Exploring kidney allograft rejection: A proof-of-concept study using spatial transcriptomics

In this proof-of-concept study, spatial transcriptomics combined with public single-cell RNA-sequencing data were used to explore the potential of this technology to study kidney allograft rejection. We aimed to map gene expression patterns within diverse pathological states by examining biopsies classified across non-rejection, T cell-mediated acute rejection, and interstitial fibrosis and tubular atrophy (IFTA). Our results revealed distinct immune cell signatures, including those of T and B lymphocytes, monocytes, mast cells, and plasma cells, and their spatial organization within the renal interstitium. We also mapped chemokine receptors and ligands to study immune-cell migration and recruitment. Finally, our analysis demonstrated differential spatial enrichment of transcription signatures associated with kidney allograft rejection across various biopsy regions. Interstitium regions displayed higher enrichment scores for rejection-associated gene expression patterns than did tubular areas, which had negative scores. This implies that these signatures are primarily driven by processes unfolding in the renal interstitium. Overall, this study highlights the value of spatial transcriptomics for revealing cellular heterogeneity and immune signatures in renal transplant biopsies, and demonstrates its potential for studying the molecular and cellular mechanisms associated with rejection. However, certain limitations must be borne in mind regarding the development and future applications of this technology.

High-dimensional mass cytometry identified circulating natural killer T-cell subsets associated with protection from cytomegalovirus infection in kidney transplant recipients

Cytomegalovirus (CMV) infection is associated with poor kidney transplant outcomes. While innate and adaptive immune cells have been implicated in its prevention, an in-depth characterization of the in vivo kinetics of multiple cell subsets and their role in protecting against CMV infection has not been achieved. Here, we performed high-dimensional immune phenotyping by mass cytometry, and functional assays, on 112 serially collected samples from CMV seropositive kidney transplant recipients. Advanced unsupervised deep learning analysis was used to assess immune cell populations that significantly correlated with prevention against CMV infection and anti-viral immune function. Prior to infection, kidney transplant recipients who developed CMV infection showed significantly lower CMV-specific cell-mediated immune (CMI) frequencies than those that did not. A broad diversity of circulating cell subsets within innate and adaptive immune compartments were associated with CMV infection or protective CMV-specific CMI. While percentages of CMV (tetramer-stained)-specific T cells associated with high CMI responses and clinical protection, circulating CD3+CD8midCD56+ NK-T cells overall strongly associated with low CMI and subsequent infection. However, three NK-T cell subsets sharing the CD11b surface marker associated with CMV protection and correlated with strong anti-viral CMI frequencies in vitro. These data were validated in two external independent cohorts of kidney transplant recipients. Thus, we newly describe the kinetics of a novel NK-T cell subset that may have a protective role in post-transplantation CMV infection. Our findings pave the way to more mechanistic studies aimed at understanding the function of these cells in protection against CMV infection.

European Consensus on the Management of Sensitized Kidney Transplant Recipients: A Delphi Study

An increasing number of sensitized patients awaiting transplantation face limited options, leading to fatalities during dialysis and higher costs. The absence of established evidence highlights the need for collaborative consensus. Donor-specific antibodies (DSA)-triggered antibody-mediated rejection (AMR) significantly contributes to kidney graft failure, especially in sensitized patients. The European Society for Organ Transplantation (ESOT) launched the ENGAGE initiative, categorizing sensitized candidates by AMR risk to improve patient care. A systematic review assessed induction and maintenance regimens as well as antibody removal strategies, with statements subjected to the Delphi methodology. A Likert-scale survey was distributed to 53 European experts (Nephrologists, Transplant surgeons and Immunologists) with experience in kidney transplant recipient care. A rate ≥75% with the same answer was considered consensus. Consensus was achieved in 95.3% of statements. While most recommendations aligned, two statements related to complement inhibitors for AMR prophylaxis lacked consensus. The ENGAGE consensus presents contemporary recommendations for desensitization and immunomodulation strategies, grounded in predefined risk categories. The adoption of tailored, patient-specific measures is anticipated to streamline the care of sensitized recipients undergoing renal allografts. While this approach holds the promise of enhancing transplant accessibility and fostering long-term success in transplantation outcomes, its efficacy will need to be assessed through dedicated studies.

Transient acute kidney injury after chimeric antigen receptor T-cell therapy in patients with hematological malignancies

Background

Acute kidney injury (AKI) occurs in 30% of patients infused with chimeric antigen receptor (CAR) T-cells. The purpose of this study was to identify risk factors and long-term outcomes after AKI in patients who received CAR T-cell therapy.

Methods

Medical records of 115 adult patients with R/R hematological malignancies treated with CD19-targeted CAR T-cells at Vall d'Hebron University Hospital between July 2018 and May 2021. Baseline demographic data including age, gender, ethnicity, body mass index (BMI), and co-morbidities, as well as the type of hematological neoplasia and prior lines of therapy were collected. Laboratory parameters including serum creatinine and whole blood hemoglobin were retrospectively reviewed and values were gathered for days +1, +7, +14, +21, and +28 post-infusion.

Results

A total of 24/115 (21%) patients developed AKI related to CAR T-cell therapy; 6/24 with AKI over chronic kidney disease (CKD). Two patients had AKI in the context of lymphodepleting (LD) chemotherapy and the other 22 after CAR T-cell infusion, starting at day+1 in 3 patients, day+7 in 13 patients, day +14 in 1 patient, day+21 in 2 patients, and day+28 in 3 patients. Renal function was recovered in 19/24 (79%) patients within the first month after infusion. Male gender, CKD, cytokine release syndrome (CRS), and immune effector cell-associated neurotoxicity syndrome (ICANS) were associated with AKI. Male gender, CKD, ICANS grade ≥3 and CRS grade ≥2 were identified as independent risk factors for AKI on multivariable analysis. In terms of the most frequent CAR T-cell related complications, CRS was observed in 95 (82%) patients and ICANS in 33 (29%) patients. Steroids were required in 34 (30%) patients and tocilizumab in 37 (32%) patients. Six (5%) patients were admitted to the intensive care unit (1 for septic shock, 4 for CRS grade ≥2 associated to ICANS grade ≥2, and 1 for CRS grade ≥3). A total of 5 (4.4%) patients died in the first 30 days after CAR T-cell infusion for reasons other than disease progression, including 4 cases of infectious complications and 1 of heart failure.

Conclusion

Our results suggest that AKI is a frequent but mild adverse event, with fast recovery in most patients.

Isatuximab Monotherapy for Desensitization in Highly Sensitized Patients Awaiting Kidney Transplant

SIGNIFICANCE STATEMENT

There is no standardized desensitization regimen for kidney transplant candidates. CD38, expressed by plasma cells, could be targeted for desensitization to deplete plasma cells producing alloantibodies and donor-specific antibodies. Few studies and case reports are available regarding the use of CD38 antibodies for desensitization in patients awaiting kidney transplant. This study shows that isatuximab, a CD38-targeting therapy, was well tolerated in kidney transplant candidates, with a durable decrease in anti-HLA antibodies and partial desensitization activity. The short treatment period and long follow-up of this study allowed for the understanding of the mechanism and timing for any antibody rebound. Isatuximab could be further investigated as an option for adjunct therapy to existing desensitization for patients on the kidney transplant waitlist.

BACKGROUND

Patients with calculated panel reactive antibody (cPRA) ≥80.00%, particularly those with cPRA ≥99.90%, are considered highly sensitized and underserved by the Kidney Allocation System. Desensitization removes circulating reactive antibodies and/or suppresses antibody production to increase the chances of a negative crossmatch. CD38 is expressed highly on plasma cells, thus is a potential target for desensitization.

METHODS

This was an open-label single-arm phase 1/2 study investigating the safety, pharmacokinetics, and preliminary efficacy of isatuximab in patients awaiting kidney transplantation. There were two cohorts, cohorts A and B, which enrolled cPRA ≥99.90% and 80.00% to <99.90%, respectively.

RESULTS

Twenty-three patients (12 cohort A, 11 cohort B) received isatuximab 10 mg/kg weekly for 4 weeks then every 2 weeks for 8 weeks. Isatuximab was well tolerated with pharmacokinetic and pharmacodynamic profiles that indicated similar exposure to multiple myeloma trials. It resulted in decreases in CD38 + plasmablasts, plasma cells, and NK cells and significant reductions in HLA-specific IgG-producing memory B cells. Overall response rate, on the basis of a predefined composite desensitization end point, was 83.3% and 81.8% in cohorts A and B. Most responders had decreases in anti-HLA antibodies that were maintained for 26 weeks after the last dose. Overall, cPRA values were minimally affected, however, with only 9/23 patients (39%) having cPRA decreases to target levels. By study cutoff (median follow-up of 68 weeks), six patients received transplant offers, of which four were accepted.

CONCLUSIONS

In this open-label trial, isatuximab was well tolerated and resulted in a durable decrease in anti-HLA antibodies with partial desensitization activity.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04294459 .

Prospective observational study to validate a next-generation sequencing blood RNA signature to predict early kidney transplant rejection

The objective of this study was to validate the performance of Tutivia, a peripheral blood gene expression signature, in predicting early acute rejection (AR) post-kidney transplant. Recipients of living or deceased donor kidney transplants were enrolled in a nonrandomized, prospective, global, and observational study (NCT04727788). The main outcome was validation of the area under the curve (AUC) of Tutivia vs serum creatinine at biopsy alone, or Tutivia + serum creatinine at biopsy. Of the 151 kidney transplant recipients, the mean cohort age was 53 years old, and 64% were male. There were 71% (107/151) surveillance/protocol biopsies and 29% (44/151) for-cause biopsies, with a 31% (47/151) overall rejection rate. Tutivia (AUC 0.69 [95% CI: 0.59-0.77]) and AUC of Tutivia + creatinine at biopsy (0.68 [95% CI: 0.59-0.77]) were greater than the AUC of creatinine at biopsy alone (0.51.4 [95% CI: 0.43-0.60]). Applying a model cut-off of 50 (scale 0-100) generated a high- and low-risk category for AR with a negative predictive value of 0.79 (95% CI: 0.71-0.86), a positive predictive value of 0.60 (95% CI: 0.45-0.74), and an odds ratio of 5.74 (95% CI: 2.63-12.54). Tutivia represents a validated noninvasive approach for clinicians to accurately predict early AR, beyond the current standard of care.

Prognostic Biomarkers in Kidney Transplantation: A Systematic Review and Critical Appraisal

SIGNIFICANCE STATEMENT

Why are there so few biomarkers accepted by health authorities and implemented in clinical practice, despite the high and growing number of biomaker studies in medical research ? In this meta-epidemiological study, including 804 studies that were critically appraised by expert reviewers, the authors have identified all prognostic kidney transplant biomarkers and showed overall suboptimal study designs, methods, results, interpretation, reproducible research standards, and transparency. The authors also demonstrated for the first time that the limited number of studies challenged the added value of their candidate biomarkers against standard-of-care routine patient monitoring parameters. Most biomarker studies tended to be single-center, retrospective studies with a small number of patients and clinical events. Less than 5% of the studies performed an external validation. The authors also showed the poor transparency reporting and identified a data beautification phenomenon. These findings suggest that there is much wasted research effort in transplant biomarker medical research and highlight the need to produce more rigorous studies so that more biomarkers may be validated and successfully implemented in clinical practice.

BACKGROUND

Despite the increasing number of biomarker studies published in the transplant literature over the past 20 years, demonstrations of their clinical benefit and their implementation in routine clinical practice are lacking. We hypothesized that suboptimal design, data, methodology, and reporting might contribute to this phenomenon.

METHODS

We formed a consortium of experts in systematic reviews, nephrologists, methodologists, and epidemiologists. A systematic literature search was performed in PubMed, Embase, Scopus, Web of Science, and Cochrane Library between January 1, 2005, and November 12, 2022 (PROSPERO ID: CRD42020154747). All English language, original studies investigating the association between a biomarker and kidney allograft outcome were included. The final set of publications was assessed by expert reviewers. After data collection, two independent reviewers randomly evaluated the inconsistencies for 30% of the references for each reviewer. If more than 5% of inconsistencies were observed for one given reviewer, a re-evaluation was conducted for all the references of the reviewer. The biomarkers were categorized according to their type and the biological milieu from which they were measured. The study characteristics related to the design, methods, results, and their interpretation were assessed, as well as reproducible research practices and transparency indicators.

RESULTS

A total of 7372 publications were screened and 804 studies met the inclusion criteria. A total of 1143 biomarkers were assessed among the included studies from blood ( n =821, 71.8%), intragraft ( n =169, 14.8%), or urine ( n =81, 7.1%) compartments. The number of studies significantly increased, with a median, yearly number of 31.5 studies (interquartile range [IQR], 23.8-35.5) between 2005 and 2012 and 57.5 (IQR, 53.3-59.8) between 2013 and 2022 ( P < 0.001). A total of 655 studies (81.5%) were retrospective, while 595 (74.0%) used data from a single center. The median number of patients included was 232 (IQR, 96-629) with a median follow-up post-transplant of 4.8 years (IQR, 3.0-6.2). Only 4.7% of studies were externally validated. A total of 346 studies (43.0%) did not adjust their biomarker for key prognostic factors, while only 3.1% of studies adjusted the biomarker for standard-of-care patient monitoring factors. Data sharing, code sharing, and registration occurred in 8.8%, 1.1%, and 4.6% of studies, respectively. A total of 158 studies (20.0%) emphasized the clinical relevance of the biomarker, despite the reported nonsignificant association of the biomarker with the outcome measure. A total of 288 studies assessed rejection as an outcome. We showed that these rejection studies shared the same characteristics as other studies.

CONCLUSIONS

Biomarker studies in kidney transplantation lack validation, rigorous design and methodology, accurate interpretation, and transparency. Higher standards are needed in biomarker research to prove the clinical utility and support clinical use.

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.

European Society of Organ Transplantation Consensus Statement on Testing for Non-Invasive Diagnosis of Kidney Allograft Rejection

To address the need for improved biomarkers for kidney transplant rejection, European Society of Organ Transplantation (ESOT) convened a dedicated working group comprised of experts in kidney transplant biomarkers to review literature pertaining to clinical and subclinical acute rejection to develop guidelines in the screening and diagnosis of acute rejection that were subsequently discussed and voted on during the Consensus Conference that took place in person in Prague. The findings and recommendations of the Working Group on Molecular Biomarkers of Kidney Transplant Rejection are presented in this article.

Tracking Circulating HLA-Specific IgG-Producing Memory B Cells with the B-Cell ImmunoSpot Assay

Donor-specific antibodies (DSA) against human leukocyte antigen (HLA) molecules are a major risk factor for rejection of transplanted organs (in antibody-mediated rejection [ABMR]), particularly in patients who have prior sensitization or receive insufficient immunosuppression through minimization or noncompliance. These DSA are measured routinely in the serum of patients prior to transplantation mainly using bead-based technologies or cell-based assays. However, the absence of detectable serum DSA does not always reflect the absence of sensitization or histologically defined ABMR, and so it has been proposed that the detection and measurement of memory B cells capable of secreting antibodies against donor HLA antigens could be carried out using B-cell ImmunoSpot, to better inform the degree of immune sensitization of transplant patients prior to as well as after transplantation. Such an assay is described here.

Tacrolimus After rATG and Infliximab Induction Immunosuppression-RIMINI Trial

BACKGROUND

Infliximab selectively targets recently activated effector cells and, as an induction agent, might enable the safe elimination of mycophenolate from maintenance immunosuppression in kidney transplantation.

METHODS

This is a phase II international multicenter open-label single-arm confidence interval (CI)-based clinical trial of the BIO-DrIM EU consortium aimed at assessing the efficacy and safety of rabbit antithymocyte globulin and infliximab induction in kidney transplantation. Sixty-seven primary kidney transplant recipients at low risk (panel-reactive antibodies <20%, no donor-specific antibodies [DSA]) received rabbit antithymocyte globulin (2 × 1.5 mg/kg, postoperative days 0 and 1) and infliximab (5 mg/kg, postoperative day 2), followed by mycophenolate-free tacrolimus-based immunosuppression for 12 mo. The primary endpoint was efficacy failure, defined as a composite of acute rejection, graft loss, or poor graft function (estimated glomerular filtration rate <40 mL/min) at 12 mo and was based on the endpoint of the comparator study. Additionally, a historical propensity-matched control cohort was established.

RESULTS

Primary endpoint occurred in 22 of 67 patients (32.84%), with upper bound of an exact 1-sided 95% CI of 43.47%, which met the predefined criteria (efficacy failure of <40% and upper-bound 95% CI of <50%) and was similar in the historical matched cohort. By 12 mo, 79.1% of patients remained on the study protocol. Lower rates of BK replication (6% versus 22.4%; P  = 0.013) but higher rates of de novo DSAs (11.9% versus 1.5%; P  = 0.039) were observed in the study cohort.

CONCLUSIONS

A similar efficacy of the study immunosuppression regimen to the comparator study and the historical matched cohort was found. However, a higher de novo DSA emergence points to an increased risk of antibody-mediated rejection (NCT04114188).

Cytomegalovirus Cell-Mediated Immunity: Ready for Routine Use?

Utilizing assays that assess specific T-cell-mediated immunity against cytomegalovirus (CMV) holds the potential to enhance personalized strategies aimed at preventing and treating CMV in organ transplantation. This includes improved risk stratification during transplantation compared to relying solely on CMV serostatus, as well as determining the optimal duration of antiviral prophylaxis, deciding on antiviral therapy when asymptomatic replication occurs, and estimating the risk of recurrence. In this review, we initially provide an overlook of the current concepts into the immune control of CMV after transplantation. We then summarize the existent literature on the clinical experience of the use of immune monitoring in organ transplantation, with a particular interest on the outcomes of interventional trials. Current evidence indicates that cell-mediated immune assays are helpful in identifying patients at low risk for replication for whom preventive measures against CMV can be safely withheld. As more data accumulates from these and other clinical scenarios, it is foreseeable that these assays will likely become part of the routine clinical practice in organ transplantation.

How to measure human leukocyte antigen-specific B cells

PURPOSE OF REVIEW

The implementation of highly sensitive immune assays measuring anti-human leukocyte antigen (HLA) antibodies has modified alloimmune risk stratification and diagnosis of rejection. Nonetheless, anti-HLA antibodies represent the downstream effector mechanism of the B-cell response. Better characterizing the cellular components of the humoral immune response (including memory B cells (mBCs) and long-lived plasma cells) could help to further stratify the alloimmune risk stratification and enable discovery of new therapeutic targets. Several tests that characterize HLA-specific mBCs, either functionally or phenotypically, have been developed in the last years, showing promising applications as well as some limitations.

RECENT FINDINGS

Functional assays involving ex vivo polyclonal activation of mBC have been refined to allow the detection of HLA-specific mBC capable of producing anti-HLA Abs, using different and complementary detection platforms such as multiplex Fluorospot and single antigen bead assay on culture supernatants. Detection of circulating HLA-specific B cells by flow cytometry remains hindered by the very low frequency of HLA-specific mBC.

SUMMARY

Technological refinements have allowed the development of tests detecting HLA-specific mBC. Further evaluation of these assays in clinical trials, both for immune risk stratification and to assess treatment efficacy (desensitization strategies, rescue therapies for ABMR) are now urgently needed.

The coexistence of diabetic retinopathy and diabetic nephropathy is associated with worse kidney outcomes

Background

Up to 50-60% of patients with diabetes have non-diabetic kidney disease (NDKD) on kidney biopsy. Diabetic retinopathy (DR) is a microvascular complication of diabetes frequently associated with diabetic nephropathy (DN). The objective of the current study was to investigate the kidney outcomes and survival in patients with biopsy diagnoses of DN and NDKD according to the presence of DR.

Methods

We conducted an observational, multicentre and retrospective study of the pathological findings of renal biopsies from 832 consecutive patients with diabetes from 2002 to 2014 from 18 nephrology departments. The association of DR with kidney replacement therapy (KRT) or survival was assessed by Kaplan-Meier and Cox regression analyses.

Results

Of 832 patients with diabetes and renal biopsy, 768 had a retinal examination and 221/768 (22.6%) had DR. During a follow-up of 10 years, 288/760 (37.9%) patients with follow-up data needed KRT and 157/760 (20.7%) died. The incidence of KRT was higher among patients with DN (alone or with NDKD) and DR [103/175 (58.9%)] than among patients without DR [88/216 (40.7%), P < .0001]. The incidence of KRT was also higher among patients with only NDKD and DR than among those without DR [18/46 (39.1%) versus 79/331 (23.9%), P < .0001]. In multivariate analysis, DR or DN were independent risk factors for KRT {hazard ratio [HR] 2.48 [confidence interval (CI) 1.85-3.31], P < .001}. DN (with or without DR) was also identified as an independent risk factor for mortality [HR 1.81 (CI 1.26-2.62), P = .001].

Conclusions

DR is associated with a higher risk of progression to kidney failure in patients with histological DN and in patients with NDKD.

A prospective controlled, randomized clinical trial of kidney transplant recipients developed personalized tacrolimus dosing using model-based Bayesian Prediction

For three decades, tacrolimus (Tac) dose adjustment in clinical practice has been calculated empirically according to the manufacturer's labeling based on a patient's body weight. Here, we developed and validated a Population pharmacokinetic (PPK) model including pharmacogenetics (cluster CYP3A4/CYP3A5), age, and hematocrit. Our study aimed to assess the clinical applicability of this PPK model in the achievement of Tac Co (therapeutic trough Tac concentration) compared to the manufacturer's labelling dosage. A prospective two-arm, randomized, clinical trial was conducted to determine Tac starting and subsequent dose adjustments in 90 kidney transplant recipients. Patients were randomized to a control group with Tac adjustment according to the manufacturer's labeling or the PPK group adjusted to reach target Co (6-10 ng/ml) after the first steady state (primary endpoint) using a Bayesian prediction model (NONMEM). A significantly higher percentage of patients from the PPK group (54.8%) compared with the control group (20.8%) achieved the therapeutic target fulfilling 30% of the established superiority margin defined. Patients receiving PPK showed significantly less intra-patient variability compared to the control group, reached the Tac Co target sooner (5 days vs 10 days), and required significantly fewer Tac dose modifications compared to the control group within 90 days following kidney transplant. No statistically significant differences occurred in clinical outcomes. Thus, PPK-based Tac dosing offers significant superiority for starting Tac prescription over classical labeling-based dosing according to the body weight, which may optimize Tac-based therapy in the first days following transplantation.

Role of light chain clearance in the recovery of renal function in multiple myeloma: another point of view

BACKGROUND

Acute kidney injury (AKI) in patients with multiple myeloma (MM) requiring renal replacement treatment (RRT) is associated with high morbidity and mortality. Early reduction of serum free light chains (FLC) using both targeted therapy against MM and intensive hemodialysis (IHD) may improve renal outcomes. We evaluated the effectiveness of two different RRT techniques on renal recovery in an MM patient population: standard dialysis procedure vs IHD with either polymethylmethacrylate (PMMA) or hemodiafiltration with endogenous reinfusion (HFR).

METHODS

This was a multicentric retrospective study with severe AKI related to MM, between 2011 and 2018. Twenty-five consecutive patients with AKI secondary to MM requiring RRT were included. Patients that underwent IHD received six dialysis sessions per week during the first 14 days (PMMA vs HFR). All patients were diagnosed with de novo MM or first relapsed MM. Primary outcome was renal recovery defined as dialysis-free at 6 months follow-up.

RESULTS

A total of 25 patients were included. Seventeen patients received IHD and eight standard dialysis. All patients were treated with targeted therapy, 84% bortezomib-based. Of the 25 patients included, 14 (56%) became dialysis independent. We observed a higher proportion of patients who received IHD in the group who recovered kidney function compared with those who remained in HD (92.9% vs 36.4%, P = .007). In our study, the use of IHD to remove FLC had a statistically significant association with renal recovery compared with the standard dialysis group (P = .024).

CONCLUSION

Early reduction of FLC with IHD as an adjuvant treatment along with MM-targeted therapy may exert a positive impact on renal recovery.

Comparison of Three Renal Function Formulas for Ganciclovir/Valganciclovir Dose Individualization in CMV-Infected Solid Organ Transplantation Patients Using a Population Approach

BACKGROUND AND OBJECTIVE

The gold standard treatment of established cytomegalovirus infection or prevention in solid organ transplantation is the intravenous administration of ganciclovir (GCV) or oral administration of valganciclovir (VGCV), both adjusted to the renal function. In both instances, there is a high interindividual pharmacokinetic variability, mainly owing to the wide range of variation of both the renal function and body weight. Therefore, accurate estimation of the renal function is crucial for GCV/VGCV dose optimization. This study aimed to compare three different formulas for estimating the renal function in solid organ transplantation patients with cytomegalovirus infection, for individualizing antiviral therapy with GCV/VGCV, using a population approach.

METHODS

A population pharmacokinetic analysis was performed using NONMEM 7.4. A total of 650 plasma concentrations obtained after intravenous GCV and oral VGCV administrations were analyzed, from intensive and sparse sampling designs. Three different population pharmacokinetic models were built with the renal function given by Cockcroft-Gault, Modification of Diet in Renal Disease, or Chronic Kidney Disease EPIdemiology Collaboration (CKD-EPI) formulas. Pharmacokinetic parameters were allometrically scaled to body weight.

RESULTS

The CKD-EPI formula was identified as the best predictor of between-patient variability in GCV clearance. Internal and external validation techniques showed that the CKD-EPI model had better stability and performed better compared with the others.

CONCLUSIONS

The model based on the more accurate estimation of the renal function with the CKD-EPI formula and body weight as a size metric most used in the clinical practice can refine initial dose recommendations and contribute to GCV and VGCV dose individualization when required in the prevention or treatment of cytomegalovirus infection in solid organ transplantation patients.

The Effect of Intracellular Tacrolimus Exposure on Calcineurin Inhibition in Immediate- and Extended-Release Tacrolimus Formulations

Despite intensive monitoring of whole blood tacrolimus concentrations, acute rejection after kidney transplantation occurs during tacrolimus therapy. Intracellular tacrolimus concentrations could better reflect exposure at the site of action and its pharmacodynamics (PD). Intracellular pharmacokinetic (PK) profile following different tacrolimus formulations (immediate-release (TAC-IR) and extended-release (TAC-LCP)) remains unclear. Therefore, the aim was to study intracellular tacrolimus PK of TAC-IR and TAC-LCP and its correlation with whole blood (WhB) PK and PD. A post-hoc analysis of a prospective, open-label, crossover investigator-driven clinical trial (NCT02961608) was performed. Intracellular and WhB tacrolimus 24 h time-concentration curves were measured in 23 stable kidney transplant recipients. PD analysis was evaluated measuring calcineurin activity (CNA) and simultaneous intracellular PK/PD modelling analysis was conducted. Higher dose-adjusted pre-dose intracellular concentrations (C₀ and C₂₄) and total exposure (AUC_0-24) values were found for TAC-LCP than TAC-IR. Lower intracellular peak concentration (C_max) was found after TAC-LCP. Correlations between C₀, C₂₄ and AUC_0-24 were observed within both formulations. Intracellular kinetics seems to be limited by WhB disposition, in turn, limited by tacrolimus release/absorption processes from both formulations. The faster intracellular elimination after TAC-IR was translated into a more rapid recovery of CNA. An Emax model relating % inhibition and intracellular concentrations, including both formulations, showed an IC₅₀, a concentration to achieve 50% CNA inhibition, of 43.9 pg/million cells.

An automated histological classification system for precision diagnostics of kidney allografts

For three decades, the international Banff classification has been the gold standard for kidney allograft rejection diagnosis, but this system has become complex over time with the integration of multimodal data and rules, leading to misclassifications that can have deleterious therapeutic consequences for patients. To improve diagnosis, we developed a decision-support system, based on an algorithm covering all classification rules and diagnostic scenarios, that automatically assigns kidney allograft diagnoses. We then tested its ability to reclassify rejection diagnoses for adult and pediatric kidney transplant recipients in three international multicentric cohorts and two large prospective clinical trials, including 4,409 biopsies from 3,054 patients (62.05% male and 37.95% female) followed in 20 transplant referral centers in Europe and North America. In the adult kidney transplant population, the Banff Automation System reclassified 83 out of 279 (29.75%) antibody-mediated rejection cases and 57 out of 105 (54.29%) T cell-mediated rejection cases, whereas 237 out of 3,239 (7.32%) biopsies diagnosed as non-rejection by pathologists were reclassified as rejection. In the pediatric population, the reclassification rates were 8 out of 26 (30.77%) for antibody-mediated rejection and 12 out of 39 (30.77%) for T cell-mediated rejection. Finally, we found that reclassification of the initial diagnoses by the Banff Automation System was associated with an improved risk stratification of long-term allograft outcomes. This study demonstrates the potential of an automated histological classification to improve transplant patient care by correcting diagnostic errors and standardizing allograft rejection diagnoses.ClinicalTrials.gov registration: NCT05306795 .

Corrigendum: Enteric Budesonide in Transplant and Native IgA Nephropathy: Real-World Clinical Practice

[This corrects the article DOI: 10.3389/ti.2022.10693.].

Immunosuppressant drugs and quality-of-life outcomes in kidney transplant recipients: An international cohort study (EU-TRAIN)

Introduction: Patient-Reported Outcomes (PRO) integrate a wide range of holistic dimensions that arenot captured within clinical outcomes. Particularly, from induction treatment to maintenance therapy, patient quality-of-life (QoL) of kidney transplant recipients have been sparsely investigated in international settings. Methods: In a prospective, multi-centric cohort study, including nine transplant centers in four countries, we explored the QoL during the year following transplantation using validated elicitation instruments (EQ-5D-3L index with VAS) in a population of kidney transplant patients receiving immunosuppressive therapies. Calcineurin inhibitors (tacrolimus and ciclosporin), IMPD inhibitor (mycophenolate mofetil), and mTOR inhibitors (everolimus and sirolimus) were the standard-of-care (SOC) medications, together with tapering glucocorticoid therapy. We used EQ-5D and VAS data as QoL measures alongside descriptive statistics at inclusion, per country and hospital center. We computed the proportions of patients with different immunosuppressive therapy patterns, and using bivariate and multivariate analyses, assessed the variations of EQ-5D and VAS between baseline (i.e., inclusion Month 0) and follow up visits (Month 12). Results: Among 542 kidney transplant patients included and followed from November 2018 to June 2021, 491 filled at least one QoL questionnaire at least at baseline (Month 0). The majority of patients in all countries received tacrolimus and mycophenolate mofetil, ranging from 90.0% in Switzerland and Spain to 95.8% in Germany. At M12, a significant proportion of patients switched immunosuppressive drugs, with proportion varying from 20% in Germany to 40% in Spain and Switzerland. At visit M12, patients who kept SOC therapy had higher EQ-5D (by 8 percentage points, p < 0.05) and VAS (by 4 percentage points, p < 0.1) scores than switchers. VAS scores were generally lower than EQ-5D (mean 0.68 [0.5-0.8] vs. 0.85 [0.8-1]). Discussion: Although overall a positive trend in QoL was observed, the formal analyses did not show any significant improvements in EQ-5D scores or VAS. Only when the effect of a therapy use was separated from the effect of switching, the VAS score was significantly worse for switchers during the follow up period, irrespective of the therapy type. If adjusted for patient characteristics and medical history (e.g., gender, BMI, eGRF, history of diabetes), VAS and EQ-5D delivered sound PRO measures for QoL assessments during the year following renal transplantation.

Sensitization in transplantation: Assessment of Risk 2022 Working Group Meeting Report

The Sensitization in Transplantation: Assessment of Risk workgroup is a collaborative effort of the American Society of Transplantation and the American Society of Histocompatibility and Immunogenetics that aims at providing recommendations for clinical testing, highlights gaps in current knowledge, and proposes areas for further research to enhance histocompatibility testing in support of solid organ transplantation. This report provides updates on topics discussed by the previous Sensitization in Transplantation: Assessment of Risk working groups and introduces 2 areas of exploration: non-human leukocyte antigen antibodies and utilization of human leukocyte antigen antibody testing measurement to evaluate the efficacy of antibody-removal therapies.

On the clinical relevance of using complete high-resolution HLA typing for an accurate interpretation of posttransplant immune-mediated graft outcomes

Complete and high-resolution (HR) HLA typing improves the accurate assessment of donor–recipient compatibility and pre-transplant donor-specific antibodies (DSA). However, the value of this information to identify de novo immune-mediated graft events and its impact on outcomes has not been assessed. In 241 donor/recipient kidney transplant pairs, DNA samples were re-evaluated for six-locus (A/B/C/DRB1/DQB1+A1/DPB1) HR HLA typing. De novo anti-HLA antibodies were assessed using solid-phase assays, and dnDSA were classified either (1) as per current clinical practice according to three-locus (A/B/DRB1) low-resolution (LR) typing, estimating donor HLA-C/DQ typing with frequency tables, or (2) according to complete six-locus HR typing. The impact on graft outcomes was compared between groups. According to LR HLA typing, 36 (15%) patients developed dnDSA (LR_dnDSA+). Twenty-nine out of 36 (80%) were confirmed to have dnDSA by HR typing (LR_dnDSA+/HR_dnDSA+), whereas 7 (20%) did not (LR_dnDSA+/HR_dnDSA−). Out of 49 LR_dnDSA specificities, 34 (69%) were confirmed by HR typing whereas 15 (31%) LR specificities were not confirmed. LR_dnDSA+/HR_dnDSA+ patients were at higher risk of ABMR as compared to dnDSA− and LR_dnDSA+/HR_dnDSA− (logRank < 0.001), and higher risk of death-censored graft loss (logRank = 0.001). Both LR_dnDSA+ (HR: 3.51, 95% CI = 1.25–9.85) and LR_dnDSA+/HR_dnDSA+ (HR: 4.09, 95% CI = 1.45–11.54), but not LR_dnDSA+/HR_dnDSA− independently predicted graft loss. The implementation of HR HLA typing improves the characterization of biologically relevant de novo anti-HLA DSA and discriminates patients with poorer graft outcomes.

European Guideline for the Management of Kidney Transplant Patients With HLA Antibodies: By the European Society for Organ Transplantation Working Group

This guideline, from a European Society of Organ Transplantation (ESOT) working group, concerns the management of kidney transplant patients with HLA antibodies. Sensitization should be defined using a virtual parameter such as calculated Reaction Frequency (cRF), which assesses HLA antibodies derived from the actual organ donor population. Highly sensitized patients should be prioritized in kidney allocation schemes and linking allocation schemes may increase opportunities. The use of the ENGAGE 5 ((Bestard et al., Transpl Int, 2021, 34: 1005–1018) system and online calculators for assessing risk is recommended. The Eurotransplant Acceptable Mismatch program should be extended. If strategies for finding a compatible kidney are very unlikely to yield a transplant, desensitization may be considered and should be performed with plasma exchange or immunoadsorption, supplemented with IViG and/or anti-CD20 antibody. Newer therapies, such as imlifidase, may offer alternatives. Few studies compare HLA incompatible transplantation with remaining on the waiting list, and comparisons of morbidity or quality of life do not exist. Kidney paired exchange programs (KEP) should be more widely used and should include unspecified and deceased donors, as well as compatible living donor pairs. The use of a KEP is preferred to desensitization, but highly sensitized patients should not be left on a KEP list indefinitely if the option of a direct incompatible transplant exists.

Dual Costimulatory and Coinhibitory Targeting with a Hybrid Fusion Protein as an Immunomodulatory Therapy in Lupus Nephritis Mice Models

Systemic lupus erythematosus is a complex autoimmune disorder mostly mediated by B-cells in which costimulatory signals are involved. This immune dysregulation can cause tissue damage and inflammation of the kidney, resulting in lupus nephritis and chronic renal failure. Given the previous experience reported with CTLA4-Ig as well as recent understanding of the PD-1 pathway in this setting, our group was encouraged to evaluate, in the NZBWF1 model, a human fusion recombinant protein (Hybri) with two domains: CTLA4, blocking the CD28—CD80 costimulatory pathway, and PD-L2, exacerbating the PD-1–PD-L2 coinhibitory pathway. After achieving good results in this model, we decided to validate the therapeutic effect of Hybri in the more severe MRL/lpr model of lupus nephritis. The intraperitoneal administration of Hybri prevented the progression of proteinuria and anti-dsDNA antibodies to levels like those of cyclophosphamide and reduced the histological score, infiltration of B-cells, T-cells, and macrophages and immune deposition in both lupus-prone models. Additionally, Hybri treatment produced changes in both inflammatory-related circulating cytokines and kidney gene expression. To summarize, both in vivo studies revealed that the Hybri effect on costimulatory-coinhibitory pathways may effectively mitigate lupus nephritis, with potential for use as a maintenance therapy.

Impaired antigen-specific B-cell responses after Influenza vaccination in kidney transplant recipients receiving co-stimulation blockade with Belatacept

Emerging data suggest that costimulation blockade with belatacept effectively controls humoral alloimmune responses. However, whether this effect may be deleterious for protective anti-infectious immunity remains poorly understood. We performed a mechanistic exploratory study in 23 kidney transplant recipients receiving either the calcineurin-inhibitor tacrolimus (Tac, n=14) or belatacept (n=9) evaluating different cellular immune responses after influenza vaccination such as activated T follicular Helper (Tfh), plasmablasts and H1N1 hemagglutinin (HA)-specific memory B cells (HA⁺mBC) by flow-cytometry, and anti-influenza antibodies by hemagglutination inhibition test (HI), at baseline and days 10, 30 and 90 post-vaccination. The proportion of CD4+CD54RA-CXCR5+ Tfh was lower in belatacept than Tac patients at baseline (1.86%[1.25-3.03] vs 4.88%[2.40-8.27], p=0.01) and remained stable post-vaccination. At M3, HA⁺mBc were significantly higher in Tac-treated patients (0.56%[0.32-1.49] vs 0.27%[0.13-0.44], p=0.04) and correlated with activated Tfh numbers. When stratifying patients according to baseline HA⁺mBc frequencies, belatacept patients with low HA⁺mBC displayed significantly lower HA⁺mBc increases after vaccination than Tac patients (1.28[0.94-2.4] vs 2.54[1.73-5.70], p=0.04). Also, belatacept patients displayed significantly lower seroprotection rates against H1N1 at baseline than Tac-treated patients (44.4% vs 84.6%) as well as lower seroconversion rates at days 10, 30 and 90 after vaccination (50% vs 0%, 63.6% vs 0%, and 63.6% vs 0%, respectively). We show the efficacy of belatacept inhibiting T-dependent antigen-specific humoral immune responses, active immunization should be highly encouraged before starting belatacept therapy.

Anti-Spike antibodies three months after SARS-CoV-2 mRNA vaccine booster dose in patients on hemodialysis: the prospective SENCOVAC study

Introduction

Patients on hemodialysis are at high-risk for complications derived from coronavirus disease-19 (COVID-19). The present analysis evaluated the impact of a booster vaccine dose and breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections on humoral immunity three months after the booster dose.

Methods

This is a multicentric and prospective study assessing IgG anti-Spike antibodies 6 and 9 months after initial SARS-CoV-2 vaccination in patients on hemodialysis that had also received a booster dose before the 6-month assessment (early booster) or between the 6- and 9-month assessments (late booster). The impact of breakthrough infections, type of vaccine, time from the booster and clinical variables were assessed.

Results

A total of 711 patients (67% male, 67 [20-89] years) were included. Of which, 545 (77%) received an early booster and the rest a late booster. At 6 months, 64 (9%) patients had negative anti-Spike antibody titers (3% of early booster and 29% of late booster patients, p = 0.001). At 9 months, 91% of patients with 6-month negative response had seroconverted and there were no differences in residual prevalence of negative humoral response between early and late booster patients (0.9% vs 0.6%, p = 0.693). During follow-up, 35 patients (5%) developed breakthrough SARS-CoV-2 infection. Antibody titers at 9 months were independently associated to mRNA-1273 booster (p = 0.001), lower time from booster (p = 0.043) and past breakthrough SARS-CoV-2 infection (p&lt;0.001).

Conclusions

In hemodialysis patients, higher titers of anti-Spike antibodies at 9 months were associated to mRNA-1273 booster, lower time from booster and past breakthrough SARS-CoV-2 infection.

Mortality in elderly patients starting hemodialysis program

BACKGROUND

The incidence of older patients over 80 years old with chronic kidney disease who start hemodialysis (HD) program has been increasing in the last decade.

METHODS

We aimed to identify risk factors for morbidity and mortality in patients older than 80 years with end-stage renal disease who started HD. We conducted a retrospective observational study of the Catalan Renal registry (RMRC).

RESULTS

A total of 2833 patients equal or older than 80 years (of 15,137) who started HD between 2002 and 2019 from the RMRC were included in the study. In this group, the first dialysis was performed through an arteriovenous fistula in 44%, percutaneous catheter in 28.2%, and tunneled catheter in 26.6%. Conventional dialysis was used in 65.7% and online HD in 34.3%. The most frequent cause of death was cardiac disease (21.8%), followed by social problems (20.4%) and infections (15.9%). Overall survival in older HD during the first year was 84% versus 91% in younger than 80 years (p < 0.001). Cox regression analysis identified the start of HD in the period 2002-2010, chronic obstructive pulmonary disease (COPD), and the onset of HD through vascular graft depicted as risk factors for first-year mortality after dialysis initiation in patients older than 80 years with end-stage renal disease who started HD.

CONCLUSIONS

In conclusion, patients older than 80 years who started HD program had higher mortality, especially those who presented exacerbation of kidney disease, those with COPD, and those who started with a vascular graft.

Tacrolimus CYP3A Single-Nucleotide Polymorphisms and Preformed T- and B-Cell Alloimmune Memory Improve Current Pretransplant Rejection-Risk Stratification in Kidney Transplantation

Achieving fast immunosuppression blood exposure after kidney transplantation is key to abrogating both preformed and de novo anti-donor humoral and cellular alloresponses. However, while tacrolimus (TAC) is the cornerstone immunosuppressant inhibiting adaptive alloimmunity, its blood exposure is directly impacted by different single-nucleotide polymorphisms (SNPs) in CYP3A TAC-metabolizing enzymes. Here, we investigated how functional TAC-CYP3A genetic variants (CYP3A4*22/CYP3A5*3) influence the main baseline clinical and immunological risk factors of biopsy-proven acute rejection (BPAR) by means of preformed donor-specific antibodies (DSAs) and donor-specific alloreactive T cells (DSTs) in a large European cohort of 447 kidney transplants receiving TAC-based immunosuppression. A total of 70 (15.7%) patients developed BPAR. Preformed DSAs and DSTs were observed in 12 (2.7%) and 227 (50.8%) patients, respectively. According to the different CYP3A4*22 and CYP3A5*3 functional allele variants, we found 4 differential new clusters impacting fasting TAC exposure after transplantation; 7 (1.6%) were classified as high metabolizers 1 (HM1), 71 (15.9%) as HM2, 324 (72.5%) as intermediate (IM), and 45 (10.1%) as poor metabolizers (PM1). HM1/2 showed significantly lower TAC trough levels and higher dose requirements than IM and PM (p < 0.001) and more frequently showed TAC underexposure (<5 ng/ml). Multivariate Cox regression analyses revealed that CYP3A HM1 and IM pharmacogenetic phenotypes (hazard ratio (HR) 12.566, 95% CI 1.99–79.36, p = 0.007, and HR 4.532, 95% CI 1.10–18.60, p = 0.036, respectively), preformed DSTs (HR 3.482, 95% CI 1.99–6.08, p < 0.001), DSAs (HR 4.421, 95% CI 1.63–11.98, p = 0.003), and delayed graft function (DGF) (HR 2.023, 95% CI 1.22–3.36, p = 0.006) independently predicted BPAR. Notably, a significant interaction between T-cell depletion and TAC underexposure was observed, showing a reduction of the BPAR risk (HR 0.264, 95% CI 0.08–0.92, p = 0.037). Such variables except for DSAs displayed a higher predictive risk for the development of T cell-mediated rejection (TCMR). Refinement of pretransplant monitoring by incorporating TAC CYP3A SNPs with preformed DSAs as well as DSTs may improve current rejection-risk stratification and help induction treatment decision-making.

Collapsing Glomerulonephritis in a Kidney Transplant Recipient after mRNA SARS-CoV-2 Vaccination

With the vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), studies are describing cases of glomerulonephritis arising after vaccination. We present the first case of a kidney transplant patient who, after mRNA vaccination against SARS-CoV-2, developed nephrotic proteinuria and renal dysfunction, with a biopsy diagnostic of collapsing glomerulonephritis. No other triggers for this glomerulonephritis were identified. Antibodies against the spike protein were negative, but the patient developed a specific T-cell response. The close time between vaccination and the proteinuria suggests a possible determinant role of vaccination. We should be aware of nephropathies appearing after COVID-19 vaccination in kidney transplant recipients also.

Alloimmune Risk Stratification for Kidney Transplant Rejection

Different types of kidney transplantations are performed worldwide, including biologically diverse donor/recipient combinations, which entail distinct patient/graft outcomes. Thus, proper immunological and non-immunological risk stratification should be considered, especially for patients included in interventional randomized clinical trials. This paper was prepared by a working group within the European Society for Organ Transplantation, which submitted a Broad Scientific Advice request to the European Medicines Agency (EMA) relating to clinical trial endpoints in kidney transplantation. After collaborative interactions, the EMA sent its final response in December 2020, highlighting the following: 1) transplantations performed between human leukocyte antigen (HLA)-identical donors and recipients carry significantly lower immunological risk than those from HLA-mismatched donors; 2) for the same allogeneic molecular HLA mismatch load, kidney grafts from living donors carry significantly lower immunological risk because they are better preserved and therefore less immunogenic than grafts from deceased donors; 3) single-antigen bead testing is the gold standard to establish the repertoire of serological sensitization and is used to define the presence of a recipient's circulating donor-specific antibodies (HLA-DSA); 4) molecular HLA mismatch analysis should help to further improve organ allocation compatibility and stratify immunological risk for primary alloimmune activation, but without consensus regarding which algorithm and cut-off to use it is difficult to integrate information into clinical practice/study design; 5) further clinical validation of other immune assays, such as those measuring anti-donor cellular memory (T/B cell ELISpot assays) and non-HLA-DSA, is needed; 6) routine clinical tests that reliably measure innate immune alloreactivity are lacking.

FC072: Acute Kidney Injury and Chimeric Antigen Receptor (CAR)-T Therapy in Haematologic Neoplasias: The Importance of Kidney Disease

BACKGROUND AND AIMS

Chimeric Antigen Receptor (CAR)-T cell therapy has been a revolutionary treatment for hematological malignancies. Additionally, its potential use in solid tumors such as ovarian, prostate and lung neoplasms is currently being investigated with promising results (1).

The most frequent complications after CAR T-cell therapy include cytokine release syndrome (CRS), neurotoxicity, infections, cytopenia and hypogammaglobulinaemia (2, 3, 4, 5). Acute kidney injury (AKI) occurs between 20–30%, mostly associated with cytokine release syndrome (CRS), hydroelectrolyte disorders and tumor lysis syndrome (TLS). The purpose of this study was to determine the demographics, laboratory results and clinical evolution of patients who have received CAR-T cell therapy to identify risk factors associated with AKI and long-term outcomes in these patients.

METHOD

We performed a retrospective review of the medical records of 115 patients with haematological neoplasms who received CD19-targeted CAR T-cell therapy at Vall d'Hebron Hospital between July 2018 and May 2021. Clinical and laboratory results of the first 60 days post-infusion were systematically examined and data was collected at the following days: +1, +7, +14, +21, +28 and +60. AKI was defined as the Kidney Disease Improving Global Outcomes (KDIGO) criteria: grade 1, 1.5 to &lt;2-fold of baseline; grade 2, 2 to &lt; 3-fold of baseline; and grade 3, ≥3-fold of baseline. Firstly, the sample was divided into two groups: patients with kidney injury and those without in order to identify risk factors for AKI. Secondly, actuarial survival curves were estimated using the Kaplan–Meier method.

RESULTS

A total of 24 (20.9%) of the 115 patients presented AKI after CAR-T cell therapy infusion. AKI was diagnosed by day +1 post-infusion in 3 (2.6%) patients, by day +7 in 13 (11.3%) patients, by day +14 in 1 (0.9%) patient, by day +21 in 2 (1.7%) patients, by day +28 in 2 patients (1.7%), by day +60 in 1 (0.9%) patient and 2 (1.7%) patients during the fludarabine and cyclophosphamide conditioning chemotherapy. Nineteen (79.2%) patients recovered kidney function within the first month after CAR-T infusion. Mean age was 61 ±14.8 years and 66.1% were male. Demographic and clinical characteristics are shown in Table 1 (AKI patients and non-AKI patients). Briefly, hypertension was present in 37.4% of patients, diabetes in 7.8%, chronic kidney disease in 13.9% and cardiovascular disease in 5.2%. Haematological neoplasms include diffuse large B-cell lymphoma (90.5%), B-cell acute lymphoblastic leukemia (5.2%), mantle lymphoma (3.5%) and primary mediastinal large B-cell lymphoma (0.68%). Among the types of CAR-T cell therapy, patients received tisagenlecleucel (49.6%), investigational products (27.8%), axicabtagen ciloleucelin (20%) and brexucabtagene autoleucel (2.6%). The most frequent complications were CRS (72.2%), febrile neutropenia (67%) and neurotoxicity (16.5%). Thirty-one (27%) patients required tocilizumab for CRS grade ≥ 2. A total of 5.2% of patients were admitted to the intensive care unit and 31.3% died. In the bivariate analysis, male sex, types of CAR-T cell therapy infused, and neurotoxicity were associated with AKI. Only male sex (1.26–21.9; P 0.23) and neurotoxicity (2.15–70.6; P 0.005) were identified as risk factors for AKI in multivariable analysis. In the actuarial survival analysis, levels of hemoglobin, creatinine, sodium and reactive C protein in day + 1 and in day +28 showed no statistically significant differences for mortality (Table 2).

CONCLUSION

CAR-T cell therapy has shown beneficial results in haematologic malignancies. In our study, 20.9% of patients developed AKI, especially in the first week of the CAR-T infusion. The majority of patients, a total of 79.2% of patients recovered kidney function within the first 28 days post-treatment, suggesting that AKI is a frequent but mild disease with a fast recovery in patients treated with CAR-T cells.

MO1017: Induction Immunosuppression and Outcome in Early Kidney Transplant Recipients with Covid-19

BACKGROUND AND AIMS

COVID-19 in kidney transplants has a high risk of complications and mortality, especially in older recipients diagnosed during the early period after transplantation. Management of immunosuppression has been challenging during the pandemic. We investigated the impact of induction immunosuppression, either basiliximab or thymoglobulin, on the clinical evolution of kidney transplants developing COVID-19 during the early period after transplantation.

METHOD

Kidney transplant recipients with &lt;6 months with a functioning graft diagnosed of COVID-19 from the initial pandemic outbreak (March 2020) until 31 July 2021 from different Spanish centres participating in a nationwide registry.

RESULTS

A total of 127 patients from 17 Spanish centres developed COVID-19 during the first 6 months after transplantation, 73 (57.5%) received basiliximab and 54 (42.5%) thymoglobulin. Demographics were not different between groups, but patients receiving thymoglobulin were more sensitized (cPRA of 32.7% ± 40.8% versus 5.6% ± 18.5%) and more frequently re-transplanted (30% versus 4%). Recipients older than 65 years treated with thymoglobulin showed the highest rate of acute respiratory distress syndrome [64.7% versus 37.1% for older recipients receiving thymoglobulin and basiliximab (P &lt; .05), and 23.7% and 18.9% for young recipients receiving basiliximab and thymoglobulin (P &gt; .05)] and the poorest survival [mortality rate of 64.7% and 42.9% for older recipients treated with thymoglobulin and basiliximab, respectively (P &lt; .05), and 8.1% and 10.5% for young recipients treated with thymoglobulin and basiliximab (P &gt; .05)]. Older recipients treated with thymoglobulin showed the poorest survival in the Cox's regression model adjusted for comorbidities.

CONCLUSION

Thymoglobulin should be used with caution in older recipients during the present pandemic era.

MO631: Diabetic Retinopathy and/or Diabetic Nephropathy Confers A Worse Renal Prognosis

BACKGROUND AND AIMS

Around 50%–60% lesions of non-diabetic nephropathy (NDN) have been identified in patients with diabetes and renal biopsy. NDN patients have a better renal prognosis and survival. Diabetic retinopathy (DR) is a microvascular complication of diabetes frequently associated with diabetic nephropathy (DN). The objective of the work is to study the renal prognosis and survival of patients with DN with or without DR.

METHOD

Retrospective, observational, multicenter study of the pathological results of diabetic patients with renal biopsy was undertaken. A total of 18 Spanish centers have participated.

RESULTS

Cohort of 832 patients: 621 men (74.6%), median age 61.7 ± 12.8 years, median creatinine 2.8 ± 2.2 mg/dL and proteinuria 2.7 (1.2–5.4) g/24 h. Of them, 26.6% (n = 221) presented DR, 18.8% (n = 156) peripheral vasculopathy and 17.7% (n = 147) ischemic heart disease.

On biopsy, 39.5% (n = 329) of patients had DN, 413 (49.6%) NDN and 90 (10.8%) mixed forms. We evidenced more DR in the DN group compared with the other two groups (44.1% versus 11.1% in NDN and 33.3% in mixed forms). Regarding renal prognosis, 58.9% (n = 109) of patients with DR and DN and mixed forms required RRT versus 40.7% (n = 88) of patients without DR. A total of 39.1% (n = 18) of patients with DR and NDN required renal replacement therapy (RRT) versus 23.9% (n = 79) of patients without DR. Regarding mortality, 28.6% (n = 50) of patients with DR and DN or mixed forms died during the follow-up versus 22.7% (n = 49) of patients without DR. A total of 15.2% (n = 7) of patients with DR and NDN died and 15.4% (n = 51) of patients without DR.

In survival analysis (Kaplan—Meier curves), patients with DR had worse renal prognosis (P &lt; 0.001), patients with DN (P &lt; 0.001) and patients with DR and/or DN and mixed forms (P = 0.02). Cox regression analysis identified as independent risk factors of RRT: age (OR 1.014;1.025–1.004, P = 0.006), creatinine (OR 1.262; 1.217–1.309; P &lt; 0.001), proteinuria (OR 1.057; 1.03–1.085; P &lt; 0.001), DR (OR 1.359; 1.007–1.833; P = 0.045), DR and/or DN (OR 1.59; 2.42–1.04; P = 0.033) and DN (OR1.489; 1.05–2.11; P = 0.026).

CONCLUSION

The presence of DR and/or DN confers a worse renal prognosis. The diagnosis of diabetic microangiopathy in terms of retinopathy and/or diabetic nephropathy is crucial since it confers a worse renal prognosis indicating patients at risk of progression to end-stage renal disease.

FC 107: Development and Validation of a Machine Learning-Based Virtual Biopsy System in Kidney Transplant Patients

BACKGROUND AND AIMS

Graphical Abstract

In kidney transplantation, day-zero biopsies are used to assess organ quality and discriminate lesions inherited from the donor or acquired after transplantation. However, many centres worldwide do not perform those biopsies which remain invasive, costly and may delay the transplant procedure. We aimed to develop and validate a noninvasive virtual biopsy system.

METHOD

A total of 17 centres were included from Europe, North America and Australia from 2000 to 2019. Candidate predictors were assessed following a prespecified protocol. Outcome measures were the day-zero biopsy lesions (Banff classification) including CV, AH, IFTA scores and % of sclerotic glomeruli. Six machine learning models were developed and their performances were assessed.

RESULTS

A total of 12 992 day-zero biopsies were included. Eleven parameters were used to build the classifiers, including donor age, kidney function, hypertension, BMI, proteinuria, diabetes, sex, donor type, cause of death and Hep-C status. The ensemble models (random forests, neural networks, gradient boosting, extreme gradient boosting tree, linear discriminant analysis, and naive Bayes) showed multi-AUC of 0.738, 0.817 and 0.788 for prediction of CV, AH and IFTA scores, and a good performance for predicting glomerulosclerosis (mean absolute error, MAE = 4.766). We confirmed the robustness and generalizability in multiple clinical scenarios and subpopulations and built an online interface for clinicians: https://transplant-pred/Virtual_Biopsy.

CONCLUSION

We developed and validated the first virtual biopsy system that enables the prediction of day-zero biopsy, based on routinely collected parameters. This can assist clinicians in assessing allograft quality, discrimination of donor derived versus acquired lesions after transplantation and prevent overdiagnosis of calcineurin inhibitor (CNI) toxicity.

Induction immunosuppression and outcome in kidney transplant recipients with early COVID-19 after transplantation

COVID-19 in kidney transplants has a high risk of complications and mortality, especially in older recipients diagnosed during the early period after transplantation. Management of immunosuppression has been challenging during the pandemic. We investigated the impact of induction immunosuppression, either basiliximab or thymoglobulin, on the clinical evolution of kidney transplants developing COVID-19 during the early period after transplantation. Kidney transplant recipients with less than 6 months with a functioning graft diagnosed of COVID-19 from the initial pandemic outbreak (March 2020) until July 31st, 2021 from different Spanish centers participating in a nationwide registry. A total of 127 patients from 17 Spanish centers developed COVID-19 during the first 6 months after transplantation, 73 (57.5%) received basiliximab and 54 (42.5%) thymoglobulin. Demographics were not different between groups but patients receiving thymoglobulin were more sensitized (cPRA of 32.7±40.8% vs. 5.6±18.5%) and were more frequently re-transplants (30% vs. 4%). Recipients older than 65 years treated with thymoglobulin showed the highest rate of acute respiratory distress syndrome (64.7% vs. 37.1% for older recipients receiving thymoglobulin and basiliximab [p&lt;0.05], and 23.7% and 18.9% for young recipients receiving basiliximab and thymoglobulin [p&gt;0.05]) and the poorest survival (mortality rate of 64.7% and 42.9% for older recipients treated with thymoglobulin and basiliximab, respectively [p&lt;0.05], and 8.1% and 10.5% for young recipients treated with thymoglobulin and basiliximab [p&gt;0.05]). Older recipients treated with thymoglobulin showed the poorest survival in the Cox's regression model adjusted for comorbidities. Thus, thymoglobulin should be used with caution in older recipients during the present pandemic era.

Safety of Obtaining an Extra Biobank Kidney Biopsy Core

Background and objectives: Kidney biopsy (KB) is the “gold standard” for the diagnosis of nephropathies and it is a diagnostic tool that presents a low rate of complications. Nowadays, biobank collections of renal tissue of patients with proven renal pathology are essential for research in nephrology. To provide enough tissue for the biobank collection, it is usually needed to obtain an extra kidney core at the time of kidney biopsy. The objective of our study is to evaluate the complications after KB and to analyze whether obtaining an extra core increases the risk of complications. Material and methods: Prospective observational study of KBs performed at Vall d’Hebron Hospital between 2019 and 2020. All patients who accepted to participate to our research biobank of native kidney biopsies were included to the study. Clinical and laboratory data were reviewed and we studied risk factors associated with complications. Results: A total of 221 patients were included, mean age 56.6 (±16.8) years, 130 (58.8%) were men, creatinine was 2.24 (±1.94) mg/dL, proteinuria 1.56 (0.506–3.590) g/24 h, hemoglobin 12.03 (±2.3) g/dL, INR 0.99 (±0.1), and prothrombin time (PT) 11.86 (±1.2) s. A total of 38 patients (17.2%) presented complications associated with the procedure: 13.1% were minor complications, 11.3% (n = 25) required blood transfusion, 1.4% (n = 3) had severe hematomas, 2.3% (n = 5) required embolization, and 0.5% (n = 1) presented arterio-venous fistula. An increased risk for complication was independently associated with obtaining a single kidney core (vs. 2 and 3 cores) (p = 0.021). Conclusions: KB is an invasive and safe procedure with a low percentage of complications. Obtaining an extra kidney core for research does not increase the risk of complications during the intervention, which remains low in concordance with previously published reports.

A Prospective Multicenter Trial to Evaluate Urinary Metabolomics for Non-invasive Detection of Renal Allograft Rejection (PARASOL): Study Protocol and Patient Recruitment

Background: In an earlier monocentric study, we have developed a novel non-invasive test system for the prediction of renal allograft rejection, based on the detection of a specific urine metabolite constellation. To further validate our results in a large real-world patient cohort, we designed a multicentric observational prospective study (PARASOL) including six independent European transplant centers. This article describes the study protocol and characteristics of recruited better patients as subjects.

Methods: Within the PARASOL study, urine samples were taken from renal transplant recipients when kidney biopsies were performed. According to the Banff classification, urine samples were assigned to a case group (renal allograft rejection), a control group (normal renal histology), or an additional group (kidney damage other than rejection).

Results: Between June 2017 and March 2020, 972 transplant recipients were included in the trial (1,230 urine samples and matched biopsies, respectively). Overall, 237 samples (19.3%) were assigned to the case group, 541 (44.0%) to the control group, and 452 (36.7%) samples to the additional group. About 65.9% were obtained from male patients, the mean age of transplant recipients participating in the study was 53.7 ± 13.8 years. The most frequently used immunosuppressive drugs were tacrolimus (92.8%), mycophenolate mofetil (88.0%), and steroids (79.3%). Antihypertensives and antidiabetics were used in 88.0 and 27.4% of the patients, respectively. Approximately 20.9% of patients showed the presence of circulating donor-specific anti-HLA IgG antibodies at time of biopsy. Most of the samples (51.1%) were collected within the first 6 months after transplantation, 48.0% were protocol biopsies, followed by event-driven (43.6%), and follow-up biopsies (8.5%). Over time the proportion of biopsies classified into the categories Banff 4 (T-cell-mediated rejection [TCMR]) and Banff 1 (normal tissue) decreased whereas Banff 2 (antibody-mediated rejection [ABMR]) and Banff 5I (mild interstitial fibrosis and tubular atrophy) increased to 84.2 and 74.5%, respectively, after 4 years post transplantation. Patients with rejection showed worse kidney function than patients without rejection.

Conclusion: The clinical characteristics of subjects recruited indicate a patient cohort typical for routine renal transplantation all over Europe. A typical shift from T-cellular early rejections episodes to later antibody mediated allograft damage over time after renal transplantation further strengthens the usefulness of our cohort for the evaluation of novel biomarkers for allograft damage.

OUP accepted manuscript

Novel coronavirus disease infection (coronavirus disease 2019, COVID-19) was declared a global pandemic in March 2020 and since then has become a major public health problem. The prevalence of COVID-19 infection and acute kidney injury (AKI) is variable depending on several factors such as race/ethnicity and severity of illness. The pathophysiology of renal involvement in COVID-19 infection is not entirely clear, but it could be in part explained by the viral tropism in the kidney parenchyma. AKI in COVID-19 infection can be either by direct invasion of the virus or as a consequence of immunologic response. Diverse studies have focused on the effect of COVID-19 on glomerulonephritis (GN) patients or the ‘novo’ GN; however, the effect of COVID-19 in acute tubulointerstitial nephritis (ATIN) has been scarcely studied. In this article, we present five cases with different spectrums of COVID-19 infection and ATIN that may suggest that recent diagnosis of ATIN is accompanied by a worse clinical prognosis in comparison with long-term diagnosed ATIN.

COVID-19 in Patients with Glomerular Disease: Follow-Up Results from the IRoc-GN International Registry

Background

The acute and long-term effects of severe acute respiratory syndrome coronavirus 2 infection in individuals with GN are still unclear. To address this relevant issue, we created the International Registry of COVID-19 infection in GN.

Methods

We collected serial information on kidney-related and -unrelated outcomes from 125 GN patients (63 hospitalized and 62 outpatients) and 83 non-GN hospitalized patients with coronavirus disease 2019 (COVID-19) and a median follow-up period of 6.4 (interquartile range 2.3-9.6) months after diagnosis. We used logistic regression for the analyses of clinical outcomes and linear mixed models for the longitudinal analyses of eGFR. All multiple regression models were adjusted for age, sex, ethnicity, and renin-angiotensin-aldosterone system inhibitor use.

Results

After adjustment for pre-COVID-19 eGFR and other confounders, mortality and AKI did not differ between GN patients and controls (adjusted odds ratio for AKI=1.28; 95% confidence interval [CI], 0.46 to 3.60; P=0.64). The main predictor of AKI was pre-COVID-19 eGFR (adjusted odds ratio per 1 SD unit decrease in eGFR=3.04; 95% CI, 1.76 to 5.28; P<0.001). GN patients developing AKI were less likely to recover pre-COVID-19 eGFR compared with controls (adjusted 6-month post-COVID-19 eGFR=0.41; 95% CI, 0.25 to 0.56; times pre-COVID-19 eGFR). Shorter duration of GN diagnosis, higher pre-COVID-19 proteinuria, and diagnosis of focal segmental glomerulosclerosis or minimal change disease were associated with a lower post-COVID-19 eGFR.

Conclusions

Pre-COVID-19 eGFR is the main risk factor for AKI regardless of GN diagnosis. However, GN patients are at higher risk of impaired eGFR recovery after COVID-19-associated AKI. These patients (especially those with high baseline proteinuria or a diagnosis of focal segmental glomerulosclerosis or minimal change disease) should be closely monitored not only during the acute phases of COVID-19 but also after its resolution.

Deciphering transplant outcomes of expanded kidney allografts donated after controlled circulatory death in the current transplant era. A call for caution

Outcomes of kidney transplantation (KT) after controlled circulatory death (cDCD) with highly expanded criteria donors (ECD) and recipients have not been thoroughly evaluated. We analyzed in a multicenter cohort of 1161 consecutive KT, granular baseline donor and recipient factors predicting transplant outcomes, selected by bootstrapping and Cox proportional hazards, and were validated in a contemporaneous European KT cohort (n = 1585). 74.3% were DBD and 25.7% cDCD-KT. ECD-KT showed the poorest graft survival rates, irrespective of cDCD or DBD (log-rank < 0.001). Besides standard ECD classification, dialysis vintage, older age, and previous cardiovascular recipient events together with low class-II-HLA match, long cold ischemia time and combining a diabetic donor with a cDCD predicted graft loss (C-Index 0.715, 95% CI 0.675-0.755). External validation showed good prediction accuracy (C-Index 0.697, 95%CI 0.643-0.741). Recipient older age, male gender, dialysis vintage, previous cardiovascular events, and receiving a cDCD independently predicted patient death. Benefit/risk assessment of undergoing KT was compared with concurrent waitlisted candidates, and despite the fact that undergoing KT outperformed remaining waitlisted, remarkably high mortality rates were predicted if KT was undertaken under the worst risk-prediction model. Strategies to increase the donor pool, including cDCD transplants with highly expanded donor and recipient candidates, should be performed with caution.

SARS-CoV-2-specific serological and functional T cell immune responses during acute and early COVID-19 convalescence in solid organ transplant patients

The description of protective humoral and T cell immune responses specific against SARS-CoV-2 has been reported among immunocompetent (IC) individuals developing COVID-19 infection. However, its characterization and determinants of poorer outcomes among the at-risk solid organ transplant (SOT) patient population have not been thoroughly investigated. Cytokine-producing T cell responses, such as IFN-γ, IL-2, IFN-γ/IL-2, IL-6, IL-21, and IL-5, against main immunogenic SARS-CoV-2 antigens and IgM/IgG serological immunity were tracked in SOT (n = 28) during acute infection and at two consecutive time points over the following 40 days of convalescence and were compared to matched IC (n = 16) patients admitted with similar moderate/severe COVID-19. We describe the development of a robust serological and functional T cell immune responses against SARS-CoV-2 among SOT patients, similar to IC patients during early convalescence. However, at the infection onset, SOT displayed lower IgG seroconversion rates (77% vs. 100%; p = .044), despite no differences on IgG titers, and a trend toward decreased SARS-CoV-2-reactive T cell frequencies, especially against the membrane protein (7 [0-34] vs. 113 [15-245], p = .011, 2 [0-9] vs. 45 [5-74], p = .009, and 0 [0-2] vs. 13 [1-24], p = .020, IFN-γ, IL-2, and IFN-γ/IL-2 spots, respectively). In summary, our data suggest that despite a certain initial delay, SOT population achieve comparable functional immune responses than the general population after moderate/severe COVID-19.