bluuebunny/crossref_metadata_2025 huggingface dataset:
DIPG-64. UNRAVELING H3K27M INTERACTIONS IN DIFFUSE MIDLINE GLIOMA
Authors: Liapodimitri Athanasia , Lunsford Kayleigh , Tetens Ashley R , Craig-Schwartz Jordyn , Vesuna Farhad , Raman Venu , Koldobskiy Michael A
Published: June 2024

BACKGROUND

Diffuse midline glioma (DMG) harboring the histone H3 K27M mutation, also known as diffuse intrinsic pontine glioma when it occurs in the pons, is a uniformly fatal pediatric brain tumor. We sought to better understand protein-protein interactions of the mutant histone in DMG.

METHODS

To address this, we carried out endogenous co-immunoprecipitation of histone H3 K27M from patient-derived DMG neurosphere cell lines, followed by LC-MS/MS identification of binding partners, and validation of binding by Western Blot. Moving beyond identification, we investigated the functional consequences of these interactions.

RESULTS

We identified putative novel interactors of H3 K27M with notable binding partners including histone chaperones and RNA helicases of the DDX family. We then explored the disruption of downstream effects resulting from this interaction by pharmacologically inhibiting DDX3 using the small molecule inhibitor RK-33, and assessed impact on viability and radiation sensitivity.

CONCLUSIONS

Understanding the protein interactome of the mutant histone can inform alternative ways for targeting DMG, thus enriching the therapeutic toolbox against this aggressive tumor. Functional characterization of binding partners holds the potential to identify novel therapeutic targets that cooperate with H3 K27M. The use of inhibitors targeting these partners could specifically destabilize oncohistone-dependent homeostasis and survival pathways and increase sensitivity to radiation and other therapies.
DIPG-65. NOVEL PATIENT-BASED PHARMACOKINETIC DRUG SCREENING REVEALS GEMCITABINE POTENTIAL IN PEDIATRIC H3K27-ALTERED DIFFUSE MIDLINE GLIOMAS
Authors: Scheffers Liska M , Bianco John , Su Yan , Ringnalda Femke C A , de Lange Elizabeth C M , Huitema Alwin D R , van Vuurden Dannis G
Published: June 2024

BACKGROUND

Pediatric H3K27-altered diffuse midline glioma (DMG) remains incurable, with median overall survival of less than one year. Ineffectiveness of chemotherapy is largely attributed to the blood–brain barrier, hindering drug exposure to the tumor. Current drug sensitivity testing use concentrations vastly different from those attainable in the human brain, with optimal combination, timing, and sequence of drugs remaining underexplored. This study aims to systematically select and validate EMA/FDA approved drugs for effective treatment of DMG, based on human pharmacokinetics.

METHODS

In silico anticancer drug pharmacokinetic (PK) properties were correlated with published DMG cell sensitivities and ranked based on therapeutic index potential. Predictions of brain extracellular fluid time-concentration profiles (AUChumanECF) using plasma PK values of drug candidates, corresponding to human values, were made via physiologically based pharmacokinetic (PBPK) modeling with LeiCNS-PK3.0. In vitro cellular treatment protocols were established that mimic clinically achievable AUChumanECF, to be validated in vivo.

RESULTS

This PBPK drug screening approach revealed gemcitabine as a highly potent drug for DMG therapy for most cell lines tested (AUCplasma/AUCin_vitro = 337.6±233.0). Replicating a phase I clinical study in pediatric leukemia patients (3 weekly courses of 3600 mg/m2), 3 weekly 6-hour exposures to 12.5 µM.h gemcitabine demonstrated up to 99% cell kill as compared to viability at start of treatment. Notably, the cytotoxic effects of gemcitabine became apparent 3-5 days following drug exposure for most cell lines, and would have been missed using conventional drug screening with direct readouts.

CONCLUSIONS

This human PBPK-based drug screening approach underscores the significance of precise timing and dosing in elucidating clinically relevant therapeutic effects, highlighting high-dose gemcitabine as a potential therapy for DMG. Cytotoxic effects of gemcitabine on DMG cell viability are cumulative, and undetected when using conventional drug screening. This underlines the importance of investigating real-life human exposure patterns in the context of DMG.
DIPG-66. MULTIPLEXED IMMUNOFLUORESCENCE MAPPING AND AI MODEL PREDICTION OF TUMOR MICROENVIRONMENT IN DIFFUSE MIDLINE GLIOMAS
Authors: Laternser Sandra , De Micheli Andrea Joseph , Petrovic Antonela , Brüningk Sarah , McDonough Elizabeth , Surrette Christine , Ginty Fiona , Eze Augustine , Dettwiler Susanne , Prutek Fabiola , Lagar Noelia Casares , Morinigo Denise , Bornhorst Miriam , Rushing Elisabeth Jane , Grotzer Michael , Stücklin Ana Sofia Guerreiro , Müller Sabine , Packer Roger , Rodan Marta Maria Alonso , Nazarian Javad
Published: June 2024

BACKGROUND

Diffuse midline glioma (DMG) is a fatal childhood brain cancer with a survival rate of less than one year from diagnosis. Pharmacological approaches and immunotherapy have failed to make a clinical impact. Incomplete understanding of the tumor microenvironment (TME) and tumor associated antigens have contributed to the observed poor prognosis. Therefore, mapping TME is urgently needed.

METHODS

Whole brains were collected at autopsy from 80 pediatric subjects, including patients diagnosed with DMG (n=50), GBM (n=9), non-malignant controls (n=10), ependymoma (n=5), ATRT (n=2). Up to four brain anatomical sites were selected: primary tumor, metastatic and adjacent healthy control sites, and processed for staining with hematoxylin and eosin (H&E). After reviewing the tumor and healthy regions, three punch cores were obtained resulting in a total of 918 core punches and two TMA blocks. Multiplexed immunofluorescence (MxIF) technology was used to probe 43 biomarkers on a single TMA slide, focusing on immune cell types and activation thereof. Clinical data including genomics alterations were obtained from each patient for downstream analyses.

RESULTS

Highest expressed immune markers across all patients were CD8 and CD3 (T-cells), CD68, Iba1 and CD163 (microglia). In DMGs, T-cells were mostly detected and increased in ONC201 and immunotherapy treated patients compared to only immunotherapy treated patients. Analysis of Iba1 confirmed a higher difference in activation in primary tumor compared to metastatic and adjacent healthy tissue, whereas in contrast, CD68 was significantly increased in metastatic sites. Patient plasma and RNA transcriptome analysis confirmed biomarkers and immune related pathways. Further, immune competent murine models were used to validate immune cell infiltration. AI deep learning technology modeling is ongoing now to, in future, be able to predict cell type composition and neighborhoods mapping.

CONCLUSION

We posit that this comprehensive data and characterization of the DMG TME will help to identify biology-informed targeted treatments.
DIPG-70. NQO1 AS A RESISTANCE DRIVER AND THERAPEUTIC TARGET IN DMG
Authors: Lupien Leslie E , Morin Eric , Zhang Daren F , Novikov Dana R , Chacon Madison S , Khuu Nicholas , Keshishian Hasmik , Seidel Olivia , Carr Steven A , Goodale Amy , Persky Nicole S , Root David E , Cusick Margaret , Ligon Keith L , Beroukhim Rameen , Phoenix Timothy M , Rendo Veronica , Bandopadhayay Pratiti
Published: June 2024

p53 pathway reactivation through pharmacologic inhibition of negative regulators was identified as a promising therapeutic strategy for TP53 wild-type (WT) high-grade gliomas, including Diffuse Midline Gliomas (DMGs). Despite widespread theoretical promise, the therapeutic efficacy of MDM2 inhibitors and PPM1D inhibitors as single agents have each been limited by issues, including sub-lethal effects on cancer cells and innate or emerging resistance leading to tumor progression. We carried out a genome-scale CRISPR activating (CRISPRa) screen to identify genes that, when overexpressed, confer resistance to p53 reactivation therapies. NAD(P)H quinone dehydrogenase 1 (NQO1) emerged as a top hit and was confirmed through secondary CRISPRa screens and low-throughput validations as driving a resistance phenotype in TP53 WT DMGs. Our subsequent work has aimed to elucidate the mechanisms through which NQO1 mediates the effects of p53 reactivation therapies, and assess the feasibility and impact of exploiting NQO1 in combination therapies towards a cure.
DIPG-72. CREATION, CHARACTERIZATION AND CATALOGUING NEXT-GENERATION DIPG PATIENT-DERIVED CANCER CELL LINES: THE DIPG C3 PROJECT
Authors: Bhatia Sonam , Quinn Thomas , Chow Kin-Hoe , Vogelzang Jayne , Shetty Aniket , Yerrum Smitha , Monje Michelle , Raabe Eric , Filbin Mariella , Hulleman Esther , Ligon Keith L , Warren Katherine
Published: June 2024

BACKGROUND

Preclinical studies of diffuse intrinsic pontine glioma (DIPG) have increased significantly over the past 15 years due to the development of DIPG disease-specific tools including cell lines and animal models. We now know that DIPG is a molecularly heterogeneous tumor. While >80% of these tumors have H3K27M alterations, partner mutations can vary. Many DIPG cell lines used for pre-clinical assessments of new therapies have not been fully characterized, therefore, comparing preclinical results across studies has been impeded. We sought to Create, Characterize and Catalogue DIPG cell lines and animal models with the aim of expanding contemporary resources and providing a public database for DIPG researchers.

METHODS

Existing DIPG cell lines in the Center for Patient-Derived Models (CPDM) were utilized; additional patient-derived cell lines were created in CPDM, and obtained from collaborators. The assembled collection was characterized by whole genome (WGS) and RNA-sequencing (RNAseq).

RESULTS

To date, we have 21 growth-verified DIPG models with the majority grown as 3D neurospheres in-vitro and capable for long-term culture. Fourteen (14) of these patient-derived models were genomically verified with WGS and RNA-seq platform. Data will be made publicly available to researchers on cBioPortal.

CONCLUSIONS

Systematic characterization and cataloguing of pre-clinical DIPG models is important to allow more stringent comparison across studies and ensure their utility and impact. These DIPG-specific tools can thus be used in applications such as drug discovery and testing.
DIPG-77. SOMATICTP53,PIK3R1, NF1 ORTERT MUTATIONS ARE ASSOCIATED WITH INFERIOR CLINICAL OUTCOME IN H3K27M-ALTERED DIFFUSE MIDLINE GLIOMA
Authors: Nguyen Thien , Lerman Benjamin , Stoller Schuyler , Müller Timothy , Comfort Lion , Lyons Samantha , Holman Lynette , Junior Calixito Hope Lucas , Banerjee Anu , Reddy Alyssa , Gupta Nalin , Whipple Nicholas , Gerber Nicolas , Stuecklin Ana , Areza Esha , Marion Rizo , Knowles Truman , Solomon David , Franson Andrea , Koschmann Carl , Partap Sonia , Monje Michelle , Prolo Laura , Cheshier Samuel , Antony Reuben , Bhatia Aashim , Foster Jessica , LaRiviere Michael , Maule Laura , Carrion Andrea W , Kline Cassie , Bruningk Sarah , Nazarian Javad , Waszak Sebastian M , Mueller Sabine
Published: June 2024

BACKGROUND

H3K27-altered diffuse midline gliomas (DMGs) have poor prognosis with no standard of care therapy beyond radiation (RT). While RT prologues survival, not all patients respond. Prior work has shown somatic TP53 mutations predict radiation resistance, and poorer outcomes. We report on a multi-center retrospective cohort study to identify molecular biomarkers of RT response in DMG patients.

METHODS

We performed retrospective chart reviews of patients with biopsy-proven H3K27M-altered DMG between 2013-2023 from six US medical centers and the DMG Center in Zurich. Patients with tumor genomic sequencing and completion of RT were eligible. Genomic alterations were evaluated for somatic mutations, fusions, and chromosomal instability. Cox proportional hazard models were used to evaluate associations between genomic alterations and survival. Multivariate analysis included all significant variables at P <0.1 in initial analysis, including age at diagnosis, tumor location, TP53 and PIK3R1 alterations.

RESULTS

297 patients (135 female; median age 8.3years; range 0.2-71.4 years) were included. Median progression-free survival (PFS) and overall survival (OS) was 7.6months (95%-CI 6.9-8.6) and 14.0months (95%-CI 12.9-15.7). Univariate analysis identified TP53 or PIK3R1 status to be associated with shorter OS (TP53-mutant 12.5months vs. TP53-wildtype 17.5months; HR=1.5; 95%-CI (1.1-2.0), P=0.005); (PIK3R1-mutant 12.6months vs. PIK3R1-wildtype 14.5months; HR=1.9, 95%-CI (1.1-3.4), P=0.03). Multivariate analysis corroborated TP53 status association with shorter OS (HR=1.5; 95%-CI (1.2-2.0), P=0.003). Subgroup univariate analysis of pontine DMG patients showed reduced OS with TP53, NF1, or TERT mutations (TP53-mutant 11.9months vs. TP53-wildtype 15.2months; HR=1.6; 95%-CI (1.1-2.3), P=0.02); (NF1-mutant 8.4months vs. NF1-wildtype 13.6months; HR=2.3; 95%-CI (1.1-5.0), P=0.03); (TERT-mutant 8.5months vs. TERT-wildtype 13.6months; HR=2.5; 95%-CI (1.1-5.7), P=0.03). Subsequent multivariate analysis corroborated the association of TERT mutations with shorter OS in pontine DMG (HR=2.5; 95%-CI (1.05, 5.9), P=0.03).

CONCLUSIONS

This is one of the largest molecular characterized cohorts of H3K27M-altered DMG patients. DMGs with somatic TP53 or PIK3R1 mutations demonstrate inferior OS. Pontine DMG patients with somatic TP53, NF1 or TERT mutations demonstrate inferior OS.
DIPG-87. TARGETING GENE-REPRESSIVE EPIGENETIC REGULATION TO INDUCE INTERFERON SIGNALING IN DIFFUSE MIDLINE GLIOMA
Authors: Craig-Schwartz Jordyn , Tetens Ashley R , Lunsford Kayleigh , Liapodimitri Athanasia , Koldobskiy Michael A
Published: June 2024

BACKGROUND

Diffuse intrinsic pontine glioma (DIPG) is a fatal pediatric brainstem tumor with no known effective treatment. DIPG is driven by the H3K27M mutant histone, which promotes epigenetic dysregulation, leading to loss of gene-repressive H3K27me3 marks, global DNA hypomethylation, and a distinct gene expression profile. DIPG cells retain histone methylation at histone H3 lysine 9 (H3K9me2/3), suggesting that the tumor may rely on these marks to repress unwanted expression. Our prior work has demonstrated that treatment with the DNA hypomethylating agent decitabine (DAC) elicits expression of cancer-specific antigens and immune activation, including activation of interferon signaling, but modulating gene-repressive H3K9 methylation in DIPG has not been extensively investigated.

METHODS

We treated four primary patient-derived DIPG neurosphere cell lines with BIX01294 and UNC0642, inhibitors of H3K9 methyltransferases G9a/GLP, and analyzed gene expression changes by RNA-sequencing and Western blot. We assessed the effect of combination treatments on these four cell lines with both DAC and either BIX01294 or UNC0642 and evaluated impact on gene expression, innate immune signaling, and interferon pathway activation.

RESULTS

We found that treatment with either of the G9a/GLP inhibitors resulted in the upregulation of genes involved in immune signaling. Given the similarities in the immune signaling response elicited from treatment with DAC and the G9a/GLP inhibitors, we evaluated the effect of combination treatments with both DAC and either BIX01294 or UNC0642. These combinations resulted in an increased induction of genes involved in immune signaling, including STING.

CONCLUSIONS

Pharmacologic inhibition of DNA methylation and histone H3K9 methylation elicits immune activation in DIPG cells. Upregulation of interferon and STING signaling with this combination treatment may be significant in enhancing the immunogenicity of DIPG cells to allow effective immunotherapy.
DIPG-93. OVERALL EXPERIENCE OF TWO PHASE I CLINICAL TRIALS WITH FOCUSED ULTRASOUND-MEDIATED BLOOD BRAIN BARRIER OPENING IN CHILDREN, ADOLESCENTS, AND YOUNG ADULTS WITH PROGRESSIVE DIPG/DMG USING A NEURONAVIGATION-BASED DEVICE
Authors: Szalontay Luca , Fino Jessica , Berg Xander , Lipina Jennifer , Gallitto Matthew , De Santos Genesis Los , Yoh Nina , Gartrell Robyn , Pavisic Jovana , Garvin James , Lignelli Angela , Gomes William , Feldstein Neil , Konofagou Elisa E , Zacharoulis Stergios , Wu Cheng-Chia
Published: June 2024

OBJECTIVES

DIPG/DMG is a fatal brain tumor developing in delicate areas of the brain with a median overall survival of 1 year. The dismal outcome is partly due to the blood-brain barrier (BBB) which poses a major challenge to delivering effective therapeutic agents. Over the past 4 years we opened two Phase I clinical trials using Delsona focused ultrasound (FUS) device developed at Columbia University to treat pediatric and AYA patients with relapsed DMG. In the first study, we delivered FUS with concomitant panobinostat and during the second study we gave oral etoposide. Here we present our experience of delivering neuronavigation based FUS for pediatric patients with progressive DMG.

METHODS

Pediatric and AYA patients with biopsy proven DIPG/DMG at disease progression were enrolled (FUS with oral panobinostat: NCT04804709 and FUS with oral etoposide: NCT05762419). Patients were allowed to have prior therapies, including radiation and reirradiation. FUS was delivered over the course of six or four cycles respectively. MRI was performed to validate BBB-opening and closure.

RESULTS

During the FUS-panobinostat study, we treated 3 patients. The study was closed prematurely when panobinostat was taken off the US market. In the FUS-etoposide study, we have already treated 2 patients (the study is currently open). For the two trials combined, we delivered over twenty-five FUS treatments. Four of the five patients treated had achieved BBB-opening. Two patients in the FUS and panobinostat study showed improvement in their neurological symptoms. The average time for FUS-delivery was approximately 47 minutes. All treatments were performed in the outpatient settings in the Department of Radiation Oncology. Side effects from FUS was limited to one grade 1 dermatological toxicity.

CONCLUSION

FUS-mediated BBB-opening delivered as an outpatient procedure is feasible, to date, in children with relapsed DIPG/DMG. Further studies are needed to assess for efficacy.
DIPG-94. PROTEOMIC AND BIOINFORMATICS ANALYSIS OF THE SURFACEOME AND EXTRACELLULAR MATRIX OF DIFFUSE MIDLINE GLIOMAS
Authors: Thomas Bryce
Published: June 2024

INTRODUCTION

Diffuse midline glioma (DMG) is a universally fatal pediatric brain cancer with a median overall survival of 9-11-months. The extracellular matrix (ECM) plays a significant role in regulating bidirectional communication between glioma cells and the niches of the tumor immune microenvironment (TIME); influencing expression of immunosuppressive cytokines and regulating immune cell infiltrations, all of which contribute to poor outcomes. DMG immunosuppression remains poorly understood but has implications for emerging immunotherapies such as CAR T cells. Using a sucrose gradient plasma membrane purification method coupled with quantitative high-resolution proteomics we have discovered a novel cancer-associated protein termed ‘Protein-J 4 (PJ-4)’. PJ-4 is an important component of the DMG-ECM that we believe contributes to immunosuppression.

METHODS

Expression of PJ-4 was validated by Immunoblotting, flow cytometry and immunofluorescences microscopy. CRISPR/dCas9 gene deletion and amplification of PJ-4 and its transcription factor are current being established using DMG patient-derived cell lines, and syngeneic DIPG models to help elucidate the biological significance of PJ-4 expression.

RESULTS

Immunofluorescences microscopy showed PJ-4’s translocation from the Golgi apparatus to the cell membrane is dependent neurosphere formation, hence the formation of an ECM. Further, PJ-4 demonstrated high affinity with pro-TGF-β and may serve to regulate its bioavailability in the TIME, suggestive of an immunomodulatory role. Immunohistochemistry analysis of our PJ-4, TGF-β and CD45 is currently underway using a constructed tissue microarray of healthy brain tissue samples and over 30 pediatric brain cancers to determine tumor specificity and correlation with immune cell infiltration.

CONCLUSIONS

Resistance to conventional therapies and a poor understanding of the TIME and ECM remains a significant challenge to the development of effective DMG therapies. The identification of PJ-4 as a cancer-associated constituent of the DMG-ECM may help us to develop strategies to that increase DMG response to standard-of-care radiation therapy, novel target agents and immunotherapies.
DEI-04. RACE AND ETHNICITY DIFFERENCES IN TREATMENT-LIMITING TOXICITIES IN PATIENTS TREATED WITH MEK INHIBITORS
Authors: Siegel Benjamin I , Kim AeRang , Bornhorst Miriam A
Published: June 2024

BACKGROUND

MEK inhibitor (MEKi) therapies are used to treat pediatric low grade glioma (pLGG) and plexiform neurofibroma (PN). The toxicity profile reported in clinical trials have been favorable, but samples have been demographically homogeneous. In this study, we evaluate differences in treatment-limiting toxicities by race and ethnicity.

METHODS

This is a single-institution, retrospective study of patients treated with MEKi on the Sprint (NIH plexiform) trial or off-study for pLGG or PN from 2014 to 2023. Patient data was abstracted from clinical records. Treatment-limiting toxicity was defined as temporary hold, dose reduction, or discontinuation due to toxicity.

RESULTS

Fifty-eight evaluable patients received MEKi for PN (N=40) or pLGG (N=18), 5 of whom received multiple agents. Selumetinib was used in 44 cases, trametinib in 16, and binimetinib in 3. Median age was 11.0 years (IQR 7.7-14.5) and 37(64%) were male. Twenty-nine (50%) patients identified as White, 15(26%) Black, 6(10%) Asian, 4 (7%) Hispanic, and 4(7%) other/declined. Treatment-limiting toxicity occurred in 27(47%). Each demographic group had a similar rate of treatment-limiting toxicities; 52%(n=15) of White, 40%(n=6) of Black, 66%(n=4) of Asian patients, and 50%(n=2) of Hispanic patients. The most prevalent treatment-limiting toxicity was skin-related (N=10; 6 White, 1 Black, 2 Asian, 1 Hispanic) and included rash, paronychia, and impetigo. Other recurring toxicities were gastrointestinal (N=6, 5 White, 1 Black), edema (N=4, 1 White, 1 Black, 1 Asian, 1 Hispanic), cardiac (N=2, 1 White, 1 Black), and weight gain/loss (N=4, 2 White, 2 Asian).

CONCLUSIONS

Frequencies of treatment-limiting toxicities were similar across race and ethnicity. Dermatologic and gastrointestinal toxicity were more commonly seen in White patients relative to other adverse events. Findings should be interpreted with caution due to sample size, but support future efforts to understand demographic differences in MEKi toxicity.
DEI-05. ASSESSING HOUSEHOLD MATERIAL HARDSHIP IN CHILDREN WITH CENTRAL NERVOUS SYSTEM (CNS) TUMORS
Authors: Coven Scott L , Tran Yvette H , Park Seho , Mendonça Eneida A
Published: June 2024

BACKGROUND

Household material hardship (HMH) is defined as unmet basic needs including food, heat, housing, or transportation. Researchers have documented higher rates of poor nutrition, injury, infectious disease, and hospitalization in healthy children living in families with household material hardship. Furthermore, targeted interventions exist to modify these health outcomes. However, little is known regarding the relationship between social determinants of health and their impact on overall and quality of survival for children with brain or spinal cord tumors. The current available information is based upon retrospective and secondary data sources, often limited to basic socioeconomic factors such as race and ethnicity. The objective was to describe the change in household material hardship through patient reported outcome measures from baseline to six-months and explore the association between social determinants of health, including prospective household material hardship data, and clinical outcomes among children with brain and spinal cord tumors.

METHODS

We aimed to enroll 150 patients with a brain or spinal cord tumors who were followed by the Pediatric Neuro-Oncology Program at Riley Hospital for Children at IU Health. These participants were approached during their routinely scheduled clinic visits by a member of the study team. Written or verbal consent/assent was obtained, and their data was transcribed into a REDCap™ database.

RESULTS

To date, we have enrolled 118 children onto this study, with 35/76 participants completing their six-month follow-up survey. In line with Kira Bona’s previous work, we have found that around 30% acknowledged one positive domain of household material hardship. Additionally, we have found that almost 40% of our cohort fall below the 200% Federal Poverty Level, which is often considered a cutpoint for lower socioeconomic status.

CONCLUSIONS

We have shown that collecting prospective patient reported sociodemographic information is feasible in a busy clinical setting.
TRLS-10. CLINICAL TRIAL IN PROGRESS - CONNECT2007: PHASE I/II STUDY OF LUTATHERA IN PATIENTS WITH RECURRENT AND/OR PROGRESSIVE HIGH-GRADE CENTRAL NERVOUS SYSTEM (CNS) TUMORS AND MENINGIOMAS THAT DEMONSTRATE UPTAKE ON DOTATATE PET
Authors: Lazow Margot A , Trout Andrew T , Szabo Sara , Fuller Christine , Bobbey Adam , White William , Stanek Joseph , Brady Samuel , Mardis Elaine , Palmer Joshua , Rodriguez Diana P , Reuss Jaime , Brandt Cierra M , Acree Joanna , Harr Anna , Mikael Leonie , Fouladi Maryam , Salloum Ralph
Published: June 2024

BACKGROUND

Somatostatin type-2A receptors (SST2A) regulate cell growth through complex downstream modulation of proliferation and apoptosis signaling, thereby representing a potential therapeutic target. Lutetium (177Lu-DOTATATE), a radionuclide therapy which binds SST2A and delivers local radiation via beta particle emission, gained FDA approval for gastroenteropancreatic neuroendocrine tumors, a disease characterized by SST2A expression. Potential expansion of Lutathera into pediatric neuro-oncology is supported by evidence that medulloblastoma, other embryonal tumors, and meningiomas consistently express membranous SST2A, exhibit corresponding uptake on SST2A-radiolabeled nuclear imaging (DOTATATE PET), and have demonstrated radiographic response to SST2A-targeted therapy, suggesting sufficient CNS penetration to achieve therapeutic benefit.

METHODS

CONNECT2007 (NCT05278208) is an international, multicenter phase I/II study investigating safety and efficacy of Lutathera in children and adults with SST2A-expressing CNS tumors. Patients with recurrent/progressive high-grade CNS tumors and meningiomas can undergo screening, consisting of DOTATATE PET imaging for functional confirmation of SST2A expression, requiring adequate uptake (Krenning score ≥2) by central review. The phase I cohort will enroll patients aged 4-<12 years to determine the pediatric recommended phase II dose (RP2D) following a Rolling Six design, with three potential dose levels, starting at the adult RP2D (200mCi), scaled by body surface area. The phase II cohort will enroll patients aged ≥12 years to assess anti-tumor activity through evaluation of 6-month progression-free survival in medulloblastoma/embryonal tumors (descriptive in other histologies). Lutathera is administered intravenously, with concurrent amino acids for nephroprotection, dosed every 8 weeks for up to 4 cycles. Longitudinal correlative studies include 1) evaluating prevalence, heterogeneity, and clinical, histologic molecular, and radiographic predictors of SST2A expression, 2) characterizing radiation dosimetry of Lutathera in organs at risk of toxicity and within CNS to assess tumor penetration, and 3) identifying imaging and molecular biomarkers of response. Enrollment began in January 2023; both cohorts remain open to accrual.
TRLS-13. MULTI-OMICS AND FUNCTIONAL PRECISION MEDICINE FOR NEWLY DIAGNOSED AND RECURRENT PEDIATRIC CENTRAL NERVOUS SYSTEM TUMORS
Authors: Crawford John R , Lo Yan Yuen , Pagadala Meghana S , Chapman Owen S , Sridhar Sunita , Juarez Edwin F , Tzaridis Theophilos , Chau Lianne Q , Wang Jun , Eisemann Tanja , Masihi Meher Beigi , Chambers Kendall R , Dixit Deobrat , Koubourli Daphne , Larson Jon D , Guidugli Lucia , Hammer Monia , Wong Terence , Abdullaev Zied , Quezado Martha , Martins Timothy J , Reich Michael , Sears Timothy , Hobbs Charlotte , Kingsmore Stephen F , Levy Michael L , Gonda David , Malicki Denise M , Snuderl Matija , Becker Pamela S , Tamayo Pablo , Elster Jennifer D , Aldape Kenneth , Carter Hannah , Paul Megan R , Mesirov Jill P , Chavez Lukas , Wechsler-Reya Robert J
Published: June 2024

BACKGROUND

Comprehensive molecular characterization of pediatric brain tumors has led to a more refined diagnosis. However, the feasibility of performing multi-omic and functional precision medicine approaches using ex-vivo drug screening in the clinical setting is unknown.

METHODS

Patients with newly diagnosed or recurrent central nervous system tumors were enrolled in a feasibility study of multi-omic analysis including whole genome trio germline sequencing, tumor whole exome/RNA sequencing, RNA-based DiSCoVER analysis, methylation profiling, immunogenic potential analysis, and ex-vivo drug screening utilizing a customized panel of 175 FDA approved/investigational drugs. Findings were presented at a multidisciplinary molecular neuro-oncology tumor board.

RESULTS

Eighteen patients (9 female; average age 9.4 years; 12 newly diagnosed, 6 with recurrent disease; 5 high grade gliomas, 4 ependymomas, 4 embryonal tumors, 3 low grade gliomas, 2 others) were enrolled between 2020-2022. Whole genome germline testing (N=18) was normal in half of patients (pathogenic germline mutations in 3 patients, variants of unknown significance in 6 patients). Ex-vivo drug screening results (N=14) varied among patients, however sub-micromolar efficacy was commonly observed for proteosome inhibitors, HDAC inhibitors, and topoisomerase II inhibitors. Average time from surgery to receipt of finalized results varied across platforms (drug screening 5.7 days, whole exome/RNA sequencing 14.8 days, whole genome germline 10.6 days, methylation 21 days). Fifteen patients had a modification in diagnosis and 4 patients had a change in tumor classification. Multi-omic and functional precision medicine results alone or in combination led to changes in management in 50% of patients (Tumor Molecular Sequencing 6/18, Ex-Vivo Drug Screening 4/14, RNA DiSCoVER Analysis 2/15, Methylation 1/14).

CONCLUSION

Our studies demonstrate the feasibility of timely ex-vivo drug screening and multi-omic analysis and show that these data may lead to changes in patient diagnosis/management. These findings are the basis of an ongoing trial for recurrent medulloblastoma (NCT05057702).
TRLS-16. RESULTS FROM SJDAWN: A ST JUDE CHILDREN’S RESEARCH HOSPITAL PHASE 1 STUDY EVALUATING MOLECULARLY DRIVEN DOUBLET THERAPIES FOR ALL CHILDREN WITH REFRACTORY OR RECURRENT CENTRAL NERVOUS SYSTEM (CNS) MALIGNANT NEOPLASMS AND YOUNG ADULTS WITH SHH MEDULLOBLASTOMA
Authors: Robinson Giles W , Orr Brent A , Dhanda Sandeep K , Lin Tong , Sabin Noah D , Han Katie , Kostecka Anna , Onar-Thomas Arzu , Roussel Martine F , Stewart Clinton , Gajjar Amar , Northcott Paul A
Published: June 2024

BACKGROUND

Pediatric CNS tumors have recurring molecular aberrations that modulate the cell cycle. We hypothesized that ribociclib, a brain-penetrant CDK4/6 inhibitor, given in doublet combinations could benefit patients with CNS malignancies. SJDAWN (NCT03434262) was launched to determine the recommended phase 2 dose (RP2D), safety, pharmacokinetics, and early efficacy of doublets.

METHODS

Patients >1 and <40 years with recurrent/refractory CNS malignancy were stratified into 3 strata. Escalating dose-levels in 28-day cycles were evaluated in each stratum by rolling-6 design with an expansion cohort at the highest tolerated dose-level. RP2D was declared if ≤3 dose-limiting toxicities (DLTs) occurred in 12 patients. Stratum A evaluated ribociclib/gemcitabine in group3/group4 (Grp3/4) MB and ependymoma (EPN). Stratum B evaluated ribociclib/trametinib in malignancies not eligible for stratum A or C. Stratum C evaluated ribociclib/sonidegib in skeletally mature patients with SHH-MB, TP53 wildtype with chr9q loss and/or PTCH1 mutation. Tumor, blood, and CSF samples were analyzed.

RESULTS

From 2018-2022, 68 patients enrolled: 33 in A (22 Grp3/4-MB, 11 EPN); 28 in B (15 HGG, 13 other); 7 SHH-MB in C. The RP2D was gemcitabine 1250mg/m2 IV day 1, 15 and ribociclib 350mg/m2 PO 1-21 days for A; trametinib 0.025mg/kg PO days 1-14 and ribociclib 280mg/m2 PO days 7-21 for B; and not established for C. DLTs included neutropenia (A), thrombocytopenia (B), mucositis (B), and rash (C). The 6-, 12-, and 24-month progression-free survival (PFS) was 42%(26%-58%), 18%(8%-33%), and 12%(4%-26%) in A, 18%(7%-34%), 4%(1%-15%), and 0% in B, 71%(30%-92%), 43%(13%-73%), and 0% in C. PFS beyond 2-years was observed in 3 Grp3/4-Subgroup3 MBs and 1 EPN. Amplification of CDK6, CCND2, and MYCN in serial CSF samples suggested a mechanism of resistance.

CONCLUSIONS

Ribociclib doublets are tolerated, and the lengthy survival of some patients suggests a selective benefit.
ETMR-06. PNOC031 - INTERNATIONAL TRIAL FOR EMBRYONAL TUMOR WITH MULTILAYERED ROSETTES
Authors: Hanson Derek , Chi Susan , Braunstein Steve , Elhalawani Hesham , Kool Marcel , Filbin Mariella , Gojo Johannes , Plasschaert Sabine , Von Hoff Katja , Margol Ashley , Kline Cassie , Molinaro Annette , Prados Michael , Mueller Sabine
Published: June 2024

Embryonal tumors with multilayered rosettes (ETMR) are aggressive central nervous system neoplasms with unfavorable prognosis, exhibiting rapid disease progression and frequent post-therapeutic relapse. The rarity of ETMR necessitates global collaboration to advance therapies. Radiotherapy (RT) has been associated with improved survival outcomes in ETMR with case series revealing that nearly half of ETMR patients treated without RT relapse within six months of diagnosis. However, RT is often withheld due to young patient age and neurodevelopmental considerations. This high-rate of on-treatment relapse is unique to ETMR and suggests that radiation-sparing regimens may be suboptimal. PNOC031 is an international collaboration, establishing a global clinical trial to innovate and improve therapeutic interventions for children with ETMR. Eligible patients with newly-diagnosed ETMR are stratified into three cohorts: Cohort 1 - gross total resection/RT-eligible patients to receive early focal radiotherapy (RT); Cohort 2 – gross total resection/not RT-eligible to receive high-dose chemotherapy with autologous stem cell rescue; and Cohort 3 – less than gross total resection or with metastatic disease to receive RT or high-dose chemotherapy per RT eligibility, based on age and tumor location. Cohort 1 will test the hypothesis if early RT improves outcomes in a pilot cohort of 20 patients. Patients will receive six weeks of induction chemotherapy, followed by focal irradiation and an additional six weeks of chemotherapy. Six-month progression-free survival will be assessed to determine the impact of radiotherapy on the rate of early relapse. Cohorts 2 and 3 will allow collection of uniform prospective clinical data using a common treatment backbone, to inform future clinical trial design for ETMR. Incorporating a myriad of correlative studies, including next-generation sequencing, cerebrospinal fluid analyses, microbiome profiles, and evaluations of social determinants of health alongside cognitive outcomes, will enhance comprehensive understanding of clinical responses and advance therapeutic options for this high risk disease.
ETMR-07. OVEREXPRESSION OF THE PLAG-GENE FAMILY MEMBER PLAG1 DURING MURINE BRAIN DEVELOPMENT LEADS TO ABERRANT EXPRESSION OF IMPRINTED GENES AND THE FORMATION OF MIDLINE BRAIN TUMORS
Authors: Vaillant Jan , Keck Michaela-Kristina , Wittmann Andrea , Hofmann Nina , Sievers Philipp , Chen Angela , Rozowsky Jacob S , Filbin Mariella G , Beroukhim Rameen , Bandopadhahay Pratiti , Jones David T W , Kutscher Lena M
Published: June 2024

BACKGROUND

The transcription factor PLAG1, ordinarily active during development, has been identified as overexpressed in several pediatric brain tumor entities, including H3 K27-altered diffuse midline glioma. Additionally, our group recently identified a novel type of embryonic CNS tumors with amplification of the related genes PLAGL1 and PLAGL2. How this aberrant PLAG family gene activation drives tumor formation is unknown. We hypothesize that aberrant activity of these transcription factors impedes normal differentiation, thereby fostering neoplastic transformation.

METHODS

To investigate this, we utilize transgenic mouse models engineered to exhibit targeted PLAG1 overexpression and loss of Trp53 during brain development. Following, we use bulk and single-cell RNA-seq to examine underlying mechanisms and are working on whole genome CRISPR-Cas9 screens to detect genetic dependencies in derived tumorsphere cultures.

RESULTS

We found that transgenic mice develop brain tumors in the midline. RNA-seq of these tumors suggests the activation of developmental (homeobox transcription factors) and imprinted genes e.g. H19 and Dlk1, the latter being similarly activated in pediatric CNS tumors with PLAGL1/2 amplification. Using single-cell RNA-seq of the resultant tumors, we compared the gene expression profiles of the tumor cells to a developmental mouse brain atlas. Tumor cells best correlated to radial glia stem cells and glioblasts, supporting the hypothesis of a developmental block caused by PLAG1 overexpression. A subpopulation of the tumor cells seemed to escape the radial glia cell state but were then ultimately locked in the OPC state. A similar mechanism was observed in H3 K27M diffuse midline gliomas.

CONCLUSION

Collectively, we provide evidence that PLAG1 overexpression drives pediatric brain tumor formation by inhibiting normal cellular differentiation. The ongoing CRISPR screen in PLAG1 and PLAGL1 overexpressing murine cell lines, ChIP-seq analysis of the murine tumors, and comparisons with human data and hNSC models aims to unveil the specific molecular mechanisms underlying tumor progression.
ETMR-10. DEVELOPMENT AND CHARACTERIZATION OF A NOVEL IMMUNOCOMPETENT ORTHOTOPIC MOUSE MODEL FOR THE STUDY OF EMBRYONAL TUMORS WITH MULTILAYERED ROSETTES (ETMRS)
Authors: Hervás-Corpión Irati , Zalacain Marta , González-Huarriz Marisol , Largaespada David A , Alonso Marta M
Published: June 2024

BACKGROUND

ETMRs are highly aggressive CNS embryonal tumors with a median survival of <12 months. They are characterized by the presence of multilayered rosettes, amplification of the C19MC microRNA cluster, and high expression of LIN28A; all which are used as diagnostic markers of ETMR. To understand more deeply the mechanisms involved in ETMR pathogenesis, as well as to test immune therapies, it is necessary to develop appropriate immunocompetent murine models that resemble human ETMRs, which are currently scarce. Thus, the aim of our study is the generation and characterization of a novel preclinical ETMR mouse model.

METHODS

The murine PNET cell line DF1-MYC, produced using a MYC overexpressing RCAS model on a C57BL/6J background, and corresponding allografts were implanted into the supratentorial region of 4-week-old NSG and immunocompetent NTV-a p53floxed mice. Mice were monitored and sacrificed. For efficacy studies, the survival curves were plotted according to the Kaplan-Meier method. For tumor histological analysis and immunohistochemistry, FFPE brain sections were stained with H&E or antibodies against Ki67, c-Myc and Lin28a. Transcriptional profile was characterized by RNA-seq.

RESULTS

DF1-MYC-bearing NP53 mice did not develop tumors except one mouse that showed a small tumor with multilayered rosettes. With the goal of achieving complete penetrance, we injected DF1-MYC cells orthotopically in NSG mice and allografts subsequently in NP53 mice. Specifically, our MYC384 allograft ETMR mouse model show a penetrance of 70% with a median survival of 36 days. Importantly, the MYC384 allograft model recapitulates histopathologic features of human ETMR, including the presence of highly proliferative undifferentiated cells with multilayered rosettes. Moreover, we are working on overexpressing Lin28a and c-Myc in MYC384 to create a more realistic molecular model of ETMR while allowing us to achieve 100% penetrance.

CONCLUSION

We describe MYC384 as a potential relevant immunocompetent mouse model of ETMR with almost complete penetrance.
ETMR-13. MARROW-ABLATIVE CONSOLIDATION CHEMOTHERAPY WITH AUTOLOGOUS HEMATOPOIETIC PROGENITOR CELL RESCUE (HDCT) DECREASES THE DEVELOPMENT OF CHOROID PLEXUS CARCINOMA (CPC)-SPECIFIC RELAPSE IN HIGH-RISK TP53-MUTATED (GERMLINE OR SOMATIC) YOUNG CHILDREN WITH NEWLY DIAGNOSED CPC
Authors: Yankelevich Maxim , Ozorio Diana S , Zaky Wafik , Lafay-Cousin Lucie , Margol Ashley , Toll Stephanie , Prados Michael , Gardner Sharon L , Hanson Derek , Quiroz Lina , Fox Javier E , Mueller Sabine , Finlay Jonathan L
Published: June 2024

BACKGROUND

CPC are childhood cancers in which the loss of TP53 function defines unfavorable disease. CPC-free survival rates have remained poor in patients with TP53 mutations and recent data revealed CPC-free survival of 29% with a non-marrow-ablative chemotherapy strategy. Previously reported results of the “Head Start” (HS) HDCT approach were limited by small patient numbers and incomplete TP53 mutation data. Consequently, the role of HDCT in TP53-mutated CPC remains unclear.

METHODS

We have analyzed data on TP53 status, CPC-free survival and second cancers from the largest cohort of patients who received initial therapy with the intent of undergoing HDCT.

RESULTS

Twenty-seven children with CPC received HS-like induction chemotherapy and 23 completed HDCT consolidation. Somatic or germline TP53 mutations were identified in 17 patients, 4 exhibited TP53 wild type (TP53wt); TP53 status remained untested in 6. Five-year CPC-free survival was 66% for patients with TP53 germline mutations (n=12), 40% for those with somatic tumor TP53 mutations (n=5) and 50% with confirmed TP53wt (n=4). Among patients with germline TP53 mutations, only 4/12 experienced CPC recurrences, 4 died from secondary cancers and 4 are currently alive. The 5-year CPC-free survival for 23 patients who underwent HDCT was 52%. All six survivors with TP53 mutations had undergone HDCT, and 5/6 avoided irradiation. Eight/12 patients with TP53 germline mutations and Li-Fraumeni Syndrome (LFS) developed second malignancies, including 6 patients in HDCT group and the remaining 2 patients who did not undergo consolidative HDCT.

CONCLUSIONS

Our data indicate that HDCT consolidation is associated with improved CPC-free survival compared with historical reports in children with TP53 mutated CPC. The ultimate development of second cancers affects outcomes for those with LFS, irrespective of HDCT treatment. These data justify the inclusion of HDCT in the prospective international trial under development for young children with newly diagnosed TP53 mutated CPC.
ETMR-17. CLINICAL DESCRIPTION OF PEDIATRIC CHOROID PLEXUS PAPILLOMAS FOR IDENTIFICATION AND VALIDATION OF HIGH-RISK CHARACTERISTICS
Authors: Fiedler Christian , Kordes Uwe , Thomas Christian , Hasselblatt Martin , Bison Brigitte , Behrens Lars , Kortmann Rolf-Dieter , Timmermann Beate , Pietsch Torsten , Rutkowski Stefan , Obrecht-Sturm Denise
Published: June 2024

BACKGROUND

Choroid plexus papilloma (CPP) and atypical CPP (aCPP) have an excellent prognosis. However, some CPP/aCPP relapse and may qualify for postoperative treatment.

METHODS

Patients from the International CPT-SIOP Registry with CPP/aCPP recruited in Germany between 2011–2023 were included and analysed according to initial staging (postoperative residual tumor [R+], meningeosis [M+]), biology, postoperative treatment and outcome.

RESULTS

Ninety-three patients were identified (male: n=53, female: n=40). Median age at diagnosis was 1.9(0.1–17.6) years. Initial staging was R0/M0 in n=63, R+/M0 in n=21, R0/M+ in n=5 and R+/M+ in n=4. aCPP was diagnosed in n=38. Methylation subtype was available for n=34:”adult” n=3, “pediatric-A” n=19 and “pediatric-B” n=12 (6/12 aCPP). Median follow-up was 5.5(±0.99) years. Twelve tumors relapsed: R0/M0 n=4, R+/M0 n=7, R+/M+ n=1. Two relapsed patients died. Eleven patients initially received ≥1 surgery. Most patients did not receive postoperative treatment (watchful waiting, n=86). Seven patients (R0/M0 n=3, R+/M0 n= 1, R0/M+ n=2, R+/M+ n=1) received chemotherapy. None was irradiated during first-line treatment. Histology and biology had no impact on PFS (5y-PFS: CPP 88.6±4.9%, aCPP 82.7±6.5%, pPFS=0.3; “adult” 33.3±27.2%, “pediatric-A” 93.8±6.1%, “pediatric-B” 72.9±13.5%, pPFS=0.08). Patients with R0/M0-status had better 5y-PFS than those with R+ and/or M+ (90.4±4.1% vs. 77.7±8.1%, p=0.05). Neither incomplete resection alone, nor meningeosis alone did relate to inferior PFS in CPP/aCPP separately analysed (R+: p=0.07/p=0.07, M+: p=0.5/p=0.4). In the whole cohort, R+ was associated with inferior survival (5y-PFS R+ 72.2±9.8% vs. R0 91.3±3.7%, p=0.009). It remains unclear if R+-patients benefit from chemotherapy (5y-PFS watch-and-wait vs. chemotherapy 75.1±9.8% vs. 50.0±35.4% pPFS=0.7).

CONCLUSION

Incomplete resection appears to have impact on the risk for relapse in CPP/aCPP. It remains unclear whether those patients benefit from postoperative chemotherapy.
ETMR-19.BCOR/L1-ALTERATIONS REWIRE HISTONE REGULATION TO INDUCE ONCOGENIC PATHWAYS IN PEDIATRIC CENTRAL NERVOUS SYSTEM TUMORS
Authors: Bruckner Katharina , Lötsch-Gojo Daniela , Gabler Lisa , Wang Shanzheng , Kirchhofer Dominik , Labelle Jenna , Madlener Sibylle , Senfter Daniel , Schmitt-Hoffner Felix , Federico Aniello , Koster Jan , Dorfer Christian , Tauziède-Espariat Arnault , Pahnke Jens , Hovestadt Volker , Beck Alexander , Schueler Julia , Haberler Christine , Berger Walter , Filbin Mariella G , Kool Marcel , Gojo Johannes
Published: June 2024

BACKGROUND

Central nervous system (CNS) tumors with BCOR internal tandem duplication (ITD) or BCOR/L1 fusions are recently described tumor types with distinct molecular characteristics and poor clinical outcome. BCOR and its homologue BCORL1 are essential components of the non-canonical polycomb repressor complex (PRC) 1.1 thereby acting as epigenetic regulators exerting a profound impact on central cellular mechanisms. However, the influence of BCOR/L1-alterations on the functionality of PRC1.1 in pediatric CNS tumors remains understudied.

METHODS

We performed bulk as well as single-cell/nucleus RNA sequencing (scRNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq) of CNS tumor tissue harboring BCOR-ITD or BCOR/L1 fusions. Additionally, BCOR/L1-altered, patient-derived cell models were used for downstream in vitro analyses.

RESULTS

ChIP-Seq analysis demonstrated binding of both KDM2B and mutant BCOR/L1 at PRC1.1 target genes whereas PRC1/2-mediated histone modifications H3K27me3 and H2AK119ub were absent. In addition, PRC1.1 target gene loci were characterized by high H3K27ac levels indicating increased transcriptional activity in BCOR/L1 mutant samples. Indeed, PRC1.1 targets such as FGFR1, GATA6, and ERBB3 were found to be upregulated in bulk transcriptome (n=37) analyses. Using scRNA-seq (n=10), we resolved a transcriptionally distinct cell population, specific for BCOR/L1-driven CNS tumors, which expressed high levels of PRC1.1 target genes. Besides PRC1.1 target genes, the targetable receptor tyrosine kinases PDGFR/FGFR(1/3), and IGF1R were found to be upregulated in pediatric BCOR/L1-altered CNS cancers. Accordingly, drug screens of patient-derived cell models revealed sensitivity towards small molecule inhibitors targeting the respective pathways. This translated well in anti-tumor effects of the FGFR/PDGFRA inhibitor nintedanib in BCORL1::NUTM2HP-fused patient-derived xenograft bearing mice.

CONCLUSIONS

Our data demonstrate for the first time that BCOR/L1-altered CNS tumors are driven by dysfunction of PRC1.1 histone modifications inducing profound transcriptomic changes ultimately activating oncogenic pathways. We further identified first feasible therapeutic targets including FGFR and PDGFR which may be leveraged for improved therapy of patients suffering from this aggressive tumor type.