Lymphocyte depletion and risk of acute rejection in renal transplant recipients at increased risk for delayed graft function

Impact of Cumulative 6 mg/kg Antithymocyte Globulin on Early Posttransplant Outcomes in Kidney Transplant Recipients with Delayed Graft Function

Introduction: Delayed graft function in kidney transplant is associated with an increased risk of rejection and graft loss. Use of rabbit antithymocyte globulin induction in delayed graft function has been correlated with less rejection compared to basiliximab, but optimal dosing remains unknown. Program Evaluation Aims: The purpose of this evaluation was to retrospectively assess the short-term effectiveness and tolerability of a clinical protocol that increased the net state of immunosuppression in delayed graft function kidney transplant recipients using cumulative 6 mg/kg rabbit antithymocyte globulin induction. Design: This retrospective cohort included 88 kidney transplant recipients with delayed graft function, transplanted between January 2017 and March 2021, who either received cumulative 4.5 mg/kg pre-protocol or 6 mg/kg post-protocol rabbit antithymocyte globulin. Outcomes evaluated were biopsy-proven acute rejection and incidence of graft loss, infection, and cytopenia at 6 months. Results: A significant reduction of biopsy-proven acute rejection incidence occurred post-protocol implementation (10/33, 30.3% vs 6/55, 10.9%; P = .04). Of those with rejection, significantly less post-protocol patients were classified as acute cellular rejection (9/10, 90.0% vs 2/6, 33.3%; P = .04). No death-censored graft loss was observed in either group. Rates of cytopenia and infection were similar pre- versus post-protocol implementation. Conclusion: Increasing the exposure to rabbit antithymocyte globulin and maintenance immunosuppression in delayed graft function kidney transplant recipients was tolerable and significantly reduced rejection occurrence at 6 months.

The use of lymphocyte-depleting antibodies in specific populations of kidney transplant recipients: A systematic review and meta-analysis

BACKGROUND

Recommendations of the use of antibody induction treatments in kidney transplant recipients (KTR) are based on moderate quality and historical studies. This systematic review aims to reevaluate, based on actual studies, the effects of different antibody preparations when used in specific KTR subgroups.

METHODS

We searched MEDLINE and CENTRAL and selected randomized controlled trials (RCT) and observational studies looking at different antibody preparations used as induction in KTR. Comparisons were categorized into different KTR subgroups: standard, high risk of rejection, high risk of delayed graft function (DGF), living donor, and elderly KTR. Two authors independently assessed the risk of bias.

RESULTS

Thirty-seven RCT and 99 observational studies were finally included. Compared to anti-interleukin-2-receptor antibodies (IL2RA), anti-thymocyte globulin (ATG) reduced the risk of acute rejection at two years in standard KTR (RR 0.74, 95%CI 0.61-0.89) and high risk of rejection KTR (RR 0.55, 95%CI 0.43-0.72), but without decreasing the risk of graft loss. We did not find significant differences comparing ATG vs. alemtuzumab or different ATG dosages in any KTR group.

CONCLUSIONS

Despite many studies carried out on induction treatment in KTR, their heterogeneity and short follow-up preclude definitive conclusions to determine the optimal induction therapy. Compared with IL2RA, ATG reduced rejection in standard-risk, highly sensitized, and living donor graft recipients, but not in high DGF risk or elderly recipients. More studies are needed to demonstrate beneficial effects in other KTR subgroups and overall patient and graft survival.

Past, Current, and Future Perspectives on Transplanting Acute Kidney Injury Kidneys

(1) Background: Acute kidney injury (AKI) kidneys have high non-utilization rates due to concerns regarding unfavorable outcomes. In this paper, we aimed to review the past, present, and future opinions on AKI kidneys. (2) Methods: A PubMed search was conducted for topics relevant to AKI kidney transplantation. (3) Results: Current short- and long-term data on AKI kidneys have demonstrated good outcomes including favorable graft function and survival. The role of procurement biopsies is controversial, but they have been shown to be beneficial in AKI kidneys by allowing clinicians to differentiate between reversible tubular injury and irreversible cortical necrosis. Machine perfusion has also been applied to AKI kidneys and has been shown to reduce delayed graft function (DGF). The incidence of DGF increases with AKI severity and its management can be challenging. Strategies employed to counteract this have included early initiation of dialysis after kidney transplantation, early targeting of adequate immunosuppression levels to minimize rejection risk, and establishment of outpatient dialysis. (4) Conclusions: Despite good outcomes, there continue to be barriers that impact AKI kidney utilization. Successful strategies have included use of procurement biopsies or machine perfusion and expectant management of DGF. With increasing experience, better use of AKI kidneys can result in additional opportunities to expand the donor pool.

Delayed graft function: current status and future directions

PURPOSE OF REVIEW

Delayed graft function is a common early posttransplant event predictive of adverse outcomes including hospital readmission, impaired long-term graft function, and decreased graft and patient survival. The purpose of this review is to summarize recent literature describing delayed graft function in hopes of better understanding and managing this condition.

RECENT FINDINGS

Recent research efforts have been garnered towards risk factor modification, prevention, and earlier detection of delayed graft function. In this review, we aim to summarize current innovative approaches and future directions.

SUMMARY

Delayed graft function portends worse graft and patient outcomes. Continued research to prevent, and detect early perturbations in allograft function, and more optimally manage this disease will hopefully improve graft function, along with graft/patient survival.

Clinical Events and Renal Function in the First Year Predict Long-Term Kidney Transplant Survival

BACKGROUND

Estimated glomerular filtration rate (eGFR) at 1 year post transplantation has been shown to be a strong predictor of long-term graft survival. However, intercurrent events (ICEs) may affect the relationship between eGFR and failure risk.

METHODS

The OPTN and USRDS databases on single-organ kidney transplant recipients from 2012 to 2016 were linked. Competing risk regressions estimated adjusted subhazard ratios (SHRs) of 12-month eGFR on long-term graft failure, considering all-cause mortality as the competing risk, for deceased donor (DD) and living donor (LD) recipients. Additional predictors included recipient, donor, and transplant characteristics. ICEs examined were acute rejection, cardiovascular events, and infections.

RESULTS

Cohorts comprised 25,131 DD recipients and 7471 LD recipients. SHRs for graft failure increased rapidly as 12-month eGFR values decreased from the reference 60 ml/min per 1.73 m². At an eGFR of 20 ml/min per 1.73 m², SHRs were 13-15 for DD recipients and 12-13 for LD recipients; at an eGFR of 30 ml/min per 1.73 m², SHRs were 5.0-5.7 and 5.0-5.5, respectively. Among first-year ICEs, acute rejection was a significant predictor of long-term graft failure in both DD (SHR=1.63, P<0.001) and LD (SHR=1.51, P=0.006) recipients; cardiovascular events were significant in DD (SHR=1.24, P<0.001), whereas non-CMV infections were significant in the LD cohort (SHR=1.32, P=0.03). Adjustment for ICEs did not significantly reduce the association of eGFR with graft failure.

CONCLUSIONS

Twelve-month eGFR is a strong predictor of long-term graft failure after accounting for clinical events occurring from discharge to 1 year. These findings may improve patient management and clinical evaluation of novel interventions.

The Systemic Immune-Inflammation Index Predicts Clinical Outcomes in Kidney Transplant Recipients

BACKGROUND

Outcomes after kidney transplantation (KTx) remain limited by delayed graft function (DGF) and acute rejection. Non-invasive biomarkers may help identify patients at increased risk for these events. We examined the association between the systemic immune-inflammation index (SII), a novel inflammatory biomarker, and outcomes after KTx and evaluated its ability to predict post-transplant prognosis.

PATIENTS AND METHODS

Adult patients who underwent primary KTx at our institution between 2016-2019 were included. SII was calculated from pre-transplant complete blood counts as the ratio of the neutrophil count to the lymphocyte count multiplied by the platelet count. The cutoff between high and low SII was determined by maximizing the area under the curve. Multivariable logistic and Cox regression were used to identify factors associated with DGF and patient, rejection-free, and graft survival respectively.

RESULTS

Overall, 378 KTx recipients were included; 224 (59.3%) had high SII. On unadjusted analysis, high SII was associated with reduced odds of DGF, and improved patient and rejection-free survival. After adjustment, high SII was independently associated with improved patient survival alone. Multivariable models incorporating SII performed well for the prediction of DGF (c-statistic=0.755) and patient survival (c-statistic=0.786), though rejection-free survival was more difficult to predict (c-statistic=0.635).

CONCLUSION

SII demonstrated limited utility as an independent predictor of outcomes after KTx. However, in combination with other clinically relevant parameters, SII is a useful predictor of post-KTx prognosis. Validation of this novel inflammatory biomarker in a multi-institutional study is needed to further elucidate its practical applications in transplantation.

Microsteatosis in Livers From Donation After Circulatory Death Donors Is Associated With Inferior Outcomes Following Liver Transplantation

The acceptable threshold remains unknown for the percentage of macrosteatosis (MaS) and microsteatosis (MiS) to yield optimal outcomes after donation after circulatory death (DCD) liver transplantation (LT). The purpose of this analysis was to determine the impact of donor liver MaS and MiS on DCD LT outcomes. Using the Organ Procurement and Transplantation Network database, we analyzed pretransplant biopsy results from adult, solitary, DCD livers transplanted between January 1, 2006, and December 31, 2017. Kaplan-Meier analysis was used to assess graft and patient survival based on MaS and MiS severity. MiS was divided into the groups MiS ≤10% and >10%. MaS was divided into the groups MaS ≤15% and >15%. Of 7757 recovered DCD livers, 11.4% (n = 885) were biopsied and transplanted. Patients who received DCD livers with MaS >15% had significantly worse patient survival (P < 0.04), and those with MiS >10% demonstrated inferior graft and patient survival (P < 0.02). In multivariate analyses including known risk factors, both MaS >15% and MiS >10% were associated with increased risk of graft failure and patient mortality (P < 0.03). Recipient and donor age >60 years were also associated with increased risk of graft failure and patient death. This analysis demonstrates that MaS >15% and MiS >10% are additional risk factors for graft loss and patient mortality in DCD LT.

Effectiveness of serum beta-2 microglobulin as a tool for evaluating donor kidney status for transplantation

Kidney transplantations using expanded criteria donors (ECD) are being increasingly adopted, but no consensus tools are available to evaluate donor kidney status. Beta-2 microglobulin (B2MG) is a marker of kidney function, and herein, we evaluate the usefulness of assessing B2MG to evaluate donor kidney status. Fifty-seven kidney transplantations were performed from March 2017 to April 2019. Medical records were retrospectively reviewed, and relationships between clinical and laboratory variables and transplant outcomes were investigated. Thirty-eight patients received a standard criteria donor kidney and 19 patients an ECD kidney. Ten patients experienced delayed graft function (DGF), but no patient experienced primary nonfunction. Of the parameters studied, only donor renal replacement therapy (RRT) [odds ratio (OR) 24.162; p = 0.018] and donor serum B2MG (OR 22.685; p = 0.022) significantly predicted DGF. The presence of either of these two risk factors can better reflect the condition of the donor than previous classification. However, on their last follow-up creatinine and estimated glomerular filtration rate values in those with or without these risk factors were not significantly different. For an ECD with a B2MG level of <7.18 and no history of RRT, kidney transplantation can be undertaken without considering the possibility of kidney discard.

Optimizing anti-T-lymphocyte globulin dosing to improve long-term outcome after unrelated hematopoietic cell transplantation for hematologic malignancies

Prophylaxis of graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HCT) remains challenging. Because prospective randomized trials of in-vivo T cell depletion using anti-T-lymphocyte globulin (ATLG) in addition to a calcineurin inhibitor and methotrexate (MTX) led to conflicting outcome results, we evaluated the impact of ATLG on clinical outcome, lymphocyte- and immune reconstitution survival models. In total, 1500 consecutive patients with hematologic malignancies received matched unrelated donor (MUD) HCT with cyclosporin and MTX (N = 723, 48%) or with additional ATLG (N = 777, 52%). In the ATLG cohort, grades III-IV acute (12% vs 23%) and extensive chronic GVHD (18% vs 34%) incidences were significantly reduced (P < .0001). Nonrelapse mortality (27% vs 45%) and relapse (30% vs 22%) differed also significantly. Event-free and overall survival estimates at 10 years were 44% and 51% with ATLG and 33% and 35% without ATLG (P < .002 and <.0001). A dose-dependent ATLG effect on lymphocyte- and neutrophil reconstitution was observed. At ATLG exposure, lymphocyte counts and survival associated through a logarithmically increasing function. In this survival model, the lymphocyte count optimum range at exposure was between 0.4 and 1.45/nL (P = .001). This study supports additional ATLG immune prophylaxis and is the first study to associate optimal lymphocyte counts with survival after MUD-HCT.

Early Steroid Withdrawal in Deceased-Donor Kidney Transplant Recipients with Delayed Graft Function

BACKGROUND

Early steroid withdrawal (ESW) is associated with acceptable outcomes in kidney transplant (KT) recipients. Recipients with delayed graft function (DGF), however, often have a suboptimal allograft milieu, which may alter the risk/benefit equation for ESW. This may contribute to varying practices across transplant centers.

METHODS

Using the Scientific Registry of Transplant Recipients, we studied 110,019 adult deceased-donor KT recipients between 2005 and 2017. We characterized the association of DGF with the use of ESW versus continued steroid maintenance across KT centers, and quantified the association of ESW with acute rejection, graft failure, and mortality using multivariable logistic and Cox regression with DGF-ESW interaction terms.

RESULTS

Overall 29.2% of KT recipients underwent ESW. Recipients with DGF had lower odds of ESW (aOR=_0.600.67_0.75). The strength of this association varied across 261 KT centers, with center-specific aOR of <0.5 at 31 (11.9%) and >1.0 at 22 (8.4%) centers. ESW was associated with benefits and harms among recipients with immediate graft function (IGF), but only with harms among recipients with DGF. ESW was associated with increased acute rejection (aOR=_1.091.16_1.23), slightly increased graft failure (aHR=_1.011.06_1.12), but decreased mortality (aHR=_0.860.89_0.93) among recipients with IGF. Among recipients with DGF, ESW was associated with a similar increase in rejection (aOR=1.12; 95% CI, 1.02 to 1.23), a more pronounced increase in graft failure (aHR=1.16; 95% CI, 1.08 to 1.26), and no improvement in mortality (aHR=1.00; 95% CI, 0.94 to 1.07). DGF-ESW interaction was statistically significant for graft failure (P=0.04) and mortality (P=0.003), but not for rejection (P=0.6).

CONCLUSIONS

KT centers in the United States use ESW inconsistently in recipients with DGF. Our findings suggest ESW may lead to worse KT outcomes in recipients with DGF.

Utility and safety of early allograft biopsy in adult deceased donor kidney transplant recipients

INTRODUCTION

Delayed graft function (DGF) is considered a risk factor for rejection after kidney transplantation (KTx). Clinical guidelines recommend weekly allograft biopsy until DGF resolves. However, who may benefit the most from such an aggressive policy and when histology should be evaluated remain debated.

METHODS

We analyzed 223 biopsies in 145 deceased donor KTx treated with basiliximab or anti-thymocyte globulin (rATG) and calcineurin inhibitor-based maintenance. The aim of the study was to assess the utility and safety of biopsies performed within 28 days of transplant. Relationships between transplant characteristics, indication, timing, and biopsy-related outcomes were evaluated.

RESULTS

Main indication for biopsy was DGF (87.8%) followed by lack of improvement in graft function (9.2%), and worsening graft function (3.1%). Acute tubular necrosis was the leading diagnosis (89.8%) whereas rejection was detected in 8.2% specimens. Rejection was more frequent in patients biopsied due to worsening graft function or lack of improvement in graft function than DGF (66.7% vs. 3.5%; P = 0.0075 and 33.3% vs. 3.5%; P = 0.0104, respectively) and in biopsies performed between day 15 and 28 than from day 0 to 14 (31.2% vs. 3.7%; P = 0.0002). Complication rate was 4.1%. Management was affected by the information gained with histology in 12.2% cases (7% considering DGF).

CONCLUSIONS

In low-immunological risk recipients treated with induction and calcineurin inhibitors maintenance, protocol biopsies obtained within 2 weeks of surgery to rule out rejection during DGF do not necessarily offer a favourable balance between risks and benefits. In these patients, a tailored approach may minimize complications thus optimizing results.

Blessing and a curse of outpatient management of delayed graft function

Delayed graft function (DGF) is a common complication occurring most often after deceased donor kidney transplant with several donor characteristics as well as immunologic factors that lead to its development post-transplant. These patients require dialysis and close kidney function monitoring until sufficient allograft function is achieved. This has resulted in limited options for DGF management, either prolonged hospitalization until graft function improves to the point where dialysis is no longer needed or discharge back to their home dialysis unit with periodic follow up in the transplant clinic. DGF is associated with a higher risk for acute rejection, premature graft failure, and 30-d readmission; therefore, these patients need close monitoring, immunosuppression management, and prompt allograft biopsy if prolonged DGF is observed. This may not occur if these patients are discharged back to their home dialysis unit. To address this issue, the University of Wisconsin-Madison created a clinic in 2011 specialized in outpatient DGF management. This clinic was able to successfully reduce hospital length of stay without an increase in 30-d readmission, graft loss, and patient death.