Transplantation

Background: Each year around 4,500 people in the UK receive an organ transplant. These surgeries can be life changing and life extending for patients but are also associated with significant costs for the health service. However, by reducing the need for other expensive interventions involved in non-transplant care for organ failure, such as dialysis, some of these costs may be recovered. Methods: We assessed the lifetime costs and benefits associated with transplantation focussing on deceased donor adult transplants for kidneys, livers, hearts, and lungs. We incorporated costs of organ retrieval, surgery, post-transplant secondary care, and medications, as well as impacts on quality and duration of life. These were compared to the cost of managing patients with end-stage organ failure for whom no transplant occurs. Results: Kidney transplants were found to be cost saving with lifetime costs approximately 220,000 GBP lower than alternative treatment. Heart transplants and liver transplants were found to be more cost-effective than thresholds used by NICE for new medicines at approximately 17,000 GBP to 18,000 GBP per quality adjusted life year gained. Lung transplants were the least cost-effective organ transplant with a cost per quality adjusted life year gained of over 50,000 GBP. Conclusions: Although transplants can be costly, not providing a transplant to a patient who needs one also brings significant costs. Kidney transplants can save the health system money by reducing the need for dialysis. Increasing the number of kidney's available for transplant could save the NHS money whilst saving and improving lives.

Key PointsO_ST_ABSQuestionC_ST_ABSDoes the circadian timing of stem cell infusion influence the risk of aGVHD after allo-PBSCT? FindingsIn this randomized prospective clinical trial that included 198 patients, infusion stem cell at 12:00 pm at noon was associated with a significantly lower incidence and less severity of aGVHD compared with infusion at 6:00 pm, without influencing engraftment or relapse. MeaningScheduling stem cell infusion at an earlier time-of-day may reduce aGVHD risk after allo-PBSCT. IMPORTANCEAcute graft-versus-host disease (aGVHD) remains a major complication following allogeneic peripheral blood stem cell transplantation (allo-PBSCT), compromising patient survival and quality of life. OBJECTIVETo evaluate the effect of stem cell infusion time-of-day on aGVHD after allo-PBSCT. DESIGNA multicenter, randomized, open-label, phase 3 clinical trial was conducted from March 18, 2024, through June 11, 2025, with follow-up through December 31, 2025 (median, 462 days among survivors). SETTINGSix transplantation centers in China. PARTICIPANTSPatients aged 12 to 60 years with malignant hematologic diseases undergoing first allo-PBSCT were screened; 198 eligible patients were randomized. INTERVENTIONSPatients were randomly assigned in a 1:1 ratio to receive stem cell infusion at either 12:00 pm at noon ({+/-} 0.5 hour) or 6:00 pm ({+/-} 0.5 hour). MAIN OUTCOMES AND MEASURESThe primary end point was the cumulative incidence of grade II-IV aGVHD within 100 days after transplantation. Secondary end points included grade III-IV aGVHD, hematopoietic recovery, transplant-related mortality (TRM), relapse, and survival outcomes. RESULTSAmong 198 randomized patients (median age, 38 years; 119 [60.1%] male), grade II-IV aGVHD within 100 days occurred in 11 of 99 patients (11.1%) in the 12:00 pm group and 22 of 99 patients (23.2%) in the 6:00 pm group. The cumulative incidences of grade II-IV and III-IV aGVHD were significantly lower in the 12:00 pm group (II-IV: 11.1% [95% CI, 5.9%-18.2%] vs 23.2% [95% CI, 15.4%-32.0%], P = 0.029, hazard ratio, 2.18 [95% CI, 1.06-4.48]; III-IV: 2.0% [95% CI, 0.4%-6.5%] vs 12.2% [95% CI, 6.7%-19.5%], P = 0.006, hazard ratio, 6.25 [95% CI, 1.39-28.15]). There were no significant differences in hematopoietic recovery, TRM, or relapse between groups. The estimated probability of GVHD-free, relapse-free survival (GRFS) at 360 days favored the 12:00 pm group (66.7% [95% CI, 56.2%-75.2%] vs 56.5% [95% CI, 46.1%-65.5%]). CONCLUSIONS AND RELEVANCEStem cell infusion at 12:00 pm was associated with a lower incidence and severity of aGVHD compared with infusion at 6:00 pm, without influencing engraftment or relapse. Optimization of infusion timing may represent a simple strategy to reduce aGVHD risk. TRIAL REGISTRATIONClinicalTrials.gov Identifier: NCT06294678.

Background: Antibody-mediated rejection (AMR) after heart transplant (HT) is associated with increased risk of mortality and graft loss. Contemporary studies delineating AMR presentation, management, and response to treatment are lacking, especially for patients who do not have typical immunohistological evidence of rejection (biopsy-negative, BN-AMR). In this study, we sought to describe the prevalence and clinical course of BN-AMR compared to biopsy-positive (BP-AMR) patients in a multicenter HT population. Methods: We conducted a retrospective analysis of all adult HT recipients at 2 academic medical centers. AMR was further divided into BP-AMR and BN-AMR, depending on their endomyocardial biopsy findings. The primary outcome was death and secondary outcome was a composite of death, retransplant, and new International Society of Heart and Lung Transplant grade 2 or 3 coronary artery vasculopathy. Results: A total of 742 patients were included in this study. We found that AMR occurred in 10% of HT recipients and was associated with worse overall survival compared to those with only cellular rejection or no rejection. BN-AMR accounted for 33% of AMR cases. Compared to BP-AMR, BN-AMR was diagnosed later, less aggressively treated, and associated with high morbidity and mortality. The long-term outcomes between BP-AMR and BN-AMR were similarly poor, with 5-year mortality approaching 50% after diagnosis. Conclusions: AMR after HT is associated with poor clinical outcomes and BN-AMR is common. Future studies should focus on incorporating novel tools for earlier detection of AMR and investigating AMR sub-phenotypes and optimal modes of treatment.

Early complications following allogeneic hematopoietic stem cell transplantation (allo-HSCT), including graft-versus-host disease (GVHD) and viral reactivation, remain major causes of post-transplant morbidity, but whether immune perturbations precede these events remains unclear. We performed longitudinal TCR{beta} repertoire profiling in 108 allo-HSCT recipients and their corresponding donors at baseline and three early post-transplant time points to characterize immune reconstitution dynamics. Reduced baseline TCR diversity was most strongly associated with subsequent Epstein-Barr virus (EBV) reactivation, whereas cytomegalovirus (CMV) reactivation was more closely linked to post-transplant repertoire remodeling characterized by clonal expansion and reduced donor-recipient repertoire similarity. Sequence-based predictive modeling demonstrated meaningful discrimination, with fusion models achieving area under the curve (AUC) values of 0.745 for CMV, 0.819 for EBV, and 0.834 for GVHD. Temporal analyses further revealed complication-specific predictive windows. These findings indicate that major post-transplant complications are preceded by detectable immune perturbations and support the potential utility of TCR repertoire monitoring for early risk stratification after transplantation.

Heart transplantation (HT) is the durable therapy for end-stage heart failure (HF). Despite advances in immunosuppression, cardiac allograft vasculopathy (CAV) remains a leading cause of late graft failure and mortality in the modern era. Prior studies have established donor age and immunological phenomena, such as acute cellular rejection (ACR), antibody-mediated rejection (AMR), and development of donor-specific antibodies (DSAs) as risk factors for CAV. However, it remains unclear whether acute rejection (AR) that occurs early post-HT, when individuals experience the highest degree of immunosuppression, reflects higher baseline immune activity and confers a higher risk of future CAV compared to later AR, when immunosuppression is minimized. We therefore examined whether AR occurring during pre-specified early and intermediate intervals compared to those who did not experience AR in the first post-HT year was associated with future CAV among recipients without CAV at 1 year.

Despite extensive pretransplant serological screening and HLA matching, 10-15% of kidney allografts experience acute rejection within the first year. Currently, risk stratification for transplantation relies primarily on antibody reactivity to HLA molecules, with no assessment of the T cell compartment before or after transplantation. In our previously established longitudinal cohort of 54 patients, T cell receptor {beta} (TCR{beta}) sequencing was performed on paired kidney biopsy and peripheral blood samples. Here, we further analyzed the data to construct a comprehensive set of sequence-similarity networks and quantify over 30 network metrics. After adjusting for repertoire size, graft status was the strongest signal for the underlying differences in network metrics. Individuals who rejected the kidney graft generally exhibited more fragmented and less connected networks at baseline, with fewer interconnect T cell clones and more isolated sequences. Notably, pre-transplant peripheral blood mononuclear cell (PBMC) network topology alone predicted non-stable outcomes with an area under the curve (AUC) of 0.81, sensitivity of 76%, and specificity of 76%. The performance of this prediction model was independent of HLA mismatch, while changes in network topology at three months post-transplantation further improved prediction to an AUC of 0.88 (permutation p = 0.009). Collectively, TCR sequencing and network analysis represent a potential novel, non-invasive approach for pre-transplant risk stratification and immune monitoring, capturing functional immunological risk that may not be accessible through HLA genotyping or serology.

BackgroundKidney transplantation is the preferred treatment strategy for end-stage kidney disease. Deceased donor kidneys usually undergo cold storage until kidney transplantation, leading to cold ischemia injury that may contribute to poor graft outcomes. However, the molecular characterization of potential mechanisms of cold ischemia injury remains incomplete. ResultsTo bridge this knowledge gap, we leveraged the 10x Visium spatial transcriptomic technology to perform full transcriptome profiling of murine kidneys subject to varying durations of cold ischemia typical in a deceased donor kidney transplant setting. We developed a computational workflow to identify and compare spatiotemporal transcriptomic changes that accompany the injury pathophysiology in a tissue compartment-specific manner. We identified proportional enrichment of oxidative phosphorylation (OXPHOS) genes with increasing duration of cold ischemia injury within the oxygen-lean inner medulla region, suggestive of atypical metabolic presentation. This was distinct in cold ischemia injury tissue compared to warm ischemia-reperfusion kidney injury tissue. Spatiotemporal trends were validated by qPCR and immunofluorescence in a larger cohort of mice. We provide an interactive online browser at https://jef.works/CellCarto-ColdIschemia/ to facilitate exploration of our results by the broader scientific and clinical community. ConclusionsAltogether, our spatiotemporal transcriptomic analysis identified coordinated molecular changes within metabolic pathways such as OXPHOS deep within the cold ischemic kidney, highlighting the need for increased attention to the inner medulla and potential opportunities for new insights beyond those available from superficial biopsy-focused tissue examinations.

Background: Primary graft dysfunction (PGD) remains one of the leading causes of early mortality after pediatric heart transplant (HT). While neurodevelopmental impacts of congenital heart disease (CHD) are well-characterized, the effect of PGD on long-term neurodevelopmental outcomes in pediatric HT recipients remains unknown. We sought to determine the association between PGD and neurodevelopmental outcomes in this population. Methods: We performed a retrospective cohort study using the United Network for Organ Sharing (UNOS) database. All pediatric (age <18 years) isolated heart transplant recipients from 2010-2025 were included. The most recent pre- and post-transplant neurodevelopmental outcomes including cognitive delay, motor development, academic progress, and function status (stratified by age) were compared between PGD (n=434) and non- PGD groups (n=6956). Results: PGD patients had significantly worse pre-transplant functional status and motor development. Post-transplant, PGD was associated with worse motor development (18.8% vs. 13.0% definite motor delay; p=0.01) and functional status in younger children (39.5% vs. 57.8% able to keep up with peers; p<0.001). Post-transplant stroke occurred 3.5 times more frequently in PGD patients (11.5% vs. 3.3%; p<0.001). Cognitive development (p=0.94) and academic progress (p=0.096) did not differ significantly. Thirty-day (7.8% vs. 1.9%) and 1-year mortality (20.3% vs. 6.4%) were significantly higher in PGD patients (both p<0.001). Conclusions: This is the first study to characterize neurodevelopmental outcomes in pediatric patients undergoing HT with PGD. PGD is associated with significantly worse motor development and functional status independent of pre-transplant baseline. There is a 3.5-fold higher stroke rate providing a plausible neurological mechanism. The findings support targeted developmental surveillance recommendations and early intervention for this high-risk population.

Background: Modern therapy for childhood and adolescent leukemia requires accurate risk classification of genomic subtype. Although short-read next-generation sequencing (NGS)- based approaches provide comprehensive clinical diagnostics in limited, highly resourced settings, they remain expensive, slow, and inaccessible to most children worldwide. Transformative approaches are needed to improve diagnostic classification for leukemia globally. Methods: We simultaneously continued to develop an analytical pipeline NASVar (Nanopore variant calling for adaptive sampling), and conducted a multicenter, type-two hybrid clinical validation study of an Oxford Nanopore Technologies (ONT) adaptive-sampling whole-genome sequencing (asWGS) assay across hospitals with varying diagnostic resources. In preparation for implementation, a global panel developed a leukemia-based standardized gene set and consensus laboratory-developed test (LDT) validation guidelines. Measures of assay effectiveness compared to both conventional and orthogonal NGS methods, where available, were simultaneously collected with data to measure the implementation outcomes of feasibility, fidelity, appropriateness, and cost. Results: All four centers successfully completed the LDT validation, with minimal adaptations required for regulatory compliance. A total of 457 specimens were sequenced (331 B-ALL, 83 AML, 43 T-ALL). For the 210 B-ALL cases with locally resolved genomic subtypes defined by DNA alterations, asWGS was 100% concordant (210/210). Cases locally defined as B-other were resolved via asWGS with disease-defining DNA alterations in 47% (49/105) of cases. An additional 41% (43/105) of locally defined B-other cases were classified by incorporation of DNA methylation, and all 16 B-ALL patient-derived xenograft controls were correct, for a total of 96% (318/331) of all B-ALL cases in the cohort resolved with single assay asWGS. For AML, 97% (56/58) of cases with locally resolved genomic subtypes were identified by automated asWGS analysis, while an additional two cases were identified after targeted manual review. At Indus Hospital in Pakistan, the B-ALL and AML diagnostic genomic subtype yield increased from 28% with local standard of care diagnostic testing, to 84% with asWGS. The cost of reagents and consumables in the United States, assuming pooled three-plexing, was $343/sample. Based on the combined hybrid validation results, all centers are independently preparing for clinical return of results. Conclusions: ONT asWGS was successfully validated as a clinical assay in four diverse hospital settings. As a single, multi-omic platform that delivers value across the continuum of high-resource to resource-limited contexts, the approach offers a disruptive solution to address the global equity gap in cancer diagnostics.

BackgroundWe aimed to identify data-driven FEV1 trajectory phenotypes post-chronic lung allograft dysfunction (CLAD), relate these phenotypes to patient factors and future graft loss, and develop a classification approach for prospective patients. MethodsWe studied adult first lung recipients with probable CLAD from two prospective multicenter cohorts: CTOT-20 (n=206) and LTOG (n=1418). FEV1 trajectories over the first nine months post-CLAD were characterized using joint latent class mixed models, jointly modelling time-to-graft loss to account for informative censoring. Models were fit independently in both cohorts and also only among LTOG bilateral recipients. A classification and regression tree (CART) model was derived in LTOG bilateral recipients and applied to CTOT-20 bilateral recipients. FindingsFour distinct early FEV1 trajectory classes were identified in CTOT-20, with large differences in nine-month graft loss (72{middle dot}3%, 31{middle dot}1%, 2{middle dot}2%, 0%). In LTOG, similar trajectory patterns were reproduced, with an additional class demonstrating early post-CLAD FEV1 improvement. Among bilateral recipients, trajectory classes showed a clear risk gradient, including a high-risk class with 100% graft loss and a low-risk class with no early graft loss. A CART model incorporating clinical and spirometric variables demonstrated good discrimination in LTOG bilateral recipients (multiclass AUC 0{middle dot}85) and consistent class assignment and trajectory patterns when applied to CTOT-20. InterpretationWe identified reproducible, clinically meaningful early post-CLAD FEV1 trajectory phenotypes with differential graft loss risk. These phenotypes and a pragmatic classification tool may support risk stratification, trial enrichment, and improved prognostication for patients and clinicians. FundingNational Institutes of Health, Cystic Fibrosis Foundation

Tacrolimus is an immunosuppressant drug commonly used in transplantation. Although multiple studies have demonstrated that polymorphisms in the CYP3A5 gene impact the metabolism of tacrolimus, routine pre-transplant testing for these markers is still not broadly implemented. TacroType - a new laboratory developed test implemented by One Lambda Laboratories - utilizes a qPCR-based six-plex assay for CYP3A5 genotyping and detects the three most common genetic variants (*3, *6 and *7) associated with loss of CYP3A5 protein function and reduced tacrolimus metabolism. TacroType was optimized to address known sources of protocol, technical or sample variability to achieve accurate and reproduceable genotyping results. An analytical performance study was completed following CLSI guidelines. Accuracy was confirmed for each possible CYP3A5 genotype involving 6 target alleles using 32 well-characterized reference samples. TacroType exhibited accurate performance within a broad range of DNA concentrations and quality. Precision studies indicated consistent genotyping results across 4 operators, 2 instrument types and 5 lots of reagents. Accurate and reproducible assay performance was demonstrated using whole blood from 100 and buccal swabs from 70 donors. The analytical performance of TacroType was evaluated in 4014 total qPCR reactions, with a report rate of 99.8% and genotyping accuracy of 100% (95% confidence interval of 99.9%).

The intestinal microbiome influences immune recovery and long-term outcomes after allogeneic hematopoietic stem cell transplantation (allo-SCT). While reduced bacterial diversity and depletion of immunomodulatory microbial metabolites during peri-engraftment have been linked to acute graft-versus-host disease (aGvHD) and mortality, it remains unclear whether microbiome recovery after engraftment and immune reconstitution is better reflected by bacterial diversity or by microbial metabolic output. We aimed to define microbiome recovery in the late post-transplant period and test whether a metabolite-based biomarker improves the prediction of clinical outcomes, including overall survival (OS) and chronic (c) GvHD. In this two-center longitudinal observational study, serial stool samples were collected from pre-transplant baseline to day +100 after allo-SCT in a discovery cohort (n = 20, Technical University Munich University Hospital (TUM)) and an independent validation cohort (n = 100, University Hospital Regensburg (UKR)). Gut microbiome composition was assessed by 16S rRNA gene amplicon sequencing, with metagenomic profiling in selected patients, and stool metabolites were quantified using targeted mass spectrometry. Patients were classified as RECOVERY or NO RECOVERY based on changes in bacterial richness between baseline and the post-transplant period. To capture microbial metabolic output, the previously established Immune-Modulatory Metabolite Risk Index (IMM-RI), comprising butyric, propionic, and isovaleric acids, desaminotyrosine and indole-3-carboxaldehyde, was adapted to the late post-transplant period (IMM-RI post-TX). Bacterial alpha diversity frequently improved by day +100; however, this did not consistently indicate restoration of baseline community structure and was not paralleled by recovery of stool metabolite profiles. Accordingly, RECOVERY status showed a limited association with survival or transplant-related mortality (TRM). In contrast, IMM-RI post-TX low-risk identified patients with preserved butyrate-associated biosynthetic capacity and was significantly associated with improved OS in both cohorts (UKR: HR 0.2052, 95% CI 0.07703 - 0.5466, p < 0.0001). In the validation cohort, IMM-RI post-TX low-risk was significantly associated with reduced relapse-related mortality. Interestingly, stool butyric-, propionic and valeric acid concentrations were increased in cGvHD of the skin, indicating context-dependent metabolite effects. These findings suggest that metabolite profiling outperforms bacterial diversity for predicting outcomes after allo-SCT and support microbial metabolites as promising biomarkers for risk stratification and actionable candidates for precision microbiome interventions after allo-SCT.

Tuberculosis screening is not mandatory for prospective tissue donors. In 2021 and 2023, two different bone allograft products caused nationwide tuberculosis outbreaks. We assessed the morbidity and mortality of the second outbreak and reviewed donor and tissue screening to identify deficiencies. Thirty-six people residing in nine states received the product during spinal and dental procedures. Twenty-seven recipients had tuberculosis infection, 11 had microbiologic or imaging evidence of tuberculosis disease, and two died from tuberculosis within 12 months of outbreak detection. Another recipient died from tuberculosis nearly 3 years after product implantation. The bone donor died of pneumonia and septic shock. Polymerase chain reaction testing of the product before and after distribution did not detect Mycobacterium tuberculosis. Mycobacterial culture was not performed until after outbreak detection, when M. tuberculosis was isolated from 2 of 6 unused product units. This outbreak demonstrates persistent gaps in tissue transplant safety. Appropriate selection of donors and mycobacterial culture of donated tissues could reduce but not eliminate the risk of M. tuberculosis transmission. Therefore, it is important that clinicians monitor tissue recipients and promptly report adverse events to tissue establishments and health authorities.

iii.Background and ObjectivesThe "Pan-European Transfusion Research InfrAstructure" (PETRA) project was established to advance the use of donor, blood product, and patient datasets in Europe, aiming to benefit both patient and donor health. Here, the initial PETRA objective was to describe the landscape of existing donor and blood establishment (BE) databases. Materials and MethodsAn online survey was circulated to the European Blood Alliances BE members. The survey collected information on the feasibility of accessing donor data, and challenges and possibilities for linking these datasets with information on the associated blood products and transfusion recipients, and donors own health records. ResultsSeventeen BEs across 16 countries completed the survey. The majority could, in principle, link their donor data to product data (13 BEs (76%)) and recipient data (10 BEs (59%)), for research purposes. However, capabilities were limited and in only 29% of the BEs was the donor to recipients linkage an automated process. BEs reported significant challenges to achieve full vein-to-vein linkage, including legal constraints and lack of consent (11 BEs) and resources (10-14 BEs). IT and data issues as well as lack of knowledge and training were cited as obstacles by a minority of BEs. ConclusionWhilst the survey results suggest considerable interest in developing linkages between blood donors, their products, and recipients, many challenges remain due to a variety of obstacles. First steps in working towards a PETRA may be assistance to navigate legal frameworks as well as investing in resources and quality and harmonisation of data collections. iv. HighlightsO_LI17 blood establishments (BEs) in 16 countries responded to a survey on obstacles and opportunities for achieving vein-to-vein datasets. C_LIO_LIIn 59% of the BEs donor-to-recipient links can be established for research improving transfusion outcomes, but only in 29% this is an automated process. C_LIO_LIIn order to work towards a "Pan-European Transfusion Research InfrAstructure" (PETRA), legal frameworks, adequate donor consent and (financial and human) resources are the most common obstacles that require addressing. C_LI

Background: Multiple myeloma (MM) remains incurable despite therapeutic advances, reflecting limited understanding of the molecular mechanisms underlying disease initiation and progression. MM develops through asymptomatic precursor stages, monoclonal gammopathy of undetermined significance (MGUS) and smouldering multiple myeloma (SMM). This study aimed to investigate protein changes associated with disease progression and, through a further integrative approach, to highlight molecular changes of potential predictive and/or therapeutic value. Methods: We performed a comparative proteomic analysis of 94 bone marrow-derived CD138+-selected plasma cell samples (29 MGUS, 20 SMM, and 45 MM) using LC-MS/MS. Differential protein abundance was assessed using pairwise Mann-Whitney U tests between groups, with Benjamini-Hochberg correction. Pathway enrichment, protein-protein interaction, and co-expression network analyses were also conducted. Selected proteins were further evaluated using public transcriptomic datasets and experimentally validated in independent samples by flow cytometry and enzyme-linked immunosorbent assay (ELISA). Results: Following data processing, proteomic analysis identified 6,203 proteins. Pairwise comparisons revealed significant proteomic differences across disease stages, with 370 differentially abundant proteins exhibiting monotonic changes during disease progression. Pathway analysis showed that monotonically upregulated proteins were mainly associated with gene expression and cell proliferation, whereas downregulated proteins were linked to immune-related processes. Further co-expression network analysis, combined with criteria including detection frequency, biological relevance, and translational potential, highlighted a group of prioritised proteins. Representative examples include nucleolin (NCL) and U3 small nucleolar ribonucleoprotein IMP3 (IMP3), involved in nucleolar organisation, ribosome biogenesis and rRNA processing, as well as the immune-associated lactotransferrin (LTF) and serine protease cathepsin G (CTSG). Transcriptomic support and independent experimental validation by flow cytometry and ELISA confirmed the relevance of selected candidates. Conclusions: Taken together, our findings highlight coordinated changes in immune regulation, RNA processing and ribosome biogenesis during MM progression and identify candidate proteins and their networks, including the emerging pharmacologically tractable target NCL and the underexplored IMP3 of potential therapeutic relevance, opening new avenues for further investigation.

BackgroundTubulitis is a defining histologic feature of T cell-mediated rejection (TCMR), while glomerulitis is often characteristic of antibody mediated rejection (AMR). Histologic quantification of tubulitis and glomerulitis using Banff criteria is subject to interobserver variability. Bulk transcriptomic assays (e.g., MMDx) have introduced molecular correlations of tubulitis with TCMR and glomerulitis with AMR, but lack spatial resolution. MethodsWe applied a web-based platform, FUSION (Functional Unit State Identification in Whole Slide Images), to a cohort of 8 cases (n=2 per condition) with kidney allograft biopsy samples acute TCMR, active AMR, chronic active AMR, and no rejection (control). The machine-learning (ML) platform enabled integrated visualization and analysis of spatial transcriptomics (10x Genomics Visium v2) together with high-resolution whole-slide histology. ResultsTranscriptomics-derived immune cell proportions within AI-segmented tubular and glomerular regions were used to generate spatial Banff t- and g-scores. Derived t-scores showed full concordance with pathologist scores in both acute TCMR cases; g-scores showed concordance in 2 of 4 AMR cases, with discordant cases characterized by low absolute immune signal near the classification boundary. ConclusionsWe demonstrate the feasibility of using AI-based FTU segmentation integrated with spatial transcriptomics-derived immune cell proportions to generate spatially informed t- and g-scores aligned with Banff criteria, with full concordance in severe rejection and partial concordance in mild rejection. This approach lays the foundation for validated, spatial transcriptomics-augmented t-scores and g-scores that enhance diagnostic precision, reduces inter-observer variability among renal pathologists, and support potential clinical adoption.

Background and hypothesis: Sodium-glucose cotransporter-2 inhibitors (SGLT2-inhibitors) slow chronic kidney disease progression, but evidence in non-diabetic kidney transplant recipients is limited. We evaluated associations between SGLT2-inhibitor use and major adverse kidney events (MAKE), major adverse cardiovascular events (MACE), and all-cause mortality. Methods: In this retrospective cohort study using the TriNetX federated research network, adult non-diabetic kidney transplant recipients transplanted between January 2015 and January 2022 were identified. SGLT2-inhibitor users initiating therapy [&ge;]1000 days post-transplant were compared with non-users after 1:1 propensity score matching. The primary outcome was MAKE, defined as dialysis initiation or death. Secondary outcomes included all-cause mortality and MACE. Results: Propensity score matching yielded 867 pairs of SGLT2-inhibitor users and non-users. SGLT2-inhibitor use was associated with lower risks of MAKE (adjusted hazard ratio [aHR] 0.64, 95% CI 0.45-0.91) and all-cause mortality (aHR 0.55, 95% CI 0.36-0.85). No significant association was observed for MACE (aHR 0.86, 95% CI 0.64-1.17). No increased risk of urinary tract infections was observed among SGLT2-inhibitor users. Conclusion: SGLT2-inhibitor use was associated with lower risks of MAKE and all-cause mortality in non-diabetic kidney transplant recipients.

Current clinical management of multiple myeloma (MM) relies on bone marrow (BM) biopsies for minimal residual disease (MRD) assessment. While BM biopsies are the gold standard, their invasive nature and potential to miss extramedullary or patchy disease necessitate sensitive, non-invasive liquid biopsy platforms. In this study, we evaluated the analytical performance of the CellSearch CMMC assay to determine its utility for deep-MRD monitoring. Using a standard 4 mL whole blood input, the assay achieves a WBC-normalized sensitivity of 2.45 x 10-7, supported by a limit of quantitation of 5 cells per run. Given this high analytical sensitivity, the assay provides a robust negative predictive value, rendering false-negative findings highly unlikely in populations with detectable peripheral disease. These findings characterize the CellSearch CMMC assay as a highly sensitive, analytically validated platform for non-invasive deep-MRD level longitudinal surveillance monitoring. When integrated into a clinical workflow that accounts for its specificity profile, the platform offers a patient-friendly complement to serial BM biopsies, with the potential to reduce their frequency in appropriate clinical contexts.

BackgroundChimeric antigen receptor (CAR)-T cell therapies efficacy in solid tumors remains limited, largely due to the profoundly immunosuppressive tumor microenvironment (TME) which drives CAR-T cells to dysfunction and poor persistence. A comprehensive understanding of the dynamic interplay between CAR-T cells and the TME is therefore critical for the rational design of more effective CAR-T strategies for solid cancers. MethodsHere, we performed single-cell RNA sequencing of tumor samples from immunocompetent mice treated with stroma-targeting EDA-CAR-T cells, profiling CAR-T cell states and TME programs at the peak of antitumor response and during subsequent tumor progression. ResultsOur analysis revealed a marked temporal remodeling of EDA-CAR-T cells within the TME, where early antitumor efficacy is associated with concurrent expansion of cytotoxic effector CD8 CAR-T cells and activation of memory CD4 CAR-T subsets. Moreover, EDA-CAR-T cells effectively engaged the myeloid compartment, resulting in strengthened communication networks involving T cell activation. However, by tumor progression, EDA-CAR-T cells suffered a widespread transcriptional reprogramming towards dysfunction, characterized by loss of effector programs alongside induction of exhaustion and immunoregulatory pathways within the TME, including PD-L1/PD-L2 and TGF{beta} signaling, which impairs sustained immune responses. Notably, early CAR-T cell activation led to increased susceptibility to TME-mediated immunosuppression, revealing EDA-CAR-T-specific soluble galectin-mediated cell-to-cell interaction networks. ConclusionsTogether, this works offers a high-resolution view of CAR-T cell dynamics within the solid TME, uncovering cellular and molecular mechanisms of rapid functional decline and identifying regulatory pathways within the TME that can be exploited to improve CAR-T cell therapy efficacy in solid tumors. KEY MESSAGES OF THE ARTICLEO_ST_ABSWhat is already known on this topicC_ST_ABSThe determinants of CAR-T cell therapeutic efficacy in solid tumors remain poorly defined, largely due to the complexity of the immunosuppressive tumor microenvironment. In this effort, it is necessary to perform comprehensive and detailed mechanistic studies that capture CAR-T cell dynamics within the solid tumor microenvironment to understand treatment failure. What this study addsWe performed single-cell profiling of stroma-targeting EDA-CAR-T cells, revealing their dynamic reprogramming toward dysfunction within the solid tumor microenvironment. We dissected CAR-T cell states and their cell-to-cell interactions with the tumor microenvironment across response and tumor progression and identified mechanisms linking CAR-T cell functionality and therapeutic failure. How this study might affect research, practice or policyThis study provides comprehensive mechanistic insights from an immunocompetent model that can be leveraged to identify shared determinants of CAR-T cell functionality in solid tumors and potentially guide the rational development of improved CAR-T cell therapies.

Non-HLA donor-recipient (D-R) genetic mismatches contribute to kidney allograft injury and long-term graft loss, but their clinical use is limited by the unavailability of donor DNA after transplantation. We tested whether non-invasively obtained, recipient-derived samples could be used to infer donor genotype and D-R mismatches. Genomic DNA (g-DNA) of 11 unselected kidney transplant recipients and donors underwent whole-exome sequencing (100x). Additional customized probes were added for intronic coverage (300x) of 55 targeted non-HLA genes of reported clinical relevance. Variants identified from sequencing results were compared with plasma cell-free DNA (cfDNA), urine cell-pellet DNA (U-DNA) obtained from the same recipients. Genome-wide-, exonic-, or non-synonymous exonic- mismatches in transmembrane or secreted proteins, and mismatches within target genes were benchmarked using donor g-DNA to generate mismatch scores for each D-R pair. Within each of these genomic scales of mismatch, U-DNA identified D-R mismatches significantly better than the corresponding cfDNA (P<0.001 for each comparison). U-DNA also identified gene-level mismatches in the LIMS1 gene, and correctly inferred established donor-origin risk alleles, including SHROOM3 and APOL1. Our findings demonstrate proof-of-concept that U-DNA in tandem with recipient genome, can non-invasively infer relevant non-HLA loci/mismatches circumventing the need for the donor genomic DNA.