INTRODUCTION:Glioblastoma is the most common and lethal adult primary brain cancer, and its incidence is predicted to increase among older patients. Elderly age has been associated with worse outcomes compared to younger patients with glioblastoma. It is unknown if very elderly patients are at even further increased risk of worse outcomes compared to elderly patients. METHODS:Patients ≥ 65 years old with primary glioblastoma treated surgically at a single institution (6/1/2008-12/31/2020) were identified through chart review. Patient demographics, disease characteristics, management data, and clinical outcomes were collected. Kaplan-Meier curves were generated to study overall survival. Chi square, independent t, and Wilcoxon-Mann-Whitney tests were used to identify associations between variables, and factors that affected clinical outcomes were identified using a multivariate logarithmic regression model. P-values < 0.05 were considered significant. RESULTS:A total of 165 elderly (65-74 years) and 79 very elderly (≥ 75 years) patients were included. Compared to elderly patients, very elderly patients were more likely to have a higher mFI-5 score (elderly 0.8 ± 0.9; very elderly 1.2 ± 0.9; p = 0.0018) and lower KPS score (elderly 73.6 ± 16.3; very elderly 69.1 ± 16.3; p = 0.0439) pre-operatively. Very elderly patients were less likely to receive post-operative adjuvant radiotherapy (elderly 70.4 %; very elderly 56.6 %; p = 0.0359) or adjuvant temozolomide chemotherapy (elderly 37.2 %; very elderly 21.3 %; p = 0.0165). In multivariate analysis, age ≥ 75 years was an independent predictor of extended ICU (OR 4.71, p = 0.0045) and overall length of stay (OR 2.03, p = 0.0374) compared to elderly patients. Adjuvant chemoradiation was associated with increased median overall survival in both the elderly (p < 0.0001) and very elderly (p < 0.0001). CONCLUSION:Very elderly patients with glioblastoma may be less likely to receive adjuvant chemoradiation than elderly counterparts, but use of these modalities is associated with increased overall survival in both cohorts.

Abstract Introduction As oncologic care continues to evolve with the advent of targeted therapies, survival of patients with metastatic spine disease (MSD) has also continued to improve. Thus, it is of an utmost priority for spine surgeons treating patients with MSD to understand the landscape of molecular subtypes and associated therapies. We sought to review the literature on this topic and develop a high-yield review for the treating spine surgeon. Methods A review of the literature was performed using PubMed, Google Scholar, and Medline databases. Histology-specific guidelines from the National Comprehensive Cancer Network (NCCN) were also reviewed. Articles that discussed the treatment of MSD patients with described molecular mutations with targeted therapies, as well as clinical outcomes, were included. Results The authors provide a framework for actionable mutations of malignancies commonly leading to MSD. Hormone receptor (HR) mutations as well as human epidermal growth factor receptor (HER2) mutations in primary breast cancer tumors confer a survival advantage as opposed to patients with triple negative breast cancer. Notably, a small number of patients with HR responsive breast cancer develop resistance to endocrine therapies in the setting of metastatic disease, and thus cannot receive targeted treatment following surgery. While prostate cancer is often initially hormone responsive, eventually tumors develop resistance, and few targeted therapies are limited. BRAF-targeted mutations for treatment of metastatic melanoma confer survival benefit when compared to chemotherapy alone. As with all systemic therapies, these medications all confer risk for patients undergoing surgical intervention, especially with regard to wound healing and bleeding. Conclusion While a vast range of targeted therapies exist, we present a review relevant to those treating patients with MSD. Many patients with MSD have a tumor histology with an actionable mutation, thus preserving neurologic function in these patients is of high priority but not without risk.

BACKGROUND CONTEXT:It is currently unknown what absolute change in Spine Oncology Study Group Outcomes Questionnaire (SOSGOQ2.0) represents a clinically meaningful change for a patient which causes challenges with the interpretation of the SOSGOQ2.0 total score or domain scores. PURPOSE:The aim of this study was to determine the minimally clinically important difference (MCID) for the SOSGOQ2.0 in patients with spinal metastases. STUDY DESIGN:An international multicenter prospective observational study by the AO Spine Knowledge Forum Tumor. PATIENT SAMPLE:Patients with spinal metastases who were treated with surgery and/or radiotherapy OUTCOME MEASURES: Health related quality of life (HRQOL) was evaluated using the SOSGOQ2.0 at predefined time points METHODS: The MCID values for the SOSGOQ2.0 were determined using both distribution-based as well as anchor-based methods. For the anchor-based method, the posttherapy questions of the SOSGOQ2.0 served as the anchor with response options collapsed into "improvement," "no change" and "deterioration." Spearman correlation coefficients were calculated to identify posttherapy items with a correlation of ≥0.30 with the corresponding domain scores. MCID values from the distribution-based methods were derived using the statistical characteristics of the study population and compared to the anchor-based results. RESULTS:A total of 317 patients had SOSGOQ2.0 data available at baseline and at 12 weeks posttreatment and were included in the final analyses. Anchor-based MCID values for improvement in the physical function, pain, mental health and social function domains were 10.2, 26.0, 14.4 and 17.2 respectively. Compared with the distribution-based approach, anchor-based MCIDs for improvement suggest that the patient-perceived improvement corresponds to a strong level of improvement. CONCLUSIONS:This is the first study to report MCID values for the SOSGOQ2.0 total score and domain scores. The distribution-based MCID estimates will help both clinicians as well as researchers with the interpretation of the effect of treatment for painful spinal metastases on patient reported health related quality of life (HRQOL). TRIAL REGISTRATION:Clinical trials identifier NCT01825161.

Abstract Background Glioblastomas are characterized by the Warburg effect, driven by upregulation of pyruvate dehydrogenase kinase (PDK), which inhibits pyruvate dehydrogenase complex (PDC), leading to lactate accumulation. Dichloroacetate (DCA) is a potent and safe PDK inhibitor that crosses the blood-brain barrier, reverses Warburg metabolism, and reduces lactate levels. Methods This trial (RO1FD007271) evaluated the pharmacodynamics and pharmacokinetics of oral DCA in recurrent glioblastoma patients requiring surgical debulking. The primary endpoint was decreased PDC phosphorylation (p-PDHA1) in resected tumors. Patients received either one week of DCA or no DCA prior to surgery. All patients received DCA post-operatively. Enhancing and non-enhancing tumor tissue, and serial plasma DCA and lactate levels were analyzed. Results 37 patients were enrolled (median age=60 years). In DCA-treated patients, the contrast-enhancing tumor had lower p-PDHA1, PDK4, HIF1-α, VEGF-α, and PGK1 expression (all p < 0.05) than non-DCA treated patients. In non-enhancing tumors, p-PDHA1 and PDK 1-3 expression were not different, but PDK4, PCNA and PGK1 levels were reduced, and ERK1/2 was increased in DCA-treated patients (all p ≤ 0.01). At surgery, DCA-treated patients had lower plasma lactate (p = 0.004) than untreated patients. Post-operatively when all patients received DCA, plasma lactate fell dramatically (p < 0.001). DCA was well-tolerated but did not delay tumor recurrence. Conclusions In recurrent glioblastomas, DCA was safe, well-tolerated, and promoted aerobic respiration. It reduced markers of tumor cell proliferation and lowered plasma lactate. Although no clinical benefit was noted, further studies of combination therapy are indicated, given the known association between poor cancer outcomes and elevated PDK expression and lactate levels.

BACKGROUND/OBJECTIVES:The latest National Comprehensive Cancer Network (NCCN) Central Nervous System (CNS) Guidelines recommend utilizing next-generation sequencing (NGS) to enable comprehensive genomic profiling (CGP) as the preferred approach for molecular characterization of central nervous system (CNS) malignancies. CNS malignancies present distinct challenges due to the infeasibility of tissue-based testing for many patients and the restrictive nature of the blood-brain barrier (BBB) making plasma-based liquid biopsy an ineffective alternative. Recent advances in liquid biopsy have extended molecular testing beyond plasma to include cerebrospinal fluid (CSF), which serves as a valuable source for tumor-derived nucleic acids. METHODS:The Belay Summit™ 2.0 is a high-throughput CGP assay capable of detecting multiple variant types, including single nucleotide variants (SNVs) and small insertion and deletions (Indels), copy number variations (CNVs), gene fusions, splice variants, and immunotherapy biomarkers such as microsatellite instability (MSI) and tumor mutational burden (TMB). This study details the analytical and clinical validation of Summit™ 2.0 to assess its technical performance and clinical sensitivity. Analytical validation was conducted using 68 specimens, demonstrating robust and reproducible detection of all variant types with 15 ng of CSF-derived total nucleic acid (tNA). RESULTS:The analytical sensitivity of the Belay Summit™ 2.0 assay for SNVs and Indels was determined to be 96.7% with a 100% limit of detection (LoD) at a variant allele frequency of 0.3%. Clinical validity was evaluated across a cohort of 118 CSF specimens, including both primary and metastatic CNS tumors, demonstrating 96% sensitivity and 98% specificity. CONCLUSIONS:These findings support the use of the Belay Summit™ 2.0 assay for accurate and reproducible genomic profiling of CNS tumors using tumor-derived nucleic acids from CSF in patients for whom tissue-based testing is considered infeasible, unsafe, or not deemed by the prescribing physician to be clinically appropriate.

Study Design Narrative Review. Objectives To summarize the scientific contributions generated from the AO Spine Knowledge Forum Tumor (AOSKFT) databases, focusing on primary spine tumors, and highlight key findings, research trends, and future directions. Methods Data from the Primary Tumor Retrospective (PT-Retro) and Primary Tumor Research Outcome Network (PTRON) registries were analyzed. The nineteen studies included were peer-reviewed manuscripts focused on primary spine tumors, excluding abstracts, book chapters, systematic reviews, and metastatic studies. Results The PT-Retro registry compiled data from 1495 patients across 18 primary tumor histologies, offering insights into recurrence, survival, and treatment paradigms. Key findings emphasize the importance of Enneking-appropriate (EA) resection in improving survival and reducing recurrence in tumors such as chordoma, chondrosarcoma, and osteosarcoma. Genetic markers, including hTERT promoter mutations and rs2305089 SNP, were linked to prognosis in specific histologies. Benign tumors, such as giant cell tumors and aneurysmal bone cysts, demonstrated variable outcomes with different surgical approaches and selective arterial embolization. Conclusions The AOSKFT registries have significantly advanced knowledge in primary spine tumor management, emphasizing preoperative staging, surgical margins, and multidisciplinary approaches. International, multicentric registries are essential for studying rare diseases like primary spine tumors, enabling robust data collection, improved statistical power, and broader applicability of findings across diverse clinical settings. Ongoing prospective data collection through PTRON will further refine evidence-based care for these rare and challenging conditions.

Abstract Background: Machine learning-generated segmentations of the trigeminal nerve and nearby blood vessels have the potential to quantify the magnitude of neurovascular compression (NVC) in patients with trigeminal neuralgia (TN). This study applies the nnU-Net machine learning method to create segmentations of the trigeminal nerve region from patient MRIs and correlate resulting quantitative NVC metrics with postoperative TN outcomes. Methods: MRIs from patients undergoing microvascular decompression (MVD) for TN from 2019 to 2022 at a single tertiary care facility were split into training, testing, and inference datasets. The trigeminal nerve and surrounding vasculature were manually labeled (i.e., segmented) in the training and testing datasets to create ground truth (GT) segmentations. nnU-Net was trained on GT segmentations in the training dataset, and predicted segmentations were evaluated using the testing dataset via the F1 score, IoU score, and paired comparison of resulting metrics. To contextualize nnU-Net performance, a manual SE-ResNet152 model was trained and deployed using the same datasets. Predicted nnU-Net segmentations in the inference dataset were then correlated with the rate of post-MVD pain recurrence. Results: Of 366 total GT segmentations, 302 (82.5%) trained the nnU-Net model and 64 (17.5%) validated the predicted segmentations. The nnU-Net model's F1 and IoU scores on the testing dataset were 0.797+/-0.011 and 0.714+/-0.011, respectively, which were higher than those for SE-ResNet152. The sensitivity and specificity of nnU-Net's ability to detect NVC were 91.3% and 66.7%, respectively. Surface area of NVC calculated from nnU-Net and GT segmentations were statistically similar. Deployed on the inference dataset (n=100), higher surface area of NVC was observed in patients without pain recurrence following MVD than patients with pain recurrence (p=0.008). Finally, higher surface area of NVC (hazards ratio [HR] 0.914 per mm2, 95% confidence interval [CI] 0.848-0.985, p=0.019) and presence of NVC (HR 0.369 relative to absent NVC, 95% CI 0.156-0.876, p=0.024) were both associated with a significantly decreased risk of pain recurrence in Cox proportional hazards models. Conclusion: nnU-Net can generate high-fidelity segmentations of the trigeminal nerve region, and the resulting NVC surface area metric is significantly associated with post-MVD pain recurrence. nnU-Net can be a standardized tool to evaluate NVC severity for patients seeking TN treatment. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Approval granted by the Johns Hopkins Medicine Institutional Review Boards. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.

e14042 Background: Metastatic cancers to the central nervous system (CNS) usually affect the brain. A small but clinically significant proportion also develop intradural spinal disease, though little is known about lesions to this compartment. Here, we characterize the molecular features of intradural spinal disease that spread from non-CNS cancers and describe the metastatic chronology such lesions go through to reach this space. Methods: All patients with MRI spine report findings of intramedullary or leptomeningeal lesions from 2020–2025 at a tertiary academic center were screened for intradural spinal disease. Patients with primary CNS cancer or non-cancer diagnoses were excluded. Demographic information, CSF cytopathology results, imaging characteristics of intradural spinal disease, dates of primary cancer and metastasis detection (CNS and non-CNS sites), and immunohistochemistry and next generation sequencing data of all disease sites were collected wherever available. The primary outcome of interest was overall survival (OS) from date of primary diagnosis. Results: 1401 patients were screened and 69 met inclusion criteria. The most common primary pathologies were lung (23/69, 33.3%) and breast (22/69, 31.9%). 30 (43.5%) patients had lumbar punctures for CSF cytopathology, of which 16 (23.2%) detected tumor cells. 8/69 (11.6%) patients underwent surgery for intradural disease. The distribution of intradural spine disease on initial detection was 38 (55.1%) cervical, 45 (65.2%) thoracic, and 53 (76.8%) lumbar. The mortality rate was 87.0% (60/69) within a median follow-up of 20.6 (IQR 42.0-72.9) months after primary cancer diagnosis. The median time from primary diagnosis to any metastasis was 0.5 (0-6.7), to the brain was 14.9 (0.6-42.7), to the osseous spine was 19.4 (0.7-38.9), and to the intradural spine was 29.5 (14.0-52.6) months. Mutations with common targetable therapeutics were noted in 32/69 (46.4%) primary lesions and patients with such actionable mutations trended towards improved OS (51.7 months, 31.2-105.2) compared to patients without (30.1 months, 12.6-58.9, p=0.072). The molecular profile of the intradural spine lesions were notably different from systemic markers for actionable mutations in 2/8 (25%) cases. Conclusions: Actionable mutations are present in nearly 50% of patients who develop spinal intradural disease, and so regular molecular characterization and sequencing of this space (e.g. CSF liquid biopsy) could have a clinically meaningful impact on these patients. Further, surveillance imaging of patients concerning for spinal intradural disease can miss >25% of intradural spinal disease if MRI of only one part of the spine is regularly imaged.

Background Chordomas are locally aggressive notochordal tumors with no systemic therapy options. As an ultra-rare cancer type, our understanding of its immune landscape is limited. While tumor-associated macrophages (TAMs) and T cells are critical components of the immune landscape, their functional states and interactions remain poorly understood.Methods We conducted an integrative analysis of 35 chordoma samples and six paired tumor-PBMC samples using single-cell RNA sequencing (scRNA-seq), T-cell receptor (TCR) profiling, and multiplex immunofluorescence. Immune cell phenotypes, spatial distribution, TCR motif diversity, and functional states were assessed using unbiased co-expression network analysis and predictive modeling.Results Chordomas exhibited remarkable immune cell heterogeneity, ranging from highly infiltrated to immune-desert tumors. Tumor-associated macrophages dominated the tumor microenvironment (TME) and were enriched for antigen-processing pathways. T-cell receptor profiling revealed clonal overlap between tumor-infiltrating and peripheral T cells, suggesting systemic anti-tumor responses. Exhausted CD8+ T cells exhibited restricted clonality and tumor-specific amino acid motifs. Weighted gene co-expression network analysis (WGCNA) identified gene modules associated with immune activation and suppression, underscoring the dual roles of immune cells in the TME. Spatial analysis revealed fibrous septa as immune interaction hubs, where immune cell clustering was significantly higher than in tumor regions.Conclusions This study advances understanding of the chordoma immune landscape by integrating spatial, transcriptomic, and TCR data. The findings highlight systemic and local immune dynamics, reveal tumor-specific TCR motifs, and identify potential therapeutic targets. These insights provide a foundation for developing personalized immunotherapies to overcome immune suppression and enhance anti-tumor immunity in chordomas.

Intramedullary spinal cord tumors (IMSCTs) pose a high risk of iatrogenic neurologic injury during resection, yet no blood-based assay is available to quantify intra-operative neuroglial damage in real time. A 36-year-old woman with a C7–T3 WHO grade II ependymoma underwent laminoplasty and microsurgical gross total resection. Peripheral blood was collected at five peri-operative time points. Spinal cord-derived cell free DNA was quantified by droplet-digital PCR, and 119-plex proteomics measured four previously validated proteins (FABP-3, REST, IL-6, NF-H). The Spinal Cord Injury Index (SCII)—a dimensionless composite generated from these analytes—was calculated at each time point. SCII increased after initial myelotomy, peaking at myelotomy completion, then returned to pre-myelotomy levels by postoperative day 1. In contrast, glial fibrillary acidic protein and neurofilament-light concentrations were lagging indicators that continued increasing after completion of myelotomy and into postoperative day 1. SCII demonstrated temporal fidelity to the patient’s neurologic trajectory and outcome. SCII may allow for high temporal fidelity, molecular monitoring that parallels surgical manipulation and precedes classical protein biomarker elevations, suggesting potential future utility as a real-time liquid biopsy for spinal-cord monitoring during neurosurgical oncology.

This cross-sectional study characterizes the care pathways of US patients with trigeminal neuralgia from the onset of their pain until their first neurosurgical consultation in terms of symptom duration.

Abstract Metastatic cancers to the central nervous system (CNS) usually affect the brain, but a small and clinically significant portion also affect the intradural spinal space. Here, we characterize the molecular features of metastatic intradural spinal disease and describe the metastatic chronology such lesions go through to reach this space. All patients with MRI spine findings of intramedullary or leptomeningeal lesions from 2020–2025 at a tertiary academic center were screened. Patients with primary CNS cancer or non-cancer diagnoses were excluded. Demographic information, imaging findings, dates of primary cancer and metastasis detection, and molecular data across disease sites were collected. The primary outcome of interest was overall survival (OS) after primary diagnosis. 69 patients met inclusion criteria out of 1401 patients screened. The most common primary pathologies were lung (33.3%) and breast (31.9%). 11.6% of patients underwent surgery for intradural disease. The distribution of intradural spine disease on initial detection was 55.1% cervical, 65.2% thoracic, and 76.8% lumbar. The mortality rate was 87.0% within a median follow-up of 20.6 (IQR 42.0-72.9) months. The median time to any metastasis was 0.5 (0-6.7), to the brain was 14.9 (0.6-42.7), to the osseous spine was 19.4 (0.7-38.9), and to the intradural spine was 29.5 (14.0-52.6) months. Targetable mutations were noted in 46.4% of primary lesions and such patients trended towards improved OS (51.7 months, 31.2-105.2) compared to patients without (30.1 months, 12.6-58.9, p = 0.072). Actionable mutations are present in nearly 50% of patients who develop spinal intradural disease, and so regular molecular characterization and sequencing of this space (e.g. CSF liquid biopsy) could have a clinically meaningful impact on these patients. Further, surveillance imaging of patients concerning for spinal intradural disease can miss >25% of intradural spinal disease if MRI of only one part of the spine is regularly imaged.

Mutation-associated neoantigens (MANAs) are highly cancer-specific targets for immunotherapy where peptides derived from intracellular mutant proteins are presented on the cell surface via HLA molecules. T cell-engaging bispecific antibodies and CAR T cells can target MANAs to eliminate cancer cells via T cell activation. However, the low antigen density of MANAs on the cell surface can limit therapeutic efficacy. Here, we investigated whether increasing the affinity of the H2 single-chain variable fragment (scFv) targeting the p53 R175H MANA (HMTEVVRHC presented on HLA-A*02:01) improves its therapeutic effect. We identified higher-affinity H2 variants via phage biopanning and a thiocyanate elution method. Increasing bispecific antibody affinity to the low nanomolar range increased cancer cell killing and tumor control in mouse xenograft models without sacrificing antigen specificity. We next asked how increasing scFv affinity impacts CAR T cell function - a matter of debate. We appended each variant scFv to a CD28z CAR, CD3γ, or the T cell receptor. In striking contrast to the bispecific antibody results, increasing CAR affinity decreased function in each CAR format due to lower T cell activation upon interaction with target cancer cells. These results have important implications for the design of future immunotherapeutic approaches targeting low-density antigens.

Purpose:National Comprehensive Cancer Network (NCCN) Central Nervous System (CNS) Guidelines recommend utilizing next-generation sequencing (NGS) to enable comprehensive genomic profiling (CGP) as standard of care for molecular characterization of CNS malignancies. The restrictive nature of the blood-brain barrier (BBB) makes plasma-based liquid biopsy an ineffective alternative, however cerebrospinal fluid (CSF)-based liquid biopsy offers a minimally invasive alternative for genomic assessment. This study aimed to evaluate the clinician perspective of clinical utility of Belay's CSF-based genomic assay, Summit™ 2.0, and to assess how clinicians use test results in routine clinical practice. Methods:Clinical utility was assessed using clinician-reported survey responses from cases where Summit™ 2.0 testing was ordered for patients with known or suspected CNS disease. Survey questions evaluated indications for testing, test positivity, impact on clinical decision-making, report clarity, and perceived overall utility. Results:The survey response rate was 52% (95 surveys sent). Among 49 surveyed cases, 74% yielded positive genomic findings. Clinicians most frequently ordered testing to address diagnostic uncertainty or inform clinical management, with treatment selection as a less frequent primary indication. Clinical utility was reported in 86% of cases including those with negative findings, of which some results were useful for confirming existing diagnoses or management strategies. Clinicians also reported high confidence in the clarity and usability of test reports. Conclusion:Clinician-reported outcomes indicate that Summit™ 2.0 CSF-based genomic testing influenced clinical decision-making, including treatment selection, diagnostic clarification, confirmation of expected diagnoses, and care planning and provides meaningful information that supports diagnostic evaluation and management of CNS tumors.

Abstract Introduction Given the palliative nature of treatment for metastatic spine disease (MSD), measuring surgical outcomes in this population requires examining comprehensive outcome variables. We sought to achieve an international consensus in how to measure success in the MSD population. Methods The AO Spine Knowledge Forum Tumor, consisting of dedicated spine oncology specialists, participated in a modified Delphi process between March 2023 and November 2024. The two part study asked which outcome variables were important to include in a composite outcome as well as what metrics would define a successful outcome. Results A total of 42 spine oncology surgeons and oncologists across North America, Latin America, Europe, and Asia participated. Over 90% of participants agreed or strongly agreed that composite measures should be used to assess the quality of surgical care when treating patients with MSD. Three outcome variables were selected to define a successful outcome as defined by the OSCO-M: the absence of a Spinal Adverse Events Severity System, Version 2 grade 3 adverse events or higher, maintaining or improving ECOG performance status at 90 days, and being ambulatory at 90 days. Conclusion This is the first study defining a composite measure outcome in oncologic surgery for spinal metastases derived from an international group of surgeons and oncologists who treat patients for MSD. The OSCO-M will be useful for defining clinical success in patients undergoing treatment for MSD.

Lethal toxins could become potent therapies against cancer, but their clinical utility is limited by adverse events upon systemic administration. These could be reduced if the toxins were delivered by effector cells that specifically infiltrate cancers, thereby releasing toxins locally into the tumor microenvironment. One of the challenges underlying this strategy is that cells delivering toxins would have to be resistant to them. We address this obstacle by showing that effectors derived from transformed human cell lines genetically engineered for resistance to bacterial adenosine diphos-phate ribosylating toxins (ADPRTs), including Pseudomonas aeruginosa exotoxin A (PE), can produce targeted immunotoxins that specifically kill cancer cells express-ing cognate tumor-associated antigens. Resistance to immunotoxins was achieved by knockout of genes in the diphthamide biosynthesis pathway (DPH1-4) required for the posttranslational modification of eukaryotic elongation factor 2 (EEF2) that is the target of ADPRTs or by mutation of EEF2 itself. We show that engineering resist-ance to ADPRTs, one of the most potent toxins acting on human cells, is essential to achieve robust function of armored effector cell lines. This work establishes a critical step on the path to equip effector cells with the ability to deliver powerful toxins to cancer cells and introduces a platform to investigate extension to primary autologous or allogeneic therapeutic cell types.

TPS2100 Background: BRAF V600E mutant gliomas are difficult to treat in the recurrent setting due to adaptive resistance to FDA-approved targeted therapies. Emerging therapeutic approaches include novel BRAF inhibitors or combination therapies, but evaluating treatment response is limited by radiographic techniques and the infeasibility of serial tissue sampling. This two-arm study will evaluate the feasibility of using CSF and plasma circulating tumor DNA (ctDNA) as biomarkers for response to a novel-BRAF inhibitor, plixorafenib alone or in combination with PD-1 inhibitor, retifanlimab. Plixorafenib is a small-molecule selective inhibitor of BRAF-V600E and BRAF-fusion alterations without inducing paradoxical reactivation of MAPK signaling. Methods: This single institution trial of plixorafenib alone (Arm A) or combined with retifanlimab (Arm B) is enrolling patients (18+ years of age) with BRAF-V600E mutant glioma following progression on prior BRAF-targeted therapy who are recommended for a clinically-indicated diagnostic or debulking surgery. Eligible patients have recurrent BRAF-V600E mutant glioma (any grade) with measurable disease (by RANO 2.0), and a Karnofsky performance status ≥ 70. Leptomeningeal disease is allowed. All enrolled patients will undergo clinically-indicated resection or biopsy for confirmation of disease progression and characterization of putative resistance alterations with a ventricular reservoir placed at time of surgery for CSF sampling. In both arms, patients will initiate oral plixorafenib once clinically recovered from surgery. Patients will take the plixorafenib daily with food. In Arm B, enrolled patients will receive one dose of retifanlimab three weeks prior to surgery, then resume monthly retifanlimab infusions after surgery in combination with oral plixorafenib. MRI, CSF, and plasma assessments will occur approximately every two months to evaluate disease status. The primary trial endpoint is detectable ctDNA at baseline and after one month of treatment with plixorafenib. Secondary endpoints include safety of plixorafenib alone or in combination with retifanlimab, response rate in each arm, and the correlation of ctDNA with disease status over time. The trial is IRB approved and enrollment is ongoing (10 patients per arm). Clinical trial identifier NCT06610682. Clinical trial information: NCT06610682 .

Purpose Spinal ependymomas are rare glial neoplasms. Given the rarity there is a lack of consensus on the use of radiation in these patients. This study aims to investigate the role of adjuvant radiation and identify predictors of functional outcome at last follow-up in patients with histology-confirmed intramedullary ependymomas. Methods We conducted a retrospective cohort study at a single center with 101 patients with histologically confirmed grade 2 spine ependymoma. We aimed to identify which patients benefit most from postoperative radiotherapy by analyzing preoperative features and outcomes in adjuvant RT recipients, and to assess functional outcomes at last follow-up. Patients with subependymomas, conus/filum terminale tumors, or drop metastases were excluded. KNN (K-Nearest Neighbors) matching based on age and sex was used to match patients. Results A total of 101 patients were included in this study, with a mean age of 43.2 years. The cervical spine was the most common location of the tumor (68.3