Biology subjects

Saito, A.

Publications and source records attributed to Saito, A..

At least 19 recordsLinked to original sources

bioRxiv2026

Structure and antigenicity of the 2026 Bundibugyo virus glycoprotein

An outbreak of ebolavirus disease caused by a new zoonotic spillover of Bundibugyo virus (BDBV) is currently spreading at an unprecedented pace in the Democratic Republic of the Congo and Uganda. The outbreak has resulted in 7,733 cases with a case-fatality ratio of 48%, yet no BDBV-specific vaccines or therapeutics are available. The ebolavirus glycoprotein (GP) promotes viral entry and is the target of neutralizing antibodies and vaccine development. Here, we engineered a soluble, prefusion-stabilized GP trimer from a contemporary BDBV isolate and determined its cryo-electron microscopy structure bound to the broadly neutralizing antibody EBOV-515. It reveals the molecular basis for EBOV-515 cross-reactivity and suggests that the antibody inhibits viral entry by interfering with NPC1 engagement in addition to trapping GP in the prefusion conformation and hindering glycan cap cleavage. Mapping lineage-defining substitutions identified changes in GP1 and GP2, including R506S within an antigenic site targeted by multiple broadly neutralizing antibodies recognizing the fusion loop. Nevertheless, we found that several glycan cap-, GP base-, and HR2-directed antibodies cross-reacted and neutralized BDBV DRC/2026 GP pseudovirus with potency comparable or greater to that observed against earlier BDBV isolates and the Zaire ebolavirus Makona/2024 isolate. These findings define the antigenic properties of contemporary BDBV GP and delineate conserved epitopes as ideal targets for antibody therapeutics and for the development of pan-ebolavirus vaccines.

biochemistry↗

bioRxiv2026

Development of a Synthetic Genomics-Based Venezuelan Equine Encephalitis Virus Expressing Secreted Gaussia Luciferase for High-Throughput Antiviral Screening

Venezuelan equine encephalitis virus (VEEV) is a mosquito-borne alphavirus that causes severe neurological disease in humans and animals. Despite its public health importance, no approved antiviral therapy is currently available, and conventional methods for quantifying infectious virus are labor-intensive and poorly suited for high-throughput antiviral screening. Furthermore, research on VEEV is complicated by the restricted availability and international transport of infectious viral materials. Here, we established a full-length infectious cDNA clone of VEEV entirely from chemically synthesized DNA fragments and rescued recombinant reporter viruses expressing mCherry2, ZsGreen, or the secreted Gaussia luciferase mutant 23 (GLucM23). The reporter viruses retained replication kinetics comparable to those of wild-type VEEV, while the fluorescent reporters enabled direct visualization of infection and virus-induced cytopathic effects. GLucM23-expressing VEEV allowed rapid, sensitive, and non-destructive quantification of viral replication directly from culture supernatants, enabling repeated longitudinal measurements without disrupting infected cells. We further demonstrated the utility of this system by screening approximately 3,000 FDA-approved compounds to identify inhibitors of VEEV replication. Together, these findings establish a versatile synthetic genomics-based reporter virus platform for quantitative studies of VEEV replication and scalable antiviral drug discovery.

microbiology↗

bioRxiv2026

The anterior insular cortex mediates higher-order threat learning and memory

Learning about potential threats is indispensable for survival, and its deficits underlie numerous neuropsychiatric disorders. Human brain imaging suggests the anterior insular cortex (AIC) as a key neural correlate of threat learning, yet its mechanistic role remains unclear. Leveraging multimodal systems neuroscience approaches, we demonstrate that AIC excitatory neurons, specifically layer 5 pyramidal neurons projecting to the basolateral amygdala, are essential for higher-order threat learning/memory. They are specifically required when a predictor is temporally separated from an aversive event or when the predictive information is embedded within a diffuse context. In contrast, the AIC is dispensable for elementary, temporally contiguous threat learning. Surprisingly, while the AIC promotes memory formation, it also constrains the level of fear expression during retrieval in a context-dependent manner. This bidirectional control is mediated by the recruitment of distinct AIC neuronal ensembles. Together, we identify a novel circuit mechanism for bidirectional regulation of higher-order threat learning/memory.

neuroscience↗

bioRxiv2026

An Intronic SINE at Pou5f1 Links Hormone Signaling to Blastocyst Hatching

Before implantation, mammalian embryos must escape from the zona pellucida, a protective glycoprotein coat that surrounds the blastocyst. This process, known as hatching, is essential for uterine attachment and has been viewed largely as a mechanical consequence of blastocyst expansion and zona weakening. Whether hatching is actively timed by embryo-intrinsic gene regulation remains unclear. Here we show that timely hatching of mouse embryos requires signal-responsive repression of Pou5f1/OCT4 in the trophectoderm by a single intronic B2 short interspersed nuclear element. Deleting this element preserves blastocyst formation and stem-cell competence, but disrupts trophectodermal OCT4 repression, delays zona escape, causes hatching-uterine receptivity mismatch, perturbs implantation-site organization and reduces peri-implantation fitness. CRISPR activation screening, siRNA and pharmacological perturbation, and defined progesterone/estradiol/EGF culture conditions identify an ESRRA-linked endocrine/growth-factor response that requires the B2 element to consolidate trophectoderm maturation. Comparative analyses further show that young intronic SINEs are enriched in developmental gene programs, whereas human POU5F1 intronic Alu elements exhibit genetic constraint and repressive potential. These findings identify intronic SINEs as molecular entry points that couple extracellular cues to lineage-restricted transcriptional control and morphogenic transition.

developmental biology↗

bioRxiv2026

GALR2 W248L mutation exacerbates neuroinflammation through pro-inflammatory macrophage polarization and microglial activation in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a chronic neuroinflammatory disease characterized by demyelination, neurodegeneration, and progressive neurological disability. Galanin, a neuropeptide with immunomodulatory properties, signals through G protein-coupled receptors, among which galanin receptor 2 (GALR2) has been implicated with neuroprotective and anti-inflammatory functions. A rare homozygous single nucleotide variant in GALR2 (rs61745847; p.W249L) has been identified in a patient diagnosed with relapsing-remitting MS, however, the biological relevance of this variant in neuroinflammation remains unknown. Here, we investigated the impact of the orthologous GALR2 W248L mutation using a knock-in mouse model and experimental autoimmune encephalomyelitis (EAE). GALR2 W248L knock-in (KI) mice exhibited a more severe clinical course of EAE, accompanied by enhanced inflammatory infiltration, exacerbated demyelination, and increased microglial activation in the spinal cord compared with wild-type (WT) mice. Despite comparable lymphoid and myeloid cell frequencies in the central nervous system, alterations in microglial density and morphology suggested an important contribution of the innate immune system to disease exacerbation in the KI mice. Ex vivo analyses revealed that bone marrow-derived macrophages from KI animals exhibited a pronounced shift toward a pro-inflammatory phenotype, characterized by enhanced M1 polarization, impaired M2-associated responses, and increased NLRP3 inflammasome activation. In parallel, live-cell imaging of primary hippocampal neurons demonstrated reduced galanin binding in mutant cells, consistent with impaired GALR2 functional availability at the plasma membrane. Together, these findings identify GALR2 as a modulator of the neuroinflammatory response and indicate that disruption of galanin-GALR2 signaling promotes sustained innate immune activation, highlighting the relevance of this pathway for MS pathogenesis and its potential as a therapeutic target in neuroinflammatory disorders.

molecular biology↗

bioRxiv2026

Comprehensive dissection of GPCR signaling using a NanoBiT-based platform

G-protein-coupled receptors (GPCRs) signal through multiple heterotrimeric G proteins, {beta}-arrestins, GPCR kinases (GRKs), and downstream effectors, whose combinatorial interactions shape cellular responses. These events are typically measured with separate assay formats that each capture only part of the network, making comparison across signaling layers difficult. Here, we consolidate a broad set of previously reported GPCR signaling interactions and assay concepts, together with newly designed sensors, into a single NanoBiT split-luciferase framework, allowing multiple layers of signal transduction to be examined side by side in living cells. We show that rational sensor engineering, in particular the positioning of NanoBiT fragments and targeted modification of the tagged proteins, is essential for detecting transient protein-protein interactions. The framework implements assays for G-protein dissociation, {beta}-arrestin recruitment, conformational activation and trafficking, and GRK recruitment, and extends to G-protein-effector and inter-effector interactions across diverse G, G{beta}, G{gamma}, {beta}-arrestin, GRK, adenylyl cyclase, PLC{beta}, and RhoGEF subtypes. It also enables real-time monitoring of the difficult-to-access G12/13-RhoGEF-RhoA pathway. Together, these assays provide a unified NanoBiT readout for systematic, side-by-side dissection of GPCR signaling.

pharmacology and toxicology↗

bioRxiv2026

Naturally occurring ZCCHC3 variants modulate antiretroviral activity in cynomolgus macaques

Many mammalian cells restrict viral replication by utilizing various host restriction factors. We recently demonstrated that CCHC-type zinc-finger-containing protein 3 (ZCCHC3) suppresses human immunodeficiency virus type 1 (HIV-1) replication through multiple mechanisms. We also revealed that single-nucleotide polymorphisms (SNPs) in human ZCCHC3 affect its antiviral function; however, whether similar genetic and functional diversity is present in other species remains unknown. In this study, we investigated the genetic and functional diversity of ZCCHC3 in cynomolgus macaques, a critical animal model for HIV-1-related research. Sequencing analysis of eight independent ZCCHC3 clones per animal revealed substantial amino acid diversity among cynomolgus macaques. We selected 12 representative variants and examined their antiviral activity against several retroviral vectors derived from HIV-1, simian immunodeficiency virus, feline immunodeficiency virus, and murine leukemia virus. Moreover, using replication-competent HIV-1, we showed that selected cynomolgus macaque ZCCHC3 variants can affect both viral production and viral infectivity. These results suggest that the genetic and functional diversity of ZCCHC3 is not limited to humans and underscore the importance of considering ZCCHC3 variation in cynomolgus macaques when using them as animal models for HIV-1-related research.

microbiology↗

bioRxiv2026

A neural substrate for resistance to change in the ventral hippocampus

Strong prior beliefs can render individuals resistant to change, even when outcomes contradict expectations, yet the neural mechanisms supporting such stability remain poorly understood. Here we show that the ventral hippocampus (vCA1) actively stabilizes inferred contextual state (belief) during aversive memory extinction in a behavior-dependent manner. Using in vivo calcium imaging, we identify a subset of vCA1 neurons that exhibit selective reductions in activity when expected aversive outcomes do not occur during extinction. Axonal calcium imaging further reveals that reduced signals are broadcast to basal amygdala, nucleus accumbens, and medial prefrontal cortex. Optogenetic manipulations demonstrate that these signals actively suppress extinction learning and promote persistence of defensive response. Computational modeling indicates that vCA1 omission-related signals reflect discrepancies between beliefs and observed omission of the expected outcome, thereby maintaining the aversive belief. Crucially, convergent evidence from calcium imaging, modelling, and closed-loop optogenetic manipulations reveals that vCA1 omission-related signals are specific to the period during which animals execute defensive behavior driven by their inferred aversive state. These findings identify a novel mechanism in vCA1 that stabilizes inferred aversive state despite changes in stimulus contingencies and suggest a key role of vCA1 in belief-based control of learning.

neuroscience↗

bioRxiv2026

APOBEC3 antagonism fully explains HIV-1 Vif essentiality under interferon and differentiation conditions

HIV-1 virion infectivity factor (Vif) counteracts APOBEC3 (A3) proteins by targeting them for proteasomal degradation, thereby preventing lethal G-to-A mutations and loss of infectivity. However, Vif also degrades additional cellular proteins, raising the possibility that its essential role in infectious virion production may extend beyond A3 antagonism, particularly under inflammatory or differentiation conditions. Whether such conditions reveal additional essential Vif targets remains unresolved. Here, using interferon (IFN)-stimulated or phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 monocytic cells, we directly addressed this question. Although type I IFN and PMA markedly suppressed viral production through Vif-independent mechanisms, {Delta}Vif viruses produced from stimulated parental cells exhibited severely reduced infectivity. In contrast, disruption of A3A-A3G fully restored {Delta}Vif infectivity to wild-type levels under all conditions tested. G-to-A mutations were attributable exclusively to A3 proteins under both IFN and PMA stimulation, whereas IFN-induced, A3-independent blocks to reverse transcription were not antagonized by Vif. Across diverse HIV-1 strains, the requirement for Vif was strictly dependent on A3 family proteins. These findings demonstrate that the essential role of Vif is fully explained by antagonism of A3-mediated restriction and that evolutionary pressure on Vif is driven predominantly by the need to counteract A3-mediated restriction and mutagenesis. ImportanceA3 proteins are potent intrinsic antiviral factors that restrict HIV-1 by inducing lethal mutations and impairing reverse transcription. The viral protein Vif counteracts A3-mediated restriction, yet it also targets additional host proteins, raising questions about whether its essential role extends beyond A3 antagonism under inflammatory conditions. Myeloid cells mount IFN responses and undergo transcriptional reprogramming upon differentiation, environments in which additional Vif functions could emerge. Using an A3A-A3G-null monocytic cell model, we show that even under IFN stimulation or PMA-induced differentiation, the requirement for Vif in maintaining HIV-1 infectivity is due to A3 proteins. In contrast, Vif does not counteract IFN-induced, A3-independent restriction pathways, highlighting functional specificity. These findings establish the A3-Vif axis as the central determinant of Vif dependency and indicate that evolutionary pressure on Vif is driven predominantly by the need to evade A3-mediated restriction. Targeting Vif may therefore expose HIV-1 to intrinsic inactivation, even in inflammatory environments.

microbiology↗

bioRxiv2026

Dopamine vesicles are specified by mechanisms overriding canonical synaptic vesicle size constraints

Dopaminergic neurons contain distinct synaptic vesicle (SV) populations that segregate dopamine from glutamate, but the molecular basis of this segregation remains unclear. Using an established in vitro SV reconstitution system in fibroblasts, we show that synaptogyrin family proteins--synaptogyrin 1, synaptogyrin 2 and synaptogyrin 3--but not synaptophysin, selectively associate with VMAT2-positive dopamine vesicles in the presence of synapsin. Despite the known role of synaptophysin and synaptogyrin family proteins in generating small SVs (40-50 nm), VMAT2 vesicles retain a larger size (50-80 nm) when co-expressed with synaptogyrins, while remaining segregated from synaptophysin-containing vesicles. SV2 family proteins (SV2A, SV2B, and SV2C) localize to both VMAT2- and synaptophysin-positive vesicle populations, with SV2C preferentially enriched on VMAT2-positive dopamine vesicles. Consistent with the selective dystrophy of SV2C/VMAT2/DAT-positive dopaminergic terminals in parkinsonism-associated SJ1RQKI mice, iPSC-derived dopaminergic neurons carrying the same mutation accumulate small and enlarged SV-like organelles within autophagosomes, indicating defective SV clearance. Together, our findings suggest that dopamine vesicles are regulated by distinct trafficking mechanisms that override canonical SV size control, providing insight into the selective vulnerability of dopaminergic terminals in Parkinsons disease.

neuroscience↗

bioRxiv2026

High-Resolution 3D Histology of the Murine Kidney Using Synchrotron X-Ray Micro-CT

Conventional two-dimensional (2D) histology relies upon destructive sample preparation and stereological estimation, frequently leading to sampling bias and loss of critical spatial context required for understanding renal structure relationships. Here, we detail a novel pipeline for high-resolution 3D histology of ex vivo murine kidneys using X-ray micro-computed tomography (micro-CT) at the high flux of a synchrotron light source, the architecture of the nephron and associated microvasculature necessitates three-dimensional (3D) analysis to accurately characterize its complexity. Soft-tissue contrast was optimized through an established phosphotungstic acid (PTA) staining protocol, enabling robust mapping of macro and microstructures via absorption contrast. Multi-scale imaging was performed, providing whole-organ context at resolutions around 3 m and achieving sub-micron detail (down to 400 nm) in targeted regions of interest (ROI) of the renal cortex. Utilizing machine learning segmentation pipelines optimized for large volumetric datasets, we extracted crucial 3D quantitative morphometric data. The results presented herein demonstrate accuracy and morphological insight achievable through synchrotron-based 3D imaging, establishing a robust method for quantitative preclinical research.

systems biology↗

bioRxiv2026

In vivo xenogenic reconstitution of human alveolar epithelial architecture and function

An urgent need exists for lung models that accurately replicate human physiological profiles. We developed a chimeric mouse model enabling targeted ablation of alveolar type 2 (AT2) cells and lung macrophages, creating niches for endoscopically transplanted human induced pluripotent stem cell (hiPSC)-derived lung progenitors (hLPs). These engrafted cells were retained for 24 weeks, demonstrating self-renewal and differentiation potential, surfactant protein secretion, and maintaining alveolar phosphate homeostasis, suggesting their maturation into AT2 cells. Furthermore, transplantation of hLPs derived from disease-specific hiPSCs recapitulated the phenotype of pulmonary alveolar microlithiasis. The architecture, function, and metabolism of human alveolar epithelium were accurately replicated in vivo. This model has the potential to link experimental models and first-in-human studies, facilitating the development of novel therapies for intractable lung diseases.

developmental biology↗

bioRxiv2025

Development of a non-invasive diagnostic method for pathogenic RNA viruses using sebum wiped from the cat's body surface

The development of non-invasive diagnostic methods for zoonotic viral infections is increasingly important for both animal welfare and public health. Sebum-based diagnostic methods using commercial oil-blotting films have been applied to SARS-CoV-2 detection in humans, yet equivalent strategies for veterinary use remain largely unexplored. Severe fever with thrombocytopenia syndrome (SFTS), caused by the SFTS virus (SFTSV), presents a major health threat in Asia--especially in Japan, where multiple cases of cat-to-veterinarian transmission have been reported. To address the need for safer diagnostics, we sought to establish a sebum-based RNA virus detection method for cats. We designed primers that efficiently detected RNA from feline sebum while distinguishing it from human and feline DNA/RNA. Using this platform, we determined the ear to be the optimal sebum collection site and confirmed that feline immunodeficiency virus (FIV) RNA can be reliably identified from ear sebum with sensitivity comparable to conventional blood-based testing. In addition, we detected SFTSV RNA from sebum samples of infected cat. Our findings introduce a minimally invasive, safe diagnostic platform for feline viral infections, reducing animal distress while safeguarding veterinarians and pet owners from zoonotic risks. This strategy marks an important step toward realizing the One Health framework by advancing the well-being of both animals and humans.

microbiology↗

bioRxiv2025

Development of a Porcine Cell Line Stably Expressing Ephrin-B2 for Nipah Virus Research and Diagnostic Testing

Nipah virus (NiV) is a highly pathogenic zoonotic virus transmitted from bats to humans through pigs as a crucial intermediate host. NiV outbreaks pose significant public health and economic threats, especially for pig farmers. Although the World Organization for Animal Health (WOAH) recommends African green monkey-derived Vero cells for NiV isolation, pig-derived cell lines could represent an optimal platform for propagating pig-origin NiV, as signs and symptoms of NiV infection differ among different hosts. In this study, we generated and evaluated pig-derived PK-15 cells stably expressing pig-derived ephrin-B2 (PK-15/Ephrin-B2 cells), the primary receptor for NiV. NiV pseudovirus infectivity was increased by >1000-fold in PK-15/Ephrin-B2 cells compared with that in wild-type PK-15 cells, whereas virus susceptibility was higher in PK-15/Ephrin-B2 cells than in Vero cells (>30-fold). Furthermore, Stat2-knockout PK-15/Ephrin-B2 cells exhibited stable viral infectivity in the presence of type I interferon, making it particularly suitable for clinical sample testing. Moreover, PK-15/Ephrin-B2 cells proved useful for neutralization tests using anti-NiV hyperimmune ascitic fluid. Therefore, PK-15 cells expressing pig ephrin-B2 could represent an efficient tool for virus isolation, vaccine development, and virological studies of NiV and related henipaviruses.

microbiology↗

bioRxiv2025

DISC1-PML protein interaction for congenital CMV infection-induced cortical neural progenitor deficit: perturbance of host signaling via viral IE1

Congenital CMV infection is the most common perinatal infection, affecting up to 0.5% of infants. This elicits long-term disabilities that include neuropsychiatric manifestations, such as intellectual disability, microcephaly. Despite its high prevalence, the underlying mechanism of how congenitally acquired CMV infection causes brain pathology remains unknown. Here we discovered the molecular interplay of key host (DISC1 and PML) and viral (IE1) proteins within the neural progenitor cells, which underlay an attenuated neural progenitor proliferation. Abolishing the viral IE1 protein by delivering IE1-targeting CRISPR/Cas9 to fetal brain rescued this progenitor cell deficit, a key pathology in congenital CMV infection. A selective targeting to a viral-specific protein by the CRISPR/Cas9 system is minimal in off-target effects. Therefore, we believe that a pivotal role of IE1 in an attenuated neural progenitor proliferation in the developing cortex through its interfering with interaction between host DISC1 and PML proteins.

developmental biology↗

bioRxiv2025

Lenacapavir binding to immature Gag triggers the emergence of giant HIV-1 virions

Lenacapavir (LEN), a potent capsid inhibitor, suppresses reverse transcription and nuclear import by disrupting capsid core formation in human immunodeficiency virus type 1 (HIV-1). However, its effect on the late-stage viral assembly remains unclear. Although p24 ELISA suggested that LEN inhibited HIV-1, both RT-dPCR and Vpr-HiBiT assays indicated no reduction in the viral output. This discrepancy was attributed to LEN-induced epitope masking of p24, which was reversed by altered sample processing. Furthermore, LEN induced numerous abnormal, discrete clusters of Gag at the plasma membrane. Mass photometry and transmission electron microscopy revealed heterogeneous viral-like particles (LENiVLPs; diameter >200 nm), containing both Gag and Env proteins. Although LENiVLPs retained membrane fusion capability, they were non-infectious owing to post-entry defects. Thus, LEN binds to the precursor Gag and promotes aberrant particle formation, offering novel insights that could guide the development of next-generation LEN-based therapeutics targeting the late stages of the viral life cycle.

microbiology↗

bioRxiv2025

Genital herpes shedding episodes associate with alterations in the spatial organization and activation of mucosal immune cells

Herpes Simplex Virus 2 (HSV-2) infection results in variable rates of local viral shedding in anogenital skin. The impact of episodic viral exposures on immune cells in adjacent mucosal tissues, including the genital tract, is unknown. However, any immune responses at this site could impact protective mucosal immunity, tissue homeostasis, and adverse health outcomes. To investigate the impact of HSV-2 on cervicovaginal tract immunity, we applied flow cytometry, immunofluorescent imaging, analysis of soluble immune factors, and spatial transcriptomics to cervicovaginal tissue and blood samples provided by a total of 232 HSV-2 seropositive and seronegative participants, with genital HSV-2 shedding evaluated at the time of biopsy. This unique dataset was used to define and spatially map immune cell subsets and localized gene expression via spatial transcriptomics. HSV-2 seropositivity alone was associated with minimal differences in cervicovaginal and circulating T cell phenotypes. However, the vaginal mucosa during active HSV-2 shedding was associated with alterations in T cell, macrophage, and dendritic cell localization and gene expression consistent with increased immune surveillance, with immune activating and suppressing signals potentially reinforcing mucosal tissue homeostasis. SummaryIn context of episodic HSV-2 shedding, immune cells mobilize and co-localize in the vaginal epithelium, expressing cytotoxic and inflammatory genes and immunoregulatory genes that collectively may promote tissue homeostasis in settings of episodic viral shedding to limit damage.

immunology↗

bioRxiv2025

Concordance of claudin-18.2 expression in biopsy, resection, and recurrent specimens: implications for zolbetuximab therapy in pancreatic ductal adenocarcinoma

Claudin-18.2 is a promising therapeutic target for gastrointestinal cancer. However, its expression pattern in pancreatic ductal adenocarcinoma, especially the concordance between biopsy and resection specimens, is unknown. This study aimed to evaluate the consistency of claudin-18.2 positivity across different specimen types using the clinically validated antibody clone 43-14A employed in ongoing zolbetuximab trials. Immunohistochemical analysis for claudin-18 was conducted on 211 resected pancreatic cancer tissues, 133 matched preoperative biopsy samples, and 60 samples from recurrent lesions. Concordance rates were calculated based on a clinically relevant cutoff ([≥]75% of tumor cells with moderate-to-strong membranous staining). Receiver operating characteristic analysis was used to optimize the biopsy thresholds. Claudin-18.2 positivity was observed in 9.5% of the resection specimens. The concordance rates were 92.5% between biopsy and resection specimens and 83.3% between primary and recurrent lesions. Receiver operating characteristic analysis suggested that a lower cutoff (20%) in biopsy samples achieved 100% sensitivity for detecting positive cases. While overall claudin-18 expression levels were maintained in most recurrent lesions, decreased expression was frequently observed in cases of local recurrence and liver metastasis. Despite intrinsic heterogeneity and limited biopsy yield in pancreatic cancer, claudin-18 expression in small biopsy samples, assessed using the clinical trial-validated clone 43-14A, strongly correlated with that in resection specimens. These results suggest that claudin-18.2 is a clinically stable biomarker for zolbetuximab therapy in patients with pancreatic ductal adenocarcinoma. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/648482v2_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@1b822e5org.highwire.dtl.DTLVardef@1fb03f0org.highwire.dtl.DTLVardef@bfa888org.highwire.dtl.DTLVardef@d1a015_HPS_FORMAT_FIGEXP M_FIG C_FIG Core TipsO_LIThis study demonstrated a high concordance (92.5%) of CLDN18.2 positivity between preoperative biopsy and resected pancreatic ductal adenocarcinoma specimens, using the clinical trial-validated antibody clone 43-14A. C_LIO_LICLDN18.2 expression in recurrent lesions generally remained consistent with that in the corresponding primary tumor, although a reduction in expression levels was observed in local recurrence and liver metastases. C_LIO_LIThese findings support the clinical utility of biopsy-based CLDN18.2 evaluation for selecting patients with pancreatic ductal adenocarcinoma who may benefit from zolbetuximab. C_LI

pathology↗