bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Attitude Deviation of Spacecraft Subjected to Random Disturbance Torque based on Covariance Analysis
Authors: Obama Biyogo Nchama Vicente Angel , Shi Peng , Saeed Ayesha , Hassen Ahmed Yimam , Sanusi Babansoro Muhammad
Published: June 2023

The attitude stability requirements of spacecraft are closely related to their application scenarios. Spacecraft’s motion will always be affected by internal and external disturbances during its orbital movement, which makes the attitude no longer meet the stability requirements of the mission design convention. This paper focuses on the study of the effect of random disturbance torques on the spacecraft attitude. The basic covariance method is proposed to study the influence of random disturbance torques on the spacecraft attitude. The simulation results show that the method of covariance analysis can be applied to study the attitude deviation of spacecraft due to random disturbances.
Fixed-time Disturbance Observer-Based Finite-Time Backstepping Control for Hypersonic Vehicle
Authors: Zhang Bangchu , Rao Shuitao , Kuang Yu , Bai Zhuo , Zhu Weiyu
Published: June 2023

Due to the severe flight environment, hypersonic vehicles are susceptible to external disturbances and aerodynamic parameter uncertainties, dramatically challenging the precise control and stable tracking. This paper presented a fixed-time disturbance observer (FTDO) to obtain better tracking performance for hypersonic vehicles. The FTDO can improve the tracking performance under external disturbances and aerodynamic parameter perturbations, whose observation time is bounded and does not depend on the initial errors. The backstepping control can guarantee finite-time convergence with the finite-time control technique. A second-order filter is designed to process the complexity explosion problem in the traditional backstepping control and ensure the tracking system’s finite-time stability. Then with Lyapunov theory, it is proved that the control system is stable and convergent in finite time. Finally, three numerical simulation results based on typical conditions are given to show the effectiveness and advantage of the developed control scheme, and external disturbances can be estimated accurately within two seconds. These results have reference value for flight controller design of hypersonic and other aircraft in complex disturbance environments.
Impact of the gas choice and the geometry on the breakdown limits in Micromegas detectors
Authors: Gasik P. , Waldmann T. , Fabbietti L. , Klemenz T. , Lautner L. , Ulukutlu B.
Published: June 2023

In this study we investigate the stability limits of Micromegas detectors upon irradiation
with alpha particles. The results are obtained with meshes with different optical transparency and
geometry of wires. The measurements are performed in Ar- and Ne- based mixtures with different
CO2 content. We observe that the breakdown limit strongly depends on the gas and that a higher
amount of quencher in the mixture does not necessarily correlate with higher stability. In
addition, we observe discharge probability scaling with the wire pitch. This suggests that a
Micromegas mesh cell can be treated as an independent amplification unit, similar to a hole in a
GEM foil. The outcome of these studies provides valuable input for further optimization of MPGD
detectors, multi-layer stacks in particular.
Studying the impact of humidity on the performance of THGEMs
Authors: Fribert H. , Gasik P. , Ulukutlu B. , Fabbietti L.
Published: June 2023

In this study, we investigate the impact of humidity on the performance of a THGEM
operated with an Ar-CO2 gas mixture. The water content is introduced in a range of
0–4000 ppmV. It is observed that the presence of increased humidity does not degrade any of the
studied performance criteria. On the contrary, our measurements suggest an improvement in
discharge stability with increasing humidity levels at the highest gains and fields. No
significant difference is observed at the lower gains, indicating that humidity helps to avoid
spurious discharges related to electrode defects or charging-up of the insulating layers. We
conclude that adding a small amount of water to the gas mixture may be beneficial for the stable
operation of an MPGD.
Network of chiral one-dimensional channels and localized states emerging in a moiré system
Authors: Park Jeyong , Gresista Lasse , Trebst Simon , Rosch Achim , Park Jinhong
Published: June 2023

Moiré systems provide a highly tunable platform for engineering band structures and exotic correlated phases. Here, we theoretically study a model for a single layer of graphene subject to a smooth moiré electrostatic potential, induced by an insulating substrate layer. For sufficiently large moiré unit cells, we find that ultra-flat bands coexist with a triangular network of chiral one-dimensional (1D) channels. These channels mediate an effective interaction between localized modes with spin-, orbital- and valley degrees of freedom emerging from the flat bands. The form of the interaction reflects the chirality and 1D nature of the network. We study this interacting model within anSU(4) mean-field theory, semi-classical Monte-Carlo simulations, and anSU(4) spin-wave theory, focusing on commensurate order stabilized by local two-site and chiral three-site interactions. By tuning a gate voltage, one can trigger a non-coplanar phase characterized by a peculiar coexistence of three different types of order: ferromagnetic spin order in one valley, non-coplanar chiral spin order in the other valley, and 120∘order in the remaining spin and valley-mixed degrees of freedom. Quantum and classical fluctuations have qualitatively different effects on the observed phases and can, for example, create a finite spin-chirality purely via fluctuation effects.
Active learning on a programmable photonic quantum processor
Authors: Ding Chen , Xu Xiao-Yue , Niu Yun-Fei , Zhang Shuo , Huang He-Liang , Bao Wan-Su
Published: June 2023

Training a quantum machine learning model generally requires a large labeled dataset, which incurs high labeling and computational costs. To reduce such costs, a selective training strategy, called active learning (AL), chooses only a subset of the original dataset to learn while maintaining the trained model’s performance. Here, we design and implement two AL-enpowered variational quantum classifiers to investigate the potential applications and effectiveness of AL in quantum machine learning. Firstly, we build a programmable free-space photonic quantum processor, which enables the programmed implementation of various hybrid quantum-classical computing algorithms. Then, we code the designed variational quantum classifier with AL into the quantum processor, and execute comparative tests for the classifiers with and without the AL strategy. The results validate the great advantage of AL in quantum machine learning, as it saves at most

85
%

labeling efforts and

91.6
%

percent computational efforts compared to the training without AL on a data classification task. Our results inspire AL’s further applications in large-scale quantum machine learning to drastically reduce training data and speed up training, underpinning the exploration of practical quantum advantages in quantum physics or real-world applications.
Relativistic probability densities for location
Authors: Fenwick Joshua G , Dick Rainer
Published: June 2023

Imposing the Born rule as a fundamental principle of quantum mechanics would require the existence of normalizable wave functions ψ(
x
, t) also for relativistic particles. Indeed, the Fourier transforms of normalized
k
-space amplitudes

ψ
(
k
,
t
)
=
ψ
(
k
)
exp
(
−
i

ω

k

t
)

yield normalized functions ψ(
x
, t) which reproduce the standard
k
-space expectation values for energy and momentum from local momentum (pseudo-)densities ℘
μ
(
x
, t) = (ℏ/2i)[ψ
+(
x
, t)∂
μ

ψ(
x
, t) − ∂
μ

ψ
+(
x
, t) · ψ(
x
, t)]. However, in the case of bosonic fields, the wave packets ψ(
x
, t) are nonlocally related to the corresponding relativistic quantum fields ϕ(
x
, t), and therefore the canonical local energy-momentum densities


(
x
,
t
)
=
c



0

(
x
,
t
)

and


(
x
,
t
)

differ from ℘
μ
(
x
, t) and appear nonlocal in terms of the wave packets ψ(
x
, t). We examine the relation between the canonical energy density


(
x
,
t
)

, the canonical charge density ϱ(
x
, t), the energy pseudo-density



˜

(
x
,
t
)
=
c

℘

0

(
x
,
t
)

, and the Born density ∣ψ(
x
, t)∣2 for the massless free Klein–Gordon field. We find that those four proxies for particle location are tantalizingly close even in this extremely relativistic case: in spite of their nonlocal mathematical relations, they are mutually local in the sense that their maxima do not deviate beyond a common position uncertainty Δx. Indeed, they are practically indistinguishable in cases where we would expect a normalized quantum state to produce particle-like position signals, viz. if we are observing quanta with momenta p ≫ Δp ≥ ℏ/2Δx. We also translate our results to massless Dirac fields. Our results confirm and illustrate that the normalized energy density


(
x
,
t
)

/

E

provides a suitable measure for positions of bosons, whereas normalized charge density ϱ(
x
, t)/q provides a suitable measure for fermions.
Investigating the impact of working arrangements and lifestyle factor importance on environmental consciousness
Authors: Chapman Andrew , Karmaker Shamal Chandra , Shigetomi Yosuke
Published: June 2023

This study investigates the impact of people’s demographics, preferred working arrangements and utilization of their free time on environmental consciousness. Such an investigation is timely because of the changing expectations around working, and the rising popularity of work-from-home arrangements leading to increased flexibility. Although the link between income and environmental impact is well understood, the mediating factors between working arrangements and environmental concerns remain unclear. Through the analysis of a nationally representative survey conducted in Japan, we clarify people’s desire to work shorter hours, subject to the maintenance of income levels, along with a desire to consider revised working arrangements if environmental improvements can be anticipated as a result. One important finding of this research is that those who prioritize their free time for family and friends have a much higher probability of valuing the environment and thus reducing their carbon footprint. These findings have implications for policy design which encourages low impact working arrangements, the sharing economy and a family friendly society.
Crème De Menthe
Authors: Lawrence D. H.
Published: June 2023

They met again in the café several hours later. Gerald went through the push doors into the large, lofty room where the faces and heads of the drinkers showed dimly through the haze of smoke, reflected more dimly and repeated ad infinitum...
Moony
Authors: Lawrence D. H.
Published: June 2023

After his illness Birkin went to the south of France for a time. He did not write, nobody heard anything of him. Ursula, left alone, felt as if everything were lapsing out. There seemed to be no hope in the world. One was a...
Absence of infective endocarditis relapse when end-of-treatment fluorodeoxyglucose positron emission tomography/computed tomography is negative
Authors: Régis Claudine , Thy Michael , Mahida Besma , Deconinck Laurène , Tubiana Sarah , Iung Bernard , Duval Xavier , Rouzet François
Published: June 2023

Aims

In non-operated infective endocarditis (IE), relapse may impair the outcome of the disease. The aim of the study was to evaluate the relationship between end-of-treatment (EOT) fluorodeoxyglucose positron emission tomography/computed tomography FDG-PET/CT results and relapse in non-operated IE either on native or prosthetic valve.

Methods and results

We included 62 patients who underwent an EOT FDG-PET/CT for non-operated IE performed between 30 and 180 days of antibiotic therapy initiation. Qualitative valve assessment categorized initial and EOT FDG-PET/CT as negative or positive. Quantitative analyses were also conducted. Clinical data from medical charts were collected, including endocarditis team decision for IE diagnosis and relapse. Forty-one (66%) patients were male with a median age of 68 years (57; 80) and 42 (68%) had prosthetic valve IE. End-of-treatment FDG-PET/CT was negative in 29 and positive in 33 patients. The proportion of positive scans decreased significantly compared with initial FDG-PET/CT (53% vs. 77%, respectively, P < 0.0001). All relapses (n = 7, 11%) occurred in patients with a positive EOT FDG-PET/CT with a median delay after EOT FDG-PET/CT of 10 days (0; 45). The relapse rate was significantly lower in negative (0/29) than in positive (7/33) EOT FDG-PET/CT (P = 0.01).

Conclusion

In this series of 62 patients with non-operated IE who underwent EOT FDG-PET/CT, those with a negative scan (almost half of the study population) did not develop IE relapse after a median follow-up of 10 months. These findings need to be confirmed by prospective and larger studies.
Pharmacological properties and derivatives of saikosaponins—a review of recent studies
Authors: Zhu Yingchao , Lai Yu
Published: June 2023

Objectives

Saikosaponins (SSs) constitute a class of medicinal monomers characterised by a triterpene tricyclic structure. Despite their potential therapeutic effects for various pathological conditions, the underlying mechanisms of their actions have not been systematically analysed. Here, we mainly review the important anti-inflammatory, anticancer, and antiviral mechanisms underlying SS actions.

Methods

Information from multiple scientific databases, such as PubMed, the Web of Science, and Google Scholar, was collected between 2018 and 2023. The search term used was saikosaponin.

Key findings

Numerous studies have shown that Saikosaponin A exerts anti-inflammatory effects by modulating cytokine and reactive oxygen species (ROS) production and lipid metabolism. Moreover, saikosaponin D exerts antitumor effects by inhibiting cell proliferation and inducing apoptosis and autophagy, and the antiviral mechanisms of SSs, especially against SARS-CoV-2, have been partially revealed. Interestingly, an increasing body of experimental evidence suggests that SSs show the potential for use as anti-addiction, anxiolytic, and antidepressant treatments, and therefore, the related molecular mechanisms warrant further study.

Conclusions

An increasing amount of data have indicated diverse SS pharmacological properties, indicating crucial clues for future studies and the production of novel saikosaponin-based anti-inflammatory, efficacious anticancer, and anti-novel-coronavirus agents with improved efficacy and reduced toxicity.
Clinical impact of radiation-induced myocardial damage detected by cardiac magnetic resonance imaging and dose-volume histogram parameters of the left ventricle as prognostic factors of cardiac events after chemoradiotherapy for esophageal cancer
Authors: Umezawa Rei , Ota Hideki , Takagi Hidenobu , Kadoya Noriyuki , Nakajima Yujiro , Takahashi Noriyoshi , Yamamoto Takaya , Takase Kei , Jingu Keiichi
Published: June 2023

This prospective study aimed to evaluate whether radiation (RT)-induced myocardial damage by cardiac magnetic resonance (CMR) imaging could be a predictor of cardiac events after chemoradiotherapy (CRT) for esophageal cancer and determine the dose-volume histogram (DVH) parameters of the left ventricle (LV) in predicting cardiac events. CMR imaging was performed before and 6 months after CRT in patients receiving definitive CRT. RT-induced myocardial damage was defined as abnormal CMR findings indicating myocardial fibrosis corresponding to an isodose line of ≥30 Gy. The cutoff values of the LV DVH parameters were calculated using the receiver operating characteristic curve based on the presence of RT-induced myocardial damage. The prognostic factors related to cardiac events of Grade 3 or higher were examined. Twenty-three patients were enrolled in the study. RT-induced myocardial damage by late gadolinium enhancement and/or an increase of 100 ms or higher in native T1 post-CRT was detected in 10 of the 23 patients. LV V45 was the best predictive factor for RT-induced myocardial damage with a cutoff value of 2.1% and an area under the curve of 0.75. The median follow-up period was 82.1 months. The 5- and 7-year cumulative incidences of cardiac events of Grade 3 or higher were 14.7 and 22.4%, respectively. RT-induced myocardial damage and LV V45 were significant risk factors (P = 0.015 and P = 0.013, respectively). RT-induced myocardial damage is a significant predictor of cardiac events. LV V45 is associated with RT-induced myocardial damage and subsequent cardiac events.
ATRT-07. CLINICAL APPLICABILITY OF C19MC MIRNA DETECTION IN LIQUID BIOPSIES OF ETMR PATIENTS
Authors: Madlener Sibylle , Furtner Julia , Stepien Natalia , Senfter Daniel , Mayr Lisa , Zeyda Maximilian , Gramss Leon , Aistleitner Barbara , Spiegl-Kreinecker Sabine , Rivelles Elisa , Dorfer Christian , Rössler Karl , Czech Thomas , Azizi Amedeo A , Peyrl Andreas , Lötsch-Gojo Daniela , Müllauer Leonhard , Haberler Christine , Slavc Irene , Gojo Johannes
Published: June 2023

Embryonal tumor with multilayered rosettes (ETMR) is a distinct central nervous system tumor entity which is characterized by dysregulation of oncogenic micro RNAs (miRNA). In the majority of cases (approx. 90%), tumors are characterized by amplification of the C19MC locus accompanied by a fusion of this locus to the TTYH1 gene. Beside the very young age of the patients, ETMR is a highly aggressive brain tumor with a dismal clinical outcome. About half of the patients relapse within the first 6 months despite intensive therapy. Based on these facts, a more rapid diagnosis as well as more accurate and faster detection of tumor response or tumor relapse would significantly improve the management of these severely affected young patients. Liquid biopsy has emerged as a highly promising tool to enable minimal invasive detection of molecular parameters to facilitate diagnosis and patient monitoring. Here, we developed a miRNA based liquid biopsy tool and performed a comprehensive profiling of the miRNA landscape in 11 ETMR tumor tissues and matching liquid biopsy samples of patients. The screening of the initial liquid biopsy samples (plasma or serum) taken at diagnosis revealed distinctly enriched miRNA levels. Further, we evaluated the use of the miRNA levels as a longitudinal tumor-monitoring tool. We detected decreasing levels after tumor resection and in long-term survivors and vice versa increasing levels in patients with progressive tumor disease. In conclusion, we developed a reliable and fast method with a turnaround time of only 4 hours between blood draw and analysis of the aberrant expressed miRNA in liquid biopsy samples of ETMR patients correlating with the clinical course of the individual patient.
ATRT-19. RARE EMBRYONAL TUMORS INCLUDING EMBRYONAL TUMOR MULTILAYER ROSETTE, OUTCOME AND PATTERN OF TREATMENT FAILURE: MD ANDERSON CANCER CENTER EXPERIENCE
Authors: He Jiasen , Munir Faryal , Sheikh Irtiza , Johnson Jason , Paulino Arnold , McGovern Susan , Sandberg David , Zaky Wafik
Published: June 2023

Rare embryonal tumors (excluding medulloblastoma and ATRT) are aggressive pediatric cancers that include embryonal tumor with multilayer rosettes (ETMR), embryonal tumor with abundant neuropil and true rosettes (ETANTR), and embryonal tumors not otherwise specified (ET-NOS). The presence of driver events like C19MC amplification, DICER1 mutations and other microRNA-related aberrations are vital in diagnostic classification of these tumors. The prognosis of these tumors is dismal despite intensive multimodal treatments with the 5-year overall survival being less than 30%. We retrospectively reviewed 12 patients with rare embryonal tumors who were treated at MD Anderson Cancer Center from 2010 to 2022. Of the 12 patients identified, the mean age at diagnosis was 3.6 years (range: 1-12 years) with no sex differences. Histologically, they were classified into ETMR (4/12), ETANTR (3/12) and ET-NOS (5/12) with C19MC found positive in 2/4 ETMR cases. All patients presented with large infiltrative tumors to the supratentorial (6/12), brainstem (4/12), and spinal (2/12) regions. The majority of patients (10/12) were treated by gross/subtotal resection. Treatment at diagnosis included surgery alone (3/12), surgery with chemotherapy (4/12), surgery with chemotherapy plus radiation (4/12),and chemotherapy plus radiation without surgery (1/12). Five patients reported with de-novo metastasis and 10/12 patients had disease progression at 4.1 months of median follow-up (range: 1.2-10.6 months). Six patients had local recurrence and three patients had local with distant disease at progression. Eight patients are still alive, with 5/8 of them surviving more than 5 years. In conclusion, these rare embryonal tumors are hard to diagnose and treat effectively. Even with successful surgery and intense chemotherapy, almost all of them progress/relapse but combined treatments seem to be effective in a subset of patients. Collaborative multi-institutional efforts are required to define standard treatment approaches and future patient stratification.
BIOL-01. GENERATION AND MULTI-OMICS CHARACTERIZATION OF 203 PEDIATRIC CNS TUMOUR MODELS REVEALS NEW THERAPEUTIC VULNERABILITIES
Authors: Sun Claire , Daniel Paul , Chew Nicole , Shi Hui , Loi Melissa , Parackal Sarah , Koptyra Mateusz , Adjumain Shazia , Panday Monty , Habarakada Dilru , Tourchi Motahhareh , Neeman Naama , Resnick Adam , Jones Chris , Cain Jason , Firestein Ron
Published: June 2023

Pediatric Central Nervous System (CNS) tumors are the leading cause of cancer-related death among children. Identifying new targeted therapies necessitates the use of pediatric cancer models that faithfully recapitulate the patient’s disease. However, the generation and characterization of pediatric cancer models has significantly lagged adult cancers, underscoring the urgent need to develop and characterize pediatric CNS models of disease. Herein, we establish a single-site collection of 233 CNS tumour cell lines, representing 14 distinct brain childhood tumor types. We subjected >200 cell lines to multi-omics analyses (DNA-sequencing, RNA-sequencing, DNA methylation, proteomics, phospho-proteomics), and in parallel performed pharmacological and genetic CRISPR-Cas9 loss of function screens to identify pediatric-specific treatment opportunities and biomarkers. Our work provides insight into specific pathway vulnerabilities in molecularly defined pediatric tumor classes and uncovers biomarker-linked therapeutic opportunities of clinical relevance. Cell line data and resources are provided in an open access portal (vicpcc.org.au/dashboard).
BIOL-03. NOVEL GENETICALLY ENGINEERED MOUSE MODEL FOR CHOROID PLEXUS CARCINOMA MIMICS HUMAN DISEASE
Authors: Duarte Matilde de Almeida , Gilbertson Richard , Taylor Jessica , Jassim Amir , Hu Linda
Published: June 2023

Choroid plexus carcinomas (CPCs) are rare, aggressive malignant tumours of the central nervous system occurring mainly in children under the age of one. While advances in clinical and molecular stratification have enabled risk-adapted treatment planning and improvements in outcome for many types of childhood brain tumours, there has not been equivalent progress for children with CPC. This has largely been due to the low incidence, leading treatment strategies to be mostly based on case series and a “standard of care” has yet to be established. In order to elucidate a coordinated therapeutic strategy for children with CPC, it is imperative to develop in vitro and in vivo models to improve our understanding of the mechanisms underlying tumorigenesis. We hypothesised that we could develop a genetically engineered mouse model (GEMM) to recapitulate patient CPCs, allowing for an early age of onset and high penetrance rate for accurate and efficient preclinical studies. To develop this GEMM of CPC, we utilized Cre-Lox technology to target CPC cells of origin. We crossed mice that conditionally expressed Tp53 flx/flx; Rb flx/flx; Pten flx/flx with mice harbouring a Tg(Ttr-cre/Esr1*)1Vco allele, as it drives selective Cre-recombination in the early embryonic choroid plexus. Using this methodology, we have managed to produce CPCs within 90 days and with a 95% penetrance rate which we characterised using our laboratory’s tumour characterisation pipeline comprising histological evaluation, transcriptome analysis and imaging. We then used this model to investigate the transformation of the choroid during tumorigenesis and test novel therapeutic approaches to improve outcomes for patients affected by CPC. Not only are we looking for a “standard of care” that is currently inexistent for CPC, but we are also looking for one that will have minimal side effects and, therefore, not jeopardise the future of these children.
DIPG-10. DELTA-24-RGDOX PROMOTES ANTITUMOR IMMUNE RESPONSE IN DMG MODELS
Authors: Laspidea Virginia , Ausejo-Mauleon Iker , de la Nava Daniel , Nuin Sara , Hernandez-Osuna Reyes , Marco-Sanz Javier , Palacios-Alonso Daniel , Gomez-Manzano Candelaria , Fueyo Juan , Alonso Marta
Published: June 2023

Diffuse Midline Gliomas (DMG) are very aggressive brain tumors that arise in the brainstem of children. The prognosis of these patients is still dismal, with an overall survival of less than one year. DMG tumors are poorly infiltrated by the immune system, and therefore in this project, we propose the use of the oncolytic adenovirus Delta-24-RGDOX to enhance the antitumor immune response. Delta-24-RGDOX is based on the Delta-24-RGD platform and incorporates the OX40 ligand (OX40L). The binding of OX40 to OX40L leads to the co-stimulation of CD4 and CD8 cells, generating effector and memory T cells. Therefore, the aim of this project is to improve the antitumor effect of the virus, providing a greater co-stimulation in the tumor. In vitro, Delta-24-RGDOX was able to efficiently infect and express viral proteins in human and murine DMG cell lines, and to cause cell death in a dose-dependent manner. Moreover, the virus expressed OX40L on the membrane of infected cells, which was functional and capable of activating CD8 T cells. Once we confirmed that the viral administration into DMG in vivo models was safe, we evaluated the therapeutic effect of the virus. We observed a significant survival increase after Delta-24-RGDOX treatment of a DMG model at early tumor stage (P=0.0033, median OS PBS 9 vs 12 days for virus treated mice) and in already stablished tumors (P=0.018, median OS PBS 9 vs 12.5 days for virus treated mice). Importantly, tumors from treated mice (7 days after treatment) displayed a significant increase of immune infiltration compared to controls. Moreover, splenocytes from Delta-24-RGDOX treated mice were also more activated. These data demonstrated that Delta-24-RGDOX expresses OX40L on infected cells, promoting the modulation of the tumor microenvironment and leading to an improved survival outcome in DMG models.
DIPG-22. TRIPTOLIDE AS A POTENTIALLY PROMISING THERAPY FOR DIFFUSE MIDLINE GLIOMA
Authors: Ciani Ludovica , Laternser Sandra , Kritzer Bettina , Hasler Kerstin , Przystal Justyna M , Velagapudi Mohana R , Alonso Marta M , Zalacain Marta , Müller Sabine , Nazarian Javad
Published: June 2023

Diffuse Midline Gliomas (DMG) are amongst the most lethal pediatric brain tumors. Children diagnosed with DMG face a grim prognosis of 9-11 months from diagnosis. Over 85% of DMG patients harbor mutation affecting histone-encoding genes (H3.1K27M, H3.3K27M) leading to genome hypomethylation and transcriptional disruption. Despite decades of clinical studies, the development of an effective therapy remains a challenge. Triptolide is a diterpenoid triepoxide compound inhibiting cell growth and exhibiting preclinical antitumor activity. A large drug screen conducted by the NCI using DMG cell lines identified triptolide as a candidate for reducing DMG cell viability. To further investigate triptolide and its potential for clinical intervention, we used DMG preclinical in vitro and in vivo models. In vitro viability assays with triptolide alone and in combination with other therapeutic drugs (ONC201 and ONC206), were carried out using seven DMG cell lines. Single treatment with triptolide resulted in a significant decrease in DMG cell viability and combination with both ONC201 and ONC206 showed additivity. Triptolide’s toxicity was assessed in vivo through direct injections into the yolk sac of zebrafish. Preliminary data demonstrated how triptolide has higher toxicity compared to un-injected and DMSO control groups. However, a major limitation of triptolide’s clinical utility is its low solubility. Therefore, for in vivo studies, we used minnelide, a water-soluble analog of triptolide, with potent antitumor properties. Studies were performed in eleven RAG2 female mice. PDX tumor-bearing mice were treated with minnelide and ONC201 for three weeks as single or in combination. Survival studies showed no significance in minnelide monotherapy. However, minnelide + ONC201 combination therapy resulted in significant (p=0.01) survival of PDX models. Our current studies investigate the efficacy of a higher dose of minnelide in vivo. Our goal is to establish minnelide potential as a combination strategy for the treatment of children diagnosed with DMG.
DIPG-28. IDENTIFICATION AND TARGETING OF METABOLIC VULNERABILITIES IN COMBINATION WITH PDGFRA-INHIBITION IN DIFFUSE MIDLINE GLIOMA
Authors: Neyazi Sina , Gowda Pruthvi S , Trissal Maria , Fonticella Jay-Miguel , Portero Erika P , Haley-Read John-Paul , Anderson Emily P , Danial Nika N , Filbin Mariella G
Published: June 2023

Diffuse midline gliomas (DMG) are driven by self-renewing, stem-like glioma cells stalled in an oligodendrocyte precursor cell (OPC)-like state that are characterized by high expression of PDGFRA. This lineage overexpression of PDGFRA, together with commonly found genomic amplifications and mutations in PDGFRA, has been shown to cooperate with H3-K27M mutations in tumor development. Therefore, targeting PDGFRA has long been proposed as a potential treatment strategy for DMG. Our previous work revealed that Avapritinib, a small molecule inhibitor of PDGFRA, is highly effective in DMG cells in vitro and in vivo. Following these preclinical findings, nine DMG patients were treated with Avapritinib for the first time. While 50% of all treated patients experienced a strong clinical response from Avapritinib, tumor progression and treatment escape were eventually observed in most patients. Here, we investigated which mechanisms DMG cells use to escape Avapritinib treatment and explored how these resistance mechanisms can be therapeutically exploited. Transcriptional analysis of a DMG cell line previously identified as Avapritinib-resistant revealed an upregulation of genes associated with fatty acid metabolism and oxidative phosphorylation (OXPHOS) following treatment with Avapritinib. Functional assays confirmed elevated OXPHOS in Avapritinib-resistant cells with significant (i) increase in mitochondrial energy transduction, (ii) increase in palmitate- (a product of fatty acid metabolism) driven oxygen consumption rate and (iii) greater incorporation of palmitate-derived carbons into the tricarboxylic acid cycle. These metabolic changes could be genetically reproduced in the same cell line after CRISPR-Cas9-mediated knockout of PDGFRA. To determine which therapies could target the dependency of Avapritinib-resistant cells on OXPHOS and fatty acid metabolism, we performed a metabolic drug screening and identified two metabolic drugs to have synergistic cytotoxic effects with Avapritinib. Together, we revealed distinct metabolic changes in Avapritinib-resistant DMG cells and showed that targeting these metabolic vulnerabilities might further increase the clinical benefit of Avapritinib.
DIPG-32. PRECLINICAL TESTING OF THE EFFICACY AND SAFETY OF CRISPR/CAS9 GENE EDITED CAR-T CELL THERAPY FOR DIFFUSE MIDLINE GLIOMA (DMG)
Authors: Balakrishnan Ilango , Leach Lillie , Pierce Angela , Lakshmanachetty Senthilnath , Madhavan Krishna , Fosmire Susan , Chatwin Hannah , Green Adam , Fry Terry , Vibhakar Rajeev , Kohler Eric M , Venkataraman Sujatha
Published: June 2023

DMGs are highly aggressive and difficult-to-treat brain tumors in children. Recent advances in Chimeric Antigen Receptor (CAR) expressing T cell therapy suggest application for brain tumors. Recent studies also demonstrate feasibility of GD2, Her2 and B7H3 CAR-T infusions in childhood brain tumors. We identified and developed a novel CAR-T therapy, targeting the CD99 antigen, which is homogenously expressed at high levels on DMG tumor cells. These CAR-T cells showed initial clearance of tumor, but the long-term persistence and anti-tumor efficacy of these CAR-T cells in DIPG xenografts were limited due to fratricide, as T cells also express CD99. To overcome this obstacle, we have further optimized a protocol in which we first knock-out CD99 from the human donor T cells using CRISPR-cas9 gene-editing and subsequently transducing with our CD99 virus in the pure population of CD99KO T cells. Systemic delivery of these gene-edited CAR-T cells showed enhanced in vivo persistence with complete clearance of tumor in DMG mouse models, and no tumor recurrence was seen well-beyond the time frame of expected tumor recurrence after treatment with un-edited CD99 CAR-T cells. In addition, loco-regional delivery of these gene-edited CD99 CAR-T cells when administered directly to the 4th ventricle, even at a low dose, showed similar anti-tumor efficacy with significantly increased animal survival. These data suggest a regional approach analogous to Omaya reservoir administered drug in humans may be a promising alternative approach to limit any toxicity.
DIPG-42. MAPPING THE DNA METHYLATION LANDSCAPE OF DIPG REVEALS NOTABLE METHYLOME VARIABILITY RESPONSIVE TO PHARMACOLOGIC MODULATION
Authors: Tetens Ashley , Martin Allison , Arnold Antje , Novak Orlandi , Idrizi Adrian , Tryggvadottir Rakel , Craig-Schwartz Jordyn , Barbato Michael , Eberhart Charles , Resnick Adam , Koldobskiy Michael
Published: June 2023

Diffuse intrinsic pontine glioma (DIPG) is an incurable pediatric brainstem tumor, driven by the H3K27M mutation leading to epigenetic dysregulation. Epigenomic analyses of DIPG have shown global loss of repressive chromatin marks accompanied by DNA hypomethylation and altered gene expression. However, most investigations of the epigenetic landscape of DIPG only provide a static view of the epigenome. Such studies are not capable of adequately capturing the regulatory underpinnings of DIPG intratumoral heterogeneity and phenotypic plasticity. To address this, we performed Whole-Genome Bisulfite Sequencing (WGBS) on 23 primary patient DIPG specimens, 4 patient-derived DIPG neurosphere cell lines, and 5 normal controls. To analyze this data set, we applied a novel framework for analysis of DNA methylation variability, called informME analysis, which permits the derivation of comprehensive genome-wide DNA methylation potential energy landscapes that capture intrinsic epigenetic variation. We show that DIPG exhibits a markedly disordered epigenome, with increased stochasticity localizing to key regulatory elements and genes. We demonstrate that epigenetic instability maps onto key genes regulating pluripotency and developmental identity and hypothesize that these changes might enable tumor cells to sample a diverse range of transcriptional programs and phenotypes. Given this, we evaluated the responsiveness of the DIPG epigenetic landscape to pharmacologic modulation. We found that treatment with the DNA hypomethylating agent decitabine produced profound genome-wide demethylation and reduced DNA methylation stochasticity at active enhancers, bivalent promoters, and promoters of key developmental genes. Decitabine treatment also elicited changes in gene expression, including upregulation of genes related to immune signaling. Finally, treatment with DAC sensitized DIPG cells to the effects of histone deacetylase inhibition. This study suggests the application of epigenetic therapies to constrain cellular heterogeneity and plasticity in DIPG.
DIPG-45. ELONGIN B REGULATES H3K27M CHROMATIN INCORPORATION TO PROMOTE MALIGNANCY IN DIFFUSE MIDLINE GLIOMA
Authors: Anastas Jamie , Kebede Adam , Jiao Alan , Mimoso Claudia , Murdaugh Rebecca , Zee Barry , Filbin Mariella , Adelman Karen , Shi Yang
Published: June 2023

Chromatin dysregulation is both a cause and consequence of aberrant RNA Polymerase II (Pol2) transcription in cancer. Some of the most striking examples of chromatin disruption in cancer include somatic mutations in genes encoding histone H3 (H3.3/H3.1K27M) observed in ~80% of diffuse midline glioma (DMG). H3K27M mutant histones act in a dominant manner to disrupt chromatin regulation and Pol2-dependent transcription in DMG. How H3K27M impinges on the Pol2 transcriptional machinery and whether aberrant Pol2 transcription can reciprocally induce chromatin dysregulation in DMG remain open questions. We conducted epigenome-focused CRISPR dropout screens and identified multiple regulators of Pol2 elongation, including Elongin B and C (ELOB/ELOC) as DMG genetic dependencies. Follow-up studies confirm that knockout (KO) of ELOB inhibits DMG proliferation in neurosphere culture and abrogates DMG tumorigenesis in orthotopic xenografts. Additional chromatin profiling studies reveal that ELOB binding sites are enriched in H3K27M mutant histones, suggesting that ELOB works together with H3K27M to promote malignant gene expression in DMG. Indeed, reciprocal knockout studies suggest that while ELOB chromatin binding patterns were not altered by H3K27M KO, ELOB KO significantly reduced H3K27M chromatin incorporation at thousands of genomic loci. Further RNAseq and PROseq analyses reveal that ELOB KO alters Pol2 transcription resulting in the up-regulation of genes associated with neuronal and muscle differentiation and the repression of glial stem cell genes. Together, these findings suggest that H3K27M chromatin binding patterns and aberrant gene regulation in DMG are, in part, dictated by ELOB and the Pol2 elongation machinery. Finally, analyses of patient datasets indicate that ELOB complex genes are overexpressed in high grade glioma and DMG and correlate with decreased patient survival. Collectively, these studies suggest that a functional interaction between ELOB and H3K27M mutant histones induces DMG-specific aberrations in chromatin and gene regulation to drive malignancy.
DIPG-46. TARGETING THE METABOLIC ERK5-PFKFB3 AXIS IN PEDIATRIC DIFFUSE MIDLINE GLIOMA
Authors: Casillo Stephanie , Gatesman Taylor , Chilukuri Akanksha , Jane Esther , Premkumar Daniel , Barber Callie , Halbert Matthew , Cruz Andrea , Mullett Steven , Michel Joshua , Chang Yue-Fang , MichaelRaj Antony , Lieberman Frank , Felker James , Shiva Sruti , Abdullah Kalil , Zinn Pascal , Friedlander Robert , Abel Taylor , Venneti Sriram , Mack Stephen , Wendell Stacy , Pollack Ian , Agnihotri Sameer
Published: June 2023

Diffuse midline glioma is an aggressive brain tumor with a median age at diagnosis of 6.3 years and 5-year survival rate of 2.2%.The defining histone mutation H3K27M precludes docking of a protein responsible for epigenetic modification resulting in erroneously accessible chromatin and subsequent transcription of oncogenic pathways, including the RAS-MERK5-ERK5 signaling cascade. To determine which oncogenic processes are regulated by extracellular signal-regulated kinase 5 (ERK5), gene-set enrichment analysis of patient-derived datasets demonstrated gene networks involved in glycolysis to be enriched with ERK5 expression. In confirmation, loss of ERK5 via shRNA interference reduced cell proliferation and glycolysis in DIPG IV and SF8628 cells. Reintroduction of ERK5 wildtype (WT) into ERK5 knockdown lines rescued cell proliferation and glycolysis, while the addition of ERK5 kinase dead domain (KDD) only partially rescued these survival and metabolic defects. Targeted evaluation of glycolysis enzyme expression via qRT-PCR revealed a direct relationship between ERK5 and proglycolytic enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3). Mechanistically, ERK5 activation of PFKFB3 was mediated by activation of transcriptional factor myocyte enhancer factor 2A (MEF2A) as demonstrated by coimmunoprecipitation and luciferase promoter assays. Expression of PFKFB3 was elevated at both the mRNA and protein level in DMG patient-derived samples. Genetic knockdown of PFKFB3 via shRNA interference resulted in reduced proliferation and glycolysis in DIPG IV and SF8628 cells. Similarly, pharmacologic inhibition of PFKFB3 with small molecule inhibitor PFK-158 capitulated these results. This inhibitor demonstrated blood brain barrier penetrance in silico and extended survival of in vivo mouse models. Multitargeted drug therapy against both ERK5 and PFKFB3 produced a synergetic in vitro response with increased sensitivity of these cells to apoptosis compared to single treatment alone. In conclusion, these results support ERK5 regulation of glycolysis through the critical metabolic effector PFKFB3. Multitargeted drug therapy against this axis represents a therapeutic vulnerability in pediatric diffuse midline glioma.
DIPG-51. ABDOMINAL METASTASES OF DIFFUSE MIDLINE GLIOMA, H3K27-ALTERED WITH A VENTRICULOPERITONEAL SHUNT
Authors: Lazow Margot , Schieffer Kathleen , Palmer Joshua , Salloum Ralph , Widemeyer Michelle , Sribnick Eric , Kumar Shiva Senthil , Umaru Banlanjo , Drissi Rachid , Mardis Elaine , Boué Daniel , Fouladi Maryam , Thomas Diana
Published: June 2023

Extraneural metastases are extremely rare in diffuse midline glioma (DMG), H3K27-altered, despite a tendency toward aggressive local growth and potential neuroaxis dissemination at progression. Ventriculoperitoneal shunt (VPS) placement for cerebrospinal fluid diversion is commonly performed in patients with thalamic tumors and increasingly considered in brainstem disease with developing hydrocephalus. Herein, we present a case of DMG seeding the abdomen presumably via the VPS. This patient was diagnosed at 22 years of age with a bithalamic tumor with extension into the brainstem and cerebellum as well as non-contiguous periventricular spread to the bilateral frontal lobes, with associated hydrocephalus. The patient underwent VPS insertion and biopsy, with pathology consistent with DMG, H3K27-altered. Whole exome sequencing revealed H3-3A and TP53 alterations as well as PDGFRA amplification. Treatment consisted of upfront craniospinal photon irradiation, with subsequent reduction in thalamic disease burden. Adjuvant therapy with an oral PDGFRA inhibitor (avapritinib) was initiated, though discontinued after two weeks due to worsening neurocognitive deficits. The patient presented three months post-completion of radiation, five months from diagnosis, and six weeks following VPS revision with rapidly progressive abdominal distension and altered mental status, with imaging demonstrating omental caking and significant malignant ascites, resulting in shunt malfunction and increased intracranial pressure. With limited therapeutic options, the family decided not to pursue further intervention and the patient died five days later. Autopsy confirmed metastatic disease throughout omentum, in addition to diffuse leptomeningeal dissemination. Comprehensive molecular profiling of diagnostic and post-mortem thalamic and omental tissue is in process to assess temporal as well as spatial genomic heterogeneity, including of metastasis-mediated pathways. In summary, abdominal dissemination of DMG, H3K27-altered is uncommon, but possible, especially in the presence of a VPS. Further research is necessary to determine biologic mechanisms and predictors of extraneural metastases in this disease.
EPEN-04. DEVELOPMENT OF B7-H3-TARGETED CAR T CELL THERAPY FOR EPENDYMOMA
Authors: Mehta Sanya , Houke Haley , Ibanez Jorge , Emanus Erik , Mack Stephen , Krenciute Giedre
Published: June 2023

Targeted treatment options are desperately needed for ependymomas (EPN). Chimeric antigen receptor (CAR) T cells have immense potential to positively transform treatment outcomes; however, little is known regarding antitumor efficacy of CAR T cells against EPNs. We found that B7-H3 is highly expressed on pediatric brain tumor patient-derived orthotopic xenografts from EPN patients, making it a promising target for CAR-T cells. The project’s goal is to develop a safe, effective B7-H3 targeted CAR T cell immunotherapy for EPN. We generated second generation human B7-H3-CAR T cells and examined their anti-EPN cytolytic activity, expansion, and cytokine production. We found that B7-H3-CAR T cells had potent in vitro antitumor activity against all EPN cell lines tested (1425, ST1, CPITT, ST2, EPI, L6SJ). In repeated-stimulation assays, CAR T cells expanded 7-10 times, and up to one million-fold when co-cultured with EPN cells. Interestingly, while the EPN cells were found to secrete high levels of C-C motif chemokine ligand 2 (CCL2) which is consistent with published data, our Multiplex analysis of co-culture supernatants shows that CCL2 production increased up to 10-fold when EPN cells were co-cultured with CAR T cells. Finally, we demonstrate that B7-H3-CAR T cells had antitumor activity in a supratentorial-EPN xenograft mouse model (1425 cell line) without apparent toxicities, although 4 out of 12 tumors re-lapsed. Recurrent tumor analysis is underway. Together, our data shows establishment of a clinically relevant model to study resistance to CAR T cell therapy in EPN, and preliminary mechanistic insight into CAR T cell persistence and modulation through CCL2 signaling. Given that little is known about the function of CCL2 and its receptor, C-C chemokine receptor type 2 (CCR2) in EPNs or CAR T cells, future work will focus on defining these biological mechanisms, enabling us to develop improvements to B7-H3-CAR T cells for EPN.