bluuebunny/crossref_metadata_2025 huggingface dataset:
EXTH-30. GENETIC ALTERATIONS THAT DEREGULATE RB AND PDGFRA SIGNALING PATHWAYS DRIVE TUMOR PROGRESSION IN IDH2-MUTANT ASTROCYTOMA
Authors: Tateishi Kensuke , Miyake Yohei , Nakamura Taishi , Fujii Satoshi , Yamamoto Tetsuya , Cahill Daniel , Wakimoto Hiroaki
Published: November 2024

In IDH-mutant astrocytoma, IDH2 mutation is quite rare and biological mechanisms underlying tumor progression in IDH2-mutant astrocytoma remain unclear. In this presentation, we report a unique case of IDH2 mutant astrocytoma, CNS WHO grade 3 that developed tumor progression. We performed a comprehensive genomic and epigenomic analysis for primary and recurrent tumors and found that both tumors harbored recurrent IDH2R172K and TP53R248W mutation with CDKN2A/B hemizygous deletion. We also found amplifications of CDK4 and MDM2 with PDGFRA gain in the recur- rent tumor and upregulated protein expressions of these genes. We further developed, for the first time, a xenograft mouse model of IDH2R172K and TP53R248W mutant astrocytoma from the recurrent tumor, but not from the primary tumor. Consistent with parent recurrent tumor cells, amplifications of CDK4 and MDM2 and PDGFRA gain were found, while CDKN2A/B was identified as homozygous deletion in the xenografts, qualifying for integrated diagnosis of astro- cytoma, IDH2-mutant, CNS WHO grade 4. Cell viability assay found that CDK4/6 inhibitor and PDGFR inhibitor potently decreased cell viability in recurrent tumor cells, as compared to primary tumor cells. On the other hand, in accord with our previous study that IDH1 inhibitor was not sufficient to induce anti-tumor effects in IDH1-mutant high-grade gliomas (Tateishi K et al. Cancer Cell. 2015), we did not find decreased cell viability nor histone methylation status changes after mutation specific IDH2 inhibitor treatment of recurrent cells. These findings underlie that gene alterations that activate retinoblastoma (RB) signaling pathways and PDGFR may drive tumor progression and xenograft formation in IDH2-mutant astrocytoma, which is equivalent to progressive IDH1-mutant astrocytoma. Also, our findings suggest that these genomic alterations may represent therapeutic targets in IDH2-mutant astrocytoma.
EXTH-31. TARGETINGMIR-19B/PPP2R5E REGULATORY AXIS TO MAXIMISE ALKYLATING AGENT EFFICACY: A NEW AVENUE TO COUNTERACT TEMOZOLOMIDE RESISTANCE IN RECURRENT GLIOBLASTOMAS
Authors: Kashani Elham , Hlavackova Kristyna , Sadowski Martin , Maragkou Theoni , Krebs Philippe , Vassella Erik
Published: November 2024

Glioblastoma, IDH-wildtype (GBM), notorious for its inevitable recurrence despite aggressive multi-modal standard of care, presents a pressing need for novel treatment paradigms. The extensive DNA damage caused by the frontline DNA alkylating agent, temozolomide (TMZ) is counteracted by intricate or acquired survival mechanisms. Through functional microRNA screens we identified miR-19b-overexpressing clones possessing extra fitness in presence of escalating doses of TMZ. Our study uncovers a previously unrecognized TMZ resistance mechanism governed by miR-19b. Notably, miR-19b attenuation intensified DNA damage response and CHEK1 and CHEK2 phosphorylation, instigating persistent DNA lesions and consequently priming GBM cells for heightened TMZ cytotoxicity. Mechanistically, we showed that miR-19b exerts its function by targeting PPP2R5E, a subunit of protein phosphatase PP2A, frequently downregulated in GBM. We uncovered that the elevated DNA damage response in the miR-19b-attenuated cells was a consequence of enhanced nuclear and mitochondrial ROS production. This in turn, induced ROS-mediated senescence, and an intriguing susceptibility to ferroptosis, possibly due to increased ROS-mediated lipid peroxidation. Of note, all these phenotypes were reversed in GBM cells with concomitant miR-19b and PPP2R5E attenuation, demonstrating that miR-19b exerts its role in TMZ resistance by targeting PPP2R5E. In line with this finding, an orthotopic human-derived glioblastoma stem cell xenograft model confirmed that PPP2R5E attenuation not only decreases TMZ cytotoxicity in the brain, but also at the spinal metastatic location. Consistently, treating cells with the PP2A-activating drug FTY720 or knocking down endogenous PP2A-inhibiting proteins mirrored the effects of miR-19b attenuation in enhancing TMZ cytotoxicity. This intricate interplay between miR-19b and PPP2R5E underscores a novel strategy to modulate the TMZ response, highlighting promising results in our pre-clinical models. In conclusion, our findings advocate for the therapeutic targeting of the miR-19b/PPP2R5E regulatory axis as a potential novel strategy in the pursuit of effective therapeutic interventions for the formidable recurrent GBM tumours.
EXTH-33. COMBATING TUMOR HETEROGENEITY IN GLIOBLASTOMA WITH A NOVEL CAR-BASED PLATFORM
Authors: Wilkinson Daniel , Lerner Emily , Fecci Peter
Published: November 2024

Tumor heterogeneity is a major hindrance impeding success of antigen targeting immunotherapies, such as chimeric antigen receptor (CAR) T cells, in solid tumors. CAR T cells engineered to target EGFRvIII, IL13Rα2, and HER2 have mostly failed clinically to treat glioblastoma, because these antigens are typically only expressed on a subset of a tumor cells within a patient. Thus, finding a surface target that more universally characterizes tumor cells will likely be critical if antigen-specific immunotherapies are to succeed in glioblastoma and other solid tumors. Recently, we uncovered a mechanism whereby CD8 T cells can directly kill tumor cells independently of tumor-expressed major histocompatibility complex (MHC)-I. We found this mechanism to be dependent on NKG2D expression on T cells and NKG2D ligand (NKG2DL) expression on tumor cells. Interestingly, NKG2DL expression was not limited to MHC-I-deficient tumor cells, nor was it limited to gliomas, but NKG2DL expression characterized a variety of solid tumor types. Therefore, NKG2DL is potentially an ideal target for immune-based therapy. Here, we developed a bi-specific fusion protein comprised of the extracellular domain of NKG2D linked to an anti-CD3scFv. Thus, T cells will be redirected to target NKG2DL-expressing tumor cells. We have termed this fusion protein Bi-specific Engagers without Antigen Requirements (BEAR). To ensure local, intratumoral delivery of BEAR, we engineered an EGFRvIII-targeting CAR T cell to secrete BEAR (VIII CAR Engineered with BEAR; VIII “CARE-BEAR”). VIII CARE-BEAR demonstrated potent tumor kill in both in vitro and in vivo tumor heterogeneity models. Moreover, we engineered an EGFRwt-targeting (D2C7) CARE-BEAR to exemplify the potential utility of CARE-BEAR beyond glioblastoma.
EXTH-36. SHIFTING FROM EPIGENETICS TO THE EPICHAPEROME: HSP90 AS A THERAPEUTIC TARGET FOR H3K27M DIFFUSE MIDLINE GLIOMA (DMG)
Authors: Sbergio Stefanie-Grace , Pajovic Sanja , Vadivel Arun Anguraj , Watanabe Jun , Sheth Javal , Canty Laura , Chiosis Gabriela , Nitz Mark , Hashizume Rintaro , Hawkins Cynthia
Published: November 2024

Diffuse midline gliomas (DMG) are lethal pediatric brain tumours, the majority of which have truncal histone (H3K27M) mutations. To investigate cellular vulnerabilities of histone mutant cells we generated oligodendrocyte precursor cells (OPC) isogenic cell lines and performed a high-throughput synthetic lethality drug screen (2400 small molecules). This identified HSP90 inhibitors as a potential therapeutic option for H3K27M DMG. We hypothesize that epichaperome HSP90 inhibitors present a new therapeutic approach targeting multiple aspects of DMG oncogenicity. HSP90 inhibitors, PU-H71 and PU-HZ151, effectively reduced viability of DMG lines in vitro in the low nanomolar range and result in caspase mediated cell death (p<0.0001 1 uM, p<0.05 500 nM, n=6). PU-HZ151 treated mice had a survival benefit vs control mice injected with orthotopic DMG xenografts (p=0.0012). In diseased cells, activated HSP90 forms a scaffold defined as the epichaperome. To unravel the molecular mechanisms of epichaperome inhibition in DMG cells, we performed epichaperomics – a pull down of epichaperome HSP90 with co-chaperones and clients followed by LC-MS/MS analysis. We identified an interactome enriched with proteins involved in cell cycling, RAS/MAPK signaling, immune response, and metabolic reprogramming. Proteomic and phosphoproteomic profiling of DMG cells post-PU-HZ151 treatment provided insights into the direct downstream effects critical for maintaining DMG viability, identified functional vulnerabilities primed by epichaperome inhibition including downregulation of cell cycling, and upregulation of HSF1 mediated cellular response to stress. In silico screening and kinase enrichment analysis highlighted CSNK2A1 as a top active kinase in DMG cells following PU-HZ151 treatment. To enhance the therapeutic efficacy of epichaperome inhibition, we employed the CSNK2A1 kinase inhibitor, CX-4945, in combination with PU-HZ151, resulting in the effective ablation of DMG patient cells in vitro. These data highlight the potential of epichaperome inhibitors for DMG treatment, as they target multiple DMG oncogenic pathways.
EXTH-42. GLIOMA-DERIVED CD200 PROMOTES TUMOR GROWTH AND SUPPRESSES NK CELL AND CD8 T CELL ANTI-GLIOMA ACTIVITY
Authors: Raphael Itay , Graner Michael , Moertel Christopher , Kohanbash Gary , Olin Michael
Published: November 2024

Immune-checkpoint inhibitors, such as anti-PD1 and anti-CTLA4, have emerged as promising therapeutic options for several malignancies yet show little efficacy against malignant brain cancers. CD200 is a newly recognized immune-checkpoint which is expressed by a marid of cell types, modulating immune homeostasis through multiple receptors. There is currently limited information regarding CD200 effects in brain tumors. Furthermore, while it is well accepted that CD200 binding to its inhibitory receptor induces a pro-tumorigenic environment through its ability to suppress immune responses, there are increasing evidence that CD200 could also have anti-tumor characteristics. Here we evaluated the role of tumor-derived CD200 on anti-glioma immunity. We demonstrate that CD200 is expressed across glioma types, is shed from tumor cells, and increases over time in serum of patients undergoing immunotherapy. Transcriptomic analysis of CD200 knockout (KO) glioma models reveals that glioma-derived CD200 significantly modifies the glioma tumor microenvironment (TME), not only through immune regulation but also through immune-independent pathways, such as tumor metabolism. Furthermore, we show that CD200 KO gliomas have reduced proliferation and are rejected by their hosts. Downstream analysis revealed that rejection of CD200 KO gliomas relied on a functional adoptive immune system, while decreased proliferation was linked to reduced CXCL10 production by the CD200 KO gliomas. Additionally, we demonstrate that glioma-mediated CD200 strongly suppresses anti-glioma NK cell function within the tumor microenvironment (TME), while secreted CD200 inhibits the priming of antigen-specific CD8 T cells in the lymphatic. Notably, NK cells were essential for the initial rejection of CD200 KO gliomas, while CD8 T cells played a critical role in establishing durable anti-tumor responses. Our work provides new mechanistic insights on glioma-derived CD200-mediated immunosuppression and an untapped potential for targeting CD200 by immunotherapies for malignant gliomas.
EXTH-75. IMMUNOVIROTHERAPY WITH PP2A AND PD-1 INHIBITION IN PEDIATRIC HIGH-GRADE GLIOMA
Authors: Kang Kyung-Don , Frederico Stephen , Fan Aaron , Gary Sam , Zhang Zhuo , Zhou Li , Markert James , Bernstock Joshua , Friedman Gregory
Published: November 2024

Pediatric high-grade gliomas (HGGs) represent a significant clinical challenge with poor survival rates. Engineered oncolytic herpes simplex virus (oHSV) has shown potential in several clinical trials at targeting HGGs through their direct lytic effect and induction of an immune response. We have learned from our clinical trial experience (NCT02457845) that a critical barrier to more durable response is augmenting and sustaining the anti-tumor immune response generated by oHSV. LB-100, a protein phosphatase 2A (PP2A) inhibitor, is known to enhance T-cell activity. We hypothesized that LB-100 with anti-PD-1 therapy would overcome the immunosuppressive barriers, enhancing the immunotherapeutic effects of oHSV and improve survival in an immunocompetent murine model. We investigated the therapeutic impact of clinically available, next-generation oHSV, M002, which expresses murine interleukin-12, combined with LB-100 and PD-1 inhibition compared to M002 with LB-100 or anti-PD-1 antibody, each therapy alone, or control by measuring median survival and changes in the tumor immune microenvironment. The triple combination of M002, LB-100, and anti-PD-1 antibody significantly extended median survival compared to control (45 days vs 22.5 days, P=0.001) or each treatment alone, and compared to M002 and LB-100 (44 days vs 28 days, P=0.017) or M002 and anti-PD-1 (45.5 days vs 41 days, P=0.023). This increase in survival was correlated with a robust increase in CD45+ immune cell infiltration and a reduction in T-regulatory cells. We will further investigate the changes in the tumor microenvironment to better understand the specific contributions of different immune cell populations. These data support the hypothesis that LB-100 enhances the efficacy of oHSV by amplifying T-cell-mediated immune responses against tumor cells. This combination therapy demonstrates a promising strategy that warrants further exploration and potential clinical application, emphasizing the critical role of targeting multiple aspects of immune regulation to enhance the efficacy of oncolytic virotherapy in pediatric tumors.
EXTH-83. CHARACTERIZATION OF SPLICING ABERRATIONS INDUCED BY PRMT5 INHIBITION IN GLIOBLASTOMA
Authors: Huo Longfei , Sharma Pratibha , Tsai Tsung-Lin , Chen Xiaohua , Yu Chunlei , Xu Jihong , Ju Zhenlin , Li Ziyi , Scherle Peggy , Vaddi Kris , Baiocchi Robert A , Sampath Deepa , Shukla Sachet , Puduvalli Vinay K
Published: November 2024

Glioblastoma (GBM) are lethal tumors with limited treatment options, with a high unmet need for novel therapies. PRMT5, an arginine methyltransferase that regulates several histone and non-histone targets, is overexpressed in cancers including GBM and is a promising therapeutic target given its role in promoting oncogenic processes. Here, we characterized the effects of pharmacological inhibition of PRMT5 by the brain-penetrant, orally bioavailable inhibitors, PRT811 and PRT808 on treatment-induced splicing aberrations using a panel of patient-derived glioma stem cells (GSC) and organotypic human glioma slice cultures. Changes in protein expression upon PRMT5 inhibition were assessed using reverse phase protein array (RPPA) analysis. Additionally, splicing aberrations due to PRMT5 inhibition in were tested in several GSCs using RNA-seq. We observed a potent reduction of symmetrical dimethylation of arginine (SDMA protein marks by both PRMT5 inhibitors across various GSC lines and ex-vivo brain tumor tissue slices. Notably, GSCs with both mutant and wild-type p53 displayed similar sensitivity to PRMT5 inhibition, independent of MTAP status. Moreover, PRMT5 inhibition elicited reduced cell proliferation, altered cell survival pathways, and apoptosis. RNA-seq analysis revealed that splicing alterations affecting numerous oncogenes and regulatory factors, encompassing 42 cancer driver genes, 80 splicing factors, and 42 transcriptional factors across these GSC lines, with specific splicing events observed in nuclear and cytoplasmic subcellular compartments. Additional analysis is ongoing to determine which of the aberrant transcripts are translated to yield tumor specific neoantigens that can be potential targets for tumor specific immune strategies. These results underscore the efficacy of pharmacological PRMT5 inhibition in genetically and epigenetically diverse GSCs, and highlight its potential for developing novel immune and non-immune therapeutic strategies against GBM.
QLTI-01. ASSESSING THE EFFECTIVENESS OF SUPPORT FROM ST. JUDE CHILDREN’S RESEARCH HOSPITAL TO VIETNAMESE TEAM IN TREATMENT FOR CHILDREN WITH BRAIN TUMORS
Authors: Nguyen Hoa Thi Kim , Bui Lan Ngoc , Phan Duy Canh , Dao An Thi Thanh , Nguyen Anh Hoang Mai , Hoang Thach Ngoc , Do Thanh Cam , Van Nguyen Dinh , Handayani Andini , Blair Sally , Lam Catherine G , Qaddoumi Ibrahim
Published: November 2024

BACKGROUND

Treatment for children with brain tumors requires multidisciplinary team (MDT) which is lacking in Vietnam which negatively impacts outcome. This study aims to describe the implementation and promotion of MDT approach in Vietnam with the support of St. Jude Children’s Research Hospital.

METHODS

We conducted a prospective descriptive study of St. Jude Children’s Research Hospital’s activities with the Vietnamese team between August 2023 and March 2024 and its impact on education, patient care and disseminating of MDC approach in Vietnam.

RESULTS

Onsite and online training were provided for the Vietnamese team during this time. The onsite training included exchange visits for both teams and St. Jude support for Vietnamese colleagues to attend regional and international neuro-oncology conferences. Online case discussions have been held every month from January 2024 and there are 40-60 participants each meeting from 5 main oncology centers in Vietnam. There are 3- 4 complex case discussions each meeting. A zalo group (a social media platform) for Vietnamese doctors (92 doctors) with multidisciplinary team members was established. After discussion, references and summaries of each case were distributed to the zalo group. For emergency cases, email consults are requested directly for timely input. In addition, key educational textbooks covering different disciplines of neuro-oncology (pathology, radiology and medical) were provided to different Vietnamese teams. All participants (92 doctors) found the online discussion (100.0%) benefical to further their knowledge in different fields (chemotherapy, radiation, pathology and surgery) and the outcome of consultations which guided teams to manage difficult cases. For some cases, pathology samples with local reports are sent to St. Jude to review the diagnosis and classification.

CONCLUSIONS

Training plays an important role in bringing knowledge and building team-based experience for Vietnamese clinicians in the treatment for children with brain tumor.
QLTI-05. EUROPEAN NEURO-ONCOLOGY QUALITY ASSURANCE (ENOQUA): AN EORTC BRAIN TUMOR GROUP STUDY
Authors: Razis Evangelia , Hau Peter , Gorlia Thierry , Andratschke Nicolaus , Baumert Brigitta , Lohmann Philipp , Vernadou Anastasia , Gempt Jens , De Vos Filip
Published: November 2024

INTRODUCTION

Neuro-Oncology, a complex and multidisciplinary field that is relatively recent, lacks well-established quality assurance measures and standards for patient care.

METHODS

We assessed the performance of 14 potential quality indicators across 19 EORTC Neuro-Oncology centers to validate these indicators as effective measures of quality. For each center, we abstracted records from 20 patients diagnosed with glioblastoma in 2018 who were not enrolled in an investigational study. We tested associations between patient survival, center characteristics, and the performance of these quality measures.

RESULTS

Most centers met several standard requirements, suggesting their potential acceptance for prospective validation. IDH expression data was universally recorded in the patients’ chart. Performing MRI within 72 hours of surgery and providing patient education for chemotherapy correlated with improved overall survival (OS). Standards met in the majority of centers were the presence of a multidisciplinary plan, a radiation plan and the extent of surgery recorded in the chart, as well as the referral for radiation within six weeks of diagnosis. Preliminary results indicate that academic centers outperformed others in most measures, although analysis is ongoing. Performance varied significantly across centers; some standards were consistently met poorly, highlighting areas needing improvement. Lack of universal acceptance of certain practices as necessary and/or important may render some standards inappropriate for further development. Final analysis will be presented at the meeting.

CONCLUSION

We are developing a comprehensive set of standards and measures for QA in neuro-oncology, which will require future prospective validation.
QLTI-08. PREDICTING POOR HIGH-VALUE CARE OUTCOMES FOLLOWING SURGICAL RESECTION OF MULTIFOCAL GLIOBLASTOMA
Authors: Chakravarti Sachiv , Pulya Ritvik , Oak Atharv , Ranganathan Sruthi , Jimenez Adrian , Mukherjee Debraj
Published: November 2024

Presenting with dismal prognoses, treatment of multifocal GBM (mGBM) requires extensive medical infrastructure. Individualized assessment for patients at risk of extended length of stay (LOS) and nonroutine discharge disposition, described as high-value healthcare outcomes, has not previously been described. To develop predictive models for extended LOS and nonroutine discharge disposition for mGBM patients. All mGBM patients undergoing surgical resection at our institution (January 1, 2009-December 31, 2020) were included. Predictive models for nonroutine discharge disposition (discharge to a non-home environment) and extended LOS [upper quartile of the LOS for all patients included in the present study’s cohorts (>6 days)] were developed using multivariate logistic regression models. Optimism-corrected C-statistics for each model were calculated using 1000 bootstrapped samples in order to correct for potential bias associated with the limited population size. The Hosmer-Lemeshow test was used to evaluate model goodness of fit and calibration. A total of 137 mGBM patients were included in the present study. Most patients were male (40.1%), white (83.2%), not Hispanic/Latino (97.8%), not married (55.5%) and underwent elective surgery (85.4%). The average age among our patient cohort was 55.41 ± 13.17, the average KPS score was 77.23 ± 14.54 and the average mFI-5 was 0.613 ± 0.760. On bivariate analysis, older age (p=0.015) and decreasing Karnofsky Performance Status (KPS) score (p<0.001) were significantly associated with nonroutine discharge disposition while emergency admission (p=0.010) and increasing frailty (mFI-5) score (p=0.003) were significantly associated with extended LOS. On multivariate analysis, increasing age (p=0.031) and decreasing KPS (p<0.001) predicted nonroutine discharge while emergent admission (p=0.023) and greater mFI-5 (p=0.044) predicted extended LOS. Our models for nonroutine discharge and extended LOS had optimism-correct c-statistics of 0.7507 and 0.7309 respectively and displayed adequate calibration. Following external validation, our models may have utility as a risk stratification tool for this multifocal GBM patient populations.
QLTI-09. CLINICAL TRIALS IN NEURO-ONCOLOGY: DESIGN, LOGISTICS, CHALLENGES, AND PRACTICAL CONSIDERATIONS
Authors: Pawar Vikas , Roy Vijaylaxmi , Sreegiriraju Vijay , Goel Pallavi , Sadasivam Subhashini , Ghanekar Yashoda , Madiraju Surya , Ray Amit
Published: November 2024

Timely, secure and reliable transportation, precise handling and storage of biological specimens are critical for the success of clinical research. Research in neuro-oncology often involves complex assays such as next-generation sequencing where the integrityof brain tumor specimens is paramount. These challenges are pronounced in most Lower Middle-Income Countries (LMIC), due to climatic factors and infrastructure limitations, necessitating stringent measures to preserve sample quality and their genetic data integrity for downstream analysis. In this study, we conducted extensive cohort analysis on 80 tissues randomly picked samples of the 3600 samples collected across India to assess the impact of collection protocols, transportation logistics, and long-term storage on the genetic material of tissues. The quality and quantity of the isolated nucleic acids was determined by BioAnalyzer and Qubit parameters. Tissue samples were collected and stored at -80°C in RNAstable® within 4-12 hrs of collection. The DNA and RNA obtained from tissue samples stored for over one year was found to be of good quality with corresponding DNA Integrity Number (DIN) and RNA Integrity Number (RIN)between 7-9. Also, optimum quantity of DNA and RNA was obtained for whole exome and transcriptome sequencing. Upon sequencing, these samples showed good read coverage of 100X or more. These findings provide critical insights into the measures necessary for optimizing sample preservation and transportation to ensure accurate research outcomes. The results indicate that appropriate sample collection, transportation, and long-term storage of bio-specimens can be used effectively for future research. Additionally, the outcome underscores the potential for long-term studies in neuro-oncology using archived biological samples without compromising data integrity.
RTID-02. PERSONALIZED PEPTIDE VACCINATION AMONG 173 PATIENTS WITH GLIOBLASTOMA
Authors: Latzer Pauline , Zelba Henning , Battke Florian , Reinhardt Annekathrin , Shao Borong , Biskup Saskia
Published: November 2024

Current treatment outcome of patients with glioblastoma (GBM) remains poor. Following standard therapy, recurrence is universal with limited survival. GBM tumors from 173 patients were analyzed for somatic mutations to generate a personalized peptide vaccine targeting tumor-specific neoepitopes. In agreement with their treating physician, patients added a personalized peptide vaccine to their treatment as an individual healing attempt. Patients were monitored from October 2015 until August 2023. We retrospectively evaluated their clinical courses and the results of their immune monitoring data. Among all patients, including 70 treated prior to progression (primary) and 103 treated after progression (recurrent), the median overall survival from first diagnosis was 31.9 months (95% CI: 25.0-36.5). Adverse events were infrequent and were predominantly grade 1 or 2. An immune response to at least one of the vaccinated peptides was detected in blood samples of 87 of 97 (90%) monitored patients. T-cell responses to vaccinated neoepitope peptides were durable in most patients. Significantly prolonged survival was observed for patients with multiple vaccine-induced immune responses (53 months) compared to those with no/low induced responses (27 months; P=0.03). Altogether, our results highlight that the application of personalized neoantigen-targeting peptide vaccine is feasible and represents a promising potential treatment option for GBM patients. This is the largest real-world observation involving GBM patients safely treated with a personalized peptide vaccine to date. This real-world observation will be translated into a clinical trial to evaluate the specific contribution of the neoantigen vaccine.
RTID-05. STUDY PROTOCOL: A MULTICENTER, INTERNATIONAL RANDOMIZED CONFIRMATORY TRIAL: LOW-ENERGY X-RAY INTRAOPERATIVE RADIATION THERAPY (LEX-IORT) VS. ADJUVANT FRACTIONATED STEREOTACTIC RADIOTHERAPY (FSRT) IN THE MANAGEMENT OF BRAIN METASTASES (LEXIMATE)
Authors: Diehl Christian D , Acker Güliz , Brehmer Stefanie , Ganslandt Oliver , Giordano Frank A , Hamed Motaz , Kahl Henning , Münter Marc , Layer Julian P , Sarria Gustavo R , Schneider Matthias , Shiban Ehab , Wagner Arthur , Meyer Bernhard , Combs Stephanie E
Published: November 2024

BACKGROUND

Fractionated stereotactic radiotherapy to the resection cavity boosts local control of resected brain metastases significantly. However, start of systemic tumor-directed treatment may be protracted and in-hospital times prolonged. Lately, lex-ioRT of BM has been described as a safe and effective one stop-shop treatment modality with a 1-year local control rate of up to 98% while potentially improving patient convenience. Study Design: The LEXIMATE-trial is a multicenter, international, randomized open-label confirmatory trial comparing lex-IORT with FSRT of resected BM. In the experimental arm, INTRABEAM (Carl Zeiss Meditec AG) is used to deliver IORT by application of 50-kV photons at a standard dose of 30 Gy prescribed to the applicator surface. Standard linear accelerator or Gamma Knife based FSRT (3-7 fractions) to the surgical bed is used in the control arm. The primary endpoint is the cumulative incidence of local recurrences (as per RANO-BM) considering death without prior local recurrence as competing event. Inclusion criteria include histologically confirmed BM with indication for resection according to EANO-ESMO/ASCO-SNO-ASTRO guidelines, ≤5 other brain lesions compatible with BM and amenable to radiosurgery and history of solid cancer or CT scan suggestive for localized or metastasized solid cancer (except germ cell tumors, lymphoma, small-cell lung cancer). The resection cavity must be <5cm in size, IORT doses to brainstem or optical tract may not exceed 8 Gy. Study design: Randomized, open-label, non-inferiority. Sample size: 70 patients per group to show a non-inferiority of the experimental therapy compared to the control therapy with a power of approximately 80%.

DISCUSSION

The best radio-oncologic procedure for resected BM remains under debate. The LEXIMATE-trial offers an opportunity to provide more solid prospective data on effectiveness, safety and patient comfort both for established and new RT techniques.
TMET-03. ONCOGENIC STAT3 PROMOTES TUMOR GROWTH VIA STIMULATION THE SCAP- AND SREBP-1-REGULATED LIPOGENIC PATHWAY
Authors: Fan Yunzhou , Zhang Rui , Wang Chao , Pan Meixia , Geng Feng , Zhong Yaogang , Su Huali , Kou Yongjun , Mrinalini Rajeev , Mo Xiaokui , Han Xianlin , Lefai Etienne , Guo Deliang
Published: November 2024

Augmented lipogenesis is a hallmark of cancer. In addition, signal transducer and activator of transcription 3 (STAT3) is aberrantly activated and associated with poor prognosis in multiple cancers. Whether oncogenic STAT3 has an intrinsic and causal link to lipogenesis in cancer remains unclear. Here, we show that inhibition of STAT3 significantly alters the lipid profile of tumor cells, including free fatty acids and derived membrane structural phospholipids (phosphatidic acid, phosphatidylinositol, phosphatidylserine and sphingomyelin), this change results in cell death which could be rescued by lipids (oleic acid and palmitoleic acid) supplementation, while suppressing the gene and protein expression of major mediators of the lipogenic pathway including sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP), SREBP-1, fatty acid synthase and stearoyl-CoA desaturase 1. Furthermore, we show that STAT3 binds the promoter of SCAP, SREBP-1a and SREBP-1c, to promote their transcription in tumor cells. Finally, targeting STAT3 in a xenograft mouse model blocked glioblastoma growth and lipogenic enzyme expression. Our study reveals a novel regulatory pathway of STAT3-SCAP/SREBP-1 involved in tumor growth in vitro and in vivo, connecting STAT3 signaling with SCAP- and SREBP-1-mediated lipogenesis.
TMET-10. TARGETING PGM3 TO INHIBIT HEXOSAMINE PRODUCTION IS AN EFFECTIVE APPROACH TO TREAT GLIOBLASTOMA
Authors: Su Huali , Zhong Yaogang , Geng Feng , Fan Yunzhou , Kou Yongjun , Chiang Cheng-yao , Mo Xiaokui , Magaki Shino , Cloughesy Timothy F , Lefai Etienne , Yong William H , Chakravarti Arnab , Guo Deliang
Published: November 2024

Hexosamine biosynthesis pathway (HBP) mediated by a series of enzymes is highly upregulated in many cancers to promote the glycosylation of proteins and lipids, while which enzyme in this pathway is better to serve as anti-tumor target is unclear. Here, we found targeting GFAT1, the initial and rate-limiting enzyme in HBP, fails to inhibit the growth of glioblastoma (GBM), the most lethal brain tumor, due to this cancer dramatically elevating NAGK-mediated hexosamine salvage pathway. In contrast, targeting PGM3, the latter enzyme in HBP, blocks both de novo hexosamine synthesis and salvage pathways, effectively inhibiting GBM growth. We further identified HBP enzymes are upregulated by SREBP-1, a key lipogenic transcriptional factor. In turn, this upregulation promotes SREBP-1 activation to stimulate lipogenesis via stabilization of its key transporter SCAP by N-glycosylation modification. Together, our study uncovered a previously unrecognized HBP-SCAP-SREBP-1 feedforward loop and demonstrated targeting PGM3 is an effective approach to treat GBM.
TMET-12. TARGETING AMINO ACID METABOLIC VULNERABILITIES IN GLIOMAS
Authors: Ohba Shigeo , Teranishi Takao , Hirayama Akiyoshi , Hitachi Keisuke , Yamaguchi Hisateru , Natsumeda Manabu , Tateishi Kensuke , Pieper Russell , Hirose Yuichi
Published: November 2024

Isocitrate dehydrogenase (IDH) wild-type gliomas and IDH mutant gliomas are similar in histologic appearance but differ in their genetic and metabolic backgrounds. This study aimed to reveal the difference in metabolites between IDH-wildtype glioma and IDH-mutant glioma, and to find the effective treatment according to the status of IDH in gliomas. Two artificial cell lines made from human astrocyte were used: NHAE6E7hTERTRas (IDH-wildtype) and NHAE6E7hTERTIDHmut (IDH-mutant). Using capillary electrophoresis- and ion chromatography–coupled mass spectrometry, the amount of asparagine was lower in NHAE6E7hTERTRas cells compared with NHAE6E7hTERTIDHmut cells, whereas the amount of glutamine, glutamate and 2-oxoglutarate in NHAE6E7hTERTIDHmut cells was lower than NHAE6E7hTERTRas cells. L-asparaginase, which converts asparagine into aspartate, was more effective in NHAE6E7hTERTRas cells than NHAE6E7hTERTIDHmut cells. L-asparaginase induced autophagy and inhibition of autophagy by 3-MA suppressed L-asparaginase-induced antitumor effect, which meant that the antitumor effect was at least partially due to the L-asparaginase-induced autophagy. Pharmacological or genetical inhibition of GLUD1 which converts glutamate to 2-oxoglutarate, suppressed proliferation of the cells by inducing ROS and apoptosis in NHAE6E7hTERTIDHmut cells. ROS inhibitor, NAC suppressed GLUD1 inhibitor-induced ROS, apoptosis, and cytotoxicity in NHAE6E7hTERTIDHmut cells, revealing that cytotoxicity by GLUD1 inhibitor was at least partially due to the inhibitor-induced ROS. The experiments using mutant IDH1 overexpressed glioma cell line showed similar sensitivity to GLUD1 inhibitor to NHAE6E7hTERTIDHmut, which suggested that the difference of sensitivity to GLUD1 inhibitor was due to the status of mutant IDH. In vivo experiments, L-asparaginase suppressed the growth of xenografted glioma cells without mutant IDH, whereas GLUD1 inhibitor inhibited the proliferation of xenografted glioma cells with overexpressed mutant IDH1. In conclusion, L-asparaginase and Glud1 inhibitor will be new therapeutic option for IDH-wildtype glioma and IDH-mutant glioma, respectively.
TMET-13. SPATIAL METABOLOMIC CHANGES OF NUCLEOTIDE IN THE BRAINS OF ORTHOTOPIC MOUSE GLIOMA MODEL AFTER BORON NEUTRON CAPTURE THERAPY (BNCT)
Authors: Kondo Natsuko , Kobayashi Nao , Sakurai Yoshinori , Suzuki MInoru , Yamaguchi Shinichi , Ikegawa Masaya
Published: November 2024

Glioblastoma is the most lethal primary brain tumor. Boron Neutron Capture Therapy (BNCT) is a tumor-selective particle radiation therapy, in which high-LET α-particles and recoil 7Li are produced by the capture reaction between 10B and thermal neutrons and it has extended the prognosis of glioblastomas [Kawabata S, et al., Neuro-Oncology Advances 3(1), 1–9, 2021]. Augmented synthesis and use of nucleotide triphosphates is critical and universal metabolic dependency of tumor cells [Mullen, N.J., Singh, P.K. Nat Rev Cancer 23, 275–294 (2023)]. However, the effects of BNCT on metabolism of purine and pyrimidine in brain tumors and the surrounding normal brain are unknown. We spatially investigated metabolomic change in brains of orthotopic mouse glioma model, before and 2, 7, and 14 days after BNCT using mass spectrometry imaging (MSI). By separating tumor and non-tumor areas and performing Partial Least Squares Regression calculations, we have successfully visualized tumor-specific metabolites including adenine (ATP, ADP) and uridine (UTP, UDP-glucose, UDP-GlcNAc) with MSI. Of note, the signal of top-scored tumor specific metabolite, UDP-GlcNAc dramatically decreased and disappeared as the tumor regressed. Furthermore, the signal of ADP which was supposed to be released from tumor, colocalized with invading tumors along with corpus callosum. The value of adenylate energy charge, ([ATP]+0.5[ADP]/[ATP]+[ADP]+[AMP]) in the surrounding normal brain of the untreated tumor-bearing mouse increased up to 0.37 and decreased gradually down to 0.32 with BNCT, approaching to the value of normal control mouse brain, 0.27. These metabolomic changes reflected the tumor-killing effect and restoration of energy charge of surrounding normal brain by BNCT and have potential significance for development of biomarker or diagnosis.
TMET-14. ENOLASE 2 IS A UNIQUE METABOLIC VULNERABILITY INDUCED BY THE 1P19Q CODELETION IN OLIGODENDROGLIOMAS
Authors: Udutha Suresh , Batsios Georgios , Gillespie Anne Marie , Viswanath Pavithra
Published: November 2024

Gliomas are devastating primary brain tumors in adults. The presence of an isocitrate dehydrogenase mutation combined with a chromosomal 1p/19q codeletion discriminates oligodendrogliomas from astrocytomas. The goal of this study was to leverage metabolic vulnerabilities induced by the 1p/19q codeletion for oligodendroglioma therapy. The 1p19q codeletion results in loss of enolase 1 (ENO1), which converts 2-phosphoglycerate to phosphoenolpyruvate during glycolysis. Here, we show that enolase 2 (ENO2) is upregulated in patient-derived oligodendroglioma (SF10417, BT88, BT54) models relative to astrocytoma (BT142, SF10602) and normal human astrocytes. ENO2 is also elevated in oligodendroglioma patient biopsies relative to astrocytoma or gliosis. Mechanistic studies indicate that inhibiting MEK1 or ERK1 abrogates ENO2 expression, suggesting that the MAPK pathway upregulates ENO2 in oligodendrogliomas. Next, we examined the therapeutic potential of targeting ENO2 in oligodendrogliomas. Genetic ablation of ENO2 or pharmacological inhibition using POMHEX inhibited the viability of SF10417 and BT88 cells with IC50 values of ~50 nM. In contrast, the IC50 for BT142 and SF10602 astrocytoma cells was ~5-8 uM, highlighting the exquisite dependence of oligodendrogliomas on ENO2. However, ENO2 inhibition did not lead to cytotoxicity in patient-derived oligodendroglioma cells or intracranial tumor xenografts. To assess the metabolic consequences of ENO2 inhibition and identify potential compensatory alterations, we traced [U-13C]-glucose metabolism in vivo in mice bearing intracranial SF10417 tumors. Although POMHEX abrogated glycolytic metabolism downstream of 2-phosphoglycerate, it shunted glucose towards biosynthesis of serine, glycine, methionine and purine nucleotides, an effect that was driven by phosphoglycerate dehydrogenase (PHGDH), the rate-limiting enzyme for serine biosynthesis. Importantly, the novel PHGDH inhibitor PHGDH-D8 was synthetically lethal in combination with POMHEX in oligodendroglioma cells and the combination induced apoptosis in mice bearing intracranial SF10417 tumors. Collectively, we exploit a mechanistic understanding of metabolic vulnerabilities induced by the 1p19q codeletion to identify combined inhibition of ENO2 and PHGDH as a novel therapeutic opportunity for oligodendrogliomas.
TMET-25. WILD-TYPE IDH1 INHIBITS FERROPTOSIS IN GLIOBLASTOMA
Authors: Dunterman Madeline , Korimerla Navyateja , Murnan Kevin , Tommasini-Ghelfi Serena , Wahl Daniel , Stegh Alexander
Published: November 2024

De novo lipogenesis and the defense against oxidative lipid damage require large amounts of cytosolic NADPH. Our group has recently found that glioblastoma (GBM) up-regulate wild-type Isocitrate dehydrogenase 1 (referred to hereafter as ‘wt-IDH1high GBM) that, through oxidative decarboxylation of isocitrate, generates large quantities of alpha-ketoglutarate and cytosolic NADPH. We demonstrated that RNAi-mediated knockdown of wt-IDH1, alone and in combination with RT, slows the growth of patient-derived HGG xenografts, while overexpression of wt-IDH1 promotes intracranial HGG growth. Here, we demonstrate that wt-IDH1high GBM produce excess NADPH, which is a rate-limiting reductant that drives de novo fatty acid biosynthesis. Isotope tracer and liquid chromatography-based lipidomic studies indicate that wt-IDH1 supports the de novo biosynthesis of mono-unsaturated fatty acids (MUFAs), promotes the incorporation of monounsaturated, and reduces the abundance of oxidizable polyunsaturated (PUFA) phospholipids in the cell membrane. Conversely, the genetic ablation of wt-IDH1 or the pharmacologic inhibition of wt-IDH1 in tumor cells, using a brain-penetrant wt-IDH1-specific small molecule, revealed a significant increase in PUFA-containing lipid species harboring oxidized arachidonic tails. Of note, two lipid species, (PE16:0_20:4) and (PE18:0_22:4), previously reported to act as substrates for 15-lipoxygenase (15-LOX) - a key enzyme that facilitates lipid peroxidation - are enriched in tumor cells with wt-IDH1 compromise. Further, we found that the enhanced NADPH production in wt-IDH1high GBM, together with heightened biosynthesis of carbon precursors required for glutathione biosynthesis, increased levels of reduced glutathione (GSH), activate the phospholipid peroxidase glutathione peroxidase 4 (GPX4)-driven lipid repair pathway, which scavenges PUFA-containing lipid peroxides, known executioners of ferroptosis. These findings support elevated wt-IDH1 expression, the ensuing effect on the tumor lipidome, redox homeostasis, and protection against lipid peroxidation as contributors to GBM tumor growth and therapy resistance and point to the inhibition of wt-IDH1 as a ferroptosis-inducing strategy for the treatment of GBM.
TMET-27. MACHINE LEARNING-BASED IDENTIFICATION OF METABOLIC FLUXES IN PATIENT BRAIN TUMORS
Authors: Meghdadi Baharan , Mittal Anjali , Scott Andrew , Liang Ningning , Palavalasa Sravya , Achreja Abhinav , Kothari Alexandra O’Brien Ayesha , Zhou Weihua , Xu Jie , Lin Angelica , Wilder-Romans Kari , Edwards Donna , Wu Zhe , Feng Jiane , Andren Anthony , Zhang Li , Tarnal Vijay , Redic Kimberly , Qi Nathan , Lawrence Theodore , Lyssiotis Costas , Al-Holou Wajd , Wahl Daniel , Nagrath Deepak
Published: November 2024

Personalized oncology aims to match effective treatments for individual cancer patients based on the biology of an individual tumor. This approach is not possible for metabolic therapies due to our inability to quantify metabolic activity in patient tumors, even when patients are infused with 13C-glucose. We overcame this challenge by generating training data with a prior knowledge of 13C-glucose infused patient data and implementing a machine learning model to predict fluxes. We trained a convolutional neural network (CNN) to predict flux ratios. To validate our model, we compared predicted flux ratios to the experimental 13C-glucose-infused mouse models to predict treatment responses for: (1) pharmacologic inhibition of de novo GMP synthesis and (2) environmental serine restriction. Our GMP synthesis model predicted elevated GMP synthesis in GBM compared to cortex in a mouse model and discriminated between sources of GMP synthesis in patients. These findings allow prediction of potential responders to mycophenolate mofetil (MMF), which inhibits de novo but not salvage GMP synthesis. Furthermore, we previously showed that circulating serine uptake is higher in GBM than normal cortex, and a serine- and glycine-restricted diet slows tumor growth in mice. While de novo serine synthesis, circulating and microenvironmental-derived serine could account for serine sources in GBM, our model can distinguish between serine sources in patients, hence potentially predict response to dietary serine depletion. Thus, we have shown that our model may identify patients who will benefit from MMF treatment or a serine- and glycine-restricted diet, potentially enabling administration of highly effective personalized metabolic treatments for GBM patients.
TMIC-15. GUT MICROBIOTA CONTROLS NEUROFIBROMATOSIS-1 (NF1) OPTIC GLIOMA GROWTH THROUGH IMMUNE CIRCUIT MODULATION
Authors: Chatterjee Jit , Qi Xuanhe , Ouyang Megan , Mu Rui , Li Xuanwei , Bozeman Stephanie L , Eligator Talia , Schriefer Lawrence A , Rodgers Rachel , Baldridge Megan T , Gutmann David H
Published: November 2024

Changes in the gut microbiome can have profound effects on the nervous system through modulation of T cell and microglia function. Since our prior studies demonstrated that T cells and microglia positively regulate low-grade glioma growth through the establishment of T cell-microglia immune circuit, we sought to explore the impact of changes in the gut microbiota on tumor biology. For these studies, genetically engineered Neurofibromatosis type 1 (NF1) optic glioma (Nf1-OPG) mice were raised in a germ-free environment or treated with antibiotics to deplete gut bacteria. First, we demonstrated that Nf1-OPG mice raised in a germ-free (gnotobiotic) environment or treated with specific antibiotics lacked optic gliomas and had improved OPG-induced retinal pathology (increased retinal nerve fiber layer thickness). Second, germ-free and antibiotic-treated Nf1-OPG mice gavaged with fecal microbiota from Nf1-OPG mice raised in a standard barrier facility restored optic glioma growth. Third, we showed that both germ-free and antibiotic-treated Nf1-OPG mice exhibited reduced intra-tumoral CD8+ T cell content resulting from decreased microglia chemokine production. Fourth, we discovered a gut-brain paracrine axis whose interruption reduced optic glioma growth and attenuated retinal nerve fiber layer thinning. Collectively, these findings establish a mechanistic relationship between the gut microbiota and brain tumor growth relevant to potential therapeutic interventions for pediatric low-grade gliomas.
TMIC-73. SEX DIFFERENCES IN INTERFERON-GAMMA RESPONSES IN GLIOMA MICROENVIRONMENT
Authors: Leu Jia-Shiun , Tran Han Nhat , Ismail Taha S , Yun Kyuson
Published: November 2024

IFNγ is a cytokine with both pro- and anti-tumorigenic effects and its role in glioma immunotherapy resistance is not well understood. In the tumor microenvironment, T and NK cells produce IFNγ, which affects cellular phenotypes in most of the cancer and stromal cells since IFNγ receptor is ubiquitously expressed. IFNγ induces expression of molecules that confer resistance to immunotherapies, such as PDL1, PDL2, IDO1, and iNOS. The goal of this study is to elucidate cell type-specific responses to IFNγ in immune competent glioma models we developed that are resistant to immunotherapy. We intracranially injected male and female murine glioma cells into B6 and Ifng-/- honst mice to measure overall survival and perform immune phenotyping and single cell RNA-sequencing analyses. Ifnγ-/- hosts exhibited a shorter survival, and the proportion of GBM cells is higher in Ifng-/- hosts compared to wild type, indicating that the net effect of IFNγ signaling in glioma is anti-tumorigenic. In a recent study, we published that IFNγ-response pathway is enriched in the mesenchymal-like (MES-like) subtype of human GBM cells, compared to neutral-progenitor-like (NPC-like) and oligodendrocyte-progenitor-like (OPC-like) cells (Abdelfattah et al., 2022). To test our hypothesis that IFNγ signaling induces MES transition in glioma cells in vivo, we compared fractions of glioma cell subtypes in wildtype and Ifng-/- male and female hosts. In female Ifng-/- mice, MES-like GBM cell fraction was reduced while OPC-like fraction was increased, supporting our hypothesis. However, there was no difference in male hosts. Furthermore, gliomas grown in female B6 hosts showed higher infiltration of immune cells (CD45+), lymphocytes (CD3+) and fewer resident microglia cells (CD11b+CD45int), compared with Ifng-/- female hosts. In contrast, no significant difference in immune cell infiltration was observed between B6 vs Ifng-/- males. These results suggest an unanticipated and complex context-dependent role of IFNγ signaling in GBM, which include sex differences in its role in immune cell recruitment and MES transition in glioma cells.