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Early mortality in children with homozygous familial hypercholesterolemia: Case reports of deaths at ages 5 and 7 and a systematic review of global evidence.

BACKGROUND: Homozygous familial hypercholesterolemia (HoFH) is a leading cause of premature atherosclerotic cardiovascular disease (ASCVD) and early mortality if left untreated or inadequately treated. OBJECTIVE: This study presents 2 pediatric cases of early death from Pakistan due to familial hypercholesterolemia (FH) and provides a systematic review of similar cases reported globally. METHODS: Genetic analysis was conducted using next-generation sequencing to confirm pathogenic variants. For the systematic review, published reports of individuals with FH who died before the age of 18 years were identified. Data were extracted on demographic features, personal and family history, genetic variants, treatment given, and cause of death. RESULTS: Both patients, born to consanguineous families, presented with markedly elevated low-density lipoprotein cholesterol (LDL-C) levels (792 mg/dL [20.48 mmol/L] and 896 mg/dL [23 mmol/L], respectively), multiple xanthomas, and early-onset myocardial infarction, and died at the ages of 5 and 7 years, respectively. Their genetic analysis revealed a pathogenic frameshift variant in the LDLR gene: NM_000527.5: c.2416dupG (p.Val806GlyfsTer11). The systematic review included 12 studies reporting pediatric FH-related mortality. Common clinical features included tendon xanthomas, elevated LDL-C levels, family history, and early-onset ASCVD. Genetic testing was performed in a few cases, which revealed pathogenic variations in the LDLR gene. Most of the patients received inadequate lipid-lowering therapy. The most common causes of death were severe coronary artery disease, myocardial infarction, and sudden cardiac arrest. CONCLUSION: Our 2 cases and the accompanying systematic review identified additional cases of premature mortality. Collectively, these findings highlight diagnostic delays and inadequate treatment as common factors among patients who died prematurely.

Child↗

Cross-kingdom dynamics of the subgingival bacteriome and mycobiome: A pilot study on the effects of a novel HA-H₂O₂-Glycine formulation to treat periodontitis.

OBJECTIVES: Traditional periodontal therapy primarily focuses on bacterial biofilm control; however, recent evidence also suggests a critical role for the oral mycobiome. This study evaluated the clinical and ecological impact of a novel mouthwash formulation containing hyaluronic acid (HA), hydrogen peroxide (H2O2), and glycine on periodontal patients METHODS: This prospective, randomized split-mouth trial included 13 adult participants with periodontitis treated with HA-H2O2-glycine formula (BMG0703A) used twice a day for seven days. Subgingival plaque samples were collected from periodontal pocket and healthy control sites at baseline (T0) and one-week post-treatment (T1). Microbial and fungal communities were characterized using Next-Generation Sequencing (NGS) of the 16S rRNA and ITS2 regions. Linear Mixed Models (LMM) and Spearman correlation were used to assess taxonomic shifts and cross-kingdom relationships. RESULTS: Sequencing revealed a promising ecological shift: the bacteriome shifted from anaerobic dominance (Olsenella, Peptostreptococcus) toward a health-associated aerobic profile, with Rothia near-doubling (11.91% to 22.68%). The mycobiome underwent a "normalization" effect: Candida abundance decreased significantly (22.8% to 9.1%), while fungal Shannon diversity in pockets returned to healthy-site levels. Inter-kingdom analysis identified antagonistic relationships between expanding commensal bacteria and opportunistic fungi, suggesting that the intervention may help re-establish a protective bacterial niche. CONCLUSIONS: The HA-H2O2-glycine formulation seems to facilitate a rapid, cross-kingdom modulation of the subgingival niche. By reducing anaerobic pathogens and normalizing the mycobiome it appear to induce short-term changes, suggesting potential as adjunctive strategy in periodontal management. CLINICAL SIGNIFICANCE: The present work underlines the possible cross-Kingdom effects of a novel compound.

Humans↗

Whole mitogenome profile of Pelung and Sentul chickens to reveal potency of Indonesian livestock genetic resources.

Native chickens are essential genetic resources in Indonesia, providing economic, cultural, and nutritional value with strong adaptability to local environments. Among these native chickens, Sentul and Pelung are recognized as national genetic resources due to dual-purpose and ornamental traits, respectively, but their whole mitogenome characterization remains limited. Therefore, this study aimed to assemble and analyze the whole mitogenome of Sentul and Pelung chickens as well as perform a comparison with 35 additional genomes from domestic chickens and jungle fowls across Asia. The experiment was carried out using next-generation sequencing and bioinformatics-based genome assembly and analysis. The results showed that both Sentul and Pelung genomes were 16,784 bp in length and contained the typical mitochondrial gene composition, including 13 protein-coding genes (PCGs), 22 transfer ribonucleic acids (tRNAs), two ribosomal ribonucleic acids (rRNAs), and a control region (D-loop). Furthermore, comparative analysis identified five single-nucleotide polymorphisms (SNPs) distinguishing the two breeds, located in ND1, COX1, COX2, ND4, and the D-loop region. Phylogenetic reconstruction based on whole mitochondrial sequences showed that Sentul and Pelung chickens belong to haplogroup D, alongside other native breeds and red jungle fowls from Indonesia and the Philippines.

Genetic diversity↗

A novel missense mutation in tropomyosin 1 gene associated with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a common genetic heart disorder that can lead to heart failure or sudden death. Family-based identification of rare sarcomeric variants can support molecular diagnosis and cascade screening in inherited HCM. This study aimed to identify and evaluate a novel TPM1 variant found in a Vietnamese family with HCM. The proband, a 3-year-old boy diagnosed with HCM, and eight relatives from three generations underwent clinical and genetic evaluation. A candidate variant initially identified by targeted next-generation sequencing was validated by PCR and Sanger sequencing. Familial segregation analysis was performed, and variant pathogenicity was assessed according to ACMG guidelines with support from in silico prediction and structural modeling. Sanger sequencing confirmed a heterozygous missense variant in exon 6 of TPM1 NM_001018005.2:c.576G > C, p.(Glu192Asp), in the proband, his father, and paternal grandfather, all of whom exhibited clinical signs of HCM. The variant was absent in unaffected relatives and in public population databases. Based on ACMG criteria (PM1, PM2, PM5, and PP3), the variant was classified as likely pathogenic. This novel TPM1 variant segregated with HCM in a Vietnamese family, expands the known mutational spectrum of TPM1 in hypertrophic cardiomyopathy, and warrants further functional investigation and familial genetic evaluation.

American College of Medical Genetics and Genomics ↗

Genome-wide variation analysis of two Salvia hispanica L. genotypes and implication for associations with metabolic and adaptive traits.

BACKGROUND: Advances in next-generation sequencing have accelerated genome-wide exploration of genetic diversity in underutilized oilseed crops. Salvia hispanica L. (chia), a high-nutrient pseudocereal rich in omega-3 fatty acids, is increasingly valued for its health benefits and commercial potential, yet it remains poorly characterized at the genomic level. Understanding the scale and nature of genomic variation is essential for improving complex traits such as oil yield, stress tolerance, and seed quality. METHODS: Two contrasting chia genotypes, Black-chia (CACH-B) and White- chia (CACH-W), were resequenced using the Bio-Resequencing Toolkit (BRT) pipeline. High-coverage sequencing, with a mapping rate exceeding 99% and an average depth of approximately 28×, facilitated the detection and annotation of single-nucleotide polymorphisms (SNPs), insertions and deletions (InDels), copy-number variations (CNVs), and structural variants (SVs). The functional classification of variant impacts enabled the identification of genes potentially linked to metabolic and adaptive traits. RESULTS: A total of 1.97 million SNPs, 401,493 InDels, 836 CNVs, and 15,288 SVs were identified across the chia genome. Notably, approximately 53% of exonic SNPs were non-synonymous (dN/dS ≈ 1.28), predominantly affecting lipid metabolism, transcriptional regulation, and stress response pathways, potentially altering key agronomic traits. In addition, CNV hotspots were concentrated in chromosomes 3 and 6, overlapping MYB, WRKY, and bZIP transcription factor loci, may potentially be involved in stress tolerance and yield. Furthermore, structural rearrangements, including inversions and duplications within the FAD2, FAD3, and CYP450 gene clusters, were potentially associated with seed pigmentation and omega-3 biosynthesis, pointing to their potential breeding relevance. Observed heterozygosity (Hₒ ≈ 0.71) and nucleotide diversity (π ≈ 7 × 10-3) indicated moderate to high allelic richness. In addition, the low FST value (0.038) indicates substantial genomic similarity between the two genotypes. CONCLUSION: This study presents the first comprehensive map integrating SNPs, CNVs, and SVs in S. hispanica L. The results reveal a structurally dynamic genome characterized by substantial sequence and structural variation, providing valuable insights into genomic diversity and potential adaptive mechanisms in chia. The coexistence of high SNP diversity and abundant structural variation underpins chia's nutritional specialization and environmental resilience. These results deliver a foundational genomic resource for marker-assisted breeding, genome-wide association studies, and the development of climate-resilient chia cultivars.

Copy-number variation, structural variation↗

Comprehensive Microbiome Analyses for Regenerative Endodontic Therapy.

INTRODUCTION: Comprehensive microbiome analyses include the study of all microbial taxa, including bacteria, archaea, viruses, and fungi, as well as their functional activities and antibiotic resistance gene expression. Regenerative endodontic therapy presents a clinical situation where the most effective antimicrobial approaches are needed in order to ensure clinical success. METHODS AND RESULTS: In this paper, different contemporary technologies for the identification of endodontic microorganisms, such as with next generation sequencing, and their functional characterization, such as with whole genome sequencing, are described. The role of transcriptomics, as well as resistome analysis, are also discussed. Furthermore, the manner in which all this work and knowledge could be incorporated into clinical endodontics in general, and regenerative endodontic therapy as a special treatment, is outlined. CONCLUSIONS: Comprehensive microbiome analysis can lead to the development of more effective and personalized antimicrobial treatment.

Endodontics↗

A Single-Arm Phase 2 Study of Sotorasib Plus Carboplatin and Pemetrexed in Patients With Advanced Nonsquamous NSCLC With KRAS G12C Mutation (WJOG14821L, SCARLET).

INTRODUCTION: The efficacy and safety of sotorasib plus platinum doublet chemotherapy in KRAS G12C-mutated nonsquamous NSCLC (nonsq NSCLC) have been previously reported with a limited follow-up period. METHODS: SCARLET is a single-arm phase 2 study involving chemotherapy-naive patients with KRAS G12C-mutated nonsq NSCLC. The participants received 960 mg daily plus four cycles of carboplatin (area under the curve = 5)/pemetrexed 500 mg/m2, followed by sotorasib/pemetrexed until disease progression. The primary end point was the overall response rate (ORR) and the secondary end points were progression-free survival (PFS), overall survival, and safety. Using plasma samples, next-generation sequencing was performed at baseline, 3 weeks, and during disease progression (the Japan Registry of Clinical Trials number 2051210086). RESULTS: Thirty patients were enrolled between October 2021 and July 2022 with a median follow-up of 14.8 months. ORR was 88.9% (80% confidence interval [CI]: 78.5%-94.8%, 95% CI: 70.8%-97.6%), median PFS was 6.6 months (95% CI: 5.3-16.7 mo), and median overall survival was 20.6 months (95% CI: 8.1 mo-not estimated). Among patients with programmed death-ligand 1 expression levels of 1% or higher and less than 1%, the ORRs were 82.3 and 100%, respectively, and the median PFS was 7.6 and 9.7 months, respectively. Using plasma samples, patients without KRAS G12C at baseline, without KRAS-related pathway co-alterations, or who cleared KRAS G12C at 3 weeks had better median PFS (16.7, 13.9, 8.7 mo, respectively). Tumor protein 53 mutations and EGFR and MET amplification were detected as acquired resistance. CONCLUSIONS: In patients with KRAS G12C-mutated nonsq NSCLC, sotorasib plus carboplatin/pemetrexed reported favorable efficacy, particularly for patients with less than 1% programmed death-ligand 1, with manageable toxicity.

Humans↗

Molecular Profiling Across 80,000 Patients With Lung Cancer.

INTRODUCTION: Biomarker testing is an essential component of optimal therapeutic management in NSCLC, enabling the use of both Food and Drug Administration-approved and emerging targeted therapies. Despite well-established biomarker testing guidelines and the availability of many approved targeted therapies, a substantial proportion of patients with advanced NSCLC are not benefiting from precision oncology. In this study, we analyze the distribution of actionable genomic alterations across histologic subtypes and clinicodemographic subgroups of NSCLC using data in 82,328 samples profiled with a single comprehensive genomic profiling assay, aiming to support universal molecular testing across all NSCLC subtypes to ensure equitable access to available therapeutics. METHODS: This is an observational retrospective analysis on histologically confirmed NSCLC cases tested with comprehensive genomic profiling by next-generation sequencing between 2014 and 2022 using Foundation One/Foundation CDx. All cases were centrally reviewed by board-certified anatomic pathologist to determine histologic type and subtype. RESULTS: A total of 82,328 patients with NSCLC were included. An actionable genomic alteration (GA) was found in 35.1% of the cases. Lung adenocarcinoma (LUAD) and adenosquamous carcinoma were more frequently associated with actionable GA (45.8% and 40.9%, respectively) as compared with sarcomatoid (29.1%), not otherwise specified (27.6%), large cell (21.1%), and squamous cell (6.5%) histologies. Sarcomatoid histology had the highest METex14 skipping mutation (mut) frequency (9.95% versus 2.43% in LUAD). Tumor mutation burden more than or equal to 10 mut/Mb was associated with histology (50.91% in large cell, 40.79% in not otherwise specified, 39.08% in squamous cell, and 36.30% in sarcomatoid versus 31.22% in LUAD and 29.22% in adenosquamous carcinoma). Patients with actionable GA had usually a low tumor mutation burden (80.88%). A significant correlation (p < 0.005) between age and actionable GA was reported for BRAF/ERBB2 muts, ALK/RET/ROS1 rearrangements, and MET amplification. EGFR actionable muts and KRAS G12C were more frequently observed in females, whereas no significant correlation between sex and other GA was observed. Finally, genetic ancestry analyses revealed a strong correlation for EGFR actionable muts and South/East Asia and America, but not for other GA. CONCLUSIONS: This is the largest NSCLC data set analyzed for biomarker distribution across histologies, age, sex, and genetic ancestry. This data set confirms sufficient enough biomarker prevalence across many histologic subtypes of NSCLC, providing reassurance that all NSCLC cases should be considered for biomarker workup.

Humans↗

Molecular diagnostic tests for isoniazid-resistant tuberculosis: a scoping review.

The paucity of diagnostic tests for isoniazid-resistant tuberculosis is concerning, given its status as the most common form of drug-resistant tuberculosis and a gateway to multidrug-resistant diseases. Molecular drug-susceptibility testing has improved access to timely diagnosis of rifampicin-resistant tuberculosis, but testing for isoniazid-resistant tuberculosis still remains rare. In this Review, we assessed the characteristics of molecular drug-susceptibility testing for detection of isoniazid-resistant tuberculosis, referencing the WHO target product profiles. 9243 citations were screened to select 238 studies published between 2000 and 2024. The diagnostics options have expanded rapidly since 2020, with 27 nucleic acid amplification tests, eight line probe assays, five DNA microarrays, two targeted next-generation sequencing platforms, and two whole-genome sequencing platforms. Most of the evaluated molecular drug-susceptibility tests met diagnostic performance targets but were often complex and costly. Although a few low-complexity nucleic acid amplification tests met key target product profile criteria, additional field validation and greater efforts are needed to ensure optimal feasibility and affordability for low-resource settings.

Isoniazid↗

Genomic Profiling, Risk Stratification, and Post-Transformation Treatment Outcomes in Patients with Transformed Small-Cell Lung Cancer: A Multicenter Analysis.

BACKGROUND: Transformed small-cell lung cancer (T-SCLC) is an increasingly recognized resistance mechanism in EGFR-mutant lung adenocarcinoma. This study aimed to identify early predictors of histologic transformation and evaluate post-transformation treatment outcomes. METHODS: We retrospectively collected 163 T-SCLC patients from five Chinese centers. Next-generation sequencing was performed on 60 EGFR-mutant patients, including 47 paired primary-transformed samples. Integrated genomic and clinical analyses were conducted to delineate molecular features and survival outcomes. RESULTS: Among 150 EGFR-mutant patients, the median time to SCLC transformation was 25.8 months and median post-transformation overall survival (OS) was 14.2 months. Clinical and survival data for the 13 EGFR wild-type patients are reported descriptively given the limited sample size. Among 108 treatment-evaluable patients, first-line EGFR-TKI plus chemotherapy, chemotherapy alone, and immune checkpoint inhibitors (ICIs) plus chemotherapy yielded median progression-free survival (PFS) of 6.2, 5.30, and 4.07 months (P = 0.041) and median OS of 21.2, 27.6, and 13.6 months (P = 0.193). In later-line therapy, taxane-based regimens achieved a median PFS of 6.93 months, outperforming camptothecin-based (1.13 months) and other regimens (1.90 months; P = 0.049). High evolutionary diversity was associated with shorter post-transformation OS (6.77 vs. 11.10 months), with restricted cubic spline analysis showing a nonsignificant trend toward a nonlinear association (P = 0.055).Age, RB1/NTRK1 mutation, and secondary T790M mutation were identified as independent risk factors and integrated into a predictive model with high accuracy. CONCLUSIONS: This study establishes a clinically applicable model for early prediction and risk stratification of SCLC transformation. Taxane-based regimens emerge as a promising later-line therapeutic option for T-SCLC.

Humans↗

Large cell neuroendocrine carcinoma of the lung: Current standards, emerging targets, and translational foundations.

Pulmonary large cell neuroendocrine carcinoma (LCNEC) is one of the most complex and heterogenous clinical entities in thoracic oncology, sharing features with both non-small cell lung cancer (NSLC) and neuroendocrine lung cancers. LCNEC diagnosis and classification relies on evolving histopathological and molecular criteria that define its diagnostic boundaries. Recent advances have confirmed the dual nature of LCNEC, with distinct small cell-like and non-small cell-like molecular characteristics, which guide treatment decisions. In this review, we synthesize current evidence on the diagnosis, molecular characterization, and multimodality management of LCNEC to provide a comprehensive framework for clinical and translational decision-making. A comprehensive literature search was conducted using the PubMed database with no date restrictions, last updated on 12th of April 2026. Articles were selected based on relevance to the diagnosis, molecular characterization, and management of pulmonary LCNEC. Emphasis was placed on studies providing clinical, pathological, and molecular insights into the field. In this review, we summarize contemporary diagnostic approaches, including the expanding role of immunohistochemistry, next&#x2011;generation sequencing, and integrated morpho&#x2011;molecular assessment. This review represents a consolidated update on LCNEC genomic and transcriptional landscapes, and actionable molecular alterations that are anticipated to impact treatment decisions. Additionally, it provides a state-of-the-art overview of multimodality management, covering surgical approaches, radiotherapy, perioperative therapy, systemic treatment, and the emerging role of immunotherapy. Despite incremental progress, LCNEC remains constrained by limited prospective data and lack of consensus on optimal treatment pathways. By conducting literature review, we identified persistent gaps in LCNEC published data and hereby highlight key priorities for future research.

Humans↗

Complex IV deficiency due to COX4I1 deep intronic and de novo variants results in progressive motor impairment and Leigh syndrome.

COX4I1 gene encodes cytochrome c oxidase subunit 4 isoform 1, involved in the early assembly stages of mitochondrial respiratory chain complex IV. To date, COX4I1 pathogenic variants have been reported in only a few cases, each exhibiting heterogeneous clinical phenotypes and limited functional data. Here, we describe the fourth reported case of COX4I1 deficiency associated with human disease, expanding the phenotypic and genetic spectrum of this rare mitochondrial disorder and providing novel clinical, molecular, and functional data. The herein reported individual presented with progressive deterioration of motor skills, intellectual disability and brain imaging abnormalities compatible with Leigh syndrome. Genetic studies combining short and long read next generation sequencing uncovered a peculiar genetic combination in this patient, harboring a de novo COX4I1 nonsense substitution in trans with an inherited deep intronic variant (c.[64C>T];[73+1511A>G]; p.[Arg22Ter];[Glu25ValfsTer9]). Functional studies performed in patient's tissues and transiently transfected cell lines demonstrated that the identified variants mainly exert their pathogenic effect by targeting COX4I1 protein levels, thereby impairing the proper assembly and activity of complex IV.Additionally, proteomic data in patient's fibroblasts suggested an underlying pathomechanism that involves not only the regulation of complex IV function but also the levels of mitoribosomal proteins. In summary, our findings shed light to clarify some of the main clinical features associated with COX4I1 deficiency and the molecular mechanisms involved in the pathogenesis of this disorder.

Humans↗

Molecular Landscape, Genomic Shift, and Prediction in the Neoadjuvant Setting of Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer.

The amplification or overexpression of human epidermal growth factor receptor 2 (HER2) defines a breast cancer subtype, which benefits from neoadjuvant HER2-targeted therapy. However, at least 40% of patients respond poorly or do not respond to treatment. We analyzed the main genomic alterations of 64 HER2+ patients by next-generation sequencing to identify new predictors of response and correlate them with clinicopathological parameters. We also compared the genomic alterations between primary and residual tumors after neoadjuvant treatment. The TP53 gene was the most frequently mutated gene, and in combination with ERBB2 overexpression, the 2 were predictive of residual cancer burden (P = .001). Furthermore, the combination of their immunohistochemical counterpart (p53 mutant and score 3+ for HER2) can predict complete pathological response and the grade of response (P = .038 and P = .031, respectively). Therefore, p53 could be included in the initial panel of breast cancer biomarkers to help therapeutic decision-making in HER2+ cases.

Humans↗

Population-Specific Immunogenomic Alterations in Gallbladder Cancer and Prognostic Significance.

Gallbladder carcinoma is a deadly disease with a poor prognosis, and recent clinical data suggest only a modest benefit of PD1/PDL1 inhibitors in this disease. Optimizing immunotherapeutic approaches will require a detailed understanding of the immunogenomic landscape of this disease worldwide. We combined targeted next-generation sequencing and immunohistochemistry to create detailed immunogenomic landscapes from 2 cohorts of gallbladder cancer cases from the United States (n = 60) and Chile (n = 62). Mutations in TP53, SMAD4, KRAS, PIK3CA, ARID2, ARID1A, ATM, FBXW7, ERBB2, and NF1 were found in both the US and Chilean primary cohorts, as well as amplifications in ERBB2, CCNE1, MDM2/CDK4, and CCND1. Despite similar mutation profiles, the immune profiles were distinct, with the Latin American cohort having higher densities of biomarkers associated with CD4+ T cells and PD-1 but lower densities of CD68+ macrophages compared with the North American cohort. Clustering and correlation analyses suggest novel immune subgroups and clinical associations independently of any specific mutations. Additionally, supported by multiplexed single-cell imaging technology, we identified low CD4 and high V-domain Ig suppressor of T cell activation as a candidate biomarker pair of poor outcomes. In summary, our findings highlight the importance of sensitivity to geographic location when considering therapeutic developments and pave a path for further immune investigations of this understudied disease.

Humans↗

Optical Genome Mapping in Myelodysplastic Syndromes: Clinical Value and Limitations Derived From a Cohort of 236 Patients.

Identification of cytogenetic abnormalities is critical for the classification and risk stratification of myelodysplastic syndromes (MDS). Optical genome mapping (OGM) is an emerging cytogenomic platform that enables high-resolution genome-wide cytogenetic analysis. We analyzed bone marrow specimens of 236 MDS patients, 149 newly diagnosed and 87 with relapsed/refractory disease, using OGM, conventional karyotyping, and next-generation sequencing analysis. OGM and karyotyping showed concordant results in 68% of cases, including 34% with normal findings by both assays. OGM provided additional information in 27% of patients. Common abnormalities detected exclusively by OGM included chromoanagenesis (n = 33), KMT2A partial tandem duplication (n = 7), and MECOM rearrangement (n = 4). These OGM findings led to disease reclassification and/or changes in risk stratification in 14 patients (9.4%) with newly diagnosed MDS. In contrast, OGM failed to detect small clones or subclones in 5% of patients, resulting in risk group changes in 2% of newly diagnosed MDS patients. We conclude that OGM enhances the cytogenetic assessment of MDS in approximately 25% of patients and leads to a change in disease classification and/or risk stratification in approximately 10% of patients. However, low sensitivity for detecting small clones or subclones remains a limitation of OGM.

Humans↗

Loss of Methylthioadenosine Phosphorylase (MTAP) Expression: A Potentially Useful Tool for Distinguishing Sarcomatoid Urothelial Carcinoma From Inflammatory Myofibroblastic Tumor.

Inflammatory myofibroblastic tumor (IMT) and sarcomatoid urothelial carcinoma (SarUC) can have striking histologic overlap but have significantly different prognoses and clinical management paradigms. Loss of methylthioadenosine phosphorylase (MTAP) protein expression by immunohistochemistry (IHC) serves as a useful surrogate for homozygous 9p21 deletion, a recurrent genomic alteration in urothelial carcinoma (UC). We analyzed MTAP expression by IHC in 65 SarUCs and 27 urinary tract IMTs to evaluate its utility in navigating this challenging differential diagnosis. Overall, MTAP loss was significantly more frequent in SarUC (55%) compared with IMT (4%) (P < .0001). Among 46 biphasic SarUCs with independently evaluable epithelial and mesenchymal components, divergent expression patterns were frequent. The most common pattern was retention of MTAP staining in both epithelial and mesenchymal components (19/46; 41% of cases), followed by selective retention of MTAP in the epithelial component and loss in the mesenchymal component (16/46; 35% of cases). MTAP loss was observed in both the epithelial and mesenchymal components in 11 out of 46 (24%) SarUC cases. None of the 46 biphasic SarUC cases showed selective MTAP loss in the epithelial component but retention in the mesenchymal component. MTAP IHC was also particularly valuable in assessing clonal relationships in 2 challenging biphasic cases in which the differential diagnosis included a collision between a noninvasive low-grade papillary UC and an IMT versus a subtle IMT-like SarUC arising in association with an overlying noninvasive low-grade papillary UC. Next-generation sequencing on a subset of cases (n = 11) was useful for confirming 9p deletion in cases with MTAP loss by IHC, and for demonstrating molecular hallmarks of urothelial neoplasia thereby providing additional diagnostic support for morphologically challenging SarUC cases with IMT-like morphology. Therefore, MTAP IHC can be useful in evaluating spindle cell lesions of the urinary tract, as loss is significantly more common in SarUC than in IMT, and enriched in the mesenchymal component of biphasic SarUC. However, MTAP loss can be seen in both entities, and the diagnosis of IMT-like spindle cell tumors in the urinary tract requires careful integration of morphologic, immunohistochemical, and molecular data.

Humans↗

RNF43 Mutations Are Associated With the Classical Molecular Subtype, Vigorous Antitumor Immune Responses, and Prolonged Survival in Pancreatic Adenocarcinoma.

RNF43 mutations were correlated with microsatellite status in colorectal cancer and with fewer and later recurrences in pancreatic ductal adenocarcinoma (PDAC). Here, we undertake a detailed assessment of RNF43 mutations in PDAC. A total of 313 PDACs (308 microsatellite stable [MSS] and 5 microsatellite-instable [MSI] cases) underwent next-generation sequencing (Oncomine Tumor Mutation Load assay; Thermo Fisher). Spatial analyses (NanoString) classified PDACs according to their transcriptomic and proteomic immune signaling. Fluorescent imaging was used to define spatial compartments (tumor: pancytokeratin+/CD45- and leukocytes: pancytokeratin-/CD45+). Each of 20 PDACs with RNF43 mutations (RNF43mut) and without RNF43 mutations (RNF43wt) underwent multiplex immunofluorescence analysis to determine immune status. A total of 153 PDACs (22 RNF43mut and 131 RNF43wt cases) underwent bulk RNA sequencing to assign into molecular subtypes. Overall, 24 RNF43 mutations were identified (22 MSS PDACs and 2 MSI PDACs). The incidence of RNF43 mutations in MSS PDACs (7.1%) was consistent with The Cancer Genome Atlas (6.7%). However, RNF43 mutations were more frequent among MSI PDACs (40%). Additionally, RNF43mut had differential frequencies of other mutations (including Wnt pathway genes), higher tumor mutational burden values (5.5 mut/mb vs 1.67 mut/mb; P < .01), and significantly longer overall survival (47 vs 18 months; P < .0001) than RNF43wt. Moreover, RNF43mut exhibited significantly higher densities of CD8+ T lymphocytes, dendritic cells, and B lymphocytes (P < .001) and an upregulation of ITGAX, CD11c, CD8, and HLA-DR compared with RNF43wt. Patients with RNF43mut PDACs were more often of the classical molecular subtype (20/22, 90.9%). RNF43mut PDACs showed high tumor mutational burden values, suggesting increased neoantigen load coupled with an abundance of antigen-presenting immune cells and an upregulation of immune determinants promoting antigen presentation. All this contributes to stronger antitumor immune responses and improved clinical outcomes.

Humans↗

Genomic Characterization of Classic Adamantinoma, Osteofibrous Dysplasia, and Osteofibrous Dysplasia-like Adamantinoma.

Classic adamantinoma, osteofibrous dysplasia (OFD), and OFD-like adamantinoma are rare bone tumors arising primarily in the tibiae. Their distinction can be challenging; data on their molecular pathogenesis remain limited. We searched our pathology files in 2004-2024 for available cases and performed targeted next-generation sequencing along with whole-genome single-nucleotide polymorphism arrays and 3-dimensional genomics/Hi-C sequencing in selected cases. Our cohort included 3 classic adamantinomas (2 females and 1 male; age, 14-56 years), 5 OFDs (3 females and 2 males; age, 9-25 years), and 2 OFD-like adamantinomas (1 female and 1 male; age, 30-41 years). Of the 10 tumors, 9 arose from the tibiae; 1 classic adamantinoma originated from the radius. The 3 classic adamantinomas harbored multiple copy number gains involving chromosome 7, 8, 10, 12, and/or 19. Focal deletion of chromosome 17, intergenic rearrangement involving FGFR1, and NRAS p.G12D were each present in 1 classic adamantinoma. Of the 5 OFDs, KMT2A p.C2441F, KMT2D p.S1040P, PHOX2B p.G213D, and RIF1 deletion were each present in 1 case; no additional copy number/single-nucleotide variants were identified. Of the 2 OFD-like adamantinomas, one case with tumor clusters visible only on cytokeratin immunostain harbored no variants, whereas another case with tumor clusters visible on light microscopy and cytokeratin/p40 immunostains showed gains of chromosome 7, 8, 19, and 20. By Hi-C, 1 classic adamantinoma harbored an approximately 9 Mb tandem duplication on chromosome 12q, 1 OFD harbored a rearrangement with breakpoints near MECOM and HOOK3, and the OFD-like adamantinoma with tumor clusters visible only on cytokeratin immunostain harbored no structural variant. In conclusion, classic adamantinomas and OFD might be genetically distinct. Classic adamantinomas harbored multiple alterations, including chromosome/arm-level copy number gains, the detection of which could aid their distinction from OFDs. Using genomics as the benchmark, OFD-like adamantinomas might be better delineated by light microscopy or p40 than by cytokeratin immunohistochemistry. These data expanded our molecular understanding of these rare bone tumors.

Humans↗