Clinical mycophenolic acid monitoring in liver transplant recipients

Mycophenolate mofetil exposure on embryonic and fetal ear development in rats during pregnancy

BACKGROUND

To explore the pathogenesis of microtia, in this study, the different concentrations of mycophenolate mofetil (MMF) exposure on the development of rat embryonic and fetal ears, in order to establish a drug-induced microtia model, and provide a basis for further exploring the pathogenesis of microtia.

METHODS

The pregnant rat model was established in this study, 56 pregnant SD rats were randomly divided into 4 groups: control group and MMF (50, 100, and 200 mg/kg) group. Solutions were administered to the rats by oral gavage at gestation day (GD) 9 and GD 10 8:00 a.m, once a day. On GD 10.5 and GD 14.5, embryos were evaluated for neural crest development. On GD 20.5, fetuses were evaluated for overall survival and development with particular focus on ear development via morphologic, skeletal, and histologic investigation. Some animals were allowed to deliver their litters and offspring were evaluated on postnatal day 18 for ear development.

RESULTS

A total of 56 pregnant rats, 14 in each group, were included in the study. As a result, depending on MMF dose increase, in experimental groups, it was determined that the statistically significant the development of the first and second branchial arches and derived tissues of the embryo, overall survival, ear development, and length and weight of fetuses. Imaging of MMF groups revealed statistically significant differences in the development of the skull and auditory vesicles of MMF treated fetuses. Histologically, MMF affected the proliferation and differentiation of chondrocytes and the expression of type II collagen.

CONCLUSIONS

Mycophenolate mofetil can lead to the hypoplasia of rat embryos, fetuses, and auricle in a dose-dependent. MMF may affect the migration and proliferation of cranial neural crest cells, and then lead to microtia. MMF may induce the establishment of an animal model of microtia.

Utility of salivary mycophenolic acid concentration monitoring: Modeling and Monte Carlo validation approach

The results of the previous studies demonstrated an association between mycophenolic acid (MPA) exposure, serum albumin level (ALB), and adverse effects in kidney transplant patients. The aim was the identification of mathematical correlation and association between both, total and unbound MPA concentration in relation to ALB, body mass (BM), age and estimated glomerular filtration rate (eGFR) in stable kidney transplant recipients. Furthermore, investigation was conducted with the aim to clarify the role of salivary concentration (CSAL ) of MPA in adverse effect profile. In order to analyze the association between total and salivary concentration of MPA in relation to ALB, BM, age and eGFR, a least squares method for determining the correlation between these parameters was performed. In addition, derived mathematical model based on experimental data can also be performed and simulated through the Monte Carlo (MC) approach. Adverse effects were grouped according to the nature of symptoms and scored by a previously published validated system. Numerically calculated values of CSAL from the models [CSAL  = f(ALB, BM, age, eGFR, CP ) = a00  + a10 *(ALB, BM, age, eGFR) + a01 *CP ] were then compared with those from validation set of patients, where the best fitting model was for ALB [CSAL  = 54.96-1.64*ALB +13.4*CP ]. Adverse effects estimation showed the difference in esthetic score, positively correlated with CSAL in the lower ALB group (145.41 ± 219.02 vs. 354.08 ± 262.19; with statistical significance p = .014) and almost significant for gastrointestinal score (167.69 ± 174.79 vs. 347.55 ± 320.95; p = .247). The study showed that CSAL MPA may contribute to management of adverse effects, but these findings require confirmation of clinical utility.

Personalized Therapy for Mycophenolate: Consensus Report by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

ABSTRACT

When mycophenolic acid (MPA) was originally marketed for immunosuppressive therapy, fixed doses were recommended by the manufacturer. Awareness of the potential for a more personalized dosing has led to development of methods to estimate MPA area under the curve based on the measurement of drug concentrations in only a few samples. This approach is feasible in the clinical routine and has proven successful in terms of correlation with outcome. However, the search for superior correlates has continued, and numerous studies in search of biomarkers that could better predict the perfect dosage for the individual patient have been published. As it was considered timely for an updated and comprehensive presentation of consensus on the status for personalized treatment with MPA, this report was prepared following an initiative from members of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT). Topics included are the criteria for analytics, methods to estimate exposure including pharmacometrics, the potential influence of pharmacogenetics, development of biomarkers, and the practical aspects of implementation of target concentration intervention. For selected topics with sufficient evidence, such as the application of limited sampling strategies for MPA area under the curve, graded recommendations on target ranges are presented. To provide a comprehensive review, this report also includes updates on the status of potential biomarkers including those which may be promising but with a low level of evidence. In view of the fact that there are very few new immunosuppressive drugs under development for the transplant field, it is likely that MPA will continue to be prescribed on a large scale in the upcoming years. Discontinuation of therapy due to adverse effects is relatively common, increasing the risk for late rejections, which may contribute to graft loss. Therefore, the continued search for innovative methods to better personalize MPA dosage is warranted.

Mycophenolate mofetil-induced liver injury in a patient with aquaporin-4 antibody positive transverse myelitis

We present a case of a 49-year-old woman diagnosed with aquaporin-4 antibody-positive transverse myelitis, who developed a significant transaminitis 2 months after commencing mycophenolate mofetil (MMF) as a steroid-sparing agent. No other risk factors were identified, a blood liver panel was negative and liver biopsy showed features compatible with drug-induced liver injury (DILI). MMF was stopped with a corresponding normalisation of serum alanine aminotransferase over the next 2 months. This case highlights MMF as a rare cause of DILI and provides justification for monitoring of liver biochemistry on therapy.

Investigation of hub genes and immune status in heart transplant rejection using endomyocardial biopsies

T cell‒mediated rejection (TCMR) and antibody‐mediated rejection (ABMR) are severe post‐transplantation complications for heart transplantation (HTx), whose molecular and immunological pathogenesis remains unclear. In the present study, the mRNA microarray data set GSE124897 containing 645 stable, 52 TCMR and 144 ABMR endomyocardial biopsies was obtained to screen for differentially expressed genes (DEGs) between rejected and stable HTx samples and to investigate immune cell infiltration. Functional enrichment analyses indicated roles of the DEGs primarily in immune‐related mechanisms. Protein‐protein interaction networks were then constructed, and ICAM1, CD44, HLA‐A and HLA‐B were identified as hub genes using the maximal clique centrality method. Immune cell infiltration analysis revealed differences in adaptive and innate immune cell populations between TCMR, ABMR and stable HTx samples. Additionally, hub gene expression levels significantly correlated with the degree and composition of immune cell infiltration in HTx rejection samples. Furthermore, drug‐gene interactions were constructed, and 12 FDA‐approved drugs were predicted to target hub genes. Finally, an external GSE2596 data set was used to validate the expression of the hub genes, and ROC curves indicated all four hub genes had promising diagnostic value for HTx rejection. This study provides a comprehensive perspective of molecular and immunological regulatory mechanisms underlying HTx rejection.

Tablet or capsule form of generic mycophenolate mofetil (My-Rept®) after liver transplantation: a prospective randomized trial

Background

Tablet and capsule forms have advantages and disadvantages in the market. Generally, the tablet form (500 mg) of mycophenolate mofetil (MMF) is more convenient for drug ingestion and more cost-effective than the capsule form (250 mg). We examined the efficacy and safety of MMF in its different forms combined with tacrolimus in liver transplant recipients.

Methods

A randomized controlled trial was performed to compare the efficacy and safety between the tablet form of MMF (tablet group) and the capsule form of MMF (capsule group) in liver transplant patients. One hundred sixteen patients were enrolled in the present study from 2014 to 2017. Fifty-six patients in the full-analysis set (FAS) population were in the capsule group and 60 were in the tablet group. The primary endpoint was incidence of biopsy-proven acute rejection (BPAR) by 24 weeks after liver transplantation (LT). Secondary endpoints were patient survival, serum creatinine level, and adverse events (AEs).

Results

In the per-protocol population, 45 patients were in the tablet group and 49 were in the capsule group. There were no statistically significant differences in MMF dose, mycophenolic acid trough level, and tacrolimus trough level between the two groups. The incidence of BPAR at 24 weeks after randomization was 6.7% in the tablet group and 6.1% in the capsule group (P=0.627). All patients with BPAR responded well to steroid pulse therapy and increased tacrolimus. Serum creatine level and eGFR were not different between the two groups. The incidence of serious AEs was 7.2% in the tablet group and 7.6% in the capsule group, and none were related to formulation. There was no significant difference in incidence of discontinuations or serious AEs between the two groups.

Conclusion

The present study suggests that the new tablet formulation can be a useful treatment option to maintain a consistent systemic exposure level of MMF, which may help reduce graft failure in liver transplant patients.

Analysis of neoplastic skin complications in transplant patients: experience of an Italian multidisciplinary transplant unit

BACKGROUND

Transplant patients need to be strictly followed, since the immunosuppressive therapies they usually receive can increase the risk of skin complications. This study aims to evaluate the prevalence of neoplastic skin complications in transplant patients.

METHODS

We analyzed 256 liver or kidney transplant patients. The follow-up mean period was 7±3.5 years. It was also evaluated the prevalence of cutaneous neoplastic complications according to the immunosuppressive regimen received by patients as follows: cyclosporine, tacrolimus, steroids, mycophenolate mofetil or everolimus, in single, double or triple therapy.

RESULTS

The 18.36% of patients developed neoplastic complications, among these 9.37% actinic keratoses, 8.20% non-melanoma skin cancer, and 0.78% cutaneous melanoma. Among patients who developed non melanoma skin cancer, 61.90% had basal cell carcinoma, 23.81% squamous cell carcinoma, 52% Kaposi's sarcoma and 4.76%, Malherbe's epithelioma.

CONCLUSIONS

This study demonstrated the increased risk of skin cancer in transplant patients during the first 7 years of follow-up and made the dermatologists aware about the need of a regular cutaneous follow-up for this subset of patients.

Effects of diammonium glycyrrhizinate on hepatic and intestinal UDP-Glucuronosyltransferases in rats: Implication in herb-drug interactions

Glycyrrhizin is a major bioactive component of liquorice, which exerts multiple biochemical and pharmacological activities and is frequently used in combination with other drugs in the clinic. Mycophenolate mofetil (MMF), an immunosuppressant widely used in transplant patients, is metabolized by UDP-glucuronyltransferases (UGTs). Although significant evidence supports that glycyrrhizin could interact with the cytochrome P450s (CYPs), few studies have addressed its effects on UGTs. The present study aimed at investigating the regulatory effects of diammonium glycyrrhizinate (GLN) on UGTs in vitro and in vivo. We found that long-term administration of GLN in rats induced overall metabolism of MMF, which might be due to the induction of UGT1A protein expression. Hepatic UGT1A activity and UGT1A mRNA and protein expression were significantly increased in GLN-treated rats. UGT1A expression levels were also increased in the intestine, contradicting with the observed decrease in intestinal UGT1A activities. This phenomenon may be attributed to different concentrations of glycyrrhetinic acid (GA) in liver and intestine and the inhibitory effects of GA on UGT1A activity. In conclusion, our study revealed that GLN had multiple effects on the expression and activities of UGT1A isoforms, providing a basis for a better understanding of interactions between GLN and other drugs.

1-Alpha, 25-dihydroxyvitamin D3 alters the pharmacokinetics of mycophenolic acid in renal transplant recipients by regulating two extrahepatic UDP-glucuronosyltransferases 1A8 and 1A10

Mycophenolic acid (MPA) is an important immunosuppressant broadly used in renal transplantation. However, the large inter-patient variability in mycophenolic acid (MPA) pharmacokinetics (PK) limits its use. We hypothesize that extrahepatic metabolism of MPA may have significant impact on MPA PK variability. Two intestinal UDP-glucuronosyltransferases 1A8 and 1A10 plays critical role in MPA metabolism. Both in silico and previous genome-wide analyses suggested that vitamin D (VD) may regulate intestinal UGT1A expression. We validated the VD response elements (VDREs) across the UGT1A locus with chromatin immunoprecipitation (ChIP) and luciferase reporter assays. The impact of 1-alpha,25-dihydroxyvitamin D3 (D3) on UGT1A8 and UGT1A10 transcription and on MPA glucuronidation was tested in human intestinal cell lines LS180, Caco-2 and HCT-116. The correlation between transcription levels of VD receptor (VDR) and the two UGT genes were examined in human normal colorectal tissue samples (n = 73). PK alterations of MPA following the parent drug, mycophenolate mofetil (MMF), and D3 treatment was assessed among renal transplant recipients (n = 10). Our ChIP assay validate three VDREs which were further demonstrated as transcriptional enhancers with the luciferase assays. D3 treatment significantly increased transcription of both UGT genes as well as MPA glucuronidation in cells. The VDR mRNA level was highly correlated with that of both UGT1A8 and UGT1A10 in human colorectal tissue. D3 treatment in patients led to about 40% reduction in both AUC_0-12 and Cmax while over 70% elevation of total clearance of MPA. Our study suggested a significant regulatory role of VD on MPA metabolism and PK via modulating extrahepatic UGT activity.

Cardiovascular risk after orthotopic liver transplantation, a review of the literature and preliminary results of a prospective study

Improved surgical techniques and greater efficacy of new anti-rejection drugs have significantly improved the survival of patients undergoing orthotopic liver transplantation (OLT). This has led to an increased incidence of metabolic disorders as well as cardiovascular and cerebrovascular diseases as causes of morbidity and mortality in OLT patients. In the last decade, several studies have examined which predisposing factors lead to increased cardiovascular risk (i.e., age, ethnicity, diabetes, NASH, atrial fibrillation, and some echocardiographic parameters) as well as which factors after OLT (i.e., weight gain, metabolic syndrome, immunosuppressive therapy, and renal failure) are linked to increased cardiovascular mortality. However, currently, there are no available data that evaluate the development of atherosclerotic damage after OLT. The awareness of high cardiovascular risk after OLT has not only lead to the definition of new but generally not accepted screening of high risk patients before transplantation, but also to the need for careful patient follow up and treatment to control metabolic and cardiovascular pathologies after transplant. Prospective studies are needed to better define the predisposing factors for recurrence and de novo occurrence of metabolic alterations responsible for cardiovascular damage after OLT. Moreover, such studies will help to identify the timing of disease progression and damage, which in turn may help to prevent morbidity and mortality for cardiovascular diseases. Our preliminary results show early occurrence of atherosclerotic damage, which is already present a few weeks following OLT, suggesting that specific, patient-tailored therapies should be started immediately post OLT.

A Rationale for Age-Adapted Immunosuppression in Organ Transplantation

Demographic changes are associated with a steady increase of older patients with end-stage organ failure in need for transplantation. As a result, the majority of transplant recipients are currently older than 50 years, and organs from elderly donors are more frequently used. Nevertheless, the benefit of transplantation in older patients is well recognized, whereas the most frequent causes of death among older recipients are potentially linked to side effects of their immunosuppressants.Immunosenescence is a physiological part of aging linked to higher rates of diabetes, bacterial infections, and malignancies representing the major causes of death in older patients. These age-related changes impact older transplant candidates and may have significant implications for an age-adapted immunosuppression. For instance, immunosenescence is linked to lower rates of acute rejections in older recipients, whereas the engraftment of older organs has been associated with higher rejection rates. Moreover, new-onset diabetes mellitus after transplantation is more frequent in the elderly, potentially related to corticosteroids, calcineurin inhibitors, and mechanistic target of rapamycin inhibitors.This review presents current knowledge for an age-adapted immunosuppression based on both, experimental and clinical studies in and beyond transplantation. Recommendations of maintenance and induction therapy may help to improve graft function and to design future clinical trials in the elderly.