bluuebunny/crossref_metadata_2025_split huggingface dataset:
CNSC-40. GTP SIGNALING PATHWAY PROMOTES NHEJ REPAIR BY INDUCING NUCLEAR ACTIN POLYMERIZATION IN GLIOBLASTOMA
Authors: Zhou Weihua 
Published: November 2024

Abstract

OBJECTIVES
We recently identified that GTP promotes non-homologous end joining (NHEJ) by triggering a GTP-Rac1-PP5-Abi-1/S323 cascade and we sought to define the molecular mechanisms.

METHODS
Crispr/Cas9, CDNA overexpression and immunoblot were used to modulate and confirm protein levels. Cellular fractionation and immunofluorescence (IF) were used to determine the localization of proteins. Laser micro-irradiation was used to induce DNA damage and monitor the recruitment of DNA repair proteins.

RESULTS
We found that GTP-activated protein Rac1 and Abi-1, the two key components of the newly identified pathway, shuttled into the nucleus post-RT in glioblastoma (GBM) cells. These effects were further enhanced by the GTP precursor guanosine but blocked by GTP depletion. Furthermore, Abi-1 and Rac1 accumulated in the nucleus of the cells expressing constitutively active Rac1 but not dominant negative Rac1 after RT, which suggests that Rac1/Abi-1 nuclear translocation is Rac1 activity dependent. We previously discovered that GTP-Rac1 promotes DNA repair by facilitating the dephosphorylation of Abi-1 (S323). Here, we discovered that dephosphomimetic Abi-1 (S323A) but not phosphomimetic Abi-1 (S323D) shuttled into nucleus after RT. Because Rac1 canonically binds to Abi-1 and promotes actin polymerization in the cytosol, we next wanted to determine if RT-induced nuclear Rac1/Abi-1/S323A could enhance nuclear actin polymerization, which could enhance NHEJ repair. We found that Abi-1/S323A but not Abi-1/S323D increases nuclear filament actin formation post-RT and activating the GTP-Rac1-Abi-1/S323A axis (through guanosine supplementation, expression of constitutively active Rac1 or expression of dephosphomimetic Abi-1/S323A) enhanced the recruitment and stability of KU80 at sites of DNA damage, which could be blocked by actin polymerization inhibitor cytochalasin D. Furthermore, inhibiting actin polymerization overcame radiation resistance in GBM cells with an active GTP-Rac1-Abi-1/S323A axis.

CONCLUSIONS
GTP-Rac1-PP5-Abi-1/S323 cascade promotes NHEJ repair by inducing the nuclear assembly of filament actin and disrupting this regulation could improve treatment responses in GBMs.
CNSC-64. BEYOND THE LOCAL TUMOR MICROENVIRONMENT: CHARACTERIZING CHANGES TO NEURONAL ACTIVITY INDUCED BY PEDIATRIC HIGH-GRADE GLIOMA
Authors: Farnsworth Hannah , Pinter Meghan , Carleton Elana , Franklin Alexis , Gentry Kaylee , Davis Rachel , Hoffman Hannah , Venkatesh Humsa 
Published: November 2024

Abstract
Bidirectional electrochemical signaling between neurons and tumor cells is emerging as a critical regulator of pediatric high-grade glioma (HGG) pathology. Neuron-tumor interactions are known to induce local neuronal hyperactivity. However, recent work tracing the projections of these neuron-tumor networks revealed that HGG neuronal recruitment extends beyond the local tumor microenvironment (TME). These findings suggest that tumor-induced hyperexcitability may spread beyond the local TME and drive brain-wide circuit-level changes. To elucidate how non-tumor innervated brain regions are affected by TME hyperactivity we first characterized neuronal hyperactivity induced by a cortical patient-derived pediatric high-grade cell line in vitro on human iPSC-derived neurons. In vitro calcium imaging experiments demonstrated an increase in the number of calcium fluctuations in glioma co-cultured neurons. In parallel, multi-electrode recordings revealed increased population spiking activity and amplitude in neurons co-cultured with glioma cells. We then xenografted these HGG cells into the prefrontal cortex of mice and performed whole brain-clearing and cFos staining on tumor-bearing vs saline-injected control samples. As cFos is an immediate early gene activated by neuronal activity, we utilized the density of cFos expression as a readout-out of neuronal activation in our atlas-aligned segmented brain section analyses. We expectedly observed increased cFos expression within the ipsilateral primary and secondary motor region, which collectively comprise the local TME. Interestingly, we additionally observed elevated cFos in non-tumor bearing brain regions on both the ipsilateral and contralateral hemispheres, largely in layer 2/3 cortical neurons. These neurons form extensive cortico-cortical projections, and we coincidingly observed increased cFos expression in known cortical projection targets of the prefrontal xenograft location, such as somatosensory, visual, and retrosplenial cortices. Our findings suggest that tumor-induced neuronal hyperactivity extends beyond the local TME in a brain-wide manner and potentially follows established neuronal circuits, rendering these connected regions vulnerable to alterations in neuronal activity.
STEM-12. A NEURONAL STEM-LIKE PHENOTYPE IN GRADE 4 IDH-MUTANT ASTROCYTOMA WITH CDKN2A/B LOSS IS ASSOCIATED WITH CUX2 DEFICIENCY
Authors: Grief Dustin , D’Angelo Fulvio , Caruso Francesca , Flick Matthew , Sereduk Christopher , Ceccarelli Michele , Hu Leland , Loftus Joseph , Tran Nhan , Ensign Shannon Fortin 
Published: November 2024

Abstract
Diffuse gliomas represent the most common type of primary adult malignant brain tumor historically diagnosed and graded from histologic criteria alone. Gliomas harboring isocitrate dehydrogenase (IDH) 1 or 2 mutations are associated with lower grade tumors and portend a favorable prognosis relative to IDH-wildtype glioma. However, the loss of CDKN2A/B in IDH-mutant astrocytoma confers an aggressive high grade phenotype and is the strongest implicated molecular alteration associated poor clinical survival, thus is now sufficient to define a grade 4 tumor regardless of histologic grade. However, there remains no effective therapies targeted at molecular subgroups in aggressive gliomas to date. Here, we sought to elucidate the biologic pathways and functional outcomes associated with the acquisition of high-grade behavior under loss of CDKN2A/B in IDH-mutant astrocytoma to inform future therapeutic strategies. We analyzed a cohort of patient IDH-mutant astrocytomas with RNA sequencing data and found the increased expression of regulators of embryonic nervous system development and signaling concurrent with CDKN2A/B loss. Using grade 4 IDH-mutant astrocytoma patient-derived (PDX) and cell-lines harboring CDKN2A/B homozygous deletion, we stably re-expressed p14ARF, p15INK4B, and p16INK4A using a Tet-inducible system. IDH-mutant cell lines with re-expression of p14, p15, or p16 displayed differential transcription factor activation, impaired neurosphere capability, decreased colony formation, and lower neurosphere proliferation. Intriguingly, RNA-seq data revealed CUX2, a transcription factor known to control neuronal precursor behavior, as the likely candidate regulating the differential expression profile across CDKN2A/B status. We observed increased CUX2 expression in cell lines stably re-expressing p14, p15, and p16. We validated the CUX2 signature across publicly available datasets of IDH-mutant astrocytoma where CUX2 expression negatively correlated with loss of CDKN2A/B in patient tumors. Together our work suggests CUX2 deficiency in IDH-mutant astrocytoma with CDKN2A/B deletion enables an increased neuronal stem-like phenotype in these grade 4 tumors.
STEM-16. EXPLORING THE ROLE OF HYPOXIA AND MACROPHAGES ON GLIOBLASTOMA QUIESCENCE AND STEMNESS AS MEDIATORS OF RADIORESISTANCE
Authors: Pradhan Puja , Agudelo Luis , Karwacinski Victor , Constante Nicole , Olson Cheryl , Li Jiabo , Shih Ling-kai , Carneiro-Lobo Tatiana , Brat Daniel 
Published: November 2024

Abstract
Our ultimate goal is to identify, characterize and therapeutically target the glioma cell population that is responsible for treatment resistance and recurrence following chemoradiation. Two cell types that may have overlapping phenotypes and are known to influence radioresistance are 1) quiescent cells and 2) glioblastoma (GBM) stem cells (GSCs). The extent of overlap between these populations is unknown as are the influence of hypoxia and immune cells on their radioresistant properties. We have shown that hypoxia and co-culturing with THP-1 macrophages dramatically increases the percentage of GSCs. Using the Fluorescent Ubiquitination-based Cell Cycle Indicator (FUCCI) system expressed in patient-derived gliomas, we used flow cytometry to distinguish cells based on their cell cycle status (G1/G0 and G2/M) and classified them as quiescent (high p27, low Ki67) or GSC (high CD133/CD44 co-expression). We found that the fraction of cells in G0 expressed high p27 and low Ki67, indicating cell cycle suppression and low proliferation, respectively. G0 glioma cells also contained a high percentage of GSCs, but GSCs were also distributed in G1 and G2/M. Following exposure to hypoxia, flow cytometry of FUCCI GBM cells showed an increase of cells in G0. After 3 Gy radiation under normoxic conditions, GBM cells demonstrated a shift to increased levels of G2/M cells compared to non-irradiated cells. In hypoxia, however, GBM cells sustained their population of cells in G0 and did not exhibit such cell cycle shifts. Our results indicate that both hypoxia and macrophages cause GSC enrichment and that hypoxia increases the proportion of quiescent cells in G0. Additional study is necessary to determine the extent of overlap between the GSCs and quiescent cells and to identify the intrinsic cell properties that drive tumor recurrence.
STEM-20. MULTI-OMICS OF HUMAN MEDULLOBLASTOMAS AND GENETIC LINEAGE TRACING IN VIVO INDICATE CELLULAR PLASTICITY
Authors: Yu Bohyeon , Jung Jangham , Diaz Aaron 
Published: November 2024

Abstract
Recent single-cell studies implicate the glutamatergic lineage of the rhombic lip (RL) as the origin of group (G) 3/4 medulloblastomas (MBs) and a stalled differentiation program as underlying malignant transformation. While the cellular compositions of G3/G4 MBs are consistent with a truncated neurodevelopmental hierarchy, it is unknown whether G3/G4 MBs exhibit cellular plasticity. We profiled tumors from 38 patients who underwent surgery for MB at UCSF via single-nucleus RNA sequencing (snRNA-seq). We developed in vivo genetic lineage-tracing systems with a single-cell readout and applied them to patient-derived G3 MB xenografts. High-complexity lentiviral barcode libraries were transduced into D283 and D425 patient-derived cell lines. Barcoded cells were injected into the brains of immunocompromised mice. Both preimplantation barcoded cultures and mature tumors were profiled by single-cell RNA-sequencing (scRNA-seq). This captured both endogenous RNA and barcode transcripts. RL neuro-developmental cell-type labels were transferred from public single-cell data from fetal cerebellum to single-cell data from our patient samples and xenograft models. Remarkably, xenografts produced similar cell types, in similar proportions to those found in human MBs. Moreover, the distribution of cell types found in the xenografts was conserved at the level of individual clones, indicating cell-intrinsic regulation of tumor composition. We developed approaches to use barcode and expressed point-mutation data to reconstruct intra-clone genetic phylogenies. We then used the transcriptional phenotypes of the observed cells to infer ancestral phenotypes for each clone’s phylogeny. We compared clade to sub-clade differences in cell type against the neural-developmental hierarchy found in the fetal RL. We observed significant rates of dedifferentiation events from unipolar brush-like cells to RL-progenitor phenotypes. These studies indicate that G3 MB cellular composition is homeostatic and conserved at the level of individual clones. Yet, these tumors exhibit plasticity, as has been observed in other brain cancers such as glioblastoma.
RADT-01. PRE-OPERATIVE SINGLE FRACTION VERSUS FRACTIONATED STEREOTACTIC RADIOTHERAPY: A SINGLE-INSTITUTION ANALYSIS OF 299 RESECTED METASTASES
Authors: Perlow Haley , Luu Sydney , Reddy Sohil , Bradshaw Jared , Hennings Sarah , Matsui Jennifer , Klamer Brett , Upadhyay Rituraj , Oliver Alexandria , McGregor John , Lonser Russell , Prevedello Daniel , Elder James , Wu Kyle , Prabhu Roshan , Zhu Simeng , Singh Raj , Beyer Sasha , Grecula John , Blakaj Dukagjin , Thomas Evan , Raval Raju , Palmer Joshua 
Published: November 2024

Abstract
The treatment standard for patients with large or symptomatic brain metastases and limited intracranial disease is surgical resection followed by post-operative (post-op) stereotactic radiosurgery (SRS). The multicenter PROPS-BM cohort showed how pre-operative (pre-op) SRS may lead to a reduced incidence of radiation necrosis (RN), local failure (LF), and meningeal disease (MD) compared to historical controls. Fractionated treatments can deliver a higher biological effective dose and may reduce the incidence of LF and MD. We hypothesize that pre-op fractionated stereotactic radiation therapy (FSRT) will reduce the incidence rate of RN, MD, and LF when compared to patients who receive pre-op SRS. Patients who had surgical resection and pre-operative radiation to at least one brain metastasis at a single institution were retrospectively analyzed. Outcomes were evaluated on a per-lesion basis. The primary outcome was a composite endpoint defined by 1) LF, 2) MD, and/or 3) Grade 2 or higher (symptomatic) RN. 260 patients with 299 resected brain metastases were eligible for analysis. 64 metastases received SRS and 235 metastases received FSRT. 38 patients had multiple metastases resected pre-operatively. The median gross tumor volume was 4 ccs for SRS and 10 ccs for FSRT (p&lt;0.001). Overall, 4 (6.3%) SRS and 6 (2.6%) FSRT patients experienced LF. 4 (6%) SRS and 21 (8.9%) FSRT patients experienced Grade 2 or higher RN. 3 (4.7%) SRS and 11 (4.7%) FSRT patients were diagnosed with MD. 14% of both SRS and FSRT patients experienced the composite endpoint. There were no statistically significant differences in outcome between these two treatment groups. In our study, pre-op SRS and FSRT both appear to be safe and effective options to treat resectable brain metastases. It is important to prospectively compare pre-op SRS and FSRT in matched cohorts to assess any differences in treatment efficacy and toxicity.
RADT-15. THE ROLE OF STEREOTACTIC RADIOSURGERY IN WHO GRADE II MENINGIOMAS: RESULTS FROM A LARGE EUROPEAN MULTICENTER STUDY
Authors: Santacroce A , Tuleasca C , Liščák R , Kollova A , Motti E , Lindquist C , Radatz M , Frischer J , Lippitz B , Álvarez R Martínez , Skeie B Sandvei , Nicolato A , Longhi M , Unger F , Sabin I , Mindermann T , Bundschuh O , Horstmann G A , van Eck A T C , Nakamura M , Steiger H -J , Ewelt C , Alsofy S Zafy , Lewitz M , Régis J , Muacevic A , Hofmann T , Ehret F , Picozzi P , Faedo S , Franzini A , Masaranov S , Greve Tobias 
Published: November 2024

Abstract

BACKGROUND
This study evaluates the outcomes of WHO grade II meningiomas treated with stereotactic radiosurgery (SRS) using a large, multi-institutional European database. We aim to investigate the long-term tumor control rate and morbidity associated with SRS.

METHODS
Data from 355 consecutive patients treated between 1992 and 2022 at 16 European radiosurgery centers were retrospectively analyzed. After excluding 40 patients due to loss to follow-up, results from 315 patients were included. Clinical and imaging data were independently collected by each center and uniformly entered into a multicenter database.

RESULTS
The median age of patients was 56 years, with 54% being female. The median follow-up duration was 46.3 ± 36.9 months. Tumors had prior surgical treatment and biopsy in 99% and 1% of cases, respectively. Tumors received previous radiotherapy or SRS in 27.4% of cases. SRS was performed due to local progression in 89.6% of cases, residual tumor in 6.4%, and distant progression in 4.0%. SRS characteristics included a median target volume of 5.1 cm³ and a median margin dose of 16 Gy (53.5% isodose). The 3-year local control rate was 72.0%, with a progression-free survival rate of 66.6% and an overall survival rate of 89.7%. Transient and permanent morbidity rates were 6.4% and 3.5%, respectively. Multivariate analysis identified previous radiotherapy and age as significant factors influencing these outcomes.

CONCLUSIONS
This study is the largest to date on SRS in WHO grade II meningiomas. Our data shows that SRS is a viable and safe treatment option for residual and recurrent WHO grade II meningiomas
RADT-33. GAMMA KNIFE RADIOSURGERY FOR ORBITAL CAVERNOUS HEMANGIOMA: A SYSTEMATIC REVIEW AND SINGLE-ARM META-ANALYSIS
Authors: Chen Hsien-Chung , Franklin Brodus , Punukollu Anurraag , Pineda Felipe , Palavani Lucca 
Published: November 2024

Abstract
Gamma knife radiosurgery (GKRS) for orbital cavernous hemangioma (OCH) has emerged as a promising method due to its significant clinical improvement and low incidence of complications. This study aimed to evaluate the safety and efficacy of GKRS for the treatment of OCH. Following the PRISMA framework, we searched PubMed, Cochrane Central, and Embase for studies reporting outcomes of GKRS for OCH, including complications, visual improvement, proptosis, tumor reduction rate, and tumor progression rate. From 1856 search results, six studies with 100 patients were included. Only five minor complications related to GKRS were reported, including three with orbital pain and two with periorbital chemosis, resulting in a complication rate of 13% (95% CI: 7% - 25%). Visual acuity and visual field improvement rates after GKRS were 80% (95% CI: 63% - 96%) and 71% (95% CI: 47% - 95%), respectively. Proptosis improved in 94% of cases (95% CI: 83% - 100%). The tumor reduction rate was 77% after GKRS (95% CI: 69% - 85%). In conclusion, GKRS for OCH appears to be a safe technique, as evidenced by the rate of clinical improvement and radiological improvement. However, studies are limited by the absence of a control group, and additional studies are needed to evaluate the relative efficacy of GKRS compared with alternative surgical modalities for OCH.
CTIM-03. IMMUNE CHECKPOINT INHIBITOR NIVOLUMAB IN PEOPLE WITH RECURRENT SELECT RARE CNS CANCERS: RESULTS OF INTERIM ANALYSIS IN A NON-HEAVILY PRETREATED COHORT
Authors: Argao Lorenzo , Yuan Ying , Wall Kathleen , Kunst Tricia , Chambers Claudia , Vera Elizabeth , Huguely Caitlin , Watanabe Masashi , Grajkowska Ewa , Abdullaev Zied , Acquaye-Mallory Alvina , Aldape Kenneth , Anderson Brita , Boris Lisa , Bota Daniela A , Briceno Nicole , Burton Eric , Choi Anna , Cimino P J , Giglio Pierre , Kamiya-Matsuoka Carlos , Kumthekar Priya U , Levine Jason , Lindhorst Scott M , Ozer Byram , Panzer Marissa , Pillai Tina , Polskin Lily , Pratt Drew , Quezado Martha , Tweneboah-Koduah Renee , Wu Jing , Armstrong Terri S , Gilbert Mark R , Penas-Prado Marta 
Published: November 2024

Abstract

BACKGROUND
There is a paucity of salvage therapies for patients with rare CNS tumors. Nivolumab (PD-1 inhibitor) is approved for a variety of systemic cancers. We developed a multisite basket Phase II trial to evaluate Nivolumab for patients with recurrence of one of 12 selected rare CNS cancers. Efficacy is measured by Disease Control Rate (DCR; confirmed CR/PR or durable SD for ≥ 6 months) in 2 cohorts: heavily and non-heavily pretreated (≥ 3 prior therapies, vs. ≤ 2; including radiation and/or standard or experimental drugs). Cohort 1 has been completed. We report efficacy results and safety data of a preplanned interim analysis in Cohort 2 (non-heavily pretreated).

METHODS
In addition to progressive disease, eligibility includes available tumor tissue; age ≥ 18; KPS ≥ 70; no steroids at trial entry. Planned accrual: 75 in each cohort. Nivolumab dose: 240 mg IV every 2 weeks (4 doses), followed by 480 mg every 4 weeks (14 additional doses). Interim analysis was planned when the sample size reached 32 in each cohort.

RESULTS
As of December 1, 2023, among 27 evaluable patients treated in the non-heavily pretreated cohort, 10 achieved SD ≥ 6 months (DCR 37%; 95% CI 19.4%,57.6%) – 6 high-grade meningiomas; 1 each: myxopapillary ependymoma with lung metastases; solitary fibrous tumor, gliomatosis (astrocytoma IDH mutant WHO grade 2), chordoma. A total of 56 Grade 3-5 AEs occurred; 13 (Grade 3-4) related to nivolumab, including Grade 3 gait disturbance (3); cerebral edema, cognitive disturbance, colitis, headache, hypotension, hypoxia, lymphopenia, pain, and pruritus (1 each), and one Grade 4 cerebral edema. The three Grade 5 AEs were disease-related.

CONCLUSION
Preliminary efficacy analysis exceeded the “go” boundary (i.e., &gt; 5 responders) in the non-heavily pretreated cohort. Nivolumab showed an acceptable safety profile. Cohort 2 will continue to complete a planned accrual of 75 patients.
CTIM-19. A PHASE 1, SAFETY LEAD-IN AND RANDOMIZED, OPEN-LABEL, PERIOPERATIVE STUDY OF VORASIDENIB COMBINED WITH PEMBROLIZUMAB IN RECURRENT OR PROGRESSIVE ENHANCING IDH-1 MUTANT GLIOMA: TRIAL IN PROGRESS
Authors: Wen Patrick , de la Fuente Macarena , Kumthekar Priya , Peters Katherine , Clarke Jennifer , de Groot John , Arrillaga-Romany Isabel , Puduvalli Vinay , Mellinghoff Ingo , Chong Robert , Jain Payal , Barboux Valentine , Chisamore Michael , Abshire Michelle , Mahboub-Johnson Paria , Hassan Islam , Knipstein Jeffrey , Cloughesy Timothy 
Published: November 2024

Abstract

BACKGROUND
Vorasidenib (VOR) is an oral, brain-penetrant dual inhibitor of isocitrate dehydrogenase 1/2 mutant (mIDH1/2) enzymes. VOR is being investigated in a phase 3 study in residual or recurrent grade 2 non-enhancing gliomas, in which interim analysis showed VOR significantly improved progression-free survival and delayed time to next intervention. A prior neoadjuvant perioperative study in recurrent, non-enhancing grade 2/3 gliomas showed that VOR treatment was associated with interferon signal activation and increased T-cell infiltration, suggesting 2-hydroxyglutarate suppression may prime the tumor immune microenvironment for immune checkpoint blockade. This study (NCT05484622) evaluates the safety and tolerability of VOR+pembrolizumab to determine the recommended combination dose (RCD) of VOR (safety lead-in phase) and evaluates CD3+ T-cell infiltration in tumors following a 28-day preoperative period.

METHODS
Enrollment: US patients with recurrent or progressive grade 2/3 mIDH1 R132H glioma. Key eligibility: measurable enhancing disease, Karnofsky Performance Status ≥70, resectable (perioperative phase only). Following a March 2024 protocol amendment, inclusion criteria were expanded to include patients with oligodendroglioma in addition to patients with astrocytoma. Safety lead-in dosing: Cohort 1, VOR 40mg QD+pembrolizumab 200mg Q3W in 21-day cycles. The perioperative phase is randomized 1:1:1 to preoperative combination, VOR 40mg QD, or untreated for 28 (+7) days; all patients could opt to receive the VOR RCD in combination with pembrolizumab 200mg Q3W postoperatively. Primary objectives: safety and tolerability of VOR RCD administered with pembrolizumab; CD3+ T-cell infiltration in resected tumors following presurgical treatment with combination compared to untreated tumors.

RESULTS
Seven patients with recurrent or progressive enhancing grade 2/3 astrocytoma with an mIDH1 R132H were dosed in the safety lead-in phase. No dose-limiting toxicities were detected during this phase.

CONCLUSION
VOR 40mg QD+pembrolizumab 200mg Q3W was confirmed as the RCD for the perioperative phase. This phase was opened to enrollment in May 2023, and recruitment is ongoing.