Conversion from twice-daily tacrolimus capsules to once-daily extended-release tacrolimus (LCPT): a phase 2 trial of stable renal transplant recipients

Early Use of Tacrolimus Extended-Release in a Pediatric Kidney Transplant Recipient

Tacrolimus extended-release pharmacokinetics and its once-daily formulation provide beneficial properties, and its use has been evaluated in the adult kidney transplant population. Here, we report a case of successful conversion from tacrolimus immediate-release capsules to tacrolimus extended-release tablets in a pediatric kidney transplant recipient.

Trough level from twice daily to once daily tacrolimus in early conversion kidney transplant recipients: a prospective study

Background Early conversion from twice-daily tacrolimus (TAC-BID) to once-daily tacrolimus (TAC-OD) provides a greater benefit of reducing under-exposure of TAC-OD during the first period after transplantation. Information regarding the conversion dose among Asian kidney transplant recipients is still limited. Objective This study aimed to compare the trough levels (C_min) of TAC-BID (Prograf^®) and TAC-OD (Advagraf^®). The values were obtained from early conversion intervention by 1:1 milligram per-milligram. Setting A university-based hospital. Method This study employed a single-center, open-label, prospective and single-armed design. Fifteen de novo standard risk kidney transplant recipients were enrolled. Fourteen days after transplantation, the C_min of TAC-BID (pre-conversion C_min) was determined. Subsequently, TAC-BID was converted to TAC-OD with a similar dose. The C_min of TAC-OD was first measured at a steady state (immediate post-conversion C_min) and compared. All enrolled patients received therapeutic monitoring at the first and second months. Main outcome measure Pre-conversion C_min of TAC-BID and immediate post-conversion C_min of TAC-OD. Results The immediate post-conversion C_min was found to be 23% lowered than the pre-conversion C_min. However, the C_min of TAC-OD was found to be similar to the pre-conversion C_min compared during the follow-up period. Renal function was found to be stable in all patients over 2 months. Conclusion Early conversion therapy was associated with a significantly lower immediate post-conversion C_min but comparable C_min throughout the follow-up period. The "one to one conversion ratio" from TAC-BID to TAC-OD could be performed among Asian de novo kidney transplant recipients at an early period after transplantation.

Clinical Evaluation of Modified Release and Immediate Release Tacrolimus Formulations

The science of drug delivery has evolved considerably and has led to the development of multiple sustained release formulations. Each of these formulations can present particular challenges in terms of clinical evaluation and necessitate careful study to identify their optimal use in practice. Tacrolimus is an immunosuppressive agent that is widely used in organ transplant recipients. However, it is poorly soluble, has an unpredictable pharmacokinetic profile subject to important genetic polymorphisms and drug-drug interactions, and has a narrow therapeutic index. For these reasons, it represents an agent that could benefit from modified release formulations to overcome these limitations. The objective of this review is to discuss the clinical evaluation of immediate and modified release tacrolimus formulations in renal transplant recipients. Clinical trials from early development of immediate release tacrolimus to formulation-specific post-marketing trials of modified release tacrolimus formulations are reviewed with an emphasis on key elements relating to trial design end endpoint assessment. Particular elements that can be addressed with formulation alterations, such as pharmacokinetics, pharmacogenomics, and toxicity and corresponding clinical evaluations are discussed. In addition, current knowledge gaps in the clinical evaluation of immediate and modified release tacrolimus formulations are discussed to highlight potential avenues for the future development of different tacrolimus formulations with outcomes relevant to the regulators, the transplant community, and to transplant recipients. This review shows that new formulations may alter tacrolimus bioavailability, alleviate certain adverse events while potentially enhancing patient convenience.

Conversion From Once-Daily Prolonged-Release Tacrolimus to Once-Daily Extended-Release Tacrolimus in Stable Liver Transplant Recipients

OBJECTIVES

After organ transplant, strategies to simplify the therapeutic regimen may improve adherence and prevent rejection and/or graft loss. The aim of the present study was to evaluate the safety of conversion from once-daily prolonged-release tacrolimus (Advagraf; Astellas Pharma Europe Limited, Middlesex, UK) to once-daily extended-release tacrolimus (Envarsus; Chiesi SAS, Nanterre, France) in stable adult liver transplant recipients.

MATERIALS AND METHODS

This observational study inclu-ded 44 liver transplant patients (median age of 59 y; 63.6% men; median delay after transplant of 72.5 mo). Conversion was based on a 1:0.70 proportion.

RESULTS

Mean dose of tacrolimus was 2.65 ± 1.24 mg/day before conversion and 2.09 ± 1.68 mg/day after conversion (P < .05), with ratio of 1:0.79. Mean serum tacrolimus trough level increased after conversion (4.92 ± 1.65 vs 5.60 ± 2.89 ng/mL; P < .05), with ratio of 1:1.14. Six months after conversion, mean dose of tacrolimus was 1.65 ± 0.93 mg/day (ratio of 1:0.62) and mean serum tacrolimus trough level was 4.82 ± 1.85 ng/mL, similar to the initial level before conversion. At the end of follow-up, 2 patients had returned to once-daily prolonged-release tacrolimus because of adverse effects (allergy, digestive trouble), which resolved thereafter. The mean cost of tacrolimus therapy was 5.54 ± 2.29 Euros/patient/day before conversion and 4.11 ± 2.32 Euros/patient/day after conversion (P < .05).

CONCLUSIONS

Conversion from prolonged-release to extended-release tacrolimus in stable liver transplant patients is safe and cost-effective; however, initially, dose adaptations and careful monitoring are required.

High Intrapatient Tacrolimus Variability Is Associated With Worse Outcomes in Renal Transplantation Using a Low-Dose Tacrolimus Immunosuppressive Regime

BACKGROUND

High intrapatient tacrolimus variability has been associated with worse clinical outcomes postrenal transplantation. Theoretically, tacrolimus levels consistently outside the target therapeutic window may result in allograft dysfunction as subtherapeutic tacrolimus levels predispose to episodes of acute rejection, whereas supratherapeutic levels may cause nephrotoxicity.

METHODS

We investigated the effect of tacrolimus variability in a "Symphony" style low-dose tacrolimus based regime, by collecting data from 432 patients over a 4-year period.Three hundred seventy-six patients were included, with a mean follow-up of 1495 days. Tacrolimus variability 6 to 12 months after renal transplantation was calculated, and outcomes were compared in low (n = 186) and high variability (n = 190) groups.

RESULTS

High variability patients were found to be at increased risk of rejection during the first posttransplant year (P = 0.0054) and to have reduced rejection-free survival (hazard ratio, 1.953; 95% confidence interval, 1.234-3.093; P = 0.0054). High variability patients had significantly worse (P < 0.0001) glomerular filtration rates at 1, 2, 3, and 4 years posttransplant. High variability patients were at increased risk of allograft loss (hazard ratio, 4.928; 95% confidence interval, 2.050-11.85; P = 0.0004).

CONCLUSIONS

This suggests that highly variable tacrolimus levels predict worse outcomes postrenal transplantation, although the causal nature of this relationship remains unclear. High tacrolimus variability may identify a subset of patients who warrant increased surveillance and patient education regarding dietary and medication compliance.

Emerging drugs for prevention of T-cell mediated rejection in liver and kidney transplantation

INTRODUCTION

Acute and chronic graft rejection continues to be an important problem after solid organ transplantation. With the introduction of potent immunosuppressive agents such as calcineurin inhibitors, the risk of rejection has been significantly reduced. However, the adverse effects of life-long immunosuppression remain a concern, and there exist a fine balance between over-immunosuppression and risk of rejection. Areas covered: In this review, the current standard of care in immunosuppressive therapy, including the use of steroids, calcineurin inhibitors, mycophenolate prodrugs and mammalian target of rapamycin inhibitors, will be discussed. Newer immunosuppressive agents showing promising early data after liver and kidney transplantation will also be explored. Expert Opinion: Currently, calcineurin inhibitors continue to be a vital component of immunosuppressive therapy after solid organ transplantation. Although minimization and avoidance strategies have been developed, the ultimate goal of inducing tolerance remains elusive. Newer emerging agents should have potent and specific immunosuppressive activity, with minimal associated side effects. An individualized approach should be adopted to tailor immunosuppression according to the different needs of recipients.

Influence of tacrolimus metabolism rate on renal function after solid organ transplantation

The calcineurin inhibitor (CNI) tacrolimus (TAC) is an integral part of the immunosuppressive regimen after solid organ transplantation. Although TAC is very effective in prevention of acute rejection episodes, its highly variable pharmacokinetic and narrow therapeutic window require frequent monitoring of drug levels and dose adjustments. TAC can cause CNI nephrotoxicity even at low blood trough levels (4-6 ng/mL). Thus, other factors besides the TAC trough level might contribute to CNI-related kidney injury. Unfortunately, TAC pharmacokinetic is determined by a whole bunch of parameters. However, for daily clinical routine a simple application strategy is needed. To address this problem, we and others have evaluated a simple calculation method in which the TAC blood trough concentration (C) is divided by the daily dose (D). Fast TAC metabolism (C/D ratio < 1.05) was identified as a potential risk factor for an inferior kidney function after transplantation. In this regard, we recently showed a strong association between fast TAC metabolism and CNI nephrotoxicity as well as BKV infection. Therefore, the TAC C/D ratio may assist transplant clinicians in a simple way to individualize the immunosuppressive regimen.

A Steady-State Head-to-Head Pharmacokinetic Comparison of All FK-506 (Tacrolimus) Formulations (ASTCOFF): An Open-Label, Prospective, Randomized, Two-Arm, Three-Period Crossover Study

This two-sequence, three-period crossover study is the first pharmacokinetic (PK) study to compare all three innovator formulations of tacrolimus (twice-daily immediate-release tacrolimus capsules [IR-Tac]; once-daily extended-release tacrolimus capsules [ER-Tac]; novel once-daily tacrolimus tablets [LCPT]). Stable renal transplant patients were dosed with each drug for 7 days, and blood samples were obtained over 24 h. Thirty subjects were included in the PK analysis set. A conversion factor of 1:1:0.80 for IR-Tac:ER-Tac:LCPT was used; no dose adjustments were permitted during the study. The median (interquartile range) total daily dose was 6.0 (4.0-8.0) mg for IR-Tac and ER-Tac and 4.8 (3.3-6.3) for LCPT. Significantly higher exposure on a per milligram basis, lower intraday fluctuation and prolonged time (Tmax ) to peak concentration (Cmax ) were found for LCPT versus IR-Tac or ER-Tac. ER-Tac showed no differences versus IR-Tac in exposure, Cmax , Tmax or fluctuation. The observed exposure of IR-Tac was used to normalize exposure for LCPT and ER-Tac, resulting in the following recommended total daily dose conversion rates: IR-Tac:ER-Tac, +8%; IR-Tac:LCPT, -30%; ER-Tac:LCPT, -36%. After exposure normalization, Cmax was ~17% lower for LCPT than for IR-Tac or ER-Tac; Cmin was ~6% lower for LCPT compared with IR-Tac and 3% higher compared with ER-Tac.

Meltdose Tacrolimus Pharmacokinetics

BACKGROUND

Nonadherence to immunosuppressive therapy contributes to the loss of grafts. One of the problem is the fractioning of immunosuppressive dose. In fact, it was demonstrated that a single daily dose (QD) is associated with an increased adherence to therapy compared with twice daily dosing (BID). Tacrolimus (TAC), calcineurin inhibitor, is one of immunosuppression pillar in organ transplantation and its action is strongly correlated with blood concentration and therefore the therapeutic drug monitoring is recommended in the guidelines. However, one of the critical points of TAC is the poor and variable bioavailability that influences immunosuppression, and is also responsible for adverse effects.

METHODS

MeltDose® Technology is a new technology to improve efficacy and/or reduce side effects. This new technology applied to TAC (Envarsus® or LCP-TAC) has achieved 4 main objectives: (1) improved bioavailability, (2) reduced dose fractioning to one tablet per day, (3) limited variability concentrations of TAC, and (4) lower doses of TAC will be administered.

RESULTS

We analyzed the pharmacokinetic profile, efficacy, and security of Envarsus®.

A preliminary study searching for the right dose of tacrolimus in very young (≤4 years) renal transplant patients

OBJECTIVES

The Radboudumc Amalia Children's hospital in the Netherlands has a programme for renal transplantation in children aged ≤4 years. Children receive chronic corticosteroid sparing immunosuppressive therapy that consists of tacrolimus and mycophenolate mofetil. This work aimed to describe the PK of tacrolimus in children ≤4 years with renal transplants.

METHODS

Paediatric renal transplant patients aged ≤4 years were included in this analysis. A PK curve of tacrolimus recorded ≤3 weeks after transplantation has been standard of care in our institution and aided in adjusting the dose in each patient to attain a target AUC_0-12h of 210 μg h/l early after transplantation.

KEY FINDINGS

Eight patients were included. The first two patients received an initial twice-daily regimen and the subsequent six patients a three-times daily regimen. Median dose-corrected AUC_tau was 63 μg h/l. AUC target attainment was 37.5%. Of the remaining patients, two had an AUC very close to (around 10% below) the target.

CONCLUSIONS

Large interindividual variability of tacrolimus was observed and showed suboptimal AUC target attainment. In this population, an even more aggressive approach of higher doses (e.g. 0.4 mg/kg per day) and more early AUC determination should be considered. This should be evaluated prospectively in a larger group of patients.

LCPT once-daily extended-release tacrolimus tablets versus twice-daily capsules: a pooled analysis of two phase 3 trials in important de novo and stable kidney transplant recipient subgroups

African-American and elderly kidney transplant recipients (KTR) have increased risk for poor clinical outcomes post-transplant. Management of immunosuppression may be challenging in these patients and contribute to worse outcomes. A novel once-daily formulation of tacrolimus (LCPT) has demonstrated noninferiority, similar safety, improved bioavailability, a consistent concentration time profile, and less peak and peak-trough fluctuations vs. tacrolimus twice-daily (Tac BID). This pooled analysis of two phase 3 randomized, controlled trials, including 861 (LCPT N = 428; Tac BID N = 433; 38% of patients were stable KTR, and 62% were de novo KTR) patients, examined the efficacy of LCPT in KTR subgroups (blacks, females, and age ≥65). Overall, treatment failure [death, graft failure, centrally read biopsy-proven acute rejection (BPAR), or lost to follow-up] at 12 months was as follows: LCPT: 11.9%, BID Tac: 13.4% [-1.48% (-5.95%, 2.99%)]. BPAR rates were as follows: LCPT: 8.2%, Tac BID: 9.5% [-1.29% (-5.14%, 2.55%)]. Numerically, fewer treatment failure events with LCPT were found in the majority of subgroups, with significantly less treatment failure associated with LCPT among black KTR [-13.82% (-27.22%, -0.31%)] and KTR ≥65 [-13.46% (-25.27%, -0.78%)]. This pooled analysis suggests numerically lower efficacy failure rates associated with LCPT among high-risk subgroups, in particular black KTR and KTR ≥65 years old.

Overview of extended release tacrolimus in solid organ transplantation

Tacrolimus (Prograf^©, Astellas Pharma Europe Ltd, Staines, United Kingdom; referred to as tacrolimus-BID) is an immunosuppressive agent to prevent and treat allograft rejection in kidney transplant recipients in combination with mycophenolate mofetil, corticosteroids, with or without basiliximab induction. The drug has also been studied in liver, heart and lung transplant; however, these are currently off-label indications. An extended release tacrolimus formulation (Advagraf^©, Astagraf XL^©) allows for once-daily dosing, with the potential to improve adherence. Extended release tacrolimus has similar absorption, distribution, metabolism and excretion to tacrolimus-BID. Phase I pharmacokinetic trials comparing extended release tacrolimus and tacrolimus-BID have demonstrated a decreased maximum concentration (C_max) and delayed time to maximum concentration (t_max) with the extended release formulation; however, AUC_0-24 was comparable between formulations. Overall extended release tacrolimus has a very similar safety and efficacy profile to tacrolimus-BID. It is not recommended in the use of liver transplant patient’s due to the increased risk of mortality in female recipients. There has been minimal data regarding the use of extended release tacrolimus in heart and lung transplant recipients. With the current data available for all organ groups the extended release tacrolimus should be dosed in a 1:1 fashion, the exception may be the cystic fibrosis population where their initial dose may need to be higher.

Genomics in CKD: Is This the Path Forward?

Recent advances in genomics and sequencing technology have led to a better understanding of genetic risk in CKD. Genetics could account in part for racial differences in treatment response for medications including antihypertensives and immunosuppressive medications due to its correlation with ancestry. However, there is still a substantial lag between generation of this knowledge and its adoption in routine clinical care. This review summarizes the recent advances in genomics and CKD, discusses potential reasons for its underutilization, and highlights potential avenues for application of genomic information to improve clinical care and outcomes in this particularly vulnerable population.

Tacrolimus for the prevention and treatment of rejection of solid organ transplants

Since its introduction to the antirejection armamentarium in 1994, tacrolimus has become the workhorse of transplant professionals for avoidance of solid organ transplant rejection. Not only does tacrolimus have potent immunosuppressive qualities that prevent rejection, but dosing is straight forward and it is generally well tolerated. However, in the long term, conditions such as calcineurin inhibitor nephrotoxicity can become a problem. A discussion of the compound, the pharmacokinetics, history, and current approved uses for tacrolimus is described. Indeed, tacrolimus is the most important drug for preventing transplant rejection. However, the increased appreciation for significant side effects, particularly in the long term, has led to building interest in new agents with different mechanisms of action and different metabolism.

Novel Once-Daily Extended-Release Tacrolimus Versus Twice-Daily Tacrolimus in De Novo Kidney Transplant Recipients: Two-Year Results of Phase 3, Double-Blind, Randomized Trial

BACKGROUND

1-year data from this trial showed the noninferiority of a novel once-daily extended-release tacrolimus (LCPT; Envarsus XR) to immediate-release tacrolimus (IR-Tac) twice daily after kidney transplantation.

STUDY DESIGN

Final 24-month analysis of a 2-armed, parallel-group, randomized, double-blind, double-dummy, multicenter, phase 3 trial.

SETTING & PARTICIPANTS

543 de novo kidney recipients randomly assigned to LCPT (n=268) or IR-Tac (n=275); 507 (93.4%) completed the 24-month study.

INTERVENTION

LCPT tablets once daily at 0.17 mg/kg/d or IR-Tac twice daily at 0.1 mg/kg/d; subsequent doses were adjusted to maintain target trough ranges (first 30 days, 6-11 ng/mL; thereafter, 4-11 ng/mL). The intervention was 24 months; the study was double blinded for the entirety.

OUTCOMES & MEASUREMENTS

Treatment failure (death, transplant failure, biopsy-proven acute rejection, or loss to follow up) within 24 months. Safety end points included adverse events, serious adverse events, new-onset diabetes, kidney function, opportunistic infections, and malignancies. Pharmacokinetic measures included total daily dose (TDD) of study drugs and tacrolimus trough levels.

RESULTS

24-month treatment failure was LCPT, 23.1%; IR-Tac, 27.3% (treatment difference, -4.14% [95% CI, -11.38% to +3.17%], well below the +10% noninferiority criterion defined for the primary 12-month end point). Subgroup analyses showed fewer treatment failures for LCPT versus IR-Tac among black, older, and female recipients. Safety was similar between groups. From month 1, TDD was lower for LCPT; the difference increased over time. At month 24, mean TDD for LCPT was 24% lower than for the IR-Tac group (P<0.001), but troughs were similar (means at 24 months: LCPT, 5.47 ± 0.17 ng/mL; IR-Tac, 5.8 ± 0.30 ng/mL; P=0.4).

LIMITATIONS

Trial participant eligibility criteria may limit the generalizability of results to the global population of de novo kidney transplant recipients.

CONCLUSIONS

Results suggest that once-daily LCPT in de novo kidney transplantation has comparable efficacy and safety profile to that of IR-Tac. Lower TDD reflects LCPT's improved bioavailability and absorption.

A single center, open-label, randomized pilot study to evaluate the safety and efficacy of tacrolimus modified release, Advagraf, versus tacrolimus twice daily, Prograf, in stable renal recipients (single)

BACKGROUND

Compliance with immunosuppressive regimens may affect clinical outcomes in renal transplant recipients. The aim of this study was to assess the safety and efficacy of standard-dose tacrolimus modified-release (TAC-MR) once daily versus tacrolimus (TAC) twice daily in stable renal transplant recipients.

METHODS

Ninety-nine stable renal transplant recipients were randomized to receive standard-dose tacrolimus twice daily or standard-dose modified-release tacrolimus once daily on a 1:1 (mg:mg) basis. The primary end point was the incidence of adverse events (AEs) in both groups. Secondary end points included biopsy-proven acute rejection, graft survival, patient survival, clinical indicators, and change in score of questionnaire.

RESULTS

The incidence of AEs was not different between the TAC and TAC-MR groups (56.0% vs 53.1%, P > .05). There were no significant differences in mean calculated glomerular filtration rate, blood pressure, glycosylated hemoglobulin (HbA1c), blood concentration of tacrolimus, and drug compliance. The scores of all items in the 36-item short form health survey (SF-36) were not different between groups, except for vitality. With respect to the subject questionnaire, there was no difference in question scores between the two treatment groups.

CONCLUSION

A regimen of TAC-MR once daily can be considered as an effective and safe alternative formulation of tacrolimus in stable renal transplant patients.

Switching STudy of Kidney TRansplant PAtients with Tremor to LCP-TacrO (STRATO): an open-label, multicenter, prospective phase 3b study

Tremor is a common side effect of tacrolimus correlated with peak-dose drug concentration. LCPT, a novel, once-daily, extended-release formulation of tacrolimus, has a reduced Cmax with comparable AUC exposure, requiring a ~30% dose reduction vs. immediate-release tacrolimus. In this phase 3b study, kidney transplant recipients (KTR) on a stable dose of tacrolimus and with a reported clinically significant tremor were offered a switch to LCPT. Tremor pre- and seven d post-conversion was evaluated by independent, blinded movement disorder neurologists using the Fahn-Tolosa-Marin (FTM) scale and by an accelerometry device; patients completed the QUEST (quality of life in essential tremor) and the Patient Global Impression of Change. There were 38 patients in the mITT population. A statistically and clinically significant improvement in tremor (FTM score, amplitude as measured by the accelerometry device and QOL [p-values < 0.05]) resulted post-conversion. Change in QUEST was significantly (p = 0.006) correlated (R = 0.44) with change in FTM; 78.9% of patients reported an improvement after switching to LCPT (p < 0.0005). To our knowledge this is the first trial in KTR that utilizes a sophisticated and reproducible measurement of tremor. Results suggest LCPT is associated with clinically meaningful improvement of hand tremor and may be an alternative management approach in lieu of further dose reduction of immediate-release tacrolimus for patients experiencing tremor.

Once-daily LCP-Tacro MeltDose tacrolimus for the prophylaxis of organ rejection in kidney and liver transplantations

Tacrolimus is a cornerstone of the immunosuppression regimen for prevention of allograft rejection in kidney and liver transplantations, with efficacy proven in many clinical trials. The currently available and extensively used tacrolimus formulations are flawed by large inter- and intra-individual variability, low bioavailability, wide peak-to-trough fluctuations and a narrow therapeutic index. Drug delivery technology can significantly impact the pharmacologic action of a drug, influencing its pharmacokinetic and subsequent therapeutic profile. LCP-Tacro is a novel, prolonged-release, MeltDose(®) formulation of tacrolimus designed for once-daily administration. A hallmark differentiation between this formulation and other once- and twice-daily tacrolimus products is the proprietary MeltDose drug delivery technology which is designed to improve the bioavailability of drugs with low water solubility. Considering the studies conducted to date, once-daily LCP-Tacro has shown improved pharmacokinetic properties, rapid achievement of therapeutic trough levels, consistent exposure, non-inferior efficacy and similar safety, with lower tacrolimus dose than other tacrolimus formulations.

Roles of the tacrolimus-dependent transcription factor IRF4 in acute rejection after liver transplantation

Acute rejection is a serious and life-threatening complication of liver transplantation (LTx). Tacrolimus (TAC) is a potent immunosuppressant used in experimental and clinical transplantation. Interferon regulatory factor 4 (IRF4) plays key roles as a transcription factor in the immune response. This study explored the role of IRF4 in acute rejection after LTx using TAC treatment. Here, LTx was performed in DA (RT1(n)) and Lewis (LEW) (RT1(l)) rats. The recipients were immunosuppressed with TAC (1.5mg/kg/day subcutaneously) or saline. Liver grafts were harvested 1, 3, 5, 7, and 10 days after LTx for histology, immunohistochemistry, western blotting and real-time PCR. Splenic mononuclear cells were activated with different doses of TAC. The nuclear factor of activated T cells (NFAT) signal pathway and CD4+ T subset-related transcription factors were assessed. The results showed that TAC treatment prolonged the survival of liver allografts in recipients, significantly attenuated hepatic tissue injury and improved liver function. IRF4 expression in grafts was down-regulated after TAC treatment. TAC inhibited the expression of IRF4, NFAT, Foxp3 and RORγt in splenic mononuclear cells in vitro. In conclusions, our studies showed that TAC attenuated acute rejection responses after LTx. This attenuation might depend on the TAC-NFAT-IRF4 signal pathway, which is crucial for the function of T helper subsets (Treg and Th17 cells) in acute rejection after LTx. These findings contribute to our understanding of the immune pharmacological mechanism of TAC to prevent rejection in LTx rats.

Recent trials in immunosuppression and their consequences for current therapy

PURPOSE OF REVIEW

Although the scarcity of clinical trials with de-novo immunosuppression has been typical over the last 2 years, several attempts have been made in drug conversion, dosing optimization, and bioequivalence. On the basis of recent clinical and animal studies, future directions of management and treatment are outlined.

RECENT FINDINGS

Studies with new tacrolimus formulations showed better bioavailability and lower doses, which might translate into less toxicity. The long-term results of studies with costimulation blockade confirmed their safety and efficacy. Calcineurin inhibitor (CNI)-free regimens based on mTOR inhibitors were shown to be associated with increased risk of the humoral response. Therefore, ongoing trials are predominantly designed to minimize calcineurin inhibitor dose only. Biologics, such as B-cell-specific agents (bortezomib and rituximab) and complement inhibitors (eculizumab) used to treat antibody-mediated rejection, recurrence of glomerulonephritis, are shifted to more preventive applications. The pretransplant quantification of alloreactive memory/effector T cell response may help to better stratify a patient's immunologic risk and allow for drug minimization.

SUMMARY

Despite clinical trials with innovative protocols with already established agents, tacrolimus-based and induction-based protocols have been shown to be the mainstay of immunosuppressive regimens. In the future, research aims to focus on biomarker-driven immunosuppression and cell therapy approaches.

Update on the clinical utility of once-daily tacrolimus in the management of transplantation

Adherence to immunosuppression and minimizing variability in drug exposure are important considerations in preventing rejection and maximizing overall transplant outcomes. The availability of once-daily tacrolimus may confer potential benefit by simplifying immunosuppressive regimens, thereby improving medication adherence among transplant recipients. Pharmacokinetic studies in healthy normal volunteers and stable transplant recipients suggest that once-daily tacrolimus is bioequivalent to twice-daily tacrolimus. Efficacy studies suggest that once-daily tacrolimus is noninferior to twice-daily tacrolimus with a concentration-dependent rejection risk. The incidence of biopsy-proven acute rejection, graft survival, and patient survival are more or less comparable between the two tacrolimus formulations. Once-daily tacrolimus has also been reported to have favorable effects on blood pressure, lipid profile, and glucose tolerance. Once-daily tacrolimus may be a viable option to consider for de novo immunosuppression or for conversion from conventional tacrolimus.

Conversion from twice daily tacrolimus capsules to once daily extended-release tacrolimus (LCP-Tacro): phase 2 trial of stable liver transplant recipients

LCP-Tacro is an extended-release formulation of tacrolimus designed for once-daily dosing. Studies in renal transplantation demonstrate greater bioavailability with similar safety and efficacy vs. twice-daily tacrolimus capsules. In this phase 2 study, adult stable liver transplant patients on tacrolimus capsules (Prograf) twice-daily were converted to tacrolimus tablets (LCP-Tacro) once-daily; patients continued on LCP-Tacro once-daily for days 8-21; target trough levels were 5-15 ng/mL; 24-hour pharmacokinetic (PK) assessments were done on days 7 (baseline pre-switch), 14, and 21. A 6 month extension study phase evaluated PK and safety following a total of 52 weeks of LCP-Tacro. Fifty-seven patients completed LCP-Tacro dosing in the core study; 43 completed the extension phase. The mean conversion ratio was 0.71 (Prograf:LCP-Tacro). PK data demonstrated consistent exposure (AUC) at the lower conversion dose. Cmax , Cmax /Cmin ratio, percent fluctuation and swing were significantly (P<0.001) lower and Tmax significantly (P<0.001) longer for LCP-Tacro vs. Prograf. AUC24 and Cmin correlation coefficients after 7 and 14 days of therapy were ≥0.93. There were no significant differences in PK parameters at week 26 vs. 14. One patient experienced an unrelated serious adverse event (SAE) during the core study and discontinued. There were six unrelated SAEs in the extension and 1 possibly related (rejection) that resolved; there were 3 discontinuations due to AEs during the extension. In this study, patients were safely converted from Prograf twice-daily to LCP-Tacro. The greater bioavailability of LCP-Tacro allowed for once-daily dosing and similar (AUC) exposure at a dose approximately 30% less than the total daily dose of Prograf. LCP-Tacro displayed significantly lower peak and peak-trough fluctuations. LCP-Tacro administered over one year was well tolerated with no new safety concerns.