The use of induction therapy in liver transplantation is highly variable and is associated with posttransplant outcomes

Immunosuppression regimen and latitude impact keratinocyte carcinoma risk in U.S. liver transplant recipients

Immunosuppression after solid organ transplantation is associated with an increased risk of keratinocyte carcinoma (KC). Despite its established morbidity, KC risk in liver transplant (LT) recipients is understudied, including the contribution of immunosuppression regimen and latitude. A retrospective cohort of 9,966 adult first LT alone recipients alive with their native allograft at 1-year post-LT without prior KC between 2007 and 2016 were identified using linked data from the Organ Procurement and Transplantation Network and Medicare administrative claims. The primary exposures were immunosuppression regimen and latitude of residence. The primary outcome was incident, de novo KC occurring at least 1-year after LT. Adjusted Cox regression analysis stratified by transplant center was used in all analyses. The cohort was 63.4% male, 70.2% White and with median age 61 years (interquartile range, IQR, 54-66) at transplant. Calcineurin inhibitor (CNI) with anti-metabolite combination was independently associated with incident KC when measured as intention-to-treat (adjusted hazard ratio (aHR) 1.21 vs. CNI monotherapy, 95% CI 1.02-1.43, p = 0.026), in a time-updating as-treated analysis (aHR 1.61, 95% CI 1.34-1.93; p < 0.001) and when measured as cumulative exposure (aHR 1.13 per 6-month increase, 95% CI: 1.02-1.33; p = 0.027). More southern latitude of residence was also independently associated with incident KC with an aHR of 1.26 per 5°N decrease towards the Equator (95% CI: 1.08-1.47, p = 0.003). We demonstrate independent effects of CNI with antiM immunosuppression regimen and latitude of residence on the risk of post-LT KC, which will better inform screening practices and immunosuppression management.

Basiliximab Induction and Postoperative Steroid-free Immunosuppression With Tacrolimus in Pediatric Liver Transplantation: A Randomized Clinical Trial

BACKGROUND

Optimizing the immunosuppressive regimen is essential to improve the long-term outcomes of pediatric liver transplant recipients.

METHODS

We conducted a prospective, randomized, open-label study to compare the safety and efficacy of 2 treatment approaches during pediatric liver transplantation: tacrolimus monotherapy following basiliximab induction (the study group) and a dual regimen of tacrolimus plus steroids (the control group). A total of 150 patients were enrolled, with 75 patients allocated to each group.

RESULTS

In both groups, recipients achieved graft and recipient overall survival rates exceeding 93%, with no statistically significant differences between them. However, the study group exhibited a significantly lower incidence of acute cellular rejection (ACR), delayed occurrence of ACR, and an improved ACR-free survival rate at 2 y compared with the control group. Notably, the study group also showed a significant reduction in the incidence of de novo donor-specific antibodies at 3-mo and 2-y posttransplant. Furthermore, 6 mo after the transplant, the study group demonstrated significant improvements in weight-for-age Z score and height-for-age Z score. No notable differences were observed in postoperative complications or the incidence of liver fibrosis between the 2 groups.

CONCLUSIONS

Basiliximab induction combine with tacrolimus (TAC) monotherapy is a safe and effective immunosuppressive regimen to reduce the episodes of ACR without influencing the development of liver fibrosis and graft and recipient survival rate after pediatric liver transplantation.

Hospitalizations for opportunistic infections following transplantation and associated risk factors: A national cohort study of Medicare beneficiaries

BACKGROUND

Opportunistic infections (OIs) are a significant cause of morbidity and mortality after organ transplantation, though data in the liver transplant (LT) population are limited.

METHODS

We performed a retrospective cohort study of LT recipients between January 1, 2007 and Deceber 31, 2016 using Medicare claims data linked to the Organ Procurement and Transplantation Network database. Multivariable Cox regression models evaluated factors independently associated with hospitalizations for early (≤1 year post transplant) and late (>1 year) OIs, with a particular focus on immunosuppression.

RESULTS

There were 11 320 LT recipients included in the study, of which 13.2% had at least one OI hospitalization during follow-up. Of the 2638 OI hospitalizations, 61.9% were early post-LT. Cytomegalovirus was the most common OI (45.4% overall), although relative frequency decreased after the first year (25.3%). Neither induction or maintenance immunosuppression were associated with early OI hospitalization (all p > .05). The highest risk of early OI was seen with primary sclerosing cholangitis (aHR 1.74; p = .003 overall). Steroid-based and mechanistic target of rapamycin inhibitor-based immunosuppression at 1 year post LT were independently associated with increased late OI (p < .001 overall).

CONCLUSION

This study found OI hospitalizations to be relatively common among LT recipients and frequently occur later than previously reported. Immunosuppression regimen may be an important modifiable risk factor for late OIs.

Simultaneous combined transplantation: Intricacies in immunosuppression management

Simultaneous combined transplantation (SCT), i.e. the transplantation of two solid organs within the same procedure, can be required when the patients develop more than one end-stage organ failure. The development of SCT over the last 20 years could only be possible thanks to progress in the surgical techniques and in the perioperative management of patients in an ageing population. Performing such major transplant surgeries from the same donor, in a short amount of time, and in critical pathophysiological conditions, is often considered to be counterbalanced by the immune benefits expected from these interventions. However, SCT includes a wide array of different transplant combinations, with each time a different immunological constellation. Recent research offers new insights into the immune mechanisms involved in these different settings. Progress in the understanding of these immunological intricacies help to address the optimal induction and maintenance immunosuppressive treatment strategies. In this review, we summarize the different immunological benefits according to the type of SCT performed. We also incorporate the main outcomes according to the immunological risk at transplantation, and the deleterious impact of preformed or de novo donor-specific antibodies (DSA) in the different types of SCT. Finally, we propose comprehensive and evidence-based induction and maintenance immunosuppression strategies guided by the type of SCT.

Immunosuppressive Induction Therapy Using the Antithymocyteglobulin Grafalon: A Single-Center Non-Interventional Study

Background: Induction therapy with depleting antibodies in the setting of liver transplantation (LT) is discussed controversially to this day. The rabbit antithymocyteglobulin (ATG) Thymoglobulin (rATG) was introduced as early as 1984 and was frequently used as a standard regime for induction therapy after LT. There are no public reports characterizing Grafalon (ATG-F), a novel ATG, as an induction agent after LT. Objectives: The aim of this observational non-interventional study was to investigate the safety and efficacy of Grafalon induction therapy and characterize its clinical effects in the setting of LT. Methods: A cohort of 80 patients undergoing deceased donor LT at the Medical University of Vienna and receiving Grafalon as part of the clinical standard immunosuppressive regimen was prospectively included between March 2021 and November 2022. Patients were monitored closely for leukocytopenia and thrombocytopenia during the first postoperative week and followed up for incidence and severity of biopsy-proven acute rejection (BPAR), overall survival, and bacterial infections in the first year after LT. Results: The incidences of thrombocytopenia and leukocytopenia following Grafalon treatment peaked on postoperative day four, with 64% and 31%, respectively. However, there were no cases of severe leukocytopenia after the first postoperative week. Induction therapy with Grafalon resulted in a rate of localized bacterial infections and bacteremia of 28% and 21%, respectively. The rate of BPAR was 12.5% in the first year after LT; the one-year survival rate in this cohort was 90%. Conclusions: Overall, this study provides evidence of the safety and efficacy of Grafalon as an induction agent. Further studies investigating the potential long-term effects of Grafalon, as well as comparison studies with different immunosuppressive regimens, are needed in order to draw further conclusions.

Detrimental impact of immunosuppressive burden on clinical course in patients with Cytomegalovirus infection after liver transplantation

INTRODUCTION

Cytomegalovirus (CMV)-infection and reactivation remain a relevant complication after liver transplantation (LT). The recipient and donor serum CMV-IgG-status has been established for risk stratification when choosing various pharmaceutical regimens for CMV-prophylaxis in the last two decades. However, factors influencing course of CMV-infection in LT remain largely unknown. In this study, the impact of immunosuppressive regimen was examined in a large cohort of patients.

METHODS

All patients that underwent primary LT between 2006 and 2018 at the Charité-Universitaetsmedizin, Berlin, were included. Clinical course as well as histological and laboratory findings of patients were analyzed our prospectively maintained database. Univariate and multivariate regression analysis for impact of variables on CMV-occurrence was conducted, and survival was examined using Kaplan-Meier analysis.

RESULTS

Overall, 867 patients were included in the final analysis. CMV-infection was diagnosed in 325 (37.5%) patients after transplantation. Significantly improved overall survival was observed in these patients (Log rank = 0.03). As shown by correlation and regression tree classification and regression tree analysis, the recipient/donor CMV-IgG-status with either positivity had the largest influence on CMV-occurrence. Analysis of immunosuppressive burden did not reveal statistical impact on CMV-infection, but statistically significant inverse correlation of cumulative tacrolimus trough levels and survival was found (Log rank < .001). Multivariate analysis confirmed these findings (p = .02).

DISCUSSION

CMV-infection remains of clinical importance after LT. Undergone CMV-infection of either recipient or donor requires prophylactic treatment. Additionally, we found a highly significant, dosage-dependent impact of immunosuppression (IS) on long-term outcomes for these patients, underlying the importance of minimization of IS in liver transplant recipients.

Immunotherapy and Liver Transplantation: The Future or the Failure?

A quarter century has passed since the milestone study by Mazzaferro and colleagues on liver transplantation (LT) for hepatocellular carcinoma (HCC). The increasing demand for LT for HCC has led to the continued efforts to expand LT indications. Downstaging to within Milan criteria has been incorporated into the organ allocation policy for HCC in the United States in 2017 and provides acceptable long-term survival. The present review focuses on the rationale of neoadjuvant immune checkpoint inhibitor (ICI) in HCC, the experience of ICI in the pre- and posttransplant setting.

Current Use of Immunosuppression in Liver Transplantation

Since the first successful liver transplant in 1967, immunosuppression has allowed liver transplantation to become the standard treatment of end-stage liver disease. Over the decades, the rates of rejection have decreased, and patient survival outcomes have significantly improved in large part due to the introduction and advancements of immunosuppression medications. However, the adverse effects associated with long-term immunosuppression have created new challenges facing liver transplantation and added significantly to posttransplantation morbidity. This review presents the data and rationale for immunosuppression approaches, addresses the main controversies related to immunosuppression in liver transplantation, and explores some of the newer advancements in immunosuppressive drug therapy.

Chronic Kidney Disease After Liver Transplantation

Chronic kidney disease among liver transplant recipients is common and associated with an increased mortality risk. Several risk factors and causes for the development of chronic kidney disease have been identified. They can be divided into perioperative factors, such as unresolved acute kidney injury; donor-related factors, such as the use of extended criteria liver allografts; and recipient-related factors, such as the use of calcineurin inhibitors and the presence of metabolic syndrome, diabetes, and obesity. There is a bimodal progression, more prominent during the initial post-transplant months, followed by a gradual but progressive decline over the subsequent years. Management strategies to prevent and treat chronic kidney disease in the general population can be reasonably applied to the liver transplant population and include addressing comorbidities such as hypertension and diabetes. Strategies to minimize or withdraw calcineurin inhibitors from the immunosuppressive regimen can slow progression of kidney dysfunction. Patients with advanced chronic kidney disease should be considered for kidney transplantation due to its survival advantage. Allocation policy in the United States confers safety-net allocation priority for liver transplant recipients who develop advanced chronic kidney disease within the first year of liver transplantation.

Induction Immunosuppression Does Not Worsen Tumor Recurrence After Liver Transplantation for Hepatocellular Carcinoma

BACKGROUND

Prior studies are inconsistent regarding the impact of antibody induction therapy on outcomes after liver transplantation (LT) for hepatocellular carcinoma (HCC).

METHODS

Adults transplanted with HCC exception priority were identified from February 27, 2002, to March 31, 2019, using the United Network for Organ Sharing database. Time-to-event analyses evaluated the association of antibody induction therapy (none, nondepleting induction [NDI], depleting induction [DI]) with overall post-LT patient survival and HCC recurrence. Separate multivariable models adjusted for tumor characteristics on either last exception or on explant. The interaction of induction and maintenance regimen at LT discharge was investigated.

RESULTS

Among 22 535 LTs for HCC, 17 688 (78.48%) received no antibody induction, 2984 (13.24%) NDI, and 1863 (8.27%) DI. Minimal differences in patient and tumor characteristics were noted between induction groups, and there was significant center variability in practices. NDI was associated with improved survival, particularly when combined with a calcineurin inhibitor (CNI) and antimetabolite (hazard ratio [HR] 0.73 versus no induction plus 3-drug therapy in the last exception model [ P  < 0.001]; HR 0.64 in the explant model [ P  = 0.011]). The combination of DI with CNI alone was also protective (HR 0.43; P  = 0.003). Neither NDI nor DI was associated with tumor recurrence (all P  > 0.1). However, increased HCC recurrence was observed with no induction plus CNI monotherapy (HR 1.47, P  = 0.019; versus no induction plus 3-drug therapy).

CONCLUSIONS

In conclusion, induction immunosuppression was not associated with worse post-LT outcomes in patients transplanted with HCC exception priority. An improvement in survival was possibly observed with NDI.

The effectiveness and safety of antibody induction immunosuppression in a large cohort of United States pediatric liver transplant recipients

Data on the potential benefits and risks of induction therapy in pediatric liver transplantation (LT) are limited. This was a retrospective cohort study of 2748 pediatric LT recipients at 26 children's hospitals between January 1, 2006 to May 31, 2017 using data from the pediatric health information system linked to the United Network for Organ Sharing database. The induction regimen was obtained from the pediatric health information system day-by-day pharmacy resource utilization. Cox proportional hazards evaluated the association of induction regimen (none/corticosteroid-only, nondepleting, and depleting) on patient and graft survival. Additional outcomes, including opportunistic infections and posttransplant lymphoproliferative disorder, were studied using multivariable logistic regression. Overall, 64.9% received none/corticosteroid-only induction, whereas 28.1% received nondepleting, 8.3% received depleting, and 2.5% other antibody regimens. Differences in patient characteristics were small, but center practices were heterogeneous. Compared with none/corticosteroid-only induction, nondepleting induction was associated with reduced acute rejection (odd ratio [OR], 0.53; P <.001) but with the increased posttransplant lymphoproliferative disorder (OR, 1.75; P =.021). Depleting induction was associated with improved graft survival (hazard ratio [HR], 0.64; P =.028) but with increased noncytomegalovirus opportunistic infections (OR, 1.46; P =.046). Depleting induction is underused yet may offer long-term benefits in this large multicenter cohort. Greater consensus guidance in this aspect of pediatric LT care is warranted.

Recipient and Center Factors Associated With Immunosuppression Practice Beyond the First Year After Liver Transplantation and Impact on Outcomes

BACKGROUND

Immunosuppression is a critical aspect of post-transplant management, yet practices at intermediate and late time points after liver transplantation (LT) are poorly characterized.

METHODS

A retrospective cohort of 11 326 adult first LT alone recipients between 2007 and 2016 was identified by linking United Network for Organ Sharing transplant data to Medicare administrative claims. The immunosuppression regimen was obtained from Medicare billing claims. Factors associated with calcineurin inhibitor (CNI) monotherapy at 1-, 3-, and 5-y post-LT were investigated using mixed-effects logistic regression. Center practice heterogeneity was evaluated. The association of immunosuppression regimen (time-updating) with patient and graft survival was studied.

RESULTS

CNI monotherapy was used in 51.9% at 1-y post-LT and 68.6% at 5-y post-LT. Center-specific rates ranged from 20.0%-79.9% to 15.4%-95.2%, respectively. CNI monotherapy at 1- and 3-y post-LT was less likely among Black recipients ( P = 0.027 and P = 0.015 versus White, respectively). CNI plus antimetabolite was associated with improved adjusted patient (hazard ratio, 0.59; P < 0.001) and graft (hazard ratio, 0.62; P < 0.001) survival versus CNI monotherapy. The benefit of CNI plus antimetabolite on patient and graft survival increased with older age.

CONCLUSIONS

In this first longitudinal analysis of LT immunosuppression practices among Medicare beneficiaries, a CNI plus antimetabolite approach led to improved outcomes. Significant center heterogeneity in practice was observed.

Humoral Immunogenicity to SARS-CoV-2 Vaccination in Liver Transplant Recipients: A Systematic Review and Meta-Analysis

Solid organ transplant recipients generally show reduced immunogenicity to various vaccines. We aimed to assess the immunogenicity of the immune response among orthotopic liver transplant (OLT) recipients after the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. A systematic search was performed to evaluate immunogenicity or adverse events reported after SARS-CoV-2 vaccination. The pooled analysis of 20 studies showed a humoral immune response rate of 0.70 (95% confidence interval [CI], 0.63-0.77) after SARS-CoV-2 vaccination among OLT recipients. The immunogenicity among OLT recipients was significantly lower compared to the overall population and healthy controls, with odds ratios (ORs) of 0.80 and 0.69. However, it was significantly higher than that of patients receiving other organ transplants, especially kidneys, with an OR of 1.50. Male sex, old age, chronic kidney disease, obesity, and multiple or high immunosuppressant doses significantly increased the risk of unresponsiveness in patients with OLT. The overall incidence of any adverse event after vaccination was 0.68 (95% CI, 0.55-0.81), similar to that of control. OLT recipients had an overall humoral immune response rate of 70% after SARS-CoV-2 vaccination, which is lower than that of healthy controls but favourable compared to those of other solid organ transplant recipients.

Lost potential and missed opportunities for DCD liver transplantation in the United States

BACKGROUND

Donation after cardiac death(DCD) has been proposed as an avenue to expand the liver donor pool.

METHODS

We examined factors associated with nonrecovery of DCD livers using UNOS data from 2015 to 2019.

RESULTS

There 265 non-recovered potential(NRP) DCD livers. Blood type AB (7.8% vs. 1.1%) and B (16.9% vs. 9.8%) were more frequent in the NRP versus actual donors (p < 0.001). The median driving time between donor hospital and transplant center was similar for NRP and actual donors (30.1 min vs. 30.0 min; p = 0.689), as was the percentage located within a transplant hospital (20.8% vs. 20.9%; p = 0.984).The donation service area(DSA) of a donor hospital explained 27.9% (p = 0.001) of the variability in whether a DCD liver was recovered.

CONCLUSION

A number of potentially high quality DCD donor livers go unrecovered each year, which may be partially explained by donor blood type and variation in regional and DSA level practice patterns.

Renal function after liver transplantation: Real-world experience with basiliximab induction and delayed reduced-dose tacrolimus

BACKGROUND

Routine use of delayed reduced-dose calcineurin-inhibitor treatment with induction immunosuppression in liver transplantation to minimize post-operative kidney injury is still scarce.

AIM

To evaluate real-world experience of basiliximab induction with delayed reduced-dose tacrolimus.

METHODS

In a retrospective cohort study, kidney function was evaluated pre- and postoperatively by measured glomerular filtration rate (mGFR). Adult patients undergoing liver transplantation between 2000 and 2017 were divided into a conventional treatment group (immediate-introduction of tacrolimus, target trough levels 10-15 ng/mL, and corticosteroids, n = 203) and a revised treatment group (basiliximab induction, reduced-dose tacrolimus, target through levels 5-8 ng/mL, delayed until day three, and mycophenolate mofetil 2000 mg/day, n = 343).

RESULTS

Mean mGFR was similar between groups at wait-listing (85.3 vs 84.1 ml/min/1.73m², p = 0.60), but higher in the revised treatment group at 3 (56.8 vs 63.4 ml/min/1.73m², p = 0.004) and 12 months post-transplant (60.9 vs 69.7 ml/min/1.73m², p<0.001); this difference remained after correcting for multiple confounders and was independent of pre-transplant mGFR. In the revised treatment group, biopsy proven acute rejection rate was lower (38% vs. 21%, p<0.001), and graft-survival better (p = 0.01).

CONCLUSION

Basiliximab induction with delayed reduced-dose tacrolimus is associated with less kidney injury when compared to standard-dose tacrolimus, without increased risk of rejection, graft loss or death.

Center Variability in Acute Rejection and Biliary Complications After Pediatric Liver Transplantation

Transplant center performance and practice variation for pediatric post-liver transplantation (LT) outcomes other than survival are understudied. This was a retrospective cohort study of pediatric LT recipients who received transplants between January 1, 2006, and May 31, 2017, using United Network for Organ Sharing (UNOS) data that were merged with the Pediatric Health Information System database. Center effects for the acute rejection rate at 1 year after LT (AR1) using UNOS coding and the biliary complication rate at 1 year after LT (BC1) using inpatient billing claims data were estimated by center-specific rescaled odds ratios that accounted for potential differences in recipient and donor characteristics. There were 2216 pediatric LT recipients at 24 freestanding children's hospitals in the United States during the study period. The median unadjusted center rate of AR1 was 36.92% (interquartile range [IQR], 22.36%-44.52%), whereas that of BC1 was 32.29% (IQR, 26.14%-40.44%). Accounting for recipient case mix and donor factors, 5/24 centers performed better than expected with regard to AR1, whereas 3/24 centers performed worse than expected. There was less heterogeneity across the center effects for BC1 than for AR1. There was no relationship observed between the center effects for AR1 or BC1 and center volume. Beyond recipient and allograft factors, differences in transplant center management are an important driver of center AR1 performance, and less so of BC1 performance. Further research is needed to identify the sources of variability so as to implement the most effective solutions to broadly enhance outcomes for pediatric LT recipients.

Induction Therapy and Therapeutic Antibodies

Prevention of allograft rejection is one of the crucial goals in solid organ transplantation to ensure durability of the graft and is chiefly mediated by cellular and humoral pathways targeting cell surface alloantigens. The risk of rejection is highest in the first post-transplant year and wanes with time albeit the risk always exists and varies with the type of organ transplanted. Induction therapies refer to the use of high-intensity immunosuppression in the immediate post-operative period to mitigate the highest risk of rejection. This term encompasses chiefly the use of antibody therapies directed against one of the key pathways in T-cell activation or abrogating effects of circulating alloantibodies. These antibodies carry more potent immunomodulatory effect than maintenance immunosuppressive therapy alone and many of them lead to durable immune cell depletion. A variety of monoclonal and polyclonal antibodies have been utilized for use not only for induction therapy, but also for treatment of allograft rejection when it occurs and as components of desensitization therapy before and after transplantation to modulate circulating alloantibodies.

Predictive Factors for Humoral Response After 2-dose SARS-CoV-2 Vaccine in Solid Organ Transplant Patients

Background

A weak immunogenicity has been reported in solid organ transplant (SOT) recipients after 2 doses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. The aim of this retrospective study was to identify the predictive factors for humoral response in SOT patients.

Methods

Three hundred and ninety-three SOT patients from our center with at least 4 wk of follow-up after 2 doses of mRNA-based vaccine were included in this study. Anti-SARS-Cov-2 spike protein antibodies were assessed before and after vaccination.

Results

Anti-SARS-CoV-2 antibodies were detected in 34% of the patients: 33.7% of kidney transplant patients, 47.7% of liver transplant patients, and 14.3% of thoracic transplant patients (P = 0.005). Independent predictive factors for humoral response after vaccination were male gender, a longer period between transplantation and vaccination, liver transplant recipients, a higher lymphocyte count at baseline, a higher estimated glomerular filtration rate and receiving the tacrolimus + everolimus ± steroids combination. Conversely, the nondevelopment of anti-SARS-CoV-2 antibodies after vaccination was associated with younger patients, thoracic organ recipients, induction therapy recipients, and tacrolimus + mycophenolic acid ± steroids recipients.

Conclusions

The immunosuppressive regimen is a modifiable predictive factor for humoral response to SARS-CoV-2 vaccine.

Differences in Early Immunosuppressive Therapy Among Liver Retransplantation Recipients in a National Cohort

BACKGROUND

There is no unified consensus as to the preferred immunosuppression (IS) strategy following liver retransplantation (reLT).

METHODS

This was a retrospective cohort study using the United Network for Organ Sharing database. Recipient, donor, and center characteristics associated with induction use and early maintenance IS regimen were described. Multivariable Cox proportional hazards analysis evaluated induction receipt as a predictor of post-reLT survival.

RESULTS

There were 3483 adult reLT recipients from 2002 to 2018 at 116 centers with 95.6% being performed at the same center as the initial liver transplant. Timing of reLT was associated with induction IS use and the discharge regimen (P < 0.001 for both) but not with regimens at 6- and 12-month post-reLT (P = 0.1 for both). Among late reLTs (>365 d), initial liver disease cause was a more important determinant of maintenance regimen than graft failure cause. Low-reLT volume centers used induction more often for late reLTs (41.1% versus 22.6% high volume; P = 0.002) yet were less likely to wean to calcineurin inhibitors alone in the first year (19.1% versus 38.7% high volume; P = 0.002). Accounting for recipient and donor factors, depleting induction marginally improved post-reLT mortality (adjusted hazard ratio, 0.77; 95% CI, 0.61-0.99; P = 0.08), whereas nondepleting induction had no significant effect.

CONCLUSIONS

Although several recipient attributes inform early IS decision-making, this does not occur in a uniform manner and center factors also play a role. Further studies are needed to assess the effect of early IS on post-reLT outcomes.

Induction Therapy With Antithymocyte Globulin and Delayed Calcineurin Inhibitor Initiation for Renal Protection in Liver Transplantation: A Multicenter Randomized Controlled Phase II-B Trial

BACKGROUND

Calcineurin inhibitor (CNI) based immunosuppression in liver transplantation (LTx) is associated with acute and chronic deterioration of kidney function. Delaying CNI initiation by using induction rabbit anti-thymocyte globulin (rATG) may provide kidneys with adequate time to recover from a perioperative insult reducing the risk of early post-LTx renal deterioration.

METHODS

This was an open-label, multicenter, randomized controlled clinical trial comparing use of induction rATG with delayed CNI initiation (day-10) against upfront CNI commencement (SOC; standard of care) in those patients deemed at standard risk of postoperative renal dysfunction following LTx. The primary end point was change in (delta) creatinine from baseline to month-12.

RESULTS

Fifty-five patients were enrolled in each study arm. Mean Tacrolimus levels remained comparable in both groups from day-10 throughout the study period. A significant difference in delta creatinine was observed between rATG and SOC groups at 9-months (p=0.03) but not at month-12 (p=0.05). eGFR levels remained comparable between cohorts at all time points. Rates of biopsy-proven acute rejection at 1-year were similar between groups (16.3 vs 12.7%, p= 0.58). rATG showed no significant adverse effects. Survival at 12-months was comparable between groups (p= 0.48).

CONCLUSIONS

Although the use of induction rATG and concurrent CNI deferral in this study did not demonstrate a significant difference in delta creatinine at 1 year, these results indicate a potential role for rATG in preserving early kidney function, especially when considered with CNI deferral beyond 10 days and/or lower target Tacrolimus levels, with acceptable safety and treatment efficacy.

A Learning Health System for Pediatric Liver Transplant: The Starzl Network for Excellence in Pediatric Transplantation

OBJECTIVE

Learning health systems (LHS) integrate research, improvement, management, and patient care, such that every child receives "the right care at the right time...every time," that is, evidence-based, personalized medicine. Here, we report our efforts to establish a sustainable, productive, multicenter LHS focused on pediatric liver transplantation.

METHODS

The Starzl Network for Excellence in Pediatric Transplantation (SNEPT) is the first multicenter effort by pediatric liver transplant families and providers to develop shared priorities and a shared agenda for innovation in clinical care. This report outlines SNEPT's structure, accomplishments, and challenges as an LHS.

RESULTS

We prioritized 4 initial projects: immunosuppression, perioperative anticoagulation, quality of life, and transition of care. We shared center protocols/management to identify areas of practice variability between centers. We prioritized actionable items that address barriers to providing "the right care at the right time" to every pediatric liver transplant recipient: facilitating transparency of practice variation and the connection of practices to patient outcomes, harnessing existing datasets to reduce the burden of tracking outcomes, incorporating patient-reported outcomes into outcome metrics, and accelerating the implementation of knowledge into clinical practice. This has allowed us to strengthen collaborative relationships, design quality improvement projects, and collect pilot data for each of our priority projects.

CONCLUSIONS

The field of pediatric liver transplantation can be advanced through application of LHS principles. Going forward, SNEPT will continue to unite patient advocacy, big data, technology, and transplant thought leaders to deliver the best care, while developing new, scalable solutions to pediatric transplantation's most challenging problems.

Identification of peripheral CD154+ T cells and HLA-DRB1 as biomarkers of acute cellular rejection in adult liver transplant recipients

Decreasing graft rejection and increasing graft and patient survival are great challenges facing liver transplantation (LT). Different T cell subsets participate in the acute cellular rejection (ACR) of the allograft. Cell-mediated immunity markers of the recipient could help to understand the mechanisms underlying acute rejection. This study aimed to analyse different surface antigens on T cells in a cohort of adult liver patients undergoing LT to determine the influence on ACR using multi-parametric flow cytometry functional assay. Thirty patients were monitored at baseline and during 1 year post-transplant. Two groups were established, with (ACR) and without (NACR) acute cellular rejection. Leukocyte, total lymphocyte, percentages of CD4+ CD154+ and CD8+ CD154+ T cells, human leukocyte antigen (HLA) mismatch between recipient-donor and their relation with ACR as well as the acute rejection frequencies were analysed. T cells were stimulated with concanavalin A (Con-A) and surface antigens were analysed by fluorescence activated cell sorter (FACS) analysis. A high percentage of CD4+ CD154+ T cells (P = 0·001) and a low percentage of CD8+ CD154+ T cells (P = 0·002) at baseline were statistically significant in ACR. A receiver operating characteristic analysis determined the cut-off values capable to stratify patients at high risk of ACR with high sensitivity and specificity for CD4+ CD154+ (P = 0·001) and CD8+ CD154+ T cells (P = 0·002). In logistic regression analysis, CD4+ CD154+ , CD8+ CD154+ and HLA mismatch were confirmed as independent risk factors to ACR. Post-transplant percentages of both T cell subsets were significantly higher in ACR, despite variations compared to pretransplant. These findings support the selection of candidates for LT based on the pretransplant percentages of CD4+ CD154+ and CD8+ CD154+ T cells in parallel with other transplant factors.

Nationwide variability in the use of induction immunosuppression for adult heart transplantation

BACKGROUND

Institutional factors have been shown to impact outcomes following orthotopic heart transplantation (OHT). This study evaluated center variability in the utilization of induction therapy for OHT and its implications on clinical outcomes.

METHODS

Adult OHT patients between 2010 and 2018 were identified from the United Network for Organ Sharing registry. Transplant centers were stratified based on their rates of induction therapy utilization. Mixed-effects logistic regression models were created with drug-treated rejection within 1 year as primary endpoint and individual centers as a random parameter. Risk-adjusted Cox regression was used to evaluate patient-level mortality outcomes.

RESULTS

In 17,524 OHTs performed at 100 centers, induction therapy was utilized in 48.6% (n = 8411) with substantial variability between centers (interquartile range, 21.4%-79.1%). There were 36, 30, and 34 centers in the low (<29%), intermediate (29%-66%), and high (>67%) induction utilization terciles groups, respectively. Induction therapy did not account for the observed variability in the treated rejection rate at 1 year among centers after adjusting for donor and recipient factors (p = .20). No differences were observed in postoperative outcomes among induction utilization centers groups (all, p > .05). Furthermore, there was a weak correlation between the percentage of induction therapy utilization at the center-level and recipients found to have moderate (r = .03) or high (r = .04) baseline risks for acute rejection at 1 year.

CONCLUSIONS

This analysis demonstrates that there is substantial variability in the use of induction therapy among OHT centers. In addition, there was a minimal correlation with baseline recipient risk or 1-year rejection rates, suggesting a need for better-standardized practices for induction therapy use in OHT.

Immunosuppression in Donation After Circulatory Death Liver Transplantation: Can Induction Modify Graft Survival?

Recipients of donation after circulatory death (DCD) LTs historically have an increased risk of graft failure. Antibody induction (AI) with antithymocyte globulin (ATG) or anti-interleukin 2 receptor (anti-IL2R) immunotherapy may decrease the incidence of graft failure by mitigating ischemia/reperfusion injury. A retrospective review of the United Network for Organ Sharing (UNOS) database for LTs between 2002 and 2015 was conducted to determine whether ATG or anti-IL2R AI was associated with graft survival in DCD. A secondary endpoint was postoperative renal function as measured by estimated glomerular filtration rate at 6 and 12 months. Among DCD recipients, ATG (hazard ratio [HR] = 0.71; P = 0.03), but not anti-IL2R (HR = 0.82; P = 0.10), was associated with a decrease in graft failure at 3 years when compared with recipients without AI. ATG (HR = 0.90; P = 0.02) and anti-IL2R (HR = 0.94; P = 0.03) were associated with a decreased risk of graft failure in donation after brain death (DBD) liver recipients at 3 years compared with no AI. When induction regimens were compared between DCD and DBD, only ATG (HR = 1.19; P = 0.19), and not anti-IL2R (HR = 1.49; P < 0.01) or no AI (HR = 1.77; P < 0.01), was associated with similar survival between DCD and DBD. In conclusion, AI therapy with ATG was associated with improved longterm liver allograft survival in DCD compared with no AI. ATG was associated with equivalent graft survival between DCD and DBD, suggesting a beneficial role of immune cell depletion in DCD outcomes.