bluuebunny/crossref_metadata_2025_split huggingface dataset:
HGG-12. Rapid PTEFb-dependent transcriptional reorganization underpins the glioma adaptive response to radiotherapy
Authors: Walker Faye , Sobral Lays Martin , Danis Etienne , Sanford Bridget , Balakrishnan Ilango , Wang Dong , Pierce Angela , Karam Sana , Serkova Natalie , Foreman Nicholas , Venkataraman Sujatha , Dowell Robin , Vibhakar Rajeev , Dahl Nathan 
Published: June 2022

Abstract
BACKGROUND: Dynamic regulation of gene expression is fundamental for cellular adaptation to exogenous stressors. PTEFb-mediated promoter proximal pause-release of Pol II is a conserved regulatory mechanism for synchronous transcriptional induction best described in response to heat shock, but this pro-survival role has not been examined in the applied context of cancer therapy. DESIGN/METHOD: In order to examine the dynamics of chromatin reorganization following radiotherapy, we performed a combination of ChIP-, ATAC-, and RNA-seq in model systems of diffuse intrinsic pontine glioma (DIPG) and other pediatric high-grade gliomas (pHGG) following IR exposure. We interrogated IR-induced gene expression in the presence or absence of PTEFb blockade, including both mechanistic and functional consequences of concurrent inhibition or genetic depletion. We utilized culture models with live cell imaging to assess the therapeutic synergy of PTEFb inhibition with IR, as well as the therapeutic index of this intervention relative to normal controls. Finally, we employed orthotopic models of pHGG treated with conformal radiotherapy and CNS-penetrant PTEFb inhibitors in order to assess tolerability and anti-tumor effect in vivo. RESULTS: Rapid genome-wide redistribution of active chromatin features and PTEFb facilitates Pol II pause-release to drive nascent transcriptional induction within hours of exposure to therapeutic ionizing radiation. Concurrent inhibition of PTEFb imparts a transcription elongation defect, abrogating canonical adaptive programs such as DNA damage repair and cell cycle regulation. This combination demonstrates a potent, synergistic therapeutic potential agnostic of glioma subtype, leading to a marked induction of tumor cell apoptosis and prolongation of xenograft survival. CONCLUSION: These studies reveal a central role for PTEFb underpinning the early adaptive response to radiotherapy, opening new avenues for combinatorial treatment in these lethal malignancies.
HGG-17. Novel Fusion in Congenital Brainstem Diffuse High-Grade Glioma
Authors: Norris Gregory , Donson Andrew , Milgrom Sarah , Gaskell Alisa , Willard Nicholas , Foreman Nicholas , Gilani Ahmed , Dahl Nathan 
Published: June 2022

Abstract
BACKGROUND: Infant-type hemispheric glioma, previously termed infantile glioblastoma multiforme, is a rare infantile neoplasm with improved survival and distinct molecular features when compared to other pediatric and adult-type high-grade glioma. Infant-type high-grade gliomas are typically located in the cerebral hemispheres and are characterized by ALK, ROS1, MET, and NTRK fusions. Typical brainstem gliomas (diffuse midline glioma, H3 K27-altered or diffuse intrinsic pontine glioma) are comparatively rare in this age group. As a result, the biology of brainstem congenital high-grade gliomas is poorly described. RESULTS: A 3 month old female who initially presented with failure to thrive had an apneic event and was found to have an infiltrative mass in the medulla with expansion into the pons and cervical spine on magnetic resonance imaging. She underwent surgical biopsy with pathology revealing diffuse high-grade glioma, WHO grade 4. Next generation sequencing showed no alterations to H3F3A, IDH, or fusions involving BRAF, ALK, ROS1, MET, or NTRK. Whole-transcriptome sequencing revealed a novel fusion of PDGFRB:APOBEC3C. She received chemotherapy with 2 cycles of carboplatin/etoposide and 2 cycles of carboplatin/etoposide/imatinib before having disease progression. She then underwent palliative radiation (35 Gy in 10 fractions) with near complete regression of her disease. Surprisingly, our patient has not had any progression of disease or new lesions now two years from her last therapy. CONCLUSION: Congenital high-grade glioma is a rare, unique entity that greatly differs from its adult and childhood counterparts. Here, we discuss a previously-unreported fusion of PDGFB:APOBEC3C in a patient with congenital brainstem diffuse high-grade glioma with a favorable clinical course. This highlights the importance of routine molecular characterization, both to better understand the complex biology of this rare disease and to guide prognosis and clinical decision making for individual patients and families.
HGG-24. NTRK-rearranged infantile gliomas of suprasellar/ optic pathway origin
Authors: Lazow Margot A , Mathew Mariam , Salloum Ralph , Rodriguez Diana P , Leonard Jeffrey , Chi Susan , Thomas Diana , Cottrell Catherine , Fouladi Maryam , Boué Daniel R 
Published: June 2022

Abstract
BACKGROUND: Oncogenic fusions involving neurotrophic tyrosine receptor kinase (NTRK) have been identified across cancer types and represent potential therapeutic targets given availability of TRK inhibitors. Gliomas harboring NTRK fusions have been described most commonly in infants with high-grade histology and hemispheric tumor location, though there is emerging evidence suggesting clinical, histopathologic, and molecular heterogeneity. Herein, we present two cases of NTRK-rearranged suprasellar/ optic pathway gliomas. CASE DESCRIPTIONS: The first patient was diagnosed at 6 months old with an extensive suprasellar/ optic pathway tumor, treated with carboplatin/ vincristine, which initially responded but subsequently progressed. A biopsy was then performed, with pathology consistent with infiltrating piloid astrocytoma with anaplastic features (elevated mitoses and Ki-67 index); a BCAN-NTRK1 fusion was identified by RT-PCR and confirmed by Sanger sequencing. After further disease progression on vinblastine monotherapy, this patient began treatment with entrectinib (NCT02650401), with favorable clinical and radiographic responses thus far. The second patient was diagnosed with a large suprasellar/ optic pathway tumor at 3 years old, and underwent upfront partial resection, revealing similar infiltrating piloid/pilocytic astrocytoma with anaplastic features (elevated mitoses and Ki-67 index). A diagnosis of “midline” infantile high-grade glioma (HGG) was also considered, as with the former case. Sequencing demonstrated a SOX10-NTRK3 rearrangement, resulting in an integrated diagnosis of NTRK-fused infantile HGG, for which the patient recently started treatment with larotrectinib (NCT04655404). Both patients’ fusions retain the entire kinase domain of respective NTRK partners, supporting oncogenicity, and neither tumor harbored additional somatic pathogenic variants (both lacked BRAF alterations). Methylation profiling did not confidently classify either tumor. CONCLUSIONS: NTRK-rearranged gliomas may present with primary suprasellar/ optic pathway involvement in infants. Given the potential to offer targeted therapy, testing for the presence of NTRK fusions should be strongly considered for infantile gliomas in any location, including midline, and across the histologic spectrum.
HGG-25. Targeting KLF5 reduces tumorigenic phenotype in a murine glioblastoma (GBM) model
Authors: Abou-Antoun Tamara , Kfoury Najla , Yang Lihua , Warrington Nicole , Chen Xuhua , Reiss India , Wilkinson Michael , Mitra Robi , Rubin Josh 
Published: June 2022

Abstract
Sex differences are evident in the incidence, therapeutic response and survival of patients with various cancers including the most common, aggressive and incurable GBM. We generated a murine GBM model of male and female astrocytes with dual loss of NF1 and P53 that yielded a sex-biased transformation of the astrocytes with male cells being significantly more tumorigenic and therapeutically resistant compared to female cells. In our current work, we aimed to delineate the molecular mechanisms driving this sex-biased tumorigenic phenotype in order to deliver therapies that are more effective to patients with GBM. We examined the inhibition of KLF5 on tumorigenic phenotypes using cellular bio-functional assays. We used barcoded transposon calling cards to determine the genomic localization of KLF5 and the differentially induced gene expression in male versus female GBM cells. Chemical inhibition or shRNA knock-down of KLF5 significantly reduced proliferation, migration, clonogenic stem-cell frequency and survival, but increase apoptosis in male and female GBM cells. Interestingly, male, but not female, GBM cells exhibited an increased migratory phenotype after radiation that inhibition of KLF5 significantly reduced. Moreover, KLF5 inhibition significantly reduced the protein expression of tumorigenic PDGFRB, AKT, ERK and the stem marker Sox-2. Transposon calling cards mapped unique KLF5 genomic localization in male versus female GBM cells with significantly differential gene expression profiles between the two. The top genes induced by KLF5 in male cells were primarily affiliated with poorer prognosis and reduced survival, whereas in female cells they were affiliated with better prognosis and improved survival in patients with cancer. Our findings provide a promising exploratory avenue for KLF5 as a therapeutic target in GBM and warrants further investigation in order to delineate the precise molecular mechanisms driving this antitumor response so that targeted therapy would be more effective taking into consideration the sex-differences in patients with GBM.
HGG-32. Durable response to mTOR inhibitor after failing Checkpoint inhibitors in Ultra-Hypermutated High grade glioma in context of CMMRD
Authors: Hegde Kriti , Dahl Christine , Depani Sarita , Hargrave Darren , Oostveen Minou , Aguirregomezcorta Fernando , Jeelani Owase , Aquilina Kristian , Gains Jenny , Ching Yen , Jacues Thomas , Merve Ashirwad , Chalker Jane , Addy Dilys , Ahmed Saira W , Yasin Shireen , Mankad Kshitij , Carney Olivia , Sudhakar Sniya , D'Arco Felice , Loebel Ulrike , Jorgensen Mette 
Published: June 2022

Abstract
BACKGROUND: Paediatric High Grade Gliomas (HGG) have poor outcomes with conventional treatment. HGG in association with constitutional DNA mismatch repair deficiency (CMMRD) are hypermutated and have shown dramatic response to checkpoint inhibitors. Salvage following progression or failure to respond to check point inhibitors has rarely been reported. We describe a successful alternative therapeutic approach targeting the activated pathway (mTOR) in a hypermutated HGG. CASE SUMMARY: A 6-year-old girl presenting with seizures was diagnosed with left frontal lobe HGG with concurrent neck mass (Pilomatrixoma). Presence of synchronous tumours raised the possibility of cancer predisposition; the HGG was hypermutated with germline PMS2 mutation confirming diagnosis of CMMRD. Near total resection was undertaken followed by focal radiotherapy 54 Gy, with 1 cycle of concomitant CCNU. MRI post radiotherapy showed tumour progression. Anti-PDl inhibitor Nivolumab was commenced. CTLA-4 antibody, Ipilimumab was added after 4 cycles of Nivolumab due to poor response. Tumour response was seen, but dual therapy had to be discontinued due to toxicity. The tumour progressed following further single agent Nivolumab. In view of multiple mutations in the mTOR pathway (NF1, PIK3/PTEN, TSC1, TSC2), a mTOR inhibitor, Everolimus was commenced. There was 25% tumour reduction after 4 weeks treatment and further reduction after 6 months. Resection of residual tumour showed necrotic tissue only. There continues to be a sustained response to Everolimus for over 12 months. DISCUSSION: Approximately a third of CMMRD HGG respond to checkpoint inhibitors. For those that don’t, these hypermutated tumours offers the possibility of targeting specific molecular pathways. Response to Everolimus in HGG harbouring mTOR aberrations have been described. To our knowledge this is the first report of successful use of mTOR inhibitor in CMMRD HGG. CONCLUSION: Targeted molecular treatment for patients with CMMRD hypermutated brain tumours should be considered according to the mutated pathways.
HGG-36. Elucidating the role of long non-coding RNAs in pediatric high grade gliomas
Authors: Tsai Jessica W , Dubois Frank P B , Wang Dayle K , Crane Alexander , Condurat Alexandra L , Krug Brian , Brown Adam , Doench John G , Jabado Nada , Bandopadhayay Pratiti 
Published: June 2022

Abstract
BACKGROUND: Genomic and transcriptomic studies have elucidated new insights into the landscape of diffuse intrinsic pontine glioma (DIPG). However, the role of long non-coding RNAs (lncRNAs) has not been explored at depth in these tumors, and there have not been studies focused on how lncRNAs interact with the K27M histone mutation. In a recent analysis of nearly 200 DIPGs and pediatric high-grade gliomas (pHGG), we previously detected a novel, recurring structural variant in the lncRNA CCDC26. This rearrangement occurs in nearly 10% of all DIPGs, and we have furthermore identified alterations in more than 100 lncRNAs in DIPG. METHODS: To identify lncRNAs required for proliferation of patient-derived DIPG cancer cells, we designed two custom genome-scale lncRNA libraries. We generated a genome-scale lncRNA CRISPR-Cas9 knockout pooled library, consisting of 45,766 single guide RNAs (sgRNAs). Additionally, we generated a genome-wide CRISPR interference pooled library consisting of 45,608 sgRNAs, targeting lncRNA transcription start sites (TSS). RESULTS: We utilized in vitro histone-mutant pHGG models as well as edited clones of these models with the K27M mutant corrected in order to compare lncRNA dependencies in these two contexts. We have successfully performed genome-scale CRISPR-Cas9 knockout and CRISPR interference screens targeting lncRNAs in these cell lines, revealing lncRNA dependencies. Candidate dependencies in our CRISPR-Cas9 knockout screen include LOC100507412, LOC105379524, and LINC02193. CONCLUSION: Genome-wide lncRNA CRISPR knock-out and CRISPR interference screens are a novel approach for the unbiased identification of lncRNAs that are required for pediatric high-grade glioma proliferation. Further validation of specific lncRNAs is required, and these lncRNA dependencies represent potential novel therapeutic targets.
HGG-58. SIOPE HGG Working Group approach to obtain consensus on management of paediatric high grade glioma across Europe
Authors: Giraud Géraldine , Szychot Elwira , Kramm Christof , Hargrave Darren , van Vuurden Dannis G ,   SIOPE HGG working group
Published: June 2022

Abstract
BACKGROUND: There is currently no European standard clinical practice on the management of paediatric HGG (pHGG). AIMS: To develop approved clinical recommendations for the management of pHGG reflecting current best practice, with the ultimate aim of improved outcomes. METHODS: An open questions survey was performed to establish the status quo regarding standards of care in pHGG across Europe. National coordinators from 33 countries were invited to participate in the process. RESULTS: 32 out of 33 countries completed the survey. Substantial areas of agreement were reached. All 32 countries agreed that hemispheric pHGG should be treated with radiotherapy and adjuvant chemotherapy after surgical resection. 30/32 (94%) countries proposed initial radiotherapy with concomitant temozolomide where 23/32 (72%) countries recommended a complementary adjuvant chemotherapy (Lomustine, Valproic acid, or Nivolumab). 32 countries agreed H3K27M diffuse midline glioma DMG, including DMG of the pons (DIPG), should be treated with radiotherapy. 10/32 (31%) countries proposed radiotherapy alone at diagnosis. There was no consensus on the role of adjuvant chemotherapy; temozolomide was recommended in 9/32 (28%), while mTOR inhibitor in 7/32 (22%) countries. A biopsy of DIPG was routinely offered in 18/32 (56%) countries, while in 4 countries was considered on an individual basis. Six countries never performed a biopsy. Re-irradiation at the relapse was consensual in 26/32 (81%) countries. Certain areas of divergence were identified. A Delphi method is being employed to reach a general consensus on those areas. CONCLUSION: This two-step approach will help us to set up the European guidelines on the management of pHGG based on the current best standard of care. This approach will also identify areas, which should be the focus of future collaborative studies. Such efforts will ultimately translate into improved patient outcomes.
HGG-59. Pediatric high-grade gliomas and the WHO classification on CNS Tumors - Different perspectives of pediatric neuro-oncologists and neuropathologists in the light of recent updates
Authors: Gielen Gerrit , Baugh Joshua , van Vuurden Dannis , van Zanten Sophie Veldhuijzen , Hargrave Darren , Massimino Maura , Biassoni Veronica , la Madrid Andres Morales , Karremann Michael , Wiese Maria , Thomale Ulrich , Janssens Geert , von Bueren André , Niehusmann Pitt , Gessi Marco , Kwiecien Robert , Bailey Simon , Pietsch Torsten , Andreiuolo Felipe 
Published: June 2022

Abstract
BACKGROUND: The WHO Classification of Tumors of the Central Nervous System has undergone major restructuring following rapid advances in brain tumor genomics and epigenomics. The most significant changes resulted from the introduction of molecularly defined diagnostic criteria in 2016 (revised 4th edition). In 2021 (5th edition), further essential molecular criteria were incorporated. In the present study, we sought to investigate potential differences between specialists in perception of these newly defined molecular subtypes of pediatric high-grade gliomas (pedHGG). METHODS: We designed a 22-question survey studying the impact of the revised 4th edition of the WHO classification on pedHGG. Data were collected and statistically analyzed to capture the spectrum of viewpoints and possible differences among neuro-oncologists and neuropathologists. RESULTS: 465 participants from 53 countries responded, of which 187 pediatric neuro-oncologists (40%), 160 neuropathologists (34%) and 118 experts in other related fields (neurosurgeons, radiotherapists, neuroradiologists and others; 26%). Neuro-oncologists reported having issues with the introduction of new molecular entities, such as the abolishment and renaming of established tumor entities. Neuropathologists did not define these problems to the same extent. However, both groups felt that in the 2016 version, less relevant or insufficient diagnostic definitions were available for pedHGG. Within the 2021 WHO classification, a substantial improvement was perceived regarding the definition of pedHGG entities. However, some issues of high clinical relevance, like the definition of clinical phenotypes such as diffuse intrinsic pontine glioma (DIPG) and gliomatosis cerebri, are yet to be addressed. CONCLUSIONS: Within the WHO classification of pediatric brain tumors, such as high-grade gliomas, rapid changes in nomenclature have been introduced because of substantial improvement in molecular characterization. This study highlights that ongoing cross-talk between advancing classification of pedHGG subtypes and its biological relevance and clinical impact is essential.
IMG-16. Non-invasive metabolic imaging of response to therapy in diffuse midline gliomas
Authors: Batsios Georgios , Taglang Celine , Tran Meryssa , Gillespie Anne Marie , Nazarian Javad , Mueller Sabine , Viswanath Pavithra 
Published: June 2022

Abstract
Diffuse midline gliomas (DMGs) are universally lethal pediatric tumors that are defined by the presence of histone H3K27 alterations. The infiltrative nature and anatomical location of these tumors prohibit surgical resection. Radiotherapy, which is standard of care, does not significantly enhance long-term outcome. Novel therapies are sorely needed for DMG patients. Imipridone drugs ONC201 and ONC206 have demonstrated anti-tumor activity in preclinical cancer models, including DMGs and have shown promise in pilot studies in DMG patients. Successful clinical deployment of imipridones requires the identification of companion imaging biomarkers that report on response to therapy. Magnetic resonance spectroscopy (MRS) is a safe, non-radioactive, non-invasive method of imaging metabolism in vivo. 1H-MRS assesses steady-state metabolite levels and is used in clinics. 2H-MRS following administration of 2H-labeled substrates is a novel, clinically translatable method of imaging metabolic pathway activity. Our results indicate that treatment of SF7761 DMG cells with ONC206 causes a significant reduction in 1H-MRS-detectable lactate, glutamate, glutathione and phosphocholine, pointing to inhibition of glycolysis, oxidative phosphorylation, redox and phosphatidylcholine biosynthesis respectively. Examination of [6,6’-2H]-glucose metabolism using 2H-MRS indicates that lactate production from [6,6’-2H]-glucose is significantly reduced in ONC206-treated SF7761 cells relative to controls. We then investigated the effect of ONC206 on mice bearing orthotopic SF8628 DMG tumors. At day 7 following the treatment onset, at a timepoint when no change in tumor volume can be observed by anatomical imaging, in vivo1H-MRS-detectable lactate and total choline are reduced relative to day 0. Collectively, our studies indicate that imipridones induce alterations in DMG metabolism that can be leveraged for non-invasive 1H- and 2H-MRS-based imaging of response to therapy. By providing clinicians with an early readout of treatment response prior to anatomical changes, our biomarkers will enable early assessment of treatment response and, thereby, clinical translation of these promising therapeutics.
LGG-01. Children with Supratentorial Midline Pilocytic Astrocytomas Exhibit Multiple Progressions and Acquisition of Neurologic Deficits over Time
Authors: Brossier Nicole , Strahle Jennnifer , Cler Samuel , Wallendorf Michael , Gutmann David 
Published: June 2022

Abstract
Pilocytic astrocytomas are the most common solid tumor of childhood and can arise anywhere in the central nervous system, including the posterior fossa (pf-PA), supratentorial midline (sm-PA; including optic pathway, hypothalamus, thalamus), and brainstem (bs-PA). Location (sm, bs) has been previously proposed as a prognostic factor for PA, but is difficult to separate from resection status on multivariate analysis. To overcome this limitation, we assembled a large cohort of children (n = 251) with biopsy-proved PA treated at St. Louis Children’s Hospital from 2003 – 2021 and analyzed outcomes only in patients with subtotal resection (STR; n = 81). We excluded patients with NF1, as NF1-associated gliomas often display a more indolent clinical course than their counterparts. We identified that children with STR sm-PA had a higher likelihood of multiple progressions compared to children with STR bs-PA and pf-PA. This was associated with worsening neurologic deficits over time, consistent with the sm location as a poor prognostic factor. Furthermore, the only children in our cohort with leptomeningeal dissemination or death harbored sm-PAs. Tumors in this location were also associated with an increased likelihood of non-BRAF-fusion genetic alterations and multiple oncogenic mutations. Overall, these data support location as an independent prognostic factor for PA in cases in which a gross-total resection cannot be achieved. Treating neuro-oncologists may thus wish to consider early intervention rather than watch-and-wait strategies at first progression of STR sm-PA. These patients may also benefit from earlier consideration of molecularly targeted therapy.