Decoding changes in tumor-infiltrating leukocytes through dynamic experimental models and single-cell technologies.

The ability to characterize immune cells and explore the molecular interactions that govern their functions has never been greater, fueled in recent years by the revolutionary advance of single-cell analysis platforms. However, precisely how immune cells respond to different stimuli and where differentiation processes and effector functions operate remain incompletely understood. Inferring cellular fate within single-cell transcriptomic analyses is now omnipresent, despite the assumptions typically required in such analyses. Recently developed experimental models support dynamic analyses of the immune response, providing insights into the temporal changes that occur within cells and the tissues in which such transitions occur. Here we will review these approaches and discuss how these can be combined with single-cell technologies to develop a deeper understanding of the immune responses that should support the development of better therapeutic options for patients.

Responses to Basal Insulin Glargine (300 U/mL and 100 U/mL) with or Without Pre-prandial Insulin in Pre-treated Subphenotypes of Type 2 Diabetes: Insights from a Post Hoc Analysis.

INTRODUCTION: This study aimed to evaluate glycemic outcomes in subphenotypes of type 2 diabetes (T2D) with HbA1c > 7.0%, previously on basal insulin (pre-BI) alone (≥ 42 U/day) or on basal-bolus therapy (pre-BB), and who were switched to either basal insulin glargine 300 U/mL (IGlar-300) or 100 U/mL (IGlar-100), with or without pre-prandial insulin. METHODS: Participants from EDITION 2 (pre-BI, n = 785), and EDITION 1 (pre-BB, n = 792) trials were assigned retrospectively to subphenotypes of T2D: severe insulin deficient diabetes (SIDD), mild age-related diabetes (MARD), mild obesity diabetes (MOD), and severe insulin resistant diabetes (SIRD). Key efficacy and safety parameters were analyzed at baseline, and after 26 weeks, for IGlar-300 and IGlar-100 pooled groups according to subphenotypes. Outcomes were also compared with insulin-naïve subphenotypes on oral antihyperglycemic drugs (OADs) from the EDITION 3 trial (pre-OAD, n = 858). RESULTS: Pre-BI and pre-BB treated subphenotypes with SIDD had a higher mean HbA1c (8.9% and 9.1%) at baseline compared to those of MARD (7.7% and 7.8%) and MOD (8.1% and 8.2%) and after 26 weeks remained above target HbA1c (7.7% and 8.0%) despite mean glargine doses of 0.7 to 1.0 U/kg/day and pre-prandial insulin use in the pre-BB SIDD subgroup. Pre-BB treated individuals with MARD and MOD achieved lower HbA1c levels (6.9% and 7.2%) than the pre-BI groups (7.3% and 7.5%) despite similar mean FPG levels (123-130 mg/dL). Only 19-22% of participants with SIDD achieved HbA1c < 7.0% compared to 33-51% with MARD and MOD, respectively. Pre-BI and pre-BB treated subphenotypes experienced more hypoglycemia than pre-OAD treated subphenotypes. CONCLUSION: Individuals with T2D assigned post hoc to the SIDD subphenotype achieved suboptimal glycemic control with glargine regimens including basal-bolus therapy, alerting clinicians to improve further diabetes treatment, particularly post-prandial glycemic control, in individuals with SIDD.

Chromosome-level genome assemblies of 2 hemichordates provide new insights into deuterostome origin and chromosome evolution.

Deuterostomes are a monophyletic group of animals that includes Hemichordata, Echinodermata (together called Ambulacraria), and Chordata. The diversity of deuterostome body plans has made it challenging to reconstruct their ancestral condition and to decipher the genetic changes that drove the diversification of deuterostome lineages. Here, we generate chromosome-level genome assemblies of 2 hemichordate species, Ptychodera flava and Schizocardium californicum, and use comparative genomic approaches to infer the chromosomal architecture of the deuterostome common ancestor and delineate lineage-specific chromosomal modifications. We show that hemichordate chromosomes (1N = 23) exhibit remarkable chromosome-scale macrosynteny when compared to other deuterostomes and can be derived from 24 deuterostome ancestral linkage groups (ALGs). These deuterostome ALGs in turn match previously inferred bilaterian ALGs, consistent with a relatively short transition from the last common bilaterian ancestor to the origin of deuterostomes. Based on this deuterostome ALG complement, we deduced chromosomal rearrangement events that occurred in different lineages. For example, a fusion-with-mixing event produced an Ambulacraria-specific ALG that subsequently split into 2 chromosomes in extant hemichordates, while this homologous ALG further fused with another chromosome in sea urchins. Orthologous genes distributed in these rearranged chromosomes are enriched for functions in various developmental processes. We found that the deeply conserved Hox clusters are located in highly rearranged chromosomes and that maintenance of the clusters are likely due to lower densities of transposable elements within the clusters. We also provide evidence that the deuterostome-specific pharyngeal gene cluster was established via the combination of 3 pre-assembled microsyntenic blocks. We suggest that since chromosomal rearrangement events and formation of new gene clusters may change the regulatory controls of developmental genes, these events may have contributed to the evolution of diverse body plans among deuterostomes.

Long non-coding RNA TUG1 is downregulated in Friedreich's ataxia.

Friedreich's ataxia is a neurodegenerative disorder caused by reduced frataxin levels. It leads to motor and sensory impairments and has a median life expectancy of around 35 years. As the most common inherited form of ataxia, Friedreich's ataxia lacks reliable, non-invasive biomarkers, prolonging and inflating the cost of clinical trials. This study proposes TUG1, a long non-coding RNA, as a promising blood-based biomarker for Friedreich's ataxia, which is known to regulate various cellular processes. In a previous study using a frataxin knockdown mouse model, we observed several hallmark Friedreich's ataxia symptoms. Building on this, we hypothesized that a dual-source approach-comparing the data from peripheral blood samples from Friedreich's ataxia patients with tissue samples from affected areas in Friedreich's ataxia knockdown mice, tissues usually unattainable from patients-would effectively identify robust biomarkers. A comprehensive reanalysis was conducted on gene expression data from 183 age- and sex-matched peripheral blood samples of Friedreich's ataxia patients, carriers and controls and 192 tissue data sets from Friedreich's ataxia knockdown mice. Blood and tissue samples underwent RNA isolation and quantitative reverse transcription polymerase chain reaction, and frataxin knockdown was confirmed through enzyme-linked immunosorbent assays. Tug1 RNA interaction was explored via RNA pull-down assays. Validation was performed in serum samples on an independent set of 45 controls and 45 Friedreich's ataxia patients and in blood samples from 66 heterozygous carriers and 72 Friedreich's ataxia patients. Tug1 and Slc40a1 emerged as potential blood-based biomarkers, confirmed in the Friedreich's ataxia knockdown mouse model (one-way ANOVA, P ≤ 0.05). Tug1 was consistently downregulated after Fxn knockdown and correlated strongly with Fxn levels (R 2 = 0.71 during depletion, R 2 = 0.74 during rescue). Slc40a1 showed a similar but tissue-specific pattern. Further validation of Tug1's downstream targets strengthened its biomarker candidacy. In additional human samples, TUG1 levels were significantly downregulated in both whole blood and serum of Friedreich's ataxia patients compared with controls (Wilcoxon signed-rank test, P < 0.05). Regression analyses revealed a negative correlation between TUG1 fold-change and disease onset (P < 0.0037) and positive correlations with disease duration and functional disability stage score (P < 0.04). This suggests that elevated TUG1 levels correlate with earlier onset and more severe cases. This study identifies TUG1 as a potential blood-based biomarker for Friedreich's ataxia, showing consistent expression variance in human and mouse tissues related to disease severity and key Friedreich's ataxia pathways. It correlates with frataxin levels, indicating its promise as an early, non-invasive marker. TUG1 holds potential for Friedreich's ataxia monitoring and therapeutic development, meriting additional research.

Updated cutaneous T-cell lymphoma TNMB staging criteria fail to identify Sézary syndrome patients with low blood burden.

Comparison of the 2007 EORTC/ISCL and the 2022 EORTC/ISCL/USCLC blood staging guidelines for cutaneous T-cell lymphoma at a single institution reveals the newer guidelines fail to detect a subset of Sézary syndrome patients with low blood burden.

Use of Vaccines in Patients Receiving Dupilumab, A Systematic Review and Expert Delphi Consensus Recommendation: A position paper of the American College of Allergy, Asthma and Immunology.

BACKGROUND: Dupilumab is a monoclonal antibody targeting the interleukin (IL)-4 receptor alpha subunit, thus blocking the effects of IL-4 and IL-13, and has shown efficacy in treating various conditions including asthma, atopic dermatitis, eosinophilic esophagitis, and others. Due to its immune modulatory effects, clinical trials studying dupilumab did not allow for patients to receive live vaccines during the clinical trials out of an abundance of caution, and thus package insert recommends patients being treated with dupilumab avoid live vaccines. As dupilumab is now approved down to 6 months of age for the treatment of atopic dermatitis, this reported contraindication is now posing a clinical dilemma for patients and clinicians. OBJECTIVE: To perform a systematic review of literature on the safety and efficacy of vaccinations in patients receiving dupilumab and to provide expert guidance on the use of vaccines in patients receiving dupilumab. METHODS: A systematic review of the literature was performed, and an expert Delphi Panel was conducted. RESULTS: The available literature on patients who received vaccinations while on dupilumab overall suggests that live vaccines are safe and the vaccine efficacy, in general, is not affected by dupilumab. The expert Delphi panel agreed on the use of vaccines in patients on dupilumab was likely safe and effective. CONCLUSION: Vaccines (including live vaccines) can be administered to patients on dupilumab in a shared decision-making capacity.

Addressing Diagnostic Gaps and Priorities of the Global Rare Diseases Community: Recommendations from the IRDiRC Diagnostics Scientific Committee.

The International Rare Diseases Research Consortium (IRDiRC) Diagnostic Scientific Committee (DSC) is charged with discussion and contribution to progress on diagnostic aspects of the IRDiRC core mission. Specifically, IRDiRC goals include timely diagnosis, use of globally coordinated diagnostic pipelines, and assessing the impact of rare diseases on affected individuals. As part of this mission, the DSC endeavored to create a list of research priorities to achieve these goals. We present a discussion of those priorities along with aspects of current, global rare disease needs and opportunities that support our prioritization. In support of this discussion, we also provide clinical vignettes illustrating real-world examples of diagnostic challenges.

Deep mutational scanning quantifies DNA binding and predicts clinical outcomes of PAX6 variants.

Nonsense and missense mutations in the transcription factor PAX6 cause a wide range of eye development defects, including aniridia, microphthalmia and coloboma. To understand how changes of PAX6:DNA binding cause these phenotypes, we combined saturation mutagenesis of the paired domain of PAX6 with a yeast one-hybrid (Y1H) assay in which expression of a PAX6-GAL4 fusion gene drives antibiotic resistance. We quantified binding of more than 2700 single amino-acid variants to two DNA sequence elements. Mutations in DNA-facing residues of the N-terminal subdomain and linker region were most detrimental, as were mutations to prolines and to negatively charged residues. Many variants caused sequence-specific molecular gain-of-function effects, including variants in position 71 that increased binding to the LE9 enhancer but decreased binding to a SELEX-derived binding site. In the absence of antibiotic selection, variants that retained DNA binding slowed yeast growth, likely because such variants perturbed the yeast transcriptome. Benchmarking against known patient variants and applying ACMG/AMP guidelines to variant classification, we obtained supporting-to-moderate evidence that 977 variants are likely pathogenic and 1306 are likely benign. Our analysis shows that most pathogenic mutations in the paired domain of PAX6 can be explained simply by the effects of these mutations on PAX6:DNA association, and establishes Y1H as a generalisable assay for the interpretation of variant effects in transcription factors.

The effect of factors from different time points on psychological readiness following ACL reconstruction.

OBJECTIVE: The purpose of this study was to examine factors correlated with psychological readiness to return to activity after ACLR. DESIGN: cross sectional study. SETTING: controlled laboratory. PARTICIPANTS: 164 patients (82 M/82 F, 22.5 ± 8.9yr, 171.6 ± 11.0 cm, 77.4 ± 18.6 kg, 8.6 ± 3.4 months post-ACLR) participated in this study after a primary, isolated, and uncomplicated ACLR. MAIN OUTCOME MEASURES: ACL Return to Sport Index (ACL-RSI). RESULTS: ACL-RSI scores demonstrated a weak positive correlation with activity level at the time of injury and a fair positive correlation with activity level at the time of post-operative testing (p-values: 0.004, <0.001). ACL-RSI scores showed a statistically significant fair negative correlation with pain and a moderate negative correlation with kinesiophobia during rehabilitation (p-values: <0.001, <0.001). There was no statistical significance between ACL-RSI and the surgical variables (p-value range: 0.10-0.61). CONCLUSIONS: Outcomes from testing during postoperative rehabilitation were most correlated with psychological readiness to return to activity after ACLR. Increased pain and kinesiophobia were associated with a decreased psychological readiness. Increased activity level prior to injury and activity level at the time of testing during rehabilitation were both correlated with increased psychological readiness. Psychological readiness to return to activity may need to be customized based on potentially modifiable patient-specific factors during the post-operative rehabilitation.

A typology of internationally qualified dentists in the United Kingdom.

Introduction: The Global Strategy for Human Resources for Health 2030, requires member states to half their dependency on an international workforce by 2030. In order to design policies towards that goal, country-specific research on migration motivations of the health workforce is required. The United Kingdom (UK) is a net importer of health professionals and whilst there is a body of research on doctors' and nurses' migration, there is no research on the migration motivations of migrant dentists in the UK. This research explored the migration motivations of internationally qualified dentists (IQDs) in the UK and presents a typology to understand the global migration of dentists in the context of oral health workforce. Methods: The paper presents qualitative data from semi-structured interviews conducted between August 2014 and October 2017, of IQDs working in the United Kingdom. The topic guide for interviews was informed by the literature, with new themes added inductively. A phenomenological approach involving an epistemological stance of interpretivism, was used with framework analysis. Results: A total of 38 internationally qualified dentists (M = 18, F = 20), migrating from the five World Health Organization regions, and working in general practice, NHS hospitals and in community dental services across the four nations of the UK were interviewed. Seven types of internationally qualified dentists were identified working in the UK. They were livelihood migrants, career-orientated migrants, dependant migrants, backpacker migrants, commuter migrants, undocumented migrants, and education-tourist migrant. The categories were based on their migration motivations, which were complex, multifactorial, and included personal, professional, national, and international drivers. The typology, based on their migration motivations, offered a structured, comprehensive understanding of the migrant dental workforce. This typology involving dentists provides additional dimensions to commuter and undocumented migrants described in the context of other health professionals. The education-tourist migrant is a new category proposed as an extension to existing typology in health professional migration. Conclusions: The typology of internationally qualified dentists has congruency with other health professionals' typology in categories previously described and demonstrates that each of these categories are complex, fluid and change in response to policy changes. The new category of education-tourist migrant along with oral health dimensions of commuter and undocumented migrants adds to the existing typology in health professional migration.

Making assessment a team sport: a qualitative study of facilitated group feedback in internal medicine residency.

Purpose: Competency-based medical education relies on feedback from workplace-based assessment (WBA) to direct learning. Unfortunately, WBAs often lack rich narrative feedback and show bias towards Medical Expert aspects of care. Building on research examining interactive assessment approaches, the Queen's University Internal Medicine residency program introduced a facilitated, team-based assessment initiative ("Feedback Fridays") in July 2017, aimed at improving holistic assessment of resident performance on the inpatient medicine teaching units. In this study, we aim to explore how Feedback Fridays contributed to formative assessment of Internal Medicine residents within our current model of competency-based training. Method: A total of 53 residents participated in facilitated, biweekly group assessment sessions during the 2017 and 2018 academic year. Each session was a 30-minute facilitated assessment discussion done with one inpatient team, which included medical students, residents, and their supervising attending. Feedback from the discussion was collected, summarized, and documented in narrative form in electronic WBA forms by the program's assessment officer for the residents. For research purposes, verbatim transcripts of feedback sessions were analyzed thematically. Results: The researchers identified four major themes for feedback: communication, intra- and inter-personal awareness, leadership and teamwork, and learning opportunities. Although feedback related to a broad range of activities, it showed strong emphasis on competencies within the intrinsic CanMEDS roles. Additionally, a clear formative focus in the feedback was another important finding. Conclusions: The introduction of facilitated team-based assessment in the Queen's Internal Medicine program filled an important gap in WBA by providing learners with detailed feedback across all CanMEDS roles and by providing constructive recommendations for identified areas for improvement.

Objectif: La formation médicale fondée sur les compétences s'appuie sur la rétroaction faite lors de l'évaluation des apprentissages par observation directe dans le milieu de travail. Malheureusement, les évaluations dans le milieu de travail omettent souvent de fournir une rétroaction narrative exhaustive et privilégient les aspects des soins relevant de l'expertise médicale. En se basant sur la recherche ayant étudié les approches d'évaluation interactive, le programme de résidence en médecine interne de l'Université Queen's a introduit en juillet 2017 une initiative d'évaluation facilitée et en équipe (« Les vendredis rétroaction ¼), visant à améliorer l'évaluation holistique du rendement des résidents dans les unités d'enseignement clinique en médecine interne. Dans cette étude, nous visons à explorer comment ces « vendredis rétroaction ¼ ont contribué à l'évaluation formative des résidents en médecine interne dans le cadre de notre modèle actuel de formation axée sur les compétences. Méthode: Au total, 53 résidents ont participé à des séances d'évaluation de groupe facilitées et bi-hebdomadaires au cours de l'année universitaire 2017-2018. Chaque séance consistait en une discussion d'évaluation facilitée de 30 minutes menée avec une équipe de l'unité de soins, qui comprenait des étudiants en médecine, des résidents et le médecin superviseur. Les commentaires issus de la discussion ont été recueillis, résumés et documentés sous forme narrative dans des formulaires électroniques d'observation directe dans le milieu de travail par le responsable de l'évaluation du programme de résidence. À des fins de recherche, les transcriptions verbatim des séances de rétroaction ont été analysées de façon thématique. Résultats: Les chercheurs ont identifié quatre thèmes principaux pour les commentaires : la communication, la conscience intra- et interpersonnelle, le leadership et le travail d'équipe, et les occasions d'apprentissage. Bien que la rétroaction concerne un large éventail d'activités, elle met fortement l'accent sur les compétences liées aux rôles intrinsèques de CanMEDS. De plus, le fait que la rétroaction avait un rôle clairement formatif est une autre constatation importante. Conclusions: L'introduction de l'évaluation en équipe facilitée dans le programme de médecine interne à Queen's a comblé une lacune importante dans l'apprentissage par observation directe dans le milieu de travail en fournissant aux apprenants une rétroaction détaillée sur tous les rôles CanMEDS et en formulant des recommandations constructives sur les domaines à améliorer.

Integrating Graphene Oxide-Hydrogels and Electrical Stimulation for Controlled Neurotrophic Factor Encapsulation: A Promising Approach for Efficient Nerve Tissue Regeneration.

Nerve growth factor (NGF) plays a crucial role in cellular growth and neurodifferentiation. To achieve significant neuronal regeneration and repair using in vitro NGF delivery, spatiotemporal control that follows the natural neuronal processes must be developed. Notably, a challenge hindering this is the uncontrolled burst release from the growth factor delivery systems. The rapid depletion of NGF reduces treatment efficacy, leading to poor cellular response. To address this, we developed a highly controllable system using graphene oxygen (GO) and GelMA hydrogels modulated by electrical stimulation. Our system showed superior control over the release kinetics, reducing the burst up 30-fold. We demonstrate that the system is also able to sequester and retain NGF up to 10-times more efficiently than GelMA hydrogels alone. Our controlled release system enabled neurodifferentiation, as revealed by gene expression and immunostaining analysis. The increased retention and reduced burst release from our system show a promising pathway for nerve tissue engineering research toward effective regeneration.

All-Soft-Tissue Meniscus Allograft Transplantation With Circumferential Suture Tape Augmentation to Mitigate Hoop Stress and Promote Centralization.

Meniscus allograft transplantation (MAT) is a technically challenging procedure. Bone plugs, slot techniques, and all-soft-tissue fixation techniques have been described in the past. Each technique comes with advantages and disadvantages. Native menisci have circumferential collagen fibers to help resist hoop stress during loading cycles. Although hoop stress resistance is a known function of the menisci, its recreation in MAT has only been targeted indirectly through anatomic root placement. The authors describe the use of a high-tensile suture tape (i.e. InternalBrace) to promote centralization by directly mitigating hoop stresses through recreation of peripheral meniscus tensioning in MAT.

Discrimination in Medical Settings across Populations: Evidence from the All of Us Research Program.

INTRODUCTION: Discrimination in medical settings (DMS) contributes to health care disparities in the United States, but few studies have determined the extent of DMS in a large national sample and across different populations. This study estimated the national prevalence of DMS and described demographic and health-related characteristics associated with experiencing DMS in seven different situations. METHODS: Survey data from 41,875 adults participating in the All of Us Research Program collected in 2021-2022 and logistic regression were used to examine the association between sociodemographic and health-related characteristics and self-reported DMS among adults engaged with a health care provider within the past 12 months. Statistical analysis was performed in 2023-2024. RESULTS: About 36.89% of adults reported having experienced at least one DMS situation. Adults with relative social and medical disadvantages had higher prevalence of experiencing DMS. Compared to their counterparts, respondents with higher odds of experiencing DMS in at least one situation identified as female, non-Hispanic Black, having at least some college, living in the South, renter, having other living arrangement, being publicly insured, not having a usual source of care, having multiple chronic conditions, having any disability, and reporting fair or poor health, p<0.05. CONCLUSIONS: The findings indicate a high prevalence of DMS, particularly among some population groups. Characterizing DMS may be a valuable tool for identifying populations at risk within the health care system and optimizing the overall patient care experience. Implementing relevant policies remains an essential strategy for mitigating the prevalence of DMS and reducing health care disparities.

Survivorship after adolescent and young adult cancer: Models of care, disparities, and opportunities.

Survivors of adolescent and young adult (AYA, age 15-39 years at diagnosis) cancer are a growing population with the potential to live for many decades after treatment completion. Survivors of AYA cancer are at risk for adverse long-term outcomes including chronic conditions, secondary cancers, impaired fertility, poor psychosocial health and health behaviors, and financial toxicity. Further, survivors of AYA cancer from racially minoritized and low socio-economic status populations experience disparities in these outcomes, including lower long-term survival. Despite these known risks, most survivors of AYA cancer do not receive routine survivorship follow-up care, and research on delivering high-quality, evidence-based survivorship care to these patients is lacking. The need for survivorship care was initially advanced in 2006 by the Institute of Medicine. In 2019, the Quality of Cancer Survivorship Care Framework (QCSCF) was developed to provide an evidence-based framework to define key components of optimal survivorship care. In this commentary focused on survivors of AYA cancer, we apply the QCSCF framework to describe models of care that can be adapted for their unique needs, multi-level factors limiting equitable access to care, and opportunities to address these factors to improve short- and long-term outcomes in this vulnerable population.

Impact of Cutaneous Squamous Cell Carcinoma Histologic Features on Percent Interrater Agreement Regarding Tumor Differentiation.

BACKGROUND: Poor differentiation predicts adverse outcomes in cutaneous squamous cell carcinoma (CSCC), but there is no standardized, reliable grading system. OBJECTIVE: To explore which histologic features have the greatest impact on CSCC differentiation interrater agreement. MATERIALS AND METHODS: In a prior study, 40 raters graded differentiation for 45 squamous cell carcinomas, and percent interrater agreements were calculated. Cases graded as well/moderately differentiated with 100% agreement (10), those graded as poorly differentiated with ≥80% agreement (5), and those that received a variety of grades with ≤60% agreement (7) were pulled for the current study. Three raters graded individual histologic features for each case, and percent interrater agreements were calculated using both the well/moderately/poorly differentiated grading system and a dichotomized system. RESULTS: The percent interrater agreements were 34.8% for mitoses, 53% for pleomorphism, 59.1% for keratinization, 66.7% for cellular cohesion/intercellular bridges, and 78.8% for tumor edges. Percent agreements improved with dichotomous grading; the largest improvement was seen within the group of cases that had been graded as well/moderately differentiated with 100% agreement in the prior study. CONCLUSION: Future squamous cell carcinoma differentiation grading systems would benefit from eliminating mitotic rate, clearly defining how to grade other features, and dichotomous grading.

Genomic Landscape of Adenocarcinomas Across the Gastroesophageal Junction: Moving on from the Siewert Classification.

OBJECTIVE: To investigate how the Siewert classification of gastroesophageal junction adenocarcinomas correlates with genomic profiles. SUMMARY/BACKGROUND DATA: Current staging and treatment guidelines recommend that tumors with an epicenter less than 2 cm into the gastric cardia be treated as esophageal cancers, while tumors with epicenter greater than 2 cm into the cardia be staged and treated as gastric cancers. To date, however, few studies have compared the genomic profiles of the 3 Siewert classification groups to validate this distinction. METHODS: Using targeted tumor sequencing data on patients with adenocarcinoma of the gastroesophageal junction previously treated with surgery at our institution, we compared genomic features across Siewert classification groups. RESULTS: A total of 350 patients were included: 121 had Siewert type I, 170 type II, and 59 type III. Comparisons by Siewert location revealed that Siewert type I and II were primarily characterized as the chromosomal instability (CIN) molecular subtype and displayed Barrett's metaplasia and p53 and cell cycle pathway dysregulation. Siewert type III tumors, by contrast, were more heterogeneous, including higher proportions of microsatellite instability (MSI) and genomically stable (GS) tumors and more frequently displayed ARID1A and somatic CDH1 alterations, signet ring cell features, and poor differentiation. Overall, Siewert type I and II tumors demonstrated greater genomic overlap with lower esophageal tumors, while Siewert type III tumors shared genomic features with gastric tumors. CONCLUSIONS: Overall, our results support recent updates in treatment and staging guidelines. Ultimately, however, molecular rather than anatomic classification may prove more valuable in determining staging, treatment, and prognosis.