Search

We previously showed that derivatives of the Chinese traditional medicine indirubin promote survival in murine glioblastoma models (Williams et al. Cancer Research 2011). However, poor drug solubility hampered further development of this approach. Here we introduce PPRX-1701, a 6’-bromoindirubin acetoxime (BiA) containing drug/polymer nanoparticle formulation which can be injected intravenously at relatively high concentrations. Mechanistically, BiA is thought to act as a broadly selective serine-threonine protein kinase inhibitor, with activity against Src family kinases, GSK-3 and JAK2. Our preliminary data show that intravenous administration of PPRX-1701 is well-tolerated and can reach intracranial murine glioblastoma as assessed by luminescent reporter assays. PPRX-1701 administration leads to improved survival in the GL261 glioblastoma mouse model (median survival 30 days (control), 47 days (treated), p < 0.0001). Treatment with PPRX-1701 was associated with alterations in the tumor immune microenvironment, with reduced Tregs and pro-tumor macrophages, and increased CD8+ T cells. Further preliminary mechanistic studies have shown that PPRX-1701/BiA blocks the expression multiple immunosuppressive molecules in GBM downstream of interferon-g (IFNg) including PD-L1 and indoleamine 2,3-dioxygenase 1 (IDO1) - a key enzyme in the tryptophan–kynurenine–aryl hydrocarbon receptor (Trp–Kyn–AhR) immunosuppressive pathway. BiA promoted more effective T-cell mediated tumor cell killing using patient derived glioblastoma ex vivo co-culture models. This data supports further development of PPRX-1701 is a candidate immunotherapeutic agent for glioblastoma treatment. Ongoing pre-clinical studies are investigating combination with other relevant therapies.

Oncolytic herpes simplex virus-1 (oHSV) is novel FDA-approved immunotherapy for advanced melanoma patients in US. Also, oHSV is recently approved for the treatment of recurrent GBM in Japan. We have shown that oHSV treatment of GBM cells induces NICD cleavage and NOTCH activation in adjacent uninfected glioma cells via HSV-1 microRNA-H16 (Otani Y and Yoo JY, Clin Cancer Res, 2020), however, the consequences of NOTCH on immunotherapy in GBM is unknow. Here we have investigated the impact of oHSV-induced NOTCH signaling on the tumor microenvironment (TME). Analysis of TCGA GBM data and experimental murine models revealed NOTCH induced immunosuppressive myeloid cell recruitment and limited anti-tumor immunity. In oHSV treated tissue, viral infection educated tumor associated macrophages to secrete CCL2 which recruited monocytic myeloid derived suppressor cell (MDSC) that attenuated anti-tumor immunity. Consistent with this, CCL2 induction was also observed in serum of recurrent GBM patients treated with oHSV (NCT03152318). Importantly, blockade of NOTCH signaling reduced the oHSV induced immunosuppressive environment and activated a CD8 dependent anti-tumor memory response. These findings present the opportunities for combination therapies that can help improve therapeutic benefit and anti-tumor immunity in GBM.

High-grade gliomas are deadly cancers, and current standard-of-care has demonstrated limited success. The ability to specifically target glioma cells allows for the development of safer and more efficacious brain cancer therapy strategies. Brevican, a CNS-specific extracellular matrix protein is upregulated in glioma cells and its expression correlates with tumor progression. Particularly, a brevican isoform lacking glycosylation, B/bΔg is a unique glioma marker and not expressed in non-cancerous tissues. Therefore, B/bΔg represents a valuable target for anti-cancer strategies. Here, we describe the utilization of state-of-the-art platforms to screen a one-bead-one-compound combinatorial peptide library to discover a novel “B/bΔg-Targeting Peptides”, called BTP-7 that can bind B/bΔg with high affinity and specificity. BTP-7 displayed 260 nanomolar affinity for recombinant B/bΔg protein. Binding to a specific site on B/bΔg was confirmed in a competitive binding assay using BTP-7 functionalized with a UV-crosslinker and BTP-7 had little association with the fully glycosylated isoform of brevican (control). Scrambling of the BTP-7 sequence led to complete abrogation of B/bΔg binding. Furthermore, BTP-7 is preferentially taken up by B/bΔg-expressing glioma cells compared with non-expressing cells. We also discovered that BTP-7 can cross the blood-brain barrier in both the in vitro BBB organoid model and in mice. BTP-7 displayed 10x greater binding to intracranial GBM-6 tumors than control peptides, and 4x higher tumor uptake than in normal brain tissues. Conjugation of BTP-7 to camptothecin (an anti-tumor drug) via a cleavable linker led to increased DNA damage in intracranial GBM-6 tumors and prolonged survival in tumor-bearing mice. Our results show the potential of BTP-7 for the development of next-generation targeted therapeutics that could greatly benefit the outcome of patients with advanced brain cancer.

The use of oncolytic viruses (OV) as therapeutic agents for glioblastoma multiforme (GBM) is an emerging clinical focus. OV have the potential to reinvigorate the immune contexture in the tumor microenvironment (TME). However, current pre-clinical models are insufficient to study the immune effects of OV. Here, we describe an imaging approach using a human ex-vivo platform to study the effects of OV on tumor-associated immune cells in GBM. Using the rQNestin34.5v.1 herpes simplex virus (rQNestin) we treated human GBM ex-vivo, incorporating autologous patient-derived peripheral-blood mononucleated cells and whole tissue fragments. We treated GBM (n=10) with rQNestin, capable of expressing GFP, and profiled GFP expression as a proxy for replication. We analyzed serial sections of H&E, HSV-1, and multiplex immunohistochemistry (mIHC) to investigate the impact of rQNestin on the spatial context of the immune compartment. Cell Signaling Technology antibodies, CD3e (D7A6E™,ID:85061), CD68 (D4B9C,ID:76437), CD11c (D3V1E,49420), MHC-Class II ((HLA-DRB)LGII-612.14,NA) and Pan-keratin (C11,4545) were optimized for identifying intratumoral T-cells (CD3e+), macrophages (CD68) and dendritic cells (CD11c+MHCII+) in relation to the surrounding tissue architecture (pan cytokeratin). Using the serial-section imaging approach, we overlaid infiltration and replication of rQNestin. Additionally, strategic sectioning identified dynamic spatial alterations in the immune compartment, via visualization of the tumor-immune interface with indications of infiltration and replication. Quantitative pathology showed dynamic re-arrangement of immune cells - in spatial orientation, quantity and localization, relative to the tumor, under rQnestin pressure, ex-vivo. Here, we report that our ex-vivo human tumor model can be used to evaluate the effects of OV in the TME – not only viral replication but also the direct effect on the immune compartment. In particular, we can assess changes in immune subsets post-OV treatment in a 3-D manner, therefore providing greater insight into their spatial arrangement and distribution. These findings could develop our understanding of anti-tumor OV mechanisms.

INTRODUCTION Cytomegalovirus (CMV), a member of the betaherpesvirinae subfamily widespread in human populations has been reported to be detectable in glioblastoma (GBM). We have recently shown that CMV latent infection promotes GBM growth in a mouse model. The mechanisms involved are not well-defined and treatment responses have not been evaluated. METHODS To investigate the effects of CMV on GBM cells we performed an RNAseq study. Differentially expressed genes were identified and validated in vitro and in vivo. RESULTS RNAseq analysis showed multiple alterations induced by CMV infection of GBM cells including significant upregulation of c-MET (8.2 log2 fold change) and MGMT (3.9 log2 fold change) transcripts after CMV infection. c-MET is a tyrosine kinase receptor known to promote GBM growth, and MGMT expression leads to resistance to the alkylating agent temozolomide (TMZ). These findings were validated in vitro in both mouse and human GBM cells, and shown to be dependent on CMV-induced upregulation of NF-kB by siRNA knockdown of the essential RelA NF-kB subunit. The c-MET co-receptor CD44 was also upregulated suggesting a role for the c-MET signalling axis in CMV induced tumor progression. CMV-infected tumor cells were resistant to TMZ treatment as expected due to MGMT upregulation. Treatment of our murine GBM model with TMZ led to a significant increase in survival in control mock-infected mice (median survival 38 days control, 48 days TMZ), whereas the CMV infected mice did not respond (median survival 35 days control, 35 days TMZ; p value between TMZ treated groups = 10–4). CONCLUSIONS Our results define novel and relevant mechanisms by which CMV may influence both GBM growth and resistance to treatment. Further therapeutic and mechanistic studies are underway to investigate these pathways in the context of CMV in GBM. These data support further study of CMV targeting in GBM.

High-grade gliomas are deadly cancers, and current standard-of-care has demonstrated limited success. The ability to specifically target glioma cells can allow for the development of safer and more efficacious brain cancer therapy strategies. Brevican, a CNS-specific extracellular matrix protein is upregulated in glioma cells and its expression correlates with tumor progression. Particularly, a brevican isoform lacking glycosylation, B/bΔg is a unique glioma marker and not expressed in non-cancerous tissues. Therefore, B/bΔg represents a valuable target for anti-cancer strategies. Here, we describe the utilization of state-of-the-art platforms to screen a one-bead-one-compound combinatorial peptide library to discover a novel “B/bΔg-Targeting Peptides”, called BTP-7 that can bind B/bΔg with high affinity and specificity. BTP-7 displayed 260 nanomolar affinity for recombinant B/bΔg protein, and had little association with the fully glycosylated isoform of brevican (control). Scrambling of the BTP-7 sequence led to complete abrogation of B/bΔg binding. Furthermore, BTP-7 is preferentially taken up by B/bΔg-expressing glioma cells compared with non-expressing cells. We also discovered that BTP-7 can cross the blood-brain barrier using both the in vitro BBB organoid model and in mice. BTP-7 displayed 10x greater binding to intracranial GBM-6 tumors than control peptides, and 4x higher tumor uptake than in normal brain tissues. Conjugation of BTP-7 to camptothecin (an anti-tumor drug) via a cleavable linker led to increased DNA damage in intracranial GBM-6 tumors and prolonged survival in tumor-bearing mice. Our results show the potential of BTP-7 for the development of next-generation targeted therapeutics that could greatly benefit the outcome of patients with advanced brain cancer.

High-grade gliomas are deadly cancers, and current standard-of-care has demonstrated limited success. The ability to specifically target glioma cells can allow for the development of safer and more efficacious brain cancer therapy strategies. Brevican (BCAN), a CNS-specific extracellular matrix protein is upregulated in glioma cells and its expression correlates with tumor progression. Particularly, a membrane-bound BCAN isoform lacking normal glycosylation, called B/bΔg is a unique glioma marker and is not expressed in non-cancerous tissues. Therefore, B/bΔg represents a valuable target for anti-cancer strategies. Here, we describe the utilization of state-of-the-art technologies that we have recently developed to discover novel “B/bΔg-Targeting Peptides” (BTP). Briefly, small magnetic beads displaying B/bΔg were used to screen a one-bead-one-compound combinatorial library, enabling high-throughput labeling of library beads presenting peptide candidates with high affinity for B/bΔg. The “hit” beads were rapidly sorted using a microfluidic magnetic-activated sorter of our own design. The hits were then, exposed to cells expressing B/bΔg, and beads with the highest cell association were isolated and sequenced. Characterization of the purified peptides through kinetic binding analysis and cell uptake studies revealed BTP-7 as the lead candidate for B/bΔg binding. BTP-7 displayed 260 nanomolar affinity for recombinant B/bΔg protein, and had little association with the fully glycosylated isoform of BCAN. Scrambling of the BTP-7 sequence led to complete abrogation of B/bΔg binding. For in vivo evaluation, GBM-6 tumors derived from human patients were established intracranially in nude mice, and tumor formation was verified by MRI. Upon systemic administration, BTP-7 displayed approximately 10x greater binding to GBM-6 tumors than the control, as well as 4x higher tumor uptake compared to normal brain tissue. We are currently working on conjugating BTP-7 to a variety of toxic payload to selectively target gliomas, with the goal of improving brain cancer therapeutic efficacy that can ultimately benefit patient.

Background Combined immunotherapy approaches are promising cancer treatments. We evaluated anti-programmed cell death protein 1 (PD-1) treatment combined with gene-mediated cytotoxic immunotherapy (GMCI) performed by intratumoral injection of a prodrug metabolizing nonreplicating adenovirus (AdV-tk), providing in situ chemotherapy and immune stimulation. Methods The effects of GMCI on PD ligand 1 (PD-L1) expression in glioblastoma were investigated in vitro and in vivo. The efficacy of the combination was investigated in 2 syngeneic mouse glioblastoma models (GL261 and CT-2A). Immune infiltrates were analyzed by flow cytometry. Results GMCI upregulated PD-L1 expression in vitro and in vivo. Both GMCI and anti-PD-1 increased intratumoral T-cell infiltration. A higher percentage of long-term survivors was observed in mice treated with combined GMCI/anti-PD-1 relative to single treatments. Long-term survivors were protected from tumor rechallenge, demonstrating durable memory antitumor immunity. GMCI led to elevated interferon gamma positive T cells and a lower proportion of exhausted double positive PD1+TIM+CD8+ T cells. GMCI also increased PD-L1 levels on tumor cells and infiltrating macrophages/microglia. Our data suggest that anti-PD-1 treatment improves the effectiveness of GMCI by overcoming interferon-induced PD-L1-mediated inhibitory signals, and GMCI improves anti-PD-1 efficacy by increasing tumor-infiltrating T-cell activation. Conclusions Our data show that the GMCI/anti-PD-1 combination is well tolerated and effective in glioblastoma mouse models. These results support evaluation of this combination in glioblastoma patients.

Objective: Cytomegalovirus (CMV) is a ubiquitous member of the herpes virus family with a prevalence of between 50-100% in the human population and lifelong persistence. While usually clinically benign, severe cases are observed in neonates and immunocompromised patients. CMV has been associated with various tumors, including glioblastoma (GBM). The aim of this study is to clarify the interrelationship between CMV and GBM, as to elucidate its contribution to GBM progression. Methods: Pericytes, proneural (PN) and mesenchymal (MES) human GBM cell lines were assessed via flow cytometry for permissiveness to CMV (Towne Strain) infection. The transcriptome of infected cells was assessed using RT-qPCR and RNA-Seq analysis. Transwell migration and endothelial tube formation were evaluated in co-culture experiments. C57BL/6 mice were infected with murine CMV (MCMV-Δm157) at P2 and syngeneic GL261 tumor cells were implanted at week 14 after latency was established. Tumor composition was analyzed using flow cytometry. Murine and human brain sections were analyzed by immunofluorescence staining. Results: CMV was found to closely co-localize with tumor vessels in patient derived GBM specimens. In vitro studies confirmed a high permissiveness of pericytes for CMV infection. GBM cells, permissive for CMV infection had a proneural, rather than a mesenchymal signature. The transcription of pro-angiogenic cytokines such as IL-6, TGF-beta and angiogenesis inducing receptor PAR-1 were up-regulated upon CMV infection. Transwell assays revealed increased migration towards CMV infected cells after 48h (GBM cells towards infected pericytes: 1.5-fold (p=0.07); pericytes towards infected GBM cells: 1.48-fold (p=0.009)). Further, co-culture of human brain microvascular endothelial cells (HBMEC) and infected PN cells led to the establishment of larger (160%, p=

MicroRNAs are proving to be potent tumour suppressors in cancer. Many microRNAs are in pre-clinical and clinical validation.

INTRODUCTION MicroRNAs, single-stranded non-coding RNAs that function by reducing translation or causing degradation of target mRNAs, have been shown to play roles in multiple hallmarks of GBM, suggesting they may be of therapeutic importance. METHODS: The miRIDIAN mimic library (Dharmacon) that encompasses all human microRNAs annotated in miRBase v16.0 was used with a high-throughput imaging platform (Operetta) to identify microRNAs with potent effects on GBM cell proliferation and survival. Screens were performed in duplicate on U251 (adult) and KNS42 (paediatric) GBM cell lines. Cell number (nuclei count) was assessed 72h post-transfection and expressed as a z-score for each microRNA. MicroRNAs were considered significant candidates if their mean z-score was below zero and if it differed from that of the negative control by at least two standard deviations. Validation included RTqPCR, imaging and flow cytometry based assays. RESULTS: The functional screens resulted in approximately 100 candidates per cell line with 70% overlap between them. Based on available knowledge and potential relevance for GBM therapy, seven initial microRNAs candidates were chosen for further validation in a panel of four adult and two paediatric GBM cell lines: miR-34a-5p, miR-34b-5p, miR-34c-5p, miR-449a-5p, miR-449b-5p which all share a common seed sequence; miR-340-5p and miR-X. Of these candidates miR-X was identified as having the most potent, robust effects. MiR-X consistently caused a G2M cell cycle arrest followed by apoptosis in all cell lines and has predicted targets involved in the induction of the cytoskeleton rearrangement and non-canonical Wnt pathways following the G2M phase transition. This phenotype was specific to mimic-miR-X transfected cells. CONCLUSION: We have identified a novel potent pro-apoptotic microRNA in GBM that may be relevant for therapy. Work is ongoing to characterise the mechanism responsible for this effect and test for efficacy in vivo.

BACKGROUND: There have been several reports that have linked human cytomegalovirus (CMV) to gliomas. Although clinical trials of immunotherapy against CMV antigens found in gliomas have commenced in multiple institutions, the data linking these tumors to this virus remains controversial. METHODS: To study the controversial role of cytomegalovirus (CMV) in glioblastoma, we assessed the effects of murine CMV (MCMV) perinatal infection in a GFAP-cre; Nf1loxP/+ ; Trp53-/+ genetic mouse model of glioma (Mut3 mice). RESULTS: Early on after infection, MCMV antigen was predominantly localized in CD45+ lymphocytes in the brain with active viral replication and local areas of inflammation, but by 7 weeks there was a generalized loss of MCMV in brain, confirmed by bioluminescent imaging. MCMV-infected Mut3 mice exhibited a shorter survival time from their gliomas, when compared to control Mut3 mice, perinatally infected with mock or with a different neurotropic virus. Animal survival was also significantly shortened when orthotopic gliomas were implanted in mice perinatally infected with MCMV vs. controls. MCMV infection increased phosphorylated STAT3 (P-STAT3) levels in neural stem cells (NSCs) harvested from Mut3 mice SVZ and in vivo there was increased P-STAT3 in NSCs in MCMV-infected compared to control mice. Of relevance, human CMV (HCMV) also increased P-STAT3 and proliferation of patient-derived glioblastoma neurospheres, while a STAT3 inhibitor reversed this effect in vitro and in vivo. CONCLUSIONS: These findings thus associate CMV infection to a STAT3-dependent modulatory role in glioma formation/progression in the context of tumor suppressor mutations in mice and possibly in humans. SECONDARY CATEGORY: Neuropathology & Tumor Biomarkers.