Anti-thymocyte globulin induction with delayed introduction of tacrolimus preserves renal function in pediatric liver transplant recipients

Background

Tacrolimus (TAC)-mediated renal disease occurs in up to 70% of pediatric liver transplant (LT) recipients. The safety and efficacy of renal-sparing immunosuppression using anti-thymocyte globulin (ATG) induction and delayed TAC administration has not been studied in children. We evaluated the safety and efficacy of ATG induction on preserving renal function in children within the first year (Y1) post-LT in a single-center retrospective cohort study.

Methods

Children under age 18 years of who received isolated LT from 2008 to 2020 with a GFR < 70 received renal-sparing (RS) protocol consisting of ATG with methylprednisolone (MP), delayed TAC administration, lower initial TAC trough goals, and mycophenolate mofetil (MMF). The RS group was matched 1:2 by age and LT indication with standard immunosuppression (SI) group. Changes in renal function as well as adverse events within Y1 post-LT were compared.

Results

Forty-four pediatric patients were included in the analysis, of which 13 received RS. As expected, the RS group had significantly lower mean TAC trough levels at 30 days (10.3 vs. 13.2, p = .001) post-LT. Renal function was significantly preserved at 6 (−0.26 vs. 0.21, p = .004) and 12 months (−0.33 vs. 0.11, p = .003) post-LT in the RS versus SI group as measured by mean change in serum creatinine, with similar trends observed in eGFR and cystatin C. ACR, sepsis, viremia, graft loss and mortality occurred at similar rates in both RS and SI groups.

Conclusion

Induction immunosuppression with ATG and delayed TAC administration in children with renal impairment is safe and effectively preserves renal function during Y1 post-LT.     

Efficacy and pharmacokinetics of tacrolimus oral suspension in pediatric liver transplant recipients

The use of tacrolimus in small pediatric graft recipients may require the availability of a suspension formulation for appropriate dose titration and easier administration. The pharmacokinetics (Pk) of an extemporaneously prepared oral suspension of tacrolimus (OST) was investigated in 15 pediatric liver transplant recipients, and was compared with the corresponding data with tacrolimus capsules (TC). Graft and patient survival rates were 100%. Acute rejection and steroid-resistant rejection were encountered in 9/15 and 3/15 patients, respectively. Comparison of Pk data showed a lower oral absorption of OST when compared with TC. No significant correlation could be made between the Pk parameters and rejection. Despite the lower bioavailability of OST when compared with TC, the rejection incidence was similar with both formulations (60% vs. 55%, respectively). Accordingly, the use of OST may constitute an alternative option for tacrolimus administration in low body weight organ recipients, to allow dosage titration in the early post-transplant weeks.     

Presentation of atopic disease in a large cohort of pediatric liver transplant recipients

Atopic disease occurs in solid organ transplant recipients with an increasingly recognized frequency. The time course for the development of these atopic diseases in liver transplantation has not been described. The objective was to characterize the atopic manifestations of children receiving chronic immunosuppression after orthotopic liver transplantation (OLT). Chart review and follow-up questionnaire were utilized for 176 OLT pediatric recipients at a single institution for manifestations of allergic disease. Atopic disease was present in 25 (14.2%) patients. Median age at transplant was 16 months with a median follow-up of 63 months. Food allergy and non-food related atopic symptoms presented at a median of 11.5 (IQR, 6-28) and 19 (IQR, 5-41) months post-transplantation, respectively. The median age at transplant of the non-atopic children was 72 months, higher than patients with atopy (p < 0.001). Food allergy and atopic skin disease symptoms were present in 40% and 56% of cases, respectively. Asthma, allergic rhinitis, or both were found in 66% of cases. The onset of symptoms of food allergy and eczema (median, 12 months post-transplantation) preceded symptoms of allergic rhinitis and asthma. (median of 27 and 30 months post-transplantation, respectively). Atopy occurs in ～14% of pediatric liver transplant recipients, with manifestations including food allergy, eczema, allergic rhinitis, and asthma.     

Therapeutic drug monitoring of tacrolimus in pediatric liver transplant patients

The clinical utility of tacrolimus monitoring in adults has been well documented. The present study compared tacrolimus monitoring in a pediatric population of 34 liver transplant patients in four US centers with an adult population of 111 patients in six US centers. Subjects (adult and pediatric) were evaluated, at defined intervals over 12 weeks post-transplantation (Tx), for tacrolimus trough concentrations and 12 additional laboratory chemistries. Pediatric patient and graft survival for the 12 weeks were 91% and 88%, respectively, as compared to 97% and 93%, respectively, for the adult population. The mean oral dosage of tacrolimus for pediatric patients was 0.13 +/- 0.1 mg/kg/day at week 1, increased to 0.30 +/- 0.3 mg/kg/day by week 3 and remained constant for the remainder of the study. These dosages were two- to three-fold higher than the dosage used in the adult population. In contrast, the mean whole-blood trough concentration, as determined by PRO-Tractrade mark II enzyme-linked immunosorbent assay (ELISA), decreased from 11.3 +/- 5.1 ng/mL at week 1 to 6.3 +/- 3.7 ng/mL by week 12 and was not significantly different from the trough concentration in adults. The incidence and distribution of the clinical end-points for the pediatric subjects (rejection, nephrotoxicity, death, re-Tx) were different from those observed in adults. The total percentage of pediatric subjects reaching any end-point was 74%, as compared to 54% in the adult population. These data indicate several differences between the adult and pediatric populations in their response to tacrolimus.     

Intra-patient variability in tacrolimus trough concentrations and renal function decline in pediatric renal transplant recipients

Prytula AA, Bouts AH, Mathot RAA, van Gelder T, Croes LK, Hop W, Cransberg K. Intra‐patient variability in tacrolimus trough concentrations and renal function decline in pediatric renal transplant recipients. Abstract: High intra‐patient variability in TCL exposure is a risk factor for allograft loss and late acute rejection. We hypothesized that a higher intra‐patient variability leads to a faster decline in GFR in pediatric renal transplant patients and that adolescents have a higher intra‐patient variability due to poorer adherence. We included 69 children aged 3.5–18 yr who had undergone renal transplantation between April 1996 and May 2009 in two pediatric nephrology centers in the Netherlands. We analyzed TCL trough concentrations over a period of one yr and calculated TCL trough concentrations variability using VC. We investigated the correlation between the TCL trough concentrations variability and the decline in estimated GFR over four yr. The median intra‐patient variability in TCL concentrations was 30.1% (range 8.6–77.6) and the mean GFR slope ?3.8 mL/min/1.73 m²/yr. The VC correlated neither with the GFR slope, nor with the patients’ age. However, children with late acute rejection had higher VC (p = 0.045). We were unable to provide evidence that a high variability in TCL exposure leads to a faster decline in renal function, although children with late acute rejection have a higher variability in TCL exposure. Adolescents do not have a higher intra‐patient variability in TCL trough concentrations than younger children.     

Alemtuzumab induction with tacrolimus monotherapy in 25 pediatric renal transplant recipients

ALA induction in transplantation has been shown to reduce the need for maintenance immunosuppression. We report the outcome of 25 pediatric renal transplants between 2007 and 2010 using ALA induction followed by tacrolimus maintenance monotherapy. Patient ages were 1–19 yr (mean 14 ± 4.1 yr). Time of follow‐up was 7–51 months (mean 26 ± 13 months). Tacrolimus monotherapy was maintained in 48% of patients, and glucocorticoids were avoided in 80% of recipients. Mean plasma creatinine and GFR at one yr post‐transplant were 0.88 ± 0.3 mg/dL and 104.4 ± 25 mL/min/1.73m², respectively. One, two, and three‐yr actuarial patient and graft survival rates were 100%. The incidence of early AR (<12 months after transplantation) was 12%, while the incidence of late AR (after 12 months) was 16%. Forty‐four percent of the recipients recovered normal, baseline renal function after an episode of AR, and 44% had persistent renal dysfunction (plasma creatinine 1.0–1.8 mg/dL). One graft was lost four yr after transplantation due to medication non‐compliance. Four (16%) patients developed BK or CMV infection. In our experience, ALA induction with tacrolimus monotherapy resulted in excellent short‐ and mid‐term patient and graft survival in low‐immunologic risk pediatric renal transplant recipients.     

Towards minimizing immunosuppression in pediatric liver transplant recipients

Abstract:  Immunosuppression regimens after liver transplantation focus mainly on preventing rejection and subsequent graft loss. However, in children, morbidity and mortality rates from infections exceed those from rejection after transplant, and immunosuppression can hinder growth, renal function, and graft tolerance. We hypothesized that early steroid withdrawal, with a primary aim of TAC monotherapy would yield no penalty in terms of rejection and graft loss, while reducing risks of infection and maximizing growth. We prospectively evaluated 64 consecutive pediatric liver transplant recipients. One yr patient/graft survival was 93/90%, respectively. At one yr post-transplant, 75.4% of patients were on TAC monotherapy. No deaths or graft losses were caused by infection. Sixty-one percent of patients had at least one episode of rejection, most within three months following transplant and 3.8% were treated for chronic rejection. One non-compliant adolescent died from chronic rejection. CMV, EBV, and lymphoproliferative disease rates were 3.1%, 5.3%, 1.8%, respectively. Pretransplant and one yr post-transplant glomerular filtration rates were unchanged. One yr improved catch-up growth was observed. We conclude that immunosuppression minimization after pediatric liver transplant yields no serious complications from rejection, and might confer advantages with respect to infection, renal function, growth, and is deserving of wider application and study.     

Primary tacrolimus (FK506) therapy and the long-term risk of post-transplant lymphoproliferative disease in pediatric liver transplant recipients

While the overall incidence of post-transplant lymphoproliferative disease (PTLD) in pediatric liver transplant recipients has been reported to be 4-11%, the long-term risk of PTLD associated with primary tacrolimus therapy is unknown. Therefore, in order to determine the incidence and long-term risk of PTLD, the present study examined 131 pediatric recipients who underwent liver transplantation (LTx) between October 1989 and December 1991 and received primary tacrolimus therapy. This cohort of children was evaluated over an extended time-period (until December 31 1996) with a mean follow-up of 6.3 yr. Actuarial Kaplan-Meier analysis was utilized to determine the risk of PTLD over time. The overall incidence of PTLD was 13% (17/131) with an average age of 4.3 +/- 0.75 yr at diagnosis. Pretransplant Epstein-Barr virus (EBV) serologies were negative in 82%, positive in 12%, and not available in 6% of the patients. The median time to diagnosis of PTLD post-Tx was 11.9 months (mean 16.4 +/- 3.9, range 1.7-63.0 months). Mean tacrolimus dose and plasma trough level (as evaluated by enzyme-linked immunosorbent assay [ELISA]) at the time of diagnosis was 0.32 +/- 0.06 mg/kg/day and 1.3 +/- 0.3 ng/mL, respectively. The cumulative long-term risk of PTLD was found to increase over time: 3% at 6 months, 8% at 1 yr, 12% at 2 yr, 14% at 3 yr, and 15% at 4 and 5 yr. Mortality from PTLD was 12% (two of 17 patients). Primary tacrolimus use in pediatric LTx has a long-term risk of PTLD approaching 15%, with the majority of episodes (78%) occurring in the first 2 yr, suggesting that intense EBV surveillance should occur early post-transplantation.     

Early post‐operative intravenous tacrolimus in pediatric liver transplant recipients is not superior to oral tacrolimus

We aimed to compare the early results of i.v. with p.o. TAC as a primary immunosuppressant in pediatric patients undergoing LT. This retrospective study enrolled 75 children who underwent LT and received TAC‐steroid regimens as a primary immunosuppressant between September 2011 and October 2015 at our institution. Thirty‐five recipients received TAC i.v. and 40 received TAC p.o. Early results were evaluated and compared, including ACR, EBV, or CMV infection; renal adverse effects; and hospital stay. Comparisons of 90‐day post‐transplant results showed that the rates of overall viral (74% vs 40% P < 0.002), EBV (46% vs 17.5% P < 0.008), and CMV (51% vs 30% P = 0.05) infections were significantly higher in the i.v. than in the p.o. group. Neither regimen has any adverse effects on renal function. There were no between‐group differences in ACR incidence and severity, serum creatinine concentration, and hospital stay. Patient and graft survival rates at 3 months and 1 year did not differ significantly between the two groups. Compared with p.o. treatment, i.v. administration of high TAC concentration did not have beneficial post‐transplant effects on ACR incidence and severity, while increasing the incidence of viral infections in pediatric LT.     

Food protein sensitivity with partial villous atrophy after pediatric liver transplantation with tacrolimus immunosuppression

We report three pediatric liver transplant recipients receiving tacrolimus immunosuppression presented with vomiting, heme-positive stools and failure to thrive, who had subtotal villous atrophy in their histology because of food protein sensitivity. Case findings and current literature of the casual relationship between tacrolimus and food allergies briefly reviewed.     

Calcineurin inhibitor minimization in pediatric liver allograft recipients

Abstract:  The use of CNI in pediatric LTx has dramatically improved the outcome for children with end-stage liver disease by significantly reducing the rate of acute and chronic rejection. Long-term concerns about CNI-induced nephrotoxicity and other adverse effects remain an issue, particularly as the emphasis moves from short-term survival to long-term quality of life. This review summarizes lessons learnt from pediatric and adult solid organ transplantation in minimizing CNI use in immunosuppression protocols in children following LTx. There are three models for CNI minimization: dose reduction, withdrawal or avoidance, supplemented by the use of IL-2 receptor blocking antibodies in the peri-transplant period, and early transition to alternate drugs such as MMF or SRL. Prospective studies evaluating reduction or withdrawal protocols in adult and pediatric LTx indicate that rejection rates are comparable with traditional CNI-based immunosuppression and that two and five yr patient and graft survival are similar, with recovery in renal function. There are few studies evaluating complete avoidance of CNI, apart from that in renal transplantation, although the benefits of long-term reduction in cardiovascular, metabolic, and possibly neoplastic side effects may justify this approach. It is not clear yet how CNI minimization will affect the development of tolerance but experimental and preliminary clinical studies indicate that CNI and steroid avoidance or minimization in the peri-operative period may favor the development of long-term graft tolerance. In summary, CNI minimization may be safe and effective in the short term but large-scale pediatric randomized studies are required to evaluate the long-term efficacy of these regimes in the development of chronic rejection, PTLD, and graft tolerance.     

Treatment of acute tacrolimus whole-blood elevation with phenobarbital in the pediatric liver transplant recipient

The toxicities associated with the chronic use of tacrolimus are well described in the literature; however, little is known about the management during an acute overdose. Phenobarbital is a long-acting barbiturate metabolized in the liver by the cytochrome p450 3a4 system. It is known to enhance the rate of metabolism of itself and the clearance of drugs metabolized by p450 3a4. Because tacrolimus is a substrate of this particular isoenzyme, phenobarbital can be considered a potential option when rapid decreases in tacrolimus whole-blood levels are desired. We hereby report our experience using intravenous phenobarbital in the management of two infants with acute elevations in their tacrolimus whole-blood concentration following liver transplantation. Phenobarbital, through its up-regulation of hepatic cytochrome p450 system increases the elimination of whole-blood tacrolimus concentration in acute overdose situations.     

Pharmacoepidemiology of tacrolimus in pediatric liver transplantation

AEs during immunosuppressive treatment with tacrolimus are very common. We retrospectively evaluated FK safety and efficacy in a large pediatric liver transplant cohort in Latin America. During 2‐year follow‐up, we analyzed data from patients who underwent liver transplantation over the period 2010‐2012 and recorded FK exposure, AEs, and AR episodes. AEs were classified according causality and severity. Tacrolimus exposure before and during AE was compared using Wilcoxon matched‐pairs test. Kaplan‐Meier curves were used for survival analysis. In total, 46 patients (out of 72 patients) experienced 69 AEs, such as hypomagnesemia (49%), PTLD (6%), hypertension (6%), and/or nephrotoxicity (22%). 43% of AEs were classified as moderate or serious, and 89% were assigned as probable or definitive. Patients who had one or more AR episodes accounted for 65%. The 12‐month acute rejection‐free survival was 41% (95% CI, 30.1%‐53.1%). A significant difference was observed in FK trough concentrations before and during hypomagnesemia and nephrotoxicity (P<.05). This study is the first report of FK safety in a large group of pediatric liver transplant patients in Latin America. Children experience AEs, even in protocols with low FK doses. Therapeutic monitoring is an important tool to manage immunosuppressive schemes containing tacrolimus in vulnerable populations.     

Conversion from cyclosporin A to tacrolimus in pediatric liver transplantation

The dosing regimen for conversion from cyclosporin A (CsA) to tacrolimus immunosuppression was studied in 12 pediatric liver allograft recipients. Patients were stratified according to their age. Tacrolimus was started orally at a dosage of 0.05 mg/kg b.i.d., 12 h after stopping CsA administration and increased thereafter if needed. Tacrolimus and CsA concentrations were assayed by immunoassay using, respectively, an IMx and a TDx autoanalyzer (Abbott-France). Mean CsA concentration was in the therapeutic range 12 h prior to and at the time of introduction of tacrolimus. After 72 h of tacrolimus therapy, CsA concentrations were undetectable whereas mean tacrolimus concentration was 10.4 ng/mL with a mean dose of 0.09 mg/ kg b.i.d. The decline of CsA concentration was clearly biphasic. A slower decline in CsA concentration was detected after initiation of tacrolimus therapy, suggesting an inhibition of CsA metabolism by tacrolimus. No nephrotoxicity was observed. This dosage regimen allowed effective immunosuppression while avoiding additive nephrotoxicity.     

Lipid profile and cardiovascular risk factors in pediatric liver transplant recipients

Cardiovascular diseases induce long‐term morbidity and mortality of adult LT recipients. The aim of this retrospective study was to assess CVRF, lipid abnormalities, and atherosclerosis (appraised by c‐IMT), more than 10 yr after pediatric LT. Thirty‐one children who underwent LT between December 1990 and December 2000 were included. Median age at LT was 14 months (range 4–64), and median follow‐up after LT was 11.9 yr (range 9.0–17.3). In our cohort, obesity (9.7%) and treated hypertension (9.7%) were rare. None of the patients was smoker or diabetic. High TC and TG were both observed in 6.5% of the patients. The mean c‐IMT for male patients was 1.22 ± 1.55 and 1.58 ± 1.23 mm in female patients. Seven patients (22%) had a mean c‐IMT above +2 s.d. Values below the 5th percentile were noted for LDL‐cholesterol (58.1%), HDL‐cholesterol (25.8%), apolipoprotein B (40%), and apolipoprotein A1 (20%). LDL‐cholesterol and apolipoprotein B levels were significantly lower in patients treated by tacrolimus in comparison with CsA (p < 0.05). In conclusion, our results suggest that pediatric LT patients do not present significant CVRF; moreover, instead of hyperlipidemia, hypocholesterolemia (LDL‐C) is frequent and immunosuppressive therapy is probably the cause.     

Comparative pharmacokinetics of tacrolimus in stable pediatric allograft recipients converted from immediate‐release tacrolimus to prolonged‐release tacrolimus formulation

This study was a Phase II, open‐label, multicenter, single‐arm, cross‐over study comparing the pharmacokinetics (PK) of tacrolimus in stable pediatric kidney, liver, or heart allograft recipients converted from immediate‐release tacrolimus (IR‐T) to prolonged‐release tacrolimus (PR‐T). In Days ?30 to ?1 of screening period, patients received their IR‐T‐based regimen; during Days 1‐7, patients received study IR‐T (same dose as screening). On Day 7, the first 24‐hours PK profile was taken; patients were then converted to PR‐T (1 mg:1 mg), with a second 24‐hours PK profile taken on Day 14. The primary end‐point was tacrolimus area under the blood concentration–time curve over 24 hours (AUC₂₄); secondary end‐points were maximum concentration C_maxand concentration at 24 hours C₂₄. The predefined similarity interval for confidence intervals (CIs) of least squares mean (LSM) ratios was 80%‐125%. The PK analysis set comprised 74 pediatric transplant recipients (kidney, n = 45; liver, n = 28; heart, n = 1). PR‐T:IR‐T LSM ratio (90% CI) was similar overall for AUC₂₄, _max, and C₂₄, and for kidney and liver recipients for AUC₂₄ (LSM ratio, kidney 91.8%; liver 104.1%) and C₂₄ (kidney 90.5%; liver 89.9%). Linear relationship was similar between AUC₂₄ and C₂₄, and between PR‐T and IR‐T (rho 0.89 and 0.84, respectively), suggesting that stable pediatric transplant recipients can be converted from IR‐T to PR‐T at the same total daily dose, using the same therapeutic drug monitoring method.     

Cold agglutinin syndrome in pediatric liver transplant recipients

Anemia is a common finding in post-liver transplant patients. Causes for the anemia include nutritional deficiencies, red cell aplasia as well as immune-mediated hemolysis. One of the immunologic causes of hemolytic anemia is drug-induced hemolysis. Tacrolimus is a common immunosuppressant used in post-liver transplant patients to prevent graft rejection. There have been reports of tacrolimus-associated hemolytic anemia secondary to hemolytic uremic syndrome as well as autoimmune hemolysis. There are also case-reports of severe hemolytic anemia related to cold agglutinin production in post-liver transplant patients. We described in this paper three cases of severe cold agglutinin hemolytic anemia in three pediatric liver transplant patients. Steroid therapy, plasmapheresis and withdrawal of tacrolimus led to resolution of the severe hemolytic process in each case. Whether the immune-mediated hemolysis is related to tacrolimus is not clear and needs to be characterized further.     

Supra‐therapeutic tacrolimus concentrations associated with concomitant nicardipine in pediatric liver transplant recipients

Tacrolimus is prescribed to prevent allograft rejection in pediatric liver transplant recipients; however, its metabolism through the cytochrome P‐450 enzyme system presents a multitude of challenges in regard to drug interactions. Here, we describe four children (ages 1.4–8.7 yr) who acutely developed supra‐therapeutic serum tacrolimus trough concentrations, despite standard dosing, while on concomitant nicardipine therapy following liver transplantation. Even though tacrolimus regimens were altered (dosage reductions and held doses), serum tacrolimus concentrations remained elevated. Resolution of high tacrolimus concentrations was achieved only after the discontinuation of nicardipine. Following the termination of nicardipine, all children eventually required dosage increases in their tacrolimus regimens to re‐achieve target serum concentrations. We conclude that concomitant use of tacrolimus and nicardipine can result in high tacrolimus concentrations due to the inhibition of cytochrome p450 enzymes responsible for the metabolism of tacrolimus. We encourage clinicians to consider alternative antihypertensive options in children on tacrolimus therapy. If nicardipine therapy is necessary, we recommend a 50% reduction in tacrolimus dose and daily serum concentration monitoring.