Gender differences in pharmacokinetics of tacrolimus and their clinical significance in kidney transplant recipients

Recipient-Donor Sex Constellation in Liver Transplantation for Hepatocellular Carcinoma-An ELTR Study

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Liver transplantation (LT) is a curative treatment option. We investigated survival outcomes based on recipient-donor sex constellation (RDSC) following LT.

METHODS

We performed a European Liver Transplant Registry analysis, including patients from 1988 to December 2022. The cohort was split into four RDSC groups: female donor female recipient (FDFR), female donor male recipient (FDMR), male donor female recipient (MDFR) and male donor male recipient (MDMR). Survival analysis, including death with recurrence, was performed.

RESULTS

In 7601 LT for HCC with an overall median follow-up of 22.6 months (5.8, 60.7), death was registered in 25.1% and, as primary cause of death, HCC tumour recurrence in 26.0%. There was no statistically significant difference on crude survival estimates among the different RDSC groups (log-rank p = 0.66) with 10-year overall survival (OS) of 54.5% in FDFR, 54.6% in FDMR, 59.1% in MDFR and 56.9% in MDMR. On multivariable analysis, RDSC showed a significant effect on OS (FDFR as reference): MDFR (aHR 0.72, p = 0.023). No significant difference was found for FDMR (aHR 0.98, p = 0.821) and MDMR (aHR 0.90, p= 0.288). Regarding overall registered causes of death, differences between RDSC groups were found in rejection (p = 0.017) and cardiovascular (p = 0.046) associated deaths.

CONCLUSIONS

In female recipients undergoing LT for HCC, male donor grafts were associated with a 28% reduction of mortality compared to female donor grafts.

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.

Women's health and kidney protective medications

PURPOSE OF REVIEW

We discuss the sex-based differences in the pharmacokinetics and pharmacodynamics of kidney protective medications and their implications on women's health.

RECENT FINDINGS

A critical examination of adverse drug reactions highlights the underrepresentation of women in clinical trials for kidney and cardiovascular protective drugs, such as SGLT2 inhibitors, ACE inhibitors, and endothelin receptor antagonists. This underscores the need for sex-specific analyses in clinical studies to accurately assess medication efficacy and safety.

SUMMARY

The research demonstrates that women are more likely to experience adverse events and less likely to benefit from certain treatments, emphasizing the urgent need for healthcare providers to adopt a sex-informed approach in prescribing practices. Future research should prioritize sex differences from the outset to enhance understanding and improve clinical outcomes for women with chronic kidney disease and cardiovascular conditions.

[Sex differences in hepatobiliary and transplantation surgery]

Gender-specific differences in hepatobiliary and transplantation surgery are decisive for the diagnosis, treatment and long-term outcomes. Men exhibit a higher risk of late recurrences and cancer-specific death after liver cancer resection. The emphasis on screening recommendations and ensuring equal access to treatment options are vital to minimize disparities. In kidney and liver transplantations, women are less frequently listed and endure longer waiting times, while men dominate the waiting list. Gender-specific disparities in drug compatibility necessitate differentiated dosing. Further studies are needed to ensure equity in transplantation treatment. Individualized treatment considering these differences can enhance treatment outcomes and the quality of life of patients.

Recipient donor sex combinations in solid organ transplantation and impact on clinical outcome: A scoping review

INTRODUCTION

Solid organ transplantation (SOT) is a lifesaving treatment for end-stage organ failure. Although many factors affect the success of organ transplantation, recipient and donor sex are important biological factors influencing transplant outcome. However, the impact of the four possible recipient and donor sex combinations (RDSC) on transplant outcome remains largely unclear.

METHODS

A scoping review was carried out focusing on studies examining the association between RDSC and outcomes (mortality, graft rejection, and infection) after heart, lung, liver, and kidney transplantation. All studies up to February 2023 were included.

RESULTS

Multiple studies published between 1998 and 2022 show that RDSC is an important factor affecting the outcome after organ transplantation. Male recipients of SOT have a higher risk of mortality and graft failure than female recipients. Differences regarding the causes of death are observed. Female recipients on the other hand are more susceptible to infections after SOT.

CONCLUSION

Differences in underlying illnesses as well as age, immunosuppressive therapy and underlying biological mechanisms among male and female SOT recipients affect the post-transplant outcome. However, the precise mechanisms influencing the interaction between RDSC and post-transplant outcome remain largely unclear. A better understanding of how to identify and modulate these factors may improve outcome, which is particularly important in light of the worldwide organ shortage. An analysis for differences of etiology and causes of graft loss or mortality, respectively, is warranted across the RDSC groups.

PRACTITIONER POINTS

Recipient and donor sex combinations affect outcome after solid organ transplantation. While female recipients are more susceptible to infections after solid organ transplantation, they have higher overall survival following SOT, with causes of death differing from male recipients. Sex-differences should be taken into account in the post-transplant management.

Improved LC-MS/MS method for the simultaneous quantification of tacrolimus and cyclosporine A in human blood and application to therapeutic drug monitoring

In order to facilitate therapeutic drug monitoring of tacrolimus and cyclosporine A in clinical practice, a simple, rapid, robust, sensitive and specific LC-MS/MS assay was developed and validated for the simultaneous determination of tacrolimus and cyclosporine A in human whole blood. Erythrocytes were destroyed using internal standard solution with 10% (w/v) zinc sulfate in water. The analytes were extracted from 100 μl of whole blood by protein precipitation with acetonitrile. Chromatographic separation was conducted on a Kinetex PFP column (60°C) by a gradient elution with a flow rate of 0.450 ml/min in 2.5 min. Quantitative analysis was performed using electrospray ionization and multiple reaction monitoring in positive ionization mode. The method was fully validated as per current guidelines on bioanalytical methodologies of the US Food and Drug Administration and European Medicines Agency. The method developed was applied successfully in analyzing clinical samples from patients administered tacrolimus or cyclosporine A. The sample treatment procedure was rationalized and improved to fulfill the complete target extraction. The chromatography conditions were optimized to achieve rapid and accurate quantification of both analytes. This method may be beneficial as a constructive input for the therapeutic drug monitoring of tacrolimus and cyclosporine A in obtaining individualized therapy.

Dosage optimization of tacrolimus based on the glucocorticoid dose and pharmacogenetics in adult patients with systemic lupus erythematosus

BACKGROUND

The purpose of the study was to develop a genotype-incorporated population pharmacokinetic (PPK) model of tacrolimus (TAC) in adults with systemic lupus erythematosus (SLE) to investigate the factors influencing TAC pharmacokinetics and to develop an individualized dosing regimen based on the model. In addition, a non-genotype-incorporated model was also established to assess its predictive performance compared to the genotype-incorporated model.

METHODS

A total of 365 trough concentrations from 133 adult SLE patients treated with TAC were collected to develop a genotype-incorporated PPK model and a non-genotype-incorporated PPK model of TAC using a nonlinear mixed-effects model (NONMEM). External validation of the two models was performed using data from an additional 29 patients. Goodness-of-fit diagnostic plots, bootstrap method, and normalized predictive distribution error test were used to validate the predictive performance and stability of the final models. The goodness-of-fit of the two final models was compared using the Akaike information criterion (AIC). The dosing regimen was optimized using Monte Carlo simulations based on the developed optimal model.

RESULTS

The typical value of the apparent clearance (CL/F) of TAC estimated in the final genotype-incorporated model was 14.3 L h-1 with inter-individual variability of 27.6%. CYP3A5 polymorphism and coadministered medication were significant factors affecting TAC-CL/F. CYP3A5 rs776746 GG genotype carriers had only 77.3% of the TAC-CL/F of AA or AG genotype carriers. Omeprazole reduced TAC-CL/F by 3.7 L h-1 when combined with TAC, while TAC-CL/F increased nonlinearly as glucocorticoid dose increased. Similar findings were demonstrated in the non-genotype-incorporated PPK model. Comparing these two models, the genotype-incorporated PPK model was superior to the non-genotype-incorporated PPK model (AIC = 643.19 vs. 657.425). Monte Carlo simulation based on the genotype-incorporated PPK model indicated that CYP3A5 rs776746 AA or AG genotype carriers required a 1/2-1 fold higher dose of TAC than GG genotype carriers to achieve the target concentration. And as the daily dose of prednisone increases, the dose of TAC required to reach the target concentration increases appropriately.

CONCLUSIONS

We developed the first pharmacogenetic-based PPK model of TAC in adult patients with SLE and proposed a dosing regimen based on glucocorticoid dose and CYP3A5 genotype according to the model, which could facilitate individualized dosing for TAC.

Investigating Tacrolimus Disposition in Paediatric Patients with a Physiologically Based Pharmacokinetic Model Incorporating CYP3A4 Ontogeny, Mechanistic Absorption and Red Blood Cell Binding

Tacrolimus is a crucial immunosuppressant for organ transplant patients, requiring therapeutic drug monitoring due to its variable exposure after oral intake. Physiologically based pharmacokinetic (PBPK) modelling has provided insights into tacrolimus disposition in adults but has limited application in paediatrics. This study investigated age dependency in tacrolimus exposure at the levels of absorption, metabolism, and distribution. Based on the literature data, a PBPK model was developed to predict tacrolimus exposure in adults after intravenous and oral administration. This model was then extrapolated to the paediatric population, using a unique reference dataset of kidney transplant patients. Selecting adequate ontogeny profiles for hepatic and intestinal CYP3A4 appeared critical to using the model in children. The best model performance was achieved by using the Upreti ontogeny in both the liver and intestines. To mechanistically evaluate the impact of absorption on tacrolimus exposure, biorelevant in vitro solubility and dissolution data were obtained. A relatively fast and complete release of tacrolimus from its amorphous formulation was observed when mimicking adult or paediatric dissolution conditions (dose, fluid volume). In both the adult and paediatric PBPK models, the in vitro dissolution profiles could be adequately substituted by diffusion-layer-based dissolution modelling. At the level of distribution, sensitivity analysis suggested that differences in blood plasma partitioning of tacrolimus may contribute to the variability in exposure in paediatric patients.

Tacrolimus-why pharmacokinetics matter in the clinic

The calcineurin inhibitor (CNI) Tacrolimus (Tac) is the most prescribed immunosuppressant drug after solid organ transplantation. After renal transplantation (RTx) approximately 95% of recipients are discharged with a Tac-based immunosuppressive regime. Despite the high immunosuppressive efficacy, its adverse effects, narrow therapeutic window and high intra- and interpatient variability (IPV) in pharmacokinetics require therapeutic drug monitoring (TDM), which makes treatment with Tac a major challenge for physicians. The C/D ratio (full blood trough level normalized by daily dose) is able to classify patients receiving Tac into two major metabolism groups, which were significantly associated with the clinical outcomes of patients after renal or liver transplantation. Therefore, the C/D ratio is a simple but effective tool to identify patients at risk of an unfavorable outcome. This review highlights the challenges of Tac-based immunosuppressive therapy faced by transplant physicians in their daily routine, the underlying causes and pharmacokinetics (including genetics, interactions, and differences between available Tac formulations), and the latest data on potential solutions to optimize treatment of high-risk patients.

Advanced imaging techniques for tracking drug dynamics at the subcellular level

Optical microscopes are an important imaging tool that have effectively advanced the development of modern biomedicine. In recent years, super-resolution microscopy (SRM) has become one of the most popular techniques in the life sciences, especially in the field of living cell imaging. SRM has been used to solve many problems in basic biological research and has great potential in clinical application. In particular, the use of SRM to study drug delivery and kinetics at the subcellular level enables researchers to better study drugs' mechanisms of action and to assess the efficacy of their targets in vivo. The purpose of this paper is to review the recent advances in SRM and to highlight some of its applications in assessing subcellular drug dynamics.

Representation of Women in Contemporary Kidney Transplant Trials

Women are often underrepresented in clinical trials. It is unclear if this applies to trials in kidney transplant (KT) and whether the intervention or trial focus influences this. In this study, the weighted participation-to-prevalence ratio (PPR) for women enrollees in KT trials was determined for leading medical transplant or kidney journals between 2018 and 2023 using meta-regression overall and in three sensitivity analyses by: 1) Whether the intervention involved immunosuppression; 2) Area of trial focus; rejection, cardiometabolic, infection, lifestyle, surgical; 3) Whether the intervention was medical/surgical or social/behavioral. Overall, 33.7% of participants in 24 trials were women. The overall pooled PPR for the included trials was 0.80, 95% CI 0.76-0.85, with significant heterogeneity between trials (I 2 56.6%, p-value < 0.001). Women had a lower PPR when the trial involved immunosuppression (PPR 0.77, 95% CI 0.72-0.82) than when it did not (PPR 0.86, 95% CI 0.80-0.94) and were less likely to participate in trials with a medical/surgical versus behavioral intervention; the lowest PPR for women was in studies examining rejection risk (PPR 0.75, 95% CI 0.70-0.81). There is better representation of women in KT trials compared to other medical disciplines, however women remain underrepresented in transplant trials examining immunosuppression and rejection.

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.

Sex and Gender Differences in Kidney Transplantation

Sex and gender often are used interchangeably, but are two distinct entities, with sex being the biological attribute and gender including the social, psychological, and cultural aspects of one's identity. Kidney transplantation has been proven to be the best treatment for end-stage kidney disease, improving both quality of life and life-expectancy for most patients. However, gender disparities in access to and outcomes of kidney transplantation remain despite the plethora of evidence showing the advantages of kidney transplantation to our patients. Data have shown that women are less likely to be waitlisted for a kidney transplant and to receive a deceased donor or a living donor kidney. On the other hand, women are more likely than men to become living kidney donors. Although some state the latter is the result of the female gender to nurture and care for loved ones, others believe this observation is because women often are incompatible with their spouse or child because pregnancy is a strong sensitizing event, which stems from the biological rather than the social differences between the sexes. Influence of sex and gender is not limited to access to kidney transplantation, but rather exist in other areas of transplant medicine, such as the difference observed in transplant outcomes between the sexes, variability in immunosuppression metabolism, and even in more contemporary areas such as recent data showing sex-based differences in outcomes of kidney transplant recipients with coronavirus disease-2019, with males having an increased incidence of acute kidney injury and death.

Age- and sex-mediated differences in T lymphocyte populations of kidney transplant recipients

BACKGROUND

Graft failure rates increase through childhood and adolescence, decline in adulthood, and are higher in female than male kidney transplant recipients (KTR) until middle age. We aimed to describe age- and sex-related differences in T-cell subsets among KTR to determine which differences may help to explain the differences in kidney graft failure rates.

METHODS

Effector T (Teff)-cell and regulatory T (Treg)-cell phenotypes in PBMCs from healthy controls and KTR, who were at least 1 year post-transplant with stable graft function under immunosuppression, were analyzed by flow cytometry. The effects of age, sex, and status (KTR or control) were analyzed using linear regressions.

RESULTS

We enrolled 20 male and 21 female KTR and 20 male and 20 female controls between 3 and 29 years of age. CD3+ T-cell frequencies were not associated with age or sex but were higher in KTR than controls. There were no differences in CD4+ and CD8+ frequencies. Th1 (IFNγ+ IL-4- IL-17A-) and Th17 (IL-17A+) frequencies within the CD4+ T-cell population were higher at older ages. The frequencies of FOXP3 + Helios + Treg cells in CD4+ CD25+ CD127- T cells were lower in females than males and in KTR than controls.

CONCLUSIONS

Increasing frequencies of Th1 and Th17 cells with increasing age mirrors the increasing graft failure rates from childhood to young adulthood. Importantly, sex differences in frequencies of circulating Treg cells may suggest a role in the sex differences in graft failure rates.

Sex-tailored pharmacology and COVID-19: Next steps towards appropriateness and health equity

Making gender bias visible allows to fill the gaps in knowledge and understand health records and risks of women and men. The coronavirus disease 2019 (COVID-19) pandemic has shown a clear gender difference in health outcomes. The more severe symptoms and higher mortality in men as compared to women are likely due to sex and age differences in immune responses. Age-associated decline in sex steroid hormone levels may mediate proinflammatory reactions in older adults, thereby increasing their risk of adverse outcomes, whereas sex hormones and/or sex hormone receptor modulators may attenuate the inflammatory response and provide benefit to COVID-19 patients. While multiple pharmacological options including anticoagulants, glucocorticoids, antivirals, anti-inflammatory agents and traditional Chinese medicine preparations have been tested to treat COVID-19 patients with varied levels of evidence in terms of efficacy and safety, information on sex-targeted treatment strategies is currently limited. Women may have more benefit from COVID-19 vaccines than men, despite the occurrence of more frequent adverse effects, and long-term safety data with newly developed vectors are eagerly awaited. The prevalent inclusion of men in randomized clinical trials (RCTs) with subsequent extrapolation of results to women needs to be addressed, as reinforcing sex-neutral claims into COVID-19 research may insidiously lead to increased inequities in health care. The huge worldwide effort with over 3000 ongoing RCTs of pharmacological agents should focus on improving knowledge on sex, gender and age as pillars of individual variation in drug responses and enforce appropriateness.

Sex differences in cancer risk and outcomes after kidney transplantation

Kidney transplant recipients (KTRs) experience a two- to four-fold increased risk of developing and dying from cancer compared with the general population. High cancer risk results from the interaction of both modifiable and non-modifiable factors. This mapping review explores the impact of sex disparity on cancer's increased incidence and mortality after kidney transplantation (KT). In terms of age, population-based studies indicate that younger recipients of both sexes experience a higher risk of cancer, but this is more pronounced in young women. On the contrary, older men are more likely to be diagnosed with cancer, although their increased risk is not statistically significant compared with the general population. Regarding cancer type, studies show an increased risk of Kaposi sarcoma, gynecologic and lung cancer in women, and bladder and kidney cancer in men. Immune-related cancers such as pos-transplant lymphoproliferative disorders and melanoma are increased in both sexes. Mortality also shows differences between sexes. Although cancer is the second cause of death in both male and female KTRs, studies show higher overall mortality in men and elderly recipients. However, the relative risk of cancer mortality compared with the general population is higher at a younger age, with disparate results regarding sex. Female KTRs appear to die at a younger age than males when compared with the general population. Differences in cancer rates by sex after renal transplantation need further studies. A better understanding of sex-specific differences in cancer epidemiology after KT could help nephrologists to better address pre-transplant counseling, to establish early surveillance programs, and to plan modifiable risk factors such as immunosuppression.

Initial tacrolimus weight-based dosing strategy in allogeneic hematopoietic stem-cell transplantation

Tacrolimus is a mainstay medication for graft-versus-host disease (GVHD) prophylaxis in combination with other immunosuppressive agents. Achieving therapeutic tacrolimus levels is vital in preventing acute GVHD (aGVHD), while supratherapeutic levels may increase risk of toxicity and relapse. We performed a single center retrospective chart review including all adult patients post-allogeneic hematopoietic stem-cell transplantation who received initial tacrolimus continuous intravenous infusion for GVHD prophylaxis between June 1, 2017 and December 31, 2019. The primary outcome was the percent of patients with an initial therapeutic tacrolimus level, defined as 5-12 ng/mL, after empiric weight-based dosing at 0.02 mg/kg/day. Secondary outcomes included evidence of tacrolimus toxicity within seven days of initiation, incidence of aGVHD by day 100, and relapse after six months. An initial therapeutic level was achieved in 47% of patients with a median initial level of 12.4 ng/mL. Fifty-two percent of patients had supratherapeutic levels. No significant nephrotoxicity, hepatotoxicity, or neurotoxicity occurred within a week of starting tacrolimus or at neutrophil engraftment. Grade II-IV aGVHD by day 100 was observed in 22% of patients, and relapse after six months was found in 16% of patients. These results have led to consideration of an empiric 20% dose reduction to 0.016 mg/kg/day or an expanded initial tacrolimus target of 5-15 ng/mL as there was low aGVHD incidence and no increased risk of toxicity.

Tacrolimus: Influence of the Posttransplant Concentration/Dose Ratio on Kidney Graft Function in a Two-Year Follow-Up

INTRODUCTION

Tacrolimus (TAC) metabolism rate has the potential to impact graft function after kidney transplantation (KTx). We aimed to analyze the relationship between the early post-KTx TAC C/D ratio (blood trough concentration normalized by total daily dose) and kidney graft function in a 2-year follow-up.

METHODS

We retrospectively analyzed data from 101 post-KTx patients at 3, 6, 12, and 24 months after KTx to identify the C/D ratio cutoff value optimal for dividing patients into fast and slow TAC metabolizers. We investigated the relationship between their TAC metabolism rate and graft function.

RESULTS

Patients were divided based on the TAC C/D ratio at 6 months after KTx of 1.47 ng/mL * 1 mg. Fast metabolizers (C/D ratio <1.47 ng/mL * 1 mg) presented with significantly worse graft function throughout the whole study period (p < 0.05 at each timepoint) and were significantly less likely to develop good graft function (estimated glomerular filtration rate ≥45 mL/min/1.73 m2) than slow metabolizers. Our model based on donor and recipient age, recipient sex and slow/fast metabolism status allowed for identification of patients with compromised graft function in 2-year follow-up with 66.7% sensitivity and 94.6% specificity.

CONCLUSION

Estimating TAC C/D ratio at 6 months post-KTx might help identify patients at risk of developing deteriorated graft function in a 2-year follow-up.

Adverse effects of mycophenolic acid in renal transplant recipients: gender differences

Background Mycophenolic acid is widely used immunosuppressive drug, associated with adverse effects which increase patient morbidity and decrease medication adherence. Objective To evaluate the adverse effects in renal transplant recipients under mycophenolate treatment with respect to gender. Setting University Clinical Centre of Nis, Clinic of Nephrology, Serbia. Method This research included 96 renal transplant recipients, who received immunosuppressive regimen, based on tacrolimus or cyclosporin A, prednisone and mycophenolic acid. The high-performance liquid chromatography method combined with protein precipitation was used for the analysis of mycophelate concentration in human plasma. Drug concentration and dose-adjusted concentration were determined with respect to the patients' gender. An adverse effect scoring system developed by nephrologists within the University of Buffalo Nephrology/Transplant Program was used to monitor adverse effects of therapy. Main outcome measure Individual and scores of adverse effects in relation to the dosing regimen and gender. Results Results showed statistically lower dose and concentrations in men compared to the women in our investigation group. Also, female patients demonstrated higher mean scores (cumulative and subscores) within the same dosing regimens of mycophenolic acid. The gastrointestinal score was significantly higher in women who received a dose greater than 720 mg compared to men (0.20 ± 0.12 vs 0.12 ± 0.12). Women demonstrated higher individual adverse effects such as diarrhea and skin changes (41.7 vs 17.0; p = 0.038 and 62.5 vs 30.2; p = 0.037, respectively). Conclusions The results of our research showed that recipients' gender may play an important role in pharmacokinetic profile of mycophenolic acid, suggesting that women had higher concentration of mycophenolic acid and more serious side effects.

Tacrolimus Dose Optimization Strategy for Refractory Ulcerative Colitis Based on the Cytochrome P450 3A5 Polymorphism Prediction Using Trough Concentration after 24 Hours

BACKGROUND

In the tacrolimus treatment for refractory ulcerative colitis (UC), dose adjustment is necessary because the required doses to keep appropriate drug concentrations are significantly different among individuals. Cytochrome P450 (CYP) 3A5 polymorphism affects tacrolimus blood concentrations. However, it is difficult to obtain genetic information in real clinical practice. In the present study, we investigated possible factors that may predict CYP3A5 polymorphism and proposed a dose optimization strategy based on the obtained predicting factors.

SUMMARY

We retrospectively analyzed 41 patients who underwent remission induction therapy with tacrolimus for UC in our hospital. First, we performed a correlation analysis of CYP3A5 polymorphism and pharmacokinetics. In the CYP3A5 non-expressers, the dose of tacrolimus (mg/kg) was lower and dose-adjusted trough levels (ng/mL per mg/kg) were higher compared with those in expressers. Next, we investigated factors that could predict CYP3A5 polymorphism. Trough concentration 24 h following tacrolimus administration was extracted as a significant factor. When the trough cutoff value at 24 h was set to 2.6 ng/mL, sensitivity and specificity for estimation of CYP3A5 polymorphism were 63 and 96% respectively. Therefore, when the trough concentration 24 h after administration is ≤2.6 ng/mL, the patient can be estimated as a CYP3A5 expresser and an increase in dose should be proposed. Key Message: The trough concentration 24 h after the first tacrolimus administration appears to be a useful predictor of -CYP3A5 polymorphism. Performing dose optimization strategy based on the prediction of CYP3A5 polymorphism can lead to earlier and safer remission induction.

Sex differences in transplantation

Sex plays a role in the incidence and progression of a wide variety of diseases and conditions related to transplantation. Additionally, a growing body of clinical and experimental evidence suggests that sex can impact the pharmacokinetics and pharmacodynamics of several commonly used immunosuppressive and anti-infective drugs in transplant recipients. A better understanding of these sex differences will facilitate advances in individualizing treatment for patients and improve outcomes of solid organ transplantation. Here, we provide a review of sex-related differences in transplantation and highlight opportunities for future research directions.

Donor CYP3A5 genotype influences tacrolimus disposition on the first day after paediatric liver transplantation

AIM

The aim of the present study was to investigate the influence of the cytochrome P450 (CYP) 3A4/5 genotype in paediatric liver transplant recipients and donors, and the contribution of age and gender to tacrolimus disposition on the first day after transplantation.

METHODS

The contribution of the CYP3A4/5 genotype in paediatric liver transplant recipients and donors to the tacrolimus blood trough concentrations (C₀ ) and the tacrolimus concentration/weight-adjusted dose ratio on day 1 was evaluated in 67 liver-transplanted children: 33 boys and 34 girls, mean age 4.5 years.

RESULTS

Donor CYP3A5 genotype appears to be significantly associated with tacrolimus disposition on the first day after liver transplantation (P < 0.0002). Other physiological factors, such as recipient age and donor gender may also play a role and lead to significant differences in tacrolimus C₀ and tacrolimus concentration/weight-adjusted dose ratio on day 1. However, according to the general linear model, only recipient age appears to be independently associated with tacrolimus disposition on the first day after liver transplantation (P < 0.03). Indeed, there was a faster tacrolimus metabolism in children under 6 years of age (P < 0.02).

CONCLUSIONS

Donor CYP3A5 genotype, recipient age and, to a lesser extent, donor gender appear to be associated with tacrolimus disposition on day 1 after transplant. This suggests that increasing the starting tacrolimus doses in paediatric patients under 6 years of age who receive a graft from a male extensive metabolizer may enhance the possibility of their tacrolimus levels reaching the therapeutic range sooner.

New-onset diabetes after liver transplantation: a national report from China Liver Transplant Registry

BACKGROUND/AIMS

New-onset diabetes after transplantation (NODAT) is a serious complication of liver transplantation (LT). The present study aimed to investigate the risk factors of NODAT by a national survey using the China Liver Transplant Registry database.

PATIENTS

A total of 10 204 non-pre-existing diabetic patients undergone primary LT between January 2000 and December 2013 were included. Risk factors were identified by logistic regression analysis.

RESULTS

NODAT occurred in 24.3% of liver recipients with a median follow-up time of 2.6 years, and was associated with a significantly lower patient survival. NODAT increased not only diabetes related complications (e.g., infection, kidney failure) but also biliary stricture and cholangitis. NODAT patients who received hypoglycaemic treatment had a worse prognosis and a higher hepatocellular carcinoma recurrence compared with those without treatment. New-onset hyperglycaemia (<30 days) was the major predictor of NODAT. Other risk factors included cold ischaemia time >9 h, recipient age >50 years, body mass index >25 kg/m(2) , other hepatitis (mainly hepatitis C), post-transplant intensive care unit stay >15 days, cytomegalovirus infection and corticosteroid at discharge.

CONCLUSIONS

The incidence of NODAT in China is similar to that in Western countries. However, the NODAT-related complications are more common and severer in China compared with those in Western countries. The major risk factors are different.

Monitoring the Intracellular Tacrolimus Concentration in Kidney Transplant Recipients with Stable Graft Function

Although monitoring the intracellular concentration of immunosuppressive agents may be a promising approach to individualizing the therapy after organ transplantation, additional studies on this issue are needed prior to its clinical approval. We investigated the relationship between intracellular and whole blood concentrations of tacrolimus (IC-TAC and WB-TAC, respectively), the factors affecting this relationship, and the risk of rejection based upon IC-TAC in stable kidney recipients. Both IC-TAC and WB-TAC were measured simultaneously in 213 kidney recipients with stable graft function using LC-MS/MS. The tacrolimus ratio was defined as IC-TAC per WB-TAC. The genetic polymorphism of ABCB1 gene and flow cytometric analyses were conducted to probe the correlation between tacrolimus concentrations and the immunoreactivity status as a potential risk of rejection, respectively. The correlation between IC-TAC and WB-TAC was relatively linear (r = 0.67; P<0.001). The factors affecting the tacrolimus ratio were sex, hematocrit, and the transplant duration, as follows: a high tacrolimus ratio was noted in female patients, patients with a low hematocrit, and patients with a short transplant period. However, the tacrolimus ratio did not reflect the prior clinical outcomes (e.g., rejection) or the genetic polymorphism of ABCB1. After stimulation with phorbol-12-myristate 13-acetate and ionomycin, the proportion of T cells producing interferon-gamma or interleukin-2 was higher in the low-IC-TAC group than in the high-IC-TAC group. Further studies are required to evaluate the value of the intracellular tacrolimus concentrations in several clinical settings, such as rejection, infection, and drug toxicity.

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

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

Therapeutic drug monitoring of immunosuppressants by liquid chromatography-mass spectrometry

Immunosuppressant medications allow the transplantation of tens of thousands of allografts per year and consequently have great potential to decrease patient morbidity and mortality. However, some medications have great risk associated with over- and under-dosing leading to adverse effects or allograft rejection, respectively. This necessitates immunosuppressant therapeutic drug monitoring accomplished by immunoassay or liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The former's accuracy can be hindered by metabolites of immunosuppressant medications, antibodies against these medications and heterophilic antibodies. Although LC-MS/MS has superior specificity which allows it to be less susceptible to interference, this methodology lacks standardization and the necessary throughput. Recent developments in LC-MS/MS quantitation, however, include patient-friendly sample submission as dried blood spots, higher sample throughput and commercialization. Here we critically review recent LC-MS/MS publications (January 2010 to July 2015) on the quantitation of cyclosporine A, tacrolimus, sirolimus and everolimus.

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

BACKGROUND

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

STUDY DESIGN

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

SETTING & PARTICIPANTS

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

INTERVENTION

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

OUTCOMES & MEASUREMENTS

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

Association of Extrarenal Adverse Effects of Posttransplant Immunosuppression With Sex and ABCB1 Haplotypes

Extrarenal adverse effects (AEs) associated with calcineurin inhibitor (CNI) and mycophenolic acid (MPA) occur frequently but are unpredictable posttransplant complications. AEs may result from intracellular CNI accumulation and low activity of P-glycoprotein, encoded by the ABCB1 gene. Since ABCB1 single nucleotide polymorphisms (SNPs) and sex influence P-glycoprotein, we investigated haplotypes and extrarenal AEs. A prospective, cross-sectional study evaluated 149 patients receiving tacrolimus and enteric coated mycophenolate sodium or cyclosporine and mycophenolate mofetil. Immunosuppressive AE assessment determined individual and composite gastrointestinal, neurologic, aesthetic, and cumulative AEs. Lipids were quantitated after 12-hour fast. ABCB1 SNPs: c.1236C>T (rs1128503), c.2677G>T/A (rs2032582), and c.3435C>T (rs1045642) were determined with haplotype associations computed using the THESIAS program, and evaluated by immunosuppression, sex and race using multivariate general linear models. Tacrolimus patients exhibited more frequent and higher gastrointestinal AE scores compared with cyclosporine with association to CTT (P = 0.018) and sex (P = 0.01). Aesthetic AE score was 3 times greater for cyclosporine with TTC haplotype (P = 0.005). Females had higher gastrointestinal (P = 0.022), aesthetic (P < 0.001), neurologic (P = 0.022), and cumulative AE ratios (P < 0.001). Total cholesterol (TCHOL), low-density lipoproteins (LDL), and triglycerides were higher with cyclosporine. The TTC haplotype had higher TCHOL (P < 0.001) and LDL (P = 0.005). Higher triglyceride (P = 0.034) and lower high-density lipoproteins (P = 0.057) were associated with TTT with sex-adjusted analysis. ABCB1 haplotypes and sex were associated with extrarenal AEs. Using haplotypes, certain female patients manifested more AEs regardless of CNI. Haplotype testing may identify patients with greater susceptibility to AEs and facilitate CNI individualization.

Tacrolimus as a part of immunosuppressive treatment in kidney transplantation patients: sex differences

BACKGROUND

Metabolism interaction between corticosteroids and tacrolimus (Tac) exists and can be an important factor in providing rational pharmacotherapy in kidney transplantation patients. Both Tac and corticosteroids can induce adverse metabolic effects, such as hyperglycemia, post-transplantation diabetes mellitus, and dyslipidemia.

OBJECTIVE

The main goal of this study was to detect corticosteroid dose influence on Tac level within the first 6 months of immunosuppressive therapy. The secondary goal of this research was to investigate sex differences on Tac-corticosteroid interaction. We also monitored biochemical-parameter changes, which are related to immunosuppressive treatment.

METHODS

This retrospective pharmacokinetic study included 30 Serbian patients after kidney transplantation. Patients received a quaternary immunosuppressive regimen including Tac, mycophenolate, mofetil, basiliximab, and corticosteroids. To compare dose-normalized level and dose of Tac in different days after transplantation, we performed the Friedman test and Wilcoxon matched-pairs signed rank sum test. Mann-Whitney test was performed to compare differences in dose of Tac, level of Tac, and dose-normalized level of Tac between male and female patient groups. We used the Friedman test to compare biological and clinical data.

RESULTS

Obtained results show statistical significance between dose of Tac on day 180 post transplantation and dose on days 7, 14, 21, and 60 post transplantation. There was a statistical difference in dose-normalized level of Tac between days 7 and 21 post transplantation (P < 0.01), days 7 and 60 (P < 0.01), and between days 7 and 180 (P < 0.05). There is a statistical significance between male and female levels of Tac on day 21 after transplantation (P < 0.01). Significance also exists on day 60 after transplantation between male and female dose-normalized levels (P < 0.05). There is also a statistical difference in glucose, cholesterol, triglyceride, serum creatinine, and urea level and activity of alanine aminotransferase and alkaline phosphatase before and after operation.

CONCLUSION

Our study shows that dose of corticosteroid affects Tac level in kidney transplantation patients. Tac dose and level changes showed that corticosteroid-Tac interaction has more influence on male than female patients. According to biochemical monitoring, the immunosuppressive therapy used at present is quite well tolerated.