bluuebunny/crossref_metadata_2025 huggingface dataset:
DDDR-22. USE OF BIOPSY-DERIVED TUMOR ORGANOIDS FOR PERSONALIZED DRUG TESTING IN RECURRENT GLIOBLASTOMA
Authors: Herold-Mende Christel , Woellner Amelie , Warta Rolf , Cao Junguo , Paul Adrian , Aquilla Maddalena , Jungwirth Gerhard , Wick Wolfgang , von Deimling Andreas , Unterberg Andreas , Krieg Sandro , Jakobs Martin
Published: November 2024

To date, there are no effective systemic treatment options for recurrent glioblastoma (GBM). Furthermore, often surgical resection is not possible and tumors have acquired an increased chemo- or radioresistance. Patient-derived tumor organoids (PDTOs) provide a new exciting tool to test individual treatment responses. Aim of this study was to assess the feasibility of a personalized PDTO-based drug testing even from rare material such as stereotactic biopsies. PDTOs were prepared based on single cell suspensions from tumor material obtained either from open GBM resections (reference data set, n = 37) or from stereotactic biopsies (n = 8). Drug response curves (6-9 doses) were performed for 9 drugs including commonly used drugs such as temozolomide, lomustine, etoposide and temsirolimus. Viability was measured using CellTiterGlo (Promega) to assess half-maximal inhibitory concentrations (IC50). Medical records were reviewed for survival and molecular information such as the MGMT methylation status. Drug testing on PDTOs from open resections allowed to adjust the test range for each drug. Additionally, a significant association between increased temozolomide sensitivity of PDTOs and both, MGMT methylation and increased survival was observed. However, in 59% of the cases, no sensitivity to any of the drugs was seen, and only 17% were highly sensitive to more than one drug. Subsequent drug testing on PDTOs from biopsies of recurrent GBM revealed sensitivity in 3/8 cases against one (n=2) or two (n=1) of the drugs. However, sensitivity against drugs varied substantially in a patient-individual manner. We successfully developed a workflow to test drug sensitivity on PDTO even from low starting material obtained from stereotactic biopsies. Association of clinical outcome and MGMT methylation with temozolomide sensitivity corroborated the strength of this approach. Furthermore, patient-individual treatment responses strongly suggest for a future personalized drug testing.
DDDR-29. MATRIX STIFFNESS INDUCED PHENOTYPE IN BRAIN METASTATIC BREAST CANCER CELLS DETERMINES RESPONSE TO THERAPY
Authors: Yakati Venu , Shevde Lalita A , Rao* Shreyas S
Published: November 2024

Breast cancer is the most prevalent form of cancer, representing 12.5% of all cancer cases diagnosed worldwide. Breast cancer cells can metastasize to distant organs (i.e., brain) and remain dormant for extended periods of time. This aspect makes it very difficult to treat these cells as they exhibit reduced growth as well as resistance to therapy. Despite advances in our understanding of breast cancer metastasis, the specific mechanisms that enable dormant cancer cells to resist therapeutics, particularly in brain metastatic breast cancer (BMBC), remain unclear. Herein, we employed brain tissue mimetic hyaluronic acid (HA) hydrogels of varying stiffness (i.e., ~0.4 kPa vs. ~4.5 kPa) to investigate the response to chemo or targeted therapy in dormant versus proliferative BMBC cells. It was revealed that BMBC cells grown on soft HA hydrogels (~0.4 kPa) displayed a non-proliferative (i.e., dormant) phenotype and exhibited resistance to Paclitaxel (PTX) or Lapatinib (LAP). However, BMBC cells grown on stiff HA hydrogels (~4.5 kPa) displayed a proliferative phenotype and sensitivity to PTX or LAP. Furthermore, we found that resistance to therapy was due to the enhanced expression of the serum/glucocorticoid regulated kinase 1 (SGK1) gene, mediated, in part, via the p38 mitogen-activated protein kinase (MAPK) pathway. Consequently, SGK1 inhibition using a SGK inhibitor in BMBC cells cultured on soft HA hydrogels resulted in a dormant-to-proliferative switch as well as response to PTX or LAP. In sum, our study demonstrated that matrix stiffness plays a major role in the dormancy-associated therapy response, mediated, in part, via the p38/SGK1 pathway.
DDDR-33. TRANSCRIPTOMICS-BASED NOVEL DRUG DISCOVERY IN DIFFUSE MIDLINE GLIOMA
Authors: Kaur Savneet , Leshchiner Dmitry , Watanabe Jun , Uchida Eita , Mineji Kentaro , Chen Bin , Hashizume Rintaro
Published: November 2024

Introduction. Pediatric high-grade gliomas are the most common cause of cancer-related death in children, of which the most malignant and devastating tumors include diffuse midline glioma (DMG). Recent availability of tumor samples and advances in next-generation sequencing enable the profiling of thousands of molecular features in DMG. We employ a system-based approach that uses gene expression as a representation of the molecular state, providing an avenue for therapeutic discovery. Previously, we used this approach to identify repurposed candidates for DMG; however, the final candidate had poor brain penetration, prompting us to discover novel compounds with better brain penetration. To apply it to novel compound discovery, we need the expression profiles of all library compounds, which is impractical for millions of compounds. To overcome this, we have developed a platform, Gene expression profiles Predictor on chemical Structures (GPS), that incorporates machine learning algorithms which leverage existing drug-induced gene expression profiles to predict gene expression based on compound structure. methods. DMG RNA-Seq samples were acquired from St. Jude Children’s Research Hospital and Children’s Brain Tumor Network (CBTN). We developed deep learning autoencoder to search reference normal tissues from Genotype-Tissue Expression (GTEx). A DMG meta-signature was created and fed into GPS to predict drug candidates from the Enamine CNS library, seven of which were experimentally tested in vitro and the most promising one subsequently validated in vivo. Results. Cell proliferation analyzed by MTS assay showed three compounds with IC50< 50 µM in K27M-mutant DMG cell lines (SF8628, DIPG007, SU-DIPG36). Toxicity study showed no adverse effects in the mice treated with 100-200 mg/kg of the most promising compound (IC50 = 1.9 µM in DMG cells). Conclusion. Our novel computational framework leverages deep learning to fill the gap in drug discovery in DMG. Work is underway to determine antitumor activity, brain penetration (via HPLC) and survival benefit in the mice bearing DMG PDX treated with the lead compound.
DDDR-34. A SYSTEMS MEDICINE PLATFORM FOR INDIVIDUALIZED TREATMENT OF GLIOBLASTOMA
Authors: Skaga Erlend , Naderi Pourya , Halldorsson Skarphedinn , Sandberg Cecilie J , Hide Winston , Vik-Mo Einar O
Published: November 2024

Glioblastoma is an aggressive brain cancer characterized by complex intertumoral heterogeneity. Yet, no methods have successfully stratified patients for effective individualized treatments. We aimed to use a systems medicine approach to individualize treatments for patients. From 27 patients undergoing surgery for either a newly diagnosed or a progressive glioblastoma, we collected biopsies and cultured the cells as spheroids. Drug sensitivity testing for >500 drugs from the FDA-approved oncology collection was performed. Drug efficacy was quantified using a modified area under the dose-response curve (Drug Sensitivity Score, DSS), and individualized by normalizing the DSS to the drug response in bone marrow cells from healthy donors (selective DSS, sDSS). All samples were assayed by WES, WGS, and RNA-sequencing. We found that glioblastomas can be stratified into three DSS groups. These were associated with expression of genes both known (e.g. ALDH1A1), and not known (e.g. VRK2) to be linked to drug resistance. By unsupervised clustering of sDSS, we found a robust patient stratification primarily driven by drug sensitivity to four groups of targets: i) EGFR, ii) FGFR/PDGFR/VEGFR, iii) MDM2 and iv) MEK/ERK. We found differentially expressed genes (N = 20-90 genes, varying by group) between the responders and non-responders in each group. We explored differential pathway activity between the responders and non-responders in each group to correlate drug responses to transcriptional networks to inform underlying disease mechanisms. The transcriptional networks further provide a molecular basis for drug predictions for additional treatment prioritizations. We conclude that our platform can stratify glioblastomas into subgroups, inform the underlying biology of drug sensitivity, and prioritize treatments for patients. Clinical utility is currently under evaluation in a formal trial.
DDDR-35. THERAPEUTIC STRATEGIES FOR DIFFUSE MIDLINE GLIOMA: INSIGHTS FROM HIGH-THROUGHPUT COMBINATION DRUG AND RADIATION SENSITIZATION SCREENING
Authors: Faisal Syed M , Yadav Monika , Gibson Garrett R , Klinestiver Adora T , Roy Anuradha , Koschmann Carl , Weir Scott J , Bossmann Stefan H , Yadav Viveka Nand
Published: November 2024

Diffuse midline gliomas (DMGs) are the most aggressive pediatric high-grade gliomas. Over 85% DMGs harboring the H3K27M mutation in histone genes H3F3A (H3.3) and H3C2 (H3.1). H3K27M mutation disrupts epigenetic regulation by inhibiting PRC2, causing loss of H3K27 trimethylation and oncogenic gene expression. Presently, there are no effective therapies for DMG, and 95% of the patients die within 1.5 years of diagnosis. Thus, there is an urgent need to identify novel therapeutic strategies targeting H3K27M oncohistone. To assess the H3K27M mutation’s vulnerability, we used paired isogenic H3K27M-mutated and CRISPR-corrected H3M27K (H3-WT) primary DMG cell lines derived from thalamus (BT-245) and pons (DIPGXIIIP). We performed comprehensive single-agent high-throughput screens (HTS) with 1,520 FDA-approved drugs and further assessed drug combinations of ONC201 with the 86 most promising drugs from the HTS. A third combination experiment evaluated radio-sensitizing potential, where most effective top-six drugs (A-F) were tested in combination with radiation therapy across an expanded panel of patient-derived DMG cell cultures. To test drug efficacy in vivo, we developed a genetically engineered isogenic mouse model (GEMM) of DMGs using intrauterine electroporation (IUE) with DNp53/PDGFRA/H3.3K27M (PPK) and DNp53/PDGFRA/H3.3WT (PPW) genetic alterations. Our initial single-agent HTS screening identified 86 drugs with significantly higher cytotoxicity, specifically against H3K27M-mutated DMG cell lines. Combination HTS of the top six drugs revealed that drug E displayed significantly synergistic cytotoxicity with ONC201. We also evaluated drugs A-E in combination with radiation in both human and mouse H3K27M-mutated DMG cell lines. Drugs D and E showed selective radiosensitivity in both human and mouse H3K27M-mutated DMG cell lines. Preliminary findings also suggested drug D acts as an anti-invasive agent. Our findings identify novel drugs via HTS that enhance ONC201 efficacy and act as radiation sensitizers in DMGs. Future studies will test these compounds with ONC201 and radiation in our in vivo IUE-mediated H3K27M mouse model.
DDDR-45. INVESTIGATING TEMOZOLOMIDE RESISTANCE IN GLIOBLASTOMA USING A CLINICALLY RELEVANT DOSING REGIMEN
Authors: Kumar Harshita , Dhawan Andrew
Published: November 2024

The standard of care of management for glioblastoma, the most common primary malignant brain tumor in adults, involves maximal safe surgical resection followed by adjuvant chemoradiotherapy and six cycles of adjuvant temozolomide (TMZ). Approximately half of all treated patients develop chemoresistance to TMZ. The evolution of chemoresistance to temozolomide in vitro has historically involved continuous exposure to drug, as opposed to clinical dosing schedules, which involve five days of treatment followed by 23 days of recovery. Thus, in this study, we examined the emergence of chemoresistance to TMZ in vitro, using a clinical dosing regimen. Temozolomide dose response to RN1, an MGMT promoter unmethylated, IDH-wildtype, patient-derived glioblastoma cell line, was determined using cell titer glo. Cells were treated with TMZ for five days, followed by 23 days of recovery, in cycles. In each subsequent cycle, the dose of TMZ used was adjusted to previous cycle’s IC50, the concentration at which 50% of cell growth is inhibited. This protocol was repeated over three rounds. Cells treated with TMZ, as compared to the DMSO-treated control population, gradually acquired chemoresistance with a continuous increase in IC50. Our protocol therefore highlights how a clinically relevant dosing regimen may help capture the trajectory by which chemoresistance emerges, also allowing for the exploration of the molecular mechanisms underlying this phenomenon.
DDDR-46. TARGETING TRANSGLUTAMINASE 2 (TGM2) ENHANCES SENSITIVITY OF GLIOBLASTOMA CELL LINES TO RADIOTHERAPY AND TEMOZOLOMIDE
Authors: Lan Katherine , Jamali Fatemeh , April Vincent , Sabri Siham , Abdulkarim Bassam
Published: November 2024

Glioblastoma (GBM), the most aggressive and common primary brain tumor in adults, remains highly resistant to conventional therapeutics, including radiation therapy (RT), largely due to its molecular heterogeneity. Few biomarkers have been identified that successfully guide or predict treatment response. Transglutaminase 2 (TGM2), a ubiquitous multifunctional enzyme involved in numerous signal transduction pathways related to tumorigenesis, has recently been suggested to drive chemoradioresistance. Here, we investigate the effects of disrupting TGM2 by pharmacologic inhibition or CRISPR knockout (TGM2-KO) on GBM cell’s response to RT and Temozolomide (TMZ) chemotherapy. Using western blotting and clonogenic assays, we show that the allosteric TGM2 inhibitor, GK921, stabilizes p53 expression and impedes reproductive ability at IC50 and IC25 concentrations. TGM2-KO and GK921 (at IC10 and lower) sensitized GBM cell lines to RT with almost equivalent efficacy, resulting in a 2- to 3-fold suppression of clonal expansion compared to scramble controls or irradiation alone. We also demonstrate increased sensitivity of GBM cell lines to TMZ upon inhibition of TGM2 by GK921. Our findings indicate that the use of TGM2 inhibitors, such as GK921, could enhance the efficacy of RT and the potency of TMZ, positioning TGM2 as a promising therapeutic target that may improve standard treatment of GBM cells expressing TGM2.
EOLP-02. END-OF-LIFE CHALLENGES IN NEURO-ONCOLOGICAL PATIENT CARE: A YOUNGNOA SURVEY
Authors: Lazaridis Lazaros , Pepper Niklas , Agkatsev Sarina , Bodensohn Raphael , Berg Rebecca , Seliger Corinna , Hau Peter , Platten Michael , Combs Stephanie , Mildenberger Iris , Müther Michael , Kebir Sied
Published: November 2024

BACKGROUND

Malignant brain tumors inevitably relapse, almost always causing significant functional and neurological impairments. Thus, palliative care is crucial in managing individuals with malignant brain tumors. It is essential for neuro-oncologists to be well-prepared to openly communicate about and meet the palliative needs of these patients. With this survey, we sought to evaluate palliative care practices in Germany and their impact on the treatment of neuro-oncological patients.

METHODS

We conducted an anonymous, interdisciplinary survey targeting palliative care practices among neuro-oncologists in Germany, all members of the Neuro-oncology Working Group of the German Cancer Society. The questionnaire, designed in close coordination with board-certified palliative care specialists, was distributed to 450 physicians. It collected personal information and assessed respondents’ knowledge of and access to palliative care structures. The survey was conducted online from March 31 to April 30, 2023.

RESULTS

Ninety-two physicians completed the survey. Of these, 81 (88%) reported feeling comfortable with end-of-life conversations, while 11 (12%) did not. No significant differences were observed between the two subgroups regarding their level of medical education (p=0.7140), workplace (p=0.4966), sex (p=0.9999), medical specialty (p=0.5478), or region of practice (p=0.9999). However, those comfortable with end-of-life discussions had significantly more palliative care training either during specialty training (p=0.0475) or through active participation in palliative care courses (p=0.0254). Further detailed analysis is in progress.

CONCLUSIONS

The survey indicates that while the majority of participants are comfortable with end-of-life discussions, a clear correlation exists between their comfort level and the extent of palliative care training received. This highlights the critical need for enhanced and targeted palliative care education within neuro-oncology training programs to prepare physicians for the complex communication and care challenges in neuro-oncological palliation. Further analysis will continue to explore additional educational and systemic factors that could increase the quality of palliative care in neuro-oncology.
EPID-01. PEDIATRIC BRAIN TUMORS IN SUB-SAHARAN AFRICA:A SYSTEMATIC REVIEW AND META-ANALYSIS
Authors: Nyalundja Arsene Daniel , Kanmounye Ulrick Sidney , Karekezi Claire , Laeke Tsegazeab , Thango Nqobile , Balogun James A
Published: November 2024

OBJECTIVE

brain tumors are a global problem, leading to higher cancer-related morbidity and mortality rates in children. Despite the progressive though slow advances in neuro-oncology care, research, and diagnostics in sub-Saharan Africa (SSA), the epidemiological landscape of pediatric brain tumors (PBTs) remains underestimated. This study aimed to systematically analyze the distribution of PBT types in SSA.

METHODS

major databases and grey literature were searched for literature on PBTs in SSA published before October 29, 2022. A proportional meta-analysis was performed.

RESULTS

forty-nine studies, involving 2360 children, met the inclusion criteria for review; only 20 (40.82%) were included in the quantitative analysis. South Africa and Nigeria were the countries with the most abundant data. Glioma not otherwise specified (NOS) was the common PBT in the 4 SSA regions combined. However, medulloblastoma was more commonly reported in Southern-SSA(p=0.01) than in other regions. The prevalence and the overall pooled proportion of the 3 common PBTs was estimated at 46.27% and 0.41 (95%CI 0.32–0.50, 95% prediction interval [PI] 0.11–0.79), 25.34% and 0.18 (95%CI 0.14–0.21, 95%PI 0.06–0.40), and 12.67% and 0.12 (95%CI 0.09–0.15, 95%PI 0.04–0.29) for glioma-NOS, medulloblastoma, and craniopharyngioma, respectively. Sample size moderated the estimated proportion of glioma-NOS (p = 0.02). The highest proportion of craniopharyngiomas was in Western-SSA, and medulloblastoma and glioma-NOS in Central-SSA.

CONCLUSION

these findings provide insight into the trends of PBT types and the proportion of the top 3 most common tumors across SSA. Although statistical conclusions are difficult due to the inconsistency in the data. We identify critical areas for policy development and collaborations that can facilitate improved outcomes in PBTs in SSA. More accurate epidemiological studies are needed to better understand the burden of the disease and the geographic variation in their distribution, and to raise awareness in their subsequent management.
EPID-04. VESTIBULAR SCHWANNOMA IN PREGNANCY: A SYSTEMATIC REVIEW
Authors: Bartman Mason , Barake Carole
Published: November 2024

INTRODUCTION

Vestibular Schwannomas (VS) are intracranial tumors of the nervous system originating from peripherally myelinating Schwann cells. There are sparse reports of this tumor presenting in pregnant patients but many of the cardinal symptoms of pregnancy overlap with the presentation of VS. For this reason, we systematically reviewed reports of VS in pregnant patients to identify the most specific clinical symptoms to aid diagnosis of and address management considerations for this population.

METHODS

Our systematic review was performed according to PRISMA guidelines. The data extracted includes study characteristics, symptom presence and onset relative to tumor diagnosis, tumor size, treatment modality, complications, and maternal/fetal health outcomes. This data was analyzed for overlap with commonly presenting symptoms and current management trends.

RESULTS

Sixteen papers between 1967 and 2018 reported a total of 26 pregnant patients who met criteria for inclusion. The most common presenting symptoms were hearing loss (76.9%), ataxia (42.3%), headache (38.5%), and vomiting (38.5%). The symptoms that presented with the longest duration were dizziness/vertigo (145.33 weeks), tinnitus (155 weeks), and hearing loss (145.67 weeks). The most common complications were post-op facial paralysis (46.2%), hydrocephalus (23.1%), and post-op hearing loss (19.2%).

CONCLUSIONS

A heightened clinical suspicion for VS in pregnant patients is needed due to the large overlap of cardinal symptoms of pregnancy and VS presentation. The way pregnancy changes patients’ normal physiology should be considered when determining optimal management. We hope that this review will improve diagnostic accuracy and prevent complications in pregnant patients with VS.
EPID-22. MUTATIONAL SIGNATURE ASSOCIATED WITH HALOALKANE EXPOSURE ENRICHED IN FIREFIGHTERS IN THE ADULT GLIOMA STUDY
Authors: Cannataro Vincent , Bracci Paige , Taylor Jennie , McCoy Lucie , Rice Terri , Hansen Helen , Heffernan Annie , Wiemels Joe , Wiencke John , Wrensch Margaret , Claus Elizabeth
Published: November 2024

Using data from The Cancer Genome Atlas (TCGA) and Glioma Longitudinal Analysis (GLASS), we identified specific environmentally related mutational signatures in glioma including a signature associated with haloalkane exposure (SBS42) from the Catalogue of Somatic Mutational Signatures (COSMIC). Haloalkanes are widely used commercially including in flame retardants and fire extinguishants and are an intriguing finding given an observed increased glioma risk in firefighters. To validate our findings, we use new study participants with data on occupation (not available in either TCGA/GLASS) from the University of California, San Francisco Adult Glioma Study (AGS) to compare mutational signatures in tumors from 17 persons with glioma and documented occupational exposure to firefighting with those of 18 matched glioma patients without history of firefighting. Using whole exome sequencing, we identified environmental exposure signatures in tumor tissue from firefighters as well as in non-firefighters who had other relevant occupational exposure (e.g. auto/truck mechanic work). In these data, glioma is largely associated with aging and mutational signatures relating to endogenous mutational processes that correlate with age, such as spontaneous or enzymatic deamination of 5-methylcytosine. However, some gliomas have detectable signatures associated with exogenous mutational processes, such as SBS42 haloalkanes. Thus, we confirm detection of haloalkane signatures in persons likely highly exposed, i.e. long-term firefighters. Identifying exogenous mutational processes in cancers are important as they may inform public health intervention strategy to reduce mutagenesis and prevent cancer inception. Identifying occupational correlates with SBS42, associated with occupational exposure to haloalkanes, will pinpoint occupational hazards that may be avoidable. This is especially important for glioma and other cancers where exogenous mutagenesis is not well established.
EPID-24. OPTIMIZING PATIENT RECRUITMENT FOR BRAIN TUMOR STUDIES: LEVERAGING THE POWER OF GOOGLE ADS TO CONNECT WITH AFFECTED FAMILIES
Authors: Kakaizada Sofia , Bainbridge Matthew , Armstrong Georgina , Bondy Melissa
Published: November 2024

OBJECTIVE

We assessed the effectiveness of using Google Ads to recruit individuals with familial glioma into a genetic research study.

METHODS

We conducted a comparative analysis between two periods: March 1 to June 30, 2023 (with Google Ads) and March 1 to June 30, 2021 (without Google Ads). We targeted individuals searching for brain tumor information using Google Ads, directing them to a study landing page. We analyzed metrics such as advertisement clicks, impressions, click-through rate, and cost per click. Our eligibility criteria included families with at least two members having glioma, with one currently living with the condition, aged 18 or older, and residing in the United States.

RESULTS

The 2023 Google Ads campaign generated 7,228 clicks, 82,242 impressions, an 8.79% click-through rate, and a cost per click of $0.62. The number of interested individuals increased from 13 in 2021 (without Google Ads) to 35 in 2023 (with Google Ads), with 20 indicating they found the study through Google Ads. However, the increase lacked statistical significance (x2=1.48, p=0.22).

CONCLUSION

Google Ads enhanced our participant outreach and recruitment for the glioma study, although the results were not statistically significant. This approach shows promise for recruiting participants for rare disease research. We recommend that future studies consider longer durations and larger sample sizes to better assess its impact. Additionally, due to the prevalence of misinformation about familial glioma, we submitted and conducted a survey to the Society of NeuroOncology to evaluate the attitudes and beliefs of physicians and other healthcare professionals towards familial glioma. This survey aims to address misconceptions and improve understanding within the healthcare community.
IMMU-14. TRANS-SPECIES ANALYSIS OF REPLICATION-REPAIR DEFICIENT (RRD) MEDULLOBLASTOMA AND RESPONSE TO IMMUNE CHECKPOINT INHIBITION: AN IRRDC REPORT
Authors: Das Anirban , Fernandez Nicholas , Levine Adrian , Smith Kyle , Wang Evan , Galati Melissa , Aamir Zoya , Chung Jill , Negm Logine , Friedman Hope , O’Flaherty Katharine , Crump Owen , Trinh Quang , Nunes Nuno , Bianchi Vanessa , Stengs Lucie , Edwards Melissa , Stein Lincoln , Bouffet Eric , Taylor Michael , Northcott Paul , Ramaswamy Vijay , Hawkins Cynthia , Tabori Uri
Published: November 2024

BACKGROUND

Replication-repair deficiency (RRD) stemming from mismatch repair and polymerase proofreading gene defects (MMRD/PPD) lead to hypermutant childhood cancers, most frequently brain tumors. While medulloblastoma is reported, the clinical, genomic and immune landscape remains unknown.

METHODS

We analysed the genome, methylome, transcriptome (bulk, single-nuclei) and immune-microenvironment of the largest cohort of RRD-medulloblastoma patients enrolled by the International RRD Consortium and correlated these to clinical outcomes. RRD mice-models were used to preclinically assess response to immunotherapy. Results:

RESULTS

RRD-medulloblastoma (n=43) were enriched for anaplasia (61%) and localised disease (77%). Methylation/nano-string-based subgrouping failed to classify 40%, while the remaining clustered with the SHH-subgroup. Copy-number changes were notably infrequent (<20%). All tumors harboured hypermutation and microsatellite instability in contrast to non-RRD controls (p<0.0001). Pathogenic variants were frequent in POLE/POLD1 (80%), TP53 (48%) and SHH-pathway genes (PTCH1, SUFU, SMO: 56%). Interestingly, some tumors additionally had glioma-driver alterations (ATRX, NF1: ~50%), similar to RRD cerebellar glioblastoma, but distinct from both non-RRD medulloblastoma (n=791) and hemispheric glioblastoma (n=733) controls. Moreover, although bulk-transcriptome matched non-RRD SHH medulloblastoma, single-nuclei analyses suggested an earlier cell-of-origin potentially explaining the heterogenous phenotypes resulting from the driver mutations. Uniquely, immune analyses (gene expression and immunohistochemistry) demonstrated high intra-tumoral CD8 T-cell infiltration. Three-year progression-free survival was 60%. Outcome was worse for RRD-medulloblastoma harbouring TP53-mutation (p=0.04) and failing subgroup-classification (p=0.004). Nestin/Cre MSH2-/- POLE;p.S459F mice developing medulloblastoma recapitulated human disease and demonstrated response to anti-PD1 monotherapy. Recurrent/progressive human tumors including those harbouring TP53-mutations exhibited radiological responses to anti-PD1 monotherapy, which was associated with prolonged ongoing survival in comparison to those not treated with checkpoint-inhibitors (p=0.02).

CONCLUSIONS

Hypermutant RRD-medulloblastoma reveal heterogenous phenotypes due to unique spectrum of driver mutations and an early cell of origin. Their immune-hot microenvironment allows successful salvage treatment with checkpoint-inhibitors for those failing chemo-radiation, including the high-risk SHH/TP53-mutant and unclassified subgroups.
IMMU-16. ANTI-VEGF TREATMENT EFFECT AGAINST GLIOMA IS IMMUNE DEPENDENT AND MEDIATED BY ENHANCED T CELL ACTIVITY
Authors: Maire Cecile , Mohme Malte , Fita Krystian , Reetz Merle , Heinemann Sarina , Tolosa Eva , Alawi Malik , Casar Christian , Spohn Michael , Gempt Jens , Westphal Manfred , Lamszus Katrin
Published: November 2024

Immunotherapy trials in glioblastoma patients increasingly avoid immunosuppressive steroids and consider bevacizumab as alternative anti-edema treatment. Since VEGF is also a potent immunosuppressive factor, we explored the dimension and mechanisms of immune-mediated effects of anti-VEGF treatment. Murine glioma cells were injected intracerebrally into C57BL/6 wild-type mice or immunodeficient Pfp/Rag2 knockout mice and animals were treated with B20 (anti-murine VEGF) or dexamethasone. Immune cells were profiled by flow cytometry, and RNAseq was performed on sorted tumor and immune cells at different timepoints. B20 prolonged the survival of immunocompetent mice but not of Pfp/Rag2 knockout mice, indicating that the immune system is essential for its effect. At an early timepoint when controls became symptomatic, B20 “early” tumors (B20-ea) showed increased infiltration with T cells and myeloid cells, and decreased vascularization, whereas B20 tumors at the survival endpoint resembled IgG-controls. Gene expression in B20-ea tumor cells was dominated by hypoxia, neural development, invasion, TGF-β, Notch and Wnt signatures as well as concerted upregulation of Kmt2 H3K4 methyltransferases. In CD11b+ myeloid cells from B20-ea tumors, M1 hallmark genes and T cell activation genes were upregulated, while M2 genes were downregulated. Deconvolution revealed a transient shift towards pro-immune microglia/macrophages as well as increased NK cells and DCs. In CD8+ and CD4+ T cells, B20 increased the expression of S1pr1 and α/β TCR genes. The proportion of progenitor-like exhausted CD8+ cells, which are responsive to PD-1 blockade, was increased in B20-ea. In CD4+ cells, B20 caused skewing towards TFH, while dexamethasone increased TH2 cytokine expression. Depletion experiments demonstrated that CD8+ and CD4+ T cells but not NK cells were necessary for the survival-prolonging effect of B20. To conclude, anti-VEGF therapy has significant immunostimulatory effects which are, however, largely transient, so that an early treatment window of opportunity may exist during which it could actively support immunotherapy.
IMMU-31. DAMAGE RESPONSE FROM SYSTEMIC RNA VACCINATION RESTORES HUMORAL IMMUNITY IN GLIOBLASTOMA
Authors: Moor Rachel , Aghaee Mahya , Carrera-Justiz Sheila , Qdaisat Sadeem , Xie Chao , Soni Dhruvkumar , von Roemeling Christina , DeVries Anna , Wummer Brandon , Weidert Frances , Chardon-Robles Jonathan , Ligon John , Castillo Paul , Silver Natalie , Kline Cassie , Prados Michael , Mueller Sabine , Hwang Eugene , Rahman Maryam , Ghiaseddin Ashley , Mitchell Duane , Seligson Nathan , Mendez-Gomez Hector , Moore Helen , Sayour Elias
Published: November 2024

Therapies against glioblastoma (GBM) remain stymied by poor penetration across the blood-brain barrier (BBB) and systemic immunotolerance. These outcomes necessitate development of therapies simultaneously targeted to tumors while engineering peripheral immunity to co-localize for synergistic responses. We developed RNA loaded lipid particles (LPs) to simultaneously function as inducers of cytotoxic responses in the GBM tumor microenvironment (TME) and as systemic activators of peripheral immunity. RNA-LP mediated response was studied in mice bearing KR158b tumors and in canines and humans with spontaneous glioma and glioblastoma respectively. We found that RNA-LPs could localize to the brain TME of animals bearing murine gliomas and rapidly upregulate damage associated signaling pathways including p53-CDKN2A. This correlates with increased gene signatures for complement and proteosome processing. Simultaneously, in the periphery, RNA-LPs increase integrin expression on activated T cells and ICAM expression in brain tumors helping steer T cell translocation across the BBB. In canines with malignant gliomas, response to RNA-LPs correlated with increasing tumor size suggesting pseudoprogression. Similar to murine glioma, canine gliomas harvested within 48h of vaccine administration demonstrated rapid increases in complement and p53 pathway activation. In one human patient treated with RNA-LPs per NCT04573140 (PNOC020 trial), we demonstrate biopsy confirmed pseudoprogression with increases in p53 pathway signaling and complement activation. In post-treatment tumor biopsy samples, there was increased hyperexpanded post-infusion intratumoral IgH clones. Systemic administration of RNA-LP elicits damage response in the TME that predisposes complement activation and humoral immunity. Coupled with peripheral recruitment of T cells that can translocate across the BBB, RNA-LPs elicit potent bi-directional adaptive immunotherapy against GBM.
IMMU-39. CAR T CELLS TARGETING ICAM-1 SHOW A SURVIVAL BENEFIT IN BOTH SYNGENEIC AND XENOGRAFT GLIOMA MOUSE MODELS
Authors: Soballa Melanie , Mastall Maximilian , Villars Danielle , Hänsch Lena , Mayoux Maud , Tugues Sonia , Weller Michael , Roth Patrick
Published: November 2024

BACKGROUND

Chimeric antigen receptor (CAR) T-cell therapy, while effective against hematological malignancies, has faced significant hurdles in its application to solid tumors. Challenges in CAR T-cell therapy for glioblastoma include the immunosuppressive tumor microenvironment, the limited infiltration of CAR T-cells into the tumor, heterogeneous target expression and antigen escape. In this study, we focused on targeting Intracellular adhesion molecule-1 (ICAM-1), a protein expressed on both glioma cells and tumor-associated cells like macrophages and endothelial cells.

METHODS

Glioblastoma and normal brain tissue microarray sections (TMA) were immunohistochemically analyzed for ICAM-1 expression. Second-generation human and murine ICAM-1-targeting CAR T cells were generated by lentiviral or retroviral transduction of T cells from healthy human donors or murine splenocytes. Their efficacy was evaluated in co- culture assays with human and murine glioma and endothelial cell lines. Syngeneic and xenograft orthotopic glioma mouse models were used to assess the in vivo activity of CAR T cells. Ex vivo analysis of these tumors included examination of changes in the tumor microenvironment using high-dimensional flow cytometry.

RESULTS

Immunohistochemical staining of TMA revealed a significant upregulation of ICAM-1 in human glioblastoma tissue compared to normal brain tissue. Single-cell RNA sequencing data from glioblastoma specimens showed a high level of ICAM-1 expression in tumor- associated macrophages. Human and murine ICAM-1-targeting CAR T cells displayed strong lysis of ICAM-1-expressing glioma and endothelial cells in vitro. Intratumoral application of CAR T cells resulted in a survival benefit in both syngeneic and xenograft glioma mouse models. Ex vivo analysis of the tumor microenvironment revealed treatment-induced changes from our CAR T cell therapy and indicates potential for further enhancements.

CONCLUSION

Our study demonstrates that ICAM-1-targeting CAR T cells improve survival in human and murine glioma mouse models. Flow cytometry of the tumor microenvironment reveals therapy-induced changes, for future improvements of the CAR T cell therapy.
IMMU-41. GBM PLATELET HYPERACTIVITY DRIVES THE IMMUNOSUPPRESSIVE TME IN A SEX-DEPENDENT MANNER
Authors: Sloan Anthony , Bukenya George , Tack Liza , Horbinski Craig , Khorana Alok , Gupta Anirban Sen , Nieman Marvin , Cameron Scott , Lathia Justin
Published: November 2024

Cancer-related thrombosis is the second leading cause of death for cancer patients, including those with glioblastoma (GBM), the most common primary malignant brain tumor. Patients with GBM have a 30% risk of venous thromboembolism. Moreover, sex biases are well established in GBM, with men 1.6-fold more likely to develop GBM and exhibiting a poorer prognosis than females. GBM is extremely difficult to treat due to its highly immunosuppressive tumor microenvironment (TME), often infiltrated with suppressive myeloid populations and a reduction in T-cells intratumorally and systemically. Our group has recently demonstrated these sex-biases in survival are due to differences in the immune cell populations making up the TME. Despite these findings, there is limited information as to how a hyper-thrombotic state contribute to the immunosuppressive TME. Additionally, the role that sex biases play in these mechanisms has not been explored. Our previous work demonstrated that thrombin, a major platelet activator through PAR1 and PAR4 receptor signaling, is secreted from cancer stem cells into the tumor microenvironment. We now show that GBM patient have elevated levels of the thrombin-antithrombin complex and have increased PAR4 receptor mediated platelet activation. Similarly, we show that tumor bearing mice have elevated PAR4 receptor mediated platelet activation relative to non-tumor bearing mice. We further demonstrate pharmacologically targeting the thrombin-PAR4 signaling axis in murine GBM models prolongs survival in females but has not affect in males by preventing female platelet hyperactivity and subsequently increasing the number and function of tumor infiltrating CD8+ T-cells. These findings demonstrate how activated platelets interact and regulate immune cell populations in GBM. These results suggest that the hyper-thrombotic state seen in many GBM patients simultaneously contributes to the immunosuppressive TME. In addition, these results identify therapeutic strategies to leverage the platelet hyperactivity seen in GBM by hyperactive thrombin-PAR4 for sex-dependent therapeutic purposes.
IMMU-42. UNRAVELING THE ROLE OF NLRX1 IN GLIOBLASTOMA TUMOR MICROENVIRONMENT
Authors: meena Durgesh , Rajkhowa Sushmita , Jha Sushmita
Published: November 2024

•Gliomas are primary brain tumors that develop from glial cells within the central nervous system (CNS) and are among the deadliest human cancers. Glioblastoma (GBM) is the most aggressive glioma. Innate immune cells such as microglia and macrophages account for >50% of the cellular population within the GBM microenvironment. Innate immune cells express pattern recognition receptors (PRRs). NLRX1 is a PRR that regulates diverse signaling pathways and cellular processes including antiviral signaling, ROS production, apoptosis, autophagy, metabolic homeostasis, etc. Additionally, the tumor-suppressive and tumor-promoting functions of NLRX1 have been observed in many cancer types. For example, the tumor-suppressive role of NLRX1 has been observed in colitis-associated carcinogenesis, pancreatic cancer, and primary breast cancer. In contrast, the tumor-promoting role of NLRX1 was found in basal-like and metastatic breast carcinoma. Hence, the effect of NLRX1 on cancer may be context-dependent on cancer type or cell type aided by differences in the microenvironment. Further, how NLRX1 regulates GBM pathophysiology remains largely unexplored. This study aims to determine the expression pattern of NLRX1 in GBM cells and GBM-associated innate immune cells and investigate how NLRX1 expression regulates various cellular processes in GBM cell lines to regulate GBM pathophysiology. We report that NLRX1 is differentially expressed in GBM cell lines, GBM-associated innate immune cells, and glioma patient tissues. si-RNA-mediated silencing of Nlrx1 decreases the ability of the GBM cell line, LN-229 to proliferate and migrate. Further, Nlrx1-/- GBM cells show increased tunneling nanotube (TNT) formation capabilities. TNTs help in metabolic homeostasis maintenance by enabling the exchange of subcellular organelles such as mitochondria and endoplasmic reticulum. Nlrx1-/- GBM cells exhibit attenuated ability to form 3D spheroids. This research will aid the understanding of GBM pathophysiology, leading to novel diagnostic/prognostic markers and the discovery of signaling pathways that, in turn, may help create better GBM therapy approaches and improve overall survival.
IMMU-52. A NOVEL MHC-INDEPENDENT MECHANISM FOR CD8+ T CELL KILLING
Authors: Lerner Emily , Woroniecka Karolina , Wilkinson Daniel , Mohan Aditya , Lorrey Selena , Waibl-Polania Jessica , Wachsmuth Lucas , Hoyt-Miggelbrink Alexandra , Jackson Joshua , Cui Xiuyu , Sampson John , Patel Anoop , Khasraw Mustafa , Gunn Michael , Fecci Peter
Published: November 2024

The long-accepted paradigm for both cellular and antitumor immunity relies upon tumor cell kill by CD8+ T cells recognizing cognate antigens presented in the context of target cell major histocompatibility complex class I (MHC I) molecules. Likewise, a classically described mechanism of tumor immune escape is tumor MHC-I downregulation. Here, in contrast to the decades old model of T cell immunity, we instead report that CD8+ T cells maintain the capacity to kill tumor cells that are entirely devoid of MHC-I expression. This capacity proves to be dependent instead on interactions between T cell NKG2D and tumor NKG2D ligands (NKG2DL), the latter of which are highly expressed on MHC-loss variants. Necessarily, tumor cell kill in these instances is antigen-independent, although prior T cell antigen-specific activation is required and can be furnished by myeloid cells or even neighboring MHC-replete tumor cells. In this manner, adaptive priming can beget innate killing. These mechanisms are active in vivo in mice, as well as in vitro in human tumor systems, and are obviated by NKG2D knockout or blockade. These studies challenge the long-advanced notion that downregulation of MHC-I is a viable means of tumor immune escape, and instead identify the NKG2D/NKG2DL axis as a therapeutic target for enhancing T cell-dependent anti-tumor immunity against MHC loss variants.
IMMU-58. BCAT1 TARGETED METABOLIC REPROGRAMMING PLAYS CRITICAL ROLES IN MODULATING MYELOID DERIVED SUPPRESSOR CELL FUNCTION IN GLIOBLASTOMA
Authors: Jackson Christina , Ning Yi , Jones Kate , Simon Celeste , Bailis Will
Published: November 2024

A key component that has limited the efficacy of immunotherapy in glioblastoma (GBM) is the significant infiltration of immunosuppressive myeloid cells. Our previous work characterized myeloid derived suppressor cells (MDSCs) unique to GBM that drive tumor growth and immune suppression. Transcriptomic and flow cytometric analyses demonstrated that the most induced programs in these MDSCs are dominated by metabolic and mTOR pathways. Therefore, we aimed to understand the role of metabolic reprogramming in MDSC differentiation and immunosuppressive function. Using single cell RNA sequencing, we identified overexpression of enzymes and transporters involved in branched-chain amino acid (BCAA) metabolism, notably branched chain aminotransferase 1 (BCAT1), the first enzyme in the metabolic pathway. Intriguingly, this was only found in specific populations of early and monocytic MDSCs (E-MDSCs, M-MDSCs), and not polymorphonuclear MDSCs (PMN-MDSCs). Using established MDSC modeling systems, we found that M-MDSC differentiation and T cell suppressive function are dependent on BCAAs and can be hindered by pharmacological inhibition of BCAT1 activity or genetic knockout of BCAT1. We also establish that the influence of BCAA on M-MDSC function is specifically reliant on the BCAT1-mediated step of BCAA metabolism. To determine the underlying mechanism driving BCAT1’s impact on M-MDSC function, we evaluated the activity of signaling pathways known to be critical to M-MDSCs including the mTORC1 pathway. We found that the impact of BCAA and BCAT1 activity on M-MDSC function is abrogated by inhibition of mTORC1 pathway with reduction in M-MDSC differentiation and activity. Consistent with our single cell RNA sequencing analysis, modulation of BCAA levels and BCAT1 activity had no impact on PMN-MDSCs. Our results underscore the critical role of BCAT1 in preferentially modulating M-MDSC activity through mTORC1 signaling. Our finding paves the way for discovery of a targetable therapeutic approach to harness immunometabolism in myeloid cells to develop novel immune therapies.
IMMU-63. MESSENGER RNA CHALLENGE PREDICTS CANCER IMMUNOGENICITY AND RESPONSE TO CHECKPOINT INHIBITORS
Authors: Castillo Paul , Ogando-Rivas Elizabeth , Geffrard Hilary , Pepe Alfonso , Nguyen Duy , Pedro Diego , Zhang Dingpeng , DeVries Anna , Qdaisat Sadeem , Grippin Adam , Rahman Maryam , Weidert Frances , Milner Rowan , Huang Jianping , Silver Natalie , Ligon John , Carrera-Justiz Sheila , Mitchell Duane , Mendez-Gomez Hector , Sawyer Gregory , Sayour Elias
Published: November 2024

BACKGROUND

Checkpoint inhibition has emerged as a promising cancer therapeutic approach. Checkpoint inhibitors (CIs) function by overcoming the adaptive T cell exhaustion induced by solid tumor microenvironment including brain tumors, particularly in the neoadjuvant setting. Unfortunately, not every patient who receives CIs will unlock effective antitumor immunity. Objectives: Microsatellite instability and high mutational burden are considered key criteria to predict response to CIs. However, only a minority of patients will fulfill these criteria suggesting the need to develop innovative technologies to identify CI responsive patients.

METHODS

To determine whether glioma tumors will respond to CIs, we have developed a novel multilamellar mRNA-lipid particle tool to predict response ex vivo. Messenger RNA is complexed into multilamellar lipid particles to form aggregates (RNA-LPAs) to induce pathogen recognition receptor signaling in tumor cells to define an inflammatory profile as an indirect predictor to CI response.

RESULTS

In naïve mice, we found that multilamellar RNA-LPAs induce activation of Type I IFN system as supported by decreased secretion of IFN-α in MyD88 KO mice compared with wild type mice. We next selected murine glioma cell lines with known response profile to CIs (responders – GL261 and SMA560 vs non-responders – KR158b and CT2A). Prior to evaluation of cytokine profiling, successful uptake of RNA-LPAs was achieved in all cell lines. In 2D cell lines cultures and their corresponding 3D tumor spheroids, we demonstrated that treatment of CI responsive murine glioma models showed a differential cytokine signature (increased secretion of IFN-β/IL-6/CCL4 versus non-responsive models).

CONCLUSION

We identified a unique inflammatory signature after ex vivo RNA-LPAs challenge that correlates with checkpoint blockade activity. These findings allow for creation of a diagnostic assay to quickly assess tumor immunogenicity, allowing for informed immunotherapeutic treatment.