bluuebunny/crossref_metadata_2025_split huggingface dataset:
IMMU-05. TARGETING THE DYSREGULATED DNA METHYLOME DURING CAR T CELL MANUFACTURING IMPROVES THEIR FITNESS IN IMMUNOCOMPETENT BRAIN TUMOR MODELS
Authors: Yi Zhongzhen , VanNoy Elton , Lee Abigail , Chiappinelli katherine , Haydar Dalia 
Published: June 2024

Abstract

BACKGROUND
Epigenetic reprogramming and T-cell exhaustion are key factors impacting the effectiveness of chimeric antigen receptor (CAR) T-cell immunotherapies in brain tumors. These processes are regulated by DNA methylation, an epigenetic modification that is crucial for gene regulation. Here, we investigated whether targeting the dysregulated DNA methylome in engineered immune cells can improve their anti-tumor efficacy.

METHODS
We optimized a transduction protocol that incorporates adding DNA methyltransferase inhibitors (DNMTi) early during the manufacturing process of murine CAR T-cells targeting B7-H3. We then used standard in vitro assays and immunocompetent glioma models to evaluate whether DNMTi treatment improved CAR T-cell effector functions by regulating activation, memory differentiation, and cytokine responses in adoptive T-cells.

RESULTS
In repeated-stimulation assays, CAR T-cells generated in the presence of DNMTi exhibited significantly higher levels of expansion and persistence compared to CAR T-cells without DNMTi exposure. Notably, CAR T-cells manufactured in the presence of DNMTi persisted up to 12 repeat stimulations, in contrast to a maximum of 7 stimulations for CAR T-cells generated without DNMTi treatment. Moreover, DNMTi-treated CAR T-cells expanded up to 55-fold higher than T-cells generated without DNMTi treatment upon repeated-stimulation with B7-H3-positive glioma cells. This was also associated with remarkably enhanced secretion of immune-stimulatory cytokines that persisted across repetitive stimulations. Furthermore, DNMTi-treated CAR T-cells exhibited greater cytotoxicity at lower effector-to-target ratios compared to untreated CAR T-cells, with sustained differential cytotoxicity even after the 4th stimulation. Preliminary in vivo data from immunocompetent glioma models further support the potential of DNMTi pre-treatment, showing improved T-cell persistence and reduced dose requirements. Mechanistic studies suggest that DNMT inhibition enhances B7-H3 CAR T-cell anti-tumor activity by regulating memory differentiation of CAR T-cells early in the production phase.

CONCLUSION
This study proposes that DNMTi pre-treatment may offer a promising approach for optimizing CAR T-cell manufacturing and enhancing performance in brain tumors.
IMMU-09. PHASE 2 TRIAL USING INDOXIMOD-BASED CHEMO-IMMUNOTHERAPY FOR PATIENTS WITH CHILDHOOD BRAIN CANCER: INTERIM ANALYSIS OF THE GCC1949 STUDY (NCT04049669)
Authors: Johnson Theodore S , Pacholczyk Rafal , Ring Eric K , Aguilera Dolly , Castellino Robert C , Fangusaro Jason R , Eaton Bree R , Chi Susan , Yeo Kee Kiat , Hummel Trent R , Berrong Zuzana , Creager Julianne , Ingerski Lisa , Schniederjan Matthew , Huang Chenbin , Satpathy Sarthak , Thomas Beena E , Sadek Ramses F , Kennedy Eugene P , Bhasin Manoj K , MacDonald Tobey J , Munn David H 
Published: June 2024

Abstract

BACKGROUND
Brain tumors are the leading cause of pediatric cancer-related death.

METHODS
We report interim outcome data from an ongoing multi-site phase 2 study (NCT04049669) of indoximod-based chemo-immunotherapy for patients 3-21 years of age with either recurrent brain cancer (ependymoma, medulloblastoma, high-grade glioma) or newly diagnosed diffuse intrinsic pontine glioma (DIPG). Treatment is oral IDO pathway-inhibitor indoximod (38.4 mg/kg/day, divided BID) plus temozolomide (200 mg/m2/day for 5 days) in 28-day cycles. Patients who may benefit from additional irradiation receive indoximod during the radiation regimen and are analyzed separately.

RESULTS
Planned accrual is 140; 80 patients have been treated to date. Estimated median follow-up time was 23.5 months (range 0.2 - 42.7 months), and indoximod-based therapy has been well tolerated. Estimated median overall survival (OS) was 23.8 months for recurrent ependymoma (n=31); 11.5 months for recurrent medulloblastoma (n=22); 5.7 months for recurrent HGG (n=18, includes diffuse midline glioma except primary DIPG); and 15.0 months for newly diagnosed DIPG (n=9). Single-cell TCR and RNA sequencing of serially collected blood samples was used to identify expanded CD8+ T cell clones with late-effector phenotypes, and their emergence was associated with significantly improved survival. In patients treated with immunotherapy, radiographic measurement of objective response is challenging, owing to the high incidence of mixed responses and pseudoprogression events. In our recently published phase 1 trial of indoximod (NCT02502708, Neuro-Oncology 26:348-361, 2024) we showed that 41% of relapsed patients had MRI evidence of objective response in at least one tumor using RAPNO criteria, and that these “responder” patients had 3-fold better median OS (25.2 months, p=0.007) than non-responders (7.3 months). To date, the phase 2 data is similar.

CONCLUSIONS
The GCC1949 phase 2 study is replicating the published phase 1 results, and we will present updated results from the first 80 patients in the GCC1949 trial.
IMMU-10. DEVELOPING NOVEL CHIMERIC ANTIGEN RECEPTOR THERAPIES FOR PAEDIATRIC HIGH GRADE GLIOMA
Authors: Davenport Alexander J , Lertsumitkul Leesa , Cross Ryan S , Jenkins Misty R 
Published: June 2024

Abstract
Paediatric high-grade gliomas (pHGG), particularly Diffuse Midline Glioma (DMG), present a formidable challenge in oncology. Due to the aggressive biology and location of pHGGs the implementation of adult treatment modalities (surgery, chemotherapy, and radiotherapy) is severely limited resulting in pHGG remaining a terminal disease. Thus, there is a pressing and urgent unmet clinical need for the development of innovative therapeutics. We will demonstrate the identification of cell surface targets using mass spectrometry proteomics. We have developed novel binders and engineered them into second-generation CAR T cells. We will present pre-clinical in vivo intracranial mouse models examining the efficacy of novel CAR T cell therapies. We have recently reported effective CART cell targeting of HER2 in DMG, and presently we will also demonstrate superior efficacy of additional CAR T cell targeting, both in vitro and in vivo in preclinical PDX models of DMG. We will present new data that CAR T cells targeting EphA3 show curative efficacy in pre-clinical models of DMG. Recognising that single targeting CAR T cells are unlikely to provide long-term clinical benefit, we will also present our combination approaches using CAR T cells targeting antigens such as GD2, EGFR, HER2, EphA3, CD276 and CD63. We are expanding our research to other CAR T combination strategies focusing on immune-modulating drugs such as checkpoint inhibitors or co-stimulatory agonists. We are committed to advancing CAR T cell therapies for pHGG patients and their families with an aim to aid in the development of much-needed new therapeutic options.
LGG-05. REPORT ON PEDIATRIC BRAIN TUMOR CONSORTIUM (PBTC)-029B, A PROSPECTIVE PHASE 2 CLINICAL TRIAL OF SELUMETINIB IN TREATING YOUNG PATIENTS WITH RECURRENT/PROGRESSIVE LOW-GRADE GLIOMA: NEW RESULTS ON STRATA 2, 5, AND 6 WITH UPDATED LONG-TERM SURVIVAL OUTCOMES ON STRATA 1, 3, AND 4
Authors: Fangusaro Jason , Onar-Thomas Arzu , Poussaint Tina Young , Lensing Shelly , Ligon Azra H , Lindeman Neal , Banerjee Anuradha , Kilburn Lindsay , Lenzen Alicia , Pillay-Smiley Natasha , Pollack Ian F , Robison Nathan , Partap Sonia , Qaddoumi Ibrahim , Landi Daniel , Jones David T W , Stewart Clinton F , Fouladi Maryam , Dunkel Ira J 
Published: June 2024

Abstract

BACKGROUND
PBTC-029B was a phase 2 trial evaluating efficacy of selumetinib (up to 26 courses) in children with recurrent/progressive low-grade glioma. We report new results on strata 2, 5, and 6 as well as update long-term survival outcomes on strata 1, 3, and 4.

METHODS
Stratum 2 enrolled children with pilocytic astrocytoma (PA) whose tumor screened negative for the BRAF-KIAA1549 fusion and the BRAFV600E mutation. Stratum 5 enrolled children with non-PA whose tumor screened positive for one of these two BRAF aberrations. Stratum 6 enrolled children who consented to tissue screening, but there was an assay failure. Responses were based on T2/FLAIR.

RESULTS
Stratum 2: among 14 patients, there was 1 partial response (PR), 7 stable disease (SD) and 6 progressive disease (PD) with overall response rate (ORR) of 7.1%. Two-year progression-free survival (PFS)/overall survival (OS) were 57.1/100%, respectively. Stratum 5: among 23 patients, there was 1 complete response, 4 PR, 12 SD and 6 PD with ORR of 21.7%. Two-year PFS/OS were 74.8%/100%, respectively. Stratum 6: among 26 patients, there were 7 PR, 14 SD and 5 PD with ORR of 26.9%. Two-year PFS/OS were 72.0%/100%, respectively. Long-term outcomes have now been evaluated in strata 1, 3, and 4. Stratum 1 enrolled patients with PA whose tumor screened positive for one of the two BRAF aberrations; stratum 3 enrolled patients with neurofibromatosis type-1 (NF1) associated pLGG; and stratum 4 enrolled non-NF1 optic pathway/hypothalamic tumors. Among strata 1, 3, and 4, the current median follow-up for patients without events are 60.4, 60.4, and 58.1 months, respectively. Five-year PFS/OS are 30.8%/88.9%, 54.2%/100%, and 51.0%/100%, respectively.

CONCLUSIONS
These data demonstrate that selumetinib provides tumor stability and responses among diverse pLGG tumors as well as show that many patients will achieve long-term disease control even several years after stopping treatment.
LGG-06. THREE PRACTICAL CHALLENGES IN IMPLEMENTING RAPNO RESPONSE ASSESSMENT FOR PEDIATRIC LOW-GRADE GLIOMAS
Authors: Bag Asim Kumar , Robinson Giles W 
Published: June 2024

Abstract
The RAPNO criteria for pediatric low-grade gliomas (pLGGs), designed to improve upon the RANO criteria, are increasingly being employed to assess treatment responses. However, the adoption of the RAPNO guidelines in our clinical trials has revealed some notable challenges that stymie their practical implementation. These challenges should be addressed to render the guidelines more comprehensive and facilitate their widespread adoption. Definition of tumor burden should be modified: The current guidelines define tumor burden as the sum of the products of the longest tumor diameter and its longest perpendicular diameter. While this approach generally works, implementing it in optic pathway gliomas involving the nerve and subtotally resected pLGGs where the longest diameter is often disproportionally larger than the perpendicular diameter creates a challenge. The result is an inaccurate measure of tumor burden as well as poor reproducibility. Progressive disease should be confirmed with follow-up imaging. Unlike response confirmation, guidelines do not recommend confirmation of progression. Since pLGGs grow slowly, the change in diameters between two consecutive scans is often so small that it can be indistinguishable from measurement error. This is particularly problematic in smaller tumors and in diffusely infiltrating tumors, in which minor measurement change can erroneously shift response to progressive disease. Definition of target lesion should be more specific: pLGGs can recur focally without involving the entire previously treated residual tumor. Based on RAPNO guidelines, the target lesion includes both the growing and the stable residual components. This poses a challenge and can result in a serious underestimate of efficacy, particularly with biologic therapy, when the response of the recurrent focal tumor is major or complete but, by the current criteria, only registers as stable disease or minor response. Our discussion will show real-world examples of these challenges and propose recommendations to enhance the practical application of RAPNO criteria.
LGG-11. UNDERSTANDING THE TRANSCRIPTIONAL HETEROGENEITY OF PEDIATRIC LOW-GRADE GLIOMAS AND ITS IMPLICATION FOR TUMOR PATHOPHYSIOLOGY
Authors: Boisvert Michelle , Perera Ashwyn A , Jeang John , Condurat Alexandra L , Tsai Jessica W , Novikov Dana , Collins Jared , Morin Eric , Woods Jared , Zhou Kevin , Chacon Madison , DiGiacomo Jeromy , Kumbhani Rushil , Wang Dayle , Taylor Michael D , Hansford Jordan R , Ludlow Louise E A , Jabado Nada , Ligon Keith L , Beroukhim Rameen , Bandopadhayay Pratiti , Jones David T W 
Published: June 2024

Abstract

BACKGROUND
Pediatric low-grade gliomas (pLGGs) are the most frequent brain tumors in children and comprise a heterogeneous group of tumors with different locations, histologic subtypes, ages at presentation, and clinical behavior. Tumors frequently respond to treatment with chemotherapy or radiation therapy, but they can regrow after a period of quiescence, requiring further therapy. Thus, a deeper understanding of the molecular processes involved in these tumors is required to develop therapeutic strategies that are effective against their disease mechanisms.

METHODS
To better understand the cellular behaviors of this heterogenous group of tumors, we have employed single-cell and single-nuclei RNA sequencing technologies to analyze a large-scale dataset (&gt;250,000 cells) of 55 pLGGs across many histological subtypes (pilocytic astrocytoma, pleomorphic xanthoastrocytoma, pilomyxoid astrocytoma, DNET, ganglioglioma, RGNT, diffuse astrocytoma, SEGA, glioneuronal, oligodendroglioma).

RESULTS
Analysis of this data identified a heterogenous population of cell types and cell states, detecting mature and progenitor-like astrocytes and oligodendrocytes, as well as cells exhibiting senescence or cycling programs. Moreover, we identify a significant immune infiltrate, comprised primarily of microglia. In addition to heterogeneity within pLGG tumors, heterogeneity between LGG subtypes represents another layer that stratifies pLGG biology. We performed a compositional analysis of the cell types present in these tumors and compared transcription signatures and gene expression programs across shared cellular populations of histologically and genetically distinct pLGGs. Finally, we used spatial transcriptomic data to investigate and annotate the cellular architecture of multiple pLGGs with BRAF mutations and draw comparisons to findings from our single-cell and single-nuclei transcriptomic analysis.

CONCLUSIONS
Our analysis of human pLGGs at the single-cell and single-nuclei resolution provides critical insight into the heterogenous biological activities that constitute these tumors.
LGG-17. NATURAL HISTORY AND MANAGEMENT OF INCIDENTALLY DISCOVERED BRAIN LESIONS SUSPECT FOR NEOPLASM IN CHILDREN
Authors: Delhez Celine C A , Kersbergen Karina J , van Meeteren Antoinette Y N Schouten – , van den Bergen Janneke C 
Published: June 2024

Abstract

BACKGROUND
The rise in neuroimaging has resulted in an increase of incidentally discovered brain lesions suspect for a neoplasm (‘incidentaloma’) in children. With the experience in our national hospital, we aim to diversify and broaden the knowledge on the management and natural history of pediatric incidentaloma.

METHODS
A retrospective analysis of all incidentaloma patients in the Princess Maxima Center for Pediatric Oncology from June 2018 until March 2023.

RESULTS
Our research population consists of 23 patients (10M/13F) with an incidentaloma. The lesions were mostly located in the cerebellum (21.7%), thalamus and ventricle (both 17%) and cerebral hemisphere (13%) The average age at diagnosis was 7.9 years (range 0-15 years) and the mean duration of follow-up was 4.6 years (range 0-11 years). The initial management was clinical and radiological follow-up in seventeen (74%), resection in five (22%) and biopsy in one patient (4%). Pathological examination performed in the six neurosurgical patients revealed low grade gliomas (LGGs) in three patients, medulloblastoma in one and plexus papilloma in one patient respectively. The pathological analysis of the patient with biopsy only was indecisive. One patient became symptomatic with clear tumor growth on imaging after 6.8 years of follow-up. Biopsy showed a H3K27M mutant diffuse midline glioma. She died 8.1 years after initial diagnosis. In 11 other patients radiographic changes (mostly tumor progression) were observed with a median of 23 months after diagnosis (range 3-70 months). Two of these underwent complete resection of an LGG.

CONCLUSIONS
For most incidentalomas, clinical and radiological follow-up is sufficient. As late disease progression can occur as seen in our patient who became symptomatic after 7 years, this follow-up should be long-term. Future studies should focus on identifying (radiological) prognostic factors for tumor progression, so follow-up of incidentaloma can be more personalized.
LGG-21. IMMUNE MICROENVIRONMENT PROFILING OF BRAF-FUSION PILOCYTIC ASTROCYTOMA: DIRECTIONAL PRIORITIZATION OF IMMUNOTHERAPEUTIC TARGETS
Authors: Tripathi Shashwat , Najem Hinda , Heimberger Amy , DeCuypere Michael 
Published: June 2024

Abstract

BACKGROUND
The immune microenvironment of pediatric gliomas is relatively understudied despite being a leading cause of childhood mortality. Pilocytic astrocytomas (PA) are the most common pediatric glioma and surgical resection is often curative. However, PAs are not always amenable to surgery and can have significant long-term morbidity and mortality. The ten-year progression-free survival for PA patients with significant residual tumor is less than 50% and other non-surgical treatment options are frequently necessary.

METHODS
To identify PA patients that may be responsive to immune checkpoint inhibitors and to guide prioritization of available immunotherapeutic treatments, orthogonal immune profiling strategies were used to identify patients that may benefit from the next generation of immune therapeutics. Because the KIAA1549-BRAF fusion is expressed in 70% of PA, we prospectively collected patients to comprehensively characterize the unique immune biology of these tumors using nanostring profiling, scRNASeq, and SeqIF™ multiplex staining.

RESULTS
The tumor microenvironment of BRAF-fusion PA was notable for antigen presentation and the interaction of CD11c+ cells with T cells through Lck+ immunological synapses. PA CD11c+CD206+ dendritic cells localized to vessel walls and were positive for TIM3 expression, an immune checkpoint marker. A unique highly activated microglia subcluster was identified that morphologically resembled T cells expressing TNF and TIM3. Our results are consistent with others that suggest potential benefit in targeting tumors with elevated MAPK activity. Finally, the expression of other immune checkpoints such as Lag-3, PD-1, and TIGIT are minimally co-expressed, suggesting that T cells are not in a state of exhaustion, as seen in adult high-grade gliomas.

CONCLUSIONS
Analysis of BRAF-fusion PA identified a unique highly activated P2RY12+ microglia population dispersed throughout the tumor microenvironment, active antigen presentation between a CD11c+ antigen presenting cells and T cells, and a unique therapeutic opportunity for targeting TIM3.
LGG-24. PEDIATRIC GANGLIOGLIOMA WITH GERMLINE BRCA2 MUTATION
Authors: Gupta Anya , Lechpammer Mirna , Shatara Margaret , Rocco Abbey , Beck Mary , McHugh Michele , Lampe Ashley , Meyer Ashley , Ogle Andrea , Cluster Andrew , Abdelbaki Mohamed S , Brossier Nicole M 
Published: June 2024

Abstract

BACKGROUND
BRCA1 and BRCA2 are genes associated with breast and ovarian cancer development in adults. Their influence on brain tumor formation is less understood.

METHODS
Retrospective review

RESULTS
An 11 year-old girl was diagnosed with ganglioglioma after presenting with seizures. Tumor sequencing revealed three mutations: a PDAP1-BRAF fusion, a BRAF-HIP1 non-canonical fusion, and a pathogenic BRCA2 variant D252*fs. Upon further review, a family history of breast cancer in the grandmother and several great-aunts was identified, and genetic testing confirmed this mutation to be germline. We then conducted an institutional review and identified a second pediatric low-grade glioma (pilocytic astrocytoma) patient with a pathogenic mutation in BRCA2 (T3085Fs*26) in addition to a BRAF-KIAA1549 fusion; the family declined germline BRCA2 testing. BRCA1/2 knockout models have demonstrated that both genes play a role in brain development. Concurrent BRCA2 and TP53 loss triggers formation of early onset murine medulloblastoma, a finding not observed with TP53 loss alone. In human patients, heterozygous and biallelic mutations in BRCA2 were identified as risk factors for medulloblastoma development in a recent integrative genomic analysis. Retrospective review

CONCLUSION
We report two cases of BRCA2 mutation in pediatric low-grade gliomas, one of which was confirmed to be germline. While somatic variants of BRCA2 have been reported in both high- and low-grade glioma, their role in these tumors has not been established to date. The BRCA2 tumor predisposition syndrome increases the risk of some types of brain tumors such as medulloblastoma, although the risk remains low compared to the risk of developing breast or ovarian cancer later in life. More evidence is required to determine whether BRCA2 germline mutations can similarly increase the risk of glioma formation.
LGG-32. MALIGNANT TRANSFORMATION OF PEDIATRIC LOW-GRADE GLIOMA TO SECONDARY HIGH-GRADE GLIOMA - REPORT FROM THE GERMAN BRAIN TUMOR STUDIES
Authors: Perwein Thomas , Gielen Gerrit H , Kandels Daniela , Bison Brigitte , Karremann Michael , Kühn Alexander , Sturm Dominik , Spix Claudia , Warmuth-Metz Monika , Stock Annika , van Buiren Miriam , Monoranu Camelia M , Hartmann Christian , Friker Lea L , Eyrich Matthias , von Bueren André O , Driever Pablo Hernáiz , Witt Olaf , Koch Arend , Pietsch Torsten , Benesch Martin , Kramm Christof M , Gnekow Astrid K 
Published: June 2024

Abstract

BACKGROUND
Malignant transformation (MT) of pediatric low-grade glioma (pLGG) to secondary high-grade glioma (sHGG) is a rare but momentous event. We explored its clinical, epidemiologic, and molecular characteristics and risk factors.

METHODS
Forty-eight pediatric patients with histology-based or radiological (n=4) diagnosis of primary LGG (median age 10.2 years [range, 0.7–16.9]) and subsequent sHGG were identified within registries of the HIT-network from 1996-2019. For 29 patients, tumor specimens of both pLGG and corresponding sHGG were available for neuropathological review and studied genetically.

RESULTS
MT occurred after median 4 years (range, 0.5-14) following LGG diagnosis. Its 15-year cumulative incidence was 1.6±0.4% (23/1586 SIOP-LGG-2004 patients), but 11.7±4.1% (9/100) for diffuse pLGG WHO-grade 2 (DG2). Clinical risk factors for MT were spinal location and prior dissemination. MT was accompanied by an increment of nuclear p53 accumulation (20/29 tumors), cytogenetic and molecular alterations. CDKN2A/B homozygous deletions (7/12 tumors), 1p/1q alterations (4/12) and ATRX loss (3/12) were the most common acquired alterations detected in sHGG. 8/16 tumors were unclassifiable by methylation profiling. DG2s (n=19), harboring IDH-1 mutation in 3/9 cases, progressed to diffuse WHO-grade 3 (n=8) or grade 4 HGG (n=9), two developed gliomatosis cerebri. Circumscribed LGG (PA, n=13; GG, n=7; PXA, n=4; DNET, n=1) typically harbored MAPK/ERK pathway alterations (BRAF-/NTRK-/FGFR-fusions, n=5/9; BRAFV600E mutation, n=4/12) and transformed to non-diffuse HGG (n=14), but also to diffuse grade 4 HGG. H3 K27M-/BRAFV600E co-mutation in two of these patients eventually resulted in MT to fatal diffuse midline glioma. Thirty-five sHGG patients received radio-chemotherapy. Overall survival at 5 and 10 years following MT was 49±8% and 31±8%.

CONCLUSIONS
Our findings underline the importance of careful long-term follow-up of patients with pLGG. Repeated resection/biopsy of recurrent/progressing or “atypical” tumors should be pursued and include molecular typing to identify patients at risk for MT and initiate appropriate treatment.