bluuebunny/crossref_metadata_2025 huggingface dataset:
Prospects for the detection of very-high-energy pulsars with LHAASO and SWGO
Authors: Hu Quan , Zhang Yi , Duan Kaikai , Zeng Houdun
Published: June 2024

Pulsations from the Crab pulsar have been detected by the MAGIC telescopes at energies up to 1.5 TeV, and the pulsed emission from the Vela pulsar was detected by H.E.S.S., reaching tens of TeV. These discoveries, along with the proposed additional emission due to inverse Compton scattering at TeV energies, lead us to consider suitable candidates for detection with current and future extensive air show (EAS) experiments at very-high-energy (VHE; 0.1$-$100 TeV) ranges. Leveraging energy spectrum data from pulsars as observed by Fermi and Imaging Atmospheric Cherenkov Telescopes (IACTs) and considering the sensitivities of both LHAASO and SWGO, this study evaluates their detectability and estimates the time required for their significant detection. Our results indicate that LHAASO could detect the Crab’s pulsed signal within six years, while SWGO might detect Vela’s signal within one year. Observations of the most energetic Fermi pulsars with EAS experiments will provide insight into the nature of VHE pulsar emissions, helping us to clarify the primary characteristics of VHE pulsars.
African Liveliness as a Secular Moral Theory: Problems and Prospects
Authors: Lougheed Kirk
Published: June 2024

An important belief in African Traditional Religion holds that everything, both animate and inanimate objects, are imbued with an imperceptible energy known as life force. Since life force is the greatest value, it is the grounds of morality. However, it is undertheorized in contemporary African ethics, with work on personhood and harmonious relationships taking centerstage. I seek to fill this gap in the literature by further developing an entirely secular and naturalistic moral theory of life force that avoids metaphysical controversies and is known as liveliness, which was first gestured at by Thaddeus Metz (2012, 2022). I demonstrate that while a series of objections that Metz levels against liveliness affect teleological versions, they do not apply with equal force to deontological versions. Liveliness, particularly deontological versions, ought to be considered as a contender for the best African moral theory alongside those that focus on personhood or harmonious relationships.
ATRT-04. RETROSPECTIVE ANALYSIS OF 271 RELAPSED AND REFRACTORY ATYPICAL TERATOID RHABDOID TUMORS – COMBING DATA FROM INTERNATIONAL COHORTS IN A COLLABORATIVE EFFORT
Authors: Steinbügl Mona , Rosenberg Tom , Desai Kavita , Govender Dinisha , Liu Anthony Pak Yin , André Nicolas , O’Hare Patricia , Nysom Karsten , Bourdeaut Franck , Fisher Michael J , Margol Ashley , Reddy Alyssa T , Frühwald Michael C
Published: June 2024

BACKGROUND

Relapse or refractory (r/r) disease is common in atypical teratoid rhabdoid tumors (ATRT), yet little is known about clinical patterns, prognostic factors, and outcomes beyond individual case reports. Large representative cohorts are missing, impeding the interpretation and design of clinical trials for r/r ATRT.

METHODS

We retrospectively collected data on r/r ATRT from centers in the US, Europe, Hong Kong, and Australia, including patients previously enrolled in clinical trials (e.g., COG ACNS0333, DFCI 02-294) or the prospective EU-RHAB registry. Inclusion criteria were relapse (recurrence after complete remission (CR)) or progression (tumor growth or new metastasis without previous CR) following at least one course of chemotherapy.

RESULTS

271 patients were analyzed; median age was 16 months (m) at diagnosis (0-233). Molecular subgroup status was available in n=118. Relapse (44%) or progression (54%) occurred after a median of 8m. Only 34% of events were localized at the primary tumor site; distant metastasis only (31%) and combined events (31%) were more common. Salvage treatment was multimodal with systemic pharmacotherapy (n=176), surgery (n=71), high-dose chemotherapy (n=19), and/or radiotherapy (n=110). Targeted treatment included epigenetically targeted drugs (n=45), alisertib (n=11), immunotherapy (n=10) and metronomic therapy (n=45). 1-year overall survival (OS) following an event was 29.6±2.8%. Log-rank test suggested subgroup status as a prognostic factor. (TYR vs. non-TYR: 30 vs. 21w OS, p< 0.05; MYC vs non-MYC: 14 vs. 25w OS, p<0.05). OS was significantly inferior after progression compared to relapse (19 vs. 33w, p<0.05) and in patients with rhabdoid tumor predisposition syndrome (18 vs. 25w, p<0.05).

CONCLUSION

Our data confirm the poor prognosis of r/r ATRT. However, intense multimodal treatment is feasible, and molecular characteristics are potentially clinically relevant. Results from this analysis offer a robust foundation for prospective clinical trials and therapeutic algorithms for r/r ATRT.
ATRT-10. ANTI-B7-H3 CHIMERIC ANTIGEN RECEPTOR NK CELLS SHOW ANTIGEN SPECIFIC CYTOTOXICITY AGAINST ATYPICAL TERATOID/ RHABDOID TUMORSIN VITRO ANDIN VIVO
Authors: Choe Jun , Chakravarti Sachiv , Holl Natalie , Rahnama Ruyan , Zinsky Megan , Jones Danielle G , Vorri Stamatia , Modi Arjun , Raabe Eric H , Bonifant Challice L
Published: June 2024

BACKGROUND

Atypical teratoid/rhabdoid tumors (AT/RTs) are the most common malignant CNS tumor in infants. AT/RT patients have a 5-year overall survival rate of ~35% and high rates of relapse, emphasizing a dire need for new safe and effective therapies. These therapy-resistant tumors frequently overexpress cell surface molecule B7-H3 (CD276). CAR-NK cells have several advantages over CAR-T cells. NK cells can be obtained from healthy donors and produced as an “off-the-shelf” product. NK cells also have a lower risk of inflammatory toxicity and graft-versus-host disease compared to T-cells when transferred across the HLA barrier.

METHODS

We have designed a library of variable affinity B7-H3-targeted CARs, produced γ-retroviral vector, and used this for generation of B7-H3 CAR-NK cells. We verified B7-H3 expression in a panel of AT/RT cell lines, and further engineered firefly luciferase expressing AT/RT (CHLA06.ffLuc, BT12.ffLuc, BT37.ffLuc) as well as a CHLA06-derived B7-H3 knockout. We developed an orthotopic CHLA06.ffLuc xenograft model. We tested CAR-NK cell functionality using in vitro co-culture and cytotoxicity assays. In vivo study was performed in our xenograft with intratumoral delivery of CAR-NK cells.

RESULTS

B7-H3 targeted CAR-NK cells demonstrate target-specific cytotoxicity when compared to untransduced NK cells (36.8±12.5% vs. 72.4±24.2% at effector:target ratio of 1:1, n=3). CRISPR/Cas9 mediated knockout of B7-H3 in target cells abolished the difference in CAR vs. no-CAR NK-mediated target killing. When delivered intracranially to CHLA-06 orthotopic xenograft bearing mice, B7-H3 CAR NK cells eliminate tumor cells and prolong survival, whereas unmodified NK cells did not (log-ranked median survival = 20 vs. 84 days, p<0.0001).

CONCLUSIONS

Targeting AT/RTs with an anti-B7-H3 CAR-NK cell therapy may provide a safe and effective treatment for patients who have extremely limited therapeutic options. Direct intracranial injections of cell therapies into pediatric patients is currently being explored in clinical trials.
ATRT-11. IRS-III: LONG-TERM FOLLOW-UP SHOWS FAVORABLE OUTCOMES AND DURABLE RESPONSES FOR LOCALIZED ATYPICAL TERATOID RHABDOID TUMOR (ATRT)
Authors: Desai Kavita , Rosenberg Tom , Power Phoebe , Manoharan Neevika , Nagabushan Sumanth , Green-Murphy Audrey , Ziegler David S , Li Yimei , Fisher Michael J , Chi Susan
Published: June 2024

BACKGROUND

IRS-III-based chemotherapy is a long-standing treatment approach for ATRT, which mostly affects infants under the age of 3. We provide long-term outcomes from three high-volume pediatric centers, including a subgroup of patients treated with “moderately-delayed” radiation therapy (RT).

METHODS

We performed a retrospective analysis of 60 patients treated between 1999-2021. Patients at Boston and Sydney Children’s Hospitals received per-protocol early chemoradiation during induction cycles 3-4, while patients at Children’s Hospital of Philadelphia received moderately-delayed RT with temozolomide post 6 induction cycles. Demographic, clinical and outcome data were collected.

RESULTS

Median age at diagnosis was 2.3 years (range:0.5-19.5) with median follow-up 2.7 years (range:0.1-15.5); however, 20/60 patients were followed > 5 years (median 10.4, range:5.1-15.5). Thirty-six patients (60%) underwent gross or near-total resection; 14 (23%) had metastatic disease. Seventeen (28%) did not receive RT due to progression, toxicity, or provider discretion; 27 (45%) received focal and 17 (28%) craniospinal RT. For the entire cohort, 5- and 10-year PFS were both 30% (95%CI: 19-42). OS were 38% (95%CI: 27-51) and 31% (95%CI: 19-43), respectively. For patients with localized disease, 5-year PFS and OS were 38% (95%CI: 24-52) and 45% (95%CI: 30-56), respectively. Patients with metastatic disease had 5-year PFS and OS of 0% and 19% (95%CI: 3-43), with no long-term survivors. In multivariate analysis, RT was a statistically significant prognostic factor. However, treatment field (focal vs. CSI), RT timing (early vs. moderately-delayed), patient age, resection extent, or metastatic status were not significant.

CONCLUSIONS

Our results suggest that IRS-III should remain a standard of care approach for localized ATRT, based on the favorable survival outcomes with the longest follow up of any published ATRT regimen to date. In addition, it highlights the importance of RT for localized disease and proposes it can be given after induction without compromising outcomes, reducing treatment-related toxicity.
ATRT-12. EXPLORING FGFR INHIBITION AND COMBINATION THERAPIES FOR ATYPICAL TERATOID/RHABDOID TUMORS
Authors: Senfter Daniel , Freund Julia , Mager Leah , Bruckner Katharina , Stepien Natalia , Mayr Lisa , Jaunecker Carola N , Laemmerer Anna , Kirchhofer Dominik , Kuess Peter , Eckert Franziska , Dorfer Christian , Kool Marcel , Haberler Christine , Berger Walter , Lötsch-Gojo Daniela , Madlener Sibylle , Gojo Johannes
Published: June 2024

BACKGROUND

Atypical teratoid/rhabdoid tumors (ATRTs) are aggressive pediatric brain neoplasms characterized by an inactivation of the SWI/SNF chromatin remodeling complex members SMARCB1 or SMARCA4. Based on epigenetic profiling ATRTs can be divided into four different molecular subgroups. Despite improvements in treatment strategies, the prognosis for ATRT patients remains dismal. The FGF/FGFR signaling pathway plays a crucial role in many physiological processes, including embryonic development, tissue repair, angiogenesis. Dysregulation of the signaling axis is driving tumorigenesis. Targeted therapeutic approaches, particularly FGFR inhibitors, have demonstrated potential in enhancing treatment outcomes for various tumors, including pediatric brain tumors.

METHODS

We used bulk and single-cell RNA sequencing (scRNA-seq) data to examine the expression patterns of FGF family members in ATRTs. Subsequently, we conducted in vitro analysis on a panel of FGFR inhibitors and combination treatments.

RESULTS

Transcriptomic analysis of more than 130 ATRT tissues samples, revealed a widespread expression of FGFR1 and FGFR2 across all ATRT subtypes. Notably, FGFR1 displayed distinctly elevated expression in ATRT-SHH, surpassing levels seen in other ATRT subtypes and brain tumor types. Utilizing scRNA-seq data of murine ATRT models, we elucidated an autocrine FGFR signaling loop. To assess the therapeutic feasibility of targeting FGFR, we evaluated a panel of FGFR inhibitors, currently in clinical development, across 10 in house established patient-derived cell models (6 ATRT-MYC, 3 ATRT-SHH, 1 ATRT-TYR), revealing sensitivity in a nanomolar to a low-micromolar range. We further explored combination therapies, demonstrating that Erdafitinib, the most effective inhibitor when combined with Abemaciclib and radiation, exhibited enhanced synergistic effects in 2D as well as in 3D tumoroid models. Investigations towards testing these combinations in an organoid co-culture system, along with in vivo models are ongoing.

CONCLUSIONS

This study emphasizes the prospect of combining FGFR inhibition with radiation and CDK4/6 inhibition as a therapeutic target for ATRTs.
ATRT-13. NOVEL ACYLFULVENE LP-184 SYNERGIZES WITH RUCAPARIB TO KILL AT/RT CELLS
Authors: Tindall Abigail , Kwon Abby , Eberhart Charles , Raabe Eric
Published: June 2024

BACKGROUND

Atypical Teratoid Rhabdoid Tumor (AT/RT) is a pediatric brain cancer with survival rates of less than 40%. Illudins are a novel class of DNA-damaging alkylating agents. LP-184, an investigational synthetic acylfulvene analog currently in a first-in-human Phase 1 trial, exhibits enhanced ability to penetrate the brain and damage DNA in tumor cells. We hypothesized that LP-184 would synergize with PARP inhibitors such as rucaparib which inhibit DNA repair. The combination of these therapies could be a promising treatment option for AT/RT.

METHODS

We tested LP-184 against the AT/RT cell lines BT37, CHLA06, CHLA05, and CHLA266. Cell viability assays were conducted by flow cytometry. Immunofluorescence was performed to visualize CC3 and BrdU. Western blots were performed to determine c-PARP and p-RB protein levels. Synergy experiments were performed using cell growth inhibition as the readout and quantified using the SynergyFinder online computational tool.

RESULTS

LP-184 suppressed AT/RT proliferation at nanomolar concentrations as measured by BrdU immunofluorescence and pRB western blots (BrdU BT37 p=0.0001, CHLA06 p=0.0001, CHLA05 p=0.033 50 nM concentration of LP-184 compared to DMSO control). Furthermore, LP-184 showed strong synergy with the PARP inhibitor rucaparib. Viable cell count was reduced by as much as 80% in combination compared to DMSO control (BT37 p=0.0001, CHLA06 p=0.0002, CHLA05 p=0.0077). Combination therapy decreased proliferation as measured by immunofluorescence and confirmed by pRB western blots (BrdU BT37 p=0.0004, CHLA06 p=0.0033, CHLA05 p=0.0154 compared to DMSO control). LP-184 and rucaparib induced apoptosis as measured by cleaved caspase 3 (CC3) and cPARP western blots (BT37 p=0.0002, CHLA06 p=0.0117, CHLA05 p=0.0001 %CC3+ compared to control). Survival studies in vivo are underway to test single agent and combination therapies of LP-184 and rucaparib in AT/RT.

CONCLUSION

LP-184 and rucaparib together could provide a compelling clinical option for patients with this poor-prognosis brain tumor.
ATRT-15. COMBINING THE PI3K INHIBITOR PAXALISIB WITH NUCLEOSIDE ANALOG GEMCITABINE TO IMPROVE SURVIVAL OF ATYPICAL TERATOID/RHABDOID TUMORS
Authors: Findlay Tyler , Malebranche Kristen , Geethadevi Anupa , Eberhart Charles , Rubens Jeffrey , Raabe Eric
Published: June 2024

BACKGROUND

Atypical teratoid/rhabdoid tumors (ATRT) have a dismal overall survival. Targeting the mTORC1/2 pathway kills ATRT tumor cells and increases the survival of mice bearing orthotopic xenografts. Paxalisib is a brain penetrant PI3K inhibitor that is in pediatric clinical trials for diffuse midline glioma. Paxalisib activates the integrated stress response (ISR) in ATRT. Consistent high-level activation of the ISR leads to cell death. We hypothesize paxalisib will synergize with the DNA-damaging agent gemcitabine, which also triggers the ISR, to over-activate this pathway and drive ATRT apoptosis.

METHODS

We analyzed ISR gene expression following mTOR inhibition via RNA-seq. Children’s Brain Tumor Network (CBTN) provided comparative data on ISR genes in ATRT and other pediatric brain tumors. Paxalisib/gemcitabine effects were evaluated through cell-based assays, western blot for ISR markers, and survival in three murine models.

RESULTS

ATRT have high baseline expression of ISR genes (CBTN: ATF4, eIF2α), and mTOR inhibition leads to activation of ISR genes (ATF4, CHOP, PPP1R15A, p<0.05). Paxalisib monotherapy significantly extends median survival in murine models compared to vehicle controls (CHLA-06: 40 to 54 days, p=0.001; BT-12: 21 to 35 days, p=0.05). Paxalisib/gemcitabine therapy synergized to slow cell growth and induce cell death (SynergyFinder BLISS score in five ATRT cell lines). Combination therapy leads to ISR activation (western blot: p-eIF2α, ATF4, CHOP). Combination slowed tumor growth (bioluminescent imaging) and led to significant extension of survival in orthotopic xenograft models (CHLA-06: 22 to 82.5 days; BT-37 56-day vehicle median survival while undefined combination survival). A third model is ongoing and showing similar results.

CONCLUSIONS

Paxalisib/gemcitabine therapy shows potential for targeting ATRT by over-activating the ISR. Our findings prompted the Pediatric Neuro-Oncology Consortium to consider this combination for inclusion in an upcoming clinical trial targeting relapsed/refractory ATRT, offering a novel approach to treat this aggressive tumor.
BIOM-09. TOWARDS CLINICAL IMPLEMENTATION OF LIQUID BIOPSY ANALYSIS FOR PAEDIATRIC BRAIN TUMOUR PATIENTS – A PAN-EUROPEAN EFFORT FOR STANDARDIZATION
Authors: Simon Nike , Maass Kendra K , Pokorná Petra , Stepien Natalia , Rettenmeier Johanna , Saijonmaa Oskar , Fischer Tom T , Senfter Daniel , Madlener Sibylle , Giraud Géraldine , Tham Emma , Scarpini Cinzia G , Murray Matthew J , Hulleman Esther , Clifford Steven C , Pfister Stefan M , Pajtler Kristian W , Gojo Johannes
Published: June 2024

BACKGROUND

Liquid biopsies (LBs) allow for analysis of tumour-derived molecules, such as cell-free DNA (cfDNA) and microRNAs (miRNAs), complementing cancer diagnostics, therapy monitoring, and minimal residual disease detection. While circulation-based LB has benefit for extracranial tumour entities, peripheral blood has not historically been a reliable source for diagnosis and disease-monitoring in brain tumours. For these tumours, cerebrospinal fluid (CSF) analysis is better suited for detection despite being a more invasive procedure. However, standardized protocols for sample collection and pre-analytical parameters for these LBs currently are limited.

AIM

We aim to establish an evidence-based gold standard protocol for cfDNA and miRNA analyses from CSF in paediatric brain tumour patients. In addition to higher compliance in trial-related CSF sampling, this initiative seeks to facilitate identification of clinically relevant indications and time-points for collection, thereby paving the way for well-informed, routine CSF molecular diagnostics.

METHODS AND RESULTS

We have initiated the Liquid Biopsy Working Group within the framework of the International Society of Paediatric Oncology Europe Brain Tumour Group (SIOPE-BTG). Available literature on LB in brain tumours was critically assessed regarding pre-analytical parameters, downstream analyses and LB assay performance. To directly evaluate confounding by pre-analytical factors, we experimentally compared the impact of CSF sampling sites, storage conditions, and different pre-processing protocols. cfDNA and miRNA yields, purity, and the fraction of tumour-derived material were selected as read-outs and correlated with tumour tissue information. To prepare for clinical translation, we consulted clinical paediatric brain tumour trial coordinators to identify major bottlenecks for CSF sampling in routine clinical practice. In addition, clinical practitioners and patient/ parent representatives have been consulted to comprehensively represent the perspectives and needs of all stakeholders. Together, results of this collaborative effort will be fundamental to the successful clinical integration of LBs to improve the future management of paediatric brain tumour patients.
CNSC-01. UNDERSTANDING PEDIATRIC BRAIN TUMOR CHEMOTHERAPY INDUCED LONG-TERM DEFICITS IN HIGH-ORDER NEUROCOGNITIVE AND SENSORIMOTOR FUNCTION
Authors: Singh Anand K , Bertrand Renae , Mahalingam Rajasekaran , Zimbwa Shungu , Kasm Khalil A Ahmad , Pan Yuan
Published: June 2024

BACKGROUND

Because of major advancements in cancer treatment especially chemotherapy, 85% of children with cancer are predicted to survive for 5 years or more. However, chemotherapy can cause long-term health problems when childhood cancer survivors enter adulthood (known as late effects). The neurocognitive features of these late effects (chemobrain) include trouble in concentrating, memorizing, and decreased processing speed, and results in lower IQ and academic achievement, poor hand-eye coordination, and slower development over time. Despite such a negative impact on the quality of life of cancer-surviving children, the mechanism is poorly understood and there is no FDA-approved drug to prevent or cure these side effects.

METHODS

To gain a better understanding of the mechanism underlying chemotherapy-induced cognitive impairments, we developed a pre-clinical model using carboplatin in juvenile mice to study long-term neurological defects. We have tested the capacity of different doses of carboplatin and its long-term effect on cognitive and sensorimotor function and performed single nuclear RNA sequencing (snRNAseq) of the hippocampus.

RESULTS

Our preliminary data demonstrated dose-dependent deficits in executive and sensorimotor function 7-9 weeks after carboplatin administration in the mice of both sexes. snRNAseq of the hippocampus showed changes in the glial cell number as well as genes associated with oxidative phosphorylation and neurodegeneration at early and late time points.

CONCLUSIONS

This study established a preclinical model that can be leveraged to mechanistically understand the long-term neurocognitive side effects of brain tumor chemotherapy during childhood. Future studies will aim to identify potential targets to prevent and/or treat the neurotoxic effects of cancer treatment in pediatric patients.
CP-03. EXTRACELLULAR MATRIX REMODELING REVEALS NON-CELL AUTONOMOUS TUMOR FORMATION MECHANISM IN ADAMANTINOMATOUS CRANIOPHARYNGIOMAS
Authors: Jeang John A , Jomaa Danny , Novikov Dana , Tsai Jessica W , Apps John R , Manshaei Saba , Prince Eric , Hankinson Todd C , Martinez-Barbera Juan-Pedro , Bandopadhayay Pratiti
Published: June 2024

Adamantinomatous Craniopharyngioma (ACP) is a rare pituitary tumor of the sellar region, with a bimodal presentation pattern in children and middle-aged adults. ACPs are primarily driven by a mutation in CTNNB1 that prevents beta-catenin from degrading properly, resulting in accumulation in the nuclei of epithelial whorl-like structures sometimes referred to as cluster cells. Clinical management is challenging due to the location of the tumor, such that complete surgical resection is often not possible so radiation therapy, which can lead to high morbidity, is also used. Greater insight into these tumors can help develop less damaging treatment strategies. In this analysis we have employed single-cell RNA sequencing technology to examine seven pediatric human ACPs (28594 cells). Using consensus non-negative matrix factorization, and traditional marker genes, we have partitioned our dataset into several cell types including cluster cells, palisading epithelial cells, microglia, T-cells, B-cells, plasma cells, and fibroblasts. Though cluster cells themselves do not actively proliferate, we believe the complex inter-cellular signaling is responsible for tumor formation. We propose a model in which malignant fibroblasts form from the existing epithelium and remodel the extracellular matrix (ECM) creating a stiffened tumor microenvironment. To support this claim we show activation markers suggesting myofibroblast differentiation, the expression of EMT signatures indicating a transformation from epithelial to fibroblast, and RNA velocity analysis that demonstrates lineage tracing. We believe that the remodeling of the ECM is a wound healing response influenced by TGF-beta, SPP1, and other signaling pathways. Our analysis of ACPs reveals the role of the tumor microenvironment in the formation of these tumors.
CP-04. UNVEILING THE MYSTERIES OF PEDIATRIC ADAMANTINOMATOUS CRANIOPHARYNGIOMA - INSIGHTS FROM DIAGNOSIS TO ADVANCED THERAPEUTICS
Authors: Shatara Margaret , Abdelbaki Mohamed S
Published: June 2024

BACKGROUND

Adamantinomatous Craniopharyngiomas (ACPs) are rare tumors arising from the remnants of the craniopharyngeal duct epithelium. Their diagnosis poses unique challenges, often resulting in delayed identification due to their slow growth and nonspecific symptoms. Additionally, the prolonged overall survival (OS) is overshadowed by a substantial recurrence rate and late consequences, posing significant challenges, and impairing the patient’s quality of life (QoL). Recent advancements in understanding ACP’s genomic, transcriptomic, and proteomic aspects underscore the need for innovative treatments to mitigate these long-term consequences.

METHODS

We conducted an in-depth literature review, focusing on large clinical trials and major publications in ACP to provide a comprehensive perspective on the challenges in the diagnosis, treatment, and molecular aspects of pediatric ACP.

RESULTS

ACP’s clinical presentation involves increased intracranial pressure, endocrine abnormalities, and visual impairments. Despite their low-grade classification, ACPs exhibit aggressive clinical behavior, often invading or adhering to adjacent tissues, particularly critical neurovascular structures. Imaging techniques, including CT and MRI with a focus on hypothalamic involvement, play a crucial role in diagnosis, pre-operative evaluation, and surgical planning. Multidisciplinary approaches are essential for developing tailored treatment strategies. Neurosurgical management and radiotherapy, particularly proton therapy, are the primary therapeutic modalities. The molecular landscape reveals intricate and complex mechanisms and include the upregulation of the Wingless (WNT) signaling pathway driven by CTNNB1 mutations, along with involvement of inflammatory, programmed cell death, and the MAPK/ERK pathways. Ongoing trials exploring targeted therapies may play a pivotal role in refining treatment strategies and improving outcomes.

CONCLUSIONS

Navigating the complexities of ACP requires a multidisciplinary approach. Advances in diagnostics, surgical strategies, and targeted therapies, informed by molecular insights, offer promising avenues for improving outcomes and QoL. Ongoing collaborative efforts and participation in clinical trials are vital for refining treatment strategies and advancing the understanding of this challenging condition.
CP-13. MRI-DERIVED NUCHAL SKINFOLD THICKNESS AS AN INDEX OF BODY COMPOSITION IN CHILDHOOD-ONSET CRANIOPHARYNGIOMA
Authors: Vijay Eshaa , Crowley Julia , Fisher Michael J , Kline Cassie , Shekdar Karuna , McCormack Shana E
Published: June 2024

BACKGROUND

Survivors of childhood craniopharyngioma often develop obesity. Body mass index (BMI) is an imperfect estimate of adiposity. Nuchal skinfold thickness (NST) is a measure of upper body adiposity obtainable from routine surveillance brain MRIs. Our objective was to evaluate whether NST adds more information than BMI alone regarding excess adiposity in survivors of childhood craniopharyngioma.

METHODS

This was a single-site, retrospective review of children (all ages) diagnosed with craniopharyngioma between 2008 and 2020 with data at baseline, and 6 (±2) and 12 (±2) months follow-up (2008-2020). NST was measured on a mid-sagittal T1-weighted MRI image, on the line crossing the anterior and posterior margins of the foramen magnum. BMI Z-scores (BMI-Z) were calculated using extended CDC references. Mixed effects regression assessed change in NST related to time from diagnosis and BMI-Z, accounting for age and sex.

RESULTS

Thirty-two patients met criteria (female, n=9 [28%]; median age 8.3y [range, 2.1-15.5] at diagnosis). Mean BMI Z-scores were 0.82 (SD 1.38) at diagnosis, 1.44 (1.07) at 6 months (p=0.004 vs. diagnosis), and 1.40 at 12 months (p=0.01 vs. diagnosis). Median nuchal thickness was 7.1 mm (IQR 5.8, 9.5) at diagnosis, 9.7 mm (IQR 7.8, 10.7) at 6 months (p=0.001 vs. diagnosis), and 10.1 mm (IQR 8.1, 12.6) at 12 months (p=0.0001 vs. diagnosis). As expected, nuchal thickness positively associated with BMI-Z (β, 1.3, p<0.001). Even after accounting for age, sex, and change in BMI-Z, NST was higher at 12 months as compared to diagnosis (β, 1.8, p=0.004).

CONCLUSION

BMI-Z and NST increase over time in children with craniopharyngioma. Increases in NST are not explained by increases in BMI-Z alone, suggesting that NST reflects an additional dimension of body composition. Next, we will evaluate how including NST along with BMI improves cardiometabolic risk prediction in childhood craniopharyngioma.

FUNDING

Finamore Family Research Fund.
DIPG-05. CHARACTERIZATION OF THE EFFECTS OF H3K27M VARIANTS ON THE DNA-DAMAGE RESPONSE AND TUMOR EVOLUTION IN DIFFUSE MIDLINE GLIOMA
Authors: Poux Nicolas , Kebede Adam F , Beroukhim Rameen , Bandopadhayay Pratiti
Published: June 2024

Diffuse midline gliomas (DMGs) are universally-fatal pediatric brain tumors driven by K27M alterations in histone 3 (H3K27M). Histone 3 is encoded by several variants, including the canonical H3.1, and H3.3 which replaces H3.1 at transcriptionally active and repetitive genomic regions. Both H3.3K27M and H3.1K27M are present as driver events in DMGs and recent single-cell-RNA and whole-genome sequencing experiments have demonstrated that they define distinct subsets of disease, with varying secondary genetic alterations and different gene-expression patterns. The cause of the divergence in routes of tumor evolution between these subsets remains an open question. Previous work by our group has shown that H3.3K27M DMGs show greater genomic instability than H3.1K27M tumors – with a greater number and higher complexity of genomic structural variants resulting from errors in double-stranded DNA break repair. This raises the possibility that histone variants differentially influence the generation of, or response to, DNA breaks. Here we present an early-stage project that aims to investigate whether H3K27M variants are sufficient to produce differences in genomic instability and in directing the path of tumor evolution. Using isogenic cell-line models expressing H3.1K27M or H3.3K27M, we aim to characterize whether H3K27M variants produce varying levels of replicative stress and P53 activation, leading to varying selective pressures for P53 loss. In turn, we seek to demonstrate that loss of P53 produces a greater growth advantage in H3.3K27M cells, and that P53 loss leads to increased tolerance of genomic instability in DMG models. Together, these experiments seek to provide new insight on the mechanisms of divergence between H3.1K27M and H3.3K27M-driven DMGs, and a better understanding of the sources of genomic instability in DMGs. Given that ionizing radiation remains the only approved treatment modality for DMGs, a greater understanding of DMG response to DNA-damage is critical to improving therapeutic outcomes.
DIPG-13. TIM-3 TARGETED APTAMER IN COMBINATION WITH LOCO-REGIONAL RADIOTHERAPY IMPROVES SURVIVAL BY MODULATING THE IMMUNE INFILTRATION IN DIFFUSE MIDLINE GLIOMA MODELS
Authors: Ausejo-Mauleon Iker , de la Nava Daniel , Martinez-Velez Naiara , Nuin Sara , Morales Sandra , Palacios-Alonso Daniel , Pastor Fernando , Alonso Marta M
Published: June 2024

BACKGROUND

Diffuse midline gliomas (DMG) are the most aggressive pediatric brain tumors. Their meager survival has not changed in the last decades emphasizing the urgent need for effective treatments. TIM-3 has emerged as a new target expressed in multiple immune cell types, regulating adaptive and innate immunity. In this work, we used an aptamer against TIM-3 to modify the tumor microenvironment and enhance the antitumor effect.

METHODS

For in vivo experiments, DMG murine cells were injected orthotopically into the pons of mice using a screw-guided system. The aptamer was administered intracranially (380pmol) on day 5 with the same system and three times intravenous (320pmol/mouse) 8-11-14 days after tumor implantation. In the radiotherapy experiments, 6Gy was given on day 7. Tumor and immune populations were analyzed by flow cytometry.

RESULTS

TIM-3 aptamer as monotherapy increases immune infiltration and elicits a specific immune response with a modest tendency to improve overall survival. Interestingly, we observed that radiotherapy, DMG standard of care, significantly induced TIM-3 expression in tumor and immune cells in the tumor microenvironment (TME). The combination of TIM-3 aptamer with radiotherapy increased the overall survival (3-fold), led to long-term survivors (30-50%), and generated immune memory in three different glioma models. Importantly, combination treatment significantly increases the infiltration of immune cells (3-fold) in the TME compared with the control groups. Radiotherapy and TIM-3 Apt treatment significantly increased the number and proliferative state of microglia, dendritic, NK, CD4, and CD8 T-cells. Interestingly, TIM-3 aptamer decreased the number and proliferative state of Tregs increasing the pro-inflammatory ratio of CD8: Tregs in the TME compared to non-treated groups after radiotherapy.

CONCLUSIONS

In conclusion, we provide evidence that combining radiotherapy with a TIM-3 aptamer increases overall survival, leads to the expansion of myeloid and T-cells in the TME, and generates immune memory in DMG models.
DIPG-61. ARGININE DEPRIVATION USING ADI-PEG20 IMPROVES SURVIVAL IN A SYNGENEIC DIFFUSE MIDLINE GLIOMA MOUSE MODEL
Authors: Chattenton Dani , Brooks Molly , Perryman Richard , Mussa Hamida , Chatziathanasiadou Maria , Syed Nelofer
Published: June 2024

BACKGROUND

Diffuse midline glioma (DMG-H3K27) presents a significant challenge in paediatric oncology, with a <10% two-year survival rate despite standard palliative radiotherapy. Tumour infiltration behind the blood-brain barrier hampers drug delivery, contributing to clinical trial failures. ADI-PEG20 exploits tumour metabolic vulnerabilities: lack of argininosuccinate synthetase and reliability on extracellular arginine for proliferation. This study investigates ADI-PEG20’s efficacy in a syngeneic DMG mouse model.

METHODS

Twenty C57BL/6J mice were intracranially injected with a DMG cell line (H1H3BK27M, DNp53, PDGFRAD642V, Acvr1G328V) and monitored via bioluminescence imaging from day 7. Weekly treatments began on day 10, comprising ADI-PEG20 (5 I.U.) alone, ADI-PEG20 with concurrent radiation (2 Gy), radiation alone, or saline (0.9%), with each group comprising n=5. Radiation was administered 24 hours post-drug treatment. Bioluminescence imaging was conducted twice weekly, with mice culled upon symptom onset. Immunohistochemistry was performed on brain tissue.

RESULTS

The combination and ADI-PEG20 monotherapy cohorts exhibited comparable median survival rates, both surpassing those of the radiation-only and saline groups, with the latter exhibiting the lowest median survival. A significant disparity in survival curves was observed overall (p<0.0001), confirmed by log-rank (Mantel-Cox) test. Pairwise comparisons revealed significant differences in survival curves between the combination and radiation-only (p=0.0066), ADI-PEG20 monotherapy and radiation-only (p=0.0018), and ADI-PEG20 monotherapy and saline (p=0.0062) groups. Minimal divergence in IVIS signal intensity was noted across groups. Histological examination via H&E staining demonstrated marked tumour regression in mice treated with ADI-PEG20 ± radiation, contrasting with the persistent tumour mass evident in the radiation-only and saline cohorts, alongside discernible heterogeneity in cellular phenotypes within the ADI-PEG20 ± groups.

CONCLUSIONS

In conclusion, ADI-PEG20 shows promise as a therapeutic strategy for DMG, offering a significant survival advantage over radiation and saline. Ongoing efforts will elucidate its mechanistic underpinnings, explore its efficacy across diverse DMG models, and assess synergistic interactions with immune-based therapies.
DIPG-67. RE-IRRADIATION PRACTICES AND OUTCOMES IN PATIENTS WITH DIPG/DMG: A REPORT FROM THE INTERNATIONAL DIPG REGISTRY
Authors: Pillay-Smiley Natasha , Webster Aaron , Lane Adam , Hawkins Cynthia , Hassall Tim , Leach James , Jones Blaise , Dorris Kathleen , Hansford Jordan R , Zaghloul Mohamed , Cheng Sylvia , Hummel Trent R , Hoffman Lindsey M , Warren Katherine E
Published: June 2024

BACKGROUND

Given that radiation therapy is the only treatment modality demonstrated to result in any clinical benefit for children with DIPG, re-irradiation therapy has been explored as a treatment option for progressive DIPG. Several studies suggest re-irradiation is feasible, and may lengthen survival for children with progressive DIPG. However, any re-irradiation benefits are unclear and no standard of care (dose, fractionation, volume, timing, clinical status) has been defined. The aims of this study are to evaluate re-radiation therapy practices for children with progressive DIPG/DMG and to define a historical cohort of children with DIPG/DMG who have received re-radiation (re-XRT) for progressive DIPG/DMG.

METHODS

Data was extracted from the International DIPG Registry, and analyzed with descriptive statistics.

RESULTS

Of 1214 patients in the iDIPG Registry, 113 receiving re-XRT. Patients were diagnosed between 2002-2022, with the majority of patients diagnosed over the last decade. Of those 113 patients with specified data, at re-irradiation, n=68 (60%) received photon and n= 4 (4%) were treated with proton radiation. The median dose at re-XRT was 25 Gy (20-30 IQR) in 10 fractions (10-14 IQR). Time between initial XRT and re-XRT was 41.5 weeks (29.5-54 weeks). OS from diagnosis was 18 months (range, 15-23 mo); OS from re-XRT was 6 months (range, 4-10 mo).

CONCLUSIONS

Re-radiation therapy for children with DIPG/DMG is becoming a more common practice and appears to have OS benefit, with post-progression OS of 6 mo comparing favorably to historical data of 2.3 mo. [Cooney T et al, Neuro Oncol 2017] Efforts are underway to define patient selection and tolerability. Data extraction from the SIOPE DIPG/DMG Registry is also ongoing; data from both registries will be collated and uniformly presented.
DIPG-68. FLAG-003, A NOVEL, DUAL-ACTION THERAPEUTIC, DEMONSTRATES IN-VITRO ACTIVITY AGAINST DIFFUSE INTRINSIC PONTINE GLIOMA (DIPG)
Authors: Bhatia Sonam , Quinn Thomas , Ligon Keith L , Bandopadhayay Pratiti , Warren Katherine
Published: June 2024

BACKGROUND

FLAG-003 is a novel, rationally-designed, CNS-penetrant, dual-acting agent that inhibits receptor tyrosine kinase activity and microtubule polymerization. Preclinical studies in glioblastoma (GBM) demonstrated decreased cell viability, reduced tumor volumes, decreased microvessel density, and increased survival. Remarkably, using an orthotopic DIPG model, all mice treated with FLAG-003 at 275 mg/day/orally displayed tumor regression, tumor reduction and increased survival. Given the significant preclinical activity against DIPG, as well as the known heterogeneity of DIPG, we evaluated the efficacy of FLAG-003 in vitro against a panel of DIPG cell lines.

METHODS

Eight DIPG cell lines hosted at the Center for Patient Derived Models (CPDM) were selected based on genomic and growth characteristics. Cells were plated on 384-well plates; 24 hours after plating, cells were dosed with 1nM to 50uM (12 step log curve) FLAG-003. Three technical replicates were performed per step. Controls consisted of positive kill control Staurosporine, negative growth control of 0.5% DMSO, or no DMSO for baseline growth. ONC201, a small molecule antagonist of DRD2/3 currently in clinical trials for DIPG, was used as a comparator. We also evaluated two GBM patient-derived models.

RESULTS

FLAG-003 demonstrated efficacy in all DIPG and GBM cell lines tested with IC50 less than 100nM. FLAG-003 was more potent compared to ONC201 in all models evaluated.

CONCLUSIONS

Single agent FLAG-003 demonstrated activity against a panel of DIPG cell lines. As next steps, we are exploring the efficacy of this drug in orthotopic DIPG PDX models. Continued development of FLAG-003 as a potential therapeutic candidate for DIPG patients is warranted and underway.
DIPG-74. TARGETING TRANSCRIPTIONAL DYSREGULATION IN DMG THROUGH CDK9 AND HDAC INHIBITOR COMBINATION THERAPY
Authors: Eberl Brittany R , Murdaugh Rebecca L , Nnyagu Adanze N , Richard Rosemary U , Deneen Benjamin , Yu Kwanha , Anastas Jamie N
Published: June 2024

BACKGROUND

With no successful treatment options available, diffuse midline glioma (DMG) are fatal brain tumors with a median survival of ∼12 months. DMG are characterized by transcriptional dysregulation induced by the H3K27M driver mutations. Since these histone mutations cannot yet be directly targeted pharmacologically, our goal is to identify druggable targets of aberrant transcription in DMG. Previous studies identified RNA polymerase 2 (Pol2)-targeting cyclin-dependent kinase 9 inhibitors (CDK9i) and histone deacetylase inhibitors (HDACi) as potential DMG therapeutics, and CDK9i and HDACi are under investigation in ongoing glioma clinical trials. This study aims to develop CDK9i+HDACi combination therapies for DMG.

METHODS

We determined the consequences of CDK9i+HDACi combination treatment in DMG using in vitro dose curve analyses, orthotopic xenograft models, and molecular profiling through immunofluorescence imaging, Western blotting, flow cytometry and RNA-seq analysis.

RESULTS

We find that CDK9i+HDACi combination therapy synergistically reduces DMG growth in vitro and alters DMG protein post-translational modifications associated with gene regulation by reducing phos-Pol2-Ser2 and increasing histone acetylation. Further RNA-seq analysis identified unique transcriptional changes induced by CDK9i+HDACi, including the downregulation of genes associated with mitochondrial function, cell division, and DNA repair. In line with these gene expression changes, additional studies suggest that CDK9i+HDACi treatment induces DNA damage and cell cycle defects. Finally, preliminary pre-clinical studies using an orthotopic DMG xenograft model reveal that CDK9i and HDACi treatment reduces DMG tumor growth as measured by bioluminescent imaging.

CONCLUSIONS

Together, these studies suggest that CDK9i and HDACi co-treatment alters DMG protein modifications and gene expression leading to cell cycle defects, DNA damage, and reduced tumor growth. In view of the proposed synergistic role of CDK9i and HDACi in DMG, additional ongoing studies are examining if this combination may represent a novel approach for the treatment of DMG.
DIPG-75. PHARMACOLOGICAL INHIBITION OF LSD1/KDM1A IN DIFFUSE MIDLINE GLIOMA MODELS AND IMPACT ON KINASE SIGNALING
Authors: Hernandez Faith A , Stitzlein Lea M , Nam Deokhwa , Adams Jack , McCabe Caitlin , Monje Michelle , Waranecki Piotr , Hulleman Esther , Becher Oren , Chandra Joya
Published: June 2024

BACKGROUND

High grade gliomas (HGGs) in both adults and children confer poor prognosis, with median survival rates under two years post-diagnosis. Diffuse midline gliomas (DMG) are a subset of HGG characterized by histone mutations, typically occurring in children. Genetic alterations in chromatin modifiers and receptor tyrosine kinases (RTKs) are seen in both adult and pediatric glioblastoma, however the interplay between these pathways requires further investigation to design therapeutic strategies. Our past work has evaluated KDM1A/ LSD1 (Lysine-Specific Demethylase 1) inhibition through gene silencing and small molecules; here we assessed crosstalk between LSD1 and kinase signaling networks to uncover potential compensatory resistance mechanisms using clinically relevant pharmacological inhibitors of LSD1.

METHODS

RNA-Seq and GSEA in high grade glioma cells bearing LSD1 knockdown were evaluated for kinase signaling pathway enrichment. A panel of DMG lines (SU-DIPGIV (MDM4, ACVR1), SU-DIPGVI (TP53), VUMC-DIPG10 (NF1, MYCN), and SU-DIPGXIII and DMG data sets were probed for LSD1 expression, activity and kinase expression and treated with pharmacological inhibitors of LSD1 in vitro and in vivo.

RESULTS

Pharmacological inhibition of LSD1 using clinically relevant agents revealed IC50s in the micromolar range across DMG lines. DMG lines varied with respect to LSD1 expression and baseline activation of ERK and AKT pathways. With LSD1 inhibition at subtoxic doses, increased phospho-ERK/ERK and phospho-AKT/AKT was noted in several DMG models and co-inhibition of these pathways suggests improved efficacy.

CONCLUSIONS

Our data reveals that LSD1 inhibition causes an increase in kinase signaling at subtoxic doses which may alter drug response. These results urge the assessment of combination treatments with kinase inhibitors and additional in vivo analysis, which are currently underway.
DIPG-82. RADIOSENSITIZATION WITH RAD52 INHIBITION IN DIFFUSE MIDLINE GLIOMA
Authors: Uchida Eita , Ishi Yukitomo , Watanabe Jun , Abdala-Valencia Hiam , Singer Benjamin , Gadd Samantha , Hashizume Rintaro
Published: June 2024

BACKGROUND

Diffuse midline glioma (DMG) is one of the most devastating childhood cancers that limited response to radiation therapy (RT). There is a critical need for new therapeutics that enhance the radiation effect. We, therefore, tested the hypothesis that targeting RAD52 activity sensitizes the radiation response of DMG.

METHODS

Genome-wide CRISPR/Cas9 screening was performed to identify the potential therapeutic target. RAD52 inhibition was used by shRNA-mediated RAD52 depletion and treatment with RAD52 inhibitor, D-I03. The protein expression, cell proliferation, DNA damage marker expression, DNA repair pathway, and transcriptional alteration were analyzed by western blotting, MTS assay, colony formation assay, immunocytochemistry, DNA repair pathway assay, and RNA sequencing. Mice with DMG patient-derived xenograft (PDX) models were treated with RAD52 inhibitor alone or combination with RT.

RESULTS

Genome-wide CRISPR/Cas9 screening identified RAD52 as a potential therapeutic target in DMG cells. RAD52 inhibition suppressed DMG cell proliferation. Importantly, RAD52 inhibition in combination with RT further increased the radiosensitivity of DMG cells. Immunocytochemistry of DNA double-strand breaks (DSB) marker γH2AX and repair marker 53BP1 showed that RAD52 inhibition sustained DNA damage with high levels of γH2AX at 24 hours following radiation while the level of 53BPI was decreased, thereby inhibiting DNA DSB repair. Western blotting also revealed that RAD52 inhibition causes a sustained level of phosphorylated Rad50 and γH2AX in irradiated DIPG cells over 24 hours. DNA repair assay showed that RAD52 inhibition suppressed homologous recombination DNA repair pathway. RNA sequencing showed that RAD52 inhibition downregulated genes associated with the DNA repair pathway. Finally, the combination therapy of RAD52 inhibitor and RT further suppressed tumor growth and increased survival of mice bearing DMG PDXs, outperforming either monotherapy.

CONCLUSIONS

these results highlight RAD52 inhibition as a potential radiosensitization and provide a rationale for developing combination therapy with radiation in the treatment of DMG.