Abstract BACKGROUND Bevacizumab is an anti-angiogenic monoclonal antibody that inhibits vascular endothelial growth factor (VEGF) used in the treatment of various cancers including recurrent glioblastoma (rGBM) and is particularly useful in mitigating cerebral edema and radiation necrosis. Complications associated with bevacizumab that are of concern for patients requiring urgent surgical procedures include: impaired wound healing, increased bleeding risk and infection. Recent bevacizumab use (e.g. <28 days) is considered a contraindication to surgical procedures. Therapeutic plasma exchange (TPE) is a procedure that nonspecifically removes substances from plasma such as immunoglobulins. We reviewed our institutional experience with the use of TPE to remove bevacizumab for patients who required urgent neurosurgical intervention. METHODS Single center retrospective study from: 01/01/2022 to 12/31/2024 (first patient treated for this indication was in 2022). Inclusion criteria: patients who underwent perioperatively TPE to remove bevacizumab. Data collected from electronic medical record included age, gender, pertinent medical history, indication for bevacizumab and TPE for its removal, TPE procedure parameters, and clinical outcomes. RESULTS Four patients met study inclusion criteria, all were male. Three patients had a diagnosis of rGBM, one patient had a diagnosis of metastatic melanoma. All patients had received bevacizumab within 21 days of TPE (range 8-21). All subjects underwent 3 daily, 1 plasma volume TPE. Eleven of 12 procedures used the Fenwal Amicus® Separator. Neurosurgical outcomes were favorable. In one patient, bevacizumab levels measured by ELISA decreased from 1087.63 ng/mL to 145.35 ng/mL after the third procedure. No post-surgical wound complications (e.g., wound dehiscence, bleeding, infection) were observed in four patients requiring urgent neurosurgery despite recent administration of bevacizumab. CONCLUSIONS TPE was successful and well-tolerated by subjects in this study. Perioperative bevacizumab removal by TPE may be considered to reduce the risk of wound healing complications associated with bevacizumab.
BIOM-78. DNA-METHYLATION PROFILING OF PAN-CANCER BRAIN METASTASES REVEALS EPIGENETIC SIGNATURE ASSOCIATED WITH IMPROVED PATIENT OUTCOMES
Abstract Brain metastases (BMs) are a common and often fatal progression of systemic cancers, affecting up to 25% of patients. Despite advances in surgical resection and radiotherapy, the median survival remains limited to 10–16 months. While genomic profiling has enabled the development of targeted therapies, there remains a paucity of prognostic tools for clinical use. To address this, we explored the utility of DNA methylation profiling—an epigenetic marker increasingly recognized for its diagnostic and prognostic value. We profiled fresh-frozen tissue from 327 surgically resected BM samples of lung, breast, melanoma, and gastrointestinal (GI) origin using the Illumina Infinium MethylationEPIC BeadChip array. Unsupervised analysis via partitioning around medoids (PAM) clustering identified five robust groups. Four of these correlated closely with primary tumor origin. However, a distinct “Poly-Origin Cluster” emerged, comprising tumors from multiple primary sites with a shared epigenetic signature. Poly-Origin tumors showed improved survival outcomes compared to origin-aligned clusters (20.2 vs. 10.1 months, p=0.0018), independent of clinical covariates. Notably, these tumors were enriched for immune cell infiltration—including CD14+ macrophages, CD19+ B-cells, and CD56+ NK cells—based on deconvolution analysis, and exhibited reduced genomic instability as measured by copy number variation. These tumors were enriched for pathways related to cell signaling. We validated the prognostic significance of the Poly-Origin methylation signature in a publicly available independent cohort (n=96), and found that high signature concordance correlated with extended survival. Finally, we demonstrated the feasibility of detecting this signature in plasma-derived cell-free DNA using cfMeDIP-seq, with high classification accuracy (AUC = 0.98). These findings reveal a clinically meaningful subtypes of BM not captured by tissue origin or mutation status alone. Our work suggests that DNA methylation profiling may be a powerful tissue- and liquid biopsy–based tool that holds promise as a non-invasive prognostic biomarker in the management of brain metastasis.
STEM-24. SINGLE CELL CRISPR/CAS-9 LINEAGE TRACING REVEALS EVOLUTIONARY FITNESS, EXPANSION AND PLASTICITY AXES IN ADULT DIFFUSE GLIOMAS
Abstract A major barrier in understanding adult diffuse gliomas lies in the inability to track tumor evolution in real time. To address this, we employed a novel method known as continuous lineage tracing, which integrates CRISPR/Cas9-based expressed DNA barcoding with single-cell RNA sequencing, enabling a phylogenetic approach to studying tumor development. Patient-derived glioma-initiating cell lines were engineered with expressed barcodes targeted by CRISPR/Cas9 and implanted into mice to create intracranial xenografts. Tumors underwent single-cell RNA sequencing; expressed barcodes were used to infer clonal relationships, and transcriptomic profiles enabled cell state classification. Phylogenetic lineage trees were reconstructed using lineage inference algorithms to characterize cell fitness, expansion, and plasticity. Our analysis uncovered extensive intra-clonal cell state heterogeneity, indicating active phenotype switching prior to therapy. We identified consistent transcriptional programs associated with tumor engraftment and in vivo clonal advantage. Lineage tracing revealed gene expression signatures linked to key phenotypes: fitness, enriched for neural-mesenchymal and injury-response pathways; expansion, associated with RNA splicing; and plasticity, correlated with cell cycle and DNA repair programs. Glioma stem cells appeared to span a transcriptional continuum from undifferentiated, high-fitness states to more differentiated, low-fitness states, with high-fitness cells potentially representing transitional phenotypes. We then validated these findings in a cohort of 185 surgically resected gliomas with matched bulk RNA and proteomic data. Phylogenetic gene signatures differed markedly between IDH-mutant and IDH-wildtype tumors. When stratified by tumor type, both fitness and expansion signatures were significantly associated with overall survival in GBM (median 12.6 months, p=0.041) and oligodendrogliomas (median 66 months, p=0.027). This study demonstrates the utility of continuous lineage tracing to reconstruct tumor evolution and identify transcriptional programs linked to tumor growth and prognosis. Our approach provides a powerful framework for dissecting glioma biology and identifying potential therapeutic vulnerabilities.
BIOM-31. PLASMA CELL-FREE DNA METHYLOME PREDICTS RESPONSE TO COMBINED PARP AND IMMUNE CHECKPOINT INHIBITION IN IDH-MUTANT GLIOMA
Abstract INTRODUCTION Recurrent IDH-mutant gliomas pose a significant therapeutic challenge, with limited treatment options following progression after standard therapy. Combining PARP inhibitors with immune checkpoint blockade has been proposed as a synergistic strategy in IDH-mutant high-grade gliomas, leveraging vulnerabilities in homologous recombination repair and increased PD-L1 expression following PARP inhibition. OBJECTIVE This phase II trial (NCT03991832) evaluated the combination of the PARP inhibitor olaparib and the PD-L1 inhibitor durvalumab in patients with recurrent IDH-mutant glioma. We also investigated the potential of the plasma tumor methylome as a non-invasive biomarker of treatment response. METHODS Twenty-nine patients (median age 40.5 years; 41% female) were enrolled between January 2020 and February 2023. All patients received olaparib (300 mg twice daily) and durvalumab (1,500 mg IV every four weeks) until radiographic or clinical progression. Plasma samples were collected at baseline and monthly, and cell-free methylated DNA immunoprecipitation sequencing (cfMeDIP-seq) was performed. RESULTS The objective response rate was 10%, and median overall survival was 9.3 months. Longitudinal cfMeDIP-seq profiling enabled development of a circulating methylome classifier that accurately distinguished responders from non-responders. Integration with matched tumor transcriptomic and methylation data revealed enrichment of immune and DNA repair pathways in responders. Whole-exome sequencing identified no consistent mutational correlates. Spatial transcriptomic analysis demonstrated a more interactive, immune-rich tumor microenvironment and reduced malignant cell state diversity in responders. CONCLUSION This study supports the safety of combined PARP and PD-L1 blockade in recurrent IDH-mutant glioma and highlights the plasma methylome as a promising non-invasive biomarker of therapeutic response.
BIOM-66. MODERN MOLECULAR PROFILING RECONTEXTUALIZES THE RTOG-0539 TRIAL AND REVEALS HIDDEN HIGH-RISK AND RADIOTHERAPY RESISTANT MENINGIOMAS
Abstract Meningiomas are the most common primary intracranial tumors and exhibit clinical heterogeneity. Radiotherapy (RT) remains the only adjuvant therapy, but response is variable and biomarkers are limited. RTOG-0539 is the first prospective phase 2 trial to stratify meningioma patients for adjuvant RT based on clinical risk. Here, we apply modern molecular tools to this cohort and uncover correlates of RT response. To do so, tumor tissue from 100 RTOG-0539 patients was profiled using DNA methylation arrays, RNA sequencing, and whole-exome sequencing. Recurrence scores, Molecular Groups, gene expression, and copy number alterations were compared across clinical groups and between RT responders and non-responders. Using this approach, modern grading criteria, including brain invasion, TERT mutation, CDKN2A/B deletion and 1p/1q status, would reclassify 10% of tumors and alter treatment group assignment in 7%. Notably, non-responders to RT had more frequent 1p and 14q loss, and greater copy number burden. In addition, transcriptomic and epigenetic profiling revealed immune-related signatures in RT responders and upregulation of cell cycle–related pathways in RT non-responders, several of which overlapped with targets of vorinostat, a histone deacetylase inhibitor validated in aggressive meningioma models. Of particular importance, the Proliferative Molecular Group was an independent predictor of post-RT recurrence in multivariable analysis, outperforming WHO grade. In conclusion, multi-omic analysis of the RTOG-0539 cohort shows that updated WHO grading criteria, incorporating molecular and cytogenetic features, improve risk stratification. However, molecular classification, particularly the Proliferative group, remains an independent and stronger predictor of RT response. These findings support integrating molecular biomarkers alongside modern grading frameworks to guide treatment and trial design in meningioma.
BIOM-113. TERT EXPRESSION IN MENINGIOMAS PREDICTS PROGRESSION-FREE SURVIVAL INDEPENDENT OF TERT PROMOTER MUTATION
Abstract INTRODUCTION While TERT promoter mutation (TPM) has been established as a marker of clinically aggressive meningiomas, this alteration is rare and found in less than 5% of all cases. However, a larger subset of meningiomas may exhibit aberrant TERT expression in the absence of TPMs. This study investigated the effect of TERT gene expression on clinical outcome in meningioma patients. METHODS Clinical and molecular data were retrospectively collected on 1241 meningiomas, split into a Toronto discovery cohort and a multi-institutional validation cohort. Sanger sequencing and bulk RNA sequencing were used to determine TPM status and TERT gene expression. The effect of TERT expression on progression-free survival (PFS) was assessed using Kaplan-Meier and Cox regression analysis. RESULTS While meningiomas with TPM showed expectedly higher TERT gene expression compared to wildtype (TP-WT) cases (p<0.0001), TERT expression was still detected in 28.7% (157/547) of TP-WT meningiomas. Meningiomas with TERT expression showed significantly worse PFS compared to meningiomas without any TERT expression. In fact, WHO grade 1 meningiomas with TERT expression had PFS outcomes resembling WHO grade 2 meningiomas lacking TERT expression (p=0.59). In turn, WHO grade 2 meningiomas with TERT expression had clinical outcomes similar to WHO grade 3 meningiomas without TERT expression (p=0.42). Furthermore, the proportion of meningiomas expressing TERT as well as overall TERT expression levels increased with increasing WHO grade. Multivariable analysis showed that TERT expression was significantly associated with worse PFS even when controlling for other known predictors of clinical outcome including TPM, CDKN2A/B loss, 1p/22q status and WHO grade (HR 1.85 [95% CI 1.33-2.57], p=0.00024). CONCLUSION TERT expression is a novel independent biomarker of outcome for meningiomas identifiable in up to one-third of cases that may be utilized to reclassify tumours to a higher WHO grade.
Assessment of molecular tools in pediatric, adolescent, and young adult meningioma highlights the need for lifespan precision in neuro-oncology
Abstract Background Adolescent and young adult (AYA) patients remain underrepresented in neuro-oncology research. Despite being the second most common primary brain tumor in this population, meningiomas have not been studied using age-specific molecular analyses. DNA methylation-based classification and prognostic tools have transformed meningioma care. This study aimed to evaluate the performance of these tools across age groups. Methods We analyzed 1,568 meningiomas with DNA methylation and clinical data, including 18 pediatric patients (<15 years), 195 AYA patients (15-39 years), and 1,355 adult patients (>39 years). Pediatric and AYA (P/AYA) tumors were combined and compared with adult tumors. The performance of established molecular classifiers and recurrence predictors, as well as differences in chromosomal copy number alterations were compared across age groups. Results While histologic grading was comparable between cohorts, P/AYA tumors displayed significantly fewer aggressive molecular groups and lower frequencies of chromosomal arm losses, including 1p, 6q, and 14q. The adult-trained recurrence predictor failed in the P/AYA population (AUC 0.57), despite similar score distributions. Retraining the model on an age-specific cohort using an identical analytic framework improved performance (AUC 0.79) and enabled effective stratification of progression-free survival (P = 0.00054). Importantly, 1p loss retained prognostic significance within the P/AYA group, supporting its clinical utility. Conclusions Molecular tools developed in adult-dominant cohorts do not generalize to younger patients due to both biological divergence and exclusion from model development. These findings underscore the need for age-specific molecular frameworks and highlight the imperative of including P/AYA populations in precision neuro-oncology research to ensure lifespan-equitable care.
Background: Sepsis survivors experience substantial long-term cardiovascular (CV) morbidity and mortality. The pooled-cohort atherosclerotic cardiovascular disease (ASCVD) score estimates 10-year risk in the general population, but its accuracy soon after sepsis is unknown. Objectives: (1) Describe the absolute five-year incidence of major adverse cardiovascular events (MACE) after sepsis hospitalization. (2) Evaluate the discrimination and calibration of the 10-year ASCVD score for predicting five-year MACE in this setting. Research Questions: The ASCVD score would underpredict five-year MACE in sepsis survivors, reflecting their heightened risk. Methods: We performed a retrospective closed-cohort study using electronic health records from Mayo Clinic hospitals (USA). Adults aged 40–75 years hospitalized for sepsis between 2018 and 2020 were eligible if follow-up was ≥5 years; the age criterion matched the derivation range of the ASCVD score. The primary outcome was five-year MACE—myocardial infarction (MI), ischemic or hemorrhagic stroke, or CV death. Secondly we evaluated the predictive performance of ASCVD score for five-year MACE. Discrimination was assessed with the area under the receiver-operating curve (AUROC); calibration with Calibration-in-the-Large (CITL, ideal = 0) and slope (ideal = 1). Performance metrics were calculated in patients with complete ASCVD variables. Results: A total of 6306 sepsis admissions were screened. 2424 patients were excluded for age outside 40–75 years and 879 for <5 year follow-up, leaving 2718 patients for incidence analyses. Median age was 65 years (IQR 56–70); 55 % were male, 38 % required ICU care, and 91 % were White. Median body-mass index was 28.2 kg/m2 (IQR 23.7-34.7). During follow-up, 125 patients (4.6 %) had MI, 219 (8.1 %) experienced stroke, and 303 (11.1 %) died of CV causes; overall, 1573 patients (57.9 %) met the composite MACE outcome. Complete ASCVD data were available for 409 patients. In this subset, discrimination was moderate (AUROC 0.65; 95 % CI 0.59–0.71). Calibration showed CITL +0.34 (95 % CI 0.09–0.59) and slope 0.50 (95 % CI 0.28–0.72), indicating systematic infra-prediction and over-fitting, respectively. Conclusion: Five-year MACE incidence after sepsis is high. The 10-year ASCVD score moderately discriminates but underestimates five-year CV risk in this population, highlighting the need for sepsis-specific predictive models or recalibration to guide targeted post-sepsis cardiovascular prevention.
Abstract Sun705: Comparison of 5-Year Neurologically Intact Survival Between an Automated Head Up CardiopulmonaryResuscitation Registry and a National Cardiac Arrest Registry
Background: Pre-clinical animal studies have demonstrated improved cerebral blood flow and neurological survival with Automated Head Up Position (AHUP) cardiopulmonary resuscitation (CPR) as compared to flat conventional (C) CPR. AHUP CPR consists of 1) automated head and thorax elevation 2) active compression decompression CPR and 3) an impedance threshold device. Subsequently, observational propensity-matched studies of out-of-hospital cardiac arrest (OHCA) patients demonstrated a time-dependent association between survival with intact neurological function (SNF) and application of AHUP CPR. However, comparison of AHUP CPR outcomes with contemporaneous C-CPR controls is lacking. Hypothesis: Use of AHUP CPR for OHCA by first responder agencies will demonstrate a higher incidence of SNF compared to C-CPR outcomes from a national registry Methods: Data from the previous 5 years (2020-2024) from an AHUP-CPR Registry comprised of OHCA patients routinely treated by first responders with AHUP CPR were compared with data from the Cardiac Arrest Registry to Enhance Survival (CARES). Patient demographics, arrest characteristics, ROSC, SHD, and SNF were recorded. SNF was defined as a Cerebral Performance Category 1 or 2 at hospital discharge. A two-sample test of proportions was used for outcome comparisons. Results: Nine AHUP registry sites (MN, FL, TN, IL, OK, VA, AL, IA, MI) were included. Summary 5-year demographics (Table 1) and clinical outcomes (Table 2) are presented. For 2020-2024 AHUP sites, the average time (mm:ss, SD) from 9-1-1 call to start of CPR was 9:09 (4:37) and time to start of AHUP CPR was 12:46 (5:57). The AHUP registry had a higher 5-yr incidence of SNF versus the CARES registry (difference 2.8%, 95% CI 1.8-3.8, p < 0.00001). This difference was consistent year over year (Figure 1). Secondary outcomes of sustained return of spontaneous circulation and survival to hospital discharge in the AHUP registry were also significantly higher than CARES registry data (Table 2). Conclusions: Over a 5-year period, an unadjusted analysis of aggregate data from two OHCA patient registries demonstrated that the incidence of survival with intact neurological function was higher in patients treated with AHUP CPR as part of first responder care versus patients treated with more conventional CPR methods.
Decentralized Biobanking to Empower Patient Engagement in Biospecimen Research: Operational Feasibility Case Study
Background: Biobanks often lack standard mechanisms to keep donors connected to their biospecimens, reflecting a broken feedback loop that compromises trust, engagement, and scientific progress. Decentralized biobanking empowers patients to track their donations throughout the research journey, supporting personalized feedback and research collaboration via a privacy-preserving blockchain network. This case study explores operational feasibility of implementing decentralized biobanking for a large breast cancer biobank at a US academic medical center. Methods: A mixed-methods case study of the groundwork, implementation, and stakeholder feedback for a real-world decentralized biobanking app pilot was conducted. Biobank members were recruited from February to April 2023. Operational feasibility was assessed via analysis of institutional stakeholder perspectives, pilot engagement, and de-bi app activity. Findings: Physicians and other biobank stakeholders surfaced challenges surrounding managing expectations, balancing empowerment with clinical and research workflows, and navigating power dynamics between patients, physicians, scientists, and leadership. A total of 1080 participants enrolled over 10 weeks, including nearly 10% of the biobank with about 4000 biospecimens. During the pilot, biobank enrollment increased 65% versus the prior year, and there were no biobank withdrawals during or within 1 year following the pilot ( p < 0.001 for both). The app, which facilitated biospecimen tracking and research engagement, was downloaded by 405 users. A total of 140 users tested the blockchain component, with 89% successfully claiming a nonfungible token representing their unique, immutable connection and access to donated biospecimens. Feedback was solicited to inform potential process improvements and risk assessments related to public relations, systems infrastructure, and ethical governance, illuminating next steps. Conclusions: We established operational feasibility for the first step toward decentralized biobanking, informed by requirements to manage expectations, workflows, and power dynamics. Our technical solution demonstrated robust participant engagement and compatibility with established biobanks, suggesting potential to build trust and align incentives and identifying next steps for communications, sustainability, and governance.