Stable Liver Transplant Recipients Research Articles

A Pilot Study on the Safety and Efficacy of Generic Mycophenolate Agent as Conversion Maintenance Therapy in Stable Liver Transplant Recipients

PurposeThe patent covering mycophenolate mofetil (MMF) in Korea has expired and, thus, several generic MMF agents are now commercially available. The supply of Cellcept (Roche Korea) was interrupted at the end of 2011, so it was inevitable that a generic MMF would be used instead. During this period, we performed a prospective pilot study to examine the safety and efficacy of a generic mycophenolate agent (Myconol: Hanmi Pharmaceutical, Seoul Korea) for use as conversion maintenance therapy in stable liver transplantation (OLT) recipients. MethodsOLT recipients, who were treated with MMF on an outpatient basis from January 2012 to March 2012, attended follow-up interviews conducted. The patients had undergone OLT ≥ 2 years before the study, had tolerated Cellcept, and showed stable liver function. Fifty-three patients were followed up for more than 3 months after conversion to the same dose of Myconol. ResultsAfter conversion to Myconol, 6 patients (11.3%) experienced new side effects, which disappeared when they reverted to Cellcept (n = 5) or stopped taking Myconol medication (n = 1). The side effects associated with Myconol included gastrointestinal symptoms (indigestion and diarrhea; n = 3), skin eruptions (n = 1), pruritus (n = 1), and insomnia (n = 1). The mean mycophenolic acid levels were 1.71 ± 0.88 μg/mL for Cellcept and 1.83 ± 0.91 μg/mL for Myconol, which showed a strong correlation (r2 = 0.92, P < .001). ConclusionsMyconol showed similar pharmacokinetics to those of Celcept, but a small proportion of patients experienced agent-specific side effects; therefore, patients should be closely monitored when taking Myconol. Also, further studies, with a greater number of patients, are required to identify the full spectrum of drug-associated side effects.

Prospective multicenter clinical trial of immunosuppressive drug withdrawal in stable adult liver transplant recipients

Lifelong immunosuppression increases morbidity and mortality in liver transplantation. Discontinuation of immunosuppressive drugs could lessen this burden, but the safety, applicability, and clinical outcomes of this strategy need to be carefully defined. We enrolled 102 stable liver recipients at least 3 years after transplantation in a single-arm multicenter immunosuppression withdrawal trial. Drugs were gradually discontinued over a 6 to 9-month period. The primary endpoint was the development of operational tolerance, defined as successful immunosuppressive drug cessation maintained for at least 12 months with stable graft function and no histopathologic evidence of rejection. Out of the 98 recipients evaluated, 57 rejected and 41 successfully discontinued all immunosuppressive drugs. In nontolerant recipients rejection episodes were mild and resolved over 5.6 months (two nontolerant patients still exhibited mild gradually improving cholestasis at the end of follow-up). In tolerant recipients no progressive clinically significant histological damage was apparent in follow-up protocol biopsies performed up to 3 years following drug withdrawal. Tolerance was independently associated with time since transplantation (odds ratio [OR] 1.353; P = 0.0001), recipient age (OR 1.073; P = 0.009), and male gender (OR 4.657; P = 0.016). A predictive model incorporating the first two clinical variables identified subgroups of recipients with very high (79%), intermediate (30%-38%), and very low (0%) likelihood of successful withdrawal. When conducted at late timepoints after transplantation, immunosuppression withdrawal is successful in a high proportion of carefully selected liver recipients. A combination of clinical parameters could be useful to predict the success of this strategy. Additional prospective studies are now needed to confirm these results and to validate clinically applicable diagnostic biomarkers.

Conversion from twice daily tacrolimus to once daily tacrolimus in long-term stable liver transplant recipients: A single-center experience with 394 patients

After organ transplantation, strategies for simplifying the therapeutic regimen may improve adherence and prevent acute organ rejection and/or late graft loss. The aim of the present study was to evaluate the safety and efficacy of conversion from a tacrolimus (TAC) twice daily (bid) formulation to a once daily (qd) formulation in a large cohort of adult liver transplantation (LT) patients. This retrospective, observational, single-center study included 394 LT patients with at least 6 months' posttransplant follow-up and no rejection episodes in the last 3 months. The conversion from a bid formulation to a qd formulation was based on a 1:1 ratio. The mean age at the time of conversion was 53 years (range = 18-72 years); 66% were men. The main indication for LT was alcoholic cirrhosis (41%). The mean conversion time after LT was 74 months (range = 6-218 months). The mean serum TAC trough level decreased after conversion (6.1 ± 5.6 ng/mL before conversion versus 4.9 ± 2.5 ng/mL after conversion, P < 0.05). After a mean follow-up of 24 months after conversion, 6 patients had converted to cyclosporine, 14 patients had stopped all calcineurin inhibitors, 16 patients had returned to TAC bid, and 358 patients were still on TAC qd. Acute rejection episodes were observed in 7 patients. In conclusion, the results of our experience indicate that the conversion from a TAC bid formulation to a qd formulation is a safe and effective strategy for the management of stable LT patients.

Conversion From Twice-Daily to Once-Daily Tacrolimus in Stable Liver Transplant Patients: Effectiveness in a Real-World Setting

BackgroundThe prolonged-release once-daily (QD) tacrolimus is a formulation developed to improve adherence to immunosuppressant (IS) regimen, reducing the frequency of dosing, and to increase safety, avoiding toxic peak concentrations. We evaluated efficiency and quality of conversion from twice-daily (BID) to QD tacrolimus formulation in stable liver transplant (LT) recipients in the real-setting of a gastrohepatology team peripheral to LT centers. Patients and methodsThirty-four LT recipients (median age 60 years, range 33–69) were switched from BID tacrolimus to QD tacrolimus (1:1 dose) at a median of 38 months (range 8–211) after transplantation. Tacrolimus levels and laboratory analyses were recorded before and postconversion. Adherence to IS treatment was measured by a modified “Basel Assessment of Adherence Scale to Immunosuppressives.” ResultsMedian postconversion follow-up was 21 months (range 6–35, at least 12 months in 30 patients). Mean total tacrolimus daily dose and mean tacrolimus trough level were not significantly different before and after the switch (3.1 ± 2.3 preconversion versus 3.1 ± 2.5 and 3.0 ± 2.5 mg at 6 and 12 months postconversion, respectively; and 5.3 ± 1.8 preconversion versus 4.6 ± 1.4 and 4.5 ± 1.8 ng/mL at 6 and 12 months postconversion, respectively). All patients maintained stable liver and metabolic parameters. Renal function by glomerular filtration rate increased (67 ± 17 preconversion versus 73 ± 19 and 73 ± 20 mL/min at 6 and 12 months postconversion, respectively; P = .003). No acute rejection episode or major severe adverse events occurred postconversion. Patient-reported outcome showed a reduction of missed IS doses. ConclusionWe observed that in a real-world setting far from LT centers, the switch from BID tacrolimus to QD tacrolimus in stable LT recipients is efficient (safe and effective) to improve quality of medical care, with possibly better IS adherence and improvement of renal function.

Once– versus twice–daily tacrolimus: are the formulations equivalent?

Tacrolimus is one of the most often used immunosuppressive drugs in organ transplantation. It was first approved in 1994 for use in liver transplantation, replacing cyclosporine A, due to better absorption properties regardless of bile secretion. Then it use was extended to other organs and nowadays more that 90% of kidney graft recipient in the United States receive tacrolimus as a basic immunosuppressant [1]. The use of tacrolimus is complicated by its narrow therapeutic index and wide intra– and interpatient pharmacokinetics variability, thus it dosage should be based on monitoring trough drug blood concentration. The main complications of drug overdosage are nephro– and neurotoxicity and metabolic disturbances like posttransplant diabetes mellitus and hyperlipidemia. On the other hand low, non–therapeutic drug blood level can lead to graft rejection and loss. Patients’ noncompliance is the main cause of fluctuating tacrolimus blood concentration and in many cases could be the reason of acute graft rejection episodes. It is an important problem both in young, active but also in older kidney graft recipients and reduction of immunosuppressive drugs daily doses is one method to overcome this problem [2]. The once–daily (OD) extended–release formulation of tacrolimus (Advagraf, Astellas) was launched in 2007 in 0.5, 1, 3, and 5 mg doses. This drug formulation allows most of liver transplant and some kidney transplant recipients (on tacrolimus monotherapy or in dual therapy with prednisone) to use only one morning dose of immunosuppressants. Such therapy simplifies treatment protocol and increases patient compliance. Converting patients from twice daily (BID) to OD tacrolimus was proposed on equivalent daily dose but there was a concern of adequate blood levels after treatment switch. We observed in our center that OD tacrolimus doses had to be 10–15% higher than BID formulation to get the same trough blood drug concentration after conversion. In a multicenter, open–label, phase III study in stable adult liver transplant recipients converted from tacrolimus BID to OD (1:1 [mg:mg] total daily dose basis). Following conversion, mean tacrolimus trough levels were reduced by approximately 15% (7.5 ng/ml vs. 6.5 ng/ml; P <0.0001) but were more consistent, showing reduction between– and within–patient variability in trough levels [3]. However, in our retrospective analysis of 60 kidney graft recipients converted from tacrolimus BID to OD formulation in identical (1:1) daily doses in late posttransplant period trough blood drug concentration did not significantly differ pre and after conversion. OD tacrolimus doses were increased in 11 patients and decreased in 13 patients based on trough blood concentration during consecutive patient visits (unpublished data). OD tacrolimus is non inferior to BID formulation in long term effect in kidney transplant recipients. A systematic review of 6 randomized controlled trials and 15 observational studies revealed no significant differences in biopsy–proven acute rejection, patient and graft survival between the two formulations at 12 months [4]. However, there are some disadvantages of OD tacrolimus therapy. First, risk of overdose–related side effects is very high in first postransplant days and with BID tacrolimus formulation dose correction can be made with the evening dose. Secondly, only 1 mg OD tacrolimus capsules are reimbursed in Poland, making treatment rather difficult in case of higher daily doses. In the present paper authors describe their experience with kidney transplant recipients from living donors who received OD tacrolimus [5]. They investigated tacrolimus pharmacokinetics and compared the dose of OD tacrolimus OD TAC to BD drug formulation. The study group is relatively small and there are some demographic differences between the groups that could affect pharmacokinetic parameters of the study drug: patients on OD tacrolimus were younger and were shorter time on dialysis. The authors compare daily doses and minimal concentration (Cmin) of both formulations, what is most important in clinical practice. However, detailed pharmacokinetic parameters are presented only for OD tacrolimus. In conclusions OD tacrolimus appears to have efficacy and safety equivalent to that of BD formulation but a larger dose of OD tacrolimus compared to that of BD drug form may be required during the early period after kidney transplantation [5].

Long Term Results of Conversion from Twice-Daily Tacrolimus (Prograf®) to Once-Daily Prolonged Release Tacrolimus (Advagraf®) in Stable Liver Transplant Recipients: University of Bologna Experience

Long Term Results of Conversion from Twice-Daily Tacrolimus (Prograf®) to Once-Daily Prolonged Release Tacrolimus (Advagraf®) in Stable Liver Transplant Recipients: University of Bologna Experience

Conversion from Twice-Daily to Once-Daily Tacrolimus Administration in Liver Transplant Patient: Results of Long Term Follow-Up

The aim of this study was to assess the long term effects of once-daily tacrolimus (OD-TAC) in a cohort of stable liver recipients converted from the twice daily tacrolimus (TD TAC), with a particular attention on the possible effects on renal function.Between September 2008 and September 2010 conversion from TD-TAC to OD-TAC was proposed in adult stable liver transplant recipients who were followed as outpatients in our Transplant centre. Conversion from TC-TAC to OD-TAC was based on a 1 mg: 1 mg proportion. Tacrolimus through levels, laboratory parameters, metabolic disorders and any adverse events were evaluated at 1, 3, 6, 12 and 24 months after conversion. Renal function was evaluated using creatinine plasma levels and estimated glomerular filtration rate (GFR) derived from the Modification of Diet in Renal Disease (MDRD). Analysis of variance and t test for paired data were utilised for the comparison of the results obtained at the scheduled controls.Sixty-five patients were enrolled in the study (50 males, 15 females, mean age 59±8 years). Median time since liver transplant (LT) was 39 months (range: 6 to 83 months). All patients were followed for a minimum of 12 months. Ninety per cent of patients stabilized their blood levels within 45 days. Liver function, glucose and plasma lipids concentration and arterial blood pressure remained stable during the study. Renal function improved during the 24 months of follow-up. No adverse events or acute rejection episodes were recorded during the study.Considering the advantage on patient compliance, the equivalent efficacy and the adequate safety of OD-TAC formulation may represent a useful option in liver transplant patients, with a possible advantage on renal function.

Influence on MDR1 and CYP3A5 Polymorphisms on the Pharmacokinetic of Once Daily Formulation of Tacrolimus in Liver Transplant Patients

Introduction: Previous studies have shown that the efficacy and safety profile of a new modified-release, once-daily formulation of tacrolimus (TAC-XL) is similar to that of the immediate release formulation (TAC). Tacrolimus is metabolized by cytochrome P450 3A5 (CYP3A5) and is a substrate of the efflux transporter P-glycoprotein (PGP). The objective of this study was to investigate the influence of the genetic polymorphism of CYP3A5 and MDR1on the pharmacokinetics of TAC-XL after a switch from the immediate-release formulation of TAC. Methods: This prospective study was performed in 24 stable liver transplant recipients (16 males, 8 females). Blood levels were obtained prior to and 1 month after the switch to TAC-XL. Exposure variables (concentrations and area under the blood concentration-time curve from 0 to 24 hours [AUC]) were estimated using non- linear regression and Bayesian analysis. CYP3A5 (CYP3A5*1/*3 or *1/*1) and MDR1 (exon 26, C3435T, exon 21 G2677T) polymorphisms were assessed in post-transplant liver biopsies (donor tissue) and blood samples from transplant recipients. Results: median tacrolimus C0 levels measured were not significantly different after TAC or TAC-XL administration (6.1 ± 2.6 vs 6.4 ± 2.6 ng.ml-1, p=0.49). The correlation coefficient between observed and estimated tacrolimus levels after pharmacokinetic analysis of data was 0.92 Genotyping of MDR1 and CYP3A5 in blood samples of transplant patients showed 13 patients carrying MDR1 T allele and 4 patients with CYP3A5 *1 allele. MDR1 T allele carriers showed lower dose adjusted C0 levels and median AUC values although the differences were not statistically significant (CC vs T carriers: 2.8 ± 2.1 vs 1.1 ± 1.2 ng.ml-1.mg-1, p=0.08; 80.32 ± 98.4 vs 44.27 ± 52.4 ng. ml-1.h-1. mg-1, p=0.16). CYP3A5*1 allele carriers assessed in liver biopsies showed significant lower dose adjusted AUC median values in comparison with *3 allele carriers (n=7) (*1/*1 vs *3 carriers: 45.7 ± 7.3) vs 98.1 ± 93.9) ng. ml-1.h-1. mg-1, p< 0.05). Dose adjusted C0 median levels were also lower in the CYP3A5 expressor group analyzed in liver biopsies (*1/*1 vs *3 carriers: 1.12 ± 0.25) vs 3.1 ± 2.0) ng.ml-1.mg-1, p< 0.05) Conclusion: After switching from TAC to TAC-XL in stable liver transplant patients tacrolimus exposure significantly decreased in CYP3A5 liver expressors. Consequently, these patients should be carefully monitored and doses adjusted to reach the target AUC and Co levels. Further studies with a larger number of patients are needed to explore the impact of MDR1 genotype on tacrolimus bioavailability and blood levels.

Interleukin-9 in Stable Liver Transplant Recipients

IntroductionInterleukin-9 (IL-9) has recently been described to be involved in the maintenance of a tolerant environment, but there is no evidence of its role in human liver transplantation. The aim of our study was to measure the serum levels of IL-9 in stable liver transplant recipients and examine their influence on immunosuppressant load. MethodsSerum IL-9 levels were determined in 34 healthy subjects and 30 stable liver transplant recipients who were free of rejection episodes for at least 8 years. The results were analyzed according to the blood levels of calcineurin inhibitors (CNIs) at the time of the study: 13 patients showed high concentrations of either cyclosporine or tacrolimus (high CNI: cyclosporine > 80 ng/mL or tacrolimus > 5 ng/mL) and another 17 patients showed low CNI levels. ResultsThe concentrations of IL-9 were significantly higher among liver transplant recipients compared with healthy subjects. In addition, patients with low CNI blood levels showed higher serum levels of IL-9, an effect that was greater with tacrolimus, albeit not significantly. ConclusionsThese preliminary results indicated that increased serum IL-9 concentrations accompanied a lower immunosuppressive load. It remains to be established whether this relates to induction of tolerance in liver transplantation.

Pharmacodynamic monitoring by residual NFAT‐regulated gene expression in stable pediatric liver transplant recipients

Pharmacokinetic monitoring of CNI is unsatisfactory, because at comparable CNI blood concentrations frequency and severity of adverse effects vary considerably among individual patients. Determining the RGE of NFAT-regulated genes in leukocytes is a new pharmacodynamic approach to measure directly the functional consequences of calcineurin inhibition in T-lymphocytes. We compared clinical outcome parameters and RGE of activated T-cells after pLtx. We measured prospectively RGE of NFAT regulated genes in 33 pLTX recipients in the maintenance period after pLTX. CsA-treated patients with recurrent infections had significantly lower RGE rates (27%) than children without recurrent infections (50%; p = 0.04), whereas pharmacokinetic parameters of CsA and the concomitant immunosuppressive therapy were comparable between both groups. In patients on tacrolimus-based IS therapy NFAT RGE was only slightly reduced (90%). Pharmacodynamic monitoring of CsA by measurement of RGE in T-lymphocytes has the potential to identify over-immunosuppressed pediatric liver transplant recipients on a CsA-based IS therapy, while in children on low-dose tacrolimus therapy, RGE measurement does not provide additional clinically useful information.

Renal function, efficacy and safety postconversion from twice- to once-daily tacrolimus in stable liver recipients: an open-label multicenter study

This multicenter, open-label, phase III study assessed renal function, safety, and efficacy in stable adult liver transplant recipients converted from tacrolimus twice-daily (BID) to once-daily (QD). Patients received tacrolimus BID for 6weeks before conversion to tacrolimus QD (1:1 [mg:mg] total daily dose basis) for 12weeks. Primary endpoint: change in steady state creatinine clearance (CrCl) between treatment phases. Of 112 patients enrolled, 98 were converted to QD dosing (full analysis set [FAS]). Mean (SD) tacrolimus dose was 3.7 (1.7) mg/day during BID and at conversion, and 3.9 (1.8) mg/day at Week 12. 74.5% of patients required no dose adjustment on conversion (FAS). Mean tacrolimus whole blood trough levels were at the lower end of the recommended range during tacrolimus BID and QD; the difference between mean steady-state trough levels was statistically significant (7.5ng/ml vs. 6.5ng/ml; P<0.0001). Following conversion, mean tacrolimus trough levels were reduced by 15% (about 1ng/ml) without any cases of acute rejection, remained stable during the remainder of the study, and were more consistent, showing reduced between- and within-patient variability in trough levels. Renal function remained stable, demonstrating noninferiority of tacrolimus QD versus BID (relative difference in mean calculated CrCl -0.1% [±6.3%]). Patient and graft survival were 100%. Adverse events incidence was low during both treatment phases.

Impact of the Conversion of the Immunosuppressive Regimen from Prograf to Advagraf or to Sirolimus in Long-term Stable Liver Transplant Recipients: Indications, Safety, and Outcome

Background Compliance problems have arisen due to the twice a day administration of calcineurin inhibitors (CNI). We examined the safety, indications, and efficacy in terms of graft and patient survivals after conversion from tacrolimus to Sirolimus or Advagraf. Patients and Methods Between January 2006 and December 2009, 36 orthotopic liver transplantation patients underwent conversion of the immunosuppressive regimen from Prograf to either Sirolimus (group 1; n = 10) or Advagraf (group 2; n = 26). A group of patients taking Prograf was used as a control group (group 3; n = 15). We identified 51 patients of mean age 57 years and male:female percentages of 57%:43% from a prospective database. Renal and liver graft functions, patient survival, as well as laboratory and clinical data over at least 12 months (mean, 38) were the investigated parameters. Results Patients converted to Sirolimus did not show significantly improved renal function at 12 months as evidenced by creatinine levels (1.31 mg/dL +/− 0.47 vs 1.34 mg/dL +/− 0.78) and glomerular filtration rate (GFR, 57+/− 16 vs 56+/− 16 mL/min). However, there were significant antiproliferative effects. Patients with a hepatocellular carcinoma in the pretransplantation phase remained without a recurrence. The side effects including ankle edema, aphthae, and tachyarrhythmia absoluta, required reconversion to the CNI. Patients prescribed Advagraf reported a better life quality because of the single administration and a slight, insignificant improvement in renal function. An acute rejection episode was evidenced under either immunosuppresant. Conclusion Sirolimus is a safe immunosuppressive option in liver transplant recipients suffering from hepatocellular carcinoma. Advagraf showed a lower incidence of side effects than Prograf and probably is not as harmful for renal function, offering better compliance and better life quality.

Hot-topic debate on tolerance: Immunosuppression withdrawal

1. Liver allografts exhibit intrinsic tolerogenic properties that result in their spontaneous acceptance in many experimental animal models. 2. In clinical transplantation, liver allografts require milder immunosuppression regimens than other organs, are relatively resistant to antibody-mediated rejection, and only very rarely are lost because of immunological insults. 3. A fraction of stable liver transplant recipients can withdraw from all immunosuppression therapy and then maintain normal graft function and not experience rejection. This phenomenon is known as spontaneous operational tolerance (SOT). 4. The intentional discontinuation of immunosuppression in stable liver transplant recipients has led to successful weaning in almost 20% of recipients, but the true prevalence of SOT in unselected recipients is still unknown. 5. The prevalence could be higher in pediatric recipients undergoing transplantation before 1 year of age and in adult recipients with more than 10 years of posttransplant follow-up. 6. Rejection occurring during medically supervised immunosuppression weaning trials tends to be mild and, in the overwhelming majority of cases, can be easily resolved without the administration of high-dose immunosuppression. 7. Tolerant liver recipients exhibit specific transcriptional patterns in peripheral blood and liver tissue that may constitute future diagnostic markers of tolerance. 8. There is still no formal proof that the discontinuation of low-dose immunosuppression in long-term survivors of liver transplantation improves the morbidity and mortality rates associated with immunosuppression therapy.

Pharmacokinetics of tacrolimus converted from twice-daily formulation to once-daily formulation in Chinese stable liver transplant recipients

To evaluate the pharmacokinetics of tacrolimus in Chinese stable liver transplant recipients converted from immediate release (IR) tacrolimus-based immunosuppression to modified release (MR) tacrolimus-based immunosuppression. Open-label, multi-center study with a one-way conversion design was conducted. Eighty-three stable liver recipients (6-24 months post-transplant) with normal renal and stable hepatic function were converted from IR tacrolimus twice-daily treatment to MR tacrolimus once-daily treatment on a 1:1 (mg: mg) total daily dose basis. Twenty-four hour pharmacokinetic studies were carried out on d 0 (pre-conversion), d 1, and d 84 (post-conversion). The area under the blood concentration-time curve of MR tacrolimus from 0 to 24 h (AUC(0-24)) on d 1 was comparable to that of IR tacrolimus on d 0, with a 90% confidence interval (CI) for MR/IR tacrolimus of 92%-97%. The AUC(0-24) value for MR tacrolimus on d 84 with the daily dose increased by 14% was approximately 17% lower than that for IR tacrolimus. The 90% CI was 77%-90%, outside the bioequivalence range of 80%-125%. There was a good correlation between AUC(0-24) and concentration at 24 h (C(24)) for IR tacrolimus (d 0, r=0.930) and MR tacrolimus (d 1, r=0.936; d 84, r=0.903). The exposure to tacrolimus when administered MR tacrolimus once daily is not equivalent to that for IR tacrolimus twice daily after an 84-day conversion in Chinese stable liver transplant recipients. The dose should be adjusted on the basis of trough levels. The therapeutic drug monitoring for patients treated with IR tacrolimus is considered to be applicable to MR tacrolimus.

Cylex ImmuKnow assay in Chinese stable liver transplant recipients

Objective To identify the level of functional immunity as measured by the ImmuKnow assay in Chinese stable liver transplant recipients and to correlate these values with the dose and the trough levels of immunosuppressant, and with other clinical parameters of these patients. Methods Functional immune response was assessed by the ImmuKnow assay in 46 blood samples taken from 46 stable liver transplant recipients from Beijing Youan Hospital, Capital Medical University Liver Transplantation Center. Results The average ATP value in these stable liver transplant recipients was 203±114 ng/ml (range: 38.47 ATP ng/ml to 524.06 ATP ng/ml) at 22± 15 month post liver transplantation. There was no correlation either between ImmuKnow ATP values and the tacrolimus trough levels, or between ImmuKnow ATP values and the liver function (P<0. 05). Stepwise multiple regression analysis identified WBC and CD3+, CD3+ CD4+ as independent predictors of ImmuKnow assay levels when age, gender and underlying diagnosis were taken into account (P<0. 05). Five patients who were detected to have active HCV infection had lower ImmuKnow ATP values (<61 ng/ml). Conclusions The Cylex ImmuKnow assay ATP values were lower in Chinese stable liver transplant recipients compared with American patients. Further investigation is required to determine the role of the ImmuKnow assay in tailoring immunosuppressant therapy in liver transplant recipients. Key words: Liver transplant; The ImmuKnow assay; Immunosuppression

HLA-G Level on Monocytoid Dendritic Cells Correlates With Regulatory T-Cell Foxp3 Expression in Liver Transplant Tolerance

Human leukocyte antigen (HLA)-G is a nonclassical HLA class I molecule expressed as membrane-bound and soluble isoforms. Interaction of HLA-G with its receptor, immunoglobulin-like transcript 4 on dendritic cells (DCs) down-regulates their T-cell stimulatory ability. We examined expression of HLA-G, immunoglobulin-like transcript 4, other immune regulatory molecules (inducible costimulator ligand and glucocorticoid-induced tumor necrosis factor-related receptor ligand), and the activation marker CMRF44 on circulating monocytoid dendritic cell (mDC) and plasmacytoid dendritic cell by monoclonal antibody staining and flow cytometry. Three groups of stable liver transplant recipients: operationally tolerant (TOL), prospective immunosuppressive drug weaning, and maintenance immunosuppression (MI) were studied, together with healthy controls (HC). Serum HLA-G levels were measured by enzyme-linked immunosorbent assay. In TOL patients, monocytoid dendritic cell (mDC) but not plasmacytoid dendritic cell expressed higher HLA-G than in MI patients or HC. In TOL patients, the incidence of CD4(+)CD25(hi)CD127(-) regulatory T cells (Treg) and the intensity of Treg forkhead box p3 (Foxp3) expression were significantly higher than in the MI group. HLA-G expression on circulating mDC correlated significantly with that of Foxp3 in the TOL group. There was no correlation between immunosuppressive drug (tacrolimus) dose or trough level and HLA-G expression or Treg frequency or Foxp3 expression. The incidence of patients with circulating HLA-G levels more than 100 ng/mL was highest in the TOL group, although statistical significance was not achieved. Higher HLA-G expression on circulating mDC in TOL recipients compared with MI or HC, suggests a possible role of HLA-G in immune regulation possibly mediated by enhanced host Treg Foxp3 expression.

Finding the right time for weaning off immunosuppression in solid organ transplant recipients

Solid organ transplantation (SOT) requires lifelong immunosuppression (IS) to prevent rejection and graft loss. The currently adopted immunosuppressive protocols are numerous and are based on the administration of at least two molecules with diverse mechanisms of action. Owing to the fact that the majority of immunosuppressants act non-selectively, the immune system is normally oversuppressed, and as a result is less able to both defend the host against infection and to control the spread of malignant cells. Consequently, long-term IS is burdened by chronic toxicity, which may be highly invalidating and may significantly influence patient’s quality of life, compliance to treatment, overall success rate, and patient and graft survival. In an ideal scenario, SOT recipients should initially receive just enough IS to favor the onset of clinical operational tolerance (COT), a condition where the immune system of the host does not attack the graft in the absence of any immunosuppressant. COT has been documented after liver transplantation (LT) and renal transplantation (RT). First, COT was accidentally detected in patients who were nonadherent to treatment and who spontaneously decided to stop all IS without any medical guidance or surveillance. Later, it was described in recipients who required IS withdrawal following the occurrence of malignant diseases. Based on strikingly convincing experimental data, several tolerogenic protocols have recently been applied in patients but overall the results have been disappointing. The current literature demonstrates that COT can be safely achieved in stable LT recipients, with completely different strategies. Importantly, the onset of an episode of acute rejection during the attempt of IS withdrawal would not worsen the clinical outcome. On the contrary, COT remains a major challenge after RT because the onset of acute rejection will substantiate in graft loss. Currently, a major field of investigation aims to define markers of COT, which will allow the selection of individuals who are more prone to develop COT. Preliminary results in both RT and LT have just been announced; however, these markers will require validation in prospective studies.

Identification of operationally tolerant liver transplant recipients

KEY POINTS: (1) Liver allografts exhibit intrinsic tolerogenic properties that result in their spontaneous acceptance in many experimental animal models. (2) In clinical transplantation, liver allografts require milder immunosuppression (IS) regimens than other organs, are remarkably resistant to antibody-mediated rejection, and only very rarely are lost because of immunological insults. (3) A fraction of stable liver transplant recipients can withdraw from all IS therapy and then maintain normal graft function and not experience rejection. This phenomenon is known as spontaneous operational tolerance. (4) The intentional discontinuation of IS in stable liver transplant recipients has led to successful weaning in almost 20% of recipients, but the true prevalence of spontaneous operational tolerance in unselected recipients is still unknown. (5) The prevalence could be higher in pediatric recipients undergoing transplantation before 1 year of age and in adult recipients with more than 10 years of posttransplant follow-up. (6) Rejection occurring during medically supervised IS weaning trials tends to be mild and, in the overwhelming majority of cases, can be easily resolved without the administration of high-dose IS. (7) Tolerant liver recipients exhibit specific transcriptional patterns in peripheral blood and in liver tissue that may constitute future diagnostic markers of tolerance. (8) There is still no formal proof that the discontinuation of low-dose IS in long-term surviving liver recipients improves the morbidity and mortality rates associated with IS therapy. Liver Transpl 16:S82-S86, 2010. © 2010 AASLD.

Biomarkers of immunoregulatory status in stable liver transplant recipients undergoing weaning of immunosuppressive therapy

Biomarkers that reflect immune response recovery and predict clinical events during withdrawal or minimization of immunosuppressive therapy have not been evaluated. This study aimed to evaluate whether immune response recovers after withdrawal of long-term immunosuppressive treatment in stable liver transplant patients and to determine whether specific biomarkers reflect immune response reactivity and predict rejection. Pharmacokinetic–pharmacodynamic profiles were determined in 24 patients and 80 healthy donors before immunosuppressive treatment reduction began, at 50%, and at complete withdrawal. In patients who rejected, effector-T-cell response mediated by soluble IFN-γ, %CD4 +IFN-γ and %CD8 +IL-2/IFN-γ were significantly increased, while TGF-β1 production and the TGF-β1/IFN-γ ratio were significantly decreased. In patients with rejection, soluble IFN-γ and %CD8 +IL-2 were significantly higher before immunosuppressive treatment was reduced. Further studies are required, but this battery of biomarkers performed in whole blood could be a useful tool to monitor immunosuppressive treatment minimization or withdrawal protocols and identify patients at increased risk of rejection.

Role of tacrolimus prolonged release in the prevention of allograft rejection

Role of tacrolimus prolonged release in the prevention of allograft rejection Peter Abrams, Abhinav Humar, Henkie P TanDepartment of Surgery, Thomas E Starzl Transplantation Institute, University of Pittsburgh School of Medicine, Pennsylvania, USAAbstract: Successful management of the solid-organ transplant recipient begins with prevention of rejection and achieving a balance between insufficient and excessive immunosuppression. Standard tacrolimus therapy for prevention of solid-organ transplant rejection consists of 2 divided doses per day. In an effort to simplify tacrolimus dosing to once daily, a new formulation (tacrolimus prolonged release [PR]) was chosen for its combination of a similar extent of bioavailability and a substantially reduced rate of clearance. Several clinical conversion studies have now been completed using PR to clarify its pharmacokinetics, efficacy at prevention of allograft rejection, and safety profiles in solid-organ transplant patients. A cohort of 67 stable kidney transplant recipients was converted from standard tacrolimus to PR in an open-label, multicenter study in the United States and Canada. A second open-label, multicenter study was performed in liver transplant recipients with stable graft function on standard tacrolimus therapy converted to PR. A third conversion study was performed as an open-label study at 5 centers in the United States in stable pediatric liver transplant recipients. As medication noncompliance can significantly contribute to the incidence of graft rejection and graft loss in transplant recipients, a potentially significant advance in the transplant community&rsquo;s ongoing mission to optimize prevention of rejection occurred with the development of a once-daily tacrolimus PR. The results of these preliminary studies suggest that select solid-organ transplant recipients converted to PR can be safely maintained using the same monitoring and patient care techniques historically used for standard tacrolimus therapy.Keywords: immunosuppression, tacrolimus allograft, organ transplant, rejection