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

Evaluation of Tacrolimus Concentrations and Clinical Outcomes Between Extended and Immediate Release Formulations in Kidney Transplant

Objectives: Tacrolimus remains the mainstay of immunosuppression in kidney transplantation. Understanding the relationship between therapeutic tacrolimus levels and outcomes of acute rejection, patient/graft survival, and tolerability are important. The relationship between time to therapeutic tacrolimus levels and outcomes has not been well established, specifically with the use of extended release tacrolimus formulation (LCP-Tac). This study investigated time to therapeutic tacrolimus levels of 2 tacrolimus formulations, LCP-Tac and immediate release tacrolimus (IR-Tac), as a predictor of clinical outcomes. Methods: This was a single-center, retrospective, cohort study of kidney transplant recipients at Duke Hospital between 2013-2021. The primary objective evaluated the difference in time to therapeutic tacrolimus levels with LCP-Tac vs IR-Tac regimens. Secondary endpoints included time within therapeutic range during the first 3 months post-transplant, incidence of biopsy-proven rejection, development of de novo donor specific antibodies, and patient and allograft survival at 12 months post-transplant. Results: 128 patients were included (63 in LCP-Tac group and 65 in IR-Tac group). The time to therapeutic tacrolimus level was similar between formulations (7.2 days with LCP-Tac compared to 6.7 days with IR-Tac, P = .63). The time within therapeutic range during the first 3 months post-transplant, via modified Rosendaal, was similar with LCP-Tac and IR-Tac (56.1% vs 64.8%, respectively). Rates of biopsy-proven acute rejection at 12 months were similar (7/63 (11.1%) compared to 4/65 (6.2%)). There was no difference in patient/graft survival between groups. Conclusions: The time to therapeutic tacrolimus levels did not differ based on tacrolimus formulation and was not correlated with clinical outcomes.

The estimation of healthcare cost of kidney transplantation in Japan using large-scale administrative databases

BACKGROUND

The financial burden of kidney replacement therapy (KRT) is considerable, and detailed information on KRT costs is essential for managing these huge healthcare costs. However, cost analyses for kidney transplantation (KTx) are limited in Japan. This study aimed to report the healthcare costs of KTx recipients in Japan based on large medical receipt data.

METHODS

This cost analysis of KTx recipients using the Japan Medical Data Center Claims Database between January 2005 and August 2020 identified living donor KTx (LDKT) and deceased donor KTx (DKT) recipients. The primary outcome was the total direct healthcare costs of KTx recipients. As an exploratory analysis, we examined the factors that contributed to the increase in the costs of LDKT.

RESULTS

In total, 84 LDKT and 17 DKT recipients were included in this study. The total healthcare costs for LDKT and DKT recipients during the first year after KTx were 6,639,982 and 6,840,450 JPY/year, respectively. However, after the second year post-KTx, total healthcare costs decreased to 1,735,931 and 1,348,642 JPY/year for LDKT and DKT recipients, respectively. During the first year, inpatient costs accounted for > 70% of the total healthcare costs, whereas pharmaceutical costs accounted for more than half after the second year post-KTx. The use of everolimus and male sex were associated with higher and lower total healthcare costs in the first and subsequent years after LDKT, respectively.

CONCLUSION

Using large-scale administrative databases, this study revealed the total healthcare costs of KTx in Japan and provided valuable information for the health technology assessment of KTx.

Effects of switching from twice-daily tacrolimus to once-daily extended-release meltdose tacrolimus on cellular immune response

Background

LCP-Tacro [LCPT], a novel once-daily, extended-release formulation of tacrolimus, has a reduced Cmax with comparable AUC exposure, requiring a ∼30% dose reduction in contrast to immediate-release tacrolimus (IR-Tac). Once-daily LCPT in de novo kidney transplantation has a comparable efficacy and safety profile to that of IR-Tac with advantages in bioavailability and absorption. The present investigation intends to analyze the effects of conversion from IR-Tac to LCPT on phenotype and function of T-cells and B-cells.

Methods

16 kidney transplant patients treated by triple standard immunosuppression with a stable graft function undergoing a switch from IR-Tac to LCPT were included in this observational prospective study. We measured the main immune cell types and performed an in-depth characterization of B cell, dendritic cells and T cells including regulatory T cells of the patients before, 4 and 8 weeks after IR-Tac to LCPT conversion using multi-parameter fl ow cytometry. Additionally, we analyzed T cells by assessing third-party antigens (Tetanus Diphtheria, TD)-reactive T cells, which could be analyzed by restimulation with tetanus vaccine.

Results

Overall, we found no significant alterations following LCPT conversion for the most immune cell populations with a few cell populations showing transient quantitative increase. Thus, 4 weeks after conversion, more regulatory T cells could be measured in the patients with a significant shift from memory to naïve Tregs. Furthermore, we found a transient B cell expansion 4 weeks after conversion from IR-Tac to LCPT. There were no changes in the percentage of other basic immune cell types and the antigen-reactive T cells were also not altered after changing the medication to LCP-tacrolimus.

Conclusion

Here, we demonstrate first insights into the immune system changes occurred under IR-Tac to LCPT conversion therapy in kidney transplant patients. While phenotypic and functional characteristics of the most immune cell populations did not change, we could observe an a transient expansion of regulatory T cells in peripheral blood following IR-Tac to LCTP conversion, which might additionally contribute to the overall immunosuppressive effect.

Immediate-Release versus Extended-Release Tacrolimus: Comparing Blood Pressure Control in Kidney Transplant Recipients - A Retrospective Cohort Study

BACKGROUND

Hypertension (HTN) is a common side effect of tacrolimus (Tac), the first-line antirejection medication for kidney transplant recipients. The impact of immediate-release tacrolimus (Tac IR) dosed twice daily versus extended-release tacrolimus (Tac ER) dosed once daily on long-term blood pressure control in kidney transplant recipients remains understudied. This study aims to compare the use of Tac IR versus Tac ER in kidney transplant recipients and evaluate the effects of the different formulations on systolic blood pressure (SBP), diastolic blood pressure (DBP), and HTN crisis.

METHODS

This retrospective cohort study at a single institution collected baseline characteristics, time-varying exposure to Tac IR versus Tac ER, SBP, DBP, HTN crisis, and confounders at each posttransplant visit. A marginal structural linear mixed-effects model was employed to analyze the longitudinal blood pressure control in kidney transplant recipients receiving Tac IR and Tac ER.

RESULTS

The final analysis included 654 patients, with mean ages of 52.0 years for Tac IR and 50.3 years for Tac ER. Males constituted 56.7% in Tac IR and 55.0% in Tac ER. Notably, the black population had 2.44 times higher odds of receiving Tac ER after adjusting for the rest of the baseline characteristics. No difference was found between longitudinal SBP (p = 0.386, 95% CI: -1.00, 2.57) or DBP (p = 0.797, 95% CI: -1.38, 1.06).

CONCLUSION

Our study indicates that posttransplant patients taking Tac ER exhibit no difference in chronic SBP and DBP controls compared to Tac IR.

Immunosuppressive drug combinations after kidney transplantation and post-transplant diabetes: A systematic review and meta-analysis

Post-transplant diabetes mellitus (PTDM) is a frequent complication after kidney transplantation (KT). This systematic review investigated the effect of different immunosuppressive regimens on the risk of PTDM. We performed a systematic literature search in MEDLINE and CENTRAL for randomized controlled trials (RCTs) that included KT recipients with any immunosuppression and reported PTDM outcomes up to 1 October 2023. The analysis included 125 RCTs. We found no differences in PTDM risk within induction therapies. In de novo KT, there was an increased risk of developing PTDM with tacrolimus versus cyclosporin (RR 1.71, 95%CI [1.38-2.11]). No differences were observed between tacrolimus+mammalian target of rapamycin inhibitor (mTORi) and tacrolimus+MMF/MPA, but there was a tendency towards a higher risk of PTDM in the cyclosporin+mTORi group (RR 1.42, 95%CI [0.99-2.04]). Conversion from cyclosporin to an mTORi increased PTDM risk (RR 1.89, 95%CI [1.18-3.03]). De novo belatacept compared with a calcineurin inhibitor resulted in 50% lower risk of PTDM (RR 0.50, 95%CI [0.32-0.79]). Steroid avoidance resulted in 31% lower PTDM risk (RR 0.69, 95%CI [0.57-0.83]), whereas steroid withdrawal resulted in no differences. Immunosuppression should be decided on an individual basis, carefully weighing the risk of future PTDM and rejection.

Impact of Switching From Immediate- or Prolonged-Release to Once-Daily Extended-Release Tacrolimus (LCPT) on Tremor in Stable Kidney Transplant Recipients: The Observational ELIT Study

Once-daily extended-release tacrolimus (LCPT) exhibits increased bioavailability versus immediate-release (IR-TAC) and prolonged release (PR-TAC) tacrolimus. Improvements in tremor were previously reported in a limited number of kidney transplant patients who switched to LCPT. We conducted a non-interventional, non-randomized, uncontrolled, longitudinal, prospective, multicenter study to assess the impact of switching to LCPT on tremor and quality of life (QoL) in a larger population of stable kidney transplant patients. The primary endpoint was change in The Essential Tremor Rating Assessment Scale (TETRAS) score; secondary endpoints included 12-item Short Form Survey (SF-12) scores, tacrolimus trough concentrations, neurologic symptoms, and safety assessments. Subgroup analyses were conducted to assess change in TETRAS score and tacrolimus trough concentration/dose (C0/D) ratio by prior tacrolimus formulation and tacrolimus metabolizer status. Among 221 patients, the mean decrease of TETRAS score after switch to LCPT was statistically significant (p < 0.0001 vs. baseline). There was no statistically significant difference in change in TETRAS score after switch to LCPT between patients who had received IR-TAC and those who had received PR-TAC before switch, or between fast and slow metabolizers of tacrolimus. The overall increase of C0/D ratio post-switch to LCPT was statistically significant (p < 0.0001) and from baseline to either M1 or M3 (both p < 0.0001) in the mITT population and in all subgroups. In the fast metabolizers group, the C0/D ratio crossed over the threshold of 1.05 ng/mL/mg after the switch to LCPT. Other neurologic symptoms tended to improve, and the SF-12 mental component summary score improved significantly. No new safety concerns were evident. In this observational study, all patients had a significant improvement of tremor, QoL and C0/D ratio post-switch to LCPT irrespective of the previous tacrolimus formulation administered (IR-TAC or PR-TAC) and irrespective from their metabolism status (fast or slow metabolizers).

Pharmacokinetics of Envarsus in pediatric kidney transplant recipients - phase 1 pilot conversion study

INTRODUCTION

Tacrolimus is the standard immunosuppressant for pediatric kidney transplants and is routinely administered twice daily (BD-tac). Envarsus (LCP-tac), an extended-release formulation, is approved for adults but not for pediatric patients.

METHODS

We conducted a pilot open-label phase 1 study in stable pediatric kidney transplant recipients (age < 18 at the time of study). Our primary objective was to compare the pharmacokinetics (Pk) of LCP-tac versus BD-tac. We conducted two 24-h Pk studies: pre-conversion (BD-tac) and 4 weeks post-conversion to LCP-tac. Patients were followed for 6 months, with the option to continue LCP-tac.

RESULTS

Five patients completed the study, with no returns to BD-tac. Median age was 15 years (range 11-17). LCP-tac exhibited an extended-release profile versus the bimodal profile of BD-tac. Time to maximum concentration was delayed (5 h vs. 1 h), and maximum concentration was lower (9.9 ng/mL vs. 14.4 ng/mL). Tacrolimus area under the curve (24 h) was comparable (141 ± 46.5 ng/mL vs. 164 ± 27.8 ng/mL). No new safety concerns arose. There were no rejection and no difference in eGFR at the study's end (1.5 mL/min/1.73 m2 , range - 1.7 to 2.3 mL/min/1.73 m2 ). Concentration/dose ratio was higher in LCP-tac (1.8 ± 0.64 vs. 0.8 ± 0.39). The final conversion ratio was 0.6 (BD-tac: LCP-tac).

CONCLUSION

Our pilot study confirms the extended-release Pk profile and improved absorption of LCP-tac compared to BD-tac. A larger study is needed to further evaluate the population Pk characteristics in children.

Early outcomes associated with de novo once-daily extended-release versus twice-daily immediate-release tacrolimus in a predominantly African American kidney transplant population: A single-center observational study

INTRODUCTION

The purpose of this study was to compare early outcomes of de novo LCPT (once-daily extended-release tacrolimus) to IR TAC (twice-daily immediate-release tacrolimus) in a predominantly African American (AA) adult kidney transplant population.

METHODS

This is a single center, retrospective cohort study. Patients were divided into two cohorts: IR TAC (administered between January 1, 2017, and January 31, 2019) and LCPT (administered between February 1, 2019, and May 31, 2020). Primary endpoints were changes in tacrolimus trough levels (ng/mL) and estimated glomerular filtration rate up to 12 months post-transplantation. Clinical endpoints included graft survival, delayed graft function, biopsy-proven rejection, CMV viremia, and BK. A propensity score weighted generalized linear mixed effects model was used for analysis.

RESULTS

The rate of change in tacrolimus levels was significantly higher in the LCPT cohort compared to the IR TAC cohort at 14 days post-discharge (.2455 ng/mL per day vs. .1073 ng/mL, respectively; p < .001). Subsequently, the LCPT cohort had a slightly higher rate of decline (-.015 ng/mL per day vs. -.010 ng/mL with IR TAC; p = .0894) up to 12 months post-discharge. Although eGFR was similar between the two cohorts at 12 months post-transplant, the rate of increase was slower in the LCPT cohort (.1371 mL/min per day vs. .1852 mL/min per day, p = .0314). No significant differences were found in graft survival, DGF, BPAR, CMV, or BK infection.

CONCLUSION

This study demonstrates that despite higher early trough levels with immediate post-transplant LCPT use, clinical outcomes are comparable to IR TAC at one-year post-transplant. Notably, LCPT use does not increase the incidence of DGF and that this formulation of CNI can be used as first line therapy post-transplant.

A multi-center interventional study to assess pharmacokinetics, effectiveness, and tolerability of prolonged-release tacrolimus after pediatric kidney transplantation: study protocol for a prospective, open-label, randomized, two-phase, two-sequence, single dose, crossover, phase III b trial

Background

Tacrolimus, a calcineurin inhibitor (CNI), is currently the first-line immunosuppressive agent in kidney transplantation. The therapeutic index of tacrolimus is narrow due to due to the substantial impact of minor variations in drug concentration or exposure on clinical outcomes (i.e., nephrotoxicity), and it has a highly variable intra- and inter-individual bioavailability. Non-adherence to immunosuppressants is associated with rejection after kidney transplantation, which is the main cause of long-term graft loss. Once-daily formulations have been shown to significantly improve adherence compared to twice-daily dosing. Envarsus®, the once-daily prolonged-release formulation of tacrolimus, offers the same therapeutic efficacy as the conventional twice-daily immediate-release tacrolimus formulation (Prograf®) with improved bioavailability, a more consistent pharmacokinetic profile, and a reduced peak to trough, which may reduce CNI-related toxicity. Envarsus® has been approved as an immunosuppressive therapy in adults following kidney or liver transplantation but has not yet been approved in children. The objective of this study is to evaluate the pharmacokinetic profile, efficacy, and tolerability of Envarsus® in children and adolescents aged ≥ 8 and ≤ 18 years to assess its potential role as an additional option for immunosuppressive therapy in children after kidney transplantation.

Methods/design

The study is designed as a randomized, prospective crossover trial. Each patient undergoes two treatment sequences: sequence 1 includes 4 weeks of Envarsus® and sequence 2 includes 4 weeks of Prograf®. Patients are randomized to either group A (sequence 1, followed by sequence 2) or group B (sequence 2, followed by sequence 1). The primary objective is to assess equivalency between total exposure (of tacrolimus area under the curve concentration (AUC0-24)), immediate-release tacrolimus (Prograf®) therapy, and prolonged-release tacrolimus (Envarsus®) using a daily dose conversion factor of 0.7 for prolonged- versus immediate-release tacrolimus. Secondary objectives are the assessment of pharmacodynamics, pharmacogenetics, adherence, gut microbiome analyses, adverse events (including tacrolimus toxicity and biopsy-proven rejections), biopsy-proven rejections, difference in estimated glomerular filtration rate (eGFR), and occurrence of donor-specific antibodies (DSAs).

Discussion

This study will test the hypothesis that once-daily prolonged-release tacrolimus (Envarsus®) is bioequivalent to twice-daily intermediate-release tacrolimus after pediatric kidney transplantation and may reduce toxicity and facilitate medication adherence. This novel concept may optimize immunosuppressive therapy for more stable graft function and increased graft survival by avoiding T-cell mediated and/or antibody-mediated rejection due to improved adherence. In addition, the study will provide data on the pharmacodynamics and pharmacogenetics of prolonged-release tacrolimus in children and adolescents.

Clinical Trial Registration

EUDRA-CT 2019-003710-13 and ClinicalTrial.gov, identifier NCT06057545.

Extended-release tacrolimus dosing and outcomes in pediatric and young adult transplant recipients - A single-center experience

BACKGROUND

Published data on LCP-tacrolimus (LCPT) in the pediatric population are limited.

METHODS

This single-center, retrospective, observational study describes LCPT doses needed to reach therapeutic ranges in pediatric and young adult kidney and liver transplant recipients in both de novo usage and conversion from immediate-release tacrolimus (IR-Tac). Adverse outcomes up to 12 months after LCPT initiation were also evaluated.

RESULTS

Forty-one transplant recipients (30 kidney, 11 liver) were included. The median initial doses of LCPT were 0.034 mg/kg (IQR 0.019) de novo and 0.09 mg/kg (IQR = 0.076) converted. The median doses at first therapeutic level were 0.086 mg/kg (IQR 0.028) de novo and 0.1 mg/kg (IQR 0.066) converted. The median LCPT:IR-Tac conversion ratio initially was 0.7 and 0.75 at therapeutic levels. The rate of AKI per 100 days of exposure to IR-Tac was 0.546 and 0.439 on LCPT. The percentage of patients with rejection was not different before and after conversion (clinical rejection 8.6% [n = 3] vs 11.4% [n = 4], p = .6; biopsy-proven rejection 2.9% [n = 1] vs 11.4% [n = 4], p = .11). One patient had graft loss unrelated to rejection, and the graft was explanted.

CONCLUSION

In this study, pediatric and young adult abdominal transplant recipients had therapeutic tacrolimus levels at LCPT doses below the adult-labeled dose; the conversion ratio from IR-Tac to LCPT at therapeutic level was similar. There were no identified safety concerns in de novo or converted LCPT use in pediatric and young adult patients.

A report of a prospective randomized trial of extended-release tacrolimus versus immediate release tacrolimus after liver transplantation with anti-thymocyte induction in a steroid free protocol

PURPOSE

Our study hypothesis was that once daily dosing of extended-release tacrolimus (XRT) would be a safe and effective immunosuppression (IS) with the potential to decrease adverse events (AEs) associated with immediate release tacrolimus (IRT) after liver transplantation (LT).

METHODS

All patients receiving LT at our center received rabbit anti-thymocyte globulin (RATG) induction therapy. Eligible patients were randomized in a 1:1 fashion to receive either XRT or IRT. Antimicrobial prophylaxis was the same between arms, and both groups received an antimetabolite for the first 6 months following LT. Patients were then followed at pre-determined study intervals for the following year after LT. We administered the RAND-36SF survey to assess patient's health-related quality of life at pre-determined intervals. All analysis was performed with an intention to treat basis.

RESULTS

We screened 194 consecutive patients and enrolled 110. Our control and study arms were well matched. Transplant characteristics were similar between groups. At all timepoints, both arms had similar serum creatinine and estimated glomerular filtration rate (eGFR), calculated by MDRD6 equation, with post-transplant GFRs between 60 and 70 mL/min/1.73 m2 . Tacrolimus trough levels were similar between arms. The XRT arm had fewer AEs (166) and fewer serious AEs (70) compared to IRT (201 and 99, respectively). AEs most commonly were renal, infectious, or gastrointestinal in nature. While not statistically significant, XRT was held temporarily (25 vs. 35 cases) or discontinued (3 vs. 11 cases) less frequently than IRT and had fewer instances of rejection (7 vs. 12 cases).

CONCLUSION

This analysis showed that XRT is safe and effective as de novo maintenance IS in a steroid-free protocol with RATG.

The association between tacrolimus exposure and tremor, headache and insomnia in adult kidney transplant recipients: A systematic review

PURPOSE

Tremor, headache and insomnia have been linked to the immunosuppressant, tacrolimus. The aim of this systematic review was to determine if there is a correlation between tacrolimus exposure and new-onset tremor, headache and insomnia experienced by adult kidney transplant recipients.

METHODS

PubMed, Embase, Cochrane Library and CINAHL databases were searched up to 11 April 2023 for published studies which reported on tacrolimus exposure in adult kidney transplant recipients, alongside information on treatment-emergent neurologic manifestations, including tremor, headache and insomnia. Review articles, case studies, conference abstracts and articles not published in English in peer-reviewed journals were excluded. The Physiotherapy Evidence Database and Newcastle-Ottawa Quality Assessment Scales were used to assess risk of bias. Extracted data was analysed via a narrative synthesis.

RESULTS

Eighteen studies involving 4030 patients in total were included in the final analysis. These comprised five randomised control trials and thirteen observational studies. Studies failed to find significant association between tacrolimus trough concentrations in whole blood and the incidence of neurologic side effects such as tremor, headache and insomnia; however, in one study the incidence of toxicity requiring a dose reduction increased with increasing, supratherapeutic targeted levels. Females, especially Black females, and older age were positively associated with the prevalence of neurologic adverse effects. Results were conflicting regarding whether extended-release formulations were associated with fewer neurologic complications than immediate-release formulations.

CONCLUSION

The varied study designs and criteria for reporting tremor, headache and insomnia impacted on the quality of the data for exploring the relationship between tacrolimus exposure and the onset of neurologic manifestations experienced after kidney transplantation. Studies that examine defined neurologic complications as the primary outcome, and that consider novel markers of tacrolimus exposure while assessing the potential contribution of multiple covariate factors, are required.

Dosing strategies for de novo once-daily extended release tacrolimus in kidney transplant recipients based on CYP3A5 genotype

BACKGROUND

Tacrolimus extended-release tablets have been Food and Drug Administration-approved for use in the de novo kidney transplant population. Dosing requi rements often vary for tacrolimus based on several factors including variation in metabolism based on CYP3A5 expression. Patients who express CYP3A5 often require higher dosing of immediate-release tacrolimus, but this has not been established for tacrolimus extended-release tablets in the de novo setting.

AIM

To obtain target trough concentrations of extended-release tacrolimus in de novo kidney transplant recipients according to CYP3A5 genotype.

METHODS

Single-arm, prospective, single-center, open-label, observational study (ClinicalTrials.gov: NCT037 13645). Life cycle pharma tacrolimus (LCPT) orally once daily at a starting dose of 0.13 mg/kg/day based on actual body weight. If weight is more than 120% of ideal body weight, an adjusted body weight was used. LCPT dose was adjusted to maintain tacrolimus trough concentrations of 8-10 ng/mL. Pharmacogenetic analysis of CYP3A5 genotype was performed at study conclusion.

RESULTS

Mean time to therapeutic tacrolimus trough concentration was longer in CYP3A5 intermediate and extensive metabolizers vs CYP3A5 non-expressers (6 d vs 13.5 d vs 4.5 d; P = 0.025). Mean tacrolimus doses and weight-based doses to achieve therapeutic concentration were higher in CYP3A5 intermediate and extensive metabolizers vs CYP3A5 non-expressers (16 mg vs 16 mg vs 12 mg; P = 0.010) (0.20 mg/kg vs 0.19 mg/kg vs 0.13 mg/kg; P = 0.018). CYP3A5 extensive metabolizers experienced lower mean tacrolimus trough concentrations throughout the study period compared to CYP3A5 intermediate metabolizers and non-expressers (7.98 ng/mL vs 9.18 ng/mL vs 10.78 ng/mL; P = 0 0.008). No differences were identified with regards to kidney graft function at 30-d post-transplant. Serious adverse events were reported for 13 (36%) patients.

CONCLUSION

Expression of CYP3A5 leads to higher starting doses and incremental dosage titration of extended-release tacro limus to achieve target trough concentrations. We suggest a higher starting dose of 0.2 mg/kg/d for CYP3A5 expressers.

Drug-drug interaction between paxlovid and tacrolimus in a patient with myasthenia gravis and SARS-CoV-2 infection

Patients with both myasthenia gravis (MG) and SARS-CoV-2 infection face treatment challenges due to potential drug interactions. One common immunosuppressant for MG, Tacrolimus, is primarily metabolized by the cytochrome P450. However, Paxlovid, an antiviral medication, inhibits cytochrome P450 activity, which can lead to increased Tacrolimus levels and potential toxicity when the two drugs are combined. In this case report, we present the case of a 39-year-old woman with early-onset MG who was initially treated with Tacrolimus. Later, she received Paxlovid for SARS-CoV-2 infection, which resulted in a sudden spike in Tacrolimus levels due to the drug interaction. This case emphasizes the importance of personalized treatment plans and close monitoring of drug interactions in patients with multiple health conditions. Clinicians should exercise vigilance regarding potential Tacrolimus interactions and regularly monitor blood levels to prevent adverse effects. Caution and close monitoring of Tacrolimus levels are essential when administering Paxlovid to patients on Tacrolimus therapy.

Comparison of a novel tablet formulation of tacrolimus and conventional capsule formulation in de novo kidney transplant recipients: a systematic review and meta-analysis

Background: The work aimed to compare the pharmacokinetic (PK) profiles and other outcomes reported in observational studies in de novo kidney transplant recipients (KTRs) receiving novel once-daily extended-release tablet tacrolimus (LCPT; LCP-tacrolimus; Envarsus XR) or receiving standard-of-care capsule tacrolimus (PR-Tac; prolonged-release tacrolimus; Advagraf/IR-Tac; immediate-release tacrolimus; Prograf). Methods: A systematic review was conducted for all randomized controlled trials (RCTs) and cohort studies investigating the outcomes in KTRs receiving LCPT or PR-Tac/IR-Tac. We systematically searched PubMed, Web of Science, and EMBASE, with no language restriction. The registered trials and references listed in relevant studies were also searched. Data were extracted for the PK profile, tacrolimus trough level (TTL), and changes in the estimated glomerular filtration rate (eGFR) and serum creatinine (Scr), biopsy-proven acute rejection (BPAR) rate, delayed graft function (DGF) rate, post-transplant diabetes mellitus (PTDM) rate, tremor rate (TR), death rate (DR), and rate of infection by cytomegalovirus (CMV). This study was registered with PROSPERO (registration number: CRD42023403787). Results: A total of seven eligible articles including 1,428 patients with 712 in the LCPT group versus 716 in the PR-Tac/IR-Tac group were included in this study for evidence synthesis. The baseline characteristics of the LCPT, PR-Tac, and IR-Tac groups were similar. The pooled analysis showed a higher PK profile in the LCPT group, and this result was consistent with those of all the included studies. In addition, no significant difference was observed for other outcomes. Conclusion: Considering heterogeneity between studies and potential bias, care providers should select agents based on patient-specific factors and their clinical experience for the immunosuppressive treatment of de novo KTRs.

Tremor Induced by Cyclosporine, Tacrolimus, Sirolimus, or Everolimus: A Review of the Literature

Calcineurin inhibitors such as cyclosporine and tacrolimus are immunosuppressant drugs that are known to induce tremors. Non-calcineurin inhibitors such as sirolimus and everolimus have also reportedly been accompanied by tremors, albeit less likely. However, the prevalence rates reported in the literature are notably wide, and the risk profiles for these drug-induced tremors are less understood. We searched PubMed to extract data on the risk of tremors with these drugs when prescribed for various transplant and non-transplant indications. We ascertained whether the risk of drug-induced tremor is influenced by the underlying diagnosis, dosing formulations, drug concentrations, and blood monitoring. We extracted data on treatment strategies and outcomes for tremors. Articles were primarily screened based on English language publications, abstracts, and studies with n ≥ 5, which included case series, retrospective studies, case-controlled studies, and prospective studies. We found 81 eligible studies comprising 33 cyclosporine, 43 tacrolimus, 6 sirolimus, and 1 everolimus that discussed tremor as an adverse event. In the pooled analysis of studies with n > 100, the incidence of tremor was 17% with cyclosporine, 21.5% with tacrolimus, and 7.8% with sirolimus and everolimus together. Regarding the underlying diagnosis, tremor was more frequently reported in kidney transplant (cyclosporine 28%, tacrolimus 30.1%) and bone marrow transplant (cyclosporine 40%, tacrolimus 41.9%) patients compared with liver transplant (cyclosporine 9%, tacrolimus 11.5%) and nontransplant indications (cyclosporine 21.5%, tacrolimus 11.3%). Most studies did not report whether the risk of tremors correlated with drug concentrations in the blood. The prevalence of tremors when using the twice-daily formulation of tacrolimus was nearly the same as the once-daily formulation (17% vs 18%). Data on individual-level risk factors for tremors were lacking. Except for three studies that found some benefit to maintaining magnesium levels, there were minimal data on treatments and outcomes. A large body of data supports a substantive and wide prevalence of tremor resulting from tacrolimus use followed by cyclosporine, especially in patients receiving a kidney transplant. However, there is little reporting on the patient-related risk factors for tremor, risk relationship with drug concentrations, treatment strategies, and outcomes.

Retrospective evaluation of LCP-tacrolimus (Envarsus XR) dosing in de novo kidney transplant

INTRODUCTION

Tacrolimus is known to exhibit significant inter- and intra-patient pharmacokinetic (PK) and pharmacodynamic (PD) variability regarding therapeutic response. LCP-tacrolimus (LCPT-Envarsus XR) was approved in 2018 for use as a de novo immunosuppressive agent in kidney transplants, but there is limited evidence to guide de novo dosing of LCPT in patients with obesity. The primary objective of this study was to evaluate the impact of different calculated weight-based de novo LCPT dosing on early transplant outcomes.

METHODS

This was a retrospective study of patients with obesity (BMI ≥ 30 kg/m2 ) who received a kidney transplant at the University of Illinois Hospital and Health System (UIH), between March 2019 and March 2021. Subjects were included if were age 18 years or older and received de novo LCPT throughout index hospitalization. The primary endpoint of this study was to compare correlations between the first tacrolimus trough level and dosing weight strategy (e.g., TBW, AdjBW, IBW).

RESULTS

There was a statistically significant, though modest, correlation between all three dosing strategies and the first tacrolimus trough level (TBW correlation coefficient = .431, p < .001; AdjBW correlation coefficient = .455, p < .001; IBW correlation coefficient = .465; p < .001). In regression modeling for supratherapeutic levels each additional .01 mg/kg increase in dose by TBW, AdjBW, and IBW increased the odds of a supratherapeutic level by 1.46, 1.34, and 1.24, respectively (p < .001).

CONCLUSIONS

The use of LCPT in kidney transplant recipients with obesity dosed using TBW demonstrated the strongest correlation with initial supratherapeutic tacrolimus levels. Larger prospective studies are needed to investigate the further impact of body weight on dosing regimens in the obese population.

Efficacy and safety of once-daily prolonged-release tacrolimus versus twice-daily tacrolimus in kidney transplant recipients: A meta-analysis and trial sequential analysis

BACKGROUND

Kidney transplantation is the most important treatment for end-stage renal disease. Immunosuppressive therapies can prevent acute rejection for kidney transplant recipients. Tacrolimus is usually administered to prevent graft rejection after transplantation. Previous studies have indicated that once-daily tacrolimus may improve medication adherence. Therefore, this meta-analysis aimed to compare clinical outcomes between once-daily and twice-daily tacrolimus in de novo renal transplant patients.

METHODS

Eligible studies were identified from the Cochrane Library Database, PubMed, and Embase until July 2022. Those randomized controlled trials (RCTs) evaluating once-daily versus twice-daily tacrolimus formulations in de novo renal transplantation were included. A summary risk ratio (RR) and standardized mean difference (SMD) with the 95% confidence interval (CI) were estimated using a random-effects model.

RESULTS

In total, nine RCTs were included. There were no differences in biopsy-confirmed acute rejection rates between patients with once-daily and those with twice-daily tacrolimus (RR, 0.91; 95% CI, 0.73-1.13) in 12 months. Regarding renal function, there was no significant difference between the once-daily and twice-daily tacrolimus groups (SMD, -0.03; 95% CI, -0.12 to 0.07). In addition, the risk of graft failure, death, and adverse events in the first year was similar for the once-daily and twice-daily tacrolimus groups.

CONCLUSION

Our major findings suggest that de novo renal transplantation recipients receiving once-daily tacrolimus immediately after transplantation have comparable efficacy and safety with those recipients who received twice-daily tacrolimus. Therefore, once-daily tacrolimus medication can be an alternative for de novo renal transplantation recipients.

Kidney transplant in the next decade: Strategies, challenges and vision of the future

Although the results of kidney transplantation (KT) have improved substantially in recent years, a chronic and inexorable loss of grafts mainly due to the death of the patient and chronic dysfunction of the KT, continues to be observed. The objectives, thus, to optimize this situation in the next decade are fundamentally focused on minimizing the rate of kidney graft loss, improving patient survival, increasing the rate of organ procurement and its distribution, promoting research and training in health professionals and the development of scientific registries providing clinical and reliable information that allow us to optimize our clinical practice in the field of KT. With this perspective, this review will deep into: (1) strategies to avoid chronic dysfunction and graft loss in the medium and long term; (2) to prolong patient survival; (3) strategies to increase the donation, maintenance and allocation of organs; (4) promote clinical and basic research and training activity in KT; and (5) the analysis of the results in KT by optimizing and merging scientific registries.

Envarsus XR® pharmacokinetics in adolescents post-kidney transplantation - A pilot study

INTRODUCTION

Envarsus XR® (LCPT), a once daily dosage formulation of tacrolimus, is an FDA-approved medication in adult renal transplant recipients (RTRs). There are limited data on its pharmacokinetics (PK) in adolescent RTRs. We report here the PK profile of LCPT in adolescent RTRs.

METHODS

The dose of LCPT was determined using a dose conversion ratio targeting 0.7 relative to the total daily immediate-release tacrolimus (IR-Tac) dose. On day 7 after converting to LCPT, patients had an abbreviated PK assessment with sampling at: 0 h (pre-dose), 8-, and 12-h post-dose. The PK data analysis was performed using Bayesian estimators. Our results were compared to those of published adult PK data for LCPT and pediatric PK data for IR-Tac and extended release tacrolimus (ER-Tac) formulation (Advagraf).

RESULTS

PK data from three adolescent patients on LCPT were evaluated. The mean (±SD) area under the time-concentration curve (AUC) was 240 (±20.22) h*ng/mL. The mean T_max was 9.01 ± 2.12 h, and the % fluctuation was 77.71 ± 3.96%. The AUC, T_max , and % fluctuation were similar to reported results in adult patients taking LCPT. The AUC was higher and the T_max was longer than what has been reported in pediatric patients taking IR-Tac and ER-Tac. In addition, the LCPT group showed a lower % fluctuation than patients receiving ER-Tac.

CONCLUSION

The PK evaluation of LCPT in adolescent RTRs showed similar results to adults. Adolescents taking LCPT had a higher AUC, a more attenuated T_max , and a lower fluctuation than that seen with ER-Tac in pediatrics.

Outcomes in kidney transplant recipients treated with immediate-release tacrolimus capsules versus extended-release tacrolimus capsules: A cohort study

INTRODUCTION

Prior randomized trials and observational studies have generally reported similar outcomes in kidney transplant recipients (KTRs) treated with immediate-release tacrolimus (IR-TAC) versus extended-release tacrolimus (ER-TAC). However, many of these previous studies focused on patients with low immunological risks, had small sample sizes and brief follow-up periods, and excluded outcomes associated with graft loss, such as chronic rejection.

METHODS

To address these limitations, we conducted a cohort study of 848 KTRs at a single transplantation center who had generally high immunological risks and were treated with either IR-TAC capsules (589 patients, 65.9%) or ER-TAC capsules (289 patients, 34.1%). All patients received their designated maintenance immunosuppressive regimen for at least 3 months post-transplantation. Afterwards, tacrolimus formulation was at the discretion of each patient's transplant nephrologist. For the two treatment groups, we compared the hazards of experiencing a composite outcome of acute or chronic antibody-mediated rejection (AMR), acute or chronic T-cell-mediated rejection, de novo DSA, and/or graft loss over a 3-year period starting at 3 months post-transplantation.

RESULTS

In a multivariable Cox proportional hazards regression model, KTRs treated with IR-TAC capsules had an increased hazard of experiencing the composite outcome when compared to patients treated with ER-TAC capsules; however, this result was not significant (adj HR 1.24, 95% CI .92-1.68, p = .163). Similar results were obtained with inverse probability of treatment weighting (IPTW) using a propensity score (adj HR 1.25, 95% CI .93-1.68, p = .146).

CONCLUSION

These findings suggest that when compared to IR-TAC capsules, ER-TAC capsules do not reduce the hazard of poor outcomes in KTRs with generally high immunological risks.

Comparative Study of 2 Extended-Release Tacrolimus Formulations in Kidney Transplantation

BACKGROUND

During the 1900s, tacrolimus became the mainstay immunosuppressive agent to prevent rejection after kidney transplant. Subsequently, an extended-release tacrolimus (ER-Tac) formulation was developed to improve adherence, and its generic version has been marketed over the last years. This study examines the differences in efficacy and safety between the generic ER-Tac (Conferoport) and the reference brand-name drug (Advagraf).

METHODS

Prospective, randomized and parallel single-center study (May 2020 to June 2021) with 52 kidney transplant recipients who were randomly assigned to 1 of the following groups: study group (Conferoport, n = 31) and control group (Advagraf, n = 21). The variables of interest were collected and analyzed to compare tacrolimus efficacy and safety between them. Demographic characteristics of the patients and clinical donor data were homogeneous in both groups (P > .05).

RESULTS

No statistically significant differences were found among treatments regarding dosage used, levels, creatinine, and proteinuria (P > .05), with these variables presenting a downward trend during follow-up and, consequently, the improvement of graft function. Analyses also revealed the absence of differences concerning the incidence of acute rejection and intrapatient variability (coefficient of variation) throughout the first year of evolution between both formulations (P > .05). A total of 5 graft losses occurred, 2 resulting from patient death.

CONCLUSIONS

In our experience, we found no significant differences between the measured parameters in relation to the efficacy and safety profile of both drugs, with generic ER-Tac being an alternative comparable with the reference brand-name ER-Tac.

Chronic kidney disease after lung transplantation in a changing era

Lung transplant (LTx) physicians are responsible for highly complex post-LTx care, including monitoring of kidney function and responding to kidney function loss. Better survival of the LTx population and changing patient characteristics, including older age and increased comorbidity, result in growing numbers of LTx patients with chronic kidney disease (CKD). CKD after LTx is correlated with worse survival, decreased quality of life and high costs. Challenges lie in different aspects of post-LTx renal care. First, serum creatinine form the basis for estimating renal function, under the assumption that patients have stable muscle mass. Low or changes in muscle mass is frequent in the LTx population and may lead to misclassification of CKD. Second, standardizing post-LTx monitoring of kidney function and renal care might contribute to slow down CKD progression. Third, new treatment options for CKD risk factors, such as diabetes mellitus, proteinuria and heart failure, have entered clinical practice. These new treatments have not been studied in LTx yet but are of interest for future use. In this review we will address the difficult aspects of post-LTx renal care and evaluate new and promising future approaches to slow down CKD progression.

Proposed Definitions of T Cell-Mediated Rejection and Tubulointerstitial Inflammation as Clinical Trial Endpoints in Kidney Transplantation

The diagnosis of acute T cell-mediated rejection (aTCMR) after kidney transplantation has considerable relevance for research purposes. Its definition is primarily based on tubulointerstitial inflammation and has changed little over time; aTCMR is therefore a suitable parameter for longitudinal data comparisons. In addition, because aTCMR is managed with antirejection therapies that carry additional risks, anxieties, and costs, it is a clinically meaningful endpoint for studies. This paper reviews the history and classifications of TCMR and characterizes its potential role in clinical trials: a role that largely depends on the nature of the biopsy taken (indication vs protocol), the level of inflammation observed (e.g., borderline changes vs full TCMR), concomitant chronic lesions (chronic active TCMR), and the therapeutic intervention planned. There is ongoing variability—and ambiguity—in clinical monitoring and management of TCMR. More research, to investigate the clinical relevance of borderline changes (especially in protocol biopsies) and effective therapeutic strategies that improve graft survival rates with minimal patient morbidity, is urgently required. The present paper was developed from documentation produced by the European Society for Organ Transplantation (ESOT) as part of a Broad Scientific Advice request that ESOT submitted to the European Medicines Agency for discussion in 2020. This paper proposes to move toward refined definitions of aTCMR and borderline changes to be included as primary endpoints in clinical trials of kidney transplantation.

Two-Year Outcomes of Low-Exposure Extended-Release Tacrolimus and Mycophenolate Mofetil Regimen in De Novo Kidney Transplantation: A Multi-center Randomized Controlled Trial

BACKGROUND

Once-daily extended-release tacrolimus (TACER) is commonly administered following kidney transplantation (KTx); however, its optimal dosage remains unknown.

METHODS

In this multi-center, randomized controlled trial, 62 living donor KTx recipients were assigned to either standard-exposure (SE; n = 32) or low-exposure (LE; n = 30) TACER (Graceptor®, Astellas Pharm Inc.) groups. All patients received basiliximab and mycophenolate mofetil (MMF). The primary outcomes were acute rejection, graft/patient survival, and the secondary outcomes were incidence of cytomegalovirus infection, and de novo donor-specific antibodies (dnDSA) production.

RESULTS

The tacrolimus trough level and estimated area under the blood concentration-time curve (eAUC) were significantly higher in SE than in LE (SE vs LE; one year: 5.0 ± 0.9 ng/mL and 206.9 ± 26.8 ngཥh/mL vs 3.4 ± 1.0 ng/mL and 153.9 ± 26.4 ngཥh/mL; two years: 4.8 ± 1.0 ng/mL and 204.9 ± 30.1 ngཥh/mL vs 3.8 ± 0.9 ng/mL and 164.4 ± 27.0 ngཥh/mL). In contrast, the dosage and eAUC of MMF did not differ between groups. Two-year graft and patient survival rates were 100% in both groups, and acute rejection rates were 0% and 10% in the SE and LE, respectively (p = 0.11). The mean estimated glomerular filtration rates did not differ between the groups. Cytomegalovirus infection was slightly lower in the LE (SE: 12.5% and LE: 6.7%, p = 0.37). In the LE, four cases of dnDSA were noted within two years of transplantation; no case was observed in the SE (p = 0.034).

CONCLUSIONS

Although the LE TACER regimen showed similar rates of acute rejection, as well as graft and patient survival compared with SE after KTx, LE was significantly more associated with dnDSA. Further investigation of its long-term effect on graft survival is warranted. (University Hospital Medical Information Network Clinical Trials Registry ID: UMIN000033089). This article is protected by copyright. All rights reserved.

Prolonged-Release Once-Daily Formulation of Tacrolimus Versus Standard-of-Care Tacrolimus in de novo Kidney Transplant Patients Across Europe

Background: Tacrolimus is the calcineurin inhibitor of choice for preventing acute rejection episodes in kidney transplant patients. However, tacrolimus has a narrow therapeutic range that requires regular monitoring of blood concentrations to minimize toxicity. A new once-daily tacrolimus formulation, LCP-tacrolimus (LCPT), has been developed, which uses MeltDose™ drug-delivery technology to control drug release and enhance overall bioavailability. Our study compared dosing of LCPT with current standard-of-care tacrolimus [immediate-release tacrolimus (IR-Tac) or prolonged-release tacrolimus (PR-Tac)] during the 6 months following de novo kidney transplantation. Comparisons of graft function, clinical outcomes, safety, and tolerability for LCPT versus IR-Tac/PR-Tac were also performed. Methods: Standard immunological risk patients with end-stage renal disease who had received a de novo kidney transplant were randomized (1:1) to LCPT (N = 200) or IR-Tac/PR-Tac (N = 201). Results: Least squares (LS) mean tacrolimus total daily dose from Week 3 to Month 6 was significantly lower for LCPT than for IR-Tac/PR-Tac. Although LS mean tacrolimus trough levels were significantly higher for LCPT than IR-Tac/PR-Tac, tacrolimus trough levels remained within the standard reference range for most patients. There were no differences between the groups in treatment failure measures or safety profile. Conclusion: LCPT can achieve similar clinical outcomes to other tacrolimus formulations, with a lower daily dose. Clinical Trial Registration: https://clinicaltrials.gov/, identifier NCT02432833.

Improved Kidney Allograft Function after Early Conversion of Fast IR-Tac Metabolizers to LCP-Tac

Fast tacrolimus (Tac) metabolism is associated with a more rapid decline of renal function after renal transplantation (RTx). Because the pharmacokinetics of LCP-Tac (LCPT) and immediate-release Tac (IR-Tac) differ, we hypothesized that switching from IR-Tac to LCPT in kidney transplant recipients would improve the estimated glomerular filtration rate (eGFR), particularly in fast metabolizers. For proof of concept, we performed a pilot study including RTx patients who received de novo immunosuppression with IR-Tac. A Tac concentration-to-dose ratio (C/D ratio) < 1.05 ng/mL·1/mg defined fast metabolizers and ≥1.05 ng/mL·1/mg slow metabolizers one month after RTx. Patients were switched to LCPT ≥ 1 month after transplantation and followed for 3 years. Fast metabolizers (n = 58) were switched to LCPT earlier than slow metabolizers (n = 22) after RTx (2.0 (1.0−253.1) vs. 13.2 (1.2−172.8) months, p = 0.005). Twelve months after the conversion to LCPT, Tac doses were reduced by about 65% in both groups. The C/D ratios at 12 months had increased from 0.66 (0.24−2.10) to 1.74 (0.42−5.43) in fast and from 1.15 (0.32−3.60) to 2.75 (1.08−5.90) in slow metabolizers. Fast metabolizers showed noticeable recovery of mean eGFR already one month after the conversion (48.5 ± 17.6 vs. 41.5 ± 17.0 mL/min/1.73 m², p = 0.032) and at all subsequent time points, whereas the eGFR in slow metabolizers remained stable. Switching to LCPT increased Tac bioavailability, C/D ratio, and was associated with a noticeable recovery of renal function in fast metabolizers. Conversion to LCPT is safe and beneficial early after RTx.

Bioavailability of once-daily tacrolimus formulations used in clinical practice in the management of De Novo kidney transplant recipients: the better study

Multicenter, prospective, observational study to compare the relative bioavailability of once‐daily tacrolimus formulations in de novo kidney transplant recipients. De novo kidney transplant recipients who started a tacrolimus‐based regimen were included 14 days post‐transplant and followed up for 6 months. Data from 218 participants were evaluated: 129 in the LCPT group (Envarsus) and 89 in the PR‐Tac (Advagraf) group. Patients in the LCPT group exhibited higher relative bioavailability (C_min /total daily dose [TDD]) vs. PR‐Tac (61% increase; P < .001) with similar C_min and 30% lower TDD levels (P < .0001). The incidence of treatment failure was 3.9% in the LCPT group and 9.0% in the PR‐Tac group (P = .117). Study discontinuation rates were 6.2% in the LCPT group and 12.4% in the PR‐Tac group (P = .113). Adverse events, renal function and other complications were comparable between groups. The median accumulated dose of tacrolimus in the LCPT group from day 14 to month 6 was 889 mg. Compared to PR‐Tac, LCPT showed higher relative bioavailability, similar effectiveness at preventing allograft rejection, comparable effect on renal function, safety, adherence, treatment failure and premature discontinuation rates.

De novo tacrolimus extended-release tablets (LCPT) versus twice-daily tacrolimus in adult heart transplantation: Results of a single-center non-inferiority matched control trial

Extended-release tacrolimus for prophylaxis of allograft rejection in orthotopic heart transplant (OHT) recipients is currently not FDA-approved. One such extended-release formulation of tacrolimus known as LCPT allows once-daily dosing and improves bioavailability compared to immediate-release tacrolimus (IR-tacrolimus). We compared the efficacy and safety of LCPT to IR-tacrolimus applied de novo in adult OHT recipients. Twenty-five prospective recipients on LCPT at our center from 2017 to 2019 were matched 1:2 with historical control recipients treated with IR-tacrolimus based on age, gender, and baseline creatinine. The primary composite outcome of death, acute cellular rejection, and/or new graft dysfunction within 1 year was compared using non-inferiority analysis. LCPT demonstrated non-inferiority to IR-tacrolimus, with a primary outcome risk reduction of 20% (90% CI: -40%, -.5%; non-inferiority P = .001). Tacrolimus trough levels peaked at 2-3 months and were higher in LCPT (median 14.5 vs. 12.7 ng/ml; P = .03) with similar dose levels (LCPT vs. IR-tacrolimus: .08 vs. .09 mg/kg/day; P = .33). Cardiovascular-related readmissions were reduced by 62% (P = .046) in LCPT patients. The complication rate per transplant admission and all-cause readmission rate did not differ significantly. These results suggest that LCPT is non-inferior in efficacy to IR-tacrolimus with a similar safety profile and improved bioavailability in OHT.

An Analysis of the Risk Factors for New-Onset Diabetes Mellitus After Liver Transplantation

Objective

To investigate the risk factors related to new-onset diabetes mellitus (NODM) and the significance of IL-6.

Methods

A retrospective analysis was conducted on clinical data from 64 patients who received either a living donor liver transplantation or a donation after circulatory death from September 2013 to October 2020 and attended regular follow-up visits for six or more months. During follow-up, patients were randomized into groups and followed up until the completion of the study or the death of the patient.

Results

The incidence of NODM was 31.25% (n = 20). The median age in the NODM group was 52.15 years (p < 0.01). Age (OR = 1.089; 95% CI: 0.0211-0.1495, p = 0.003) and elevated preoperative IL-6 (OR = 1.122; 95% CI: 0.0619-0.1677, p = 0.029) were found to be independent risk factors for NODM. HBV-induced liver cirrhosis, warm ischemia time (WIT), body mass index (BMI), and high preoperative fasting blood glucose (FBG) were also found to be risk factors for NODM. The recipient had a higher risk of NODM if the donor had a high BMI and poor hepatic function. The concentrations of IL-6, procalcitonin (PCT), FBG, and tacrolimus (TAC) in the first month postoperatively were significantly higher in the NODM group than in the NO-NODM group. The survival rate of the patients was not affected by NODM.

Conclusion

HBV-induced liver cirrhosis, WIT, BMI, and high preoperative FBG levels are risk factors for NODM, and age and preoperative IL-6 levels are independent risk factors. To a certain extent, higher BMI and poor hepatic function had reference significance for the incidence of NODM. Patients with a high concentration of FBG, IL-6, and TAC in the first month postoperatively had an increased risk of suffering from NODM.

Comparing the pharmacokinetics of extended-release tacrolimus (LCP-TAC) to immediate-release formulations in kidney transplant patients

INTRODUCTION

One of the most commonly used immunosuppressants in organ transplant, tacrolimus exhibits wide interpatient and intrapatient variability and narrow therapeutic index that necessitates routine concentration monitoring and dosage adjustments. Availability of modified -release tacrolimus products offer once-daily dosing options. The objective of this review is to highlight and compare available pharmacokinetic (PK) data of extended-release tacrolimus tablets (LCP-TAC) to immediate-release tacrolimus (IR-TAC) in kidney transplant recipients.

AREAS COVERED

A review of the literature was performed using PubMed and Embase search to identify relevant articles evaluating PK data for LCP-TAC compared to IR-TAC in kidney transplant patients including special populations.

EXPERT OPINION

LCP-TAC's unique PK profile may be more favorable than IR-TAC. While the clinical impact of these PK differences have not been established, several outcomes are being evaluated in ongoing studies. Results of these studies will add information incrementally to care for kidney transplant patients. Larger prospective studies evaluating kidney and patient survival differences are needed but it is unlikely that they will be conducted. Given that the patent exclusivity of LCP-TAC for the next several years and imminent loss of exclusivity of PR-TAC, our opinion is the use of LCP-TAC will be increasing, especially in Europe.

The Tacrolimus Metabolism Rate and Dyslipidemia after Kidney Transplantation

Fast tacrolimus (Tac) metabolism is associated with reduced survival rates after renal transplantation (RTx), mainly due to cardiovascular events. Because dyslipidemia is a leading cause of cardiovascular death, we hypothesized that most RTx patients do not achieve recommended target low-density lipoprotein cholesterol (LDL-C) levels (European cardiology society guidelines) and that fast Tac metabolizers have higher dyslipidemia rates. This study included RTx recipients who received initial immunosuppression with immediate-release tacrolimus (IR-Tac), mycophenolate, and prednisolone. Patients were grouped according to their Tac concentration-to-dose ratio (C/D ratio) 3 months after RTx. Dyslipidemia parameters were analyzed at RTx, 3 months, and 12 months after RTx. Statin use and renal function were documented in a 12-month follow-up, and death was documented in a 60-month follow-up. Ninety-six RTx recipients were divided into two groups: 31 fast Tac metabolizers (C/D ratio < 1.05 ng/mL·1/mg) and 65 slow metabolizers (C/D ratio ≥ 1.05 ng/mL·1/mg). There were no differences in triglyceride or cholesterol levels between groups at RTx, 3, and 12 months after RTx. A total of 93.5% of fast and 95.4% of slow metabolizers did not achieve target LDL-C levels (p = 0.657). Fast metabolizers developed lower renal function compared to slow metabolizers 12 months after RTx (p = 0.009). Fast metabolizers showed a 60 month survival rate of 96.8% compared to 94.7% in the slow metabolizer group (p = 0.811). As most RTx recipients do not reach recommended target LDL-C levels, individualized nutritional counseling and lipid-lowering therapy must be intensified. Fast Tac metabolism is associated with lower renal function after RTx, but does not play a significant role in dyslipidemia.

Cost-effectiveness of once-daily vs twice-daily tacrolimus among Hispanic and Black kidney transplant recipients

BACKGROUND: Tacrolimus is a first-line immunosuppressive therapy to prevent rejection and graft failure in kidney transplant recipients. Once-daily extended-release tacrolimus tablets (LCPT) have been shown to be efficacious, particularly for Hispanic and Black patient subpopulations who are rapid metabolizers, but is more costly than twice-daily immediate-release tacrolimus (IR-Tac). OBJECTIVE: To evaluate the cost-effectiveness of LCPT during the first year of treatment vs IR-Tac in kidney transplant recipients who are Hispanic or Black. METHODS: A decision analytic model from a US payer perspective was developed using (1) subgroup outcomes data pooled from two phase 3 clinical trials that compared LCPT and IR-Tac, and (2) direct costs from real-world data sources (ie, costs of LCPT and IR-Tac treatments, biopsy-proven acute rejection, treatment-related serious adverse events [SAEs], graft failure, and consequent dialysis). The primary outcome was cost per successfully treated patient, defined as having a functioning graft after 1 year and without treatment-related SAEs. Probabilistic sensitivity analyses established distributions for cost and outcomes estimates, and a series of one-way sensitivity analyses identified parameters that had the most effect on results. RESULTS: Total overall cost for the Hispanic group was $14,765 for LCPT and $12,416 for IR-Tac, and total cost in the Black group was $16,626 for LCPT and $9,871 for IR-Tac. Total overall effectiveness of LCPT and IR-Tac was 88.32% and 84.75% in the Hispanic group and 93.24% and 85.78% in the Black group, respectively. The incremental cost-effectiveness ratio (ICER) for using LCPT over IR-Tac during the first year of treatment in the Hispanic group was $65,643 per additional successfully treated patient. The ICER for the Black group was $90,458. The single parameter having the most impact on results in both groups was the probability of a treatment-related SAE in IR-Tac, which accounted for 49% of variation in results in the Hispanic group and 46% in the Black group. CONCLUSIONS: Overall results for both groups show that LCPT is incrementally more costly and more effective compared with IR-Tac, indicating a trade-off scenario. LCPT is a cost-effective strategy if a decision makers' willingness to pay for 1 additional successfully treated patient exceeds the ICER and must be weighed against the costs of graft loss, continuing dialysis, and potential retransplant. This study provides a foundation for further research to update and expand inputs as more data become available to improve real-world relevance and decision making. DISCLOSURES: This study was funded by Veloxis Pharmaceuticals, Inc., which provided clinical trial file data and nonbinding feedback on the model structure, data interpretation, clinical expertise, manuscript review, and areas of publication interest (ie, managed care). Hurwitz, Grizzle, Villa Zapata, and Malone received grant funding from Veloxis Pharmaceuticals, Inc., through University of Arizona to conduct research and analysis for this study. Tyler is employed by Veloxis Pharmaceuticals, Inc. Some of the data reported and used in this research were available from the US Renal Data System, the US Bureau of Labor Statistics, and the Agency for Healthcare Research and Quality's Healthcare Cost and Utility Project. The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy or interpretation of the US government.

Efficacy and Safety of Once-Daily LCP-Tacrolimus Versus Twice-Daily Immediate-Release Tacrolimus in Adult Hispanic Stable Kidney Transplant Recipients: Sub-Group Analysis from a Phase 3 Trial

BACKGROUND The pharmacokinetics and metabolism of tacrolimus, an immunosuppressant commonly used to prevent transplant rejection, can differ in specific subpopulations. This analysis examined treatment outcomes and safety of immediate-release tacrolimus (IR-Tac) and LCP-tacrolimus (LCPT) in stable Hispanic kidney transplant recipients. MATERIAL AND METHODS This was a post hoc analysis of clinical trial data from Hispanic adult stable kidney transplant recipients randomized to remain on IR-Tac or convert from IR-Tac to a reduced dose of LCPT (NCT00817206). Composite treatment failure was evaluated at 12 months. Estimated glomerular filtration rate and tacrolimus trough concentrations were evaluated over 12 months. RESULTS Fifty-five stable (LCPT n=26, IR-Tac n=29) kidney transplant recipients who self-identified as Hispanic or Latino were included in this analysis. Composite treatment failure occurred in 1 patient (4%) who converted to LCPT and 1 (3%) who remained on IR-Tac. The estimated glomerular filtration rate was stable over time and similar in the 2 treatment groups (P=0.08). Tacrolimus trough levels for both groups were similar over time in the 2 treatment groups (P=0.98). Treatment-emergent adverse events were similar in patients who converted to LCPT and in those who remained on IR-Tac. CONCLUSIONS Efficacy and safety were similar in Hispanic kidney transplant recipients who converted from IR-Tac to LCPT and in those remaining on IR-Tac.

Clinical Experience with Extended-Release Tacrolimus in Older Adult Kidney Transplant Recipients: A Retrospective Cohort Study

BACKGROUND

Extended-release tacrolimus (LCP-Tac) prescribing information states that there is insufficient data in older adult patients from which to make recommendations on use in this population. This study sought to provide information on de novo use of LCP-Tac in the older adult kidney transplant population.

METHODS

This single-center retrospective study had two distinct objectives; to determine if weight-based doses of LCP-Tac differ based on recipient age and to compare safety and efficacy between LCP-Tac and immediate-release tacrolimus (IR-Tac) in older adult transplant recipients. Data was obtained through electronic chart review up to 2 years after transplant with censoring for graft loss and death.

RESULTS

Weight-based doses were compared between patients aged ≥ 65 years (n = 84), 36-64 years (n = 64), and ≤35 years (n = 44). LCP-Tac weight-based doses were lower at all time points in patients ≥ 65 years of age. Both age and race significantly impacted required dose on linear regression. The doses required to achieve therapeutic tacrolimus troughs were significantly lower in all age groups compared with the current FDA de novo dosing recommendation. In the older adult population, graft outcomes and infectious and metabolic complications were compared between recipients of LCP-Tac (n = 84) and IR-Tac (n = 42). Within this cohort, there were no differences between LCP-Tac and IR-Tac on graft function, rejection, graft loss, death, cytomegalovirus viremia, BK viremia, hypertension, diabetes, alopecia, or tremor up to 2 years after transplant.

CONCLUSIONS

Older adult recipients required significantly lower LCP-Tac doses compared with younger recipients and with the FDA-labeled starting dose. There were no differences in graft outcomes or adverse effects in older adult patients who received LCP-Tac versus IR-Tac.

Thirty Years of Tacrolimus in Clinical Practice

Tacrolimus was discovered in 1984 and entered clinical use shortly thereafter, contributing to successful solid organ transplantation across the globe. In this review, we cover development of tacrolimus, its evolving clinical utility, and issues affecting its current usage. Since earliest use of this class of immunosuppressant, concerns for calcineurin-inhibitor toxicity have led to efforts to minimize or eliminate these agents in clinical regimens but with limited success. Current understanding of the role of tacrolimus focuses more on its efficacy in preventing graft rejection and graft loss. As we enter the fourth decade of tacrolimus use, newer studies utilizing novel combinations (as with the mammalian target of rapamycin inhibitor, everolimus, and T-cell costimulation blockade with belatacept) offer potential for enhanced benefits.

Differential Effect of a Continental Breakfast on Tacrolimus Formulations With Different Release Characteristics

Food reduces tacrolimus bioavailability after immediate-release tacrolimus (IR-Tac) and after a new prolonged-release tacrolimus formulation (PR-Tac), when using a high-fat breakfast, but the effects of a continental breakfast on PR-Tac are unknown. In an open-label, 4-phase, randomized, 2-sequence, crossover pharmacokinetic trial, 36 healthy volunteers (18 females) received single 5-mg tacrolimus doses as PR-Tac and as IR-Tac fasted or with a standardized continental breakfast. Tacrolimus pharmacokinetics were analyzed using noncompartmental methods and mixed-model analysis of variance. The continental breakfast significantly decreased average tacrolimus exposure (area under the plasma concentration-time curve) with both preparations (IR-Tac, 67%; 90% confidence interval [CI], 59%-75%; P < .01; and PR-Tac, 79%; 90%CI, 70%-89%; P < .01) with a nonsignificant difference between both preparations (P = .10). The maximum concentration (C_max ) and the time to maximum concentration (t_max ) were significantly affected only after IR-Tac (C_max IR-Tac, 39%; 90%CI, 34%-45%; P < .01; and PR-Tac, 87%; 90%CI, 76%-101%; P = .11; t_max IR-Tac, 212%, 90%CI, 179%-252%; P < .01; and PR-Tac, 101%; 90%CI, 86%-120%; P = .89), which was significantly different between both preparations (P < .01). Considering switching from IR-Tac to PR-Tac, predicted dose requirements differed according to the timing of drug intake in relation to food. In conclusion, a continental breakfast decreased average tacrolimus exposure of both preparations to a similar extent. C_max and t_max were affected only after IR-Tac. The effect of a standardized continental breakfast on PR-Tac was considerably smaller than previously reported effects of a high-fat breakfast on PR-Tac.

Real-World Administration of Once-Daily MeltDose® Prolonged-Release Tacrolimus (LCPT) Allows for Dose Reduction of Tacrolimus and Stabilizes Graft Function Following Liver Transplantation

The calcineurin inhibitor tacrolimus is included in most immunosuppressive protocols after liver transplantation. This retrospective, observational 24-month study investigated the tolerability of once-daily MeltDose^® prolonged-release tacrolimus (LCPT) after switching from twice-daily immediate-release tacrolimus (IR-Tac) in a real-world cohort of 150 patients with previous liver transplantation. No graft rejection or new safety signals were observed. Only 7.3% of patients discontinued LCPT due to side effects. In the overall patient population, median liver transaminases, total cholesterol, triglycerides, glucose, and HbA_1c remained constant after switching to LCPT. Total cholesterol significantly decreased (p ≤ 0.002) in patients with initially elevated levels (>200 mg/dL). A total of 71.8% of 96 patients maintained a glomerular filtration rate > 60 mL/min/1.73 m² throughout the study, while 44.7% of patients were classified as fast metabolizers and 55.3% as slow metabolizers. Median daily tacrolimus dose could be reduced by 50% in fast metabolizers and by 30% in slow metabolizers, while trough levels were maintained in the target range (4–6 ng/mL). In conclusion, our observational study confirmed previous evidence of good overall tolerability and a favorable outcome for the patients after switching from IR-Tac to LCPT after liver transplantation.

pre-existing diabetes and PTDM in kidney transplant recipients: how to handle immunosuppression

INTRODUCTION

Preexisting diabetes (PD) and post-transplant diabetes mellitus (PTDM) are common and severe comorbidities posttransplantation. The immunosuppressive regimens are modifiable risk factors.

AREAS COVERED

We reviewed Pubmed and Cochrane database and we summarize the mechanisms and impacts of available immunosuppressive treatments on the risk of PD and PTDM. We also assess the possible management of these drugs to improve glycemic parameters while considering risks inherent in transplantation.

EXPERT OPINION

PD i) increases the risk of sepsis, ii) is an independent risk factor for infection-related mortality, and iii) increases acute rejection risk. Regarding PTDM development i) immunosuppressive strategies without corticosteroids significantly reduce the risk but the price may be a higher incidence of rejection; ii) minimization or rapid withdrawal of steroids are two valuable approaches; iii) the diabetogenic role of calcineurin inhibitors(CNIs) is also well-described and is more important for tacrolimus than for cyclosporine. Reducing tacrolimus-exposure may improve glycemic parameters but also has a higher risk of rejection. PTDM risk is higher in patients that receive sirolimus compared to mycophenolate mofetil. Finally, conversion from CNIs to belatacept may offer the best benefits to PTDM-recipients in terms of glycemic parameters, graft and patient-outcomes.

Comparison of the Impact of Pharmacogenetic Variability on the PK of Slow Release and Immediate Release Tacrolimus Formulations

Tacrolimus-modified release formulations allow for once-daily dosing, and adherence is better compared to the twice-daily immediate release formulation. When patients are switched from one formulation to another, variable changes in drug concentrations are observed. Current data suggest that the changes in drug exposure are larger in patients who express the CYP3A5 enzyme (CYP3A5 *1/*3 or *1/*1) compared to nonexpressers (CYP3A5*3/*3). Possibly, these differences are due to the fact that in the upper region of the small intestine CYP3A activity is higher, and that this expression of CYP3A decreases towards the more distal parts of the gut. Modified release formulations may therefore be subject to a less presystemic metabolism. However, the full implications of pharmacogenetic variants affecting the expression and function of drug transporters in the gut wall and of enzymes involved in phase I and phase II metabolism on the different formulations are incompletely understood, and additional studies are required. Conclusions: In all patients in whom the formulation of tacrolimus is changed, drug levels need to be checked to avoid clinically relevant under- or overexposure. In patients with the CYP3A5 expresser genotype, this recommendation is even more important, as changes in drug exposure can be expected.

Evaluation of the impact of Tacrolimus-based immunosuppression on Heidelberg liver transplant cohort (HDTACRO): Study protocol for an investigator initiated, non-interventional prospective study

BACKGROUND

Tacrolimus-based immunosuppression has resulted in enormous improvements on liver transplantation (LTx) outcomes. However, dose adjustment and medication adherence play a key role in post-transplant treatment success. The aim of the present study is to assess the trough levels and the need for adaptation of therapeutic doses in de novo LTx patients treated with Tacrolimus in the clinical routine, without any intervention to the treatment regimen.

METHODS AND ANALYSIS

This is a pilot, prospective, exploratory, monocentric, non-interventional and non-randomized investigator-initiated study. Prospectively maintained data of 100 patients treated with various oral Tacrolimus-based immunosuppressants (Prograf or Envarsus) will be analyzed. The number of required dose adjustments of Tacrolimus formulations used in clinical routine for achieving the target trough level, Tacrolimus trough level, Tacrolimus dosing, concentration/dose ratio, routine laboratory tests, efficacy data (incl. survival, acute rejection, re-transplantation), patients therapy adherence, and infections requiring the need to reduce individual immunosuppressant dosing will be evaluated for each patient.

RESULT

This study will evaluate the trough levels and the need for adaptation of therapeutic doses in de novo LTx patients treated with Tacrolimus in the clinical routine, without any intervention to the treatment regimen.

CONCLUSION

The HDTACRO study will be the first study to systematically and prospectively evaluate various oral Tacrolimus-based immunosuppressants in de novo liver transplanted patients. If a difference between the therapy-subgroups is evident at the end of the trial, a randomized control trial will eventually be designed. Registration number: ClinicalTrials.gov: NCT04444817.

Effect of Concentration/Dose Ratio in De Novo Kidney Transplant Recipients Receiving LCP-Tacrolimus or Immediate-Release Tacrolimus: Post Hoc Analysis of a Phase 3 Clinical Trial

Background

A previous phase 3 clinical trial in de novo adult kidney transplant recipients (NCT01187953) compared the efficacy and safety of once-daily LCP-tacrolimus (LCPT) and twice-daily immediate-release tacrolimus (IR-Tac). However, whether the rate of tacrolimus metabolism affects outcomes between LCPT and IR-Tac was not examined.

Material/Methods

Patients were initiated on 0.17 mg/kg/day LCPT or 0.1 mg/kg/day IR-Tac, with doses adjusted over time to maintain target therapeutic trough concentrations. This post hoc analysis examined dosing trends, relative efficacy, and safety of LCPT (n=247) and IR-Tac (n=249) in slow, intermediate, and rapid metabolizers as defined by concentration/dose ratios at day 30.

Results

For all metabolizer subgroups, minimum target tacrolimus trough concentrations were obtained more rapidly with LCPT than with IR-Tac. Slow metabolizers were more likely to exceed target trough concentrations with LCPT, while rapid metabolizers were more likely to fall below target trough concentrations with IR-Tac. Regardless of metabolizer status, significant differences were not detected between LCPT and IR-Tac for treatment failure, death, graft failure, biopsy-proven acute rejection, estimated glomerular filtration rate, or other clinical outcomes.

Conclusions

Although within metabolizer subgroups, attainment of target trough concentrations in the first week differed between LCPT and IR-Tac, these results suggest that, regardless of metabolizer phenotype, clinical outcomes do not differ between these formulations when dose adjustments are made.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT01187953

The Effect of Maintenance Treatment with Twice-Daily or Prolonged Once-Daily Tacrolimus Formulation on Visual Evoked Potentials in Stable Kidney Transplant Recipients

In kidney transplant recipients (KTRs), uraemia-induced central nervous system damage partly subsides, while the long-lasting exposure to tacrolimus may cause pathologic visual evoked potentials (VEP) findings, which have not been investigated yet. Thus, the aim of the present study was to assess the effect of tacrolimus maintenance treatment on bioelectrical function of optic nerves in stable KTRs. Sixty-five stable KTRs were enrolled, including 30 patients treated with twice-daily (Prograf) and 35 patients treated with prolonged once-daily (Advagraf) tacrolimus formulation. In all patients, pattern and flash VEP measurements were performed. Tacrolimus dosing and exposure were also analyzed. Overall, 129 eyes were analyzed. In pattern VEP, both (1°) and (15') latencies of P100 waves were significantly longer, whereas (1°) and (15') amplitudes were lower in the Advagraf group as compared with the Prograf group. Multivariate regression analyses revealed that the use of Advagraf (vs. Prograf) was independently associated with longer (1°) and (15') P100 latencies and lower corresponding amplitudes, whereas log tacrolimus daily dose was only related to amplitudes in a whole study group. In flash VEP, log tacrolimus trough level was associated with negative changes in P2 wave amplitude irrespective of tacrolimus formulation, whereas its association with P2 latency was observed only in the Prograf group. Both the type of tacrolimus formulation and drug exposure influenced the VEP parameters in stable KTRs.

Conversion from Standard-Release Tacrolimus to MeltDose® Tacrolimus (LCPT) Improves Renal Function after Liver Transplantation

Renal impairment is a typical side effect of tacrolimus (Tac) treatment in liver transplant (LT) recipients. One strategy to avoid renal dysfunction is to increase the concentration/dose (C/D) ratio by improving drug bioavailability. LT recipients converted from standard-release Tac to MeltDose^® Tac (LCPT), a novel technological formulation, were able to reduce the required Tac dose due to higher bioavailability. Hence, we hypothesize that such a conversion increases the C/D ratio, resulting in a preservation of renal function. In the intervention group, patients were switched from standard-release Tac to LCPT. Clinical data were collected for 12 months after conversion. Patients maintained on standard-release Tac were enrolled as a control group. Twelve months after conversion to LCPT, median C/D ratio had increased significantly by 50% (p < 0.001), with the first significant increase seen 3 months after conversion (p = 0.008). In contrast, C/D ratio in the control group was unchanged after 12 months (1.75 vs. 1.76; p = 0.847). Estimated glomerular filtration rate (eGFR) had already significantly deteriorated in the control group at 9 months (65.6 vs. 70.6 mL/min/1.73 m² at study onset; p = 0.006). Notably, patients converted to LCPT already had significant recovery of mean eGFR 6 months after conversion (67.5 vs. 65.3 mL/min/1.73 m² at study onset; p = 0.029). In summary, conversion of LT recipients to LCPT increased C/D ratio associated with renal function improvement.

Mitigation of Tacrolimus-Associated Nephrotoxicity by PLGA Nanoparticulate Delivery Following Multiple Dosing to Mice while Maintaining its Immunosuppressive Activity

The aim of this study was to assess the ability of PLGA nanoparticles (NPs) to reduce the tacrolimus (TAC)-associated nephrotoxicity following multiple dose administration. The mean diameter of prepared NPs was in the range of 227 to 263 nm with an 8.32% drug loading (w/w). Moreover, in vitro release profile of TAC-loaded NPs showed a sustained release of the drug with only less than 30% release within 12 days. Flow cytometry as well as fluorescence microscopy results confirmed the uptake of FITC-labelled PLGA NPs by dendritic cells. The ex vivo study showed that TAC-loaded NPs caused a significant suppression of the proliferation of CD4⁺ and CD8⁺ cells, which was comparable to the control formulation (Prograf). In vivo immunosuppressive activity as well as the kidney function were assessed following drug administration to mice. The animals received TAC subcutaneously at a daily dose of 1 mg/kg for 30 days delivered as the control formulation (Prograf) or TAC-loaded NPs. The results revealed significantly lower drug-associated toxicity with an activity comparable to Prograf for TAC-loaded PLGA NPs. These findings show a potential for PLGA NPs in reducing the nephrotoxicity of TAC while preserving the immunosuppressive activity.

Non-linear Relationship between Tacrolimus Blood Concentration and Acute Rejection After Kidney Transplantation: A Systematic Review and Dose-Response Meta-Analysis of Cohort Studies

BACKGROUND

Maintaining the exposure of tacrolimus (Tac) after kidney transplantation (KT) must be necessary to prevent acute rejection (AR) and improve graft survival，but there is still no clear consensus on the optimal Tac target blood concentration and concentration-effect relationship is poorly defined.

METHODS

We conducted a dose-response meta-analysis to quantitatively assess the association between Tac blood concentration and (AR) or adverse effects after KT. A comprehensive search of PubMed, Embase and Cochrane library databases was conducted to find eligible studies up to 10th September 2018. Unpublished data from patients receiving KT in West China Hospital (Sichuan University, China) were also collected. Both twostage dose-response and one-stage dose-response meta-analysis models were used to improve the statistical power.

RESULTS

A total of 4967 individuals from 10 original studies and 1453 individuals from West China Hospital were eligible for the ultimate analysis. In the two-stage dose-response meta-analysis model, we observed a significant non-linear relationship between Tac blood concentration and AR (P < 0.001) with moderate heterogeneity (I2 = 46.0%, P = 0.08). Tac blood concentration at 8ng/ml was associated with the lowest risk of AR (RR: 0.26, 95%CI: 0.13 - 0.54) by reference to 2ng/ml. Tac concentration at 7.0 - 11.0 ng/ml reduced the risk of AR by at least 70%, 5-14 ng/ml by at least 60%, and 4.5 - 14 ng/ml at least 50%. In the one-stage dose-response model, we also found a strong non-linear relationship between Tac and AR (P < 0.001) with moderate heterogeneity (I2 = 41.2%, P = 0.10). Tac concentration of 7.5 ng/ml was associated with the lowest risk of AR (RR: 0.35, 95%CI: 0.16 - 0.77). The blood concentration at 5.5 - 9.5 ng/ml was associated with the reduced AR by at least 60% and 4.5 - 10.5 ng/ml by at least 50% by reference to 2 ng/ml.

CONCLUSION

Maintaining Tac blood concentration at 5 - 9.5 ng/ml within the first year may prevent AR most effectively.