scholarly journals MODL-12. DEVELOPMENT OF A NOVEL IMMUNOCOMPETENT MOUSE MODEL FOR DIFFUSE INTRINSIC PONTINE GLIOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii413-iii413
Author(s):  
Maggie Seblani ◽  
Markella Zannikou ◽  
Katarzyna Pituch ◽  
Liliana Ilut ◽  
Oren Becher ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Mouse Model ◽  
Growth Factor Receptor ◽  
Diffuse Intrinsic Pontine Glioma ◽  
Pontine Glioma ◽  
Time Of Application ◽  
Tumor Associated Antigen ◽  
Sarcoma Virus

Abstract Diffuse intrinsic pontine glioma (DIPG) is a devastating brain tumor affecting young children. Immunotherapies hold promise however the lack of immunocompetent models recreating a faithful tumor microenvironment (TME) remains a challenge for development of targeted immunotherapeutics. We propose to generate an immunocompetent DIPG mouse model through induced overexpression of interleukin 13 receptor alpha 2 (IL13Rα2), a tumor-associated antigen overexpressed by glioma cells. A model with an intact TME permits comprehensive preclinical assessment of IL13Rα2-targeted immunotherapeutics. Our novel model uses the retroviral avian leucosis and sarcoma virus (RCAS) for in vivo gene delivery leading to IL13Rα2 expression in proliferating progenitor cells. Transfected cells expressing IL13Rα2 and PDGFB, a ligand for platelet derived growth factor receptor, alongside induced p53 loss via the Cre-Lox system are injected in the fourth ventricle in postnatal pups. We validated the expression of PDGFB and IL13Rα2 transgenes in vitro and in vivo and will characterize the TME through evaluation of the peripheral and tumor immunologic compartments using immunohistochemistry and flow cytometry. We confirmed expression of transgenes via flow cytometry and western blotting. Comparison of survival dynamics in mice inoculated with PDGFB alone with PDGFB+IL13Rα2 demonstrated that co-expression of IL13Rα2 did not significantly affect mice survival compared to the PDGFB model. At time of application, we initiated experiments to characterize the TME. Preliminary data demonstrate establishment of tumors within and adjacent to the brainstem and expression of target transgenes. Preclinical findings in a model recapitulating the TME may provide better insight into outcomes upon translation to clinical application.

scholarly journals EXTH-46. ARTIFICIAL INTELLIGENCE-BASED IDENTIFICATION OF COMBINED VANDETANIB AND EVEROLIMUS IN THE TREATMENT OF ACVR1-MUTANT DIFFUSE INTRINSIC PONTINE GLIOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii97-ii97
Author(s):  
Diana Carvalho ◽  
Peter Richardson ◽  
Nagore Gene Olaciregui ◽  
Reda Stankunaite ◽  
Cinzia Emilia Lavarino ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Cell Viability ◽  
Xenograft Model ◽  
Diffuse Intrinsic Pontine Glioma ◽  
Pontine Glioma ◽  
Serine Threonine Kinase ◽  
Orthotopic Xenografts ◽  
Extended Survival

Abstract Somatic mutations in ACVR1, encoding the serine/threonine kinase ALK2 receptor, are found in a quarter of children with the currently incurable brain tumour diffuse intrinsic pontine glioma (DIPG). Treatment of ACVR1-mutant DIPG patient-derived models with multiple inhibitor chemotypes leads to a reduction in cell viability in vitro and extended survival in orthotopic xenografts in vivo, though there are currently no specific ACVR1 inhibitors licensed for DIPG. Using an Artificial Intelligence-based platform to search for approved compounds which could be used to treat ACVR1-mutant DIPG, the combination of vandetanib and everolimus was identified as a possible therapeutic approach. Vandetanib, an approved inhibitor of VEGFR/RET/EGFR, was found to target ACVR1 (Kd=150nM) and reduce DIPG cell viability in vitro, but has been trialed in DIPG patients with limited success, in part due to an inability to cross the blood-brain-barrier. In addition to mTOR, everolimus inhibits both ABCG2 (BCRP) and ABCB1 (P-gp) transporter, and was synergistic in DIPG cells when combined with vandetanib in vitro. This combination is well-tolerated in vivo, and significantly extended survival and reduced tumour burden in an orthotopic ACVR1-mutant patient-derived DIPG xenograft model. Based on these preclinical data, three patients with ACVR1-mutant DIPG were treated with vandetanib and everolimus. These cases may inform on the dosing and the toxicity profile of this combination for future clinical studies. This bench-to-bedside approach represents a rapidly translatable therapeutic strategy in children with ACVR1 mutant DIPG.

scholarly journals Diffuse intrinsic pontine glioma: current insights and future directions

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Dilakshan Srikanthan ◽  
Michael S. Taccone ◽  
Randy Van Ommeren ◽  
Joji Ishida ◽  
Stacey L. Krumholtz ◽  
...  
Keyword(s):  
Brain Tumor ◽  
Gene Mutations ◽  
Pediatric Brain Tumor ◽  
Diffuse Intrinsic Pontine Glioma ◽  
Pontine Glioma ◽  
Current Standard ◽  
In Vivo Models ◽  
Landscape Models

AbstractDiffuse intrinsic pontine glioma (DIPG) is a lethal pediatric brain tumor and the leading cause of brain tumor–related death in children. As several clinical trials over the past few decades have led to no significant improvements in outcome, the current standard of care remains fractionated focal radiation. Due to the recent increase in stereotactic biopsies, tumor tissue availabilities have enabled our advancement of the genomic and molecular characterization of this lethal cancer. Several groups have identified key histone gene mutations, genetic drivers, and methylation changes in DIPG, providing us with new insights into DIPG tumorigenesis. Subsequently, there has been increased development of in vitro and in vivo models of DIPG which have the capacity to unveil novel therapies and strategies for drug delivery. This review outlines the clinical characteristics, genetic landscape, models, and current treatments and hopes to shed light on novel therapeutic avenues and challenges that remain.

scholarly journals Preclinical and clinical evaluation of German-sourced ONC201 for the treatment of H3K27M-mutant diffuse intrinsic pontine glioma

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Ryan J Duchatel ◽  
Abdul Mannan ◽  
Ameha S Woldu ◽  
Tom Hawtrey ◽  
Phoebe A Hindley ◽  
...  
Keyword(s):  
Biological Activity ◽  
High Resolution Mass Spectrometry ◽  
The United States ◽  
Diffuse Intrinsic Pontine Glioma ◽  
Resonance Spectroscopy ◽  
Pontine Glioma ◽  
Drug Bioavailability ◽  
Proliferation And Apoptosis

Abstract Background Diffuse intrinsic pontine glioma (DIPG) is a fatal childhood brainstem tumor for which radiation is the only treatment. Case studies report a clinical response to ONC201 for patients with H3K27M-mutant gliomas. Oncoceutics (ONC201) is only available in the United States and Japan; however, in Germany, DIPG patients can be prescribed and dispensed a locally produced compound—ONC201 German-sourced ONC201 (GsONC201). Pediatric oncologists face the dilemma of supporting the administration of GsONC201 as conjecture surrounds its authenticity. Therefore, we compared GsONC201 to original ONC201 manufactured by Oncoceutics Inc. Methods Authenticity of GsONC201 was determined by high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. Biological activity was shown via assessment of on-target effects, in vitro growth, proliferation, and apoptosis analysis. Patient-derived xenograft mouse models were used to assess plasma and brain tissue pharmacokinetics, pharmacodynamics, and overall survival (OS). The clinical experience of 28 H3K27M+ mutant DIPG patients who received GsONC201 (2017–2020) was analyzed. Results GsONC201 harbored the authentic structure, however, was formulated as a free base rather than the dihydrochloride salt used in clinical trials. GsONC201 in vitro and in vivo efficacy and drug bioavailability studies showed no difference compared to Oncoceutics ONC201. Patients treated with GsONC201 (n = 28) showed a median OS of 18 months (P = .0007). GsONC201 patients who underwent reirradiation showed a median OS of 22 months compared to 12 months for GsONC201 patients who did not (P = .012). Conclusions This study confirms the biological activity of GsONC201 and documents the OS of patients who received the drug; however, GsONC201 was never used as a monotherapy.

scholarly journals ABC Transporter Inhibition Plus Dexamethasone Enhances the Efficacy of Convection Enhanced Delivery in H3.3K27M Mutant Diffuse Intrinsic Pontine Glioma

Neurosurgery ◽  
2019 ◽  
Vol 86 (5) ◽  
pp. 742-751 ◽  
Author(s):  
Vadim Tsvankin ◽  
Rintaro Hashizume ◽  
Hiroaki Katagi ◽  
James E Herndon ◽  
Christopher Lascola ◽  
...  
Keyword(s):  
Abc Transporter ◽  
Kinase Inhibitor ◽  
Mutant Cell ◽  
Diffuse Intrinsic Pontine Glioma ◽  
Pontine Glioma ◽  
Convection Enhanced Delivery ◽  
P Glycoprotein ◽  
Magnetic Resonance Imaging Mri

Abstract BACKGROUND An impermeable blood–brain barrier and drug efflux via ATP-binding cassette (ABC) transporters such as p-glycoprotein may contribute to underwhelming efficacy of peripherally delivered agents to treat diffuse intrinsic pontine glioma (DIPG). OBJECTIVE To explore the pharmacological augmentation of convection-enhanced delivery (CED) infusate for DIPG. METHODS The efficacy of CED dasatinib, a tyrosine kinase inhibitor, in a transgenic H3.3K27M mutant murine model was assessed. mRNA expression of ABCB1 (p-glycoprotein) was analyzed in 14 tumor types in 274 children. In Vitro viability studies of dasatinib, the p-glycoprotein inhibitor, tariquidar, and dexamethasone were performed in 2 H3.3K27M mutant cell lines. Magnetic resonance imaging (MRI) was used to evaluate CED infusate (gadolinium/dasatinib) distribution in animals pretreated with tariquidar and dexamethasone. Histological assessment of apoptosis was performed. RESULTS Continuous delivery CED dasatinib improved median overall survival (OS) of animals harboring DIPG in comparison to vehicle (39.5 and 28.5 d, respectively; P = .0139). Mean ABCB1 expression was highest in K27M gliomas. In Vitro, the addition of tariquidar and dexamethasone further enhanced the efficacy of dasatinib (P < .001). In Vivo, MRI demonstrated no difference in infusion dispersion between animals pretreated with dexamethasone plus tariquidar prior to CED dasatinib compared to the CED dasatinib. However, tumor apoptosis was the highest in the pretreatment group (P < .001). Correspondingly, median OS was longer in the pretreatment group (49 d) than the dasatinib alone group (39 d) and no treatment controls (31.5 d, P = .0305). CONCLUSION ABC transporter inhibition plus dexamethasone enhances the efficacy of CED dasatinib, resulting in enhanced tumor cellular apoptosis and improved survival in H3.3K27M mutant DIPG.

scholarly journals 09 Could DLX2 regulation of neural progenitor cell fate contribute to differentiation of diffuse intrinsic pontine glioma (DIPG)?

2018 ◽  
Vol 45 (S3) ◽  
pp. S16-S16
Author(s):  
M Nevin ◽  
X Song ◽  
S Japoni ◽  
J Zagozewski ◽  
Q Jiang ◽  
...  
Keyword(s):  
Cell Fate ◽  
Neural Progenitor Cell ◽  
Diffuse Intrinsic Pontine Glioma ◽  
Gabaergic Interneuron ◽  
Acid Decarboxylase ◽  
Pontine Glioma ◽  
Double Knockout ◽  
Promoter Sequences

Introduction: Diffuse intrinsic pontine glioma (DIPG) is refractory to therapy. The identification of histone H3.1/H3.3 K27M mutations in most DIPG has provided new insights. The DLX homeobox genes are expressed in the developing forebrain. The Dlx1/Dlx2 double knockout (DKO) mouse loses tangential GABAergic interneuron migration to the neocortex. We have identified genes that encode glutamic acid decarboxylase (GAD) enzymes as direct targets of DLX1/DLX2. In DIPG patients with H3.3 K27M mutations there is decreased Dlx2 and increased expression of the myelin transcription factor, Myt1. Methods and Results: We used bioinformatics approaches and chromatin immunoprecipitation (ChIP) assays to identify Olig2, Nkx2.2 and Myt1 promoter sequences as candidate DLX2 targets in vivo. DNA binding specificity was confirmed. The functional consequences of Dlx2 co-expression with reporter constructs of ChIP-isolated promoter fragments of Olig2 and Nkx2.2 demonstrated repression of gene targets in vitro. qPCR showed increased Olig2 and Nkx2.2 expression in the DKO forebrain. Stable transfection of a murine DIPG cell line with Dlx2 resulted in increased Gad1 and Gad2 and decreased Olig2 and Nkx2.2 expression. Of significance, we demonstrated decreased expression of H3.3 K27M and restoration of H3.3 K27 tri-methylation (me3). Conclusions: DLX transcription factors promote GABAergic interneuron and concomitant inhibition of oligodendroglial differentiation in neural progenitors by repression of a suite of genes including Olig2 and Nkx2.2. Restoration of H3 K27me3 expression in DIPG provides a promising lead towards exploration of differentiation as a therapeutic strategy for DIPG.

Role of Il-2, Il-7, and IL-15 in T Cell Mediated Graft-vs-Leukemia Against Human Acute Lymphoblastic Leukemia in a NOD/scid Chimeric Mouse Model.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 5256-5256
Author(s):  
Doug Cipkala ◽  
Kelly McQuown ◽  
Lindsay Hendey ◽  
Michael Boyer
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
T Cells ◽  
Mouse Model ◽  
Scid Mouse ◽  
In Vitro Cytotoxicity ◽  
Scid Mouse Model

Abstract The use of cytotoxic T-lymphocytes (CTL) has been attempted experimentally with various tumors to achieve disease control. Factors that may influence GVT include CTL cytotoxicity, ability to home to disease sites, and survival of T cells in the host. The objective of our study is to evaluate the GVL effects of human alloreactive CTL against ALL in a chimeric NOD/scid mouse model. CTL were generated from random blood donor PBMCs stimulated with the 697 human ALL cell line and supplemented with IL-2, -7, or -15. CTL were analyzed for in vitro cytotoxicity against 697 cells, phenotype, and in vitro migration on day 14. NOD/scid mice were injected with 107 697 ALL cells followed by 5x106 CTL. Mice were sacrificed seven days following CTL injection and residual leukemia was measured in the bone marrow and spleen via flow cytometry. The ratios of CD8/CD4 positive T cells at the time of injection were 46/21% for IL-2, 52/31% for IL-7, and 45/14% for IL-15 cultured CTL (n=13). Control mice not receiving CTL had a baseline leukemia burden of 2.01% and 0.15% in the bone marrow and spleen, respectively (n=15). Mice treated with IL-15 cultured CTL had a reduction in tumor burden to 0.2% (n=13, p=0.01) and 0.05% (n=13, p=0.01) in bone marrow and spleen, respectively. Those treated with IL-2 or IL-7 cultured CTL showed no significant difference in leukemia burden in either the bone marrow (IL-2 1.28%, Il-7 5.97%) or spleen (IL-2 0.4%, IL-7 0.33%). No residual CTL could be identified in the bone marrow or spleen at the time of sacrifice in any CTL group. CTL grown in each cytokine resulted in similar in vitro cytotoxicity at an effector:target ratio of 10:1 (IL-2 41.3%, IL-7 37.7%, IL-15 45.3%, n=12–15, p>0.05 for all groups) and had statistically similar intracellular perforin and granzyme-B expression. In vitro CTL migration to a human mesenchymal stem cell line was greatest with IL-15 CTL (30.5%, n=4), followed by IL-7 CTL (18.9%, n=4), and least in IL-2 CTL (17.9%, n=4), though the differences were not significant. In vitro CTL migration was analyzed to an SDF-1α gradient as CXCR4/SDF-1α interactions are necessary for hematopoietic progenitor cell homing to the bone marrow. IL-15 cultured CTL showed the highest migration (48.8%, n=8) as compared to IL-2 (21.7%, n=6, p=0.048) or IL-7 CTL (35.9%, n=8, p>0.05). However, surface expression of CXCR4 measured by flow cytometry was significantly higher in IL-7 CTL (89.4%, n=9) compared to IL-2 CTL (52.2%, n=9, p<0.001) and IL-15 CTL (65.4%, n=10, p=0.002). Experiments are currently underway to further evaluate the role of CXCR4/SDF-1α in GVL. Preliminary in vivo experiments do not suggest any significant differences in CTL engraftment when evaluated at 24 hours post injection. Expression of the anti-apoptotic bcl-2 protein was greatest on IL-7 (MFI=5295, n=13) and IL-15 (MFI=4865, n=14) when compared to IL-2 CTL (MFI=3530, n=13, p=0.02 vs. IL-7, p=0.05 vs. IL-15), suggesting an increased in vivo survival ability. We hypothesize that IL-15 cultured CTL have greater GVL effects due to either higher in vivo survival, greater bone marrow homing efficiency, or both. Future experiments are planned to evaluate in vivo administration of IL-2 to enhance CTL survival in the host. In conclusion, IL-15 cultured CTL had significantly greater in vivo GVL effects compared to IL-2 and IL-7 CTL in the NOD/scid mouse model. This model can be utilized to evaluate the mechanism of T cell mediated GVL against ALL and potentially other human malignancies.

A Transgenic Mouse Model of Aggressive B-Cell Malignancy for Evaluating Anti-Human CD37 Therapeutics

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 188-188
Author(s):  
Kyle A Beckwith ◽  
Frank W Frissora ◽  
Matthew R Stefanovski ◽  
Jutta Deckert ◽  
Carlo M Croce ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
B Cells ◽  
Mouse Model ◽  
B Cell ◽  
Transgenic Mouse ◽  
In Vivo Studies ◽  
B Cell Malignancy ◽  
Cell Malignancy

Abstract Abstract 188 BACKGROUND: Introduction of the anti-CD20 antibody rituximab has led to remarkable progress in the development of targeted therapies for CLL and other B-cell malignancies. Despite prolonging patient survival, therapies targeting CD20 have not been curative. In recent years, alternative targets for therapeutic antibodies have emerged. One of the most promising targets has been CD37, which is highly expressed on malignant B-cells in chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma. The recent interest in this target has led to the generation of novel anti-CD37 therapeutics that could benefit from more extensive preclinical evaluation. However, preclinical development of these agents has been limited by the absence of appropriate leukemia animal models that provide targets expressing human CD37 (hCD37). Here we describe the development and characterization of a transgenic mouse where CLL-like leukemic B-cells express hCD37 and aggressively transplant into syngenic hosts. We demonstrate the utility of this unique mouse model by evaluating the in vivo efficacy of IMGN529, a novel antibody-drug conjugate targeting hCD37 that consists of the CD37-targeting K7153A antibody linked to the maytansinoid DM1 via the thioether SMCC linker. METHODS: The hCD37 transgenic mouse (hCD37-Tg) founder lines were generated by conventional methodology at the OSU Transgenic Facility. B-cell specific expression of hCD37 is driven by immunoglobulin heavy chain promoter and Ig-μ enhancer elements. Founder lines were evaluated by RT-PCR and flow cytometry to confirm RNA and protein expression, respectively. These lines were then crossed with the EμTCL1 mouse model of CLL to generate hCD37xTCL1 mice that develop CD5+CD19+hCD37+ leukemia. For in vivo studies, splenocytes from a leukemic hCD37xTCL1 donor were injected i.v. into healthy hCD37-Tg mice. Mice were randomly assigned to the following treatment groups (n=8–10 per group): IMGN529 conjugate, its K7153A antibody component, or negative controls (isotype antibody-DM1 conjugate or trastuzumab). Upon diagnosis of leukemia, a 10 mg/kg dose was administered i.p. and repeat doses were given 2 times per week for 3 weeks (70 mg/kg total). Peripheral blood disease was monitored by flow cytometry, using counting beads to obtain the absolute number of leukemic CD5+CD19+ B-cells. CD37 expression levels were determined by quantitative flow cytometry. In vitro cytotoxicity was evaluated after 24 hour incubation by flow cytometry with Annexin V and propidium iodide staining. RESULTS: IMGN529 and its K7153A antibody component demonstrated comparable in vitro activity against freshly isolated human CLL cells even in the absence of cross-linking agents (mean IMGN529 cytotoxicity=50.04% vs. 48.85% for K7153A; p=0.175; n=9). Both compounds also demonstrated cytotoxicity against hCD37 Tg B-cells ex vivo in a cross-linking dependent manner, and while expression of hCD37 in hCD37-Tg animals was B-cell specific, the expression levels were substantially lower than those observed in human CLL cells. In vivo studies with transferred hCD37xTCL1 splenocytes demonstrated rapid and complete depletion of CD5+CD19+ leukemic B-cells in response to IMGN529 conjugate, but not K7153A antibody treatment. After 1 week of IMGN529 treatment, peripheral blood leukemia was nearly undetectable and previously detected massive splenomegaly was no longer palpable. In contrast, leukemic counts and spleen sizes continued to increase in control cohorts. CONCLUSIONS: In summary, our group has generated a mouse model that develops a transplantable CD5+CD19+ leukemia expressing hCD37. We demonstrate the utility of this model for both in vitro and in vivo testing of therapeutics targeting hCD37. In addition, preclinical mouse studies expose the robust anti-leukemic effects of IMGN529 in this in vivo model of aggressive B-cell malignancy, despite the relatively low expression of hCD37 on the leukemic B-cells. Our engraftment model shows that IMGN529 is capable of eliminating widespread and highly proliferative mouse leukemia by a mechanism that is both CD37 antigen and conjugate dependent. Therefore, we propose that this novel therapeutic may also exhibit substantial efficacy in a wide range of human B-cell malignancies, even those with relatively low CD37 expression. [This work was supported by NIH (NM, JCB), LLS (NM, JCB) and Pelotonia (KAB)]. Disclosures: Deckert: ImmunoGen Inc.: Employment.

EXTH-58. THERAPEUTIC HDAC INHIBITION IN HYPERMUTANT DIFFUSE INTRINSIC PONTINE GLIOMA

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi176-vi176
Author(s):  
Alyssa Noll ◽  
Matt Biery ◽  
Carrie Myers ◽  
Danyelle Paine ◽  
Ye Zheng ◽  
...  
Keyword(s):  
Tumor Regression ◽  
Hdac Inhibitors ◽  
Cancer Cell Line ◽  
Residual Tumor ◽  
Diffuse Intrinsic Pontine Glioma ◽  
Cross Resistance ◽  
Pontine Glioma ◽  
Dismal Prognosis

Abstract Diffuse intrinsic pontine glioma (DIPG) continues to carry a dismal prognosis despite a growing understanding of its epigenetic regulation. While generally reclassified as diffuse midline glioma, H3 K27M-mutant (DMG), a subgroup of DIPGs do not harbor the classic histone mutation, with a further subset exhibiting a hypermutant phenotype. To evaluate whether hypermutant DIPG shares transcriptional vulnerabilities with H3K27M-mutant DMG, we screened a biopsy-derived treatment-naive PMS2 mutant DIPG model (PBT-24FH) for sensitivity to a panel of HDAC inhibitors (HDACi). In vitro evaluation of cell viability revealed the low nanomolar IC50 of quisinostat (50nM) and romidepsin (2nM). Dose-dependent increases in H3 acetylation and c-PARP were confirmed by western blot. Despite romidepsin’s superior potency in vitro, quisinostat demonstrated greater efficacy in an in vivo PBT-24FH flank study. 42 days following drug initiation, quisinostat-treated mice displayed dramatic tumor regression (mean volume= 33mm3, n= 7) compared to mice treated with romidepsin (mean volume= 669mm3, n= 7)(p= 0.005), or vehicle (mean volume= 990mm3, n= 6)(p< 0.001). Immunohistochemistry of quisinostat-treated tumors revealed few residual tumor cells displaying a low proliferative index. To evaluate cross-resistance, romidepsin-treated mice (mean volume= 1158mm3, n= 2) were switched to quisinostat treatment and displayed swift tumor regression (mean volume after 25 days of quisinostat= 419mm3), emphasizing quisinostat’s in vivo cytotoxic effect against both large tumors and tumors previously treated by another HDACi. To evaluate quisinostat’s effect on other hypermutant tumors, we tested HCT-116, a colon cancer cell line bearing a biallelic MLH1 deletion and observed similar cytotoxicity. We also aim to repeat these studies utilizing additional pediatric hypermutant high grade glioma models. Transcriptomic and proteomic investigations are underway to identify the mechanism of action underlying quisinostat-induced cytotoxicity. Ultimately, we are the first to demonstrate in vivo efficacy of the HDACi quisinostat against hypermutant DIPG, supporting further investigation and clinical advancement.

scholarly journals MODL-29. EVALUATING TUMOR-IMMUNE INTERACTIONS IN MOUSE MODELS OF DIFFUSE INTRINSIC PONTINE GLIOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii417-iii417
Author(s):  
Robin Furnish ◽  
Heather Bear ◽  
Xin Wei ◽  
Timothy Phoenix
Keyword(s):  
Mouse Models ◽  
Diffuse Intrinsic Pontine Glioma ◽  
In Vivo Studies ◽  
In Vitro Assays ◽  
Preclinical Studies ◽  
Check Point ◽  
Pontine Glioma ◽  
Therapeutic Benefits

Abstract BACKGROUND While adult gliomas show some level of immune cell infiltration, diffuse intrinsic pontine glioma (DIPG) is characterized as having an “immune cold” state. We have developed new immunocompetent mouse models of DIPG. These models faithfully recapitulate the pathological hallmarks of DIPG and provides a unique platform to investigate immune modulatory therapies and potential therapeutic benefits of check point inhibitor combination therapies. METHODS To evaluate the effects of CDK4/6 inhibition (CDK4/6i) on cell proliferation and immune interactions we performed a series of in vitro and in vivo studies using DIPG mouse models. In vitro assays included dose response curves, transcriptional profiling, and MHC1 expression. In vivo preclinical studies treated mouse models with CDK4/6i with or without immune check-point inhibitors (ICI). We also examined other candidate immune modulatory therapies in vitro. RESULTS CDK4/6i (Abemeciclib) reduced proliferation of DIPG cells derived from mouse models, and displayed a modest increase in immune activation by MHC1 expression and transcriptome. Pilot in vivo preclinical studies did not show any significant changes in DIPG proliferation or immune changes with CDK4/6i treatment, ICI treatment, or the combination of CDK4/6i + ICI. In vitro testing of other immune-modulatory drugs identified additional candidates that can be tested in vivo. CONCLUSION CDK4/6i displayed in vitro action, but lacked efficacy in DIPG mouse models in vivo. Further use of spontaneous DIPG mouse models will provide a rapid preclinical platform to evaluate in vivo tumor-immune interactions, drug efficacy, and mechanisms of resistance.

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