bluuebunny/crossref_metadata_2025_split huggingface dataset:
DIPG-39. New preclinical models for Diffuse Midline Glioma
Authors: Klenner Marbod , Freidel Pia , Filbin Mariella G , Beck Alexander 
Published: June 2022

Abstract
Malignant brain tumors are the leading cause of childhood death in Germany, with Diffuse Midline Glioma (DMG) being the most lethal of all paediatric brain tumors. Current treatment strategies are limited to irradiation which prolongs survival only by a few months. Preclinical studies have identified effective drug candidates, but translation into the clinic remains a major obstacle. It is known that interactions between tumor cells and components of the TME (tumor microenvironment), such as cell to cell contacts between malignant and non-malignant cells or secreted factors, can increase therapy resistance and progression of brain tumors. However, these important factors are not present in most conventional cell culture models for drug testing. Consequently, there is a need for more realistic DMG models to improve the relevance and translational potential of current drug screening. Therefore, the goal of this study was to develop a new DMG model for drug testing, consisting of induced pluripotent stem cell (iPSC) derived human brain cells and patient derived DMG cells to better mimic the complex tumor microenvironment. We co-cultured three-dimensional cerebral organoids with DMG tumor spheres resulting in the formation of DMG-Brain-Organoids (DBO). Preliminary results show that co-culture induces distinct tumor cell subpopulations corresponding to those detected in DMG tumors by single cell RNA sequencing (Filbin et al., 2018). These subpopulations mainly differ in their proliferative capacity and their differential response to clinical interventions may be critical for therapeutic success. DBOs subjected to drug treatments (single or combination) were sectioned and individual therapy effects on tumor cell subpopulations and proliferative capacity were monitored using multiplexed immunofluorescence imaging. By observing drug effects in a realistic setup, we hope to improve the predictive power of our preclinical drug screens and to find new combination therapies for DMG.
DIPG-40. Combined pharmacological and genetic screening to identify dependencies and combinations in ACVR1-mutant diffuse midline glioma
Authors: Rogers Rebecca , Carvalho Diana , Grabovska Yura , Fernandez Elisabet , Izquierdo Elisa , Mackay Alan , Jones Chris 
Published: June 2022

Abstract
Somatic mutations in ACVR1, which encodes the serine/threonine kinase ALK2, are found in 20-25% of DMG-H3K27 patients. Treatment of ACVR1-mutant patient-derived models with multiple chemotypes of ALK2 inhibitors (ALK2i) results in reduced cell viability in vitro and extended survival in orthotopic xenografts in vivo but, as single agents, these inhibitors were unable to achieve a complete anti-tumour response. Recently we reported that combinatorial treatment of ACVR1-mutant DIPG cells with vandetanib (RTK inhibitor) and everolimus (mTOR/ABC transporter inhibitor) was synergistic both in vitro and in vivo and was shown to be a feasible combination to trial clinically in this setting. To identify specific dependencies in ACVR1-mutant cells which may be translatable with novel synergistic drug combinations alongside ALK2i, we have implemented both candidate and unbiased drug and genetic screening approaches. Using a panel of patient-derived ACVR1-mutant and wild-type models, we identified synergy between multiple chemotypes of ALK2i (M4K2009/LDN-214117) and PI3K/mTOR (AZD8055/everolimus) and MEK inhibitors (trametinib), reflecting the common co-segregation of PIK3CA/PIK3R1 alterations in these tumours. Whole-genome CRISPR/Cas9 screening of ACVR1-mutant SU-DIPG-IV cells in combination with two ALK2i (M4K2009/LDN-193189), confirmed a specific MTOR genetic dependency, as well as for the protein phosphatase regulatory subunit PPP2R1A, known to play a role in MAPK pathway activation. Additional hits include the serine/threonine kinase PKMYT1, a negative regulator of the G2/M checkpoint via a functionally redundant phosphorylation of CDK1/CCNB1 alongside WEE1; confirmatory drug assays with the WEE1 inhibitor AZD1775 resulted in a synergistic interaction with ALK2i in ACVR1-mutant cells. Hits were integrated with DepMap using ‘gene-effect’ scores (Chronos) enabling filtering of common essential genes. Preliminary pathway enrichment analysis (MAGeCKFlute) identified ALK2i-specific vulnerabilities involving TGFB1/SMAD signalling and histone deacetylation. These data highlight functionally rational and novel combinatorial possibilities for children with ACVR1-mutant DMG, with systematic preclinical assessment required for prioritisation for the clinic.
DIPG-47. TSO500ctDNA sequencing reveals oncogenic mutations and copy number variations in the liquid biome of children with diffuse midline glioma
Authors: Bonner Erin R , Harrington Robin , Eze Augustine , Bornhorst Miriam , Kline Cassie N , Dawood Adam , Das Biswajit , Chen Li , Pauly Rini , Williams P Mickey , Karlovich Chris , Peach Amanda , Howell D'Andra , Doroshow James , Kilburn Lindsay , Packer Roger J , Mueller Sabine , Nazarian Javad 
Published: June 2022

Abstract
BACKGROUND: Molecular profiling of childhood CNS tumors is critical for diagnosis and clinical management, yet tissue access is restricted due to sensitive neuroanatomical locations. Moreover, CNS tumors including diffuse midline glioma (DMG) exhibit mutational heterogeneity and clonal evolution, which cannot be captured by upfront diagnostic biopsy alone. To address the lack of tumor visibility, and tprovide opportunity for longitudinal sampling, we validated and optimized a commercially available deep sequencing platform for analysis of circulating tumor DNA (TSO500ctDNATM). METHODS: In a proof-of-concept study, we defined the sensitivity, specificity, and clinical relevance of our novel ctDNA platform via analysis of paired tissue, CSF, and blood from children with DMG (n=10). Paired samples were assessed for concordance and sequencing results were compared to digital droplet PCR (ddPCR) detection of prognostic H3K27M mutation. RESULTS: DMG associated mutations in genes including H3-3A, H3C2, TP53, and ACVR1 were detected in ctDNA, including in CSF samples with low (&lt;5ng) starting DNA input. Of 9 H3K27M mutations identified in tumor, 8 were present in CSF and 3 in plasma/serum, for a positive percent agreement with tumor results of 89% and 33%, respectively. Among CSF samples, H3.3K27M was detected in 6/6 cases, and H3.1K27M in 2/3 cases, with variant allele frequencies comparable to ddPCR results. CNVs including PDGFRA, KIT, and MDM4 gains were detected in CSF and paired tumor. Low frequency events including ACVR1, PIK3CA activating mutations and KRAS amplification were detected in CSF but absent from paired tumor, indicating tissue heterogeneity. Strategies to optimize ctDNA detection, including optimization of ctDNA isolation and adjustment of library QC metrics, were identified. CONCLUSION: Targeted ctDNA deep sequencing is feasible, can inform on clinically relevant tumor mutation and CNV profiling, and provides an opportunity for longitudinal monitoring of tumor genomic evolution in the liquid biome of children with CNS tumors.
DIPG-49. International preclinical drug discovery and biomarker program informing an adoptive combinatorial trial for DMG
Authors: Nazarian Javad , Dun Matthew , Kilburn Lindsay , Waszak Sebastian , Vitanza Nicholas , Franson Andrea , Prados Mike , Raabe Eric , Firestein Ron , Beck Alexander , Saratsis Amanda , Rotblat Barak , van Vuurder Dannis , Foster Jessica , Hulleman Esther , Kline Cassie , Gupta Nalin , Cain Jason , Koschmann Carl , Muller Sabine 
Published: June 2022

Abstract
INTRODUCTION: DMG-ACT (DMG- multi-arm Adaptive and Combinatorial Trial) will implement an innovative clinical trial design of combinatorial arms for patients with DMG at all disease stages, that is adaptive to pre-clinical and correlate data generated in eight collaborating institutions. The goal of the team is to rapidly identify and validate i) promising drugs and drug combinations for clinical use, and ii) predictive biomarkers of promising drugs. METHODS: In vitro (n=30) and in vivo (n=8) models of DMG across fourteen institutions were used to assess single and combination treatment of over 80 drugs and drug combinations. Predictive biomarkers of response for top candidate drugs were identified using extensive molecular assays including proteomics, CRISPR, RNAseq, ELISA, FACS, and IHC. RESULTS: Inhibitory concentration (IC50) of all drugs were established and validated across all participating sites. In vivo validation of single and combination drug assays confirmed drug efficacy as increased survival for: ONC201 (p=0.01), ONC206 (p=0.01), ONC201+ONC206 (p=0.02), ONC201+panobinostat (p=0.01). Marizomib was highly toxic in murine PDX and zebrafish larvae assays. Murine pharmacokinetic analysis showed peak brain levels of ONC201, and ONC206 above pre-clinical IC50 concentrations. Molecular testing and analyses of existing drug screen across 578 cancer cells validated mitochondrial stress and additional proteins, as the main targets induces by ONC201/6. CONCLUSION: Thorough preclinical testing in a multi-site laboratory setting identified promising therapeutics for DMGs, resulting in launch of two clinical trials (PNOC022, ONOC023). Validation of identified biomarkers are ongoing using clinical specimen as well as in vivo PDX models.
DIPG-55. Increasing the drug-tumor resonance time in DMG murine models significantly extends survival
Authors: Power Erica , Zhang Liang , Rechberger Julian , Oh Juhee , Elmquist William , Daniels David 
Published: June 2022

Abstract
H3K27-altered diffuse midline glioma (DMG) is a uniformly lethal CNS cancer that predominately occurs in children. In the last decade, while studies revealing the molecular underpinnings of the disease have paved the way for novel therapeutic strategies, this tumor remains a death sentence. Our lab and others have identified numerous drugs of high interest for treating this devasting disease, however, every trial has failed to show benefit. Is our failure to translate these laboratory findings due to the fact we have not found the right drugs or treatment regimens yet? Or is this a failure to get the drugs to the tumor? Or is this simply a very bad disease to treat? The answer is likely multifactorial. Our lab, in collaboration with others, have strong data to show that simply getting drugs to the tumor will not result in a positive benefit. Most drugs are rapidly cleared from their target space. Utilizing techniques that increase the drug-tumor resonance time is necessary to translate our basic science findings to our patients. Picking the right drug and the delivery mechanism is not enough for a positive effect. Here, we assessed the efficacy of a previously identified inhibitor, alisertib, delivered by short-term convection-enhanced delivery or a continuous osmotic pump and found that continuous, direct delivery results in a significant increase in survival (p = 0.0002). Furthermore, long-term survivors showed a decreased tumor burden and on-target drug effects. These data support that translation into patients must consider three factors: 1) selection of a potent therapy, 2) selection of the proper delivery method for that therapy, 3) modulation to ensure that the therapy remains in the targeted tissue long enough for desired effect. Keeping these basic tenets at the forefront of development may finally lead to a more effective treatment strategy for this devastating disease
DIPG-58. Therapeutic HDAC targeting in hypermutant CNS tumors
Authors: Myers Carrie , Noll Alyssa , Biery Matthew , Meechan Michael , Tahiri Sophie , Foster Jessica , Dun Matthew , Olson James , Vitanza Nicholas 
Published: June 2022

Abstract
Diffuse intrinsic pontine glioma (DIPG) is a universally fatal tumor of the pons, most often characterized by mutations in genes encoding histone 3, that led to the classification diffuse midline glioma, H3 K27M-mutant (DMG). However, 15% of DIPG are histone wildtype (H3WT) and can have a hypermutant phenotype, characterized by mutations in DNA mismatch repair that also occur in pediatric high-grade glioma (pHGG). We previously published the preclinical efficacy of quisinostat in DMG. As hypermutant CNS tumors share transcriptional disruption with DMG, we investigated if HDAC inhibition was also therapeutic against hypermutant DIPG and pHGG. We tested PBT-24, a PMS2 mutant, treatment-naïve, patient-derived hypermutant DIPG model, and found similar quisinostat sensitivity compared to other DMG cultures in vitro (IC50 = ~30 nM), as well as significant efficacy in a xenograft flank model (60 day mean tumor size of 1109mm3 [vehicle] vs. 19mm3 [quisinostat-treated]). This in vivo effect was greater than the anti-tumor effect observed in a xenograft flank non-hypermutant DMG model PBT-09 (60 day mean tumor size of 1006mm3 [vehicle] vs. 244mm3 [quisinostat-treated]). To validate the effect of hypermutation on sensitivity to quisinostat, we generated PMS2 knock-out (KO) and MSH2 KO isogenic cell lines using the H3WT model VUMC-DIPG-10. In a xenograft flank model, we observed increased quisinostat sensitivity in the KO models (20 day mean tumor volume of 547mm3 [parental], 396mm3 [PMS2 KO], and 150mm3 [MSH2 KO]). RNA sequencing of quisinostat-treated PBT-24 revealed an increase in acute inflammatory response genes which we are investigating as a mechanism of action for HDACi against hypermutant tumors. Ultimately, we demonstrate the in vivo efficacy of quisinostat against hypermutant DIPG that supports the investigation of HDAC inhibition as a treatment strategy across hypermutant CNS tumors.
DDEL-02. Intra-arterial Delivery for Novel Combinatorial Chemotherapies in Choroid Plexus Carcinoma
Authors: Martin Brice , Garman Tyler , Laramee Madeline , Wang Amy , Hagen Natalie , Dahmane Nadia , Thomas Craig , Souweidane Mark 
Published: June 2022

Abstract
Choroid plexus carcinoma (CPC) is a rare infantile brain tumor with an aggressive clinical course that often leaves children with debilitating side effects due to aggressive and toxic chemotherapies. New delivery routes such as intra-arterial (IA) route are being explored to limit toxicity and improve efficacy. To identify novel compounds that may be used in this context, we conducted a high-throughput screen (HTS) informing on the cytotoxicity of 2454 compounds, including some currently approved for IA in other brain tumors, that identified multiple active drugs on a human primary CPC cell line. Key molecular targets previously identified in CPC literature such as mTOR, PDGFR, ATR, CDK, FGFR1 and PI3K were enriched relative to other targets in the screen. Importantly, a combination screen with a wide variety of targets revealed multiple synergistic combinations. We examined two key combinations (topotecan/elimusertib and melphalan/elimusertib) based on mechanistic alignment and translational potential through extended in vitro validation and transcriptome analyses. Pharmacokinetic assays established increased drug brain penetrance with IA delivery when compared with intravenous delivery. Ultimately, a single intra-arterial administration of melphalan combined with systemic administration of elimusertib led to a significant increased survival in a CPC genetic mouse model. This study underscores the efficacy of IA delivery and identifies a promising therapeutic option for the treatment of CPC.
DDEL-04. Pharmacokinetic/Pharmacodynamic analysis of the DNA methyltransferase inhibitor 5-azacytidine shows adequate brain tissue penetration with intravenous administration in a DIPG mouse patient-derived xenograft model.
Authors: Groves Andrew , Jones Kristen , Cameron Amy , Panditharatna Eshini , Morrow Murry , Mozarsky Brett , McCully Cynthia , Peer Cody , De Nguyen Quang- , Filbin Mariella , Warren Katherine 
Published: June 2022

Abstract
One of the biggest obstacles in developing effective therapies for CNS tumors is drug delivery due to the enigmatic challenge of penetrating the blood-brain barrier. 5-azacytidine is a DNA methyltransferase inhibitor which was the first epigenetic targeting chemotherapeutic approved by the FDA. Altered DNA methylation is a hallmark of many cancers, including diffuse intrinsic pontine glioma (DIPG). 5-azacytidine has been shown to be active in DIPG cell lines, with only modest in-vivo activity. We have previously shown in a non-human primate model that intravenous (IV) administration of 5-azacitidine does not result in measurable CSF penetration, while intrathecal (IT) administration does and is well tolerated. To follow up these studies in a tumor-bearing mouse model (HSJD DIPG007), we performed pharmacokinetic (PK) and pharmacodynamic (PD) analysis following IV vs. IT administration. Forty mice were randomized to receive four weekly doses of IV 5-azacytidine (25 mg/kg), IT 5-azacytidine (40 μg), or corresponding vehicle controls. Four mice from each arm were sacrificed 30 minutes after the last dose and brain tissue was collected for PK/PD analysis. Drug concentration was quantified using ultra-high-performance liquid chromatography with tandem mass spectrometric detection, while pharmacodynamic methylation profiling was performed using the Infinium MethylationEPIC BeadChip (850K). Brain tissue concentrations were comparable between IV (7.6-58.0 pg/mg) and IT (6.9-63.9 pg/mg) dosing. Methylation profiling unexpectedly showed a significantly more pronounced pharmacodynamic effect with IV dosing vs. IT, with a mean decrease of 13.6% vs. 2.6% in global DNA methylation score (GDMS = percentage of highly methylated (beta ≥ 0.7) genomic loci) compared to vehicle controls. For the remaining mice, there was no significant difference in survival. Our results are encouraging that phenotypically relevant demethylating effects can be achieved in the CNS with IV 5-azacytidine administration; however, further research is needed to develop promising combination strategies in DIPG.
DDEL-06. Drug Delivery to the Pons Using Short-Pulse Focused Ultrasound and Microbubble Exposure for the Treatment of Diffuse Midline Glioma
Authors: Chattenton Dani , Rivens Ian , Jiang Zheng , Carvalho Diana M , Sujarittam Krit , Boult Jessica K R , Robinson Simon P , Jones Chris , ter Haar Gail , Choi James 
Published: June 2022

Abstract
Despite advances in understanding diffuse midline glioma (DMG-H3K27), including DIPG, there are still no effective treatments available, and the dismal clinical prognosis remains. This is partly because of tumour spread behind an intact blood brain barrier (BBB), preventing drug delivery and the reason for many drugs failing in the clinic. The use of focused ultrasound and intravenous microbubbles enables temporary increases in BBB permeability, allowing drugs to enter the targeted brain region. Building on recent research demonstrating that short pulses (&lt;5 µs) of ultrasound can deliver drugs safely and uniformly to the hippocampus, we evaluated whether a similar result was achievable in the pons of mice. Mice were exposed to ultrasound (peak-negative pressure: 0.4 MPa, pulse length: 5 cycles, centre frequency 1 MHz) emitted in bursts of 38 pulses. During exposure mice received an intravenous injection of SonoVue(R) microbubbles and a fluorescently-tagged tracer (dextran, 3 kDa), acting as a drug mimic. Dextran was successfully delivered to the pons of non-tumour-bearing mice assessed by fluorescence microscopy immediately post-treatment. Dextran delivery was repeatable and confined to the targeted pons region with a homogenous distribution, typical of short pulse ultrasound, and important for treating DMG to ensure all tumour cells receive an equal drug dose. No damage to the brain was observed after H&E staining. Panobinostat has shown promise in vitro but tolerated doses have not shown therapeutic benefit in vivo as it does not cross the BBB. The in vitro toxicity of panobinostat was confirmed in a Nestin-Tv-a/p53fl/fl, RCAS-ACVR1R206H + RCAS-H3.1K27M murine cell line, with a GI50 of 15.56 nM. The ability of focused ultrasound to deliver panobinostat across the BBB to these tumours grown orthotopically will be assessed. Overall, we hope to develop a drug delivery system, that enables therapeutics to cross the BBB, expanding treatment options for DMG.
EPCT-02. A Phase 1 Study of Mebendazole with Bevacizumab and Irinotecan in High Grade Gliomas
Authors: Krystal Julie , Hanson Derek , Donnelly Danielle , Atlas Mark 
Published: June 2022

Abstract
BACKGROUND: High grade gliomas (HGG) have a dismal prognosis despite multimodal therapy. Mebendazole (MBZ) is an anti-helminthic benzimidazole. In vitro, MBZ has efficacy in numerous cancer models and is able to cross the blood brain barrier. We conducted a phase 1 trial (NCT01837862) to evaluate the safety of MBZ in combination with bevacizumab (BVCZ) and irinotecan (CPT-11). OBJECTIVE: To determine the maximally tolerated dose of MBZ when given in combination with BVCZ and CPT-11 in children with high-grade gliomas; to describe the progression-free survival (PFS) and overall survival (OS) for this group. METHODS: Patients between 1 and 21 years of age with HGG were enrolled in a 3 + 3 design to escalating doses of MBZ in combination with BVCZ 10mg/kg/dose and CPT-11 150mg/m2/dose. Subjects were eligible upfront after completion of radiation or at the time of progression. MBZ was taken orally twice per day continuously and BVCZ and CPT-11 were given intravenously on days 1 and 15 of 28-day cycles. RESULTS: Between 2015 and 2020, 10 subjects were enrolled at MBZ 50mg/kg/day (n=3), 100mg/kg/day (n=4), and 200mg/kg/day (n=3). One subject assigned to 100mg/kg/day was not evaluable. Seven subjects had a diagnosis of diffuse midline glioma, 1 subject had anaplastic astrocytoma, and 1 subject had a spinal HGG. All subjects received radiation. There were no dose limiting toxicities. The most frequent G3/G4 adverse events were neutropenia (n=3), and lymphopenia (n= 4). The overall response rate was 33% with 2 subjects achieving a partial response and 1 subject achieving a complete response sustained for 10 months. The PFS and OS from the start of study treatment were 4.7 months and 11.4 months, respectively. CONCLUSION: MBZ was safe and well tolerated when administered with BVCZ and CPT-11 at doses up to 200mg/kg/day. Further studies are needed to determine the efficacy of this treatment.