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830 Background: Immune checkpoint inhibitors (ICIs) are standard therapy for MSI-H GI cancers. Lynch syndrome, caused by germline mutations in mismatch repair (MMR) genes, leads to MSI-H tumors and robust ICI responses, but its effect on irAEs remains poorly defined. Clarifying this risk may inform treatment selection and toxicity monitoring. Methods: We retrospectively reviewed MSI-H or MMR-deficient (dMMR) GI cancer patients (pts) treated with ICIs across Mayo Clinic (AZ, MN, FL) from January 2017 to June 2025. Eligible pts were identified using Mayo Data Explorer. Demographics, treatment, and irAEs (graded per CTCAE v5.0) were collected. Lynch status was determined by germline testing when available. Logistic regression estimated odds ratios (ORs) for any grade and grade ≥3 irAEs, adjusting for age, cancer type, prior chemotherapy, and treatment regimen. Results: A total of 209 pts with dMMR/MSI-H GI cancer were included: 61 with Lynch syndrome and 148 without. Lynch pts were younger (median 58 vs 76 years, p < 0.001) and more likely to have received prior chemotherapy (62% vs 43%, p = 0.009). Colorectal cancer was the predominant cancer type (74%), but Lynch pts had proportionally more non-colorectal GI cancers (15% vs 2.7%, p = 0.007). Overall, 29% of pts experienced an irAE, with rates significantly higher in Lynch vs non-Lynch pts (43% vs 24%, p = 0.005). The most frequent irAEs were gastrointestinal, endocrine, and dermatologic, followed by hepatic and pulmonary events. Grade ≥3 irAEs occurred in 16% overall, with no significant difference between groups (p = 0.124). In adjusted models, Lynch syndrome was independently associated with a higher risk of any grade irAE (OR 2.14, 95% CI 1.09 - 4.19, p = 0.026), while risk of severe irAEs was not increased (OR 1.55, 95% CI 0.64 - 3.59, p = 0.316). Lynch syndrome pts were more likely to have combination therapy (17% vs 6.8%, p = 0.029). However, there were no differences observed in any grade irAE between monotherapy and combination immunotherapy (OR 1.36, 95% CI 0.49 - 3.54, p = 0.535). Conclusions: Lynch syndrome is associated with a higher prevalence of any-grade irAEs among dMMR/MSI-H GI cancer pts treated with ICIs, though severe events were not increased. Incorporating Lynch status into immunotherapy planning may improve risk stratification and guide regimen selection.

817 Background: Universal germline sequencing is increasingly utilized in practice, but existing evidence and guidelines are based on studies in predominantly white populations. This study aims to compare the prevalence of genetic alterations in white vs underrepresented minority (URM) populations and assess incremental findings discovered with universal testing beyond current guidelines. Methods: This prospective, multicenter study analyzed genetic alterations in white and URM cohorts with primary GI malignancies receiving care at Mayo Clinic cancer centers between April 2018 and April 2025. Patients underwent germline sequencing using a next-generation sequencing (NGS) platform targeting over 80 genes. We compared the distribution of results between white and URM populations. Concordance with NCCN testing guidelines and incremental findings were assessed. Results: A total of 1128 patients were studied, of which 758 were white and 370 were URM, (47.6% Hispanic, 22.7% Black, 13.8% Asian, 10.5% American Indian, 0.8% Pacific Islander, and 6.8% other). Pathogenic variants (PGV) were more common in the white population (16.1% vs 9.2% P < 0.001). Variants of uncertain significance (VUS) were more common in the URM population (53.2 vs 43.5%, P<0.001). A total of 156 patients were found to have a PGV. PGVs outside primary cancer genes were more common in white patients (57.4% vs. 32.4%; p=0.0241). Incremental findings from universal testing were higher in white patients (66.4% vs 35.3%; p=0.0011). Conclusions: This study reveals a significant difference in the prevalence of PGV and VUS between white and URM patients with primary GI malignancies. The higher rate of PGVs in white patients and VUS in URM patients highlights potential inequities in both detection and interpretation of genetic results. These findings emphasize the need for broader representation in genetic databases to ensure equitable access to precision oncology. Screening guidelines met by patients with PGV. White (N=122) URM (N=34) Total (N=156) p value Did they meet NCCN testing guidelines for their primary cancer? 0.0991 Yes 87 (71.3%) 29 (85.3%) 116 (74.4%) No 35 (28.7%) 5 (14.7%) 40 (25.6%) Was the PGV outside of the primary genes recommended for their primary cancer? 0.0241 Yes 70 (57.4%) 11 (32.4%) 81 (51.9%) No 47 (38.5%) 22 (64.7%) 69 (44.2%) Incremental Finding 0.0011 Yes 81 (66.4%) 12 (35.3%) 93 (59.6%) No 41 (33.6%) 22 (64.7%) 63 (40.4%)

679 Background: DNA-damaging agents improve outcomes in metastatic pancreatic cancer (mPC) with homologous recombination repair (HRR) deficiency, albeit use is limited to 6-9% of patients (pts) with BRCA1/2 or PALB2 mutations. We hypothesized that BRCA/PALB2 wildtype mPC may exhibit platinum sensitivity driven by altered HRR gene expression. We correlated HRR gene RNA profiles with real-world overall survival (rwOS) following first-line (1L) platinum therapy (PT). Methods: Tempus Lens, a platform used to query multimodal data from millions of de-identified patient records in the Tempus Database was used to identify mPC pts with wildtype somatic BRCA1/2 and PALB2 who had Tempus xT DNA and xR RNA testing. RNA-seq data were normalized to correct for assay/batch effects, quantified as transcripts per million (TPM) and reported as log2(TPM+1) for 17 HRR genes and GATA6 . Pts were classified as high and low expressors based on the top and bottom quartile gene expression. Pts were grouped as PT-treated (received 1L PT) or PT-naïve (never received PT). Real world overall survival (rwOS) was calculated from 1L start to death or loss to follow up. Risk set adjustment was applied to mitigate immortal time bias. Median rwOS was estimated using Kaplan-Meier and univariate Cox models. A multivariate Cox Proportional (CoxPh) model included PT use, RAS status, and expression of genes (as continuous variables). Results: Among 1,068 pts, the median age was 66 years and 609 (57%) received 1L PT. In low RAD51 expressors, PT-treated pts (n=136) had significantly longer rwOS than PT-naïve (n=112): 11.4 months (95% CI, 7.8–13.8) vs 8 months (95% CI, 5.5–9.0); p=0.028. In contrast, in high RAD51 expressors, rwOS was similar between PT-treated (n=150) and PT-naïve (n=97): 7.9 vs 6.9 months (p=0.236). High GATA6 expression was also associated with improved rwOS in PT-treated pts vs PT-naïve: 13.5 vs. 9.3 months; p=0.011. In multivariate analysis, increased GATA6 expression remained a positive predictor of rwOS (HR 0.82; 95% CI, 0.76–0.88; p<0.001), and high RAD51 expression was associated with shorter rwOS with PT (HR 1.18; 95% CI, 1.01–1.39; p=0.043). Conclusions: In BRCA/PALB2 wt mPC, transcriptomic profiling identified low RAD51 and high GATA6 expression as predictors for improved rwOS when treated with PT. Integrating these biomarkers may improve development of DNA-damaging therapies beyond canonically defined HRD. Hazard ratios of mPC mortality by selected HRR genes estimated by multivariate CoxPh models. HR 95% CI p value 1L PT (vs PT-naïve) 0.87 0.75, 1.00 0.054 BRCA1 1.15 0.98, 1.35 0.079 BRCA2 0.89 0.77, 1.04 0.14 GATA6 0.82 0.76, 0.88 <0.001 NBN 0.97 0.81, 1.15 0.7 RAD51 1.18 1.01, 1.39 0.043 RECQL4 0.94 0.84, 1.04 0.2 Any RAS mutation 1.43 1.14, 1.81 0.002

103 Background: Clinicians spend significant time extracting and synthesizing information to risk-stratify and make adjuvant chemotherapy (AC) recommendations for CRC. By automating parts of this process, LLMs could help reduce documentation burden and variability in decision-making. Methods: We selected 144 stage III, pMMR CRC patients treated at Mayo Clinic (2017–2021). HIPAA-compliant Gemini-2.0-Flash-001 and GPT-4o extracted clinical variables (age, neuropathy grade, pathological stage) from EHRs and generated AC recommendations. Two approaches were compared: (1) a rule-based algorithm with nested if/else statements translating variables into NCCN-based recommendations, and (2) a dynamic LLM agent generating recommendations using a structured prompt informed by NCCN guidelines. Concordance with treating physicians was assessed, with disagreements reviewed by a blinded GI oncologist. Results: The dataset included 144 patients with median age 67 (IQR 66–68), 48.6% female. The LLM pipeline extracted neuropathy grade with 100% accuracy and pathological T/N stages with 99.3% accuracy. Concordance with physician recommendations was 93.1% for the rule-based algorithm and 62.5% for the LLM agent. In discordant cases, blinded adjudication by a GI oncologist favored the algorithm and LLM agent over physicians in most cases (Table 1). Conclusions: This exploratory work shows LLM agents can reliably extract variables and generate evidence-based treatment recommendations for stage III CRC. The high rate of expert preference for LLM recommendations in discordant cases is intriguing but limited by small sample size and possible adjudicator bias. Discordant physician recommendations reflect the complexity of decision-making, including patient preferences, performance status, comorbidities, and subtle findings not fully captured in EHRs. Rather than replacing judgment, we envision LLMs as decision support tools—analogous to an advanced trainee reviewing charts and presenting evidence-based recommendations to the attending physician with ultimate authority. Larger multi-institutional studies with multiple adjudicators are needed to validate these findings and clarify AI’s role in oncology. Patient characteristics, LLM extraction accuracy, and concordance with physician recommendations. Metric Result Total patients 144 Median age (IQR) 67 (66-68) Female (%) 48.6% LLM extraction accuracy – Neuropathy grade 100% LLM extraction accuracy – Pathological T and N stages 99.3% Primary Concordance – Rule-based algorithm vs. physician 93.1% Adjudicator preference of rule-based algorithm over treating physician for discordant cases 100% Concordance – LLM agent vs. physician 62.5% Adjudicator preference of LLM agent over treating physician for discordant cases 82.0%

Abstract Background The increased frequency of spinal surgeries has led to a rise in postoperative spine infections (PSIs), now recognized as the third most common surgical complication. Currently, there is no standardized definition of PSI, complicating clinical management and research. This meta-epidemiological study aimed to develop clear diagnostic criteria to assist clinicians and researchers in identifying and reporting PSIs consistently. 2020 PRISMA flow diagram Sankey diagram showing the distribution of combination of criteria or definitions used by the authors. This refers to 21 articles that used a definition derived by the authors. Methods Following PRISMA guidelines, a comprehensive literature search was conducted by a medical librarian using Ovid MEDLINE (March 14, 2024). Studies were included if they reported on at least ten adult patients diagnosed with PSI and provided clear diagnostic definitions. The primary objective was to evaluate existing PSI diagnostic criteria and categorize them into thematic clusters. We constructed standardized diagnostic combinations using 13 predefined criteria derived from clinical practice guidelines and prior research (Table 1).Characteristics of the included studies*Total can be more than 100% since some variables can be present in multiple categories.This refers to 21 articles that used a definition derived by the authors. For articles #411 and #630 categorization was not possible as the definition provided only information about the depth of infection and not the criteria for diagnosis. Article #1148 was included as, defining “presumed aspetic” cases meant, by definition, also defining infectious cases.Abbreviations. The American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP), Centers for Disease Control and Prevention (CDC), The National Healthcare Safety Network (NHSN), Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA), Magnetic Resonance Imaging (MRI) Results From an initial 1,466 studies screened, 101 were included (Figure 1). Most studies were retrospective (91/101, 92.1%), and a majority (77/101, 76.2%) relied on established criteria such as those from the American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) or the CDC. Seven studies combined predefined criteria with additional detailed explanations. Among the remaining studies using independent definitions, clinical signs and symptoms were the most common criteria (13/24, 54.2%) (Table 1). Criteria were grouped into clinical, microbiological, and radiological categories, with most studies primarily using clinical criteria alone or in combination with microbiological or imaging findings (Figure 2). Conclusion There was no clear consensus in the literature on what defines a PSI. Our findings emphasize the necessity of establishing a standardized PSI definition that integrates clinical, microbiological, and radiological criteria. Implementing such a unified framework could enhance diagnostic accuracy, address existing limitations associated with hardware complications, wound drainage interpretations, and imaging ambiguities, and improve upon the current shortcomings of surveillance systems. Disclosures Jeremy D. Shaw, MD, Globus: Grant/Research Support|Purgo Scientific: Advisor/Consultant|Purgo Scientific: Stocks/Bonds (Private Company)

Abstract Background In vivo biomarkers that can detect long‐term neuropathologies from repetitive head impact (RHI) exposure are needed, especially for the neurodegenerative tauopathy chronic traumatic encephalopathy (CTE). Here, we evaluated plasma p ‐tau217 as a potential biomarker for CTE p ‐tau pathology, and examined the concordance between plasma p ‐tau217 and Aβ pathology in an at‐risk for CTE sample. Method The sample included 180 male former football players (120 professional, 60 college), and 56 asymptomatic men without RHI (i.e., controls). Participants completed blood draws, 18F‐florbetapir (Aβ+=SUVR≥1.10), and 18F‐flortaucipir PET. Traumatic encephalopathy syndrome (TES) diagnoses were made. Single molecule array for plasma p ‐tau217 (ALZpath) was performed (≥0.6 cutoff used to maximize sensitivity). Nine participants had post‐mortem tissue. ANCOVA examined group differences in p ‐tau217 (football vs controls; TES‐CTE no, TES‐CTE suggestive, TES‐CTE possible/probable). Multivariable regression models tested associations between p ‐tau217 and florbetapir/flortaucipir PET. Covariates included age, race and APOE e4 . Result Sample characteristics are in Table 1. p ‐tau217 concentrations were higher in former football players compared to controls (est. marginal mean difference=‐0.217, p = 0.005). There were no group differences in Aβ‐PET SUVR. No differences were found across TES‐CTE certainty levels. In football players, higher p ‐tau217 was associated with higher Aβ‐PET SUVR (B=1.380, 95%CI[0.597‐2.155], p = 0.001) but not when Aβ+ ( n = 17) participants and those with kidney/liver disease ( n = 5) were excluded. Aβ+ participants had the highest p ‐tau217 (Figure 1). When compared against Aβ‐PET, several false Aβ‐positives (high p ‐tau217, Aβ‐) were identified, including one extreme outlier (assay related) and a cluster of Aβ‐ participants with p ‐tau217 between 0.60–1.0. There were no associations with flortaucipir SUVR (frontal, mesial temporal, left parietal). Two extreme p ‐tau217 outliers had autopsy‐confirmed CTE stage III (AD‐, Table 2). Of the remaining donors, all were AD‐ and four had CTE (stages II‐IV) with ptau217 between 0.125‐0.449. Conclusion Plasma p ‐tau217 has usefulness in quantifying Aβ pathology but restricted utility for detection of CTE. In this at‐risk for CTE sample, p ‐tau217 and Aβ‐PET were associated at the group level. At the individual level, false Aβ‐positives (and negatives) existed, including Aβ‐ participants with high p ‐tau217. We will explore whether this discrepancy is due to disease or peripheral interference with the N‐terminal binding in p ‐tau assays.

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 PET visual reads for multi‐center studies are conducted centrally by one or a few experts. In CLARiTI, a broader network of raters will perform the reads, necessitating methods to ensure their accuracy and reliability. Method All ADRC sites ( N = 37) will prospectively acquire amyloid PET scans for 800 cognitively unimpaired and 1200 cognitively impaired participants. Each site can use one of four amyloid PET tracers ([ 18 F]florbetaben, [ 18 F]florbetapir, [ 11 C]PIB, [ 18 F]NAV4694). PET scans will be visually interpreted by ten PET neuroimaging experts located across eight ADRCs, using their preferred hardware, software, and file format (DICOM, NIFTI). Calibration requires readers to perform blinded, independent visual interpretation of 180 amyloid PET scans (30 unique and 15 duplicate scans per tracer), previously read and selected by an expert (Table 1). An even mix of visually non‐elevated and elevated scans were selected, with quantitation spanning ‐26‐123 Centiloids (Figure 1), and 15% were visually borderline (similar proportion to ADNI4), with quantitation spanning 4‐48 Centiloids (mean 21). Kruskal‐Wallis H test showed no significant difference in the distribution of Centiloid values for scans in each tracer group, Χ 2 (3)=2.133, p = 0.545. Result Calibration scans were read by a second expert not serving in CLARiTI. There was 97% concordance and almost perfect agreement between readers (κ=0.932, p <0.001; Figure 2). Discordantly read scans were visually borderline elevated ( N = 2), borderline non‐elevated ( N = 1), and negative ( N = 1), with quantitation of 8‐21 Centiloids (mean 14). Intra‐rater reads were 98% concordant and had almost perfect agreement (κ=0.966, p <0.001). These findings hold promise for scaling‐up visual reads in CLARiTI, and we expect ≥80% concordance and substantial to almost perfect agreement (κ≥0.7) for inter/intra‐rater reliability. Conclusion Calibration is essential for accurate/reliable amyloid PET visual reads in large multi‐center studies with multiple raters. Through the calibration process, we will develop methods to improve the adjudication of borderline/challenging scans and formalize methods for visual reads of amyloid PET tracers that are investigational (i.e., [ 11 C]PIB, [ 18 F]NAV4694). Involving multiple raters across different sites, who use diverse hardware/software/file format combinations, will mirror the natural heterogeneity present in real‐world clinical practice. This calibration set can also serve as a standardized training tool for other studies incorporating amyloid PET visual reads.

Abstract Background Decreased kidney function, indicated by a lower estimated glomerular filtration rate (eGFR), may affect interpretation of Alzheimer's disease (AD) blood biomarkers, including phosphorylated tau ( p ‐tau) and amyloid‐beta (Aβ) peptides, due to altered clearance. However, there is limited data available to determine the influence of eGFR on these biomarkers and whether it differs by biomarker or assay type, especially in racially diverse studies of community‐based older adults. Methods We used data from 557 participants in the Mayo Clinic Study of Aging (Rochester, MN n = 182; age 79±8 years; 36.3% Female, White participants) and the UMMC MIND Center‐Mayo Clinic Study of Aging (Jackson, MS n = 375; age 69±8 years; 73% Female 27% Black participants). eGFR was determined using the 2021 CKD‐EPI Creatinine equation. Plasma biomarkers were measured using the Lumipulse immunoassays for p ‐tau217, Aβ42, and Aβ40 (Fujirebio Diagnostics; n = 420); or the mass spectrometry‐based PrecivityAD2 assay (C2N Diagnostics; n = 253) for p ‐tau217, np‐tau217, Aβ42, and Aβ40. Common ratio values were calculated. Aβ42/40 measures were inverted so higher values are worse for all biomarkers. Log base‐2 transformed regression analysis related eGFR to each single analyte and ratio; coefficients (95% CI) reflect estimated doubling in biomarker per doubling in eGFR. Group specific [MN White ( n = 182), MS White ( n = 224), MS Black ( n = 151) participants] estimates are reported, as the distribution of social determinants of health can vary across populations and locations. Results Lower eGFR was associated with higher (worse) AD‐plasma biomarkers, and group stratified estimates were mostly consistent (Figure 1). Ratios of biomarkers diminished but did not entirely alleviate associations with eGFR. For example, MN White participants’ C2N p ‐tau217 association of ‐1.47 (‐1.94, ‐1.00), was attenuated to ‐0.67 (‐1.11, ‐0.22), when using p ‐tau217/np‐tau217. Conclusions Kidney function may be associated with AD‐plasma biomarker values, even with common ratio corrections. There was not strong evidence for highly differential associations of eGFR by race/site categories, though sample sizes are currently limited. The implications for diagnosis and risk classification need to be explored further to support health equity. Optimal consideration of comorbidities on blood biomarker concentrations must continue to be informed by investigation in large, racially and ethnically diverse, community‐based studies.

Objective Dysautonomia affects many patients with Parkinson's disease and correlates with increased cardiovascular mortality. We describe the frequency and onset time of autonomic dysfunction relative to disease onset in early‐onset Parkinson's disease (EOPD) and explore its association with mortality. Methods We identified all incident Parkinson cases with motor‐symptom onset before age 50 years evaluated at the Mayo Clinic Health System (1990–2022) including sex‐ and age‐matched controls for each patient. Medical record review confirmed clinical diagnosis and assessed the presence and onset of autonomic symptoms, relative to Parkinson onset. Results We included 829 patients with EOPD and 829 healthy controls. The median age at disease onset was 42 years (interquartile range [IQR] = 37–46 years). Autonomic symptoms were present in 63.4% of patients, compared with 27.0% of unaffected controls, and proceeded motor symptoms in 91.4%. Forty‐seven percent of patients with early‐onset Parkinson's disease had constipation, 27.4% had bladder urgency, 19.3% had orthostatic intolerance, and 15.4% had sweat dysfunction. Among male patients, 36.8% had erectile dysfunction. In our EOPD population only, the presence of any autonomic‐impairment symptoms correlated with a 2.71‐fold increased mortality risk; each additional reported symptom increased the relative mortality risk by 50% ( p < 0.001). Patients with constipation or orthostatic intolerance had a 3.22‐ and 2.78‐fold higher mortality than patients without these symptoms. Interpretation Autonomic impairment affects 63.4% of patients with EOPD and carries a 3‐fold higher mortality risk, which increases with every additional autonomic symptom reported. In our cohort, autonomic symptoms appeared most commonly after motor onset, contrasting with prodromal autonomic impairment seen in late‐onset Parkinson's disease (LOPD). ANN NEUROL 2026;99:964–975