Design, cohort profile and comparison of the KTD-Innov study: a prospective multidimensional biomarker validation study in kidney allograft rejection.

There is an unmet need for robust and clinically validated biomarkers of kidney allograft rejection. Here we present the KTD-Innov study (ClinicalTrials.gov, NCT03582436), an unselected deeply phenotyped cohort of kidney transplant recipients with a holistic approach to validate the clinical utility of precision diagnostic biomarkers. In 2018-2019, we prospectively enrolled consecutive adult patients who received a kidney allograft at seven French centers and followed them for a year. We performed multimodal phenotyping at follow-up visits, by collecting clinical, biological, immunological, and histological parameters, and analyzing a panel of 147 blood, urinary and kidney tissue biomarkers. The primary outcome was allograft rejection, assessed at each visit according to the international Banff 2019 classification. We evaluated the representativeness of participants by comparing them with patients from French, European, and American transplant programs transplanted during the same period. A total of 733 kidney transplant recipients (64.1% male and 35.9% female) were included during the study. The median follow-up after transplantation was 12.3 months (interquartile range, 11.9-13.1 months). The cumulative incidence of rejection was 9.7% at one year post-transplant. We developed a distributed and secured data repository in compliance with the general data protection regulation. We established a multimodal biomarker biobank of 16,736 samples, including 9331 blood, 4425 urinary and 2980 kidney tissue samples, managed and secured in a collaborative network involving 7 clinical centers, 4 analytical platforms and 2 industrial partners. Patients' characteristics, immune profiles and treatments closely resembled those of 41,238 French, European and American kidney transplant recipients. The KTD-Innov study is a unique holistic and multidimensional biomarker validation cohort of kidney transplant recipients representative of the real-world transplant population. Future findings from this cohort are likely to be robust and generalizable.

The Second International Consensus Guidelines on the Management of BK Polyomavirus in Kidney Transplantation.

BK polyomavirus (BKPyV) remains a significant challenge after kidney transplantation. International experts reviewed current evidence and updated recommendations according to Grading of Recommendations, Assessment, Development, and Evaluations (GRADE). Risk factors for BKPyV-DNAemia and biopsy-proven BKPyV-nephropathy include recipient older age, male sex, donor BKPyV-viruria, BKPyV-seropositive donor/-seronegative recipient, tacrolimus, acute rejection, and higher steroid exposure. To facilitate early intervention with limited allograft damage, all kidney transplant recipients should be screened monthly for plasma BKPyV-DNAemia loads until month 9, then every 3 mo until 2 y posttransplant (3 y for children). In resource-limited settings, urine cytology screening at similar time points can exclude BKPyV-nephropathy, and testing for plasma BKPyV-DNAemia when decoy cells are detectable. For patients with BKPyV-DNAemia loads persisting >1000 copies/mL, or exceeding 10 000 copies/mL (or equivalent), or with biopsy-proven BKPyV-nephropathy, immunosuppression should be reduced according to predefined steps targeting antiproliferative drugs, calcineurin inhibitors, or both. In adults without graft dysfunction, kidney allograft biopsy is not required unless the immunological risk is high. For children with persisting BKPyV-DNAemia, allograft biopsy may be considered even without graft dysfunction. Allograft biopsies should be interpreted in the context of all clinical and laboratory findings, including plasma BKPyV-DNAemia. Immunohistochemistry is preferred for diagnosing biopsy-proven BKPyV-nephropathy. Routine screening using the proposed strategies is cost-effective, improves clinical outcomes and quality of life. Kidney retransplantation subsequent to BKPyV-nephropathy is feasible in otherwise eligible recipients if BKPyV-DNAemia is undetectable; routine graft nephrectomy is not recommended. Current studies do not support the usage of leflunomide, cidofovir, quinolones, or IVIGs. Patients considered for experimental treatments (antivirals, vaccines, neutralizing antibodies, and adoptive T cells) should be enrolled in clinical trials.

Evaluation of an automated platform for the detection of HEV RNA in plasma and stool.

INTRODUCTION: We evaluated the performance of the automated Altostar HEV RNA platform for detecting HEV RNA. METHODS AND RESULTS: Clinical performance was determined by testing 81 plasma samples and 10 fecal samples manually quantified previously with the Realstar RT-PCR assay using the Magnapure instrument for extraction. The assays were concordant for 79/81 plasma samples (97.5%) and 10/10 (100%) fecal samples. The two plasma samples that tested negative with the Altostar assay had a very low HEV RNA concentration (1.6 and 1.4 log10 IU/ml). Quantitative results obtained with the automated platform and the manual workflow were highly correlated (ρ= 0.98, p<0.01). The intra-run and inter-run standard deviation were 0.09 IU/ml and 0.13 IU/ml respectively. The assay was linear from 2 to 6 log IU/ml. The limit of detection determined by Probit analysis with the WHO HEV RNA standard was 7.6 [95% CI: 4.4-52.5] IU/ml. CONCLUSIONS: The Altostar platform enables highly accurate testing for the detection of HEV RNA in stool and the quantification of HEV RNA in plasma. This allowed us to shorten turnaround times and to save time for the technical staff.

Effect of steroid pulses in severe BK virus allograft nephropathy with extensive interstitial inflammation.

INTRODUCTION: As there is no specific antiviral treatment currently available for BK polyomavirus associated nephropathy (BKVAN), its management relies on immunosuppression reduction in kidney transplant patients. Data on efficacy of steroid pulses in this indication are lacking. METHODS: We performed a retrospective monocenter study on 64 patients diagnosed with biopsy-proven BKVAN. Patients within the "pulse group" (n = 37) received IV methylprednisolone 10 mg/kg 3 days consecutively. In the "low dose" steroid group (n = 27), patients were continued oral prednisone 5 mg daily. RESULTS: Mean follow up was 78 months in the steroid pulse group and 56 months in the low dose group (p = 0.15). Mean eGFR values at diagnosis were comparable, as well as other demographic characteristics. Mean BK plasma viral load was higher in "pulse" than in "low dose" steroid group. Pulse group had higher inflammation and tubulitis (p < 0.05). Graft loss reached 57% in the "pulse" group versus 41% in the "low dose" group, p = 0.20. Rejection events were similar. No major adverse event was statistically associated with steroid pulse, including infections, cancer, and de novo diabetes. CONCLUSION: No significant differences were found in the evolution of both groups of patients, despite patients receiving "pulse" steroids were identified as the most severe sharing higher BK viral load and more frequent active lesions on histology.

Characteristics, management, and outcome of tuberculosis after liver transplant: A case series and literature review.

BACKGROUND: Liver transplant recipients are at risk of tuberculosis, which is particularly difficult-to diagnose and to treat in this population. METHODS: Retrospective study of all cases of tuberculosis diagnosed from 2007 to 2022 in the French network of liver transplant sites. RESULTS: Twenty-three liver transplant recipients were diagnosed with tuberculosis (six females, median age 59 years [interquartile range, 54-62]), with a median time lapse of 10 months [5-40.5] after transplant, and 38 days [26-60] after symptoms onset. Primary modes of pathogenesis were latent tuberculosis reactivation (n = 15) and transplant-related transmission (n = 3). Even though most patients with pre-transplant data had risk factors for tuberculosis (11/20), IFN-gamma release assay was performed in only three. Most cases involved extra-pulmonary tuberculosis (20/23, 87 %). With median follow-up of 63 months [24-108], five patients died (22 %), including four tuberculosis-related deaths. CONCLUSIONS: Extrapulmonary tuberculosis is a severe disease in liver transplant recipients. Systematic pre-transplant screening of latent tuberculosis may prevent most of them.

Better Rejection-Free Survival at Three Years in Kidney Transplant Recipients With Model-Informed Precision Dosing of Mycophenolate Mofetil.

The clinical impact of individual dose adjustment of mycophenolate mofetil is still debated, due to conflicting results from randomized clinical trials. This retrospective study aimed to compare 3-year rejection-free survival and adverse effects between adult kidney transplant recipients (KTRs) with or without mycophenolate mofetil model-informed precision dosing (MIPD). MIPD is defined here as mycophenolic acid area under the curve (AUC0-12h ) estimation using a limited sampling strategy, pharmacokinetic models and Bayesian estimators; dose recommendation to reach AUC0-12h = 45 mg.h/L; using a widely used online expert system. The study, nested in two multicenter prospective cohort studies, focused on patients who received a mycophenolate drug and were followed up for 1-3 years. Mycophenolate mofetil MIPD was prescribed as per local practice, on a regular basis, when deemed necessary, or not at all. The MIPD group included 341 KTRs and the control group 392. At 3 years, rejection-free survival was respectively 91.2% and 80.6% (P < 0.001) and the cumulative incidence of rejection 5.08% vs. 12.7% per patient × year (hazard ratio = 0.49 (0.34, 0.71), P < 0.001), corresponding to a 2.5-fold reduction. Significant association with rejection-free survival was confirmed in patients at low or high risk of rejection (P = 0.017 and 0.013) and in patients on tacrolimus, but not on cyclosporine (P < 0.001 and 0.205). The mycophenolate mofetil MIPD group had significantly more adverse effects, but most occurred before the first AUC0-12h , suggesting some may be the reason why MIPD was ordered.

A Machine Learning-Driven Virtual Biopsy System For Kidney Transplant Patients.

In kidney transplantation, day-zero biopsies are used to assess organ quality and discriminate between donor-inherited lesions and those acquired post-transplantation. However, many centers do not perform such biopsies since they are invasive, costly and may delay the transplant procedure. We aim to generate a non-invasive virtual biopsy system using routinely collected donor parameters. Using 14,032 day-zero kidney biopsies from 17 international centers, we develop a virtual biopsy system. 11 basic donor parameters are used to predict four Banff kidney lesions: arteriosclerosis, arteriolar hyalinosis, interstitial fibrosis and tubular atrophy, and the percentage of renal sclerotic glomeruli. Six machine learning models are aggregated into an ensemble model. The virtual biopsy system shows good performance in the internal and external validation sets. We confirm the generalizability of the system in various scenarios. This system could assist physicians in assessing organ quality, optimizing allograft allocation together with discriminating between donor derived and acquired lesions post-transplantation.

Prevention, Diagnosis, Evaluation, and Treatment of Hepatitis C in Chronic Kidney Disease: Synopsis of the Kidney Disease: Improving Global Outcomes 2022 Clinical Practice Guideline.

DESCRIPTION: The Kidney Disease: Improving Global Outcomes (KDIGO) 2022 clinical practice guideline on prevention, diagnosis, evaluation, and treatment of hepatitis C in chronic kidney disease (CKD) is an update of the 2018 guideline from KDIGO. METHODS: The KDIGO Work Group (WG) updated the guideline, which included reviewing and grading new evidence that was identified and summarized. As in the previous guideline, the WG used the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach to appraise evidence and rate the strength of recommendations and used expert judgment to develop recommendations. New evidence led to updating of recommendations in the chapters on treatment of hepatitis C virus (HCV) infection in patients with CKD (Chapter 2), management of HCV infection before and after kidney transplant (Chapter 4), and diagnosis and management of kidney disease associated with HCV infection (Chapter 5). Recommendations in chapters on detection and evaluation of hepatitis C in CKD (Chapter 1) and prevention of HCV transmission in hemodialysis units (Chapter 3) were not updated because of an absence of significant new evidence. RECOMMENDATIONS: The 2022 updated guideline includes 43 graded recommendations and 20 ungraded recommendations, 7 of which are new or modified on the basis of the most recent evidence and consensus among the WG members. The updated guidelines recommend expanding treatment of hepatitis C with sofosbuvir-based regimens to patients with CKD glomerular filtration rate categories G4 and G5, including those receiving dialysis; expanding the donor pool for kidney transplant recipients by accepting HCV-positive kidneys regardless of the recipient's HCV status; and initiating direct-acting antiviral treatment of HCV-infected patients with clinical evidence of glomerulonephritis without requiring kidney biopsy. The update also addresses the use of immunosuppressive regimens in such patients.

Identification of liver transplant biopsy phenotypes associated with distinct liver biological markers and allograft survival.

The intricate association between histologic lesions and circulating antihuman leucocyte antigen donor-specific antibodies (DSA) in liver transplantation (LT) requires further clarification. We conducted a probabilistic, unsupervised approach in a comprehensively well-annotated LT cohort to identify clinically relevant archetypes. We evaluated 490 pairs of LT biopsies with DSA testing from 325 recipients transplanted between 2010 and 2020 across 3 French centers and an external cohort of 202 biopsies from 128 recipients. Unsupervised archetypal analysis integrated all clinico-immuno-histologic parameters of each biopsy to identify biopsy archetypes. The median time after LT was 1.17 (interquartile range, 0.38-2.38) years. We identified 7 archetypes distinguished by clinico-immuno-histologic parameters: archetype #1: severe T cell-mediated rejection (15.9%); #2: chronic rejection with ductopenia (1.8%); #3: architectural and microvascular damages (3.5%); #4: (sub)normal (55.9%); #5: mild T cell-mediated rejection (4.9%); #6: acute antibody-mediated rejection (6.5%); and #7: chronic rejection with DSA (11.4%). Cell infiltrates vary in the archetype. These archetypes were associated with distinct liver biological markers and allograft outcomes. These findings remained consistent when stratified using the patient's age or indications for LT, with good performance in the external cohort (mean highest probability assignment = 0.58, standard deviation ± 0.17). In conclusion, we have identified clinically meaningful archetypes, providing valuable insights into the intricate DSA-histology association, which may help standardize liver allograft pathology classification.

Autoimmune hepatitis recurrence after liver transplantation: "Les jeux sont faits".

Autoimmune hepatitis (AIH) may recur after liver transplantation (LT). The aims of this study were to evaluate the incidence and risk factors for recurrent autoimmune hepatitis (rAIH). A multicenter retrospective French nationwide study, including all patients aged ≥16 transplanted for AIH, with at least 1 liver biopsy 1 year after LT, was conducted between 1985 and 2018. Risk factors for rAIH were identified using a multivariate Cox regression model. Three hundred and forty-four patients were included (78.8% women) with a median age at LT of 43.6 years. Seventy-six patients (22.1%) developed recurrence in a median time of 53.6 months (IQR, 14.1-93.2). Actuarial risk for developing rAIH was 41.3% 20 years after LT. In multivariate analysis, the strongest risk factor for rAIH was cytomegalovirus D+/R- mismatch status (HR=2.0; 95% CI: 1.1-3.6; p =0.03), followed by associated autoimmune condition. Twenty-one patients (27.6% of rAIH patients) developed liver graft cirrhosis after rAIH. Independent risk factors for these severe forms of rAIH were young age at LT, IgG levels >20.7 g/L, and LT in the context of (sub)fulminant hepatitis. Immunosuppression, especially long-term maintenance of corticosteroid therapy, was not significantly associated with rAIH. Recurrence of AIH after LT is frequent and may lead to graft loss. Recurrence is more frequent in young patients with active disease at the time of LT, yet systematic corticosteroid therapy does not prevent it.

Evaluation of two anti-SARS-CoV-2 antibody immunoassays for monitoring patients on pre-exposure prophylaxis.

Pre-exposure prophylaxis (PrEP) is crucial to prevent severe COVID-19 in immunocompromised patients. A reliable method is needed to quantify anti-SARS-CoV-2 antibody levels for personalized monitoring during PrEP. We measured the binding antibody concentrations of 63 immunocompromised patients receiving 300mg or 600mg tixagevimab/cilgavimab on PrEP day and twice during the following 3 months. All blood samples were tested using the Abbott anti-SARS-CoV-2 IgG II Quant assay, the Roche Elecsys anti-SARS-CoV-2 S assay, and live virus-based neutralization assays. The results of the two immunoassays were correlated on day 0, 1 month, and 3 months post-PrEP. Passing-Bablok regression demonstrated higher anti-S concentration values measured with the Roche immunoassay compared to those measured with the Abbott immunoassay. Antibody concentrations were higher after 600 mg tixagevimab/cilgavimab prophylaxis than after 300 mg. The neutralizing antibody titers obtained using the omicron BA.5 and BA.2.75 strains were low. Both automated immunoassays are suitable for monitoring immunocompromised patients on PrEP.

Imlifidase for Kidney Transplantation of Highly Sensitized Patients With a Positive Crossmatch: The French Consensus Guidelines.

Imlifidase recently received early access authorization for highly sensitized adult kidney transplant candidates with a positive crossmatch against an ABO-compatible deceased donor. These French consensus guidelines have been generated by an expert working group, in order to homogenize patient selection, associated treatments and follow-up. This initiative is part of an international effort to analyze properly the benefits and tolerance of this new costly treatment in real-life. Eligible patients must meet the following screening criteria: cPRA ≥ 98%, ≤ 65-year of age, ≥ 3 years on the waiting list, and a low risk of biopsy-related complications. The final decision to use Imlifidase will be based on the two following criteria. First, the results of a virtual crossmatch on recent serum, which shall show a MFI for the immunodominant donor-specific antibodies (DSA) > 6,000 but the value of which does not exceed 5,000 after 1:10 dilution. Second, the post-Imlifidase complement-dependent cytotoxicity crossmatch must be negative. Patients treated with Imlifidase will receive an immunosuppressive regimen based on steroids, rATG, high dose IVIg, rituximab, tacrolimus and mycophenolic acid. Frequent post-transplant testing for DSA and systematic surveillance kidney biopsies are highly recommended to monitor post-transplant DSA rebound and subclinical rejection.

Treatment of donor-specific anti-HLA antibodies-mediated rejection after liver transplantation: A French nationwide retrospective study.

The deleterious effect of donor-specific anti-HLA antibodies (DSA) after liver transplantation (LT) has been increasingly recognized during the past decade. Antibody-mediated rejection (AMR) represents a rare but severe complication in the presence of DSA. However, little is known concerning the treatment of AMR after LT. The nationwide French study aimed to describe LT recipients who received specific treatment of AMR. We performed a multicenter retrospective study on 44 patients who were treated with B-cell targeting agents from January 2008 to December 2020. Median patient age at the time of AMR treatment was 51.6 years (range: 17.9-68.0). AMR was classified as acute (n = 19) or chronic (n = 25). The diagnosis of AMR was made after a median time of 16.8 months (range: 0.4-274.2) after LT. The main therapeutic combination was plasma exchange/rituximab/IVIG (n = 25, 56.8%). The median follow-up after the treatment of AMR was 32 months (range: 1-115). After the treatment, 1-, 5- and 10-year patient and graft survivals were 77%, 55.9%, and 55.9%, and 69.5%, 47.0%, and 47.0%, respectively. Initial total bilirubin (Q1-Q3 vs. Q4) was significantly associated with patient survival (log-rank test, p = 0.005) and graft survival (log-rank test, p = 0.002). After a median follow-up of 21 months (range: 12-107), DSA became undetectable in 15/38 patients (39.5%) with available DSA monitoring. In conclusion, specific treatment of AMR in LT recipients has slowly emerged in France during the past decade and has probably been considered in the most severe patients; this explains the global poor outcome, even if the outcome was favorable in some cases.

Impact of direct antiviral agents for hepatitis C virus -induced liver diseases on registration, waiting list and liver transplant activity in France.

Direct-acting antivirals (DAA) has dramatically improved the prognosis of liver transplantation (LT) candidates for HCV end-stage liver disease (ESLD). We aimed to evaluate the impact of DAA on waiting list (WL) registration and LT activity in France. We evaluated all patients registered to the French WL for HCV ESLD between 2000 and 2018. Timespan was divided into two periods according to DAA availability: 2010-2013 versus 2014-2018. Changes in the indications of LT, outcome on WL were evaluated. Then, we evaluated the activity of LT and outcome for HCV recipients in France. Among 3,173 HCV candidates, registration on WL decreased by 33% between 2013 and 2018. The 1-year waitlist survival increased from 76.9% (95%CI: 74.2%-79.4%) in 2010-2013 to 79.8% (95%CI: 77.2%-82.1%) in 2014-2018 (p < 0.01). Regarding LT activity, the part of HCV ESLD decreased from 26% in 2010 to 16% in 2018. The 1-year graft survival rate in HCV recipients increased from 76.9% (95%CI: 73.7%-79.7%) in 2010-2012 to 84.9% (95%CI: 82.9%-86.7%) in 2013-2018 (p < 0.01). The availability of DAA to treat HCV infection is associated with a significant decrease of registration for LT, death and drop out for worsening condition on the LT. In addition, it has decreased the number of HCV+ LT and improved the 1-year graft survival in France.