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Abstract Background Molecular underpinnings and clinical characteristics of ERBB2/HER2-mutated colorectal cancers (CRCs) remain poorly understood. We aimed to comprehensively characterize the genomic landscape and clinical features of ERBB2/HER2-mutated CRC and to compare them with those of ERBB2/HER2-amplified CRC. Patients and methods We analyzed cBioPortal data from 4348 CRC patients with available ERBB2/HER2 profiling. Clinicodemographic features, microsatellite instability (MSI), tumor mutational burden, and alterations in 94 cancer-associated genes were evaluated using chi-square/Fisher’s exact test, Kruskal–Wallis test, and hierarchical clustering. Results ERBB2/HER2 putative driver mutations were identified in 95 patients (2.2%), amplifications in 87 (2.0%), and wild-type status in 4166 (95.8%). In the overall cohort, ERBB2/HER2-mutated tumors demonstrated significant KRAS enrichment (50.5%) compared to wild-type (37.7%; P = .014) and amplified tumors (18.4%; P < .001), alongside MSI enrichment (37.2% vs 1.6%; P < .001), elevated tumor mutational burden, and right-sided predominance. ERBB2/HER2-mutated tumors also showed broad driver co-alterations largely reflecting their MSI background. In contrast, ERBB2/HER2-amplified tumors exhibited left-sided predominance, with microsatellite stable (MSS)-restricted analyses revealing selective mutual exclusivity with KRAS (Log2 OR = −1.58; q = 0.019) and TP53 co-occurrence (Log2 OR = 2.04; q = 0.019). Hierarchical clustering confirmed that mutated and amplified tumors consistently occupy separate clusters across anatomical sites. Conclusion ERBB2/HER2 mutations and amplifications represent molecularly and clinically distinct subgroups. ERBB2/HER2-mutated tumors are characterized by an MSI-enriched, hypermutated background with frequent concurrent KRAS alterations, whereas amplified tumors exhibit selective KRAS mutual exclusivity and TP53 co-occurrence. These exploratory findings support alteration-specific therapeutic strategies in CRC.

Importance Elevated low-density lipoprotein cholesterol (LDL-C) is a modifiable risk factor for cardiovascular disease, the leading cause of premature death worldwide. Assessing the LDL-C–related burden is critical for guiding prevention and treatment strategies. Objectives To estimate the global, regional, and national burden of ischemic heart disease and ischemic stroke attributable to elevated LDL-C (relative to 35-54 mg/dL) from 1990 to 2023 and to quantify the contributions of population growth, aging, risk-deleted burden, and exposure changes to burden trends. Design, Setting, and Population This comparative risk assessment, part of the Global Burden of Disease Study 2023, estimated population-level LDL-C exposure and associated health loss in 204 countries and territories. Mean LDL-C levels were estimated using spatiotemporal gaussian process regression based on 806 studies across 161 countries. Relative risks were derived from meta-analyses of 38 randomized clinical trials. Population-attributable fractions for deaths and disability-adjusted life-years (DALYs) were estimated by age and sex for adults aged 25 years or older from 1990 to 2023, with 95% uncertainty intervals. Exposure Population-level LDL-C concentrations. Main Outcomes and Measures Population-attributable fractions, counts, and rates (all ages and age standardized per 100 000) of LDL-C–attributable deaths and DALYs from ischemic heart disease and ischemic stroke, with uncertainty intervals. Results In 2023, elevated LDL-C accounted for 3.6 million deaths (95% uncertainty interval, 2.2-5.4 million; 6.0% of global mortality) and 90.7 million DALYs (95% uncertainty interval, 58.9-123.3 million; 3.2% of DALYs). Although global all-ages rates remained stable, age-standardized death and DALY rates decreased by 45.6% and 39.5%, respectively, since 1990. In 2023, age-standardized LDL-C–attributable DALY rates were highest in Eastern Europe and lowest in high-income Asia-Pacific. One-third of the global LDL-C burden occurred in India and China. Population growth and aging drove the increasing burden, with notable regional disparities in LDL-C exposure and risk-deleted DALY rates shifting toward middle-sociodemographic settings. Conclusions and Relevance Despite declining age-standardized rates, the absolute LDL-C burden has increased since 1990 due to demographic changes and has shifted toward middle-sociodemographic countries. Measurement and surveillance gaps persist. Strengthened prevention, diagnosis, and treatment access strategies are essential to mitigate the health burden of LDL-C.

Abstract Background Identification of individuals at increased risk for synucleinopathies is becoming more feasible with advances in biomarkers. However, the ethical and practical aspects of communicating disease risk remain unresolved, particularly across diagnostic groups and cultural contexts. Objectives We aimed to evaluate attitudes toward disclosure of future synucleinopathy risk among individuals with isolated/idiopathic REM sleep behavior disorder (iRBD), as well as in individuals who developed Parkinson's disease (PD), or multiple system atrophy (MSA), in a large non‐Western registry. Methods This nationwide survey study included participants from 28 movement disorders and sleep centers across Türkiye. Questionnaires assessing attitudes toward risk disclosure, additional testing, and clinical trial participation were administered face‐to‐face. Responses were analyzed using contingency tables and regression models. Results are reported following the Consensus‐Based Checklist for Reporting of Survey Studies (CROSS) guideline. Results Among 1385 participants (1039 PD, 107 MSA, 239 iRBD), individuals with iRBD showed the highest support for risk disclosure (88.3%), exceeding PD (64.4%) and MSA (51.9%). Approval declined modestly (3–8%) when framed within the absence of disease‐modifying treatment. iRBD participants were more willing for additional testing but less willing to join clinical trials (31.8%) than PD (45.3%) or MSA (48%). MSA patients expressed the greatest concern about psychological impact. Male sex had more favorable views on disclosure and trial participation, while younger and better‐educated participants favored additional testing. Conclusions Attitudes toward risk disclosure differ markedly across the synucleinopathy spectrum and demographic characteristics. Culturally informed and diagnosis‐specific disclosure strategies will be essential for trial recruitment and patient‐centered care.

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.

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.

e16486 Background: Allele-specific KRAS G12C inhibitors have revolutionized lung and colorectal cancer treatment, yet the biology of G12C in other gastrointestinal (GI) malignancies remains undefined. We aimed to elucidate the clinicopathologic and genomic landscape of KRAS G12C-mutated tumors compared to other G12 variants in a large non-colorectal GI cohort. Methods: We queried cBioPortal for pancreatic, esophagogastric, hepatobiliary, ampullary, and appendiceal adenocarcinomas. Following data quality control, the final cohort (n = 6,352) was stratified into KRAS wild-type (n = 3,293), G12C (n = 63), and other G12 variants (n = 2,996). Clinicopathologic features, tumor mutational burden (TMB), microsatellite instability status, and co-alteration in 96 key genes across 11 signaling pathways were compared. Statistical significance was assessed using Fisher’s exact or Chi-square tests for categorical variables and Kruskal-Wallis tests for continuous variables. The Benjamini-Hochberg method was applied to correct for multiple hypothesis testing. Results: KRAS G12C prevalence was 1.0% overall, with significant heterogeneity across cancer subtypes (p < 0.001). Appendiceal adenocarcinoma demonstrated the highest G12C prevalence at 5.71% (10/175), followed by ampullary (1.44%, 2/139), pancreatic (1.17%, 34/2906), hepatobiliary (0.88%, 12/1360), and esophagogastric cancers (0.28%, 5/1772). G12C patients were significantly older than wild-type patients (64.8±11.2 vs 62.5±12.9 years, mean±SD, p < 0.001) but younger than other G12 variant carriers (65.8±10.4 years). G12C tumors demonstrated intermediate genomic instability, with a TMB of 4.82±6.17 compared to 4.98±10.55 in wild-type tumors and 3.67±10.12 in other G12 variants (p < 0.001). Notably, G12C tumors were universally microsatellite stable (0% MSI-H vs 4.0% wild-type vs 0.9% other G12, p < 0.001). Genomic analysis revealed that AKT1 mutations were significantly enriched in the G12C cohort (6.3% vs 0.4%; q = 0.025) as compared to other G12 variants. A trend of increased mutation frequency in HRAS was observed specifically in pancreatic cancers in G12C tumors as compared to other variants (8.8% vs 0.7%; q = 0.083). In pancreatic adenocarcinoma, G12C tumors were enriched for chromatin modifiers, notably ARID1A (17.6% vs 7.7%, p = 0.045) and SETD2 / SETD26 (8.8% vs 1.1%, p = 0.006), though these did not reach FDR significance. Notably, the immunotherapy-resistance drivers STK11 and KEAP1 were absent (0%) in the whole G12C cohort. Conclusions: KRAS G12C represents a biologically distinct subgroup of exon 2 KRAS mutations compared to other KRAS G12 pathogenic variants. The absence of resistance markers and enrichment of actionable AKT1 and chromatin-modifier mutations suggest distinct therapeutic vulnerabilities in non-colorectal KRAS G12C-mutated GI cancers.

Abstract Background: Mantle cell lymphoma (MCL) is an aggressive and rare B-cell non-Hodgkin lymphoma with poor prognosis, even with treatment. Despite its clinical importance, the etiology of MCL remains largely unknown. Some studies have reported a positive association with family history, suggesting that genetic factors could contribute to risk. Methods: To identify germline genetic variants associated with risk, we conducted the first genome-wide association studies (GWAS) and GWAS meta-analysis for MCL, comprising 1,163 cases and 61,271 controls. The most significant loci were taken forward for replication in three independent studies, including 576 cases and 771,773 controls. To identify potential target genes and pathways of discovered loci, we conducted F-MAGMA, colocalization, and transcriptome-wide association study (TWAS) analyses. To gain insight into underlying regulatory mechanisms, we performed integrative epigenomic analyses using DNase I hotspots and histone mark ChIP-seq data across diverse cell types applying the FORGE2 framework. Results: In the joint analyses, we identified eight genome-wide significant loci (P&lt;5x10-8) associated with MCL risk, several of which were located near genes with known DNA repair (ATM), telomere (TERT), or RNA-binding functions (RBM20). Further analyses using F-MAGMA, which uses DNase-seq data to prioritize genes from GWAS, identified genes that were significantly associated with risk, including SP140, a chromatin reader and immune regulator of pathogen response. This gene also displayed strong colocalization with our lead variant in whole blood (COLOC posterior probability PP4=0.97). TWAS demonstrated significant associations with SP140 and ACTA2, which has been linked to cell proliferation (P&lt;3x10-6). Enrichment for DNase I hotspots was observed in B and T lymphocytes (q-value&lt;0.05), providing evidence for a role in immune cell-specific regulatory regions. Enrichment for enhancer-associated histone mark H3K4me1 was observed in B cells (q-value&lt;0.01), highlighting a role for immune cell-specific enhancers. Transcription factor (TF) motif enrichment analysis pointed to TFs critical for B-cell development and differentiation, notably TCF3 and EP300 (q&lt;0.01 for both), suggesting an association between B-cell lineage regulation and MCL risk. Finally, genome-wide SNP-based heritability was estimated to be 17%, underscoring the importance of common variants in MCL risk. Conclusion: Our study provides novel insight into the inherited susceptibility of MCL by identifying eight significant loci and estimating substantial common variant heritability. These findings highlight a role for several distinct biological pathways -specifically DNA repair, telomerase function, and B-cell differentiation- in the etiology of MCL, offering new targets for mechanistic investigation. Citation Format: Charles E. Breeze, Alyssa Clay-Gilmour, Hanla A. Park, Ólafur B. Davíðsson, Angelica Macauda, Brenda M. Birmann, Elizabeth E. Brown, Murat Güler, Michelle A. T. Hildebrandt, Alexandra Nieters, Krystle Ong, Jojo Biel-Nielsen Dietz, Karin E. Smedby, Karl Smith-Byrne, Rosalie Griffin, Sophia S. Wang, Susan Slager, James R. Cerhan, Jonathan N. Hofmann, Qing Lan, Nathaniel Rothman, Ingrid Glimelius, Henrik Hjalgrim, James Mckay, Sonja I. Berndt. Genome-wide association study of mantle cell lymphoma identifies novel loci suggesting a critical role for B-cell chromatin readers and DNA repair mechanisms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3602.

Abstract Monoclonal gammopathy of undetermined significance (MGUS) is a necessary precursor condition to multiple myeloma (MM). Given the role of autophagy in modulating MM risk, we investigated whether genetic variation in autophagy‐related genes influences susceptibility to MGUS. We analyzed the association of 34,042 common autophagy‐related single nucleotide polymorphisms (SNPs) with MGUS across six independent cohorts, five from Europe and one from North America, comprising 2317 MGUS cases and 282,358 controls. We also assessed their impact on immune parameters, including absolute counts of 91 blood‐derived immune cell subsets and 103 circulating immunological proteins. Meta‐analysis revealed a genome‐wide significant association between the ULK4 rs6599175C allele and increased MGUS risk ( p = 3.35 × 10 −8 ). Carriers of this allele showed reduced counts of memory B cell subsets (IgM+CD38+CD27+ and IgD+IgM+CD27+; p = .0038 and p = .0056, respectively) and natural effector B cells (CD24+CD38+IgD+IgM+ cells; p = .0060). Although these associations were not statistically significant after multiple testing correction, they suggest a role of ULK4 in early B‐cell differentiation. Additionally, the CDKN2A rs2811710 variant showed a suggestive association with MGUS risk ( p = 2.17 × 10 −4 ), affecting transcription factor binding involved in B‐cell proliferation and differentiation, although it lacked association with immune markers. In conclusion, we confirm a genome‐wide significant association of the ULK4 locus and MGUS risk, supporting its role in early B‐cell differentiation, and identify CDKN2A as a candidate susceptibility locus warranting further investigation.

Abstract Background Intracranial mesenchymal tumors, FET::CREB fusion-positive (ICMT), show fusions involving FET RNA-binding protein family genes (EWSR1 or FUS) and CREB family of transcription factors (ATF1, CREB1, or CREM). The methylation signature(s), gene expression characteristics, and clinical behavior of this important tumor type require further characterization. Methods We study the methylation profiles of 81 ICMT cases (61 newly profiled cases and 20 cases from publicly available sources). Clinicopathologic and genomic data were recorded for each case when available. Results ICMT showed a relatively distinct methylation signature compared to related tumors. Among the 65 cases where fusion types were documented, the identified fusions included EWSR1::ATF1 (25 cases), EWSR1::CREB1 (12 cases), EWSR1::CREM (21 cases), FUS::CREM (3 cases), and SMARCA2::CREM (4 cases). We confirmed the prior description of 2 distinct subgroups of ICMT (subclasses A and B). The majority of the cases belonged to subclass A (n = 69; 85%), which showed a higher median age compared to subclass B patients (26 years vs. 15 years). Subclass B cases (n = 12; 15%) showed shorter progression-free survival (P &lt; 0.01). Gene expression analysis of ICMT showed key overexpressed markers in ICMT, with significant CREM overexpression regardless of fusion type, when compared to either meningioma alone or a larger group of CNS tumors. Conclusions This work provides further characterization of ICMT as an important CNS mesenchymal neoplasm that is prone to tumor recurrence, showing 2 prognostically relevant methylation subclasses and warranting diagnostic distinction from other epigenetically and histologically related tumors. ICMTs show substantial overexpression of the CREM gene, independent of fusion type.

210 Background: ERBB2/HER2 amplification defines a rare but clinically distinct subtype of colorectal cancer (CRC), associated with favorable responses to HER2-targeted therapies. In contrast, ERBB2/HER2 -mutant CRCs show limited therapeutic benefit, and their clinical and molecular features remain poorly defined. This study investigated the molecular and clinical features of ERBB2/HER2 -mutant CRCs to provide insight into the molecular basis of their differential therapeutic vulnerabilities compared to amplified CRC. Methods: CRC cases were identified from cBioPortal studies with available clinical and ERBB2/HER2 genomic data. After quality control and deduplication, the cohort included 4407 unique cases: 97 with driver mutation(s) only (2.2%), 86 with amplification only (2%), and 4224 wild-type (95.9%). Demographic, clinical, and molecular features, including microsatellite instability (MSI), tumor mutational burden (TMB), and alterations in 94 oncogenic pathway genes, were compared across groups. Statistical analyses used chi-square/Fisher’s exact tests for categorical data, Kruskal-Wallis tests for continuous variables, and the Benjamini-Hochberg correction for multiple comparisons. Odds ratios and FDR-adjusted p-values were calculated to assess associations. Results: Across groups, the distributions of gender, race, and primary cancer site (colon or rectal cancer) were comparable. However, significant differences were observed in age (mean 58.7 ± 15.0 years for ERBB2/HER2 -mutant, 55 ± 13.9 for amplified, and 59 ± 14.8 for wild-type; p = 0.035) and tumor sidedness (among ERBB2/HER2 -mutant cases: right-colon 30.8%, left-colon 15.2%; among ERBB2/HER2 -amplified: right-colon 12.1%, left-colon 37.9%, p = 0.011). KRAS alterations were significantly more common in ERBB2/HER2 -mutant CRCs (50.5%) compared with both amplified (19.8%) and wild-type (37.6%). MSI-H was detected in 34.5% of ERBB2/HER2 -mutant cases, whereas no MSI-H was observed among amplified tumors (p < 0.001). Expectedly, ERBB2/HER2 -mutant tumors exhibited a hypermutated phenotype, with significantly higher TMB (30.3 ± 45.5) and total mutation count (232.8 ± 926.0), compared to amplified (6.1 ± 9.7 and 15.3 ± 28.4) and wild-type (10.5 ± 20.3 and 126.3 ± 424.5; both p < 0.001). Conversely, ERBB2/HER2 -amplified tumors had the highest fraction of overall genomic alterations including chromosomal changes (0.24 ± 0.17 in amplified vs 0.14 ± 0.17 in mutants and 0.20 ± 0.16 in wild-type; p < 0.001). Hierarchical clustering demonstrated that ERBB2/HER2 -mutant tumors form a distinct molecular cluster, whereas amplified tumors cluster closely with wild-type CRC. Conclusions: ERBB2/HER2 - mutant and amplified CRCs show highly distinct genomic and clinical features, supporting the need for tailored treatment approaches.