay. The data is a representative of three independent experiments. p<0.01, OT-II/AdshA20-Mф vs. OT-II/AdshA20-Mф+anti-IFN-γ(20 ug/ml).</p

IFN-γ impacts MФ to trigger cytotoxic T cell responses in immunized mice.

<p>C57BL/6 mice (2–3 mice per group) were immunized twice with 1, PBS plus IgG; 2, PBS plus IFN-γ; 3, Ad-con-Mф; 4, Ad-con-Mф plus IFN-γ; 5, Ad-shA20-Mф plus IgG; or 6, Ad-shA20-Mф plus anti-IFN-γ. Two weeks after the 2^nd immunization, inguinal lymph nodes were harvested to analyze expression of granzyme B in CD4⁺ T cells (<b>A</b>) (p<0.05, shA20-Mф+ anti-IFN-γ immunization vs. shA20-Mф+IgG immunization; p<0.01, con-Mф+ IFN-γ immunization vs. con-Mф immunization) or CD8⁺ T cells (<b>B</b>) (p<0.01, shA20-Mф+ anti-IFN-γ immunization vs. shA20-Mф+IgG immunization; p<0.05, con-Mф+ IFN-γ immunization vs. con-Mф immunization) by ICS assay.</p