OPTN/SRTR 2021 Annual Data Report: Kidney

Clinical events and healthcare resource utilization associated with neutropenia and leukopenia among adult kidney transplant recipients receiving valganciclovir

BACKGROUND

Cytomegalovirus (CMV) prophylaxis with valganciclovir and ganciclovir is associated with elevated neutropenia and leukopenia risk in kidney transplant recipients, although the impact of these events on healthcare resource utilization (HCRU) and clinical outcomes is unclear.

AIM

To quantify clinical events and HCRU associated with neutropenia and leukopenia among adults receiving valganciclovir and/or ganciclovir post-kidney transplantation.

METHODS

Adult kidney transplant recipients receiving valganciclovir and/or ganciclovir prophylaxis were identified in the TriNetX database from 2012 to 2021. Patient characteristics were evaluated in the 1-year period pre-first transplant. HCRU and adjusted event rates per person-year were evaluated in follow-up year 1 and years 2-5 after first kidney transplantation among cohorts with vs without neutropenia and/or leukopenia.

RESULTS

Of 15398 identified patients, the average age was 52.39 years and 58.70% were male. Patients with neutropenia and/or leukopenia had greater risk of clinical events for CMV-related events, opportunistic infections, use of granulocyte colony stimulating factor, and hospitalizations (relative risk > 1 in year 1 and years 2-5). Patients with vs without neutropenia and/or leukopenia had higher HCRU in year 1 and years 2-5 post kidney transplantation, including the mean number of inpatient admissions (year 1: 3.47 vs 2.76; years 2-5: 2.70 vs 2.29) and outpatient visits (48.97 vs 34.42; 31.73 vs 15.59, respectively), as well as the mean number of labs (1654.55 vs 1182.27; 622.37 vs 327.89).

CONCLUSION

Adults receiving valganciclovir and/or ganciclovir prophylaxis post-kidney transplantation had greater risk of neutropenia and/or leukopenia, which were associated with higher clinical event rates and HCRU up to 5 years post-transplantation. These findings suggest the need for alternative prophylaxis options with lower myelosuppressive effects to improve patient outcomes.

Appraisal of Impact of Race-Neutral Estimated Glomerular Filtration Rate Waiting Time Modification on Transplant Wait Time and Outcomes for Black Kidney Candidates: Importance of Transplant Readiness on the Waitlist

BACKGROUND

In July 2022, the Organ Procurement Transplant Network mandated race-neutral estimated glomerular filtration rate (eGFR) calculations when evaluating kidney transplantation (KT) candidates, replacing historic race-based estimates. This modification also required transplant programs to identify KT candidates on their waitlist who would have benefitted from an earlier waitlist qualification date using race-neutral calculations.

STUDY DESIGN

This retrospective study analyzed Black patients listed for KT at our center between 2000 and 2023, recalculating their eGFR using race-neutral formulas. KT recipients with modified wait times (N = 26) were compared with 2 control groups: Black recipients without modifications (N = 21) and non-Black recipients (N = 89). Postoperative outcomes, including complications and readmission rates, were analyzed across groups.

RESULTS

Of 126 Black patients evaluated, 60.3% qualified for wait time modifications, with a median gain of 570 days (1.6 years) per patient, totaling 62,057 days (180.7 years). Within 6 months of receiving additional time, 26 patients (34%) were transplanted, mostly from deceased donors (92%) with a median kidney donor profile index of 66%. Black KT recipients with modifications had significantly higher BMI, diabetes, and peripheral vascular disease compared with controls. Readmission rates were higher among Black KT recipients with modifications, although no significant differences in graft loss or mortality were observed.

CONCLUSIONS

Race-neutral eGFR recalculations substantially improved Black KT candidates' ability to receive a KT, addressing historical disparities in KT. However, higher comorbidities and readmissions among these patients suggest the need for thorough transplant readiness evaluations before waitlist activation.

Blood Gene Expression Profiling and Donor-derived Cell-free DNA to Noninvasively Diagnose Clinical and Subclinical Kidney Transplant Rejection: A Real-life Appraisal Study

BACKGROUND

Peripheral blood biomarkers aim to noninvasively diagnose kidney allograft rejection, but most lack robust independent validation. TruGraf is intended to exclude subclinical cellular rejection (TCMR), whereas donor-derived cell-free DNA Viracor-TRAC has proven value in excluding antibody-mediated rejection (AMR). We aim to validate both biomarkers for accurate rejection diagnosis in a real-world clinical setting.

METHODS

We prospectively included 230 unselected, consecutive kidney transplants from 6 centers undergoing for-cause and protocol biopsies with paired blood samples from December 2021 to 2022. TruGraf and Viracor-TRAC were blindly run by a central laboratory.

RESULTS

The incidence of rejection was 22.6% (17.3% surveillance; 27% for-cause biopsies). Inflammation was associated with higher TRAC levels, with AMR/mixed and microvascular inflammation (MVI) showing the highest levels ( P  < 0.05). TruGraf did not associate with any specific allograft injury. No biomarkers, individually or combined, accurately diagnosed any rejection (area under the receiver operating characteristic curve [AUROC] < 0.65). However, high TRAC levels, when combined with DSA in for-cause biopsies, predicted AMR/mixed rejection or MVI (AUROC = 0.817; P  < 0.001), outperforming serum creatinine and DSA (AUROC < 0.65).

CONCLUSIONS

In this large, prospective, observational real-life study, we were unable to validate TruGraf and TRAC to diagnose rejection but found a useful context of use for TRAC to noninvasively diagnose AMR/mixed or MVI in conjunction with DSA in dysfunctioning graft.

Back-table intra-arterial administration of C1 esterase inhibitor to deceased donor kidney allografts improves posttransplant allograft function: Results of a randomized double-blind placebo-controlled clinical trial

Ischemia-reperfusion injury commonly causes delayed graft function (DGF) after kidney transplantation and is associated with poorer graft function and lower allograft survival. Activation of the lectin complement pathway is one mediator of ischemia-reperfusion injury. In this randomized double-blind placebo-controlled pilot study, we tested whether preimplantation intragraft administration of C1 esterase inhibitor (C1INH, a lectin/classical pathway inhibitor) into deceased donor organs improves graft function and/or reduces DGF. Forty patients were randomized 1:1 to receive allografts treated with 500 units C1INH or placebo (normal saline) into the transplant renal artery during back-table preparation. We observed no effect on DGF, but recipients of C1INH-treated allografts showed higher estimated glomerular filtration rate than recipients of placebo at 6 months (C1INH median: 55 mL/min/1.73 m2, interquartile range [IQR]: 42-63; placebo median: 39 mL/min/1.73 m2, IQR: 34-50; P = .02) and 30 months (C1INH median: 54 mL/min/1.73 m2, IQR: 47-66; placebo median: 43 mL/min/1.73 m2, IQR 38-51; P = .03), with no differences in adverse events. Analysis of postreperfusion biopsies showed positive intra-arterial C1INH staining and reduced C4d staining in C1INH-treated grafts compared with controls. Posttransplant serum mannose-binding lectin and classical pathway activity and bradykinin levels did not differ between study arms. We conclude that this treatment strategy improves allograft function independent of DGF, likely via local intragraft complement inhibition. Clinical trial registration number: NCT04696146.

Differences between xenotransplantation and allogeneic kidney transplantation: the current situation and future challenges in Japan

Kidney transplantation is the only curative option for patients with chronic renal failure, significantly improving their survival and quality of life. However, this treatment remains limited by the shortage of organ donors. The shortage of kidney donors remains a serious problem all over the world, and is particularly severe in Japan. While advancements in immunosuppressive therapies and histocompatibility testing have improved outcomes in allogeneic kidney transplantation, the rising number of dialysis patients has worsened the gap between the demand for and supply of suitable donor organs. In response to this pressing need, xenotransplantation has gained attention as a promising alternative solution. Recent progress driven by gene-editing technologies, including CRISPR-Cas9, has facilitated the development of genetically modified pigs suitable for potential human transplantation. This review provides an overview of the key differences in immune response and infection risks between xenogeneic and allogeneic kidney transplants. In addition, it comprehensively examines the challenges and potential of xenogeneic kidney transplantation from multiple perspectives, including differences in immunosuppressive therapies between allogeneic and xenogeneic transplantation. We also discuss the feasibility of xenogeneic kidney transplantation as a solution to the organ shortage in Japan and present directions for addressing challenges toward clinical application. We hope this review will provide valuable insights into the potential of xenogeneic kidney transplantation as a new treatment option for chronic renal failure and contribute to efforts to address the donor shortage problem in Japan.

Simultaneous Ex Situ Normothermic Perfusion of Paired Kidneys in Pigs

BACKGROUND

Normothermic Machine Perfusion (NMP) is essential in renal transplantation to improve organ viability before transplantation. This study presents a proof of concept for simultaneous ex situ perfusion of paired porcine kidneys using exogenous creatinine and iohexol clearances to assess renal function, with the primary objective of examining intra-individual differences.

METHODS

Five kidney pairs (n = 10) were harvested from pigs, preserved at 4°C for 3 h, and subjected to 6-h NMP. Each pair was perfused with a solution containing red blood cells, and perfusion parameters were monitored continuously. Biochemical parameters were assessed using hourly perfusate and urine samples. Kidney function was evaluated using creatinine, which was introduced during the priming procedure.

RESULTS

No significant differences were observed between paired kidneys in terms of perfusion and biochemical parameters. Both kidneys maintained stable mean arterial pressures (67.40 ± 12.08 mmHg for right vs. 71.50 ± 4.36 mmHg for left) and flows (68.90 ± 38.61 mL/min vs. 54.00 ± 26.08 mL/min), with consistent electrolyte balance and pH levels. The high inter-individual variability in perfusion and biochemical parameters underscores the importance of paired comparisons.

CONCLUSIONS

This pig model of simultaneous NMP of paired kidneys demonstrates that the intra-individual variance is low, which makes it possible to test treatments prior to kidney transplantation using one kidney as a valid comparator of the other.

Safety of sodium-glucose cotransporter 2 inhibitors in kidney transplant recipients with diabetes mellitus

AIM

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are important anti-hyperglycemic medications with reno-protective benefits for patients with diabetic kidney disease. Their utilization in kidney transplant recipients (KTRs) remains underexplored due to safety concerns, particularly regarding urinary tract infections. This study investigates the safety profile of SGLT2i therapy in KTRs.

METHODS

We conducted a retrospective analysis of KTRs with diabetes mellitus, comparing those treated with SGLT2i to those on standard diabetes therapy, monitored over three years at a tertiary center. The primary outcome was a renal composite of dialysis, re-transplantation, acute kidney failure, or acute rejection. Secondary outcomes included urinary tract infections, diabetic ulcers, fractures, amputations, diabetic ketoacidosis, all-cause mortality, and glycemic control.

RESULTS

Two hundred forty individuals using SGLT2i (median age 63, 20 % female) were matched with non-users. SGLT2i users had a lower incidence of the composite renal outcome (8.9 vs. 13.3 events per 100 patient-years), but after adjustment for independent predictors, the risk was similar (HR 0.99, 95 % CI 0.65-1.52, P = 0.970). Other outcomes showed comparable or lower risks in SGLT2i users. Glycemic control improved more significantly in SGLT2i users.

CONCLUSION

In KTRs with diabetes, SGLT2i therapy improved glycemic control without increased safety concerns compared to standard treatments. Both groups exhibited similar risks of significant kidney-related events and all-cause mortality. These findings provide crucial insights into the existing limited data concerning this vulnerable population, which faces elevated risks of renal complications and medication-related adverse effects. Ongoing randomized controlled trials will provide additional safety data for SGLT2i in KTRs.

Simultaneous Prediction of Area Under the Curves of Mycophenolic Acid and Its Metabolites and Enterohepatic Recirculation in Kidney Transplant Recipients

BACKGROUND

Therapeutic drug monitoring of mycophenolic acid (MPA) is limited due to the requirement for intensive pharmacokinetic sampling to assess the area under the curve (AUC). Limited sampling strategies (LSS) offer a practical alternative; however, enterohepatic recirculation (EHR) affects prediction accuracy and precision. This study is the first to develop LSS models capable of simultaneously predicting the AUC of MPA, its metabolites [mycophenolic acid glucuronide (MPAG) and acyl mycophenolic acid glucuronide (Acyl-MPAG)], and MPA EHR in kidney transplant recipients (KTRs).

METHODS

Intensive pharmacokinetic sampling was conducted in 84 adult KTRs receiving mycophenolate mofetil. MPA AUC0-12 was calculated, and MPA EHR was determined. During the development of the LSS models, a balanced representation of patients with high and low EHR was ensured. Multiple linear regression was used to develop AUC prediction models for MPA, MPAG, and Acyl-MPAG, as well as an EHR prediction model. The best models were selected based on prediction performance, the highest prediction concordance, and the shortest interval between the first and last samples.

RESULTS

Three models for AUC0-12 prediction were identified, incorporating 4, 5, and 6 concentration timepoints. The LSS model with 6 concentrations demonstrated the best performance, with excellent prediction concordance (100% for MPA and MPAG, and 93% for Acyl-MPAG). The EHR prediction model included 4 concentrations and exhibited an ∼80% prediction concordance. An online calculator was developed for these models.

CONCLUSIONS

The developed LSS models simultaneously predict MPA, MPAG, and Acyl-MPAG AUC0-12 using the same timepoints with high accuracy and precision. MPA EHR can be predicted using 4 concentration timepoints. The inclusion of late concentration timepoints is essential for the high predictive performance of LSS models.

CLINICAL TRIAL NOTATION

clinicaltrials.gov, NCT04953715.

Late Allograft Loss and Contemporary Cardiorenal Metabolic Therapies

Late kidney allograft loss occurs through one of two mechanisms: ( 1 ) deterioration of kidney function leading to retransplantation or dialysis (death-censored graft loss) and ( 2 ) premature death with a normally functioning transplant (death with graft function)-each accounting for approximately 50% of late kidney graft losses. Late death-censored graft loss typically results from a combination of immune and nonimmune events leading to common nonspecific end points ( e.g ., tubular atrophy, interstitial fibrosis, and glomerulosclerosis). Conversely, leading causes of death with graft function typically include cardiovascular events, malignancy, and infection. With an improved understanding of the multiple mechanism by which late graft dysfunction develops, there is an opportunity to identify patients at greatest risk and institute novel strategies to quell the process. Newer cardiometabolic agents with proven benefit in the general population have not been well-studied in kidney transplant recipients. However, in addition to their potential benefits in reducing cardiovascular, infectious, and malignancy end points (thus minimizing death with graft function risk), many novel agents may have additional anti-inflammatory and/or antifibrotic benefit (minimizing death-censored graft loss risk) in the kidney transplant population. In this review, we summarize existing literature regarding major causes of death-censored graft loss and death with graft function and discuss the potential roles of new cardiorenal metabolic agents including sodium-glucose cotransport 2 inhibitors, nonsteroidal mineralocorticoid receptor antagonists, glucagon-like peptide 1 receptor agonists, and dual endothelin and angiotensin receptor antagonists in the kidney transplant population, including potential mechanisms to improve death with graft function and death-censored graft loss outcomes.

Patient and Caregiver Perceptions on the Allocation Process and Waitlist, and Accepting a Less-Than-Ideal Kidney: A Canadian Survey

Background

Transplanting less-than-ideal (LTI) kidneys could help optimize organ utilization, but little is known about how patients and caregivers perceive the allocation process, waitlist, or LTI kidneys.

Objective

To explore the perspectives of patients and caregivers on the Canadian kidney transplant allocation process, waitlist, and LTI kidneys.

Design

Electronic survey.

Setting

Canada.

Patients

Transplant recipients, candidates, and caregivers.

Methods

A bilingual electronic national survey was administered from January to March 2024. The questionnaire contained sections on demographics, perceptions of organ allocation and acceptance, LTI kidneys, and educational preferences. Descriptive analysis was performed.

Results

Two hundred fifty-one responses were analyzed, including patients (63%, n = 159), and caregivers (37%, n = 92), from 11 provinces and territories. Three-quarters (74%, n = 186) understood how patients are placed on the waiting list, and 65% (n = 162) understood how donor kidneys are allocated, but 72% (n = 181) and 68% (n = 171) wanted more information about the waitlist and donor kidney allocation criteria, respectively. Approximately 20% felt that the waitlist and allocation processes were not transparent. Awareness about the option to refuse a deceased donor kidney offer was high (69%, n = 174), yet nearly half of respondents (46%, n = 115) expressed concern about being disadvantaged if an offer for a deceased donor kidney was refused. One-third of participants (33%, n = 83) were open to accepting an LTI kidney.

Limitations

Compared to the general population, more study participants were white, and the majority were educated and financially at ease. This limits the generalizability of the results.

Conclusion

Enhanced communication is required to improve transparency and information about the allocation system and waitlist in Canada.

Obesity-associated Inflammation and Alloimmunity

Obesity is a worldwide health problem with a rapidly rising incidence. In organ transplantation, increasing numbers of patients with obesity accumulate on waiting lists and undergo surgery. Obesity is in general conceptualized as a chronic inflammatory disease, potentially impacting alloimmune response and graft function. Here, we summarize our current understanding of cellular and molecular mechanisms that control obesity-associated adipose tissue inflammation and provide insights into mechanisms affecting transplant outcomes, emphasizing on the beneficial effects of weight loss on alloimmune responses.

Association of Socioeconomic Disadvantage and Deceased Donor Kidney Transplant Graft Function

INTRODUCTION

The study of social determinants of health in kidney transplantation has historically focused on equitable access, with limited evidence on the short- and long-term outcomes beyond graft loss and mortality. Our purpose is to identify and assess factors to ensure equitable outcomes after kidney transplant by identifying targets for health-care interventions in the posttransplant phase of care.

METHODS

This is a single institution, cohort study of adults who received deceased donor kidney transplantation at a high-volume transplant center. Transplant recipients were stratified by social deprivation index (SDI) at the population mean of 60. The primary outcome is change in estimated glomerular filtration rate (eGFR).

RESULTS

A total of 236 recipients were included, 48% (n = 113) were from higher deprivation neighborhoods (SDI >60). These recipients were younger, more likely to be black, and had lower estimated posttransplant survival scores. Both groups received grafts with similar kidney donor profile index scores. Despite similar discharge eGFR, recipients from high SDI neighborhoods had significantly lower eGFRs at all follow-up points, confirmed with mixed-effect analysis.

CONCLUSIONS

Recipients from neighborhoods with higher deprivation index have worse short- and long-term graft function, despite being younger, having lower estimated posttransplant survival scores, and similar graft kidney donor profile index at transplantation. This unexplained compromise in graft function is an opportunity for community-based interventions after recipients receive deceased donor kidney transplantation.

Early steroid withdrawal and kidney transplant outcomes in first-transplant and retransplant recipients

BACKGROUND

Early steroid withdrawal (ESW) is often preferred over conventional steroid maintenance (CSM) therapy for kidney transplant recipients with low immunological risks because it may minimize immunosuppression-related adverse events while achieving similar transplant outcomes. However, the risk-benefit balance of ESW could be less favorable in retransplant recipients given their unique immunological risk profile. We hypothesized that the association of ESW with transplant outcomes would differ between first-transplant and retransplant recipients.

METHODS

To assess whether the impact of ESW differs between first and retransplant recipients, we studied 210 086 adult deceased-donor kidney transplant recipients using the Scientific Registry of Transplant Recipients. Recipients who discontinued maintenance steroids before discharge from transplant admission were classified with ESW; all others were classified with CSM. We quantified the association of ESW (vs CSM) with acute rejection, death-censored graft failure and death, addressing retransplant as an effect modifier, using logistic/Cox regression with inverse probability weights to control for confounders.

RESULTS

In our cohort, 26 248 (12%) were retransplant recipients. ESW was used in 30% of first-transplant and 20% of retransplant recipients. Among first-transplant recipients, ESW was associated with no significant difference in acute rejection {adjusted odds ratio (aOR) = 1.04 [95% confidence interval (CI) = 1.00-1.09]}, slightly higher hazard of graft failure [hazard ratio (HR) = 1.09 (95% CI = 1.05-1.12)] and slightly lower mortality [HR = 0.93 (95% CI = 0.91-0.95)] compared with CSM. Nonetheless, among retransplant recipients, ESW was associated with notably higher risk of acute rejection [OR = 1.42 (95% CI = 1.29-1.57); interaction P < .001] and graft failure [HR = 1.24 (95% CI = 1.14-1.34); interaction P = .003], and similar mortality [HR = 1.01 (95% CI = 0.94-1.08); interaction P = .04].

CONCLUSIONS

In retransplant recipients, the negative impacts of ESW on transplant outcomes appear to be non-negligible. A more conservatively tailored approach to ESW might be necessary for retransplant recipients.

Targeting Kidney Inflammation After Brain Death and Cold Storage: Investigating the Potential of an NLRP3 Inflammasome Inhibitor (MCC950) for Preconditioning Donor Kidneys

BACKGROUND

Brain death (BD) and cold storage (CS) are critical factors that induce inflammation in donor kidneys, compromising organ quality. We investigated whether treating kidneys from BD rats with an inflammasome Nod-like receptor family pyrin domain containing 3 (NLRP3) inhibitor (MCC950) followed by CS could reduce kidney inflammation.

METHODS

BD rats were assigned to MCC950-treated or nontreated (NT) groups. Kidneys were evaluated immediately before CS (T0) and after 12 h (T12) and 24 h (T24) of CS. Mean arterial pressure, serum creatinine, gene/protein expression, and histology were evaluated.

RESULTS

At T0, MCC950 treatment did not affect mean arterial pressure but tended to reduce serum creatinine and ameliorated the histological score of acute tubular necrosis. However, MCC950 reduced NLRP3 , caspase-1 , interleukin (IL)-1β , IL-6 , Kim-1 , nuclear factor kappa B , tumor necrosis factor alpha , and caspase-3 gene expression while increasing IL-10 cytokine gene expression. After 12 h of CS, only the expression of the NLRP3 and caspase-1 genes decreased, and after 24 h of CS, no further changes in the gene expression profile were observed. The levels of the inflammasome proteins NLRP3, caspase-1, and IL-1β consistently decreased across all time points (T0, T12, and T24).

CONCLUSIONS

These findings suggest that MCC950 treatment holds promise for mitigating the proinflammatory state observed in kidneys after BD and CS.

GLP-1 and glucagon receptor dual agonism ameliorates kidney allograft fibrosis by improving lipid metabolism

Introduction

Kidney allograft fibrosis accelerates the progression of chronic kidney disease (CKD), leads to allograft failure, and increases patient mortality. Emerging evidence suggests that metabolic syndrome in transplant recipients is associated with fibrosis development. However, it remains unclear whether targeting metabolic pathways can mitigate allograft fibrosis. This study aimed to explore the potential of targeting metabolic pathways using the GLP-1R/GCGR dual agonist TB001 for the treatment of kidney allograft fibrosis.

Methods

Kidney allograft fibrosis was induced in rat kidney transplant models. Histological analysis, transcriptome sequencing, and in vitro experiments were performed to investigate the efficacy of TB001 and its underlying mechanisms.

Results

Compared with the control group, TB001-treated recipients had significantly improved kidney allograft function, as evidenced by lower creatinine and 24-hour urine protein levels. Moreover, TB001 treatment decreased the body weight and serum total cholesterol, LDL-cholesterol, and TNF-α levels in transplant recipients, indicating metabolic improvements. Pathological analysis demonstrated that TB001 treatment reduced inflammatory cell infiltration and downregulated the expression of fibrosis markers, including TGF-β1, α-SMA, COL1A1, and Vimentin. Further transcriptome sequencing of kidney grafts revealed that TB001-treated group had a gene expression pattern similar to that of the syngeneic control group and showed significant enhancement of lipid metabolism-related pathways, particularly the PPAR pathway. In vivo and in vitro experiments further demonstrated that TB001 upregulated the expression of CPT1A, a key molecule involved in lipid metabolism, and inhibited TGF-β1/Smad2/3/Twist and PKC-α/PKC-β pathways.

Conclusion

Targeting metabolic pathways using the GLP-1R/GCGR dual agonist TB001 shows potential for managing kidney allograft fibrosis.

Decreasing efficiency in deceased donor kidney offer notifications under the new distance-based kidney allocation system

Organ Procurement Organizations (OPOs) recover deceased donor kidneys and place them with matched recipients according to ranked match runs of patients, but offer notification practices differ across the OPOs and have changed following updates to allocation policy (kidney allocation system 250 [KAS250]). This national registry study used batch notification data to quantify time spent on kidney allocation and identify variations in batch notification practices across OPOs before and after the KAS250 allocation system era. Overall allocation time between the first and last offer notifications increased from a median of 1 to 7 hours under the KAS250 allocation system. For match runs of unplaced kidneys, allocation time increased from a median of 18 to 28 hours. Out-of-sequence (OOS) allocation, used by OPOs to limit nonutilization due to excess cold ischemia time, more than doubled in frequency between 2018 and 2022, with median time from first offer to initiation of OOS varying across OPOs from 0 to 47 hours. Increasing rates of organ nonutilization and the observed allocation practice differences based on organ quality demonstrate the urgent need for new approaches to achieve more efficient placement of hard-to-place kidneys. Data-driven approaches to optimize kidney allocation efforts will help ensure fairness in a system that currently allows for wide practice variation and frequent OOS allocation.

Robotically procured living donor kidneys transplanted into pediatric recipients

BACKGROUND

Use of living donors for kidney transplantation in pediatric recipients provides optimal long-term graft and patient survival; however, it accounts for only 28.5 % of transplants performed in the United States in 2021. Robotic-assisted living donor nephrectomy is shown to be a safe and feasible option, offering enhanced visualization and improved surgical dexterity, allowing for a potential increase in the living donor pool for pediatric kidney transplant recipients, even in cases of grafts with anatomical variants.

METHODS

We reviewed all pediatric patients (≤18 years of age) that received an open kidney transplant with a robotically procured living donor graft at our institution between October 2022 and July 2023. Recipient and living donor demographics, peri- and post-operative data, and graft characteristics were obtained and analyzed.

RESULTS

Eight pediatric recipients were evaluated. Mean recipient age was 11 years, and seven recipients were male. Four kidney grafts required back-table reconstruction: three underwent vascular reconstruction (two requiring deceased donor vascular grafts as extensions of renal veins; one requiring conjoining of two renal arteries), and one underwent cyst removal. Mean cold and warm ischemia time were 73 and 29 min, respectively. There were no cases of delayed graft function or post-operative vascular or urological complications. Mean serum creatinine value at 1, 3, 6, and 12 months post-transplant was 0.785 mg/dL (N = 8), 0.808 mg/dL (N = 8), 0.818 mg/dL (N = 8) and 0.9 mg/dL (N = 3), respectively.

CONCLUSION

Our study shows that robotically procured living donor kidney grafts, even with anatomical variants, are a safe and feasible source for pediatric kidney transplantation. Utilization of grafts with vascular abnormalities for transplantation after vascular reconstruction does not appear to increase the risk of developing complications and therefore, can increase the donor pool for pediatric transplant candidates.

Using Unsupervised Clustering to Characterize Phenotypes Among Older Kidney Transplant Recipients: A Cohort Study

Background

Older kidney transplant recipients have inferior outcomes compared to younger recipients, and this risk may be compounded by donor characteristics.

Objective

We applied an unsupervised machine learning clustering approach to group older recipients into similar phenotypes. We evaluated the association between each cluster and graft failure, and the impact of donor quality on outcomes.

Design

This is a nationally representative retrospective cohort study.

Setting and Patients

Kidney transplant recipients aged ≥65 years identified from the Scientific Registry of Transplant Recipients (2000-2017).

Measurements and Methods

We used unsupervised clustering to generate phenotypes using 16 recipient factors. Donor quality was evaluated using 2 approaches, including the Kidney Donor Risk Index (KDRI). All-cause graft failure was analyzed using multivariable Cox regression.

Results

Overall, 16 364 patients (mean age 69 years; 38% female) were separated into 3 clusters. Cluster 1 recipients were exclusively female; cluster 2 recipients were exclusively males without diabetes; and cluster 3 recipients were males with a higher burden of comorbidities. Compared to cluster 2, the risk of graft failure was higher for cluster 3 recipients (adjusted hazard ratio [aHR] = 1.25, 95% confidence interval [CI] = 1.19-1.32). Cluster 3 recipients of a lower quality (KDRI ≥1.45) kidney had the highest risk of graft failure (aHR = 1.74, 95% CI = 1.61-1.87) relative to cluster 2 recipients of a higher quality kidney.

Limitations

This study did not include an external validation cohort. The findings should be interpreted as exploratory and should not be used to inform individual risk prediction nor be applied to recipients <65 years of age.

Conclusions

In a national cohort of older kidney transplant recipients, unsupervised clustering generated 3 clinically distinct recipient phenotypes. These phenotypes may aid in complementing allocation decisions, providing prognostic information, and optimizing post-transplant care for older recipients.

Maintenance Immunosuppression in Kidney Transplantation: A Review of the Current Status and Future Directions

Kidney transplantation remains the gold standard for managing end-stage kidney disease, providing superior survival and quality-of-life outcomes compared to dialysis. Despite the ongoing gap between organ availability and demand, it is inevitable that kidney transplantation will continue to grow. This is owed to broader organ sharing, increased comfort of transplant programs with marginal kidney utilization, and the expansion of paired exchange among living donor kidneys. The evolution of kidney transplantation could not have been possible without the availability of effective immunosuppressive regimens that prevent rejection and maintain graft function. Mycophenolic acid and calcineurin inhibitors continue to serve as the foundation of modern maintenance immunosuppression. While these agents have markedly reduced acute rejection rates, their long-term efficacy in graft survival remains suboptimal. Alternative immunosuppressive therapies, including belatacept and mammalian target of rapamycin inhibitors, have demonstrated potential benefits. However, concerns regarding an increased risk of rejection have limited their widespread adoption as primary treatment options. In addition to ongoing efforts to refine steroid- and calcineurin inhibitor-sparing strategies, the identification of practical and quantifiable biomarkers for predicting long-term graft survival remains a critical objective. This review evaluates contemporary immunosuppressive protocols, highlights existing challenges, and explores future directions for optimizing long-term transplant outcomes.

Factors Impacting Early Adverse Outcomes in Simultaneous Heart-Kidney Transplantation

BACKGROUND

Over the last decade, the number of simultaneous heart-kidney transplants (SHKTs) has increased dramatically. There are few reports of renal allograft outcomes in these high acuity patients. The goal of the present study was to identify variables that were related to early adverse outcomes (EAOs), including delayed graft function (DGF), primary non-function (PNF), and renal allograft futility (RAF) after SHKTs.

METHODS

We performed a single center retrospective review of all adults undergoing SHKTs from October 2011 to August 2021. Multivariable logistic regression models with backward elimination were used to test the relationships between recipient (pre-transplant dialysis, intra-aortic balloon pump, serum lactate, norepinephrine use, and re-do sternotomy) and operative (cold ischemia time [CIT]) variables and the likelihood of DGF, PNF, and RAF.

RESULTS

Sixty-eight patients underwent SHKT during the study period. Overall, patient survival was 87%, 83%, and 80% at 6 months, 1 year, and 3 years, respectively. Twenty-four patients (35%) experienced DGF, whereas 4 patients (6%) had PNF, and 12 patients (18%) had RAF (Table 1). Pre-transplant dialysis, serum lactate, and CIT were significantly associated with an increased likelihood of DGF. Norepinephrine (NE) and CIT were associated with increased likelihood of RAF (Table 2).

CONCLUSIONS

Pre-transplant dialysis is related to an increased likelihood of EAO following SHKT, with CIT and NE contributing to increased likelihood of RAF. Given that SHKT recipients are at risk of remaining on dialysis following SHKT, strategies that allow for expedited kidney transplantation after heart transplantation may mitigate the hemodynamic and ischemic constraints of SHKT that contribute to early adverse outcomes.

Influence of Individual- and Area-Level Social Determinants of Health on Likelihood of Living Versus Deceased Donor Kidney Transplantation

Introduction

Social determinants of health (SDOH) are associated with disparities in access to living donor kidney transplantation (LDKT). However, the separate and joint impact of individual- and area-level SDOH on the likelihood of LDKT versus deceased donor kidney transplantation (DDKT) is unclear.

Methods

This retrospective cohort study analyzed adult, kidney-alone recipients transplanted in 2020 or 2022, using data from the organ procurement and transplantation network (OPTN). Individual-level SDOH and patient address were obtained from LexisNexis; area-level SDOH were obtained from the American Community Survey and County Health Rankings. We fit 3 logistic regression models to estimate the effects of the following: (i) individual-level SDOH, (ii) area-level SDOH, and (iii) both individual- and area-level SDOH on the likelihood of LDKT, adjusting for clinical and demographic factors.

Results

This study included 38,964 adult kidney recipients; n = 9664 (25%) received a LDKT. In multilevel, multivariable analysis, adjusting for both individual- and area-level SDOH, higher individual income quartiles were associated with higher odds of LDKT (odds ratio[OR] [95% confidence interval, CI]: 1.35[1.23-1.47]; 1.48[1.35-1.63]; 2.07 [1.87-2.30], for quartiles Q2-Q4, respectively, compared with the Q1 [lowest income]). Although attenuated, the association between neighborhood median household income and likelihood of LDKT persisted after adjusting for individual-level income. The impact of insurance, education level, and county-level SDOH on likelihood of LDKT persisted in models adjusting for both individual- and area-level SDOH.

Conclusion

Our findings suggest that individual- and area-level SDOH play overlapping but distinct roles contributing to disparities in LDKT. Addressing individual- and area-level SDOH is crucial, considering the accentuated effect of income at the individual- rather than area-level.

Outcomes of Kidney Transplantation From Donors on Renal Replacement Therapy

Background

The increasing demand for organs has pushed transplant providers to expand kidney acceptance criteria. The use of kidneys from donors with AKI has been shown to provide good long-term graft survival. We aim to evaluate and compare the outcomes of deceased donor kidney transplantation from donors with acute kidney injury (AKI), either with or without renal replacement therapy (AKI-RRT) before donation.

Methods

A single-center retrospective review of all patients who underwent deceased donor kidney transplantation from AKI donors between 2009 and 2020 was performed. AKI donors were defined on the basis of donor terminal creatinine ≥2.0 mg/dL or use of RRT before donation. We compared the outcomes of recipients receiving a kidney from a donor with AKI versus AKI-RRT. Data are presented as medians (interquartile ranges) and numbers (percentages).

Results

Four hundred ninety-six patients were identified, of whom 300 (60.4%) were men with a median age of 57 y at transplantation. Thirty-nine patients received an AKI-RRT, whereas 457 received an AKI kidney. Donors in the AKI-RRT group were younger (28 versus 40), had less incidence of hypertension (15.3% versus 31.9%), and were more likely to be imported (94.9% versus 76.8%). There was a higher incidence of delayed graft function (72% versus 44%, P < 0.001) in the AKI-RRT group. Recipients in both groups had similar 90-d (100% versus 95.2%) and 1-y (100% versus 91.9%) graft survival. With a median follow-up of 5 y, there was no difference in death-censored graft survival in both groups (P = 0.83).

Conclusions

Careful selection of kidneys from donors with AKI on RRT can be safely used for kidney transplantation with favorable clinical outcomes.

Similar Efficacy in Belatacept-Converted Kidney Transplant Recipients With Steroid-Avoiding Regimen

Introduction

Belatacept offers a valuable alternative to calcineurin inhibitors (CNIs) for reducing toxicity in kidney transplant recipients (KTRs). No study has evaluated the efficacy and safety of late-conversion belatacept with steroid avoidance in KTRs.

Methods

This retrospective multicentric study evaluated the efficacy and safety of a belatacept-based steroid-avoiding therapy, in comparison with concomitant steroid use. The study included KTRs from 4-French transplant centers who were converted to belatacept at least 6 months posttransplantation.

Results

Overall, 512 KTRs were converted to belatacept in a median time of 38 (15.7-83.2) months after kidney transplantation (KT), including 199 patients without steroids after conversion (BelaS-). Median follow-up time was 78.9 (50.3-129.4) months. Compared with the 313 KTRs who had concomitant steroid use (BelaS+), BelaS- patients had a similar acute rejection (AR) rate (19 [6.1%] and 12 [6.0%] patients, P = 0.126, including 13 [68.4%] and 5 [41.7%] T cell-mediated rejection in BelaS+ and BelaS- patients, respectively), and a similar graft survival (graft loss occurred in respectively 23 [7.3%] and 9 [4.5%] patients in BelaS+ and BelaS- groups [P = 0.198]). However, patient mortality was higher among BelaS+ patients (16.6% vs. 3%, P < 0.001). Steroid use was an independent risk factor of mortality (P = 0.009) along with age (P = 0.0001) and diabetes (P = 0.001) at switch and the occurrence of severe infections with belatacept use (P = 0.0005). In addition, BelaS+ patients experienced a higher incidence of severe infections (cumulative incidence of 13.7 vs. 6.7 events/100-person-year), cytomegalovirus (CMV) disease (P < 0.001), infection by norovirus (P < 0.001), and hospitalization with COVID-19 (P < 0.001). BelaS+ patients were significantly more sensitized at conversion (donor-specific antibodies [DSA] in 21.8% vs. 6.6% in BelaS- patients, P < 0.001). DSA incidence remained stable after conversion. BelaS+ patients developed significantly more de novo DSA (14 [4.9%] vs. 2 [1.0%], P < 0.001).

Conclusion

Avoiding steroids in KTRs who are late-converted to belatacept is associated with a similar efficacy along with lower mortality and reduced incidence of severe infections in selected low-sensitized patients.

Novel non-invasive and quantitative assessment of the renal function of transplanted kidneys using Doppler ultrasonography with the vascular index of superb microvascular imaging

PURPOSE

This study assessed the reproducibility and clinical value of the vascular index (VI), derived from superb microvascular imaging (SMI) using Doppler ultrasonography, for evaluating renal function in transplanted kidneys.

METHODS

This retrospective study included 63 renal transplant patients who underwent grayscale and Doppler ultrasonography with SMI from January 2022 to February 2023. The VI of the transplanted kidneys was measured using three methods (VIbox, VIF1, VIF2). The VI was compared across chronic kidney disease (CKD) groups categorized by estimated glomerular filtration rate (eGFR) and Kidney Disease: Improving Global Outcomes (KDIGO) CKD risk groups based on eGFR and albuminuria. The correlation between VI and renal function was evaluated. Univariate and multivariate linear regression analyses were used to identify predictors of eGFR.

RESULTS

Significant differences in VI were observed among CKD groups based on eGFR (VIbox, P=0.001; VIF1, P<0.001; VIF2, P<0.001) and KDIGO CKD groups based on eGFR and albuminuria (VIbox, P=0.039; VIF1, P=0.001; VIF2, P<0.001). VIF1 and VIF2 demonstrated moderate/high correlations with eGFR (r=0.627, P<0.001 and r=0.657, P<0.001, respectively) and serum creatinine (r=-0.626, P<0.001 and r=-0.649, P<0.001, respectively). VIbox moderately correlated with eGFR (r=0.445, P<0.001). Multivariate regression identified the urine albumincreatinine ratio (ACR) (adjusted odds ratio [aOR], 1.122; 95% confidence interval [CI], -0.007 to, 0.000; P=0.030) and VIF2 (aOR, 1.114; 95% CI, 0.466 to 1.235; P<0.001) were independently associated with eGFR.

CONCLUSION

The VI measured by drawing a region of interest along the border of the transplanted kidney in SMI (VIF2) is highly reproducible and correlates well with eGFR. Both VIF2 and ACR independently predict eGFR.

Ex Vivo Surgical Removal Versus Conservative Management of Small Asymptomatic Kidney Stones in Living Donors and Long-term Kidney Transplant Outcomes

BACKGROUND

Donors with small asymptomatic kidney stones have been increasingly accepted because of organ shortages and advances in endoscopic urology. This study aims to evaluate and compare long-term living-donor kidney transplant outcomes following ex vivo surgical removal versus conservative management of donors' gifted asymptomatic stones.

METHODS

Between January 2007 and December 2021, 119 kidney transplant recipients received stone-bearing kidneys, divided into the removal group (N = 63) and observation group (N = 56). We evaluated posttransplant stone events, urinary infections, kidney function, delayed graft function, length of hospital stay, and survival outcomes.

RESULTS

After a median follow-up of 75.5 mo, the removal group had a 10.9% lower absolute incidence of stone events (7/56 [12.5%] versus 1/63 [1.6%]; hazard ratio, 0.08; 95% confidence interval, 0.01-0.77) and a 14.3% lower absolute incidence of urinary infections (16/56 [28.6%] versus 9/63 [14.3%]; hazard ratio, 0.42; 95% confidence interval, 0.19-0.95) than the observation group. The removal group also showed superior kidney graft function. The 2 groups had comparable length of hospital stay (11.0 versus 12.0 d; P  = 0.297) and exhibited similar delayed graft function incidence (1/56 [1.8%] versus 2/63 [3.2%]; P  = 1.000) and urinary stricture incidence (1/56 [1.8%] versus 3/63 [4.8%]; P  = 0.621). Graft survival ( P  = 0.350) and patient survival ( P  = 0.260) were comparable between 2 groups. Subgroup analyses in recipients who received kidneys with stones <4 mm also reported similar results.

CONCLUSIONS

Ex vivo surgical removal might outperform conservative management for donors' gifted asymptomatic kidney stones, improving long-term transplant outcomes and reducing stone events without increasing perioperative complications, even for stones <4 mm.

Use of Normothermic Regional Perfusion in Circulatory Death Donors for Lung Transplantation in the United States

INTRODUCTION

Use of normothermic regional perfusion (NRP) to recover donation after circulatory death (DCD) organs demonstrates increased heart utilization with favorable outcomes. Conversely, DCD lung allograft use when NRP was employed remains controversial. This is a contemporary analysis of DCD lung recipient outcomes in which NRP was used.

METHODS

Utilizing the STAR-OPTN database, all adult DCD lung recipients in the United States between January 1, 2020, and June 30, 2024 were identified. NRP use was defined if the time between donor death and aortic clamp time was greater than 30 min. Recipient outcomes, including 30-, 60-, and 90-day mortality, grade-3 primary graft dysfunction (PGD), and postoperative length of stay were compared using multivariable logistic regression controlling for donor and recipient covariates. Survival analysis was performed using Cox proportional hazard modeling.

RESULTS

Of 987 DCD lung transplants, 92 (9.4%) utilized NRP. There were no differences in recipient characteristics between direct recovery and NRP cohorts. No difference in 30-, 60-, or 90-day mortality, grade-3 PGD, or length of stay was found between cohorts. 12-month survival was equivalent.

CONCLUSIONS

Outcomes between NRP lung recipients were equivalent to DCD direct recovery recipients. Thus, donor lungs may be considered for transplantation following NRP donation procedures.

Pediatric Chronic Kidney Disease During Pandemic Conditions-A Single-Center Experience

Background/Objectives: The prevalence of chronic kidney disease (CKD) is increasing worldwide, and this tendency is also visible in pediatric patients. The major clinical challenge is to achieve a diagnosis as early as possible, despite an overt clinical course, especially in the early stages of the disease. Unfavorable external conditions may disturb the proper treatment of chronically ill patients and delay the time of diagnosis. The recent COVID-19 pandemia might have altered the usual diagnostic pathways of different comorbidities, and CKD was probably one of them. However, there are no data on newly diagnosed CKD in children during the time of the pandemia, so our aim was to approach this problem. Methods: We analyzed medical records of 154 children with CKD who were hospitalized in the Department of Pediatric Nephrology in prepandemic (years 2015-2019) vs. pandemic and postpandemic (2020-2024) conditions, analyzing the eGFR value and stage of CKD at diagnosis, the underlying diseases leading to CKD, and sex-related differences. Results: The number of patients who were diagnosed with CKD in both time periods was comparable. Children hospitalized in the years 2020-2024 presented more often with advanced stages of CKD. The trend towards an increasing share of glomerulopathies, acute kidney injury, and unknown causes of CKD was noticeable under pandemic conditions. Conclusions: The COVID-19 pandemic could, probably owing to reduced access to primary healthcare and disrupted routine check-ups, delay the process of diagnosing CKD in children.

Enzymatic conversion of blood group B kidney prevents hyperacute antibody-mediated injuries in ABO-incompatible transplantation

Matching ABO blood group antigens between donors and recipients is critical to prevent hyperacute rejection in kidney transplantation. Enzymatic conversion of blood group antigens to the universal O type presents a promising strategy to overcome barriers in ABO-incompatible kidney transplantation. In this study, we employ α-galactosidase from Bacteroides fragilis to convert type B kidneys to type O during hypothermic machine perfusion. After 3 hours of perfusion with enzyme, more than 95% of blood group B antigens in the kidney endothelium are effectively removed. Subsequently, enzyme-treated kidneys are protected from antibody-mediated injuries in an ex vivo simulation of ABO-incompatible kidney transplantation. Encouraged by these results, a discarded type B kidney, following enzymatic conversion, is transplanted into a type O brain-dead recipient with high titer of anti-B antibody. The allograft survives for 63 hours without hyperacute rejection. Blood group B antigens re-express within 48 hours, with histopathological analyses indicating no evidence of antibody-mediated rejection. This enzymatic conversion approach holds the potential to broaden the practice of ABO-incompatible kidney transplantation, decrease waiting times and facilitate equitable organ allocation.

GADD45α is a direct target of TFEB and contributes to tacrolimus-induced chronic nephrotoxicity

Tacrolimus-induced chronic nephrotoxicity (TICN) hinders long-term use of tacrolimus, but its mechanism remains unclear. Tacrolimus exerts its pharmacological effect by inhibiting calcineurin and its substrate nuclear factor of activated T cells. Whether the inhibition of other calcineurin substrates is related to TICN remains to be explored. Transcription factor EB (TFEB), a substrate of calcineurin, plays a crucial role in homeostasis. Herein, we found that tacrolimus inhibited TFEB nuclear translocation and activity in mouse kidneys and HK-2 cells. Then, TFEB gain and loss of function rescued and exacerbated, respectively, the effect of tacrolimus in HK-2 cells. Furthermore, TFEB activation by both phosphorylation site mutation and agonist rescued TICN in mice. To elucidate the mechanism of TFEB, we analyzed ChIP-Seq data. We identified growth arrest and DNA damage-inducible 45α (GADD45α) as a transcriptional target of TFEB via ChIP and dual-luciferase reporter assays. Then we revealed that GADD45α overexpression rescued DNA damage and kidney injury caused by tacrolimus or TFEB knockdown in vitro and vice versa. The protective effect of GADD45α against TICN and DNA damage was further demonstrated by overexpressing it in mice. In conclusion, the persistent inhibition of the TFEB/GADD45α pathway by tacrolimus contributes to TICN. This study identifies a specific target for intervention in TICN.

Secular trends in cytomegalovirus (CMV) risk and outcomes: results from a 10-year longitudinal cohort study in adult kidney transplant recipients

BACKGROUND

The goal of this study was to determine the secular trends in the incidence of CMV sero-mismatch (D+/R -) and if these trends meaningfully impact clinical outcomes.

METHODS

This was a single-center longitudinal cohort study in adult kidney recipients transplanted between Jan 2012 and June 2021 with follow-up through June 2022. Baseline and follow-up data were collected. Univariate and multivariate statistics were used to analyze the data.

RESULTS

2,392 kidney transplants were performed during the study period; 132 patients did not meet inclusion criteria. The mean age was 52 years, 41% were female, 57% were black, and 19% were CMV D + /R -. The odds of being CMV high-risk increased by 6% each year (OR 1.06, 1.02-1.10 p = 0.003); 48% of the variability associated with CMV serostatus was explained by transplant year (R2 = 0.478, p = 0.002). Sequential modeling demonstrated that CMV D + /R - serostatus was a substantial risk factor for CMV infection (HR 5.7, 4.5-7.3), CMV disease (HR 8.4, 3.9-18.0), CMV resistance (HR 17.9, 3.8-84.2), CMV refractory infection (HR 35, 4-280), late CMV infection (HR 12.0, 8.3-17.1), acute rejection, and hospitalization for opportunistic infections. Secular trend analysis demonstrated that CMV infections, CMV resistance, and late CMV increased in incidence since 2012. The risks of CMV resistance and late infection was significantly influenced by D + /R - serostatus and transplant year, indicating that this risk is worsening over time.

CONCLUSION

The CMV D + /R - serostatus remains the single most important risk factor for CMV infection, disease, resistance, refractory infection, and late CMV, which appears to be increasing in magnitude.

Limited Sampling Strategies Fail to Accurately Predict Mycophenolic Acid Area Under the Curve in Kidney Transplant Recipients and the Impact of Enterohepatic Recirculation

BACKGROUND

Therapeutic drug monitoring for mycophenolic acid (MPA) is challenging due to difficulties in measuring the area under the curve (AUC). Limited sampling strategies (LSSs) have been developed for MPA therapeutic drug monitoring but come with risk of unacceptable performance. The authors hypothesized that the poor predictive performance of LSSs were due to the variability in MPA enterohepatic recirculation (EHR). This study is the first to evaluate LSSs models performance in the context of EHR.

METHODS

Adult kidney transplant recipients (n = 84) receiving oral mycophenolate mofetil underwent intensive MPA pharmacokinetic sampling. MPA AUC 0-12hr and EHR were determined. Published MPA LSSs in kidney transplant recipients receiving tacrolimus were evaluated for their predictive performance in estimating AUC 0-12hr in our full cohort and separately in individuals with high and low EHR.

RESULTS

None of the evaluated LSS models (n = 12) showed good precision or accuracy in predicting MPA AUC 0-12hr in the full cohort. In the high EHR group, models with late timepoints had better accuracy but low precision, except for 1 model with late timepoints at 6 and 10 hours postdose, which had marginally acceptable precision. For all models, the good guess of predicted AUC 0-12hr (±15% of observed AUC 0-12hr ) was highly variable (range, full cohort = 19%-61.9%; high EHR = 4.5%-65.9%; low EHR = 27.5%-62.5%).

CONCLUSIONS

The predictive performance of the LSS models varied according to EHR status. Timepoints ≥5 hours postdose in LSS models are essential to capture EHR. Models and strategies that incorporate EHR during development are required to accurately ascertain MPA exposure.

Treatment of metastatic melanoma with anti-PD-1 and anti-LAG-3 in a kidney transplant recipient

Immune checkpoint inhibitors (ICI) have quickly emerged as standard therapy in multiple cancers, yet their application in organ transplant recipients (OTRs) remains challenging due to risk of graft rejection. In this case, report, we highlight the successful use of a lymphocyte activation gene 3 (LAG-3) inhibitor, relatlimab, in combination with nivolumab (a programmed cell death protein 1 [PD-1] inhibitor) for the treatment of metastatic melanoma in a kidney transplant recipient. The patient developed a complete metabolic response to therapy. LAG-3 expression was notably positive in the renal graft, but negative in the metastatic melanoma tumor tissue. Although the outcome resulted in rapid renal graft rejection, this underscores the need for further research into LAG-3's dual role in cancer therapy and allograft rejection in organ transplant recipients.

Assessment of the Effect of Brain Death Etiologies on Organs Transplanted Per Donor

OBJECTIVES

We assessed effects of brain death etiology on organ donation, particularly focusing on the number of organs transplanted per donor.

MATERIALS AND METHODS

We evaluated 934 actual donors from 982 brain death cases at our center from April 2016 to July 2023. We analyzed donor cause of death, donor age, sex, blood group, time to consent, and hospital characteristics.

RESULTS

Among 934 actual brain death donors (63.6% male), mean age was 41.44 years. Cause of death was nontraumatic intracranial hemorrhage in 43.3% of cases, followed by trauma, hypoxia, cerebrovascular accident, toxicity, and brain tumor, respectively. Kidney, liver, heart, and lung donations occurred in 696 cases (74.5%), 809 (86.6%), 146 (15.6%), and 25 (3.4%), respectively. Donor cause of death significantly affected kidney donation (P < .001), with highest rates in trauma (83.7%), followed by brain tumors. Although cause of death did not affect liver transplant rates (P = .26), the highest rate was associated with trauma (89.9%), followed by toxicity. Difference in heart transplant rates among different causes of death was significant (P < .001), with highest rates in trauma cases. Similar to liver transplant, lung transplant was similar among different causes of death (P = .3). Organs transplanted per donor averaged 2.52 ± 1.13, with highest numbers associated with trauma (2.88 ± 1.07), followed by drug toxicity, brain tumors, hypoxia, nontraumatic intracranial hemorrhage, and cerebrovascular accident (P < .001). Compared with trauma, differences in organs transplanted per donor were significant for nontraumatic intracranial hemorrhage (mean difference 0.56; 95% CI, 0.39-0.74; P < .001), cerebrovascular accident (mean difference 0.58; 95% CI, 0.29-0.87; P < .001), and hypoxia (mean difference 0.50; 95% CI, 0.26-0.76; P = .002).

CONCLUSIONS

Understanding how cause of death influences donation can help improve organ donation practices and potentially increase the number of organs available for transplant.

Only IF/TA in the Histological Evaluation of Post-Reperfusion Baseline Biopsies Correlates With Kidney Transplant Outcome

Here, we retrospectively evaluated the informational yield of 338 post-reperfusion kidney transplant biopsies (including 95 living donations) assessed according to BANFF for the histological characteristics interstitial fibrosis and tubular atrophy (IF/TA), glomerulosclerosis, arteriosclerosis, and acute tubular injury (ATI). Associations with delayed graft function (DGF) and death-censored graft survival were explored through Cox-regression analyses. The maximum follow-up time was 11.4 years, with DGF observed in 108 (32%) cases. After deceased donation there was no association between DGF and histologic parameters. Univariable Cox-regression unveiled an association of IF/TA and glomerulosclerosis with long-term death-censored graft survival (HR per 10% increase: IF/TA 1.63; 95% CI 1.17-2.28; p = 0.003; glomerulosclerosis 1.19; 95% CI 1.01-1.39; p = 0.031). In multivariable Cox regression analyses, adjusted for recognized clinical risk variables like expanded criteria donor-status, donor age, history of diabetes, and HLA-mismatches, only IF/TA maintained association over the total observation period in deceased donations and in the total cohort. Arteriosclerosis and ATI were not associated with clinical outcome after deceased donation. Especially ATI did not affect delayed graft function if only deceased donations were considered. Our data underlines the role of organ quality for transplant outcome prior to acute lesions such as ATI during the transplantation process.

Age Is Just a Number for Older Kidney Transplant Patients

The rise in the mean age of the global population has led to an increase in older kidney transplant (KT) patients. This demographic shift, coupled with the ongoing organ shortage, requires a nuanced understanding of which older adults are most suitable for KT. Recognizing the increased heterogeneity among older adults and the limitations of solely relying on chronological age, there is a need to explore alternative aging metrics beyond chronological age. In this review, we discuss the impact of older age on access to KT and postoperative outcomes. Emphasizing the need for a comprehensive evaluation that extends beyond chronological age, we explore alternative aging metrics such as frailty, sarcopenia, and cognitive function, underscoring their potential role in enhancing the KT evaluation process. Most importantly, we aim to contribute to the ongoing discourse, fostering an optimized approach to KT for the rapidly growing population of older adults.

Deceased Donor Infectious Diseases Testing and Antimicrobial Use: Surveys of Organ Procurement Organizations and Transplant Professionals

BACKGROUND

Donor screening and antimicrobial management processes are inconsistent across organ procurement organizations (OPOs) and transplant centers. As part of a Controversies Conference addressing the evaluation and management of infectious diseases (ID) in deceased donors sponsored by the American Society of Transplantation (AST), two online pre-meeting surveys were developed to inform conference proceedings and assess current practices and opinions on donor screening and antimicrobial management.

METHODS

Survey 1 addressed the current state of deceased donor ID testing, culture data communication, antimicrobial utilization, and involvement of transplant ID during donor management and was distributed to all 56 United States OPOs. Survey 2 evaluated transplant professionals' opinions regarding donor antimicrobial use and was sent to the AST Infectious Disease, Kidney Pancreas, Liver and Intestinal, and Thoracic and Critical Care Community of Practice listservs. Descriptive statistics were performed.

RESULTS

Thirty-five (63%) unique responses were received from OPOs for Survey 1. Findings included variability in the timing of donor culture collection, frequent sampling of indwelling catheters, wide variation in the location of culture processing, and availability of additional susceptibility testing. Eighty-eight unique responses were received from approximately 1552 (6%) transplant providers for Survey 2. Of the respondents, 37% would not recommend standard antibiotics prior to organ recovery in the absence of suspected or confirmed infection.

CONCLUSIONS

These surveys demonstrate variability in donor testing, donor antimicrobial utilization, and transplant provider opinions regarding the need for and selection of antimicrobial agents. Findings highlight opportunities for standardized approaches to donor testing and management.

Right and left living donor nephrectomy and operative approach: A systematic review and meta-analysis of donor and recipient outcomes

INTRODUCTION

The left kidney is preferable in living donor nephrectomy (LDN). We aimed to investigate the safety and efficacy of right versus left LDN in both donor and recipients. A subgroup analysis of outcomes based on operative approach was also performed.

METHODS

A systematic review and meta-analysis was performed as per PRISMA guidelines. Outcomes of interest were extracted from included studies and analysed.

RESULTS

There were 31 studies included with 79,912 transplants. Left LDN was performed in 84.1 % of cases and right LDN in 15.9 %. Right LDN was associated with reduced EBL (P = 0.010), intra-operative complications (P = 0.030) and operative time (P = 0.006), but higher rates of conversion to open surgery (1.4 % vs 0.9 %). However, right living donor renal transplantation (LDRT) had higher rates of delayed graft function (5.4 % vs 4.2 %, P < 0.0001) and graft loss (2.6 % vs 1.1 %, P < 0.0001). Graft survival was reduced in right LDRT at 3 years (92.0 % vs 94.2 %, P = 0.001) but comparable to left LDRT at 1- and 5-years. Otherwise, donor and recipient peri-operative outcomes and serum creatinine levels were comparable in both groups. Hand-assisted LDN was associated with shorter warm ischaemia time (P < 0.0001) but longer length of stay (LOS) than laparoscopic LDN and robotic-assisted LDN (P < 0.0001). RA-LDN was associated with less EBL and shorter LOS (both P < 0.0001) while patients who underwent L-LDN had a lower mean serum creatinine (SCr) level on discharge (P < 0.0001).

CONCLUSION

Right LDRT has higher rates of delayed graft function and graft loss compared to left LDRT. Minimally-invasive surgical approaches potentially offer improved outcomes but further large-scale randomised controlled trials studies are required to confirm this finding.

Tacrolimus-loaded Drug Delivery Systems in Vascularized Composite Allotransplantation: Lessons and Opportunities for Local Immunosuppression

Long-term systemic immunosuppression is needed for vascularized composite allotransplantation (VCA). The high rate of acute rejection episodes in the first posttransplant year, the development of chronic rejection, and the adverse effects that come along with this treatment, currently prevent a wider clinical application of VCA. Opportunistic infections and metabolic disturbances are among the most observed side effects in VCA recipients. To overcome these challenges, local immunosuppression using biomaterial-based drug delivery systems (DDS) have been developed. The aim of these systems is to provide high local concentrations of immunosuppressive drugs while reducing their systemic load. This review provides a summary of recently investigated local DDS with different mechanisms of action such as on-demand, ultrasound-sensitive, or continuous drug delivery. In preclinical models, ranging from rodent to porcine and nonhuman primate models, this approach has been shown to reduce systemic tacrolimus (TAC) load and adverse effects, while prolonging graft survival. Localized immunosuppression using biomaterial-based DDS represents an encouraging approach to enhance graft survival and reduce toxic side effects of immunosuppressive drugs in VCA patients. Preclinical models using TAC-releasing DDS have demonstrated high local immunosuppressive effects with a low systemic burden. However, to reduce acute rejection events in translational animal models or in the clinical reality, the use of additional low-dose systemic TAC treatment may be envisaged. Patients may benefit through efficient graft immunosuppression and survival with negligible systemic adverse effects, resulting in better compliance and quality of life.

Immune suppression sustained allograft acceptance requires PD1 inhibition of CD8+ T cells

Organ transplant recipients require continual immune-suppressive therapies to sustain allograft acceptance. Although medication nonadherence is a major cause of rejection, the mechanisms responsible for graft loss in this clinically relevant context among individuals with preceding graft acceptance remain uncertain. Here, we demonstrate that skin allograft acceptance in mice maintained with clinically relevant immune-suppressive therapies, tacrolimus and mycophenolate, sensitizes hypofunctional PD1hi graft-specific CD8+ T cells. Uninterrupted immune-suppressive therapy is required because drug discontinuation triggers allograft rejection, replicating the requirement for immune-suppressive therapy adherence in transplant recipients. Graft-specific CD8+ T cells in allograft-accepted mice show diminished effector differentiation and cytokine production, with reciprocally increased PD1 expression. Allograft acceptance-induced PD1 expression is essential, as PDL1 blockade reinvigorates graft-specific CD8+ T cell activation with ensuing allograft rejection despite continual immune-suppressive therapy. Thus, PD1 sustained CD8+ T cell inhibition is essential for allograft acceptance maintained by tacrolimus plus mycophenolate. This necessity for PD1 in sustaining allograft acceptance explains the high rates of rejection in transplant recipients with cancer administered immune checkpoint inhibitors targeting PD1/PDL1, highlighting shared immune suppression pathways exploited by tumor cells and current therapies for averting allograft rejection.

Socioeconomic Inequities in Preemptive Kidney Transplantation and Graft Survival: An Innovative Approach to Identifying Disparities in Kidney Transplantation

Background

The limitations of conventional measures of socioeconomic status (SES) limit our ability to elucidate the role of SES as a key element of social determinants of health in kidney transplantation. This study's objective was to use an innovative SES measure, the HOUsing-based SES measure (HOUSES) index, to examine the effects of social determinants of health on access to and outcomes of kidney transplantation.

Methods

Our study included residents of Minnesota (age older than 18 y) who underwent kidney transplantation at a single center between 2010 and 2020. SES was determined using the HOUSES index, categorized into quartiles (Q1 for lower, Q2-Q4 for higher SES). We used mixed-effects multivariable logistic and Cox models to examine the effects of HOUSES on preemptive transplants, pretransplant dialysis duration, and death-censored graft loss, adjusting for covariates.

Results

Among 1975 eligible patients, 29.4% received preemptive transplants, 34.9% underwent pretransplant dialysis for >3 y, and 15.1% experienced death-censored graft loss for a median follow-up of 7.15 (interquartile range, 4.25-11.38) y. Lower SES recipients (Q1) demonstrated decreased preemptive transplant likelihood (adjusted odds ratio [aOR]: 0.74; 95% confidence interval [CI], 0.57-0.97; P = 0.03), longer dialysis duration (>3 y; aOR: 1.43; 95% CI, 1.01-2.03; P = 0.046), and higher death-censored graft loss (adjusted hazard ratio 1.36; 95% CI, 1.02-1.12; P = 0.036) versus higher SES recipients (Q2-Q4).

Conclusions

We observed significant socioeconomic disparities in kidney transplant access, dialysis duration, and graft survival. The HOUSES index may be a promising tool for individual-based targeted interventions as it identifies SES on an individual rather than an area-level basis.

A walk through the development of human leukocyte antigen typing: from serologic techniques to next-generation sequencing

Human leukocyte antigen (HLA) is a group of glycoproteins encoded by the major histocompatibility complex (MHC) that plays a pivotal role in the host's immune defense. Given that the MHC represents the most polymorphic region in the human genome, HLA typing is crucial in organ transplantation. It significantly influences graft rejection, graft-versus-host disease, and the overall patient outcome by mediating the discrimination between self and nonself. HLA typing technology began with serological methods and has evolved rapidly alongside advances in molecular technologies, progressing from DNA-based typing to next- or third-generation sequencing. These advancements have increased the accuracy of HLA typing and reduced ambiguities, leading to marked improvements in transplantation outcomes. Additionally, numerous novel HLA alleles have been identified. In this review, we explore the developmental history and future prospects of HLA typing technology, which promises to further benefit the field of transplantation.

Laparoscopic and robotic hepatectomy in living liver donors. Current state and prospects

Minimally invasive living-donor hepatectomy is a relatively new surgical technique that can improve donor safety and expedite donor rehabilitation. Following an early stage of research where donor safety was not adequately established, the minimally invasive approach nowadays yields better outcomes when carried out by experienced surgeons. Important factors include donor selection criteria, hospital equipment, and surgeon’s learning curve. This review describes the current status of laparoscopic and robotic living-donor hepatectomy, along with the challenges facing the advancement of these surgical techniques.

Post-transplant glomerular diseases: update on pathophysiology, risk factors and management strategies

In recent years, advancements in immunosuppressive medications and post-transplant management have led to a significant decrease in acute rejection rates in renal allografts and consequent improvement in short-term graft survival. In contrast, recent data have shown an increased incidence of post-transplant glomerular diseases, which currently represent a leading cause of allograft loss. Although pathogenesis is not fully understood, growing evidence supports the role of inherited and immunological factors and has identified potential pre- and post-transplant predictors. In this review, we illustrate recent advancements in the pathogenesis of post-transplant glomerular disease and the role of risk factors and immunological triggers. In addition, we discuss potential prevention and management strategies.

Physician-Directed Mycophenolate Mofetil Dose Reduction After Kidney Transplantation: A Multicenter Real Word Experience

BACKGROUND

Mycophenolate mofetil (MMF) dose is commonly reduced after kidney transplantation (KT). This study examined MMF dosing in the first 5 years after KT to determine if a lower MMF dose impacted outcomes.

METHODS

We retrospectively studied 432 recipients who underwent KT between February 2012 and February 2015 in 3 centers. Induction was with IL-2 receptor blocker (23%) or depleting antibody (67%) and maintenance was with calcineurin inhibitor, MMF 1.5 to 2g/day and in 70% prednisone. MMF dose was reduced within the first post-KT year as clinically indicated or for elevated mycophenolic acid (MPA) levels. All 432 patients underwent 1-year protocol biopsy. Donor-specific antibodies (DSAs) were assessed at 1 year.

RESULTS

At 1 year, 219 KT recipients (51%) received standard MMF (> 1 g/day) and 213 (49%) received low MMF (≤ 1 gr/d). Low MMF was for clinical indication (49%) or elevated MPA level (51%). At 1 year, there was no difference in rejection rate, type and degree of rejection, degree of inflammation, or DSA formation between the low and standard MMF groups (P = not significant [NS]). The reason for MMF dose reduction did not impact outcome. By 5 years, 69% of the KT recipients were on ≤ 1 g/d MMF. The 5-year patient and death-censored graft survival were comparable between the low and standard MMF groups.

CONCLUSIONS

Almost 50% of KT recipients were on low dose MMF at 1 year and this percentage increased by 5 years. We did not observe a difference in outcomes between those on standard or low MMF dose regardless of the reason for dose reduction. Physician-directed MMF dose-reduction may be safe but randomized studies are needed to validate this finding.

HLA EPLET Frequencies Are Similar in Six Population Groups and Are Expressed by the Most Common HLA Alleles

The degree of immunological compatibility between donors and recipients greatly impacts allograft survival. In the United States kidney allocation system, HLA antigen-level matching has been shown to cause ethnic disparities and thus, has been de-emphasised. However, priority points are still awarded for antigen-level zero-ABDR matching, zero-DR matching and one-DR matching. Recently, the degree of HLA molecular (eplet) mismatch has emerged as a more accurate measure of immunological risk, and eplet mismatch load has gained attention as a possible biomarker to improve HLA compatibility. However, little is known about the frequency of eplets in population groups, which is a necessary step to ensure that candidates from any ethnical background can have similar chances at a well-matched organ. Eplet frequencies were estimated using HLA alleles in the Common, Intermediate and Well-Documented (CIWD) 3.0.0 catalogue for six population groups: African-American (AFA), Asian-Pacific Islander (API), European/European descent (EURO), Middle East/North Coast of Africa (MENA), Hispanic/Latino (HIS) and Native-American (NAM). We determined that 98.6% (484 out of 491) of HLA eplets are expressed by the common HLA alleles in all population groups. Of the seven eplets that were expressed by less common HLA alleles, six were Class I eplets and one was expressed by HLA-DQB1 alleles and most were expressed by HLA alleles that were more commonly observed in European/European descent populations. Our observations indicate that HLA eplets will not cause any significant disparity if applied to HLA molecular compatibility, regardless of the ethnic origin of both recipients and donors.

Economic evaluation of weight loss and transplantation strategies for kidney transplant candidates with obesity

Novel antiobesity medications, particularly glucagon-like peptide-1 receptor agonists (GLP-1RAs), have expanded weight loss (WL) options for kidney transplantation (KT) candidates with obesity beyond lifestyle modifications and bariatric surgery. However, varying effectiveness, risk profiles, and costs make strategy choices challenging. To aid decision-making, we used a Markov model to examine the cost-effectiveness of different WL strategies over a 10-year horizon. A target WL of 15% of total body weight was used for the base case scenario, and we compared these strategies to a "liberal" KT strategy of transplanting candidates with obesity. Outcomes included costs (2023 US dollars), quality-adjusted life years, and incremental cost-effectiveness ratios. In analysis, a liberal KT strategy was favored over lifestyle modifications and GLP-1RAs. Among WL strategies, bariatric surgery was the most effective and cost the least, whereas lifestyle modification had the highest cumulative costs and was the least effective. Compared to liberal KT, bariatric surgery costs $45 859 per quality-adjusted life year gained. GLP-1RAs were favored over bariatric surgery only when drug costs were below $5000 per year (base cost $12 077). In conclusion, for KT candidates with obesity, a liberal KT strategy and bariatric surgery are preferred over lifestyle modifications alone and GLP-1RAs based on outcomes and cost-effectiveness.