Brexucabtagene-autoleucel (brexu-cel) produces high rates of measurable residual disease-negative (MRD-) complete response (CR) in adults with Philadelphia-chromosome positive (Ph+) acute lymphoblastic leukemia (ALL); however, subsequent relapses remain frequent. It is unclear whether maintenance with tyrosine kinase inhibitors (TKIs) can enhance remission durability. We evaluated outcomes among adults with relapsed/refractory Ph+ ALL who received commercial brexu-cel and achieved MRD- CR across 19 U.S. institutions. Considering TKI maintenance as a time-varying covariate, we analyzed outcomes based on receipt of subsequent TKI maintenance versus no maintenance. Patients receiving consolidative transplantation or non-TKI maintenance were excluded. Fifty-one patients were included: 20 received TKI maintenance and 31 received no maintenance. The use of TKI maintenance was associated with a significantly lower 1-year cumulative incidence of relapse (HR 0.12; 95% CI, 0.02-0.88; p=0.037) which translated into improved progression-free survival (PFS, HR 0.19; 95% CI, 0.04-0.85; p=0.029) and a trend towards improved overall survival (OS, HR 0.34; 95% CI, 0.07-1.62; p=0.18). There was no difference in non-relapse mortality (NRM, HR 0.83; 95% CI, 0.12-5.87; p=0.85). This real-world analysis supports the administration of TKI maintenance in Ph+ ALL following achievement of MRD- CR with brexu-cel as a strategy to improve PFS following chimeric antigen receptor T cell therapy.
Exploring Healthcare Continuity in Pediatric‐Onset Multiple Sclerosis in the United States
ABSTRACT Objective Little is known about shifting from pediatric to adult‐focused multiple sclerosis (MS) care. This study aims to explore transition of care and follow‐up in the US pediatric‐onset MS (POMS) population. Methods Surveys were distributed to 10 sites in the US Network of Pediatric MS Centers (US NPMSC) about transition‐of‐care practices. A cohort of POMS/clinically isolated syndrome (CIS) at 12 US NPMSC sites was analyzed. The primary comparison was between < 18 and ≥ 18‐years of age. The primary outcome was 1‐ and 2‐year lapse in last follow‐up visit, measured from last recorded database visit to data lock date or, if ≥ 18 years of age, up to 1 year after a patient reached their site's typical transition age, if earlier. Secondary outcomes were baseline factors associated with follow‐up lapse. The model was adjusted for preidentified confounders. Results Compared with < 18 years, age ≥ 18 was associated with greater hazard of 1‐ and 2‐year follow‐up lapse. In POMS/CIS, the estimated hazard was 1.61 for 1‐year lapse (95% confidence interval [CI] 1.32–1.97, p < 0.001) and 1.40 for 2‐year lapse (95% CI 1.11–1.76, p = 0.004). In POMS‐only, the estimated hazard was 1.70 for 1‐year lapse (95% CI 1.33–2.18, p < 0.001) and 1.49 for 2‐year lapse (95% CI 1.11–1.99, p = 0.007). Platform injectable disease‐modifying therapy was associated with greater and intravenous with lesser hazard of lapse in follow‐up, while MS was associated with lower hazard than CIS. Conclusion Variable transition‐of‐care practices and barriers were reported by major US POMS centers. Before typical transition age, age ≥ 18 was associated with greater hazard of 1‐ and 2‐year follow‐up lapse than < 18. Developing standardized, targeted transition‐of‐care practices in POMS may be important.
FP47 Adolescent normative values for body surface gastric mapping: spectral analysis
Abstract Background and Objectives Cholangiocarcinoma (CCA) is an aggressive, highly lethal cancer of the biliary tract epithelium for which tumor resection is the only curative treatment. However, approximately half of patients present with nonresectable disease and median survival of these patients is just 8-12 months. A significant need exists for tumor-targeted therapeutics for patients with advanced disease who currently have limited treatment options. We aimed to address this need by developing an aptamer-targeted therapy for delivery of siRNAs inhibiting undruggable components of the Hippo pathway, a key driver of cholangiocarcinoma. Method We applied cell-SELEX against human CCA model cell line HuCCTl with negative selection against normal hepatocytes and cholangiocytes to identify an aptamer that selectively bound tumor cells. This aptamer, termed MC7122, was chemically modified to include fluorescent labels that enabled whole-animal biodistribution studies to assess in vivo selectivity. MC7122 was then deployed onto the surface of siRNA-loaded nanovesicles to drive tumor-targeted nucleic acid delivery. Tumor-bearing mice were treated with siRNAs three times per week for two weeks alone or in combination with standard of care chemotherapy. Results Combined treatment with siRNAs and standard of care chemotherapy reduced tumor burden in mice versus vehicle controls and slowed the spread of metastasis. Importantly, we found tumor-specific target gene knockdown without corresponding off-target knockdown in healthy surrounding liver tissue. Further, we demonstrated that sites in the lung, the primary location of metastasis in this model, were reduced not because of global target knockdown in lung but due to tumor-specific knockdown at the site of liver implantation. Conclusions Aptamer-guided vesicles represent a promising platform for targeted therapy delivery for previously undruggable targets. With this platform, tumor-selective therapies can be designed to exhibit exceptionally potent cytotoxicity, as healthy tissues remain unaffected by off-target effects. Future work will focus on refinement of therapeutic siRNA target selection and modification of nanovesicle components for enhanced levels of tumor specificity.
18Concurrent ARID1A/PBRM1 loss reorganizes chromatin accessibility through SWI/SNF complex redistribution in Cholangiocarcinoma
Abstract Background Cholangiocarcinoma (CCA) is an aggressive primary liver cancer with remarkable molecular heterogeneity. Mutations in SWI/SNF chromatin remodeling components occur in > 20% of CCA cases, with ARID1A and PBRM1 being significantly co-mutated. However, how the dual loss of these subunits reshapes chromatin architecture and drives oncogenic programs remains unclear that we aimed to address by profiling SWI/SNF redistribution, chromatin accessibility, 3D chromatin structure, and transcriptome in a dual Arid1a/Pbrm1 knockout mouse model. Methods CCA was induced in Cas9 knock-in mice via biliary instillation of myr-AKT along with sgRNAs targeting Arid1a and Pbrm1, generating APAC cell line. AC cell line was derived from mice receiving myr-AKT alone. Isogenic dual knockout (AC-sgAP) and control (AC-NT) lines were then generated from AC cells. Multi-omics profiling included ChIP-seq for SMARCA4/BRG1 and DPF2, ATAC-seq, RNA-seq, and Hi-C. Results ChIP-seq revealed that AC-sgAP cells showed decreased BRG1 binding (9,217 vs. 20,769 peaks) but increased DPF2 binding (7,527 vs. 2,068 peaks) and co-occupancy (5,037 vs. 1,888 peaks) compared to AC-NT. In contrast, APAC cells exhibited depletion of both BRG1 (12,994 peaks) and particularly DPF2 (146 peaks) with minimal overlap (68 shared peaks). Genome-wide accessibility profiling demonstrated that APAC cells had 78,582 differentially accessible regions compared to AC-NT, the majority (>70%) representing loss of accessibility, whereas AC-sgAP cells showed only 6,587 differentially accessible regions. Transcriptional profiling identified both unique and common significantly differentially expressed genes in APAC and AC-sgAP relative to AC-NT controls. Interestingly, topologically associating domains (TADs) calling revealed that AC-sgAP cells displayed approximately three-fold more differential TADs compared to AC-NT than APAC cells relative to controls. Conclusions Concurrent Arid1a/Pbrm1 loss drives extensive chromatin and transcriptional reprogramming through SWI/SNF redistribution. APAC cells achieving greater transcriptional dysregulation with fewer TAD disruptions might suggest that intra-TAD regulatory changes are critical events in SWI/SNF-mutant cholangiocarcinoma.
3BAP1 loss confers ferroptosis resistance to cholangiocarcinoma via TLCD1-mediated mitochondrial membrane phospholipid remodeling
Abstract Background Cholangiocarcinoma (CCA) is a deadly cancer of the hepatic bile duct epithelial cells. Loss-of-function mutations of epigenetic regulator ubiquitin C-terminal hydrolase deubiquitinase BRCA1associated protein 1 (BAP1) occur in 26-32% of human CCA and are associated with worse prognosis and resistance to cytotoxic therapy. The goal of this study is to identify how BAP1 loss promotes cell death evasion through metabolic rewiring. Materials and methods Isogenic wild-type and BAP1-deficient human and murine CCA cell lines were generated with shRNA/siRNA or CRISPR/Cas9 and were used to assess ferroptosis sensitivity by treatment with ferroptosis inducers. In vitro, ferroptosis was assessed by phospholipid peroxidation (C-11BODIPY), mitochondrial phospholipid peroxidation (MitoPeDPP, MitoCLox), iron overload (MitoFerro green) and cell death (CellTiter-Glo). Phospholipidomics and proteomics were performed in isogenic cells by LC-MS/MS. Syngeneic liver orthotopic CCA murine models and patient-derived xenografts (PDX) were used for in vivo pre-clinical studies. Results Our findings indicate that BAP1 loss confers CCA ferroptosis resistance. BAP1 loss protects CCA against mitochondrial iron overload, ROS accumulation, and phospholipid peroxidation. BAP1 loss protects from mitochondrial phospholipid peroxidation and cardiolipin oxidation. Unbiased phospholipidomic profiling revealed that BAP1 loss remodels membrane phospholipid composition, enriching for ferroptosis blocking monounsaturated phospholipids (MUFA-PLs) at the expense of ferroptosis-inducing polyunsaturated (PUFA-PLs). We found that BAP1 loss upregulates TLCD1, a phosphatidylethanolamine acyltransferase that incorporates MUFAs into membrane phospholipids, thereby stabilizing membranes against peroxidation. TLCD1 knockdown in ferroptosis-resistant BAP1-deficient CCA cells, restored ferroptosis sensitivity. Notably, TLCD1 is significantly upregulated in human BAP1-mutant CCA as compared to BAP1-expressing tumors. While not a mitochondrial protein, TLCD1 localizes in the ER and by the mitochondrial outer membrane, as demonstrated by our immunofluorescence analysis in human CCA cells. From a therapeutic perspective, we developed EpCAM (adhesion molecule highly expressed in CCA cells)-aptamer coated lactosomes packaged with siRNA against glutathione peroxidase 4 (GPX4), as a proof-of-concept strategy to safely induce ferroptosis selectively in CCA in vitro and in vivo. Administration of siGPX4-lactosomes in pre-clinical syngeneic liver orthotopic CCA murine models demonstrated a favorable safety profile, achieved robust intratumoral GPX4 knockdown (>50%), exhibited optimal biodistribution, induced significant tumor lipid peroxidation, and resulted in reduced tumor burden. Lastly, ferroptosis inducer JKE-1674, combined with gemcitabine/cisplatin (Gem/Cis) significantly blocked tumor growth of Gem/Cis-resistant patient-derived xenografts. Conclusions Our findings reveal that BAP1 loss reprograms mitochondrial phospholipid metabolism thus conferring CCA resistance to ferroptosis, identifying TLCD1 as a targetable metabolic vulnerability in BAP1-mutant CCA. Additionally, our findings support ferroptosis inducing compounds as promising therapeutic approaches for CCA.
13Clinical features and transcriptomic landscape of SWI/SNF-mutated biliary tract cancers
Abstract Background SWI/SNF chromatin remodeling complexes are frequently mutated across human cancers, including biliary tract cancers (BTC). Within the SWI/SNF complexes, loss-of-function (LOF) mutations in ARID1A and PBRM1 are the most common and frequently co-occur alongside PI3K/AKT pathway activation. Yet, how those mutations affect the intracellular signaling landscape and transcriptomic programs is underexplored and may yield novel therapeutic opportunities. Methods Clinicodemographic parameters and mutation profiles of 250 patients with BTC were retrospectively collected through electronic medical records. Advanced overall survival (OS) was assessed in a multivariable analysis. Transcriptomic data were obtained and differentially expressed genes (DEGs) and pathways associated with SWI/SNF mutation status were analyzed. Changes in the transcriptomic landscape were compared to a murine syngeneic model of intrahepatic cholangiocarcinoma (CCA) initiated by loss of ARID1A and/or PBRM1 for cross-species validation. Results After adjusting for age, sex, and anatomical subtype, patients with SWI/SNF LOF mutations were found to have a 30% reduction in mortality risk (HR = 0.70, 95% CI: 0.50-0.98, p = 0.037). The transcriptomic cohort of 233 BTC patients included 71 (30%) with SWI/SNF LOF mutations, 21 (9%) with variants of uncertain significance, and 141 (61%) with SWI/SNF wild-type tumors. Differential gene expression and pathway analysis revealed changes in adaptive immune response, extracellular matrix, and cancer-associated proteoglycans. RNA-sequencing of murine tumors revealed the dominant effect of ARID1A loss in single and double knock-out tumors and conserved pathway alterations between mouse and human tumors. Conclusion Both murine and human primary tumors with either ARID1A alone or ARID1A/PBRM1 co-mutations exhibited altered expression of critical genes and pathways associated with proteoglycan synthesis and extracellular matrix. Ongoing research is investigating how CCA cells depend on those pathways and their canonical regulators for tumor formation and progression.
38AI Starter: Medical Image Analysis for Cholangiocarcinoma Projects
Abstract Background & Objectives Cholangiocarcinoma (CCA) is a rare and aggressive malignancy of the bile ducts characterized by complex imaging patterns, high inter-reader variability, and limited subspecialty expertise. Despite the critical importance of early detection for improving patient outcomes, most artificial intelligence (AI) tools developed for radiology have focused on other organ systems, leaving CCA largely underserved. Furthermore, clinicians with relevant domain expertise frequently lack the programming background required to participate meaningfully in AI development. This work aimed to create an accessible, educational AI framework “AI Starter” designed to empower radiologists and clinicians to initiate medical image analysis projects for CCA without requiring extensive coding knowledge. Methods A structured, end-to-end AI pipeline was introduced covering the key stages of image acquisition, preprocessing, segmentation, feature extraction, and predictive modeling. Open-source frameworks, specifically MONAI and PyTorch, were employed to ensure reproducibility and accessibility. Transfer learning strategies were incorporated to address the challenge of limited CCA-specific training datasets. The pipeline was designed with modular components to reduce technical barriers and accommodate users across varying levels of computational experience. Results Radiologists and clinicians were able to successfully engage with and deploy AI tools for CCA imaging analysis using this framework. Transfer learning demonstrably improved model performance under data-limited conditions, and the open-source implementation supported reproducible research workflows. Key challenges identified included scanner variability, segmentation instability, feature instability, and model overfitting, all of which were transparently mapped within the pipeline. Conclusion The AI Starter framework offers a practical and educational entry point for the CCA community including basic scientists and clinicians to meaningfully engage with and understand AI-driven imaging analysis.
Clinical Associations of Cerebrospinal Fluid TMEM106B in Familial and Sporadic Frontotemporal Dementia
Importance TMEM106B is a frontotemporal lobar degeneration (FTLD) genetic susceptibility factor, and TMEM106B protein aggregates are a feature of aging and neurodegeneration. Whether TMEM106B protein levels are associated with clinical features is unknown. Objective To investigate the clinical associations of cerebrospinal fluid (CSF) TMEM106B in FTLD. Design, Setting, and Participants This cross-sectional study was conducted in 2 independent frontotemporal dementia (FTD) cohorts (recruitment from April 2009 through July 2023, with analyses from January 2025 through April 2026), with a 2-year follow up. This multicenter clinical study integrated clinical, genetic, biomarker, and neuroimaging data. Individuals were recruited through the University of California, San Francisco (n = 3733), or ALLFTD (n = 2343). Participants with available CSF were included. A discovery cohort (n = 271) included participants with sporadic neuropathology-confirmed FTLD; presymptomatic or symptomatic carriers of pathogenic variants in C9orf72 , GRN , or MAPT ; or controls. An independent validation cohort (n = 383) included participants with clinically diagnosed sporadic FTD, Alzheimer disease (AD), and controls. Exposures CSF samples for TMEM106B quantification with aptamer proteomics (SomaScan version 3.0 [discovery cohort] and SomaScan version 4.1 [validation cohort]). Main Outcomes and Measures Parametric tests compared the primary outcome, CSF TMEM106B, by disease severity, TMEM106B rs1990622 genotype, sex, clinical syndrome, pathological diagnosis, and pathogenic variant and determined associations with brain volume. Results In the discovery (n = 271; 136 women [51%]; median [IQR] age, 59 [38-80] years) and validation (n = 383; 183 women [48%]; median [IQR] age, 64 [50-78] years) cohorts, lower CSF TMEM106B was associated with more severe disease (β, −0.15; 95% CI, −0.24 to −0.04; P = .003), lower frontotemporal brain volumes (β, 0.42; 95% CI, 0.24-0.61; P &lt; .001), and faster clinical progression (β, −2.21; 95% CI, −3.70 to −0.72; P = .001). Associations of TMEM106B with clinical disease severity were independent of those with neurofilament light chain. TMEM106B levels were influenced by TMEM106B rs1990622 genotype, where individuals with the protective G/G genotype had lower levels than the risk A/A genotype. CSF TMEM106B levels did not differentiate between FTLD subtypes or between FTLD and AD. Conclusions and Relevance Per the results of this cross-sectional study, TMEM106B is detectable in CSF and levels reflect disease severity in sporadic and genetic FTLD and AD, but levels are also influenced by the TMEM106B rs1990622 genotype. CSF TMEM106B could support further studies to understand the mechanisms of disease and develop clinical tools in FTLD and other neurodegenerative diseases.
Thalamocortical seizure onset patterns in drug-resistant focal epilepsy
Abstract Drug-resistant epilepsy affects tens of millions of people worldwide and is associated with considerable morbidity and mortality. Thalamic deep brain stimulation and cortical responsive neurostimulation are proven treatments for focal epilepsy. Both have been used to target a range of thalamic nuclei; yet, the roles of these thalamic nuclei in focal seizure generation remain incompletely understood. Thirteen patients with drug-resistant focal epilepsy undergoing intracranial EEG were consented to undergo investigation of thalamocortical networks. Sampled regions included cortical, mesial temporal, and thalamic brain regions. Visual and spectral analyses were performed to identify seizure onset patterns and correlate thalamic and cortical seizure activity. Thalamic ictal discharges were observed in 89% of seizures. Of these, 56% demonstrated synchronous thalamocortical activity with distinct patterns. These onset patterns included hypersynchronous spiking, low-voltage fast activity, ictal baseline shifts, and broadband suppression. Multiple thalamic nuclei were involved in ictal organization and propagation, with the specific nuclei depending on the cortical seizure network. The thalamus plays a crucial role in focal onset seizure generation and propagation, with distinct seizure onset patterns and nuclei involved. These findings support exploring a broader range of thalamic nuclei in epilepsy neurostimulation and have implications for seizure detection settings in intracranial sensing devices.