bluuebunny/crossref_metadata_2025 huggingface dataset:
CNSC-22. CANCER NEUROSCIENCE IN THE OR: ELECTROPHYSIOLOGIC INSIGHTS AT THE TIME OF BRAIN TUMOR RESECTION
Authors: Nelson Thomas , Coughlin Brian , Cahill Daniel , Dunn Gavin , Nahed Brian V , Cosgrove G Rees , Yang Jimmy , Farnsworth Hannah , Richardson R Mark , Cash Sydney , Venkatesh Humsa , Paulk Angelique
Published: November 2023

Pioneering works by Venkatesh and Venkataramani demonstrated that formation of functional neural-glial synapses fosters development and growth of glial neoplasms. Resultant peritumoral neural hyperexcitability associates with tumor progression, though limited in vivo human data have been evaluated to date. We sought to enrich our understanding of these mechanisms by obtaining thin film intraoperative micro-electrocorticography (µECoG) recordings from patients undergoing primary brain tumor resection. METHODS: Intraoperative µECoG data for 8 patients with low- (LGG) and high-grade glioma (HGG, WHO grades 3 and 4) of various tumor histology were included. Analyses excluded any operative behavioral or cognitive tasks and evaluated data prior to stimulation for language or motor mapping. Following low pass (< 200 Hz) and notch filtering at 60, 120, and 180 Hz for ambient electrical noise, bandpower was calculated using multitaper spectral analysis for low frequency (LF, < 1 Hz), delta (1-4 Hz), beta (12-30 Hz), gamma (30-80 Hz), and high gamma (80-200 Hz) bands. RESULTS: Compared to isocitrate dehydrogenase (IDH) wild-type tumors, those with IDH-mutation (n = 3; two WHO grade 3, one grade 4) demonstrated the highest proportion of power within the LF band (92.2% vs 71.4%) with relatively lower proportional beta (3.6% vs 18.3%) and gamma (2.2% vs 8.7%) bandpower. The same pattern was seen in HGG (n = 5) vs LGG (n = 3) tumors with higher LF (84.5% vs 70.3%) and lower beta (10.3% vs 16.8%) and gamma (3.5% vs 10.8%) bandpower, perhaps driven by three HGGs with IDH mutation. Absolute bandpower was highest at all bands in a patient with left frontal glioblastoma. CONCLUSIONS: Interesting patterns are emerging that corroborate differential high and low frequency neural activity among patients with primary brain tumors. Disparities in LF and beta/gamma bands may represent therapeutic targets or a non-invasive biomarker of disease activity but require further, ongoing data collection and analyses.
CNSC-25. NEURAL SIGNATURE OF GBM EXHIBITS SYNAPTOGENIC AND OPC-LIKE FEATURES AND INDEPENDENTLY PREDICTS PATIENT SURVIVAL
Authors: Drexler Richard , Khatri Robin , Sauvigny Thomas , Mohme Malte , Ryba Alice , Dührsen Lasse , Maire Cecile , Salviano-Silva Amanda , Lamszus Katrin , Westphal Manfred , Gempt Jens , Wefers Annika , Neumann Julia , Bode Helena , Hausmann Fabian , Huber Tobias , Bonn Stefan , Delev Daniel , Weber Katharina , Harter Patrick , Onken Julia , Vajkoczy Peter , Capper David , Wiestler Benedikt , Monje Michelle , Silverbush Dana , Hovestadt Volker , Suva Mario , Krishna Saritha , Hervey-Jumper Shawn , Schüller Ulrich , Heiland Dieter Henrik , Hänzelmann Sonja , Ricklefs Franz L
Published: November 2023

Interactions of neural cells with glioma cells drive tumor growth. In this study, we identified an epigenetically-defined, malignant neural signature of IDH-wildtype glioblastoma (GBM) that significantly influenced patients’ outcome. We used DNA methylation-based reference signatures of neural cells to deconvolve 1.058 primary patient GBM samples. Samples were classified based on the neural reference signature and annotated as low or high neural GBM. A high neural GBM was linked to hypomethylation of CpG sites associated with invasiveness, neuron-to-glioma-interactions, and transsynaptic signaling. Through spatially resolved, single cell transcriptomic and proteomic profiling, we discovered a correlation between the high neural signature and the upregulation of early development programs in OPC and NPC-like cells. These traits were accompanied by diminished immune infiltration and immunological response, further highlighting the distinctive neural-like nature of GBM. High neural GBM demonstrated increased connectivity as evidenced by magnetoencephalography and resting state magnet resonance imaging. Spatiotemporal tumor sampling showed a homogeneous and stable neural signature in newly diagnosed and recurrent GBM. In newly diagnosed GBM, a high neural signature correlated with decreased survival in 306 patients (median OS 15.0 versus 20.0 months, p< 0.001). Patient-derived xenograft models corroborated the aggressive nature of high neural GBM, showing a significantly reduced median OS of 58 days compared to 73 days (p< 0.01). These high neural GBM xenografts also exhibited an elevated tumor burden and an increase in neuron-glioma synapse formation. Consideration of the extent of resection showed a dependency on the neural subgroup as high neural GBM had an increased benefit from a complete contrast enhancing tumor removal when compared to low neural GBM. As a preoperative biomarker, the concentration of BDNF was increased in serum of high neural GBM patients (p < 0.01). Overall, we present an epigenetically-defined malignant neural signature in GBM that is associated with an unfavorable patient survival.
CNSC-38. CHARACTERIZATION OF THE FUNCTIONAL RELEVANCE OF INTRA- AND INTERTUMORAL NETWORKS IN PRIMARY BREAST CANCER
Authors: Nürnberg Christina , Schrenk-Siemens Katrin , Würth Roberto , Trumpp Andreas , Mayer Chanté , Karreman Matthia , Pan Chenchen , Wick Wolfgang , Winkler Frank
Published: November 2023

Despite intensive efforts to improve current therapeutical strategies, breast cancer continues to be a life-shortening diagnosis for a significant number of affected women. Considering that the innervation density of breast cancers negatively correlates with the prognosis, the emerging field of Cancer Neuroscience, which deals with the reciprocal interactions between the nervous system and cancer cells, represents an attractive novel research direction. In fact, studies on breast cancer brain metastases have proven that the metastatic cells receive growth stimuli by hijacking healthy glutamatergic synapses. Beyond being capable of forming direct glutamatergic cancer-neuron synapses, primary brain tumor cells also connect to a multicellular intercommunicating network that contributes to therapy resistance. Whether similar mechanisms also apply to tumors outside the brain – accountable for the majority of cancer cases – remains unknown. Here, we aim at unraveling the functional role of intratumoral networks and the influence of (potential) direct primary breast cancer cell-neuron interactions. We hypothesize that purinergic signaling as a universal synaptic signaling mechanism enhances tumor growth. Through the application of ex vivo whole-organ tissue-clearing and nerve-labeling approaches, we noticed prevalent sensory and sympathetic innervation in the healthy and diseased murine mammary gland. Furthermore, we measured tumor cell proliferation rates in an in vitro model of primary murine sensory DRG-neurons co-cultured with breast cancer stem cells and compared these to monoculture controls. By implanting a mammary imaging window over the growing primary tumor, we longitudinally track the calcium activity of breast cancer cells in their natural microenvironment in the living mouse. We thereby are able to record co-activity of neighboring cells indicative of intratumoral network communication in primary breast cancers. Overall, our data support the existence of functional intra- and intertumoral breast cancer cell networks as an alternative therapeutical target. Future work needs to concentrate on unequivocally detecting direct neuron-cancer cell contacts.
CNSC-39. GENERATION AND CHARACTERIZATION OF LIVING ORGANOTYPIC BRAIN SLICE CULTURES AS A NOVEL PRE-CLINICAL MODEL FOR BRAIN CANCER
Authors: Dasari Rajaneekar , Mann Breanna , Zhang Xiaopei , Bell Noah , Adefolaju Adebimpe , Thang Morrent , Kanchi Krishna , Valdivia Alain , Yang Yang , Buckley Andrew , Lettry Vivien , Quinsey Carolyn , Rauf Yasmeen , Kram David , Cassidy Noah , Vaziri Cyrus , Corcoran David L , Rego Stephen , Jiang Yuchao , Graves Lee M , Dunn Denise , Floyd Scott , Baldwin Albert , Hingtgen Shawn , Satterlee Andrew B
Published: November 2023

A challenge in cancer research is developing reproducible, reliable, and practical models which can capture the complexity of cancer development and treatment. The development of functional precision medicine platforms is emerging as a promising strategy for improving pre-clinical drug testing and guiding clinical decisions. We have developed an organotypic brain slice culture (OBSC) technology composed of intact multicellular tissue which can be rapidly used for spatiotemporal drug response testing. OBSCs are reproducibly generated from Sprague-Dawley rat pups and used as living tissue substrates to culture treat different tumor cell lines and uncultured patient brain tumor resection tissue. We evaluated OBSC quality and reproducibility throughout the study by using a propidium iodide nuclear permeability assay. This technique enabled a broad dynamic range to distinguish between healthy and unhealthy slices. In these studies, the rat pup age at the time of generation had an impact on OBSC quality and quantity, indicating that OBSCs should be generated from eight-day-old pups. We also found that optimal OBSCs were generated using improved methods for brain dissection and OBSC culture conditions, establishing our robust, standardized procedure for OBSC generation. Following this optimization period, we continued to conduct quality control analysis with 6 OBSCs per batch for reproducibility. We also conducted immunohistochemistry analysis immediately after slicing and concluded that morphology of neurons in OBSCs remained unchanged between day 0 and 4. In addition, the activation of astrocytes attenuates by day 4 but persists in macrophages/microglia, suggesting that the myeloid cells can phagocytose dead cells and debris in OBSCs. In summary, these results indicate that the OBSC platform may be an effective model that accelerates preclinical drug testing and directs drug development towards clinical evaluation.
CNSC-43. TARGETING NEURONAL EXCITABILITY FOR NF1 LOW-GRADE GLIOMA THERAPY
Authors: Anastasaki Corina , Chatterjee Jit , Gao Yunqing , Koleske Joshua P , Bozeman Stephanie L , Chen Ji-Kang , Kernan Chloe M , Gutmann David
Published: November 2023

While neuronal activity has previously been implicated in malignant glioma growth control, we recently demonstrated that neuron excitability can also regulate low-grade (optic) glioma initiation and progression. In this prior study, we showed that NF1 germline mutation-dependent neuronal excitability sustains optic glioma growth through HCN channel-mediated midkine activation of a T cell-microglia stromal circuit. Relevant to clinical translation, lamotrigine modulation of HCN channel function reduced neuronal hyperexcitability, midkine production and optic glioma (OPG) growth. To establish an obligate role for neuronal activity and midkine (Mdk) production in OPG growth, we leveraged a series of unique genetically engineered mouse models. First, we demonstrate that midkine is necessary for gliomagenesis, as Nf1-OPG; Mdk-/- mice do not develop tumors and have restored retinal pathology, as evidenced by increased retinal ganglion cell (RGC) numbers and retinal nerve fiber layer thickness. Second, we show that midkine production and neuronal hyperactivity are interdependent, such that only tumor-associated germline Nf1 mutations result in increased RGC excitability and midkine production, whereas those mutations that do not cause optic gliomas lack RGC hyperexcitability or elevated midkine expression. Third, lamotrigine treatment both during and after Nf1-OPG development attenuates midkine levels and tumor proliferation. Moreover, this anti-tumoral effect is durable for months after the cessation of treatment. Fourth, oral treatment of Nf1-OPG-bearing mice with clinically relevant doses of lamotrigine (2.5-7.5mg/kg/day) during OPG development blocks tumor formation. Together, these data establish midkine and neuronal hyperexcitability as key drivers of Nf1 optic glioma growth, relevant to planned clinical trials of this anti-seizure medication for children with NF1-OPG.
STEM-01. PLEXIN-B2 DRIVES CONFINED MIGRATION OF GLIOBLASTOMA STEM CELLS THROUGH MEMBRANE TENSION, ENDOCYTOSIS, AND MECHANO-ELECTRO REGULATION
Authors: Alves Chrystian Junqueira , Dixon Angela , Hannah Theodore , Wiener Robert , Nguyen Ha , Tipping Murray , Ladeira Júlia Silva , Dias Rodrigo Alves , Capriles Priscila Zabala , de Mendonça José Paulo Rodrigues Furtado , Slesinger Paul , Costa Kevin , Zou Hongyan , Friedel Roland
Published: November 2023

Glioblastoma is a malignant brain tumor of uncontrolled proliferation and infiltration. GBM stem cells (GSCs) are constantly challenged by confined spaces during their migration through the brain parenchyma. Understanding the factors that drive GSC confined migration (CM) is thus critical for effective drug development. Using microchannel devices, we showed that GSCs are adept at squeezing through narrow constrictions at faster speed than through non-constricted spaces. During CM, cytoskeletal components and plasma membrane self-organize to establish polarity and propel the cell through the constrictions. Among the mechanical plasticity observed for meeting the challenges of CM the cells remodel their shape and plasma membrane through increased endocytosis. Rapid endocytosis of inner leaflet anionic phospholipids-such as PI(4,5)P2 and phosphatidylserine at the front of the cell collectively contribute to drive positive-charged actin filaments and calcium to the rear end of cells, abruptly leading to localized changes in membrane potential and propelling the cell. Correspondingly, inhibiting endocytosis abrogates polarity and results in failure to CM. These effects were recapitulated by deletion of the cell surface receptor Plexin-B2. Plexin-B2-CRISPR knockout (KO) GSCs displayed reduced capability to squeeze through constrictions in microchannel devices. Mechanistically, Plexin-B2 KO in GSCs compromised membrane dynamics and reduced endocytosis as consequence of low cell stiffness and membrane tension. Computational simulations demonstrated that membrane tension couples with cell stiffness in feedback loops and support the model that Plexin-B2 controls membrane tension through actomyosin contractility. On a molecular level, the locked extracellular ring domain of Plexin-B2 prevents GSCs to migrate through constrictions and recapitulates the defects associated with Plexin-B2 KO phenotype, indicating that ring bending is required for membrane tension. Thus, our results describe critical mechano-electro events necessary to establish polarity and prompt GSCs migration under confinement and provide a mechanism by which a single mechanosensor exert regulation at the cytoskeletal and membrane levels.
STEM-16. PROMOTING THE CANCER STEM CELL SUBPOPULATION AND PHENOTYPE IN GLIOBLASTOMA VIA EXTRACELLULAR VESICLE CROSS-TALK
Authors: Inocencio Julio , Asad Mohammad , Aguilan Jennifer , Behnan Jinan , Sidoli Simone , Himes Benjamin
Published: November 2023

INTRODUCTION

Extracellular vesicles (EVs) released from cancer cells contain bioactive molecules that have been long implicated in tumorigenesis. In glioblastoma (GBM), there is mounting evidence that EVs play a role in critical processes including angiogenesis, immune suppression, and invasion. GBM secreted EVs have also been demonstrated to promote a cancer stem cell (CSC) phenotype by transporting stemness markers and proteins (I.e. Notch-1) involved in stem-cell activating pathways. Understanding the maintenance of CSCs, which contributes to tumor proliferation, treatment resistance, and re-expansion of the tumor bulk, can offer insight into new therapeutic drug targets that can disrupt this subpopulation.

METHODS

EVs were isolated from patient-derived primary GBM cell lines maintained as adherent cultures and free floating spheres (n = 3) using a staged ultracentrifugation technique. Normal astrocytes were used as the control group (n = 1). Protein expression profiles were then generated via high-throughput mass spectrometry for both EVs and whole cell lysate samples from the same cell line and compared against each other.

RESULTS

EGF-containing fibulin extracellular matrix protein 1 (EFEMP1) was shown to be upregulated in GBM derived EVs compared to control. Further analysis shows that EFEMP1 is enhanced in adherent cultures compared to free floating sphere cultures.

CONCLUSION

EFEMP1 is an extracellular matrix protein that has been identified as an oncogenic protein in GBM by activating Notch-1, Akt, and NF-Kb signaling pathways resulting in increased Temozolomide resistance, cellular proliferation, and invasion, all of which are hallmark characteristics of CSCs. EFEMP1 is also a downstream effector in the HIF-1 pathway, which has been strongly correlated in the maintenance of CSCs. Our results therefore demonstrate a possible EV mediated mechanism for the maintenance of the CSC population and phenotype in GBM.
STEM-21. DETERMINATION OF RACIAL DISPARITIES IN GLIOMA THROUGH RAP1B/NOTCH -INDUCED TUMORIGENESIS AND STEMNESS
Authors: Guo Shanchun , Guo Alyssa , Li Jason , Rama Vanajothi , Akpobiyeri Hannah , Hudson Breanna , Liu Mingli
Published: November 2023

BACKGROUND

The incidence of GBM and survival rates after diagnosis vary significantly by race, with Caucasian Americans (CAs) having higher incidence and lower survival rates than African Americans (AAs). Accumulating evidence suggests that the failure of current therapies is partly attributed to the presence of glioma stem cells (GSC), leading to tumor progression and recurrence. Our recent work demonstrates that Ras-associated protein 1 (Rap1), a Ras-like small GTP-binding protein superfamily member, has roles in glioma cell proliferation and invasion.

METHODS

1) The TCGA database was analyzed to investigate the predictive role of Rap1b in glioma patients. 2) The immunohistochemical staining for Rap1b1 was performed using the rabbit polyclonal anti-Rap1b in glioma tissue microarrays (TMA) from 76 glioma patients with 10 normal individuals. The staining intensity of cells in TMA was evaluated in three different bright fields (≥100 cells/field). The semi-quantitative HSCORE was calculated for Rap1b. 3) The mechanism of the oncogenic role of Rap1b in glioma was examined using in vitro cell culture.

RESULTS

1. TCGA data showed that Rap1b mRNA is highly expressed in GBM patients compared to normal controls, indicating that Rap1b is a potential oncotarget in GBM. Expression of Rap1b is associated with worse survival in glioma patients, especially in CAs, but not in AAs. 2. The TMA data showed that elevated Rap1b protein expression correlates with grades in glioma patients. 3. In vitro studies showed that GSCs exhibit high levels of Rap1b, silencing Rap1b decreases glioma cell growth and invasion through G1/S arrest and the induction of apoptosis, as well as reduces Notch1 signaling in glioma cells; while potentiates GBM cell response to TMZ.

CONCLUSION

This study provided new knowledge of Rap1b’s potential as a therapeutic drug target for GBM therapy and revealed biological diversity across races and unaddressed health disparities.
STEM-22. SINGLE-CELL LINEAGE TRACING IN PRIMARY GLIOBLASTOMA REVEALS DISTINCT PROGENITOR SUBTYPES DRIVING INTRATUMORAL HETEROGENEITY
Authors: Fazzari Elisa , Azizad Daria , Ge Weihong , Li Matthew , Tum Andrew , Tse Christopher , Patel Kunal , Muthukrishnan Sree Deepthi , Kornblum Harley , Nathanson David , Bhaduri Aparna
Published: November 2023

Glioblastoma (GBM) is the most common type of adult primary brain tumor with nearly a 100% rate of recurrence. One of the key clinical challenges is the vast degree of inter- and intra-tumoral variation in cell types and cell states, which change throughout the course of disease. Single-cell RNA-sequencing (scRNA-seq) studies in GBM samples have illuminated the complex landscape of cell type composition in primary and recurrent GBM, however these studies do not address how this diverse array of cell types developed or which cell populations are principally responsible for generating the heterogeneity and treatment resistance in the tumor. In this study, we implement a scRNA-seq compatible lineage tracing strategy, CellTagging, to track the behavior of individual tumor cells over time. Human GBM samples are dissociated immediately upon resection and infected with the CellTag DNA barcode library. The labeled cells are transplanted onto human cortical organoids, which facilitate the crucial normal-tumor cell interactions that enable GBM growth and invasion. After a period of proliferation, tumor cells are dissociated from the organoid and a fraction are harvested for scRNA-seq for transcriptomic and DNA barcode analysis. The remaining tumor cells are re-transplanted onto new organoids and harvested for scRNA-seq at later timepoints. Clonal relationships are determined by identifying cells with the same DNA barcode profile, and cell type characterizations are assigned via transcriptomic analysis. Transcriptomic profiling demonstrates the existence of multiple subtypes of tumor progenitors across timepoints. Strikingly, clonal analysis indicates that each progenitor subtype gives rise to numerous mature tumor cell types, suggesting multiple distinct lineages that contribute to tumor heterogeneity. Through differential expression analysis, we can predict which progenitors are most likely to drive which cell states. By introducing a treatment paradigm into our lineage tracing protocol, we identify tumor progenitor populations that contribute to treatment resistance.
CCRG-01. INFERENCE OF CELL CYCLE REGULATION BETWEEN GLIOBLASTOMA SUBPOPULATIONS IN VIVO TO DRIVE COMPUTATIONAL AND MATHEMATICAL MODELS OF THE CANCER COMPLEX SYSTEM
Authors: Harbour Nicholas , Curtin Lee , Velez Sebastian , Chappell Michael , Hubbard Matthew , Al-Dalahmah Osama , Canoll Peter , Owen Markus , Swanson Kristin
Published: November 2023

Glioblastoma (GBM) is the most aggressive and most common primary malignant brain tumor in adults, with a poor median survival time of 15 months. One of the key challenges in treating GBM is its highly heterogeneous nature, with multiple distinct subtypes that have been shown to occur on both inter- and intra-patient levels. Three main classifications, known as classical/proliferative, mesenchymal and proneural have become commonly demonstrated phenotypes. The cell cycle is a fundamental and highly conserved process that controls faithful division of cells; dysregulation of the cell cycle is known to be a key driver in many cancers. However, how the cell cycle is differently regulated between these subtypes has not been well classified in vivo. We investigate these three GBM subtypes using a recently published single nucleus RNAseq (snRNAseq) data set. We compare cell cycle regulation/dysregulation among these three subtypes using Tricycle, an R/Bioconductor package that utilises dimension reduction via principal component analysis and transfer learning to infer cell cycle position from any snRNAseq data set. We find that the classical GBM subtype has the highest proportion of actively dividing cells (cells in: S/G2/M phases), while the mesenchymal and proneural subtypes have a very low proportion of actively dividing cells. This supports the idea of a proliferation-migration dichotomy between GBM subtypes. We use this proportion of actively proliferating cells to calibrate a minimal spatiotemporal mathematical model for GBM tumor growth that accounts for the differences in cell cycle regulation between these three GBM subtypes.
CCRG-03. KAT5 REGULATES DEVELOPMENTAL TRANSITIONS AND CELLULAR HETEROGENEITY IN AN IN VIVO MODEL OF GLIOBLASTOMA
Authors: Mihalas Anca , Cucinotta Christine , Arora Sonali , Kim Dayoung , Tsukiyama Toshio , Plaisier Christopher , Patel Anoop , Paddison Patrick
Published: November 2023

In solid tumors, G0-like states are likely critical for maintaining developmental hierarchies and cellular heterogeneity and promoting tumor growth/recurrence, yet little is known about tumor G0 states or regulation of their ingress/egress. To discover G0-like states and their regulators for glioblastoma (GBM), we previously performed a genome-wide CRISPR-Cas9 screen in patient-derived GBM stem-like cells (GSCs) for genes that trap cells in G0 when inhibited. We identify the protein acetyltransferase KAT5 as a key regulator of GBM G0 ingress/egress. Here, we show in an in vivo GSC-derived orthotopic xenograft model that KAT5 regulates transcriptional, epigenetic, and proliferative heterogeneity impacting transitions into G0-like states. We show that KAT5 activity suppresses the emergence of non-dividing subpopulations with oligodendrocyte progenitor and radial glial cell characteristics. With regard to chromatin regulation, we show that loss of KAT5 activity alters sites of mixed epigenetic valency (which have both activating and repressive marks in bulk tumor populations) to promote emergence of OPC/RG G0-like populations in tumors. Our data reveal KAT5-associated transcriptional and epigenetic changes in tumors, which indicate that KAT5 activity biases cell state distribution away from OPC and RG-like subpopulations. In addition, loss of KAT5 resulted in a less invasive phenotype and prolonged survival of mice harboring orthotopic xenografts.
CSIG-26. TARGETING HYPOXIC CANCER CELLS IN MEDULLOBLASTOMA
Authors: Kuranaga Yuki , Van Meir Erwin
Published: November 2023

The goal of this study is to thoroughly assess the role of hypoxia-induced transcription factors (HIFs) in MB growth and examine HIF as a potential therapeutic target. We first examined patient MB tumor by IHC and identified scattered areas with expression of HIF1a and HIF2a. We then established orthotopic human MB xenografts in mice and found hypoxic areas throughout the tumors using pimonidazole detection and they expressed both HIF1a, and HIF2a. There are only few observations of hypoxic areas within experimental MB. To explore the impact of HIFs on MB growth, we exposed MB cell lines (ONS-76; Shh and D556; Group 3) to 1% hypoxia in cell culture. We observed a decrease in cell growth, an increase in HIF1a and HIF2a protein expression, activation of HIF targets (Glut-1, VEGF), and a hypoxia-response element-driven luciferase reporter assay. To further examine the role of individual HIF isoforms, we employed CRISPR/Cas9 to knockout (KO) the HIF1a and/or HIF2a genes in ONS76 MB cells. The HIF reporter activity was partially canceled with single HIF-KO and completely abrogated with double KO and double KO reduced cell growth, indicating that both HIF-1 and HIF-2 are having roles for activating transcription and cell growth. Treatment of MB cells with 64B, an arylsulfonamide HIF/p300 inhibitor abrogated reporter activity by both HIF-1 and HIF-2 and reduced expression of hypoxia-induced genes. To investigate the potential of targeting HIF in vivo, we injected mice brains with wild-type and HIF1a/2a-KO ONS-76 cells and monitored their growth and survival. Mice injected with double KO HIF cells exhibited prolonged survival compared to those with parental cells (n = 5, p< 0.01). Further experiments to expand this approach with other MB cell line and test the anti-tumor effects of 64B in mice are ongoing. These findings support targeting HIFs as a novel therapeutic strategy in MB treatment.
CSIG-32. MYC DRIVEN CANCERS ARE DEPENDENT ON CONVERGENT ONCOGENIC PATHWAYS INDUCED BY GENOMIC REARRANGEMENTS AT PVT1
Authors: Bagchi Anindya
Published: November 2023

Plasmocytoma Variant Translocation 1 (PVT1) encodes a lncRNA that is co-amplified with MYC in multiple cancers. PVT1 is also a rearrangement hotspot in diverse human cancers with poor prognoses. However, the functional consequences of PVT1 rearrangement have remained obscure. Here we report that these genomic rearrangements often result in asymmetric enrichment of the proximal half of PVT1 (5’-PVT1) and loss of its distal half (3’-PVT1). Contrary to the general assumption of PVT1 being a non-coding RNA, we identified two distinct transcripts from the 5’-PVT1 and 3’-PVT1 that are capable of coding for functional peptides. A transcript from the retained 5’-PVT1 generates a circular RNA (CircPVT1) which codes for a previously unknown peptide, Firefox (FFX) with oncogenic properties. FFX can synergistically sensitize MYC and augment mTOR signaling in cancer cells. On the other hand, the 3’-PVT1 that is lost during the rearrangement, codes for a micropeptide, Honeybadger (HNB), with tumor-suppressive properties. Inhibition of HNB activates the RAS/MAPK signaling and enhances MYC stability by promoting phosphorylation of MYC Ser62. Molecular docking and biochemical analysis suggest that HNB can interfere with KRAS dimerization, implying its role as an allosteric modulator of RAS/MAPK signaling in cancer. We have previously revealed a strong selection and crucial cooperation between MYC and PVT1 in 8q24+ tumors. Moreover, breakpoints in PVT1 have led to PVT1 promoter-MYC fusions, found on ecDNA, resulting in promiscuous enhancer input to drive MYC transcription. Here we provide evidence that translocation events at the PVT1 locus can result into convergence of MYC, mTOR, and MAPK signaling. Taken together, our study nominates MYC/PVT1 amplification + PVT1 rearrangement as a major driver of cancer pathogenesis, and PVT1 as a critical node that coordinates MYC, mTOR, and MAPK activity in cancer, revealing new regulatory mechanisms that reshape the oncogenic landscape in tumors with genomic rearrangements at PVT1.
RADT-12. GENOMIC CHARACTERISTICS AND CLINICAL OUTCOMES OF STEREOTACTIC RADIOSURGERY FOR COLORECTAL CANCER BRAIN METASTASES
Authors: Gui Chengcheng , Walch Henry , Mueller Kirin , Eichholz Jordan , Khatri Ishaani , Del Balzo Luke , Kemeny Nancy , Imber Brandon , Schultz Nikolaus , Foote Michael , Yaeger Rona , Pike Luke
Published: November 2023

PURPOSE

Brain metastases (BM) from colorectal cancer (CRC) portend a limited prognosis but are poorly understood, both clinically and biologically. This study defined the clinical outcomes and genomic features of CRC BM treated with stereotactic radiosurgery (SRS).

METHODS

Patients with newly diagnosed CRC BM treated with SRS at a single institution between 2009 and 2022 were included. Next-generation targeted sequencing using MSK-IMPACT of at least one intracranial or extracranial tumor was required. Overall survival (OS) was evaluated using Kaplan-Meier analysis. Intracranial progression (IP) and local recurrence (LR) were evaluated using competing risk analysis, accounting for death.

RESULTS

We identified 124 patients with 304 BM, of which, 66 BM received SRS postoperatively. The median prescription was 27 Gy in 3 fractions. Median OS after SRS was 7 months. Poorer KPS, progressive extracranial disease, and lung metastases independently predicted poorer OS. Twelve months after SRS, cumulative incidences of IP and LR were 37% per patient and 6.1% per lesion treated, respectively. Three or more BM at diagnosis independently predicted earlier IP. Biologically effective dose less than the median predicted LR, independent of tumor size. Genomic data were obtained from 68 primary tumors, 63 extracranial metastases, and 33 BM. BM demonstrated significantly greater fraction genome altered, chromosomal instability, and TP53 alterations compared to extracranial metastases and primary tumors. Among patients who had IP, compared to those who had no IP within 6 months, BM contained more frequent alterations in KRAS (56% vs. 43%), SMAD4 (44% vs. 0%), and APC (77% vs. 57%).

CONCLUSIONS

Among CRC BM treated with SRS, OS and IP were correlated with extracranial and intracranial disease burden, and LR was correlated with SRS dose. Genomic characteristics differed between BM and extracranial disease, and between patients who did and did not experience IP. Further investigation of these genomic differences is underway.
RADT-18. PROTON CRANIOSPINAL IRRADIATION WITH CHECKPOINT INHIBITOR THERAPY FOR PATIENTS WITH LEPTOMENINGEAL DISEASE FROM SOLID TUMORS – A SINGLE INSTITUTION CASE SERIES
Authors: Sener Ugur , Webb Mason , Breen William , Laack Nadia , Routman David , Brown Paul , Mahajan Anita , Frechette Kelsey , Leventakos Konstantinos , Dudek Arkadiusz , Markovic Svetomir , Kizilbash Sani H , Campian Jian
Published: November 2023

BACKGROUND

Leptomeningeal disease (LMD) is a devastating complication of cancer with median overall survival (OS) of 3-6 months following diagnosis. Proton craniospinal irradiation (pCSI) is a novel treatment option for LMD, permitting whole neuroaxis treatment with tolerable toxicity and improved efficacy compared to conventional photon whole brain radiation therapy and as needed focal spine radiotherapy. Despite this, patients experience progression and succumb to LMD. Addition of systemic therapy to pCSI may improve outcomes.

METHODS

In this single institution retrospective case series, we report feasibility of combination treatment with pCSI and immune checkpoint inhibitor (ICI) in patients with LMD from solid tumors.

RESULTS

Three patients were treated with pCSI (30 Gy in 10 fractions) and ICI. The first patient developed LMD related to large cell neuroendocrine carcinoma of lung primary, diagnosed by imaging and cytology, having previously undergone resection and stereotactic radiosurgery for brain metastases. Clinical and radiographic improvement was noted following pCSI, bevacizumab, and pembrolizumab therapy. Patient experienced disease progression and passed away only after ICI was held due to hypophysitis, with 6-month OS. The second patient developed LMD related to BRAF V600E mutant melanoma, diagnosed by imaging and cytology, having previously undergone ICI and BRAF-targeted therapy. Following pCSI, relatlimab, nivolumab, and BRAF-targeted therapy, the patient remains alive 7 months after LMD diagnosis despite radiographic progression treated with carboplatin, paclitaxel, intrathecal IL-2, ipilimumab, and bevacizumab. The third developed LMD related to BRAF-wildtype melanoma, diagnosed by imaging, having previously received ICI. Patient underwent pCSI followed by ipilimumab and nivolumab, progression-free 5 months after LMD diagnosis.

CONCLUSION

Addition of systemic therapy to pCSI is feasible for patients with LMD. Combination of ICI and pCSI may confer additional survival benefit, even among patients with prior exposure to ICI. These initial promising results warrant prospective evaluation.
RADT-25. IMPACT OF 18F-DOPA PET ON RADIATION TREATMENT PLANNING FROM PHASE II STUDY OF SHORT COURSE HYPOFRACTIONATED PROTON BEAM THERAPY FOR ELDERLY PATIENTS WITH GLIOBLASTOMA
Authors: Laughlin Brady , Pafundi Deanna , Buras Matthew , Ashman Jonathan , Bendok Bernard , Laack Nadia , Breen William , Ruff Michael , Mahajan Anita , Mrugala Maciej , Sio Terence , Uhm Joon , Yang Ming , Brinkmann Debra , Brown Paul , Hu Leland , Vora Sujay
Published: November 2023

PURPOSE

18F-DOPA is sensitive/specific for identifying areas of biologically aggressive disease for glioblastoma. We report the impact of 18F-DOPA on radiation treatment planning from a phase II study.

METHODS

Gross target volume (GTV) was defined by the boolean of high-risk PET (tumor/normal brain SUV > 2.0) and MRI T1 contrast enhancement (MRI-CE) including surgical cavity. The clinical target volume (CTV) included the GTV with 1cm margin. Using proton beam therapy, GTV ≤ 65 cc was treated with 25 (CTV), 30 (MRI-CE), and 35 (PET) GyE over 5 fractions with a simultaneous integrated boost. GTV > 65 cc received 30 (CTV), 35 (MRI-CE), and 40 (PET) GyE over 10 fractions. Radiation field design was compared to traditional 1.5cm CTV margin on MRI-CE.

RESULTS

Between May 2019 and October 2021, 39 patients were treated. The median MRI-CE tumor diameter was 5.2cm. The median PET volume was 7.9cc (range 0–64.9cc). The median MRI-CE volume was 35.1cc (range 8.6–114cc). High-risk PET was contained within: MRI-CE 18/39 (46%), MRI-CE + T2W FLAIR 13/39 (33%), MRI-CE + T2W FLAIR + outside GTV 4/39 (10%), outside GTV 2/39 (5%) and no uptake 2/39 (5%). Utilizing this planning technique, there was a 26% volume reduction in CTV to traditional 1.5 cm margin on MRI-CE. PET imaging in treatment planning allowed inclusion of high-risk disease that would have been excluded on traditional CTV in 23% of cases (range 1.6-33.8cc). PET was more predictive [HR 1.03 (95% CI 1.01, 1.05) p = 0.002] than MRI [HR 1.01 (95% CI 1.00, 1.03) p = 0.02] for death with each cc increasing risk of death by 3.1%.

CONCLUSIONS

The incorporation of 18F-DOPA in treatment planning yields a more targeted approach with reductions in both normal brain treated and risk of geographic miss compared to traditional CTV margins.
RADT-29. TARGETING ANDROGEN RECEPTOR FOR GLIOBLASTOMA: A NOVEL RADIOSENSITIZING THERAPY THROUGH TGF-Β/LIF/STAT3 PATHWAY AND IMMUNOMODULATION
Authors: Khan Rubayat , Zhao Nan , Zhang Chi
Published: November 2023

In the search for more effective treatments for glioblastoma (GBM), a primary brain malignancy, we explored the synergistic effects of androgen receptor antagonists (ARAs) and radiotherapy (RT). Prior research indicated that ARA treatment alone improved survival in GBM mouse models, primarily through the suppression of glioma cancer stem cells. Our recent investigations aimed to ascertain the radiosensitizing effects of ARAs when combined with RT. Initial in vitro experiments, using proliferation assays on cultured GBM cells, showed only mild radiosensitizing effects. ARAs, however, induced apoptosis, enriched the G2/M phase in cell cycling, and decreased expression in numerous DNA repair genes, which were confirmed through RNA sequencing and TCGA database analyses. Additionally, Western blotting revealed that ARAs modulated SMAD2/3 phosphorylations differentially in c-terminal and linker domains in the TGF-β pathway and suppressed LIF-STAT3 signaling. This intricate mechanism involving the alteration of key cellular signaling pathways led us to hypothesize that ARAs may potentiate RT in vivo. To validate this hypothesis, we conducted in vivo studies using an orthotopic GBM mouse model. Substantial synergy was observed between ARAs and brain RT, with combined ARA and RT treatment achieving 100% long-term survival and establishing immune memory, a significant increase compared to <50% survival for the ARA only group and 0% for the RT only group. Notably, we identified significant immunostimulating effects within the tumor microenvironment and systemically, as determined by immunohistochemistry and flow cytometry on peripheral blood and spleen, respectively. Our findings demonstrate that although ARAs show mild radiosensitizing effects on GBM cells in vitro, they significantly synergize with RT in vivo, via alterations in TGF-β/LIF/STAT3 signaling pathways which have been known to influence immunomodulation. The local and systemic immunomodulatory effects demonstrated in our studies by ARA treatment warrant further study combining ARA with immunotherapeutics.
RADT-34. CLINICAL OUTCOMES OF LOCALISED AND METASTATIC CENTRAL NERVOUS SYSTEM HAEMANGIOPERICYTOMAS/SOLITARY FIBROUS TUMOURS – A SINGLE INSTITUTION EXPERIENCE
Authors: Venkatasai Jeyaanth , Manik Vishal , Chia Kazumi , Swampillai Angela , Al-Salihi Omar , Brazil Lucy
Published: November 2023

BACKGROUND/OBJECTIVE

Central nervous system (CNS) haemangiopericytomas (HPC) or solitary fibrous tumours (SFT) are rare aggressive tumours. Surgery is the primary modality of treatment, however, often followed by postoperative radiotherapy due to high tendency for local recurrence. Although rare, extracranial metastases to several sites have been described. We aim to report our institutional experience in managing these rare tumours.

METHODS

Patients with central nervous system HPC/SFT who underwent surgical resection from 2012 to 2022 were included in the study. Data collected included patient demographics, tumour characteristics, treatment details (including primary surgery, radiotherapy and treatment for relapse) and clinical outcomes.

RESULTS

Five patients were included in this study. All were women and their mean age at diagnosis was 43 years. Four patients presented with intracranial disease and one with cervico-thoracic spine disease. All patients had undergone primary surgery and gross total resection was achieved in two patients. Two patients had grade 1, one with grade 2 and two with grade 3 HPC. Four patients received radiotherapy (median dose 60Gy) and one was on imaging surveillance after surgery. Three patients had relapsed – one with locoregional relapse only, one with distant (liver and bone) relapse and other with locoregional and distant (lung and bone). Time to relapse were 192, 39 and 120 months respectively. Stereotactic radiotherapy was used to treat local relapse in posterior fossa and dura of cervical spine, and metastatic relapse in lung with a stable radiological response. One patient with a painful destructive bone metastases was treated with palliative radiotherapy with good pain control. Four patients were alive at the time of the study, and one was lost to follow up.

CONCLUSION

We present our institutional experience in management of localised and metastatic HPC/SFT. Stereotactic radiotherapy could be considered an effective treatment modality for small volume relapse of HPC.
RADT-40. FINAL RESULTS OF THE PROSPECTIVE PHASE 2 MARCIE TRIAL: EFFICACY AND TOXICITY OF POSTOPERATIVE BIMODAL RADIOTHERAPY WITH C12-BOOST IN PATIENTS WITH ATYPICAL MENINGIOMAS FOLLOWING SUBTOTAL RESECTION
Authors: Deng Maximilian , Hinz Felix , Karger Christian , Sievers Philipp , Eichkorn Tanja , Meixner Eva , Hörner-Rieber Juliane , Lischalk Jonathan , Seidensaal Katharina , Jungk Christine , Unterberg Andreas , Wick Antje , Wick Wolfgang , von Deimling Andreas , Sahm Felix , Bernhardt Denise , Combs Stephanie , Herfarth Klaus , Debus Jürgen , König Laila
Published: November 2023

Radiotherapy is recommended by current EANO guidelines for patients with atypical meningiomas (WHO grade 2) following subtotal resection. While meningiomas are generally considered radioresistant, novel radiotherapeutic modalities using carbon ions present an increased relative biological effectiveness (RBE) compared to photons, while reducing the radiation exposure for adjacent organs at risk by exploiting the Bragg peak. Our prospective phase 2 trial investigated bimodal radiotherapy using a carbon-ion boost in patients with atypical meningiomas following subtotal resection. A total of 33 patients were enrolled from 07/2012 until 07/2020. The study was prematurely terminated in 07/2020 after recruiting 33 of the initially planned 40 patients due to one grade 5 toxicity. Study treatment comprised a carbon ion boost (18 Gy [RBE] in 6 fractions) targeted to the macroscopic tumor in combination with photon radiotherapy (50 Gy in 25 fractions). The primary endpoint was progression-free survival, and secondary endpoints included overall survival, safety and toxicities. With a median follow-up of 42 months, the 3-year estimates of progression-free survival (PFS), local PFS and overall survival were 80.3%, 86.7% and 89.8%, respectively. Radiation-induced contrast enhancements (RICE) was encountered in 45%, particularly in cases of periventricularly-located meningiomas. Patients exhibiting (transient) RICE were either asymptomatic (40%) or presented immediate improvement (47%) after the administration of corticosteroids or/and bevacizumab. Treatment-associated complications were encountered in 2 patients with radiation necrosis: 1 patient died due to postoperative complications in an external center after resection of radiation necrosis, and the other received an aggregated 21 cycles of bevacizumab. As a result, the study was prematurely terminated. Post-hoc integrated molecular-morphologic scoring identified patients at risk of tumor progression. Study treatment may be considered for selected patients with molecular high-risk meningiomas to achieve high tumor control rates. Patients’ risk to develop radiation-induced side effects depends on the location of the treatment volume.
RADT-44. LONG-TERM OUTCOMES WITH REDUCED-DOSE WHOLE BRAIN RADIOTHERAPY AND A STEREOTACTIC RADIOSURGERY BOOST FOR PRIMARY CNS LYMPHOMA
Authors: Foreman Bronwen , Mullikin Trey , Floyd Scott , Kelsey Chris , Patel Mallika , Peters Katherine , Kirkpatrick John , Reitman Zachary , Vaios Eugene
Published: November 2023

BACKGROUND

Primary central nervous system lymphoma (PCNSL) is an aggressive diffuse large B-cell lymphoma. Treatment approaches are historically associated with neurotoxicity, particularly with high-dose whole-brain radiotherapy (WBRT). We hypothesized that reduced dose-WBRT (rd-WBRT) followed by a stereotactic radiosurgery (SRS) boost could provide durable disease control without significant adverse effects.

METHODS

We retrospectively reviewed PCNSL patients treated with rd-WBRT plus an SRS boost at Duke University between 2008 and 2021. Progression-free survival (PFS) and overall survival (OS) were estimated using competing risk and Kaplan Meier methods.

RESULTS

We identified 23 patients with pathologically confirmed PCNSL. Median age at diagnosis was 69 years (Q1Q3:52–74) and median KPS was 80 (Q1Q3:70–80). Median follow-up was 21 months. Median doses for rd-WBRT and SRS were 23.4Gy (Q1Q3:23.4–23.4) and 12Gy (Q1Q3:12–12.5), respectively. The cumulative incidence of intracranial progression at two years was 23% (95%CI:8-42). Six patients (26%) developed distant radiographic progression while two patients (9%) developed both distant and local progression. Ten patients (44%) were alive without progression at last follow-up. By Kaplan Meier estimate, the two-year overall survival was 69% (95%CI:46-84). There were no reported grade 3+ radiation-induced toxicities.

CONCLUSIONS

The combination of rd-WBRT with an SRS boost appears well-tolerated with durable intracranial control. This approach represents a treatment option for select patients, such as those with progressive or refractory disease. Further prospective studies are needed to validate these findings and determine whether this approach could be incorporated into consolidation strategies.
RADT-48. RADIATION MYELOPATHY AFTER STANDARD DOSE RADIATION: POTENTIAL RADIATION SENSITIZING EFFECTS OF SYSTEMIC THERAPY
Authors: Hazy Allison , Grills Inga , Ogaily Mohammed , Stender Michael , Rogers Lisa R
Published: November 2023

Radiation myelopathy is an uncommon adverse effect of spinal irradiation. It is especially rare following conventional palliative fractionation regimens for vertebral metastasis. We present two cases of delayed thoracic radiation myelopathy in patients with breast cancer. In both cases, palliative radiation of 30 Gy in ten fractions was administered to thoracic spinal metastases. Neither patient received concurrent systemic therapy. One began trastuzumab emtansine nine days after finishing radiation and the other started palbociclib three months afterwards, which was switched to capecitabine at disease progression. Each patient developed progressive leg weakness and numbness, ten months following radiation and eleven months following radiation (four weeks following capecitabine), respectively. MRI showed edema and focal contrast enhancement within the radiation field in each. Both were treated with high-dose corticosteroid, vitamin E, and pentoxifylline. Neither patient returned to their neurologic baseline and remain with significant deficits, requiring assistance with ambulation. Serial MRIs revealed eventual reduction in cord enhancement and edema, followed by cord atrophy in one case. The cumulative radiation dose of 30 Gy is typically within the safety tolerance of the spinal cord, so it is speculative if post-radiation systemic therapy played a role in the development of myelopathy. The timing is particularly convincing in the patient who developed symptoms within four weeks of starting capecitabine. These cases are similar to recently reported instances of radiation myelopathy after standard dose spinal radiation followed by chemotherapy or immunotherapy. Recognition of the potential radiation sensitizing effects of systemic therapy should lead clinicians to consider radiation myelopathy early if spinal cord symptoms develop and to consider the timing of initiation of potential sensitizing drugs when spinal radiation has been given.