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Background. Early allograft dysfunction (EAD) affects outcomes in liver transplantation (LT). Existing risk models developed for deceased-donor LT depend on posttransplant factors and fall short in living-donor LT (LDLT), where pretransplant evaluations are crucial for preventing EAD and justifying the donor’s risks. Methods. This retrospective study analyzed data from 2944 adult patients who underwent LDLT at 17 centers between 2016 and 2020. We developed a logistic regression model to predict EAD based on this development cohort. We used data from 1020 patients at the King Faisal Transplant Center for external validation. Results. In the development cohort, 321 patients (10.9%) experienced EAD. These patients had poorer health status, more liver decompensation, and higher requirements of hospitalization than those without EAD. Multivariable logistic regression identified independent pretransplant predictors of EAD: laboratory Model for End-Stage Liver Disease score (odds ratio [OR], 1.08; 95% confidence interval [CI], 1.06-1.09), the necessity for hospitalization at the time of transplant (OR, 2.58; 95% CI, 2.00-3.30), and graft weight in kilogram (OR, 0.27; 95% CI, 0.17-0.45). Using these predictors, we developed the model for EAD after LDLT, which demonstrated strong discriminative ability in the development cohort with an area under the curve (AUC) of 0.71 (95% CI, 0.68-0.74). The model maintained high discrimination during internal validation (AUC, 0.70; 95% CI, 0.67-0.73) and showed a modest reduction in discriminative power in external validation (AUC, 0.65; 95% CI, 0.61-0.68). Conclusions. EAD post-LDLT is influenced by the recipient’s pretransplant health condition and the graft weight. Integrating the model for EAD after LDLT into the pretransplant process of pairing donors and recipients can enhance the safety and efficacy of LDLT.

556 Background: Combined hepatocellular carcinoma-cholangiocarcinoma (cHCC-CCA) is a rare and complex liver cancer with features of both hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), making its management challenging. This study aims to analyze the clinical characteristics, genomic profiles, and treatment outcomes of cHCC-CCA patients in a real-world setting. Methods: We conducted a retrospective analysis of cHCC-CCA patients across three first-line treatment groups: chemotherapy alone(Gemcitabine/Cisplatin, FOLFOX), HCC-directed therapies (atezolizumab/bevacizumab, lenvatinib, nivolumab, durvalumab, sorafenib), and chemoimmunotherapy (Gemcitabine/Cisplatin combined with immunotherapy). This international study, involving Mayo Clinic and the National Cancer Center East (Japan), assessed overall survival (OS) using Kaplan-Meier and Cox regression models. Results: A total of 68 patients were included, with a mean age of 66 years; 74% were male and 66% were White Non-Hispanics. Cirrhosis was present in 74% of patients at diagnosis, and Hepatitis B and C were common etiologies in 57%. Prior primary resection and regional therapies (Transarterial chemoembolization (TACE), Transarterial radioembolization (TARE)) were recorded in 39% and 50% of patients, respectively. Advanced/metastatic disease was present in 52% of the cohort. The distribution of first-line treatments was as follows: 47% received chemotherapy alone, 39% received HCC-directed therapy, and 14% received chemoimmunotherapy. Genomic alterations were detected in 44% patients, with TP53 (28%), ARID1A (25%), and TERT (22%) being the most frequent. The HCC-directed therapy group demonstrated the best overall response rate (52%) and had a median OS of 15.8 months (mo), compared to 11.8 mo for chemotherapy and 4.7 mo for chemoimmunotherapy (p=0.8). Patients who received regional treatments had a longer median OS of 15.8 mo compared to those who did not (10.2 mo) (p=0.4). Conclusions: HCC-directed therapy showed a trend towards better survival outcomes compared to other treatments, though not statistically significant. A considerable proportion of patients had genomic alterations, which may have influenced survival outcomes. Ongoing research with larger cohorts is underway to further elucidate the impact of genomic variations on treatment efficacy and refine therapeutic strategies for this challenging malignancy. Baseline characteristics of patients with combined hepatocellular carcinoma-cholangiocarcinoma (cHCC-CCA). Total(N=68) Mean age at diagnosis, years (SD) 66(6.4) Gender, n (%) Male 50 (74%) Ethnicity, n (%) White, Non-Hispanic 45 (66%) Cirrhosis at diagnosis, n (%) 50 (74%) Etiology of Liver disease, n (%) Viral (Hepatitis B and C) 39 (57%) History of Primary resection, n (%) 27 (39%) Regional treatment, n (%) 34 (50%) Afp, n (%) < 200 23 (64%) ca19_9, n (%) < 50 27 (82%)

732 Background: Ampullary carcinoma (AC) is a rare malignancy arising from the ampulla of Vater which has a more favorable prognosis compared to other pancreatic malignancies. Current guidelines favor surgical resection followed by adjuvant therapy for average risk patients (pts), however the type of regimen as well as other perioperative treatment modalities are still being explored. The objective of this retrospective study aims to provide insight into the management of locoregional disease. Methods: Pathology records from Mayo Clinic (AZ, FL, MN) denoting AC between 2010 to 2024 were searched using Mayo Data Explorer and selected for retrospective review. Pt demographics, treatment courses, and next generation sequencing (NGS) data were collected. Statistical analysis was conducted using SAS version 9.04. Results: A total of 137 pts (62% male, n = 85) were identified with median age 66 years old. Histologic subtypes were 54% pancreatobiliary (44/81), 40% intestinal (32/81), 6% mixed (5/81), with 56 pts unknown. Stages at diagnosis were 81% resectable (111/137), 11% locally advanced (15/137), and 8% metastatic (11/137). Nearly all (93%, n = 103/111) pts with localized disease had resection with a 97% R0 resection rate (100/103). Majority (68%, n = 75/111) of resectable pts had perioperative chemotherapy with 5-FU or gemcitabine-based regimens (24%, n = 18/75 neoadjuvant vs. 76%, n = 57/75 adjuvant). Perioperative chemoradiation was given in 17% (19/111) of pts. At median follow up of 30.5 months, recurrence rates were 40% (41/103), primarily to the liver (18/41). Median recurrence free survival (RFS) was 29.3 months (95% CI 24.7 – NE). Median overall survival (OS) has not been reached. The 5-year RFS and OS rates were 0.37 (95% CI 0.25 - 0.55) and 0.69 (95% CI 0.58 - 0.82), respectively. Univariate analysis showed no difference in OS with the addition of neoadjuvant or adjuvant chemotherapy or chemoradiation. Somatic NGS testing showed pathogenic mutations in 90% of pts (63/70): 57% KRAS (36/63; 44% G12D, 19% G12V, 8% G12C, 8% G12D, 19% others); 13% homologous recombination (HR) (8/63); 6% ERRB2 /Her2 amplification (4/63), and 5% mismatch repair (MMR) (3/63). Conclusions: AC has a favorable prognosis in resectable pts. However, high recurrence rates indicate the need for better systemic therapies and improved selection of pts who would benefit from these treatments. Future research should focus on refining perioperative strategies to enhance outcomes and reduce recurrence.

Abstract Rationale Optogenetics offers unmatched cellular specificity and control over cellular activity. Various opsins have been tested in animal models of epilepsy, each contributing to our understanding of seizure circuit dynamics. However, inhibitory optogenetic tools based on microbial rhodopsins have low light sensitivity and, thus, are less suitable for applications involving larger brains. We evaluated eOPN3, a red-shifted, highly sensitive inhibitory G-protein coupled receptor opsin in a porcine seizure model using integrated electro-optical sensing and modulation. The results demonstrated the feasibility of eOPN3 circuit modulation in a large animal epilepsy model. Methods MRI-guided stereotactic surgery was used to deliver 20–60 µL of AAV-eOPN3 (AAV5-/AAV9-CaMKII-eOPN3-mScarlet) into the hippocampus (HPC) of three Göttingen minipigs. Each hemisphere received either an active or a control viral vector (AAV5/9-CaMKII-mScarlet) with gadolinium to visualize the injection sites and diffusion volume via post-operative MRI. Two to three months post-injection, bilateral deep brain stimulation electrodes integrated with optic fibers were stereotactically implanted into the anterior nucleus of the thalamus (ANT) and HPC to assess: 1) opsin expression using fiber photometry, 2) optogenetic modulation of stimulation evoked response potentials (SERPs), 3) induction and propagation of seizure-like activity via intrahippocampal kainic acid (KA) injection, and 4) optogenetic modulation of KA-induced seizure activity. After the electrophysiology recording, brains were harvested for histological analysis to evaluate injection target precision, eOPN3 expression, and estimate eOPN3-modulated volume. Results eOPN3 expression was confirmed during surgery via fiber photometry. ANT electrical stimulation elicited robust SERPs in the HPCs, which were attenuated by HPC light illumination. HPC stimulation similarly induced SERPs in the ipsilateral ANT and the contralateral HPC. The HPC stimulation-induced SERPs were significantly reduced by illuminating the site of the recording areas, the ipsilateral ANT and the contralateral HPC, demonstrating the optogenetic inhibition of the synaptic release from the HPC. KA injection into the HPC induced 20-30 Hz seizure-like activity. The ANT and HPC light illumination suppressed the localized KA-induced seizure activity in the early stage. However, after the generalization of KA-induced seizures, the ANT-HPC illumination lost efficacy for the control of seizures. Histological analysis confirmed eOPN3 expression in the HPC, ANT and other Papez circuit nodes. Conclusion Our pilot study highlights that eOPN3-mediated inhibition alters SERP and the latency and spread of KA-induced seizure-like activity. We developed a platform incorporating pre- and postoperative MRI for precise viral vector delivery, real-time fiber photometry for quantifying opsin expression, and integrated electro-optical sensing and stimulation to assess optogenetic efficacy in a large animal model. The large animal model provides a solid foundation for future translational research to develop electro-optical devices and cellular therapies for human epilepsy.

Abstract Translational large-animal models that can accommodate human-scale implantable devices are essential for advancing neuromodulation therapies in epilepsy. This study establishes a kainic acid (KA)-induced porcine model of mesial temporal lobe epilepsy (mTLE) using clinical imaging, stereotactic surgery, and a fully implantable neural stimulation and recording (INSR) device designed for humans. Seven pigs (six KA-treated and one saline control) underwent MRI-guided stereotactic implantation of electrodes targeting bilateral hippocampus (HPC) and anterior thalamus (ANT), followed by intra-hippocampal KA or saline infusion. Local field potentials (LFP) were recorded continuously with synchronized video monitoring. Seizures and LFP interictal epileptiform-like discharges (IEDs) were quantified using validated automated detectors. Histology was performed in the saline control and the longest surviving KA-treated pig. Intra-hippocampal KA infusion induced acute status epilepticus in all (6/6) treated pigs. Four animals survived to chronic monitoring with spontaneous seizures observed in three pigs (2,733 seizures; mean duration of 27.2 ± 17.6 seconds). IEDs were observed in bilateral HPC of all animals, including saline control, with higher rates in the lesioned HPC (p <0.0001). While the IED morphology is consistent with epileptiform activity; IEDs alone are not specific for epilepsy and physiological transients (e.g. sharp-wave ripples) and injury-related hyperexcitability or strain-specific hyperexcitability cannot be excluded. Histological analysis revealed patchy neuronal loss and cytoarchitectural changes in HPC. This porcine model reproduces electrophysiological features of human mTLE. This approach provides a powerful translational bridge for developing and testing next-generation INSR and neuromodulation strategies in freely behaving large animals.

ABSTRACTBackgroundOlfactory neuroblastoma (ONB) is a rare sinonasal malignancy primarily treated with surgery. For tumors arising from the olfactory area, traditional treatment involves transcribriform resection of the anterior cranial fossa. Surgery can be performed with unilateral or bilateral resection depending on extent of involvement; however, there are currently no studies comparing outcomes between the two.MethodsProspective and retrospective data on primary ONB patients were collected from a multicenter registry involving eight academic sites. Propensity score matching (PSM) was used to create patient cohorts with similar baseline characteristics. Cox proportional hazards and Kaplan Meier analyses assessed overall survival (OS). Logistic regression assessed associations between extent of resection (unilateral versus bilateral) and tumor recurrence or postoperative cerebrospinal fluid (CSF) leak.ResultsA total of 187 ONB patients (47.6% female) with an average age of 53.6 ± 15.1 years were analyzed. Most tumors were unilateral (81.3%) and predominantly Kadish C (58.3%) or Hyams II (55.8%). Overall, 56.7% of patients underwent bilateral resection. Fifty‐four patients experienced tumor recurrence and nine had postoperative CSF leaks. Following PSM (n = 45/group), extent of resection was not associated with mortality (hazard ratio [HR] 1.73; p = 0.407) or OS (p = 0.400). There was no association between extent of resection and recurrence (odds ratio [OR] 0.90; p = 0.814) or postoperative CSF leak (OR 1.54; p = 0.647).ConclusionsFor ONB tumors where unilateral resection may be feasible and oncologically sound, the decision for unilateral versus bilateral resection showed no significant effect on survival, recurrence, or postoperative CSF leak. Oncologic outcomes may be comparable when resection is tailored to individual patient and tumor characteristics.

Background Sinonasal mucosal melanoma has poor survival despite multimodality treatment. While the impact of immunotherapy (IT) on metastatic cutaneous melanoma is well-defined, there are relatively little data on sinonasal mucosal melanoma. Objective We sought to define immunotherapy outcomes in patients with sinonasal mucosal melanoma. Methods A retrospective cohort study evaluated patients treated with IT during their overall treatment strategy for SNMM. Patient demographics, treatment, and survival outcomes were recorded. Results 52 patients had IT treatment for SNMM from 2000 to 2022, with an average age of 69.1 ± 11.9 years. The most common treatment was surgery with radiation and IT ( n = 26, 50%). Most regimens consisted of a combination of Nivolumab and Ipilimumab ( n = 17, 32.7%) or pembrolizumab ( n = 14, 26.9%). 44.2% of patients experienced reported complications. Overall survival at 1-, 2-, and 5 years was 86.9%, 74.1%, and 39.1%, respectively. Conclusion Approximately half of patients will have a local response following immunotherapy, but it is rare to have improvement at metastatic locations. Further research within our group will assess optimal timing and markers that are predictive of response.

AbstractBackgroundAccumulation of the amyloid‐β (Aβ) peptide into amyloid plaque is one of the key pathological markers of Alzheimer’s disease (AD). Apolipoprotein E (APOE) is known to modify AD risk and has been reported to influence Aβ accumulation in the brain in an isoform‐dependent manner. ApoE can be produced by various cell types in the brain, with astrocytes being the main producer. Increasing studies show that altering apoE levels can influence Aβ plaque pathology. However, it is not fully understood how apoE produced by specific cell types, such as astrocytes, contributes to amyloid pathology.MethodWe utilized mouse models expressing APOE isoforms in astrocytes and crossed them with 5xFAD mouse models of amyloidosis. We analyzed the changes to amyloid plaques and assessed the impact on cellular responses to amyloid plaques in condition of astrocytic APOE expression.ResultSpecific expression of APOE3 in astrocytes resulted in compact amyloid plaques and a large increase in plaque deposition, while the total plaque burden was reduced. Astrocytic APOE2 expression led to similar changes to amyloid plaques, but the fold change is lower comparing to that in astrocytic APOE3 models. Intriguingly, the total microglial response increased dramatically in condition of astrocytic APOE3 expression but not in condition of astrocytic APOE2 expression. Further, the ratio of plaque associated Lgals3/Iba1 is higher in condition of astrocytic APOE3 expression, indicating increased microglial activation. Additionally, astrocyte GFAP levels only increased in astrocytic APOE3 models, but not in astrocytic APOE2 models. Finally, APOE isoform effect on dystrophic neurites amount was also observed.ConclusionTogether, our study reveals an important role of astrocytic APOE on the deposition and accumulation of Aβ plaques as well as on Aβ‐associated downstream effects.

AbstractBackgroundProgressive supranuclear palsy (PSP) is a neurodegenerative disorder involving pathological deposition of tau that includes glial inclusions and specific regional vulnerability patterns. Therapeutic developments are hampered by incomplete understanding of disease mechanisms. Few studies have examined its cell type‐specific effects. We performed RNA‐sequencing in a large cohort of PSP patients and controls to understand molecular pathways disrupted across prefrontal cortex and caudate nucleus in PSP. We also performed multi‐omic single‐nucleus sequencing to deconvolute cell type‐specific changes.MethodRNA‐sequencing was conducted in 250 PSP patients and age‐ and sex‐matched controls, with a subset (N = 23) undergoing multi‐omic single‐nucleus RNA‐sequencing and ATAC‐sequencing (10x Genomics). Sequencing data was aligned to GRCh38 and quantified using STAR and RSEM (RNA‐seq) and CellRanger (single‐nucleus) and corrected for technical and biological covariates. Differential expression was calculated with Dream (RNA‐seq) and Dreamlet (single‐nucleus sequencing), and co‐expression network analysis (WGCNA) used to extract disease‐relevant gene modules.ResultRNA‐sequencing analysis identified ∼4000 differentially expressed genes in both brain regions. Despite differences in cellular composition and degree of disease impact, both regions share patterns of dysregulation related to protein folding and processing, indicating common pathological mechanisms. Differences between the regions includes disruption of cellular homeostasis and intracellular trafficking in caudate, while prefrontal cortex shows suppression of metabolic processes and immune response. Preliminary findings from the single cell genomic analyses suggest the greatest changes occur in neurons of both regions, where there is a shared pattern of protein processing dysregulation and a distinct enrichment in metabolic processing within prefrontal cortex interneurons.ConclusionWe identified thousands of dysregulated genes in two impacted brain regions in PSP and show that this dysregulation is reflected in specific neuronal populations in these regions. Identifying regional and specific cell type‐specific mechanisms related to PSP will further our understanding of causative disease mechanisms and provide new avenues for therapeutic developments.