bluuebunny/crossref_metadata_2025 huggingface dataset:
IMMU-11. NLRP3+ TUMOR-ASSOCIATED MYELOID CELLS ARE ENRICHED IN ASTROCYTIC GLIOMAS AND REPRESENT A THERAPEUTIC VULNERABILITY
Authors: Chandramohan Vidya , Stevenson Kevin , Yu Yen-Rei Andrea , Reitman Zachary , He Yiping , McLendon Roger , Osorio Cristina , Gregory Simon , Lipp Eric , Desjardins Annick , Friedman Allan , Nair Smita , Patel Anoop , Bigner Darell , Ashley David
Published: November 2023

BACKGROUND

Tumor-associated myeloid cells (TAMs) are known drivers of immunosuppression and glioma progression. Hence novel approaches for repolarizing TAMs from a protumorigenic to an antitumorigenic phenotype is an active area of investigation. While single-cell RNA sequencing (scRNA-seq) studies have characterized glioma TAMs in great detail, their uniqueness or similarity to TAMs in other tumors remains unknown. Cross-comparison of glioma TAMs with TAM subsets from other tumor types will aid in identifying novel TAM-targeted immunotherapies.

METHODS

We performed scRNA-seq of ~26K myeloid cells from nine patients with high-grade astrocytoma (n=3) and oligodendroglioma (n=6). The scRNA-seq findings were validated using TCGA RNA-seq data, public scRNA-Seq data, and immunohistochemistry (IHC) analysis.

RESULTS

The TAM clusters in gliomas predominantly exhibited a microglia-specific gene signature, while macrophage and monocyte clusters were also identified. Utilizing canonical TAM markers, we identified three major TAM subtypes, SPP1+ regulatory, FOLR2+ tissue-resident, and NLRP3+ inflammatory, enriched in astrocytomas. A gene set enrichment analysis of the three TAM subtype genes confirmed their enrichment in astrocytomas (IDHMut-non-codel) (P=0.0005; normalized enrichment score [NES]=1.79) in the TCGA bulk RNAseq data from IDH1-mutant LGGs. Investigation of the three TAM subtype markers in public scRNA-seq data confirmed their enrichment in immune/myeloid clusters across multiple glioma types (gangliogliomas, pilocytic astrocytomas, astrocytomas, diffuse midline gliomas, and glioblastomas). Finally, IHC analysis of 14 astrocytomas demonstrated regional variation in NLRP3 and FOLR2 expression in all cases, with a trend toward an inverse association between NLRP3 and FOLR2 expression.

CONCLUSIONS

1) Astrocytomas (IDHMut-non-codel) comprise TAM subsets common across multiple tumor types. 2) The FOLR2+ TAMs predict favorable outcomes, while the NLRP3+ TAMs are immunosuppressive and predict adverse outcomes in breast cancer. Given the inverse expression of NLRP3 and FOLR2 in astrocytomas, we hypothesize that NLRP3 TAMs+ are immunosuppressive and a potential immunotherapeutic target in astrocytomas.
IMMU-15. INTERPLAY BETWEEN ATRXAND IDH1 MUTATIONS GOVERNS INNATE IMMUNE RESPONSES IN DIFFUSE GLIOMAS
Authors: Whitfield Benjamin , Hariharan Seethalakshmi , Pirozzi Christopher , Waitkus Matthew , Brown Michael , Bowie Michelle , Irvin David , Roso Kristen , Fuller Rebecca , Hostettler Janell , Dharmaiah Sharvari , Gibson Emiley , Briley Aaron , Mangoli Avani , Fraley Casey , Shobande Mariah , Stevenson Kevin , Zhang Gao , Malgulwar Prit Benny , Roberts Hannah , Roskoski Martin , Spasojevic Ivan , Keir Steve , He Yiping , Castro Maria , Huse Jason , Ashley David
Published: November 2023

Stimulating the innate immune system has been explored as a therapeutic option for the treatment of gliomas. Inactivating mutations in alpha-thalassemia retardation X-linked (ATRX) are defining molecular alterations in IDH-mutant astrocytomas and have been implicated in dysfunctional immune signaling. However, little is known about the interplay between ATRX loss and IDH mutation on innate immunity. To explore this interaction, we used both CRISPR and the RCAS/tva system to generate murine models of ATRX-deficient glioma, in the presence and absence of the IDH1 R132H mutation. We found that ATRX-deficient glioma cells were exquisitely sensitive to dsRNA-based innate immune agonism, displaying increases in inflammatory gene expression and profound cytokine release in vitro, while mice bearing ATRX KO tumors displayed increased T-cell infiltration and improved survival. The presence of IDH1 R132H dampened baseline expression of key innate immune genes and cytokines, with genetic and pharmacological inhibition of IDH1 R132H partially rescuing this suppression. Despite the suppression observed at baseline, IDH1 R132H expression did not interfere with the ATRX KO-mediated sensitivity to dsRNA agonism. These results demonstrate that ATRX loss primes cells for recognition of and activation against dsRNA, while IDH1 R132H reversibly masks this priming. Thus, this study suggests that innate immunity is a potential therapeutic vulnerability of astrocytoma. Further studies are in progress to validate the influence of ATRX loss on immune signaling and tumor-immune coevolution within human tumors.
IMMU-17. INDUCING IMMUNE RESPONSE WITH FLASH AND CONVENTIONAL DOSE-RATE RADIATION IN DIFFUSE MIDLINE GLIOMA (DMG)
Authors: Gartrell Robyn , Minns Hanna , Padilla Oscar , Wei Hong-Jian , Webster-Carrion Andrea , Tazhibi Masih , McQuillan Nicholas , Zhang Xu , Gallitto Matthew , Yeh Rebecca , Zhang Zhiguo , Szalontay Luca , Pavisic Jovana , Garty Guy , Garvin James , Canoll Peter , Vanpouille-Box Claire , Menon Vilas , Olah Marta , Rabadan Raul , Wu Cheng-Chia
Published: November 2023

Diffuse Midline Glioma is a universally fatal inoperable pediatric brain tumor associated with H3K27M mutation and median survival of 9-15 months. Radiation therapy (RT) is the primary treatment, extending life by only three months. Conventional dose-rate RT (2Gy/min, CONV) can induce an immune response with type 1 interferon (IFN1) in multiple cancers including adult brain tumors. Ultra-fast dose-rate RT (90Gy/second, FLASH) has comparable tumor control to CONV with decreased toxicity, however, evaluation of immune response is limited. Using an orthotopic syngeneic model of brainstem DMG, we performed single-cell RNA sequencing (scRNA-seq) on CD45+ immune cells isolated from tumors four days post 15Gy FLASH or CONV RT, and compared to unirradiated tumor. We performed flow cytometry at day 4 and day 10 post-RT. ScRNA-seq reveals 33,308 immune cells in 17 unique clusters. Microglia (MG) make up 73.8% and non-resident myeloid cells make up 7.9% of cells and include macrophages (MAC), dendritic cells (DC) and Monocytes (MONO). Flow at day 4 and day 10 show no significant difference in proportion of immune cell subtypes comparing FLASH, CONV and tumor. With differential gene expression, FLASH and CONV provoke a similar inflammatory and IFN1 response in MG while in MACs and DCs IFN1 pathway expression is increased in CONV compared to FLASH (p< 0.001 for both), confirmed by flow at day 4 using IFNAR1 expression (MACs p< 0.05, DCs p< 0.01). Flow at day 10 post-RT shows increased IFNAR1 expression in MACs in both CONV and FLASH compared to tumor (p< 0.0001) while day 10 IFNAR1 in DCs is similar in all three groups. In summary, while immune proportions are similar comparing different dose rates of RT, IFN1 is differentially expressed in CONV compared to FLASH at day 4 in MACs and DCs, while this response at day 10 is similar comparing dose rates.
IMMU-19. MUTANT ISOCITRATE DEHYDROGENASE 1 IN GLIOMA CAUSES A REDUCTION IN ADENOSINERGIC PATHWAY SIGNALING WITHIN THE TUMOR MICROENVIRONMENT
Authors: McClellan Brandon , Dabaja Ali , Banerjee Kaushik , Zhu Ziwen , Barissi Marcus , Oh Paul , Wei Abraham , Lowenstein Pedro , Castro Maria
Published: November 2023

Glioma is one of the most aggressive cancers and represents approximately 80% of malignant brain tumors. The majority of CNS World Health Organization (WHO) grades 2-3 gliomas and a subset of high-grade gliomas (CNS WHO grade 4) harbor mutated isocitrate dehydrogenase 1 (IDH1R132H; mIDH1). Mutant IDH1 results in the accumulation of 2-hydroxyglutarate (2HG) which elicits profound changes in the glioma transcriptome/biology. Consequently, mIDH1 glioma patients have a significantly increased median survival compared to wildtype IDH1 patients. Recent data from our lab showed that mIDH1 gliomas exhibit increased immune-reactivity of tumor-infiltrating immune cells. A critical pathway that mediates reduction of anti-tumor immune cell reactivity is the adenosinergic pathway (AP), which converts ATP into adenosine via the enzymes CD39 and CD73. Adenosine binds to adenosine receptors, A2AR and A2BR, on immune cells resulting in a decreased immunoreactivity. Although mIDH1 has been implicated in altering the AP, the extent to which the AP is affected by mIDH1 in gliomas is largely unknown. Here we used human and mouse mIDH1 glioma cells in vitro along with in vivo mIDH1 glioma mouse models to examine changes in the AP. Our results show reduced levels of the enzyme, CD73, on the surface of mIDH1 glioma cells, and the ATP concentration in the mIDH1 glioma cell growth media is lower than from wildtype IDH1 glioma cells. Additionally, we discovered that mIDH1 glioma-infiltrating macrophages have decreased expression of CD39 and A2AR compared to their wildtype IDH1 glioma counterparts. Taken together, these data suggest a reduction of the AP mediated-immune suppression in mIDH1 gliomas. Uncovering these differences in the AP provides novel insights on the use of AP inhibitors for glioma treatment, revealing whether the AP is a preferred target in specific glioma types based on the IDH1 mutation status.
IMMU-20. MESSENGER RNA CHALLENGE RAPIDLY PREDICTS BRAIN TUMOR RESPONSIVENESS TO CHECKPOINT INHIBITORS
Authors: Castillo Paul , Ogando-Rivas Elizabeth , Geffrard Hillary , Pepe Alfonso , Liu Ruixuan , Nguyen Duy , Pedro Diego , Zhang Dingpeng , DeVries Anna , Qdaisat Sadeem , Grippin Adam , Karachi Aida , Rahman Maryam , Milner Rowan , Huang Jianping , Ligon John , Silver Natalie , Li Derek , Lee Ji-Hyun , Carrera-Justiz Sheila , Weidert Frances , Mitchell Duane , Mendez-Gomez Hector , Sawyer W Gregory , Sayour Elias
Published: November 2023

BACKGROUND

Pathogen recognition receptor (PRR) activation is requisite for igniting the immune response and making the tumor microenvironment ‘hot’ during oncogenesis. We theorized that these PRRs would remain present in ICI responsive tumors and could be challenged using pan-PRR mimic to prospectively predict brain cancer immunogenicity and response to immune checkpoint inhibitors (ICIs).

METHODS

By layering mRNA into multilamellar nanoparticles (ML RNA-NPs), multiple pathogen recognition receptors can be simultaneously activated in individualized cancer cells serving as a broad screen to test tumor immunogenicity. We challenged murine brain tumor lines known to respond (GL261 and SMA-560) or resist ICI treatment (KR158b and CT2A) with ML RNA-NPs and analyzed downstream production of proinflammatory cytokines as predictors of ICI response.

RESULTS

We demonstrated that ML-RNA-NPs can activate multiple PRRs simultaneously. Following ML RNA-NP challenge, ICI responsive tumors GL261 and SMA-560 (compared to more ICI resistant lines KR158b and CT2A) elicited increased production in pro-inflammatory cytokines such as IFN-β and IL-6 and in CCL4. To further develop this work into a commercially viable tool to predict ICI response, we developed 3D modeling of glial tumors for ML RNA-NP challenge and immunogenicity prediction. We enrolled canines with primary gliomas and began growing their tumoroids in 3D using liquid-like solid (LLS) technology. Using this pipeline, we successfully perfused 3D tumoroids with ML RNA-NP demonstrating ability to set up real-time patient derived explants to predict immunogenicity. We demonstrated that mRNA perfusion of 3D tumoroids elicited similar cytokine response observed with 2D culture of cell-lines.

CONCLUSION

Our results indicate that cytokine signatures following ML RNA-NP challenge differ significantly from ICI responsive versus non-responsive brain tumors. These findings allow for creation of a diagnostic assay to quickly assess brain tumor immunogenicity, allowing for informed treatment with ICIs.
IMMU-27. NON-TUMOR CELL IDO1 NON-ENZYMATICALLY DECREASES RT + PD-1 MAB TREATMENT EFFICACY IN OLDER ADULTS WITH GLIOBLASTOMA
Authors: Zhai Lijie , Bell April , Asimakidou Evridiki , Lauing Kristen , Kim Miri , Bommi Prashant , Barton Kevin , Borys Ewa , Anderson Douglas , Prabhu Vikram , Walunas Theresa , Schiltz Gary , Allen Jacob , McCusker Robert , Thakkar Jigisha , Lukas Rimas , Wainwright Derek
Published: November 2023

Checkmate 498 is a large, randomized, phase 3 clinical trial that demonstrated an improved hazard ratio for younger but not older adults with MGMT unmethylated GBM treated with RT + PD-1 mAb. In an effort to better understand the biological determinant, indoleamine 2,3 dioxygenase 1 (IDO1), and its relationship with reducing RT + PD-1 mAb treatment efficacy in older adults with GBM, we created and/or compared 20-26 month-old C57BL/6 background mice that were IDO1-T2A-GFP [wild-type (WT); negative control (n=16)], IDO1 enzyme null [with normal IDO1 expression potential but incapable of tryptophan metabolism (n=16)], IDO1KO (n=4), Ido1fl/fl (n=14), Lysm-Cre+→Ido1fl/fl [IDO1-deficient in monocytes, macrophages, and microglia (n=20)], CD11c-Cre+→Ido1fl/fl [IDO1-deficient in dendritic cells (n=23)], Tie2-Cre+→Ido1fl/fl [IDO1-deficient in endothelial cells (n=14)]. Mice were intracranially (ic.) engrafted with 5×103 syngeneic GL261 followed by treatment with radiation (RT) + PD-1 mAb beginning at 14-days post ic. IDO1 WT and IDO1 enzyme null mice had a survival rate of 12.5% and 18.75% at 90-day post ic., respectively, which was significantly reduced as compared to IDO1KO mice with a 75% survival rate (p< 0.05). Tie2-Cre+→Ido1fl/fl mice, CD11c-Cre+→Ido1fl/fl, and Lysm-Cre+→Ido1fl/fl mice had a 100%, 96%, and 70% survival rate at 90-day post ic., respectively, as compared to Ido1fl/fl mice with a 42% survival rate (p< 0.05). Significantly reduced kynurenine (KYN) levels were found in IDO1 enzyme null and IDO1KO mice as compared to WT mice (p< 0.001). Unexpectedly, kynurenine levels were also reduced in Tie2-Cre+→Ido1fl/fl but not in CD11c-Cre+→Ido1fl/fl, Lysm-Cre+→Ido1fl/fl or Ido1fl/fl mice (p< 0.05). Tryptophan (TRP) levels did not change between mouse groups. These data support the hypothesis that non-tumor cell IDO1 reduces immunotherapeutic efficacy in older adults with GBM through a TRP-KYN pathway-independent mechanism.
IMMU-31. B-CELL THERAPY (BVAX) PROMOTES CD8 T CELLS' PERSISTENCE AND FUNCTION IN THE GLIOBLASTOMA MICROENVIRONMENT BY MAINTAINING THEIR STEM-LIKE FEATURES
Authors: Wan Hanxiao , Hou David , Katz Joshua , Wang Si , Castro Brandyn , Chia Tzu-Yi , Cervantes Gustavo Ignacio Vazquez , Billingham Leah , Arrieta Victor , Han Yu , Lopez-Rosas Aurora , Zhang Peng , Miska Jason , Lee-Chang Catalina
Published: November 2023

The last decade witnessed tremendous improvement in immunotherapy to treat cancers. Its application in GBM has been particularly challenging due to the immunosuppressive tumor microenvironment, which greatly challenges T-cell infiltration and function. We developed a B-cell therapy with potent antigen-presenting functions that promote CD8+ tumor tropism and persistence in the tumor microenvironment. The present study investigates how BVax activates CD8+ T cells differently from other professional APCs like dendritic cells (DC) that could explain the persistence of CD8+ T cells in the tumor microenvironment. Upon in vitro activation by coculturing with BVax, most CD8+ T cells proliferated into TCF+ PD1- intermediate state, with CD44+ CD62L+ memory phenotype. Less than 10% of CD8+ were in the terminally-proliferation state. In contrast, DCs preferentially expanded TCF- PD1+ terminally-proliferating CD8+ T cells that were exhibiting CD44+ CD62L- effector phenotype. In vivo, activation of CD8+ T cells by co-injecting BVax or DC with CD8+ T cells to CT2A-bearing mice indicated that BVax promoted the proliferation of tumor-reactive CD8 T cells while maintaining the low PD1+ expression. Re-exposing the ex vivo-activated CD8+ T cells to tumor by adoptive transferring them to CT2A tumor-bearing mice revealed that BVax elicited immunological memory and potentiated GzmB+ production of CD8+ T cells. This study suggests that BVax and DC have distinctive interactions with CD8+ T cells, with the former poise CD8+ T cells at a more stem-like state, allowing them to differentiate upon tumor encounter.
IMMU-32. CAN PEMBROLIZUMAB TREAT RECURRENT GLIOBLASTOMA AND REVERSE HIV LATENCY?
Authors: Kaur Jaspreet , Silveira William , MacDonald Robert Loch , Mo Fan , Bao Silin , Yuen Carlen
Published: November 2023

Immunotherapy revolutionized treatment for many solid tumors. Early studies show that immunotherapy may be effective for recurrent glioblastoma. The ongoing Phase 2 LEEP-005 clinical trial (pembrolizumab+lenvima) is currently enrolling glioblastoma patients, but excludes patients with HIV. However, there is a strong need to treat this special patient population. One of the barriers to achieving cure in HIV patients is HIV latency within infect CD4+ T cells. Recently published data suggests that pembrolizumab can reverse HIV latency by forcing the HIV out of intracellular hiding into the plasma where anti-retroviral therapy can be effective. We present a case of a 39 year-old male with HIV and a Left Parietal Glioblastoma who had progressive disease following a subtotal resection and radiation alone due persistent neutropenia. Post-radiation MR brain wwo showed progressive disease in the left parietal lobe and new dural-based lesions in the left frontal and temporal lobes. HIV viral load was < 20 and CD4 count was 406 on HAART. The patient declined lenvima, but was amenable to bevacizumab. At 1 month follow-up, after 1 infusion of pembrolizumab 200mg and 2 infusions of bevacizumab, he achieved CR in the original site of disease and stable disease in the left frontal and temporal lobes. HIV viral load was 52. CD4 count was 660. Though it is too early to draw any firm conclusions, in our patient, pembrolizumab appears to induce HIV reversal, which is supported by an increase in the increase in his HIV viral load. The combination of pembrolizumab and bevacizumab appears to be effective at short-term follow-up. Our study is significant because there is limited evidence on the use of PD-L1 inhibitors in active HIV patients with cancer. To our knowledge, our case is the first reported case of the use of pembrolizumab in a patient with HIV and glioblastoma.
IMMU-37. TARGETING NON-CATALYTIC ACTIVATORS OF THE PROTEASOME DECREASES TUMOR GROWTH AND ENHANCES ANTIGEN PRESENTATION IN GLIOBLASTOMA
Authors: Heemskerk Kyle , Hao Xiaoguang , Cseh Orsolya , Luchman H Artee , Weiss Samuel
Published: November 2023

Glioblastoma (GBM) is the most common adult primary brain tumor plagued by inevitable recurrence and poor survival. We recently performed a genome wide CRISPR/Cas9 essentiality screen in GBM stem cells, revealing a plethora of potential targets for further exploration. The proteasome is a multimeric protein complex that degrades cellular proteins contributing to homeostatic proteostasis, stress response, and antigen presentation. Most proteasomal subunits are essential for GBM stem cell growth in vitro, however, they are also essential for non-malignant neural cells, suggesting that inhibition of those subunits may lead to toxicity. Indeed, adverse neurological symptoms were prevalent in phase III clinical trials for the brain penetrant proteasome inhibitor, Marizomib, which may be linked to the vital role of proteasome subunits in non-malignant neural counterparts. Proteasome inhibitors target the catalytic subunits of the proteasome, however the role of individual proteasome activators, most of which are non-essential for growth in vitro, have not been fully elucidated in GBM. Here, we examined the functionality of non-essential proteasome activator subunits in GBM stem cells in vitro and in vivo. Surprisingly, despite lack of growth changes in vitro, we observed abrogated stem-cell self-renewal in vitro and improved survival in vivo in orthotopic xenograft models following targeting of specific activator subunits. Molecular profiling of targeted cells revealed an upregulation of interferon-γ signaling and upregulation of antigen presentation machinery. Thus, targeting specific activator subunits may inhibit malignant growth in vivo while sparing normal neural counterparts from proteotoxic stress. We are further investigating enhanced antigen presentation by targeting these proteasome activator subunits and examining changes in the tumor microenvironment and survival in syngeneic immunocompetent models of GBM. Further understanding of this mechanism may provide novel targets for GBM treatment or improve immunotherapies in GBM.
IMMU-46. MONITORING T-CELL DYNAMICS AND CHECKPOINT EXPRESSION IN THE IMMUNE MICROENVIRONMENT OF PEDIATRIC HIGH GRADE BRAIN TUMORS: THE MIMIC PROGRAM
Authors: Meesters-Ensing Joyce , Carvalheiro Tiago , Kranendonk Mariëtte , Van Baarsen Kirsten , Hoving Eelco , Calkoen Friso , van der Lugt Jasper , Nierkens Stefan
Published: November 2023

BACKGROUND

Pediatric high grade brain tumors (pHGBT) pose a significant challenge due to limited treatment options and poor prognosis. Understanding the immune landscape, in particular T cell profiles and functionality, is of high interest as numerous immunotherapeutic approaches focus on or utilize T-cells. This study aimed to characterize T-cell phenotypes and their potential for immunotherapeutic interventions in tumor fragments (obtained from cavitron ultrasonic surgical aspiration (CUSA)) and tumor tissue (biopsy), in comparison with peripheral blood, collected from pHGBT patients.

METHODS

Spectral flow cytometry was employed to characterize the presence of T-cell subsets and their functional phenotype.

RESULTS

T cells were detected in all materials with similar CD8/CD4 ratios. At diagnosis, T-cells in the tumor microenvironment exhibited significantly increased expression of PD1, LAG3 and TIM3 checkpoint receptors compared to peripheral blood. This difference was more pronounced in biopsy samples compared to CUSA fragments. T-cell composition and phenotype in peripheral blood were similar to healthy adult controls at diagnosis. However, during therapy, the T-cell compartment showed a shift towards a higher CD8/CD4 ratio, accompanied by increased activation markers (CD25, CD69) and checkpoint receptor expression . Notably, CD8+ T-cells in both peripheral blood and tumor microenvironment showed high production of Granzyme B.

CONCLUSION

Our findings demonstrate that despite the high expression of checkpoint receptors on CD8+ T-cells, these cells retain the capability to produce significant amounts of Granzyme B, indicating their potential for cytotoxic activity. Furthermore, variations in checkpoint receptor expression on T-cells were observed when comparing CUSA fragments to biopsy material. Functional assays will further validate these findings and elucidate the functional status of these cells. Understanding the function of T-cells within the tumor microenvironment is essential for designing novel combination therapies to enhance T-cell cytotoxicity against pHGBT.
IMMU-48. SOLUBLE CIRCULATING IMMUNE CHECKPOINT MOLECULES IN MALIGNANT BRAIN TUMORS
Authors: Ryba Alice , Maire Cecile , Drexler Richard , Kolbe Katharina , Heinemann Sarina , Pantel Klaus , Gempt Jens , Westphal Manfred , Ricklefs Franz L , Wikman-Kocher Harriet , Riethdorf Sabine , Lamszus Katrin , Mohme Malte
Published: November 2023

Immune checkpoint therapy has been shown to be effective in several types of cancer, and tumor-directed immune activation is also a promising strategy in glioblastoma (GBM) patients. Our goal was to discover alterations in the circulating immunome of GBM patients and other cerebral tumor entities to identify soluble immune biomarkers and novel therapeutic targets. We analyzed 30 markers in plasma of 208 patients and healthy donors, using bead-based multiplex assays and flow cytometry. In a smaller cohort we further applied a high-sensitivity discovery biomarker platform with 368 markers. We included patients with 1) primary GBM (n=68), 2) recurrent GBM (n=25), 3) cerebral metastases (NSCLC, n=61; breast cancer, n=19), 4) meningioma (n=15) as well as 5) healthy donors (HD, n=20). We detected a distinct immune signature in the peripheral blood of patients with GBM, which was defined by an increased prevalence of soluble immune checkpoint markers (sCD27, sPD-L2, sGal-9), whereas soluble chemokines (CX3CL, CXCL12) were underrepresented. This signature was similar in primary and recurrent GBM, but differed markedly from other cerebral tumor entities as well as from HD. Primary GBM, but not their recurrent counterparts, additionally exhibited increased levels of neurotrophic factors (BDNF, b-NGF) and signs of immune activation with significantly increased levels of IL-18. The biomarker discovery platform further identified 76 proteins that were specifically regulated in GBM compared to HD, offering the potential to serve as biomarkers for disease activity. GBM patients with higher levels of BDNF displayed a significantly shorter survival than patients with lower levels (9.33 vs. 21.90 months; p=0.0001). Likewise patients with high concentrations of VEGF survived significantly shorter than those with low concentrations (12.97 vs. 21.90 months, p=0,0166). Taken together, we were able to delineate a specific immune profile of soluble markers in GBM patients compared to other cerebral tumor entities and to healthy individuals.
IMMU-50. DIFFERENCES IN GUT MICROBIAL COMPOSITION BETWEEN PEDIATRIC BRAIN TUMOR PATIENTS AND HEALTHY CONTROLS – THE MIMIC PROGRAM
Authors: Hoogendijk Raoull , van den Broek Thijs , Carvalheiro Tiago , Lammers Julie , Legemaat Monique , Quaedvlieg Miguel , van Mastrigt Esther , de Zoete Marcel , Top Janetta , Mueller Sabine , Kline Cassie , Calkoen Friso , van der Lugt Jasper
Published: November 2023

INTRODUCTION

The gut microbiome has been hypothesized to influence tumor initiation, immune evasion and treatment response in CNS tumor patients via the gut-brain axis, but data remains limited. To begin to address this question, we compared the gut microbial composition in a cohort of pediatric high-grade brain tumor patients with healthy controls.

METHODS

Within the MIMIC program, we prospectively collected fecal samples from 33 pediatric brain tumor patients at diagnosis and 26 pediatric healthy controls (HC) (< 21 years of age). Samples were analyzed using 16S rRNA amplicon sequencing of the V3-V4 region. Group differences were tested through the α- and β-diversity. Additionally, differential abundance (DA) analyses were performed.

RESULTS

Brain tumor patients (16 embryonal and 17 glial) significantly differed in age from HC (median 8 years vs 5 years, p< 0.001). Patient vs HC comparison revealed a comparable α-diversity (Shannon-index p=0.45), but significantly different β-diversity (Permanova test p=0.02). Corrected for age, DA revealed 18 genera with a significant log fold change. Twenty five of 33 brain tumor patients received dexamethasone during or prior to fecal sampling and 32 out of 33 patients received cefazolin, a first generation narrow-spectrum cephalosporin targeting mainly gram-positive bacteria, during surgery and before sample collection. Steroid use within brain tumor patients did not statistically affect α-diversity, β-diversity or DA. However, the impact of intravenously administered cefazolin during surgery on the gut microbiome in brain tumor patients remains unknown.

CONCLUSION

We report significant differences in gut microbial composition between pediatric brain tumor patients at diagnosis and healthy controls. DA revealed clinically relevant differences in Agathobacter , Fusicatenibacter , Eggerthella , and Hungatella. However, differences may be impacted by cefazolin administration. If and how gut microbial composition at diagnosis is associated with treatment efficacy and toxicity is subject to further research within the MIMIC program.
IMMU-53. MONITOR THE IMMUNE MICROENVIRONMENT AND SYSTEMIC IMMUNE EFFECTS IN PEDIATRIC BRAIN TUMORS – THE MIMIC PROGRAM
Authors: Hoogendijk Raoull , Carvalheiro Tiago , Lammers Julie , Kranendonk Mariëtte , Meesters-Ensing Joyce , Stunnenberg Hendrik , Kool Marcel , Bunt Jens , Heutinck Anneke , Adams Lisette , Van Baarsen Kirsten , Nierkens Stefan , Calkoen Friso , van der Lugt Jasper
Published: November 2023

INTRODUCTION

Dismal outcomes of pediatric high-grade CNS tumors demand new therapeutic strategies. A better understanding of the immune system may contribute to designing better immunotherapies for these children. The MIMIC program (Dutch Trial Registry NL8967) is a prospective observational longitudinal cohort study, conducted in patients with newly diagnosed or relapsed high-grade CNS tumors with the aim of characterizing and quantifying changes in immune parameters at diagnosis and during treatment.

METHODS

All patients with a newly diagnosed or relapsed high-grade CNS tumor are included after obtaining informed consent. Patient study material is collected longitudinally and includes tumor tissue (TT), Cavitron Ultra Sonic Aspirator (CUSA) material and optional bone marrow aspiration (BM) at diagnosis and relapse. Cerebrospinal fluid (CSF), peripheral blood (PB) and fecal samples (FS) at diagnosis, 3 months, 6 months, 12 months, relapse and additionally collection of CSF and FS at 14 days. Furthermore, FS is collected from patient siblings as a reference.

RESULTS

The MIMIC program has opened in June 2021 in the Princess Máxima Center, the national pediatric oncology center in the Netherlands, including so far 47 patients (out of ~60 eligible patients annually). More than 400 samples, out of which 46 TT, 34 CUSA, 65 CSF, 14 BM, 143 PB, and 105 FS have been collected. All samples are subject to extensive immunological profiling using 70+ markers flow cytometry panels (PB, TT, CUSA, CSF, BM), (spatial single cell) RNA and protein profiling (TT, CUSA, BM), immunohistochemistry (TT), proteomics (CSF and PB), and 16S rRNA or shotgun metagenomic sequencing (FS).

CONCLUSION

The MIMIC program demonstrates the feasibility of obtaining various samples for pediatric high-grade CNS tumors. By incorporating multiple technologies in longitudinal samples, the MIMIC program provides insight into the different immune compartments and their relation to the tumor, forming the base for future clinical trials with immunotherapy.
IMMU-54. PNEUMOCYSTIS JIROVECII PNEUMONIA INFECTION IN A PATIENT WITH ANAPLASTIC ASTROCYTOMA AND RADIATION NECROSIS IN THE SETTING OF CORTICOSTEROID AND PEMBROLIZUMAB USE
Authors: Choi Yoon , Kong Xiao-Tang
Published: November 2023

We present a case with anaplastic astrocytoma and radiation-induced brain necrosis, diagnosed with pneumocystis jirovecii pneumonia(PJP) while receiving corticosteroid and pembrolizumab, an immune checkpoint inhibitor(ICI). ICIs have significantly changed management of many cancer types and are known to be associated with immune related adverse events(irAEs). Recently, concerns have emerged regarding the potential relationship between ICI use and infection risks, and PJP, a rare opportunistic infection, has been reported in patients with ICI treatments with or without corticosteroid use. A 40-year-old man with anaplastic astrocytoma and radiation-induced brain necrosis on corticosteroid and pembrolizumab presented with high fever and tachycardia over three days, and the patient later developed hypoxia and cough. The patient was on dexamethasone for brain radiation necrosis for two months and he received one dose of pembrolizumab two weeks prior to his symptom onset, based on genetic information that showed hypermutated tumor and abnormal DNA mismatch repair protein expression. Chest CT showed abnormal findings from infectious or inflammatory process. Bronchoalveolar lavage sample confirmed positive pneumocystis jiroveci PCR test, confirmed PJP, and he was treated with clindamycin, primaquine, and prednisone. To the best of our knowledge, this is the first reported case of PJP in a patient with primary brain tumor receiving corticosteroid and pembrolizumab. ICIs are being investigated in patients with primary brain tumors and wildly used in patients with malignancies with frequent central nervous system involvements, such as malignant melanomas and non-small cell lung cancers. Awareness of risk for infectious conditions including PJP in patients on ICI treatment, especially with corticosteroid use is crucial for implementing appropriate prophylactic measures and prompt diagnosis and treatment interventions.
IMMU-56. TARGETING NONO IN GLIOMA VIROIMMUNOTHERAPY
Authors: Gillard Andrew , Shin Dong Ho , Jiang Hong , Fan Xuejun , Singh Sanjay , Laspidea Virginia , He Jiasen , Lopez-Rivas Andres , Parthasarathy Akhila , Alonso Martha , Lang Frederick , Fueyo-Margareto Juan , Gomez-Manzano Candelaria
Published: November 2023

Despite aggressive therapies, the median survival for glioblastoma (GBM) patients remains just 7-months after tumor progression. Oncolytic virotherapy is a promising approach to reprogramming the immunosuppressed microenvironment of GBMs facilitating anti-tumor immunity. Delta-24-RGD is an oncolytic adenovirus that has shown favorable results in phase I/II clinical trials (NCT00805376, NCT03178032 and NCT02798406). However, the immune response of the patient functionally cleared the virus, limiting its anti-cancer efficacy to a subset (~20%) of patients. It is known that Non-POU Domain Containing Octamer Binding (NONO) is overexpressed in gliomas and is associated with poor survival of patients. Using bulk RNA sequencing, we showed that the NONO pathway is upregulated 7 folds during adenoviral infection. These results were confirmed by western blot analyses that showed a significant increase in the expression of NONO after Delta-24-RGD infection. We detected cellular and viral members of the NONO interactome using mass spectrometry analyses. Immunoprecipitation assays confirmed those results and showed that NONO binds to adenoviral proteins during infection and associates with the foreign DNA sensor cyclic GMP AMP synthase (cGAS). Using shRNA knockdown, we showed that NONO was required to induce innate immune activation in response to adenovirus infection. Thus, we observed a 180-fold increase in type I interferon after the infection with the virus that was reversed in NONO-null cells. Therefore, NONO is a previously undetected innate immune sensor of adenoviruses in the nucleus. In addition, the fact that NONO binds adenoviral proteins suggests a new double-sensor mechanism involving the detection of both foreign DNA and viral proteins. Interactions between NONO and adenoviral proteins should be considered when designing the next generation of oncolytic adenovirus for the treatment of gliomas.
INNV-16. COMPARISON OF SURVIVAL OUTCOMES OF RECURRENT GLIOBLASTOMA PATIENTS: A COMPARISON BETWEEN PATIENTS ENROLLED INTO CLINICAL TRIALS AND PATIENTS THAT DID NOT ENROLL INTO TRIALS AT FIRST PROGRESSION
Authors: Balasubramanian Geethanjali , Yerramothu Shruti , Youssef Gilbert , Lee Eudocia , Castro Luis Nicolas Gonzalez , McFaline-Figueroa Jose Ricardo , Nayak Lakshmi , Reardon David , Trippa Lorenzo , Wen Patrick , Rahman Rifaquat
Published: November 2023

BACKGROUND

Clinical trials in neuro-oncology use stringent eligibility criteria to select patients. We examined potential differences of survival outcomes in recurrent glioblastoma patients participating in clinical trials compared to trial-eligible patients treated outside of a trial.

METHODS

We reviewed 378 adult IDH-wild-type glioblastoma patients treated for first recurrence at our institution 2014-2020. We retrospectively evaluated patients for clinical trial eligibility based upon review of performance status, laboratory values (e.g. comprehensive metabolic panel, complete blood count), and other common eligibility criteria. Overall survival was defined as time from date of first recurrence to death. Cox proportional hazards modeling were used to evaluate outcomes of trial eligible patients compared to patients who received treatment on a clinical trial.

RESULTS

Among 378 patients, 171 patients (47%) enrolled onto a trial at first recurrence. Amongst 207 non-trial patients, 65 patients were excluded due to ineligibility or missing data. The primary reasons for trial ineligibility was known additional malignancy, thrombocytopenia, KPS < 60, active autoimmune disease, and presence of diffuse leptomeningeal disease. There were 142 (69%) patients deemed trial-eligible per our retrospective screening. In trial-eligible non-trial and trial participants (N=313), trial participation was associated with improved survival (Adjusted-HR 0.58, 95%CI 0.43-0.77, p< 0.001) after adjustment for age (HR 1.02, 95%CI:1.01-1.03, p=0.01), MGMT promoter methylation (HR 0.64, 95%CI:0.47-0.88, p=0.008), KPS at first recurrence (HR 0.99, 95%CI:0.97-1.00, p=0.02), time to first recurrence (HR 1.00, 95%CI:0.999-1.00, p=0.07), surgery at first recurrence (HR 0.96, 95%CI:0.72-1.27, p=0.77), standard 6 weeks radiation upfront (HR 0.47, 95%CI:0.25-0.87, p=0.02), and concurrent temozolomide use upfront (HR 0.71, 95%CI:0.43-1.15, p=0.18).

CONCLUSION

The most common reasons for clinical trial ineligibility in our cohort was additional malignancy, thrombocytopenia and poor performance status. In a single institution recurrent glioblastoma cohort, trial participation was associated with improved survival after adjustment of clinical covariates in this cohort.
INNV-24. MACHINE LEARNING-BASED SPECTROSCOPIC TISSUE DIFFERENTIATION IN FLUORESCENCE-GUIDED NEUROSURGERY
Authors: Black David , Byrne Declan , Walke Anna , Liu Sidong , Ieva Antonio Di , Stummer Walter , Salcudean Tim , Molina Eric Suero
Published: November 2023

Maximal resection of malignant gliomas is hindered by difficulty in distinguishing tumor margins. Fluorescence-guided resection with 5-ALA assists in reaching this goal. Previously, we characterized five fluorophore emissions that accurately represent any spectrum measured from human brain tumor biopsies with a wide-field hyperspectral device. In this study, the effectiveness of these five spectra was explored for different tumor classification tasks in 891 hyperspectral widefield measurements of 184 patients harboring low- (n=30) and high-grade gliomas (n=115), non-glial primary brain tumors (n=19), radiation necrosis (n=2), miscellaneous (n=10) and metastases (n=8), which corresponds to up to 15000 spectra for a given test. The statistical differences in fluorophore abundances between classes were determined and visualized using dimensionality reduction techniques, including principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE). Three machine-learning models were trained to classify tumor type (12 classes), grade (3 classes), and glioma margins (3 classes). Five algorithms were tested with varying hyperparameters for each classification task. We explored whether PCA projection onto five different axes than fluorophore abundances can provide more information for visualization and classification. The abundances of the five a priori fluorophore spectra matched or outperformed the five optimal PCA components for all classification tasks. These five axes capture 96-99% of the variance in the dataset. Using random forests and multilayer perceptrons, the classifiers achieved average test accuracies of 74-82%, 79%, and 81%, respectively. All five fluorophore abundances varied between tumor margin type as well as between grades (p < 0.01). For tissue type, at least four of five fluorophore abundances were found to be significantly different (p < 0.01) between all classes. These results demonstrate the differing contribution of fluorophores in different tissue classes tissue, as well as the five fluorophores value as potential optical biomarkers, opening new opportunities for intraoperative classification systems in fluorescence-guided neurosurgery.
INNV-28. SCIENTIFIC LITERACY AND DECISION-MAKING OF PATIENT FAMILIES IN PEDIATRIC NEURO-ONCOLOGY
Authors: Lyons Nicole , Ward Lisa
Published: November 2023

Pediatric neuro-oncology, especially when treating typically terminal tumors such as DIPG, exists in a fluid, complicated state. There exists no standard, effective, and tolerable treatment. This means all patients are on clinical trials for treatment, placing the child’s care on the cutting edge of an already complicated field of research. A concern frequently brought up by parents is the struggle to understand scientific articles about their child's condition. Without a solid foundational understanding of molecular biology, the majority of their time reading research is spent googling terms only scientists are familiar with. A survey of 40 questions was developed and disseminated amongst families of children diagnosed with DIPG/DMG via email, with 64 participants The intent was to investigate what level of relevant scientific literacy the average parent had at diagnosis, during decisions on treatment, and where it is currently. RESULTS: showed at the time of diagnosis, 89.4% of families had never heard of Diffuse Intrinsic Pontine Glioma, let alone understood its mechanisms and treatment options. There is existing patient education, but current education does not go into the level of scientific detail needed. The result shows that 86.5% of families are spending at least 10 hours each week researching conditions outside of doctor appointments. At the time of diagnosis, 84.4% of families have little to no familiarity with clinical trials at all, yet 61.4% of those families are making decisions on participation under a month from diagnosis. The decisions families make impact patients’ quality of life, the development of effective and safe treatments, and if their child passes, their grieving. A better understanding of disease and treatment has been consistently shown to result in better outcomes by a variety of measures. Patient education focused on scientific literacy is desperately needed to match families' decision-making needs.
INNV-31. ADOPTING TUMOR TREATING FIELDS (TTFIELDS) THERAPY FOR GLIOBLASTOMA AND OTHER SOLID CANCERS: CHALLENGES AND OPPORTUNITIES
Authors: Lustgarten Leonardo , Tatsui Claudio , Williams Matthew , Sengupta Soma , Wong Eric
Published: November 2023

Tumor Treating Fields (TTFields) are alternating electric fields generated by a wearable medical device (NovoTTF-200A), delivered to the tumor target by arrays placed on the skin. These fields have multiple biological effects on tumor cells, including mitotic disruption, dysregulated DNA repair, antimigratory effects, and stimulation of antitumor immune response. TTFields therapy was approved for recurrent and newly diagnosed glioblastoma, based on the randomized, pivotal EF-11 and EF-14 studies, respectively. Data from both studies demonstrated favorable outcomes, sustained quality of life, and tolerable safety profile. Side effects are limited to mostly manageable, mild to moderate skin reactions with no increased systemic toxicity. TTFields therapy is also approved for pleural mesothelioma and has met the primary endpoint in the pivotal LUNAR study for metastatic non-small cell lung cancer patients. Despite extensive preclinical data, positive clinical study outcomes, and favorable real-world evidence, adoption of TTFields therapy remains tepid. Here we discuss potential causes and possible solutions to treatment barriers. Based on extensive surveys in the field, we have identified several potential reasons. The first challenge is the perception that open-label studies are less rigorous since sham devices are not used per protocol. The purpose of sham treatments in trials is to minimize placebo effects and/or investigator bias, but RANO criteria is designed to guard against just that. Secondly, dissemination of knowledge underlying innovative therapies often takes time. Unlike chemotherapy and radiotherapy, the mechanistic aspects of TTFields are not typically included in oncology training. Lastly, the benefits of TTFields therapy may be difficult to appreciate due to the required chronic use during maintenance. Therefore, education, additional bench research, and future clinical studies are important for a better adoption of this increasingly important oncological option.
INNV-33. NEURO-ONCOLOGY VISITS AT HOME (NOVAH): A PILOT PROGRAM TO IMPROVE CARE FOR PATIENTS WITH BRAIN CANCER
Authors: Eichler April , Merker Vanessa , Von Imhof Liesel , Pavlovich Renee , Forst Deborah , Plotkin Scott R
Published: November 2023

Informational and care needs of brain cancer patients change rapidly and often outstrip the capacity of clinical encounters at key time points, including transitions from inpatient to home and times of high emotional and psychological needs (e.g., new diagnosis, disease progression). The existing care-model leaves little time for illness understanding and advance care planning (ACP) work. We piloted a home visit program (NoVaH) to assess feasibility and acceptability of specialty-level clinical support in the home at times of increased care needs. METHODS: Eligible patients were treated in the neuro-oncology practice of a single academic medical center, resided within 15 miles of the hospital, and were referred by clinic staff. Home visits were conducted by a neuro-oncologist one half-day per week and scheduled longitudinally according to need, in parallel with primary outpatient visits. 9 family caregiver interviews were conducted virtually and analyzed by a qualitative researcher using rapid analysis methods to synthesize findings across predetermined, deductive categories. RESULTS: 18 patients referred from outpatient (61%) or inpatient service (39%) completed ≥ 1 home visit. Most patients had glioblastoma (78%). 59 home visits took place over 12 months (median per patient 2, range 1-8). A first life-sustaining treatment order form was completed by 10/18 patients (56%). Among 10 patients who died, place of death was home (50%), skilled nursing facility (20%), inpatient hospice (20%), or hospital (10%); 90% were enrolled in hospice at time of death. Caregivers voiced specific benefits such as ability to receive care patients would have otherwise forgone, improved communication about illness understanding and ACP, and enhanced sense of control and ability to digest prognostic information compared with office setting. CONCLUSIONS: Neuro-oncology home visits are feasible and acceptable to patients with brain cancer and represent an innovative way to provide patient-centered cancer care at times of transition and complex decision-making.