Tailored Rabbit Antithymocyte Globulin Induction Dosing for Kidney Transplantation

Low dose rabbit antithymocyte globulin is non-inferior to higher dose in low-risk pediatric kidney transplant recipients

BACKGROUND

Currently, there is no consensus among pediatric kidney transplant centers regarding the use and regimen for immunosuppressive induction therapy.

METHODS

In this single center, retrospective cohort study, pediatric kidney transplant recipients transplanted between 1 May 2013 and 1 May 2018 with rabbit antithymocyte globulin (rATG) induction were included. We stratified patients based on immunological risk, with high risk defined as those with repeat transplant, preformed donor specific antibody, current panel-reactive antibodies > 20%, 0 antigen match and/or African-American heritage. Outcome of interest was the incidence of biopsy proven acute rejection by 1 year.

RESULTS

A total of 166 patients met inclusion criteria. Age of patients was 12 years (11 mo-21 y), (median, range), 21.5% received a living donor transplant and 50.6% were female. Low-immunologic-risk patients were divided into 2 groups, those who received the lower cumulative rATG dose of ≤ 3.5 mg/kg (n = 52) versus the higher cumulative dose of > 3.5 mg/kg (n = 47). The median total dose in the lower dose group was 3.1 (IQR 0.3) and 4.4 (IQR 0.8) in the higher dose group, P < 0.001. Rejection rate did not differ significantly between the 2 treatment groups (7/52 vs. 6/47). None in the lower dose group developed BK nephropathy versus 3 in the higher dose group. Graft loss due to BK nephropathy occurred in 1 patient in the higher dose group. Graft loss in the whole cohort at 12 months was a rare event (n = 1) with 99.5% graft survival and 100% patient survival.

CONCLUSIONS

Reduced rATG dosing (≤ 3.5 mg/kg) when compared to higher dosing (> 3.5 mg/kg) is safe and effective in low-risk pediatric kidney transplant recipients without increasing risk of rejection. A higher resolution version of the Graphical abstract is available as Supplementary information.

The Effects of Different Induction Regimes on Serial Lymphocyte Subsets in Kidney Transplant Recipients: A Single Tertiary Center Experience

BACKGROUND

Immunosuppressive therapy is the backbone of kidney transplantation in preventing acute rejection. T-cell depletion after doses of thymoglobulin is dose-dependent, as are their side effects. At the same time, basiliximab and other maintenance immunosuppressive drugs act at different signals on T lymphocytes. Therefore, studying the pattern of lymphocyte subset depletion depending on the induction regime given at transplantation could be an added tool in managing post-transplant recipients.

METHODOLOGY

This prospective observational study recruited kidney transplant recipients from August 2019 through April 2021 at the University of Malaya Medical Centre. Blood tests for lymphocyte subsets were taken at pre-transplant, 1 week, 1 month, 3 months, and 6 months post-transplantation. At transplantation, recipients received either basiliximab, low-dose thymoglobulin (cumulative dose: 1.5 mg/kg), or standard-dose thymoglobulin (cumulative dose: 5 mg/kg).

RESULTS

A total of 39 patients were recruited: 38.5% received basiliximab (15 of 39), 15.4% received low-dose thymoglobulin (6 of 39), and 46.2% received standard-dose thymoglobulin (18 of 39). Absolute lymphocyte counts 1 week post-transplantation were 1.5 ± 0.84 × 10⁹/L for basiliximab, 0.7 ± 0.57 × 10⁹/L for low-dose thymoglobulin, and 0.1 ± 0.08 × 10⁹/L for standard-dose thymoglobulin (P < .001). The CD4+ and CD8+ counts were severely depleted in the standard-dose thymoglobulin group, with a statistically significant differenceup to 6 months post-transplantation. In the low-dose thymoglobulin group, the CD4+ and CD8+ counts were depleted at 1 week post-transplantation and recovered at 1 month post-transplantation. There was no difference in allograft function and incidence of allograft rejection across groups.

CONCLUSIONS

The effects on lymphocyte counts, CD4+ and CD8+, vary depending on the type and dose of induction immunosuppression. This could be a guiding tool in managing immunosuppression post-transplantation depending on the patient's immunologic risk.

Rabbit antithymocyte globulin dose and early subclinical and clinical rejections in kidney transplantation

Antithymocyte globulin (ATG) is a commonly used induction agent in kidney transplant recipients. However, the optimal dosing has not been well defined. Our protocol aims for a 5-6 mg/kg cumulative dose. It is unclear if a dose lower than 5 mg/kg is associated with more rejection. We performed a retrospective cohort study of patients who received a kidney transplant at our center between January 1, 2013 and December 31, 2016. Primary outcome was biopsy proven acute rejection (clinical and subclinical) in the first six months after kidney transplant. CMV viremia in high risk(D+/R-) recipients and BK viremia was compared as a secondary endpoint. Of the 543 patients, the Low Dose (LD) group (n = 56) received <5 mg/kg ATG and Regular Dose (RD) group (n = 487) received ≧5 mg/kg. Patients in RD were more sensitized (higher PRA and CPRA). LD received a dose of 4 ± 1.1 mg/kg ATG whereas RD received 5.6 ± 0.3 mg/kg ATG (p < 0.001). TCMR(Banff 1A or greater) was present in 34% of patients in LD vs. 22% in RD (p = 0.04) (OR 2.1;95%CI 1.12-3.81;p = 0.019). There was no difference in the incidence of CMV or BK viremia. ATG doses lower than 5 mg/kg may be associated with a heightened risk of rejection despite a low degree of sensitization. This article is protected by copyright. All rights reserved.

Thymoglobulin versus Alemtuzumab versus Basiliximab Kidney Transplantation from Donors After Circulatory Death

Introduction

The Campath, Calcineurin inhibitor (CNI) reduction, and Chronic allograft nephropathy (3C), a study comparing alemtuzumab versus basiliximab induction immunosuppression in kidney transplants, has found lower acute rejection rate with alemtuzumab but same graft survival. The aim of the current study is to evaluate the effect of induction immunosuppression (thymoglobulin, alemtuzumab, basiliximab) on the outcome of kidneys of donors after circulatory death (DCD).

Methods

Data of the 274 DCD patients of the 3C obtained from the sponsor were compounded with the 140 DCD patients who received thymoglobulin in a single center with the same entry criteria as the 3C, giving 414 patients on 3 induction regimes.

Results

There were more male donors (P < 0.05) and human leukocyte antigen and DR mismatched patients in the thymoglobulin group (P < 0.001). Death-censored graft survival at 6 months was 98.6% in the thymoglobulin, 95.5% in the alemtuzumab (P = 0.08), and 95.7% in the basiliximab group (P = 0.09) and at 2 years 97.9% versus 94.8% (P = 0.13, hazard ratio [HR] 2.8, 95% CI 0.7–10.9) versus 94.3% (P = 0.06, HR 3.5, 95% CI 0.9–13.6), respectively.

The 2-year overall graft survival was 95% in the thymoglobulin versus 88% in the alemtuzumab (unadjusted P = 0.038, adjusted HR 2.4, 95% CI 0.99–5.9) and 91.4% in the basiliximab group (P = 0.21). The 2-year patient survival was numerically less in the alemtuzumab compared with the thymoglobulin group (91.8% vs. 97.1%, P = 0.052, HR 2.90, 95% CI 0.93–9.2). Acute rejection was 17% in the basiliximab, 4.3% in the thymoglobulin, and 6% in the alemtuzumab group (P < 0.001).

Conclusion

In DCD transplants, thymoglobulin induction may provide advantage over alemtuzumab in patient survival and the same advantage as alemtuzumab over basiliximab in terms of acute rejection. Differing maintenance immunosuppression may contribute to the difference found.

Association between cumulative rATG induction doses and kidney graft outcomes and adverse effects in kidney transplant patients: a systematic review and meta-analysis

BACKGROUND

This systematic review and meta-analysis were performed to explore the association between rabbit thymoglobulin (rATG) doses and transplant-related efficacy and safety outcomes.

METHODS

We searched PubMed and Scopus databases from inception up to June 2020. The primary efficacy and safety endpoints in kidney transplant recipients were evaluated.

RESULTS

Data of 23 cohort studies (3457 patients) and three RCTs (154 patients) were extracted and analyzed. rATG doses of ≤4.5 m/kg was associated with lower rates of biopsy proven acute rejection, cytomegalovirus infection, BK virus infection, and malignancy with a comparable rate of delayed graft function, patients' mortality, and death-censored graft loss compared to rATG total doses of 4.5-6 mg/kg or more than 6 mg/kg. The rATG doses of 3-4.5 mg/kg was associated with better outcomes in dose-response analysis.

EXPERT OPINION

Cumulative rATG induction doses as much as 3-4.5 mg/kg is as effective as higher doses regarding to allograft and patient outcomes while minimizing potential adverse effects in kidney transplant recipients.

Immunosuppression Considerations for Older Kidney Transplant Recipients

PURPOSE OF REVIEW

While kidney transplantation improves the long-term survival of the majority of patients with end-stage kidney disease (ESKD), age-related immune dysfunction and associated comorbidities make older transplant recipients more susceptible to complications related to immunosuppression. In this review, we discuss appropriate management of immunosuppressive agents in older adults to minimize adverse events, avoid acute rejection, and maximize patient and graft survival.

RECENT FINDINGS

Physiological changes associated with senescence can impact drug metabolism and increase the risk of posttransplant infection and malignancy. Clinical trials assessing the safety and efficacy of immunosuppressive agents in older adults are lacking. Recent findings from U.S. transplant registry-based studies suggest that risk-adjusted death-censored graft failure is higher among older patients who received antimetabolite avoidance, mammalian target of rapamycin inhibitor (mTORi)-based, and cyclosporine-based regimens. Observational data suggest that risk-adjusted mortality may be increased in older patients who receive mTORi-based and cyclosporine-based regimens but lower in those managed with T-cell induction and maintenance steroid avoidance/withdrawal.

SUMMARY

Tailored immunosuppression management to improve patient and graft survival in older transplant recipients is an important goal of personalized medicine. Lower intensity immunosuppression, such as steroid-sparing regimens, appear beneficial whereas mTORi- and cyclosporine-based maintenance are associated with greater potential for adverse effects. Prospective clinical trials to assess the safety and efficacy of immunosuppression agents in older recipients are urgently needed.

A call for transplant stewardship: The need for expanded evidence-based evaluation of induction and biologic-based cost-saving strategies in kidney transplantation and beyond

Rising expenditures threaten healthcare sustainability. While transplant programs are typically considered profitable, transplant medications are expensive and frequently targeted for cost savings. This review aims to summarize available literature supporting cost-containment strategies used in solid organ transplant. Despite widespread use of these tactics, we found the available evidence to be fairly low quality. Strategies mainly focus on induction, particularly rabbit antithymocyte globulin (rATG), given its significant cost and the lack of consensus surrounding dosing. While there is higher-quality evidence for high single-dose rATG, and dose-rounding protocols to reduce waste are likely low risk, more aggressive strategies, such as dosing rATG by CD3+ target-attainment or on ideal-body-weight, have less robust support and did not always attain similar efficacy outcomes. Extrapolation of induction dosing strategies to rejection treatment is not supported by any currently available literature. Cost-saving strategies for supportive therapies, such as IVIG and rituximab also have minimal literature support. Deferral of high-cost agents to the outpatient arena is associated with minimal risk and increases reimbursement, although may increase complexity and cost-burden for patients and infusion centers. The available evidence highlights the need for evaluation of unique patient-specific clinical scenarios and optimization of therapies, rather than simple blanket application of cost-saving initiatives in the transplant population.

The influence of the antithymocyte globulin dose on clinical outcomes of patients undergoing kidney retransplantation

Optimizing antithymocyte globulin (rATG) dosage is critical for high immunological risk patients undergoing a repeat kidney transplant. This natural retrospective cohort study compared clinical outcomes of two successive cohorts of consecutive recipients of retransplants receiving 5 x 1 mg/kg (rATG-5, n = 100) or a single 3 mg/kg (rATG-3, n = 110) dose of rATG induction therapy. All patients had negative complement-dependent cytotoxicity crossmatch and no anti-HLA A, B, DR donor-specific antibodies (DSA). The primary endpoint was efficacy failure (first biopsy-proven acute rejection, graft loss, or death) at 12 months. There was no difference in the cumulative incidence of efficacy failure (18.0% vs. 21.8%, HR = 1.22, 95% CI 0.66–2.25), respectively. There were no differences in 3-years freedom from biopsy proven acute rejection, and patient, graft, and death-censored graft survivals. There were no differences in the incidence of surgical complications (25.0% vs. 18.2%; p 0.151), early hospital readmission (27.8% vs. 29.5%; p = 0.877) and CMV infections (49% vs. 40%; p = 0.190). There were also no differences in the incidence (59.6% vs. 58.7%, p = 0.897) and duration of delayed graft function but a stable difference in estimate glomerular filtration rate was observed from month 1 (54.7±28.8 vs. 44.1±25.3 ml/min/1.73 m², p = 0.005) to month 36 (51.1±27.7 vs. 42.5±24.5, p = 0.019). Mean urinary protein concentration (month 36: 0.38±0.81 vs. 0.70±2.40 g/ml, p = 0.008) and mean chronic glomerular Banff score in for cause biopsies (months 4–36: 0.0±0.0 vs. 0.04±0.26, p = 0.044) were higher in the rATG-3 group. This cohort analysis did not detect differences in the incidence of efficacy failure and in safety outcomes at 12 months among recipients of kidney retransplants without A, B, and DR DSA, receiving induction therapy with a single 3 mg/kg rATG dose or the traditional 5 mg/kg rATG.

Induction with ATG in DCD kidney transplantation; efficacy and relation of dose and cell markers on delayed graft function and renal function

AIM

We aimed to analyse the efficacy of the Thymoglobulin dose used for induction in controlled DCD kidneys, and its initial impact on blood cell and CD3 count, as predictors of efficacy.

METHODS

140 DCD patients who received ATG induction, were analysed. Intended dose was 1.25 mg/kg/day over 5 days, rounded to nearest 25 mg and not exceeding 125 mg/dose. Outcomes included the total dose in relation with rejection, DGF, graft survival, eGFR. The cell count response to ATG was assessed as predictors of outcome.

RESULTS

Graft survival, was 96.2%, 92.4%, 85% at 1, 3 and 5 years. Rejection was 7% at 1 year and associated with eGFR at 3 (p = 0.003) and 5 years. ATG dose was not predictive of rejection but was associated with the day5 leucocyte and lymphocyte count (p < 0.001) and negatively with DGF (p = 0.05). In 31 patients day3 CD3 count was available and it was associated with rejection (p = 0.002), less DGF (p = 0.09), and 3 years eGFR (p = 0.01).

CONCLUSION

Thymoglobulin provides excellent results in DCD kidneys that do not significantly differ with small dose variations. In higher doses it reduces DGF. Lymphocytes and CD3 count, may be useful surrogate markers of efficacy and outcome.

Ideal Body Weight-Based Dosing of Rabbit Antithymocyte Globulin for Cost Minimization in Kidney Transplantation

INTRODUCTION

Contemporary dosing strategies for rabbit anti-thymocyte globulin (rATG) in kidney transplantation aim to reduce cumulative exposure, minimizing long-term adverse events. The use of ideal body weight-based dosing has been trialed, however concern for increased rejection post-transplant exists due to lower doses of rATG. Research Questions: The primary aim of this study was to compare rejection rates between rATG dosing protocols using actual body weight and ideal body weight and secondarily to evaluate cost savings following protocol implementation.

DESIGN

This was a retrospective study surrounding implementation of an ideal body weight-based dosing protocol for rATG. We compared 75 kidney transplant recipients in whom rATG was dosed based on actual body weight (pre-protocol group) to 64 in whom dosing was based on ideal body weight (post-protocol group), following a nine-month washout.

RESULTS

The mean cumulative rATG dose in the pre-protocol group was 6.3 mg/kg of actual body weight. When ideal body weight was used in the post-protocol group, the mean dose was 4.5 mg/kg of actual body weight. The rejection rate was 18.7% pre-protocol and 23.4% postprotocol, which did not represent a statistically significant difference (p = 0.491). The actual annual cost savings after protocol implementation exceeded $162,000, approximately $2,500 per patient.

CONCLUSION

Results suggest ideal body weight-based dosing of rATG may reduce exposure and cost, without significantly impacting the risk of rejection in kidney transplant recipients. More studies are needed to confirm these findings.

Decreased incidence of acute rejection without increased incidence of cytomegalovirus (CMV) infection in kidney transplant recipients receiving rabbit anti-thymocyte globulin without CMV prophylaxis - a cohort single-center study

Induction therapy with rabbit anti-thymocyte globulin (rATG) in low-risk kidney transplant recipients (KTR) remains controversial, given the associated increased risk of cytomegalovirus (CMV) infection. This natural experiment compared 12-month clinical outcomes in low-risk KTR without CMV prophylaxis (January/3/13-September/16/15) receiving no induction or a single 3 mg/kg dose of rATG. We used logistic regression to characterize delayed graft function (DGF), negative binomial to characterize length of hospital stay (LOS), and Cox regression to characterize acute rejection (AR), CMV infection, graft loss, death, and hospital readmissions. Recipients receiving 3 mg/kg rATG had an 81% lower risk of AR (aHR 0.14 0.190.25 , P < 0.001) but no increased rate of hospital readmissions because of infections (0.68 0.911.21 , P = 0.5). There was no association between 3 mg/kg rATG and CMV infection/disease (aHR 0.86 1.101.40 , P = 0.5), even when the analysis was stratified according to recipient CMV serostatus positive (aHR 0.94 1.251.65 , P = 0.1) and negative (aHR 0.28 0.571.16 , P = 0.1). There was no association between 3 mg/kg rATG and mortality (aHR 0.51 1.253.08 , P = 0.6), and graft loss (aHR 0.34 0.731.55 , P = 0.4). Among low-risk KTR receiving no CMV pharmacological prophylaxis, 3 mg/kg rATG induction was associated with a significant reduction in the incidence of AR without an increased risk of CMV infection, regardless of recipient pretransplant CMV serostatus.

Low-Dose Antithymocyte Globulin Has No Disadvantages to Standard Higher Dose in Pediatric Kidney Transplant Recipients: Report From the Pediatric Nephrology Research Consortium

Introduction

Rabbit antithymocyte globulin (rATG) dosing strategies for induction in pediatric kidney transplantation vary between centers. It is not known whether a lower rATG induction dose provides safe and effective immunosuppression compared with a “standard” higher dose.

Methods

We performed a retrospective multicenter study of all isolated first-time kidney transplant recipients <21 years old who received rATG induction between 1 January 2010 and 31 December 2014 at 9 pediatric centers. An a priori cutoff of a 4.5-mg/kg cumulative rATG dose was used to identify low (≤ 4.5 mg/kg) and standard (> 4.5 mg/kg) exposure groups. Outcomes examined included 12 months posttransplant graft function (estimated glomerular filtration rate [eGFR]); the occurrence of acute rejection, donor-specific antibody (DSA), neutropenia, and viral infection (cytomegalovirus [CMV], Epstein-Barr virus [EBV], and BK virus); and 24-month outcomes of posttransplant lymphoproliferative disorder (PTLD) occurrence and patient and graft survival.

Results

Two hundred thirty-five patients were included. Baseline features of the low and standard rATG dose groups were similar. By 12 months, the rATG dose group had no significant impact on the occurrence of neutropenia, positive DSA, or viral polymerase chain reaction (PCR). Graft function was similar. Acute rejection rates were similar at 17% (low dose) versus 19% (standard dose) (P = 0.13). By 24 months, graft survival (96.4% vs. 94.6%) and patient survival (100% vs. 99.3%) were similar between the low- and standard-dose groups (P = 0.54 and 0.46), whereas the occurrence of PTLD trended higher in the standard-dose group (0% vs. 2.6%, P = 0.07).

Conclusion

A low rATG induction dose ≤ 4.5 mg/kg provided safe and effective outcomes in this multicenter low immunologic risk pediatric cohort. Prospective studies are warranted to define the optimal rATG induction dose in pediatric kidney transplantation.

Antithymocyte induction dosing and incidence of opportunistic viral infections using steroid-free maintenance immunosuppression

BACKGROUND

Currently, there is limited literature evaluating rATG induction dosing and incidence of opportunistic viral infections when using steroid-free maintenance immunosuppression.

METHODS

This single-center, retrospective, study compared high rATG (>4.5 mg/kg) versus low (<4.5 mg/kg) induction dosing and the overall incidence of early opportunistic viral infection at 180 days in the setting of maintenance immunosuppression consisting of tacrolimus, mycophenolate, rapid steroid withdrawal, and a tiered antiviral prevention strategy based on donor-recipient Cytomegalovirus (CMV) serostatus.

RESULTS

A total of 209 patients were included; 76 patients received low-dose and 133 patients received high-dose rATG. Incidence of overall opportunistic viral infection occurred more frequently in patients who received high compared to low dose (29.8% vs 25% p = .030). Incidence of CMV infection was also significantly increased in the high-dose group (31.6% vs 18.4% p = .039). In a multivariable model, rATG dose, as a continuous variable, remained a significant independent predictor of infection along with CMV risk (OR 1.46, 95% CI 1.02-2.09) controlling for age and CMV risk. There were no differences in graft-related outcomes at 180 days.

CONCLUSION

Higher cumulative rATG induction dose was associated with increased incidence of opportunistic viral infections, in the setting of a steroid-free maintenance immunosuppression in the early post-transplant period.

Reassessing Rabbit Antithymocyte Globulin Induction in Kidney Transplantation (RETHINK): An Analysis of the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) Registry

Supplemental Digital Content is available in the text.

Background.

There is no consensus on rabbit antithymocyte globulin (rATG) dose used for induction immunosuppression in pediatric kidney transplants. We aimed to identify whether a lower rATG dose provides safe and effective immunosuppression compared with a higher dose.

Methods.

We retrospectively analyzed all first-time kidney transplant recipients (aged <21 y) in the North American Pediatric Renal Trials and Collaborative Studies registry since 1998 on mycophenolate mofetil– and tacrolimus-based immunosuppression with rATG induction. An a priori cutoff of 7.5 mg/kg cumulative rATG dose was used to identify low (<7.5 mg/kg) and high (≥7.5 mg/kg) exposure groups. Primary outcome was time to first-acute rejection episode. Secondary outcomes included graft function, patient survival, hospitalizations due to infections, and time to first-posttransplant lymphoproliferative disorder episode.

Results.

Four hundred fifty-five patients met inclusion criteria (59% male, 49% whites, 26% blacks, 38% living donor source). Median cumulative rATG dose was 6.8 mg/kg with a median of 5 doses and a median 1.5 mg/kg/dose introduced at a median of postoperative 0 days. Sixty-four percent received <7.5 mg/kg total rATG. There was no difference in age at transplant, gender, race, end-stage renal disease causes, or HLA mismatch among groups. Time to first-acute rejection was similar (P = 0.07). There was no significant difference in graft or patient survival or time to posttransplant lymphoproliferative disorder. Hospitalization for infection rates was similar.

Conclusions.

These data demonstrate a wide variation in cumulative rATG induction dose. A smaller rATG dose <7.5 mg/kg may provide effective and safe immunosuppression compared with a higher dose.