Tacrolimus Exposure Research Articles

Examination of the Impact of CYP3A4/5 on Drug–Drug Interaction between Schizandrol A/Schizandrol B and Tacrolimus (FK-506): A Physiologically Based Pharmacokinetic Modeling Approach

Schizandrol A (SZA) and schizandrol B (SZB) are two active ingredients of Wuzhi capsule (WZC), a Chinese proprietary medicine commonly prescribed to alleviate tacrolimus (FK-506)-induced hepatoxicity in China. Due to their inhibitory effects on cytochrome P450 (CYP) 3A enzymes, SZA/SZB may display drug–drug interaction (DDI) with tacrolimus. To identify the extent of this DDI, the enzymes’ inhibitory profiles, including a 50% inhibitory concentration (IC50) shift, reversible inhibition (RI) and time-dependent inhibition (TDI) were examined with pooled human-liver microsomes (HLMs) and CYP3A5-genotyped HLMs. Subsequently, the acquired parameters were integrated into a physiologically based pharmacokinetic (PBPK) model to quantify the interactions between the SZA/SZB and the tacrolimus. The metabolic studies indicated that the SZB displayed both RI and TDI on CYP3A4 and CYP3A5, while the SZA only exhibited TDI on CYP3A4 to a limited extent. Moreover, our PBPK model predicted that multiple doses of SZB would increase tacrolimus exposure by 26% and 57% in CYP3A5 expressers and non-expressers, respectively. Clearly, PBPK modeling has emerged as a powerful approach to examine herb-involved DDI, and special attention should be paid to the combined use of WZC and tacrolimus in clinical practice.

High intrapatient variability of tacrolimus exposure associated with poorer outcomes in liver transplantation.

Tacrolimus (TAC) is a dose‐dependent immunosuppressor with considerable intrapatient variability (IPV) in its pharmacokinetics. The aim of this work is to ascertain the association between TAC IPV at 6 months after liver transplantation (LT) and patient outcome. This single‐center cohort study retrospectively analyzed adult patients who underwent transplantation from 2015 to 2019 who survived the first 6 months with a functioning graft. The primary end point was the patient’s probability of death and the secondary outcome was the loss of renal function between month 6 and the last follow‐up. TAC IPV was estimated by calculating the coefficient of variation (CV) of the dose‐corrected concentration (C0/D) between the third and sixth months post‐LT. Of the 140 patients who underwent LT included in the study, the low‐variability group (C0/D CV < 27%) comprised 105 patients and the high‐variability group (C0/D CV ≥ 27%) 35 patients. One‐, 3‐, and 5‐year patient survival rates were 100%, 82%, and 72% in the high‐variability group versus 100%, 97%, and 93% in the low‐variability group, respectively (p = 0.005). Moreover, significant impaired renal function was observed in the high‐variability group at 1 year (69 ± 16 ml/min/1.73 m2 vs. 78 ± 16 ml/min/1.73 m2, p = 0.004) and at 2 years post‐LT (69 ± 17 ml/min/1.73 m2 vs. 77 ± 15 ml/min/1.73 m2, p = 0.03). High C0/D CV 3–6 months remained independently associated with worse survival (hazard ratio = 3.57, 95% CI = 1.32–9.67, p = 0.012) and loss of renal function (odds ratio = 3.47, 95% CI = 1.30–9.20, p = 0.01). Therefore, high IPV between the third and sixth months appears to be an early and independent predictor of patients with poorer liver transplant outcomes.

High Tacrolimus Intrapatient Variability and Subtherapeutic Immunosuppression are Associated With Adverse Kidney Transplant Outcomes.

Kidney transplant recipients with high intrapatient variability (IPV) in tacrolimus (Tac) exposure experience more rejection and reduced graft survival. To understand the underlying pathophysiology of this association, the authors investigated whether patients with high tacrolimus IPV have a more activated immune system than patients with low IPV. In addition, exposure to tacrolimus and mycophenolic acid (MPA) was studied in relation to rejection and graft survival. At the time of patient inclusion (5-7 years post-transplantation), the frequency of donor-reactive cells was determined by enzyme-linked immunosorbent assay, and the development of donor-specific anti-Human Leukocyte Antigen antibodies (DSA) was measured by Luminex Single Antigen assay. Tacrolimus IPV was retrospectively calculated between 6 and 12 months and the exposure to tacrolimus and MPA was determined between 1 and 5 years post-transplantation. A total of 371 kidney transplant recipients were included in this study, of whom 56 developed a rejection episode after 12 months and 60 experienced graft failure after 5-7 years. No correlations were found between tacrolimus IPV or immunosuppression exposure and the number of donor-reactive cells after 5 years of transplantation. DSA were detected more often in patients with low exposure to both tacrolimus and MMF [4/21 (19%) versus 17/350 (4.9%), P = 0.04]. In this cohort, neither tacrolimus IPV nor low overall immunosuppression exposure was associated with a higher incidence of rejection. However, regression analysis showed that a higher tacrolimus IPV was associated with an increased incidence of graft failure (odds ratio = 1.03, P = 0.02). This study verifies the relationship between high tacrolimus IPV and impaired kidney allograft survival in long-term follow-up. DSA was also found to be more prevalent in patients with subtherapeutic concentrations of tacrolimus and MPA. An increased prevalence of donor-specific alloreactivity is yet to be demonstrated in patients with high IPV.

Carcinogenicity risk associated with tacrolimus use in kidney transplant recipients: a systematic review and meta-analysis.

BackgroundCurrently, tacrolimus is the preferred anti-rejection therapy for kidney transplant recipients due to its greater protection against acute rejections compared to cyclosporin A (CsA). Despite the advantages of kidney transplantation, it has been associated with an increased incidence of de novo malignancies. Furthermore, a systematic review in 2005 revealed no statistical difference in tumorigenicity between tacrolimus and CsA. This report provides an up to date systematic review and evaluation of all relevant studies in the literature to determine the risk of malignancy in kidney transplant recipients exposed to tacrolimus.MethodsA systematic literature search was performed using the Medline (PubMed and Ovid), Embase, Clinical Trials, and Cochrane databases (from creation to May 2021). We performed a meta-analysis of 11 studies with 36,985 kidney transplant recipients that compared the tacrolimus group with the control group. Outcomes of this study were incidence of malignancies and skin cancer risk. Risk of Bias was assessed in terms of whether there was random sequence generation, allocation concealment, blinding, completeness of results, selective reporting, etc. This meta-analysis was performed in accordance with PRISMA guidelines.ResultsOf the 11 included studies, 8 were high quality studies, 1 was assessed as medium quality, and 2 were low quality studies. The results showed a significantly increased risk of overall malignancy associated with tacrolimus exposure compared to non-tacrolimus therapy [risk ratio (RR) =1.59; 95% confidence interval (CI): 1.19–2.11; P=0.002], and especially with sirolimus (SRL) (RR =2.58; 95% CI: 1.62–4.09; P<0.0001). The incidence of skin cancer was consistent with the overall study (RR =2.03; 95% CI: 1.25–3.28; P=0.004). However, there was no significant difference in the incidence of tumors between tacrolimus and cyclosporine A treatment (RR =1.12; 95% CI: 0.80–1.56; P=0.52), even in studies with long follow-up periods of more than 3 years.DiscussionThe data demonstrated that patients treated with tacrolimus had a higher risk of carcinogenicity compared to patients treated with SRL. However, patients treated with tacrolimus had a similar incidence of carcinogenicity compared to patients treated with CsA. Further clinical studies are warranted to confirm these findings.

Differences in kinetics of tacrolimus concentration after letermovir discontinuation by type of concomitant azole antifungal.

Letermovir is commonly used for CMV prophylaxis after allogeneic hematopoietic cell transplantation (HCT). Pharmacokinetic studies have shown an increase in tacrolimus exposure among healthy volunteers who took letermovir. However, studies in HCT recipients are needed because these patients are typically using concomitant antifungals with different degrees of CYP3A4 inhibition that may further interact with tacrolimus pharmacokinetics. In this study, we retrospectively evaluated the kinetics of tacrolimus concentration after letermovir discontinuation by type of concomitant azole antifungal in 57 HCT recipients. The median fold change in tacrolimus concentration-to-dose (C/D) ratio after discontinuing letermovir was 0.64 (range 0.43-0.99) with fluconazole and 1.10 (range 0.59-1.73) with voriconazole (p < 0.001). The tacrolimus C/D ratio decreased ≥ 30% after discontinuing letermovir (p < 0.001) in 66% of patients on fluconazole and 9% on voriconazole. Among patients whose tacrolimus C/D ratio decreased ≥ 30%, three (9%) patients in the fluconazole group and one (4%) in the voriconazole group experienced worsening of GVHD. Careful monitoring of tacrolimus concentration is important after letermovir discontinuation to avoid worsening of GVHD due to decreased tacrolimus concentration.

Time within therapeutic range: A comparison of three tacrolimus formulations in renal transplant recipients

Background: Currently there are three available formulations of tacrolimus in the United States; these include immediate-release capsules (TAC-IR), extended-release capsules (TAC-XL), and extended-release tablets (TAC-XR). Previous studies have demonstrated non-inferiority between the three formulations in terms of efficacy. The purpose of this study was to compare three formulations of tacrolimus (TAC) and assess differences in time within the therapeutic range (TTR) and variability in levels. Results: Renal transplant recipients from January 2013 to October 2017 were retrospectively identified for analysis. Deviation from standard TAC protocol or formulation changes excluded patients. The primary outcome compared percent TTR (TTR %) among 3 TAC formulations over the first 90 days post-transplant. TTR was calculated using the Rosendaal method. Secondary outcomes included differences in TAC levels, TAC dose, eGFR, rejection, patient and graft survival between the TAC formulations. TAC-XR demonstrated a significantly higher TTR % compared to TAC-IR and TAC-XL (62.8% vs. 53.3% vs. 60.9%, p = 0.048). In post-hoc analysis, TAC-XR had a higher TTR % compared to TAC-IR (p = 0.065), which approached statistical significance. Average TAC levels, weight-normalized TAC doses, median dose-normalized TAC levels, rejection rates, eGFR, and graft or patient survival were similar among groups. Conclusion: In the early transplant period, TTR was significantly different among the groups. TAC-XR demonstrated numerically superior time within the therapeutic range. Patient-specific factors such as race, obesity, genetic polymorphisms may impact this variability and clinical outcomes. Further analysis is necessary to understand the effect of each patient-specific factor on TAC exposure.

Efficacy and Outcomes of CYP3A5 Genotype-Based Tacrolimus Dosing Compared to Conventional Body Weight-based Dosing in Living Donor Kidney Transplant Recipients.

Introduction:Clinical use of tacrolimus has been challenging due to its narrow therapeutic index and highly variable pharmacokinetics. In this study, we compared patients who received body weight-based tacrolimus dosing pre-transplant (transplanted from 2016 to 2018) with those who received CYP3A5 genotype-based dosing (2018 to 2020).Methods:Eighty-two renal transplant recipients were non-randomly assigned to genotype-adapted or bodyweight-based tacrolimus dosing groups. The primary end point was to study the proportion of subjects who achieved the target tacrolimus C0 on post-op day 4. Secondary end points included clinical outcomes and safety.Results:The proportion of subjects who achieved the target tacrolimus C0 on postoperative days 4 and 10 were significantly higher in the adapted group, 53.6% and 47.5%, compared to 24.3% and 17% in controls, respectively (P = 0.01). Adapted group subjects achieved their first target tacrolimus C0 significantly earlier (4 days) compared to 25 days in controls (P = 0.01). The total number of tacrolimus dose modifications required in the first postop month were lower in the adapted group; 47 compared to 68 in the controls (P = 0.05). The proportion of subjects with sub-therapeutic tacrolimus exposure on postoperative day 4 was significantly higher in the controls, 56% versus 10% in the adapted group (P < 0.001). There were no significant differences between the groups in the rate of biopsy proven acute rejections, adverse events, and graft function at the end of 3 months follow up.Conclusion:Genotype-based tacrolimus dosing leads to more subjects achieving the target tacrolimus C0 earlier. However, there may be a higher risk of tacrolimus nephrotoxicity.

A randomized crossover study comparing different tacrolimus formulations to reduce intrapatient variability in tacrolimus exposure in kidney transplant recipients.

A high intrapatient variability (IPV) in tacrolimus exposure is a risk factor for poor long‐term outcomes after kidney transplantation. The main objective of this trial was to investigate whether tacrolimus IPV decreases after switching patients from immediate‐release (IR)‐tacrolimus to either extended‐release (ER)‐tacrolimus or LifeCyclePharma (LCP)‐tacrolimus. In this randomized, prospective, open‐label, cross‐over trial, adult kidney transplant recipients on a stable immunosuppressive regimen, including IR‐tacrolimus, were randomized for conversion to ER‐tacrolimus or LCP‐tacrolimus, and for the order in which IR‐tacrolimus and the once‐daily formulations were taken. Patients were followed 6 months for each formulation, with monthly tacrolimus predose concentration assessments to calculate the IPV. The IPV was defined as the coefficient of variation (%) of dose corrected predose concentrations. Ninety‐two patients were included for analysis of the primary outcome. No significant differences between the IPV of IR‐tacrolimus (16.6%) and the combined once‐daily formulations (18.3%) were observed (% difference +1.7%, 95% confidence interval [CI] −1.1% to ‒4.5%, p = 0.24). The IPV of LCP‐tacrolimus (20.1%) was not significantly different from the IPV of ER‐tacrolimus (16.5%, % difference +3.6%, 95% CI −0.1% to 7.3%, p = 0.06). In conclusion, the IPV did not decrease after switching from IR‐tacrolimus to either ER‐tacrolimus or LCP‐tacrolimus. These results provide no arguments to switch kidney transplant recipients from twice‐daily (IR) tacrolimus formulations to once‐daily (modified‐release) tacrolimus formulations when the aim is to lower the IPV.

On the usefulness of four in vitro methodologies in screening for product related differences in tacrolimus exposure after oral administration of amorphous solid dispersions with modified release characteristics in the fasted state

ObjectiveTo investigate the usefulness of four in vitro methodologies in screening for product related differences in tacrolimus exposure after oral administration of amorphous solid dispersions with modified release characteristics in the fasted state. MethodsInitially, Advagraf® (5 mg tacrolimus/capsule), Envarsus® (4 mg tacrolimus/tablet) and a modified release Test Tablet (5 mg tacrolimus/tablet) were subjected to in vitro biorelevant performance testing simulating fasted state conditions using a small-scale two-stage biphasic system, a small-scale two-stage dissolution – permeation (D-P) system, the compendial apparatus IV (open loop mode) and the biorelevant gastrointestinal transfer (BioGIT) system. Early and total exposure, after single dose administrations of the three products to twelve healthy adults in the fasted state on a crossover basis, were then evaluated. Subsequently, the usefulness of in vitro data in qualitatively predicting product related differences in early exposure and in total exposure were assessed. ResultsProduct related differences in tacrolimus early exposure were successfully predicted by data collected with compendial apparatus IV. The two-stage biphasic system was useful for predicting differences in early exposure between the non-disintegrating Envarsus® and the disintegrating products (Advagraf® or Test Tablet). BioGIT data were useful only for discussing clinical data early after administration of the two disintegrating products. Prediction of product related differences in total exposure was successful only when the compendial apparatus IV was used for comparing the two disintegrating products. ConclusionsBiorelevant in vitro performance testing with compendial apparatus IV was useful for qualitatively predicting differences in tacrolimus early and total exposure after administration of disintegrating products with modified release characteristics in the fasted state.

Reduced calcineurin inhibitor exposure with antibody induction and recurrent hepatocellular carcinoma after liver transplantation

Background Hepatocellular carcinoma (HCC) is a common indication for liver transplantation (LT), but post-LT tumor recurrence remains a concern. Early post-LT immunosuppression is suggested to affect recurrence risk. We evaluated the impact on HCC recurrence of an immunosuppression protocol introduced in 2010 with interleukin-2 receptor antibody (IL-2RA) induction and delayed-introduction of reduced-dose tacrolimus with mycophenolate. Methods We included consecutive HCC patients transplanted 2000–2017 in Gothenburg. The impact on HCC recurrence of IL-2RA induction and mean tacrolimus trough concentration during the first 20 post-LT days was analyzed by multivariable Cox regression and propensity score-adjusted analyses. Results The study comprised 235 patients (mean age 57 yrs, men 80%, mean MELD 13, within Milan criteria 57%). The cumulative 5-yr HCC recurrence rate among patients transplanted before and after 2010 were 28.6% and 19.7%, respectively. IL-2RA induction had no independent effect on HCC recurrence. High tacrolimus exposure (mean 20-day tacrolimus concentration ≥8ng/mL) was associated with increased HCC recurrence risk on univariable analysis (HR 2.22, 95% CI 1.23–4.01, p = .008), but was non-significant on multivariable analysis (p = .17). Outside Milan criteria, high tacrolimus exposure was significant for HCC recurrence (HR 3.68, 95% CI 1.34–10.11, p = .012) independently of tumor characteristics and AFP level. This was confirmed on multivariable propensity score-adjusted analysis. Conclusions Reduced early tacrolimus exposure, facilitated by IL-2RA induction, was associated with reduced risk for HCC recurrence among patients outside Milan criteria. Prospective studies are needed to confirm if early tacrolimus-minimization strategies can help reduce HCC recurrence rates and help extend transplant criteria.

Limited sampling strategies for estimation of tacrolimus exposure in kidney transplant recipients receiving extended-release tacrolimus preparation.

Tacrolimus is the key component of most contemporary immunosuppressive drug regimens for the prevention of transplant rejection. Area under the concentration time curve over 24 h (AUC0–24) predicts efficacy, but predose (trough) tacrolimus blood concentration (C0) is currently used to guide dosing. In clinical or research situations where an estimate of AUC is required, collection of a full 24 h pharmacokinetic (PK) profile is cumbersome. Limited sampling strategies (LSSs) have been developed for some tacrolimus preparations but not for the new, extended‐release, once‐daily formulation of tacrolimus, ENVARSUS XR. Twenty‐four kidney transplant recipients were enrolled in this study. Twenty‐four tacrolimus PK profiles were obtained over 24 h. Multiple linear regression was used to generate LSSs with the best subset selection for accurate estimation of tacrolimus AUC0–24. The predictive performance of each model was assessed in the evaluation group. The correlation between actual and predicted AUC0–24 was evaluated and mean percentage prediction error (MPE%), mean absolute percentage prediction error (MAE%), and root mean squared error (RMSE) were calculated for each prediction model to assess bias and precision. The selected LSSs were highly correlated to AUC0–24 compared with the correlation between C0 and AUC0‐24. Two and three sampling points limited sampling strategies: C0, C2, and C10 provide the most reliable and effective LSS for estimation of tacrolimus AUC0–24 in routine clinic use. These limited sampling models can be applied in therapeutic drug monitoring schemes to personalize tacrolimus dosing for kidney transplant recipients on treatment with extended‐release tacrolimus.

Genetic Polymorphisms Affecting Tacrolimus Metabolism and the Relationship to Post-Transplant Outcomes in Kidney Transplant Recipients.

BackgroundTacrolimus is a key drug in kidney transplantation with a narrow therapeutic index. However, whether tacrolimus exposure variability affects clinical outcomes and adverse reactions remains unknown.ObjectiveOur study investigated the factors that influence tacrolimus exposure in kidney transplantation recipients and the relationship between tacrolimus concentration and clinical outcomes and adverse reactions.Settings and MethodsWe examined the effect of tacrolimus concentration on clinical outcomes and adverse reactions in 201 kidney transplantation recipients, and identified clinical and pharmacogenetic factors that explain tacrolimus exposure.ResultsThe CYP3A5 genotype was clearly associated with dose-adjusted trough blood tacrolimus concentrations (C0/D), whereas no significant difference was observed in patients with the CYP3A4*1B, CYP3A4*22, ABCB1, ABCC2, POR*28 or PXR alleles. Clinical factors such as red blood cell count, hemoglobin, and albumin were the most useful influence factors affecting tacrolimus C0/D. Besides, Wuzhi capsule increased tacrolimus C0/D in kidney transplantation recipients. Furthermore, higher tacrolimus concentrations were associated with higher diarrhea and post-transplant diabetes mellitus (PTDM) risk but not with acute rejection and chronic allograft kidney dysfunction.ConclusionClinical factors, medication, and CYP-enzyme polymorphisms accounted for tacrolimus concentration variability in kidney transplantation recipients. Furthermore, higher tacrolimus concentrations were associated with higher diarrhea and PTDM risk.

High Intrapatient Variability in Tacrolimus Exposure Calculated Over a Long Period Is Associated With De Novo Donor-Specific Antibody Development and/or Late Rejection in Thai Kidney Transplant Patients Receiving Concomitant CYP3A4/5 Inhibitors.

High intrapatient variability in tacrolimus trough levels (Tac IPV) is associated with poor allograft outcomes. Tac IPV was previously calculated using trough levels 6-12 months after kidney transplantation (KT). Data on the accuracy of Tac IPV calculation over a longer period, the association between high Tac IPV and donor-specific antibody (DSA) development after KT in Asian patients, and the role of IPV in patients receiving concomitant cytochrome P450 (CYP)3A4/5 inhibitors (CYPinh) are limited. A retrospective review of patients who underwent KT at our center in 2005-2015, and who received Tac with mycophenolate during the first 2 years after KT was performed. IPV was calculated using Tac levels adjusted by dosage. DSA was monitored annually after KT using a Luminex microbead assay. In total, 236 patients were enrolled. CYPinh were prescribed to 189 patients (80.1%): 145 (61.4%), 31 (13.1%), and 13 (5.5%) received diltiazem, fluconazole, and ketoconazole, respectively. Mean IPV calculated from adjusted Tac levels for 6-12 months (IPV6-12) and 6-24 months (IPV6-24) after KT were 20.64% ± 11.68% and 23.53% ± 10.39%, respectively. Twenty-six patients (11%) showed late rejection and/or DSA occurrence, and had significantly higher IPV6-24 (29.42% ± 13.78%) than others (22.77% ± 9.64%; P = 0.02). There was no difference in IPV6-12 (24.31% ± 14.98% versus 20.17% ± 10.90%; P = 0.18). IPV6-12 and IPV6-24 were comparable in patients who did and did not receive CYPinh. When using mean IPV6-24 as a cutoff, patients with higher IPV6-24 had a higher probability of developing DSA and/or late rejection (P = 0.048). Tac IPV6-24 was higher and more significantly associated with DSA development and/or late rejection than Tac IPV6-12, independent of Tac trough level. This is the first study to demonstrate the impact of high IPV on DSA development in Asian patients, and that Tac IPV is comparable between patients with and without CYPinh.

Impact of Pharmacogenetics on Intravenous Tacrolimus Exposure and Conversions to Oral Therapy

CYP3A5 and CYP3A4 are the predominant enzymes responsible for tacrolimus metabolism; however only a proportion of the population expresses CYP3A5 secondary to genetic variation. CYP3A5 is expressed in both the intestine and the liver and has been shown to impact both the bioavailability and metabolism of orally administered tacrolimus. Increasing the initial tacrolimus dose by 50% to 100% is recommended in patients who are known CYP3A5 expressers; however, whether this dose adjustment is appropriate for i.v. tacrolimus administration is unclear. The objective of this study was to evaluate the impact of CYP3A5 genotype as well as other pharmacogenes on i.v. tacrolimus exposure to determine whether the current genotype-guided dosing recommendations are appropriate for this formulation. In addition, this study aimed to investigate dose conversion requirements among CYP3A5 genotypes when converting from i.v. to p.o. tacrolimus. This study is a retrospective chart review of all patients who underwent allogeneic stem cell transplantation at Michigan Medicine between June 1, 2014, and March 1, 2018, who received i.v. tacrolimus at the time of their transplantation. Secondary use samples were obtained for genotyping CYP3A5, CYP3A4, and ABCB1. Patient demographic information, tacrolimus dosing and trough levels, and concomitant medications received at the time of tacrolimus trough were collected retrospectively from the patients' medical records. The i.v. dose-controlled concentration (C/D) and the i.v.:p.o. exposure ratio was calculated for all tacrolimus doses and patients, respectively. The impact of CYP3A5, CYP3A4, and ABCB1 genotypes on the i.v. C/D were evaluated with linear mixed modeling. The impact of CYP3A5 genotype on the i.v.:p.o. ratio was evaluated while controlling for age and concomitant use of an azole inhibitor. CYP3A5 and CYP3A4 genotypes were significantly associated with the i.v. C/D, with CYP3A5 expressers and CYP3A4 rapid metabolizers having 20% lower tacrolimus exposure. Neither genotype remained significant in the multivariable model, although age, hematocrit, and concomitant use of strong azole inhibitors were associated with increased i.v. C/D. When controlling for patient age and sex, CYP3A5 expressers had significantly higher i.v.:p.o. ratios than CYP3A5 nonexpressers (3.42 versus 2.78; P=.04). Post hoc analysis showed that the i.v.:p.o. ratio may differ among different CYP3A5 genotypes and azole inhibitor combinations. This study demonstrates that the current genotype-guided tacrolimus dose adjustment recommendations are inappropriate for CYP3A5 expressers receiving i.v. tacrolimus. Although CYP3A5 genotype is likely a minor contributor to i.v. tacrolimus exposure, genotype, in addition to capturing concomitant CYP3A inhibitors, would likely improve i.v.:p.o. dose conversion selection. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Tacrolimus Pharmacogenetics and Steady State Drug Concentrations in Cancer Patients Undergoing Allogeneic Stem Cell Transplantation

Background: Tacrolimus is the backbone of immunosuppressive therapy in patients undergoing an allogeneic stem cell transplant (SCT). Significant inter-patient variability in tacrolimus exposure exists, partly due to variations in pharmacokinetic genes. In particular, the Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines provide dosing recommendations based on CYP3A5 genotype; however, these are based on studies performed in patients undergoing solid organ transplants and receiving oral tacrolimus. We aimed to investigate the impact of CYP3A4, CYP3A5, and ABCB1 polymorphisms on intravenous (IV) tacrolimus exposure in allogeneic SCT patients.Methods: Buccal swabs were collected from allogeneic SCT patients on the day of admission (prior to transplant) between 07/03/14 and 06/22/2017. DNA was extracted using the GenElute™ Mammalian Genomic DNA Kit. A custom Ion AmpliSeq™ PGx Panel was used to genotype the samples for polymorphisms in CYP3A5 (*3, *6, *7), CYP3A4 (*1B, *22) and ABCB1 (C1236T, G2677T, C3435T), and the corresponding phenotypes were inferred based on available guidelines and literature. IV tacrolimus infusion was started at 0.03 mg/kg on day +5 post-transplant. Blood samples were drawn every 2 days, and doses were adjusted after reaching steady-state (SS), targeting a plasma concentration of 5-15 ng/mL. The primary endpoint was the prevalence of non-therapeutic concentrations at SS (4th day after starting tacrolimus) between phenotypes, which was compared using the Fisher's exact test. Univariate and multivariable logistic regression analyses were performed to explore demographic variables and gene phenotypes associated with prevalence of non-therapeutic SS concentrations. Student's t-test was used to compare mean tacrolimus SS concentration between phenotypes.Results: The study included 63 adult patients with a mean age of 54 (range 25-78) years. The majority were male (65%), 73% were Caucasian and 22% were African American. The inferred phenotype frequencies for CYP3A5, CYP3A4 and ABCB1 are shown in Table 1. No patient (0%) had an initial sub-therapeutic tacrolimus SS concentration (< 5 ng/mL), whereas 28.6% (n=18) and 71.4% (n=45) had an initial therapeutic and supra-therapeutic tacrolimus SS concentration (> 15 ng/mL), respectively. The prevalence of supra-therapeutic tacrolimus SS concentration was 80% in CYP3A4 NM/IMs and 43% among CYP3A4 RMs (p=0.016). Approximately 87% of carriers of at least one copy of the loss of function allele for ABCB1 C2677T (2677 CT and 2677 TT) had a supra-therapeutic tacrolimus SS concentration compared to 50% in non-carriers (2677 CC, p=0.004). Alternatively, there were no significant differences in the prevalence of supra-therapeutic SS concentrations by CYP3A5, ABCB1 C1236T, and ABCB1 C3435T genotypes (p>0.05). Univariate logistic regression analysis identified Caucasian race (p=0.009), CYP3A4 (p=0.011), and ABCB1 C2677T (p=0.003) as significantly associated with supra-therapeutic SS concentrations (Table 2). Of these, only ABCB1 C2677T was retained in the multivariable model (p=0.004). The mean tacrolimus SS concentration in CYP3A4 IM/NMs and RMs were 16.9 ± 4.5 ng/mL and 14.2 ± 3.9 ng/mL, respectively (p=0.048). Carriers of the T allele for ABCB1 C2677T (2677 CT and 2677 TT) had a significantly higher mean tacrolimus SS concentration compared to non-carriers (17.5 ± 4.3 ng/mL vs. 14.6 ± 4.2 ng/mL, p=0.009). There was no significant difference in the mean tacrolimus SS concentration based on CYP3A5, ABCB1 C1236T and ABCB1 C3435T polymorphisms (p>0.05).Conclusion:ABCB1 C2677T and CYP3A4 appear to be important determinants of tacrolimus exposure after IV administration in adult patients receiving an allogeneic SCT. Our results did not demonstrate an association between CYP3A5 genotype and tacrolimus concentration, possibly due to IV administration and differential expression of CYP3A5 (higher in the gut resulting in first-pass metabolism). Further studies are necessary to validate these findings on a larger scale and to evaluate genotype-guided dose selection to optimize tacrolimus exposure. Future guidelines should discuss potential differences in pharmacogenetics findings between oral and IV tacrolimus and different populations (SCT vs. solid organ transplant). [Display omitted] DisclosuresTrivedi:Pharmacyclics: Consultancy, Honoraria. Grunwald:Alexion: Consultancy; Incyte: Consultancy, Research Funding; Celgene: Consultancy; ARIAD: Consultancy; Cardinal Health: Consultancy; Amgen: Consultancy, Research Funding; Pfizer: Consultancy; Forma Therapeutics: Research Funding; Janssen: Research Funding; Genentech: Research Funding. Ghosh:Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Jassen: Consultancy, Honoraria, Research Funding; Kite Pharma: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; TG Therapeutics: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Speakers Bureau; AbbVie: Consultancy, Honoraria, Speakers Bureau; Pharmacyclics: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Acute Kidney Injury before Day 90 Predicts for Both Early and Late Mortality after FluBu4

Acute kidney injury (AKI) is a frequent complication after hematopoietic stem cell transplantation (HSCT). Prior studies have shown a negative impact on survival when AKI develops early after HSCT, but have primarily included patients receiving regimens associated with a high degree of toxicity, in particular total body irradiation based-regimens. Fludarabine/ i.v. busulfan (FluBu4) is a myeloablative regimen with reduced extra-hematologic toxicity. We sought to examine the impact of AKI on survival in patients receiving FluBu4.We retrospectively analyzed 91 consecutive adult patients who underwent allogeneic stem cell transplant and conditioning with FluBu4 between January 2003 and December 2016. The FluBu4 regimen consisted of daily fludarabine 40 mg/m2 and i.v. busulfan (AUC of 4800 mmol-min per dose) over 4 days. All patients received GVHD prophylaxis with tacrolimus and methotrexate. We observed a high incidence of AKI (defined as creatinine clearance below 60 ml/min) within 90 days of HSCT (n=62, 68%). The mean of the lowest measured creatinine clearance was 39.4 ml/min (± 14.2) in the AKI group and 81.7 ml/min (± 16.26) in the non-AKI group (p<0.0001). Baseline characteristics including disease risk index (DRI) and hematopoietic cell transplant-comorbidity index (HCT-CI) were similar between the two groups. However, patients in the AKI group were older (48.5 versus 29 years, p<0.0001). The mean tacrolimus concentration in the first 90 days after HSCT was similar between the two groups (9.2 versus 9.1 ng/mL, p=0.87).In our cohort, we found that the median time to neutrophil (16 versus 15 days, p=0.5) and platelet (16 versus 16 days, p=0.16) engraftment was similar between the AKI and non-AKI group. Patients that experienced AKI within the first 90 days of HSCT had significantly worse overall survival (OS) (26.3 months versus median not reached, p=0.04) and progression-free survival (PFS) (19.6 months versus median not reached, p=0.02). When patients who died within the first 90 days were excluded and survival was measured from Day 90, AKI still predicted for poor OS (46.8 months versus not reached, p=0.03) and PFS (43.2 months versus not reached, p=0.02). The incidence of grade III-IV acute graft-versus-host disease was similar between the two groups. However, patients who developed AKI had a significantly higher cumulative incidence of relapse (21 (34%) versus 4 (14%), p=0.03) making this the major driver of reduced OS and PFS. In an age-adjusted multivariate analysis, AKI was associated with significant decreases in both OS (p=0.047) and PFS (p=0.033).We next analyzed the impact of early AKI on the development of chronic kidney disease (CKD) at one year. In all patients surviving more than one year, we found that 13 (34%) of 38 patients in the AKI group and 1 (4.5%) of 22 patients in the non-AKI group developed CKD (p=0.02). OS measured from 1 year post transplant was significantly shorter in patients with CKD (39.3 months versus median not reached, p=0.002).This is the first study evaluating the impact of AKI on outcomes in patients undergoing HSCT with FluBu4. We observed a high incidence of AKI during the first 90 days that predicted for worse OS and PFS. We hypothesize that the significantly higher relapse rate observed in the AKI group is due to increased tacrolimus exposure and diminished graft-versus-leukemia effect. Although mean tacrolimus levels were comparable between groups, these measurements are likely not an accurate estimation of cumulative tacrolimus exposure. Finally, early AKI also leads to a significant increase in CKD at one year, which in our cohort is associated with late mortality after HSCT. DisclosuresPatel:Celgene: Consultancy, Honoraria.

Rationale and design of the OPTIMIZE trial: OPen label multicenter randomized trial comparing standard IMmunosuppression with tacrolimus and mycophenolate mofetil with a low exposure tacrolimus regimen In combination with everolimus in de novo renal transplantation in Elderly patients

BackgroundIn 2019, more than 30 % of all newly transplanted kidney transplant recipients in The Netherlands were above 65 years of age. Elderly patients are less prone to rejection, and death censored graft loss is less frequent compared to younger recipients. Elderly recipients do have increased rates of malignancy and infection-related mortality. Poor kidney transplant function in elderly recipients may be related to both pre-existing (i.e. donor-derived) kidney damage and increased susceptibility to nephrotoxicity of calcineurin inhibitors (CNIs) in kidneys from older donors. Hence, it is pivotal to shift the focus from prevention of rejection to preservation of graft function and prevention of over-immunosuppression in the elderly. The OPTIMIZE study will test the hypothesis that reduced CNI exposure in combination with everolimus will lead to better kidney transplant function, a reduced incidence of complications and improved health-related quality of life for kidney transplant recipients aged 65 years and older, compared to standard immunosuppression.MethodsThis open label, randomized, multicenter clinical trial will include 374 elderly kidney transplant recipients (≥ 65 years) and consists of two strata. Stratum A includes elderly recipients of a kidney from an elderly deceased donor and stratum B includes elderly recipients of a kidney from a living donor or from a deceased donor < 65 years. In each stratum, subjects will be randomized to a standard, tacrolimus-based immunosuppressive regimen with mycophenolate mofetil and glucocorticoids or an adapted immunosuppressive regimen with reduced CNI exposure in combination with everolimus and glucocorticoids. The primary endpoint is ‘successful transplantation’, defined as survival with a functioning graft and an eGFR ≥ 30 ml/min per 1.73 m2 in stratum A and ≥ 45 ml/min per 1.73 m2 in stratum B, after 2 years, respectively.ConclusionsThe OPTIMIZE study will help to determine the optimal immunosuppressive regimen after kidney transplantation for elderly patients and the cost-effectiveness of this regimen. It will also provide deeper insight into immunosenescence and both subjective and objective outcomes after kidney transplantation in elderly recipients.Trial registrationClinicalTrials.gov: NCT03797196, registered January 9th, 2019. EudraCT: 2018-003194-10, registered March 19th, 2019.

Tacrolimus variability score outperforms coefficient of variation in predicting clinical outcomes of living kidney transplantation.

Intrapatient variability (IPV) was previously defined as coefficient of variation (CV) or standard deviation of tacrolimus (Tac) exposure while none of them was easily being interpreted and translated into clinical practice after kidney transplantation. We developed a novel Tac variability score (TVS) to evaluate IPV by calculating the frequency of clinically significant changes of Tac trough levels after kidney transplantation. Multivariate Cox proportional analyses were conducted to compare the impact of TVS and CV on transplant outcomes. A total of 1343 patients were divided into high TVS (>0.30) and low TVS (<0.30) groups, and low CV (<0.30) and high CV (>0.30) groups. Univariate analyses showed that high TVS (hazard ratio [HR]: 2.323, 95% confidence interval [CI]: 1.455-3.709) and high CV (HR: 1.606, 95%CI: 1.044-2.471) were associated with inferior graft survival. However, only TVS was an independent predictor for graft failure in multivariate analyses (HR: 1.972, 95%CI: 1.2-3.24), and the correlation maintained in high CV (P =.020) and low CV (P =.037) subgroups, while CV failed to predict graft loss in neither low (P =.387) nor high TVS (P =.600) subgroups. In addition, TVS had a higher correlation with graft survival in patients with Tac exposure within the therapeutic range and the correlation was less influenced by mean Tac trough levels. TVS is a novel measure of Tac IPV with higher correlation with graft survival and more convenience in clinical use than CV after kidney transplantation.

Interaction of tacrolimus through hedgehog signaling pathway: An in vitro evaluation using rat hepatocytes.

Tacrolimus (TAC) is the drug of choice in immunosuppressive therapy for organ transplantation; however, adverse effects are still a major concern. The current study aims to decipher the short-term exposure of TAC on rat hepatocytes in relation to activation of hedgehog (HH) signaling pathway. Time dependent study was conducted using primary rat hepatocytes treated with TAC (36 µM) for 6, 12, 24 and 48 h. Western blot analysis was performed using cell lysate in order to analyze the regulation of HH pathway proteins including HHIP, SMO, PTCH, IHH, SHH, and GLI transcription factors. The study revealed change in protein expression of HH signaling molecules with activation of HH pathway, due to downregulation of HHIP, and enrichment of HH ligands with activation of SMO and GLI transcription factors. It is therefore, concluded that short term TAC exposure leads to upregulation of HH pathway in liver, which may initially act to repair the liver damage but can worsen the condition in case of prolonged immunosuppressive therapy. This insight could lead to understand association of off target effects of immunosuppressive drugs and occurrence of other liver diseases in transplant patients when it comes to long term immunosuppressive therapy. These findings also illuminate a novel direction that use of HH inhibitor might provide a therapeutic strategy for immune suppression related liver disorders.

Impact of Clotrimazole Fungal Prophylaxis on Tacrolimus Exposure in Kidney Transplant Recipients: A Retrospective Study

Tacrolimus, an immunosuppressant prescribed to reduce the risk of organ rejection, is metabolized by cytochrome P450 and is a substrate for P-glycoprotein. Many medications affect tacrolimus concentrations, making it difficult to maintain exposure within its narrow therapeutic index. Clotrimazole troches, prescribed to posttransplant recipients immediately for the first 30 days for oral candidiasis prevention, are considered nonsystemic. However, data suggest a potential drug interaction, affecting tacrolimus exposure.To assess the magnitude of the effect of clotrimazole on tacrolimus trough levels, 97 kidney transplant recipients, on a stable dose of tacrolimus, were retrospectively evaluated. Tacrolimus trough concentrations were analyzed 7 and 14 days before and after discontinuation of clotrimazole. The median change in tacrolimus trough level was -1.3 ng/mL (confidence interval, -2.5, -1.0; P < .001) at day 7 and -2.8 ng/mL (confidence interval, -3.3, -1.6; P < .001) at day 14 after clotrimazole discontinuation, from a median baseline of 8.9 ng/mL. Overall, a reduction in tacrolimus level was observed in 60% of patients after discontinuation of clotrimazole. When assessing the effect of race and sex, no influence was found on the degree of change in tacrolimus level after clotrimazole discontinuation. In conclusion, clotrimazole exerts a significant interaction on tacrolimus where close monitoring of tacrolimus trough levels after discontinuation of clotrimazole is warranted.