Paediatric use of mycophenolate mofetil

Improving Psychological Health Outcomes in Children with Atopic Dermatitis

Introduction

Atopic dermatitis (AD) is a chronic inflammatory skin disease that usually develops in early childhood. AD has a significant impact on quality of life and psychological health outcomes in both adults and children. There are increased reported rates of psychiatric comorbidities including anxiety, depression, ADHD and suicidal ideation compared to the general population. Primary caregivers of children with pediatric eczema and their families may also have derangements in psychological health and quality of life. A number of interventions exist for AD and address wellbeing outcomes as an important aspect of effective treatment.

Methods

A comprehensive literature search was conducted using PubMed/Medline, Embase, the Cochrane Central Register of Controlled Trials in February 2023. Published studies up to April 2023 were included related to interventions for childhood AD that included psychological health or quality of life outcomes. These interventions were stratified according to type and evidence quality.

Results

Search strategy revealed a wide variety of interventions with demonstrated improvements in quality of life or wellbeing of patients with pediatric AD or their families. Both pharmacological and non-pharmacological interventions demonstrated effectiveness in improving disease outcomes.

Conclusion

A variety of both pharmacological and non-pharmacological interventions may be employed to improve psychological health outcomes in children with AD.

Significant Effects of Renal Function on Mycophenolic Acid Total Clearance in Pediatric Kidney Transplant Recipients with Population Pharmacokinetic Modeling

BACKGROUND AND OBJECTIVES

Mycophenolic acid (MPA) is an immunosuppressant commonly prescribed in pediatric kidney transplantation to prevent graft rejection. Large variabilities in MPA plasma exposures have been observed in this population, which could result in severe adverse effects. The majority of the MPA pharmacokinetic data have been reported in adult populations, whereas information in pediatric patients is still very limited. The objective of this study was to establish a novel, nonlinear mixed-effects model for MPA and investigate the clinical variables affecting MPA population pharmacokinetics in pediatric kidney transplant recipients.

METHODS

Data were collected retrospectively from pediatric kidney transplant patients (≤ 18 years when MPA concentrations were initially collected; on oral administration of mycophenolate mofetil) in Calgary, Alberta, Canada. Nonlinear mixed-effect modeling was conducted using stochastic approximation expectation-maximization in Monolix 2021R2 (Lixoft SAS, France) to determine population pharmacokinetic estimates, interindividual variabilities, and interoccasional variabilities. Covariate models were constructed using the Model Proposal function in Monolix in conjunction with a systematic stepwise inclusion/elimination protocol. The best model was selected based on objective function values, relative standard errors, goodness-of-fit plots, prediction-corrected visual predictive checks, and numerical predictive checks.

RESULTS

A total of 50 pediatric kidney transplant patients (25 female) with 219 MPA plasma concentration-time profiles were included. The average age (± standard deviation) and posttransplant time for the sample population were 12.8 ± 4.8 years and 762 ± 1160 days, respectively. The majority of study subjects (i.e., > 85% based on all occasions) were co-administered tacrolimus. A two-compartment, first-order absorption with lag time and linear elimination structural model with lognormal distributed proportional residual errors best described the MPA concentration-time data. The absorption rate constant (2.52 h-1 or 0.042 min-1), lag time (0.166 h or 9.96 min), volumes of distributions of the central (22.8 L) and peripheral (216 L) compartments, and intercompartment clearance (17.6 L h-1 or 0.293 L min-1) were consistent with literature values; whereas total MPA clearance (0.72 L h-1 or 0.012 L min-1) was relatively reduced, likely due to the general lack of cyclosporine interactions and the stabilized graft functions from significantly longer posttransplant time in our sample population. Of the clinical variables tested, only estimated glomerular filtration rate (eGFR) was identified a significant covariate affecting total MPA clearance with a positive, exponential relationship. The final population pharmacokinetic model was successfully evaluated/validated using a variety of complementary methods.

CONCLUSION

We have successfully constructed and validated a novel population pharmacokinetic model of MPA in pediatric kidney transplant patients. A positive, nonlinear relationship between eGFR and total MPA clearance identified in our model is likely attributed to multiple concurrent mechanisms, which warrant further systematic investigations.

High-performance liquid chromatography with fluorescence detection for mycophenolic acid determination in saliva samples

BACKGROUND

For therapeutic drug monitoring (TDM) of mycophenolic acid (MPA), which is frequently proposed, saliva might be a suitable and easy-to-obtain biological matrix. The study aimed to validate an HPLC method with fluorescence detection for determining mycophenolic acid in saliva (sMPA) in children with nephrotic syndrome.

METHODS

The mobile phase was composed of methanol and tetrabutylammonium bromide with disodium hydrogen phosphate (pH 8.5) at a 48:52 ratio. To prepare the saliva samples, 100 µL of saliva, 50 µL of calibration standards, and 50 µL of levofloxacin (used as an internal standard) were mixed and evaporated to dryness at 45 °C for 2 h. The resulting dry extract was reconstituted in the mobile phase and injected into the HPLC system after centrifugation. Saliva samples from study participants were collected using Salivette^® devices.

RESULTS

The method was linear within the range of 5-2000 ng/mL, was selective with no carry-over effect and met the acceptance criteria for within-run and between-run accuracy and precision. Saliva samples can be stored for up to 2 h at room temperature, for up to 4 h at 4 °C, and for up to 6 months at - 80 °C. MPA was stable in saliva after three freeze-thaw cycles, in dry extract for 20 h at 4 °C, and for 4 h in the autosampler at room temperature. MPA recovery from Salivette^® cotton swabs was within the range of 94-105%. The sMPA concentrations in the two children with nephrotic syndrome who were treated with mycophenolate mofetil were within 5-112 ng/mL.

CONCLUSIONS

The sMPA determination method is specific, selective, and meets the validation requirements for analytic methods. It may be used in children with nephrotic syndrome; however further studies are required to investigate focusing on sMPA and the correlation between sMPA and total MPA and its possible contribution to MPA TDM is required.

Limited sampling strategy to predict free mycophenolic acid area under the concentration-time curve in paediatric patients with nephrotic syndrome

In paediatric patients, there is no data on the recommended area under the concentration-time curve from 0 to 12 h (AUC_0-12 ) for free mycophenolic acid (fMPA), which is the active form of the drug, responsible for the pharmacological effect. We decided to establish the limited sampling strategy (LSS) for fMPA for its use in MPA therapeutic monitoring in children with nephrotic syndrome treated with mycophenolate mofetil (MMF). This study included 23 children (aged 11 ± 4 years) from whom eight blood samples were collected within 12 h after MMF administration. The fMPA was determined using the high-performance liquid chromatography with fluorescence detection method. LSSs were estimated with the use of R software and bootstrap procedure. The best model was chosen based on a number of profiles with AUC predicted within ± 20% of AUC_0-12 (good guess), r² , mean prediction error (%MPE) of ±10% and mean absolute error (%MAE) of less than 25%. The fMPA AUC_0-12 was 0.1669 ± 0.0697 μg h/mL and the free fraction was within 0.16%-0.81%. In total, there were 92 equations developed of which five fulfilled the acceptance criteria for %MPE, %MAE, good guess >80% and r²  > 0.900. These equations consisted of three time points: model 1 (C₁ , C₂ , C₆ ), model 2 (C₁ , C₃ , C₆ ), model 3 (C₁ , C₄ , C₆ ), model 5 (C₀ , C₁ , C₂ ), and model 6 (C₁ , C₂ , C₉ ). Although blood sampling up to 9 h after MMF dosing is impractical, it is crucial to include C₆ or C₉ in LSS to assess fMPA AUC_pred correctly. The most practical fMPA LSS, which fulfilled the acceptance criteria in the estimation group, was fMPA AUC_pred  = 0.040 + 2.220 × C₀  + 1.130 × C₁  + 1.742 × C₂ . Further studies should define the recommended fMPA AUC_0-12 value in children with nephrotic syndrome.

Systemic treatment of children and adolescents with atopic dermatitis aged ≥2 years: a Delphi consensus project mapping expert opinion in Northern Europe

BACKGROUND

Paediatric atopic dermatitis (AD) can be burdensome, affecting mental health and impairing quality of life for children and caregivers. Comprehensive guidelines exist for managing paediatric AD, but practical guidance on using systemic therapy is limited, particularly for new therapies including biologics and Janus kinase (JAK) inhibitors, recently approved for various ages in this indication.

OBJECTIVES

This expert consensus aimed to provide practical recommendations within this advancing field to enhance clinical decision-making on the use of these and other systemics for children and adolescents aged ≥2 years with moderate-to-severe AD.

METHODS

Nineteen physicians from Northern Europe were selected for their expertise in managing childhood AD. Using a two-round Delphi process, they reached full or partial consensus on 37 statements.

RESULTS

Systemic therapy is recommended for children aged ≥2 years with a clear clinical diagnosis of severe AD and persistent disease uncontrolled after optimizing non-systemic therapy. Systemic therapy should achieve long-term disease control and reduce short-term interventions. Recommended are cyclosporine A for short-term use (all ages) and dupilumab or methotrexate for long-term use (ages ≥6 years). Consensus was not reached on the best long-term systemics for children aged 2-6 years, although new systemic therapies will likely become favourable: New biologics and JAK inhibitors will soon be approved for this age group, and more trial and real-world data will become available.

CONCLUSIONS

This article makes practical recommendations on the use of systemic AD treatments for children and adolescents, to supplement international and regional guidelines. It considers the systemic medication that was available for children and adolescents with moderate-to-severe AD at the time this consensus project was done: azathioprine, cyclosporine A, dupilumab, methotrexate, mycophenolate mofetil and oral glucocorticosteroids. We focus on the geographically similar Northern European countries, whose healthcare systems, local preferences for AD management and reimbursement structures nonetheless differ significantly.

Reversal of cancer gene expression identifies repurposed drugs for diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG) is an aggressive incurable brainstem tumor that targets young children. Complete resection is not possible, and chemotherapy and radiotherapy are currently only palliative. This study aimed to identify potential therapeutic agents using a computational pipeline to perform an in silico screen for novel drugs. We then tested the identified drugs against a panel of patient-derived DIPG cell lines. Using a systematic computational approach with publicly available databases of gene signature in DIPG patients and cancer cell lines treated with a library of clinically available drugs, we identified drug hits with the ability to reverse a DIPG gene signature to one that matches normal tissue background. The biological and molecular effects of drug treatment was analyzed by cell viability assay and RNA sequence. In vivo DIPG mouse model survival studies were also conducted. As a result, two of three identified drugs showed potency against the DIPG cell lines Triptolide and mycophenolate mofetil (MMF) demonstrated significant inhibition of cell viability in DIPG cell lines. Guanosine rescued reduced cell viability induced by MMF. In vivo, MMF treatment significantly inhibited tumor growth in subcutaneous xenograft mice models. In conclusion, we identified clinically available drugs with the ability to reverse DIPG gene signatures and anti-DIPG activity in vitro and in vivo. This novel approach can repurpose drugs and significantly decrease the cost and time normally required in drug discovery.

Recent research on immunotherapy for anti-N-methyl-D-aspartate receptor encephalitis

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a central nervous system disease characterized by neurological and psychiatric symptoms. Immunotherapy is the basic treatment for this disease, including first- and second-line therapies for the acute stage and the long-course therapy for the chronic stage. Anti-NMDAR encephalitis often has a good prognosis, but some patients may still have neurological dysfunction due to poor response to current immunotherapy. In addition, the adverse reactions and economic burden of drugs are practical problems in clinical practice. To solve the above problems, continuous improvements have been made in immunotherapy regimens in terms of dose, route of administration, and course of treatment, and some new immunotherapy drugs have emerged. This article reviews the recent research on immunotherapy for anti-NMDAR encephalitis.

Pharmacogenomics in Children

Historically genetics has not been considered when prescribing drugs for children. However, it is clear that genetics are not only an important determinant of disease in children but also of drug response for many important drugs that are core agents used in the therapy of common problems in children. Advances in therapy and in the ethical construct of children's research have made pharmacogenomic assessment for children much easier to pursue. It is likely that pharmacogenomics will become part of the therapeutic decision-making process for children, notably in areas such as childhood cancer where weighing benefits and risks of therapy is crucial.

Mycophenolate Mofetil Hepatotoxicity Associated With Mitochondrial Abnormality in Liver Transplant Recipients and Mice

OBJECTIVES

Mycophenolate mofetil (MMF) is a widely used immunosuppressive agent. MMF hepatotoxicity has been reported in non-transplant and renal transplant patients with minimal histologic description. This is the first study describing detailed histology and ultrastructure of MMF hepatotoxicity.

METHODS

Four liver-transplant recipients (Cases 1-4) were suspected to have MMF hepatotoxicity. Cases 1-3 (two females and one male; 4-17 years) had multiple biopsies for liver function test (LFT) abnormalities. Case 4 (female; 16 years) had a surveillance biopsy. Electron-microscopic examination (EM) was requested on Cases 1-3 for unexplained, persistent LFT elevation and histologic abnormalities despite therapy and Case 4 for unexplained histologic abnormalities despite a stable clinical course. To confirm the pathologic changes in the human allografts, livers from MMF-treated and untreated mice were also reviewed.

RESULTS

While the allograft biopsies showed nonspecific histologic changes, EM revealed unequivocal mitochondrial abnormalities similar to those seen in primary and secondary mitochondrial disorders. In Cases 1 and 2, LFTs improved after stopping and reducing MMF, respectively. In Case 3, pre- and post-MMF treatment biopsies were performed and only the post-MMF biopsy demonstrated mitochondrial abnormalities. Mitochondrial abnormality in Case 4 was subclinical. The mouse study confirmed that MMF caused various stress changes in the mitochondria; number of mitochondria/cell (mean ± standard deviation; untreated group: 58.25 ± 8.426; MMF-treated group: 76.37 ± 18.66), number of lipid droplets/cell (untreated: 0.9691 ± 1.150; MMF-treated: 3.649 ± 4.143) and sizes of mitochondria (μm, untreated: 0.8550 ± 0.3409; MMF-treated: 0.9598 ± 0.5312) were significantly increased in hepatocytes in the MMF-treated mice compared with the untreated mice (P < 0.0001).

CONCLUSIONS

Although MMF is safe for the majority of patients, MMF can cause mitochondrial stress, which may trigger more severe mitochondrial abnormalities in a small subset. MMF hepatotoxicity should be considered for MMF-treated patients with unexplained, persistent LFT abnormalities and nonspecific histologic findings. EM should be requested for these cases.

Mycophenolate Mofetil Versus Cyclophosphamide for Remission Induction in Childhood Polyarteritis Nodosa: An Open-Label, Randomized, Bayesian Noninferiority Trial

OBJECTIVE

Cyclophosphamide (CYC) is used in clinical practice off-label for the induction of remission in childhood polyarteritis nodosa (PAN). Mycophenolate mofetil (MMF) might offer a less toxic alternative. This study was undertaken to explore the relative effectiveness of CYC and MMF treatment in a randomized controlled trial (RCT).

METHODS

This was an international, open-label, Bayesian RCT to investigate the relative effectiveness of CYC and MMF for remission induction in childhood PAN. Eleven patients with newly diagnosed childhood PAN were randomized (1:1) to receive MMF or intravenous CYC; all patients received the same glucocorticoid regimen. The primary end point was remission within 6 months while compliant with glucocorticoid taper. Bayesian distributions for remission rates were established a priori for MMF and CYC by experienced clinicians and updated to posterior distributions on trial completion.

RESULTS

Baseline disease activity and features were similar between the 2 treatment groups. The primary end point was met in 4 of 6 patients (67%) in the MMF group and 4 of 5 patients (80%) in the CYC group. Time to remission was shorter in the MMF group compared to the CYC group (median 7.1 weeks versus 17.6 weeks). No relapses occurred in either group within 18 months. Two serious infections were found to be likely linked to MMF treatment. Physical and psychosocial quality-of-life scores were superior in the MMF group compared to the CYC group at 6 months and 18 months. Combining the prior expert opinion with results from the present study provided posterior estimates of remission of 71% for MMF (90% credibility interval [90% CrI] 51, 83) and 75% for CYC (90% CrI 57, 86).

CONCLUSION

The present results, taken together with prior opinion, indicate that rates of remission induction in childhood PAN are similar with MMF treatment and CYC treatment, and MMF treatment might be associated with better health-related quality of life than CYC treatment.

Treatment optimization of maintenance immunosuppressive agents in pediatric renal transplant recipients

Introduction: Graft survival in pediatric kidney transplant patients has increased significantly within the last three decades, correlating with the discovery and utilization of new immunosuppressants as well as improvements in patient care. Despite these developments in graft survival for patients, there is still improvement needed, particularly in long-term care in pediatric patients receiving grafts from deceased donor patients. Maintenance immunosuppressive therapies have narrow therapeutic indices and are associated with high inter-individual and intra-individual variability.Areas covered: In this review, we examine the impact of pharmacokinetic variability on renal transplantation and its association with age, genetic polymorphisms, drug-drug interactions, drug-disease interactions, renal insufficiency, route of administration, and branded versus generic drug formulation. Pharmacodynamics are outlined in terms of the mechanism of action for each immunosuppressant, potential adverse effects, and the utility of pharmacodynamic biomarkers.Expert opinion: Acquiring abetter quantitative understanding of immunosuppressant pharmacokinetics and pharmacodynamic components should help clinicians implement treatment regimens to maintain the balance between therapeutic efficacy and drug-related toxicity.

The Evaluation of Multiple Linear Regression-Based Limited Sampling Strategies for Mycophenolic Acid in Children with Nephrotic Syndrome

We evaluated mycophenolic acid (MPA) limited sampling strategies (LSSs) established using multiple linear regression (MLR) in children with nephrotic syndrome treated with mycophenolate mofetil (MMF). MLR-LSS is an easy-to-determine approach of therapeutic drug monitoring (TDM). We assessed the practicability of different LSSs for the estimation of MPA exposure as well as the optimal time points for MPA TDM. The literature search returned 29 studies dated 1998–2020. We applied 53 LSSs (n = 48 for MPA, n = 5 for free MPA [fMPA]) to predict the area under the time-concentration curve (AUC_pred) in 24 children with nephrotic syndrome, for whom we previously determined MPA and fMPA concentrations, and compare the results with the determined AUC (AUC_total). Nine equations met the requirements for bias and precision ±15%. The MPA AUC in children with nephrotic syndrome was predicted the best by four time-point LSSs developed for renal transplant recipients. Out of five LSSs evaluated for fMPA, none fulfilled the ±15% criteria for bias and precision probably due to very high percentage of bound MPA (99.64%). MPA LSS for children with nephrotic syndrome should include blood samples collected 1 h, 2 h and near the second MPA maximum concentration. MPA concentrations determined with the high performance liquid chromatography after multiplying by 1.175 may be used in LSSs based on MPA concentrations determined with the immunoassay technique. MPA LSS may facilitate TDM in the case of MMF, however, more studies on fMPA LSS are required for children with nephrotic syndrome.

Disseminated bartonellosis in a child with steroid-dependent nephrotic syndrome receiving mycophenolate mofetil monotherapy

Cat scratch disease, usually a benign infectious disease, may develop as multisystem disease with multiorgan involvement, particularly in immunocompromised patients. We report on a patient who developed disseminated bartonellosis while receiving mycophenolate mofetil monotherapy treating steroid-dependent nephrotic syndrome, highlighting that severe infection can be observed in those patients. Therefore, this category of patients should be cautious when having contact with kittens and receives proper prevention advice.

Population pharmacokinetics of mycophenolic acid in paediatric patients

Mycophenolic acid (MPA) is widely used in paediatric kidney transplant patients and sometimes prescribed for additional indications. Population pharmacokinetic or pharmacodynamic modelling has been frequently used to characterize the fixed, random and covariate effects of MPA in adult patients. However, MPA population pharmacokinetic data in the paediatric population have not been systematically summarized. The objective of this narrative review was to provide an up-to-date critique of currently available paediatric MPA population pharmacokinetic models, with emphases on modelling techniques, pharmacological findings and clinical relevance. PubMed and EMBASE were searched from inception of database to May 2020, where a total of 11 studies have been identified representing kidney transplant (n = 4), liver transplant (n = 1), haematopoietic stem cell transplant (n = 1), idiopathic nephrotic syndrome (n = 2), systemic lupus erythematosus (n = 2), and a combined population consisted of kidney, liver and haematopoietic stem cell transplant patients (n = 1). Critical analyses were provided in the context of MPA absorption, distribution, metabolism, excretion and bioavailability in this paediatric database. Comparisons to adult patients were also provided. With respect to clinical utility, Bayesian estimation models (n = 6) with acceptable accuracy and precision for MPA exposure determination have also been identified and systematically evaluated. Overall, our analyses have identified unique features of MPA clinical pharmacology in the paediatric population, while recognizing several gaps that still warrant further investigations. This review can be used by pharmacologists and clinicians for improving MPA pharmacokinetic-pharmacodynamic modelling and patient care.

Nanoparticulate Mycophenolic Acid Eye Drops - Analytical Validation of a High Performance Liquid Chromatography Assay and Stability Studies

BACKGROUND

Mycophenolic acid (MPA), an immunosuppressive agent, is used orally to reduce corneal graft rejection. However, its oral use is associated with gastrointestinal side effects.

OBJECTIVES

This study aims to prepare: MPA nanoparticle eye drops and a validated analytical method.

METHODS

Aqueous MPA eye drops were prepared by nanoencapsulation of MPA using nanomerics MET (N-palamitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan) at a MET and MPA ratio of 7.5: 1 g g-1 in the presence of glycerol (2.75% w/w). A validated MPA formulation drug substance assay was then conducted.

RESULTS

MET-MPA formulations were prepared as well as a validated assay. Assay validation parameters for the analysis of MPA in the formulation were satisfactory [Plate count = 16458, capacity Factor = 2.4, Tailing Factor = 1.02, linearity = 0.999 (0.016-0.5 mg mL-1), limit of detection = 0.056 mg mL-1, limit of quantification = 0.17 mg mL-1, accuracy = 98%, intraday and interday relative standard deviation = 0.45% and 4% respectively]. The candidate formulation (z-average mean = 66 ± 0.4 nm, polydispersity index = 0.12 ± 0.012, drug content = 1.14 ± 0.003 mg mL-1, zeta potential = +8.5 ± 1.4 mV, pH = 7.4 ± 0.02, osmolarity = 309 ± 1.5 mOSm L-1, viscosity = 1.04 ± 0.001 mPa.s) was then found to be stable for 14 days with respect to drug content at refrigeration, room and accelerated (40ºC) temperature. All other formulation parameters were within the ocular comfort range.

CONCLUSION

A validated assay (ICH and US FDA guidelines) for new MPA nanoparticle eye drops has been developed.

Validated LC-MS/MS method for quantitation of total and free mycophenolic acid concentration and its application to a pharmacokinetic study in pediatric renal transplant recipients

A simple and sensitive LC-MS/MS method was established to quantify total and free mycophenolic acid (MPA) plasma concentrations during immunosuppressive medication for pediatric renal transplantation. The chromatographic separation was performed with the Hypersil GOLD C₁₈ column, using a mobile phase consisting of 0.1% formic acid in water and acetonitrile (60:40, v/v) at an isocratic flow rate of 0.4 ml/min. An Agilent 6420 triple quadrupole mass spectrometer was operated via a positive electrospray ionization interface using the transitions m/z 321.14 → 206.9 for MPA and m/z 324.15 → 209.9 for MPA-d3 (internal standard). The linearity was 0.1-50 μg/ml for total MPA and 0.0025-0.5 μg/ml for free MPA. The within-run and between-run precisions were all <5% and accuracy was within 96.23-107.63%. The validated method was successfully aspplied to a pharmacokinetic study in 28 pediatric renal recipients. The mean free fraction of MPA in our patients was 0.89% (ranging from 0.62 to 1.25%) and albumin level played a major role in the variability of free fraction of MPA, thus, in pediatric patients with hypoproteinemia, close free drug monitoring and dose adjustments should be considered to prevent toxicity.

Bullous pemphigoid in adolescence, a rare demographic

Bullous pemphigoid is rarely seen in adolescence, and its presentation, clinical course, and treatment can differ to that found in other age groups. We present a case of bullous pemphigoid in a 16-year-old with features of koebnerisation and oral mucosal involvement and provide a brief review of paediatric bullous pemphigoid.

Childhood atopic dermatitis: current developments, treatment approaches, and future expectations

Atopic dermatitis (AD) is the most common chronic inflammatory skin disorder of childhood. Underlying factors that contribute to AD are impaired epithelial barrier, alterations in the lipid composition of the skin, immunological imbalance including increased Th2/Th1 ratio, proinflammatory cytokines, decreased T regulatory cells, genetic mutations, and epigenetic alterations. Atopic dermatitis is a multifactorial disease with a particularly complicated pathophysiology. Discoveries to date may be considered the tip of the iceberg, and the increasing number of studies in this field indicate that there are many points to be elucidated in AD pathophysiology. In this review, we aimed to illustrate the current understanding of the underlying pathogenic mechanisms in AD, to evaluate available treatment options with a focus on recently discovered therapeutic agents, and to determine the personal, familial, and economic burdens of the disease, which are frequently neglected issues in AD. Currently available therapies only provide transient solutions and cannot fully cure the disease. However, advances in the understanding of the pathogenic mechanisms of the disease have led to the production of new treatment options, while ongoing drug trials also have had promising results.

Mycophenolate mofetil in paediatric autoimmune or immune-mediated diseases of the central nervous system: clinical experience and recommendations

AIM

To gather data on mycophenolate mofetil (MMF) in paediatric autoimmune/immune-mediated central nervous system (CNS) conditions, focusing on safety and factors that may affect MMF efficacy.

METHOD

Retrospective, multicentre study based on four paediatric neurology centres.

RESULTS

Forty-four children were included (30 females, 14 males): 19 had proven/suspected autoimmune encephalitis, 14 had inflammatory demyelinating CNS diseases, and 11 had other autoimmune/immune-mediated CNS conditions. Before MMF, all received first-line immune therapies, and 17 had second-line rituximab and/or cyclophosphamide. MMF was started at a median of 9.5 months from disease onset (range 1-127mo) (median age 9y 4mo, range 1y 5mo-16y 5mo), and was used for median 18 months (range 0.3-73mo). On MMF, 31 patients were relapse-free, whereas eight relapsed (excluding patients with chronic-progressive course). Relapses on MMF were associated with medication weaning/cessation, or with suboptimal MMF dosage/duration. Adverse events of MMF occurred in eight patients: six moderate (gastrointestinal, movement disorder, dermatological) and two severe (infectious).

INTERPRETATION

MMF use in paediatric neuroimmunology is heterogeneous, although relatively safe. We have identified factors that may affect MMF efficacy and provide recommendations on MMF usage.

WHAT THIS PAPER ADDS

Mycophenolate mofetil (MMF) use was heterogeneous with relatively common adverse events, although mostly not severe. MMF treatment reduced median annualized relapse rate, although 20% of patients relapsed on MMF. A high relapse rate pre-MMF and late MMF start were associated with higher probability of relapsing on MMF. Most relapses were associated with suboptimal MMF dosage, short MMF duration, or concurrent medication weaning/discontinuation.

An update on the topical and oral therapy options for treating pediatric atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is one of the most common childhood skin disorders. Multiple mechanisms contribute to the pathology of AD and treatment approaches are directed at these processes.

AREAS COVERED

The purpose of this review is to discuss the chemical treatment options for pediatric atopic dermatitis, including immunomodulators and small molecule inhibitors. A systematic literature search was conducted, and publications were reviewed for applicable treatment guidelines.

EXPERT OPINION

Topical therapy is first-line for pediatric atopic dermatitis. Providers should work closely with patients and caregivers to promote the success of topical treatments. In disease refractory to topical treatments, systemic agents may be considered. Clinical trials are ongoing for the use of biologics in the treatment of pediatric AD. When choosing the most appropriate treatment, physicians should consider the drug efficacy, potential adverse effects, patient adherence, and quality of life for both patients and caregivers. Additional studies are required to determine the safest and most effective doses for systemic therapy in childhood AD.

Mycophenolate mofetil, azathioprine and methotrexate usage in paediatric anti-NMDAR encephalitis: A systematic literature review

BACKGROUND

Available data on mycophenolate mofetil (MMF), azathioprine (AZA) and methotrexate (MTX) for paediatric-onset anti-N-methyl-d-aspartate receptor encephalitis (anti-NMDARE) is limited.

METHODS

Systematic literature review on patients treated with MMF/AZA/MTX for paediatric-onset anti-NMDARE, with focus on modes of use, efficacy and safety.

RESULTS

87 patients were included (age at onset median 11 years, range 0.8-18 years; 69% females). 46% had a relapsing course. 52% received MMF, 27% AZA, 15% MTX, and 6% a combination of MMF/AZA/MTX (7 patients received intrathecal MTX). Before MMF/AZA/MTX, 100% patients received steroids, 83% intravenous immunoglobulin and 45% plasma exchange, and 50% received second-line treatments (rituximab/cyclophosphamide). MMF/AZA/MTX were administered >6 months from onset in 51%, and only after relapse in 40%. Worst mRS before MMF/AZA/MTX was median 4.5 (range 3-5). At last follow-up (median 2 years, range 0.2-8.6), median mRS was 1 (range 0-6). Median annualised relapse rate was 0.4 (range 0-6.7) pre-MMF/AZA/MTX (excluding first events), and 0 on MMF/AZA/MTX (mean 0.03, range 0-0.8). 7% patients relapsed on MMF/AZA/MTX. These relapsing patients had low rate of second-line treatments before MMF/AZA/MTX (25%), long median time between onset and MMF/AZA/MTX usage (18 months), and frequently they were started on MMF/AZA/MTX only after relapse (75%). Relapse rate was lower among patients who received first immune therapy ≤30 days (25%) than later (64%), who received second-line treatments at first event (14%) rather than not (64%), who were started on MMF/AZA/MTX after the first (12%) rather than subsequent events (17%), and who were started on MMF/AZA/MTX ≤3 months from onset (33%) rather than later (53%). Adverse reactions to MMF/AZA/MTX occurred in 2 cases (cytomegalovirus colitis and respiratory infection), of grade 3 Common Terminology Criteria for Adverse Events v4.0.

DISCUSSION

Our literature review disclosed heterogeneity in the use of MMF/AZA/MTX in paediatric-onset anti-NMDARE. MMF/AZA/MTX usage is mostly restricted to retrospective cohort descriptions. These agents may reduce risk of relapse, and have a reasonable safety profile, however data on larger cohorts are required to definitively determine effect.

Survival Time to Biopsy-Proven Acute Rejection and Tacrolimus Adverse Drug Reactions in Pediatric Liver Transplantation

BACKGROUND

Despite advances in surgical procedures and the optimization of immunosuppressive therapies in pediatric liver transplantation, acute rejection (AR) and serious adverse drug reaction (ADR) to tacrolimus still contribute to morbidity and mortality. Identifying risk factors of safety and efficacy parameters may help in optimizing individual immunosuppressive therapies. This study aimed to identify peritransplant predictors of AR and factors related to the risk of ADR to tacrolimus in a large Latin American cohort of pediatric liver transplant patients.

METHODS

We performed a retrospective cohort study in a pediatric liver transplant population (n = 72). Peritransplant variables were collected retrospectively including demographic, clinical, laboratory parameters, genomic (CYP3A5 donor and recipients polymorphism), and tacrolimus trough concentrations (C0) over a 2-year follow-up period. Variability in tacrolimus C0 was calculated using percent coefficient of variation and tortuosity. ADR- and AR-free survival rates were calculated using the Kaplan-Meier method, and risk factors were identified by multivariate Cox regression models.

RESULTS

Cox-proportional hazard models identified that high tortuosity in tacrolimus C0 was associated with an 80% increased risk of AR [hazard ratio (HR), 1.80; 95% confidence interval (CI), 1.01-3.22; P < 0.05], whereas steroid in maintenance doses decreased this risk (HR, 0.56; 95% CI, 0.31-0.99; P < 0.05). Forty-six patients experienced at least one ADR including hypomagnesemia, nephrotoxicity, hypertension, malignancies, and tremor as a first event. Multivariate analysis showed that C0 values 10 days before the event (HR, 1.25; 95% CI, 1.21-1.39; P < 0.0001) and CYP3A5 expresser recipients (HR, 2.05; 95% CI, 1.03-4.06; P < 0.05) were independent predictors of ADR.

CONCLUSIONS

Tacrolimus C0 values, its variability, and CYP3A5 polymorphisms were identified as risk factors of AR and tacrolimus ADR. This knowledge may help to control and reduce their incidence in pediatric liver transplant patients. Prospective studies are important to validate these results.

Generic immunosuppressants

Immunosuppressive drugs for solid organ transplantation are critical dose drugs with a narrow therapeutic index. Many of the most commonly used innovator drugs are off patent and have been replicated by generic counterparts, often at substantial cost-savings to the patient. However, serious adverse events caused by the transition from innovator to generic medications, specifically in pediatric solid organ transplant recipients, have questioned these autosubstitutions. The purpose of this review is to summarize the criteria set forth by the regulatory bodies, and to examine how major immunosuppressive drugs conform to these recommendations. Regulatory bodies have established inconsistent criteria to demonstrate bioequivalence between innovator and generic medications, causing approved generic variations to have varying levels of equivalence with the innovator drugs. In order to minimize the risk for under-immunosuppression, the following recommendations have been concluded. Brand prescribing of cyclosporine and tacrolimus are recommended due to evidence of adverse events after conversion to generic formulations and differences in dissolution parameters. Mycophenolate mofetil (MMF) shows better bioequivalence between innovator and generic formulations, however caution should be advised when switching between formulations. The institution of 'innovator only' policies may be appropriate at this time in order to minimize the risk of under-immunosuppressing patients until the evidence of more stringent bioequivalence has been established.

Short-Term Administration of Mycophenolate Is Well-Tolerated in CLN3 Disease (Juvenile Neuronal Ceroid Lipofuscinosis)

Mycophenolate, an immunosuppressant, is commonly used off-label for autoimmune neurological conditions. In CLN3 disease, a neurodegenerative disorder of childhood, preclinical and clinical data suggest secondary autoimmunity and inflammation throughout the central nervous system are key components of pathogenesis. We tested the short-term tolerability of mycophenolate in individuals with CLN3 disease, in preparation for possible long-term efficacy trials of this drug. We conducted a randomized, double-blind, placebo-controlled, crossover study of mycophenolate in 19 ambulatory individuals with CLN3 disease to determine the safety and tolerability of short-term administration (NCT01399047). The study included two 8-week treatment periods with a 4-week intervening washout. Mycophenolate was well tolerated. 89.5% of participants completed the mycophenolate arm, on the assigned study dose (95% CI: 66.9-98.7%), and there were no significant differences in tolerability rates between mycophenolate and placebo arms (10.5%; 95% CI: -3.3-24.3%, p = 0.21). All reported adverse events were mild in severity; the most common adverse events on mycophenolate were vomiting (31.6%; 95% CI: 12.6-56.6%), diarrhea (15.8%; 95% CI: 3.4-39.6%), and cough (15.8%; 95% CI: 3.4-39.6%). These did not occur at a significantly increased frequency above placebo. There were no definite effects on measured autoimmunity or clinical outcomes in the setting of short-term administration. Study of long-term exposure is needed to test the impact of mycophenolate on key clinical features and CLN3 disease trajectory.

Pharmacoepidemiology of tacrolimus in pediatric liver transplantation

AEs during immunosuppressive treatment with tacrolimus are very common. We retrospectively evaluated FK safety and efficacy in a large pediatric liver transplant cohort in Latin America. During 2-year follow-up, we analyzed data from patients who underwent liver transplantation over the period 2010-2012 and recorded FK exposure, AEs, and AR episodes. AEs were classified according causality and severity. Tacrolimus exposure before and during AE was compared using Wilcoxon matched-pairs test. Kaplan-Meier curves were used for survival analysis. In total, 46 patients (out of 72 patients) experienced 69 AEs, such as hypomagnesemia (49%), PTLD (6%), hypertension (6%), and/or nephrotoxicity (22%). 43% of AEs were classified as moderate or serious, and 89% were assigned as probable or definitive. Patients who had one or more AR episodes accounted for 65%. The 12-month acute rejection-free survival was 41% (95% CI, 30.1%-53.1%). A significant difference was observed in FK trough concentrations before and during hypomagnesemia and nephrotoxicity (P<.05). This study is the first report of FK safety in a large group of pediatric liver transplant patients in Latin America. Children experience AEs, even in protocols with low FK doses. Therapeutic monitoring is an important tool to manage immunosuppressive schemes containing tacrolimus in vulnerable populations.

Clinical Pharmacokinetics of Mycophenolic Acid in Hematopoietic Stem Cell Transplantation Recipients

Mycophenolate mofetil (MMF), an ester prodrug of mycophenolic acid (MPA), is widely used as a maintenance immunosuppressive regimen in solid organ transplant patients. It is increasingly used for the prophylaxis and treatment of graft-versus-host disease (GVHD) in hematopoietic stem cell transplantation (HSCT) patients. MPA displays extensive binding to serum albumin and glucuronidation to the inactive MPA-7-O-glucuronide (MPAG). Here, we review and discuss the pertinent information regarding the clinical pharmacokinetics of MPA in HSCT patients. The pharmacokinetics of MPA are altered in HSCT patients with lower oral bioavailability, shorter half-life and higher clearance than those in healthy volunteers and renal transplant recipients. Moreover, clearance may be increased in young pediatric patients. The optimal MMF dosing and preferred targets are still under investigation in HSCT patients due to the substantial intra- and inter-individual pharmacokinetic variability of MPA and broad range of transplants (malignant vs. nonmalignant, related vs. unrelated donor, and human leukocyte antigen mismatch). The complex pharmacokinetics of MPA have partly hampered the efficient use of MMF, and pharmacokinetic studies in HSCT patients have been limited in size and mostly inconclusive. Future research should be multi-institutional and focus on developing clinical decisions with adequate statistical power to improve clinical care of HSCT recipients.

Pharmacokinetics and dynamics of mycophenolate mofetil after single-dose oral administration in juvenile dachshunds

Mycophenolate mofetil (MMF) is recommended as an alternative/complementary immunosuppressant. Pharmacokinetic and dynamic effects of MMF are unknown in young-aged dogs. We investigated the pharmacokinetics and pharmacodynamics of single oral dose MMF metabolite, mycophenolic acid (MPA), in healthy juvenile dogs purpose-bred for the tripeptidyl peptidase 1 gene (TPP1) mutation. The dogs were heterozygous for the mutation (nonaffected carriers). Six dogs received 13 mg/kg oral MMF and two placebo. Pharmacokinetic parameters derived from plasma MPA were evaluated. Whole-blood mitogen-stimulated T-cell proliferation was determined using a flow cytometric assay. Plasma MPA C_max (mean ± SD, 9.33 ± 7.04 μg/ml) occurred at <1 hr. The AUC_0-∞ (mean ± SD, 12.84±6.62 hr*μg/ml), MRT_inf (mean ± SD, 11.09 ± 9.63 min), T1/2 (harmonic mean ± PseudoSD 5.50 ± 3.80 min), and k/d (mean ± SD, 0.002 ± 0.001 1/min). Significant differences could not be detected between % inhibition of proliferating CD5+ T lymphocytes at any time point (p = .380). No relationship was observed between MPA concentration and % inhibition of proliferating CD5+ T lymphocytes (R = .148, p = .324). Pharmacodynamics do not support the use of MMF in juvenile dogs at the administered dose based on existing therapeutic targets.

The compelling case for therapeutic drug monitoring of mycophenolate mofetil therapy

We have reviewed current evidence on the therapeutic drug monitoring (TDM) of mycophenolic acid (MPA) in relationship to drug efficacy and safety. The relationship between actual MPA exposure and mycophenolate mofetil (MMF) dose has been shown to be weak in children and adolescents. The TDM of MPA exposure should ideally be performed using full pharmacokinetic profiles or limited sampling strategies. Recent evidence has provided some rationale for using the post-dose trough level as a single measure. In terms of short-term efficacy, there is strong evidence that a MPA area under the time-concentration curve of >30 mg × h/L reduces acute rejection episodes early after renal transplantation, and there is evolving evidence that aiming for the same exposure over the long term may be a viable strategy to reduce the formation of donor-specific antibodies. Strong evidence also supports the existence of important drug interactions and age/developmental dependent differences in drug metabolism that may necessitate the need for TDM of MMF therapy. Based on these findings and given the substantial inter- and intra-patient variability of MPA exposure, it would appear that MMF therapy should be subject to TDM to avoid over- and under-dosing. This may be a viable strategy to reduce treatment-emergent adverse events and to increase the effective pediatric transplant survival rates.

Pharmacokinetics of Mycophenolic Acid and Dose Optimization in Children After Intestinal Transplantation

BACKGROUND

Mycophenolate mofetil (MMF) or enteric-coated mycophenolate sodium (MPS) is now commonly used in pediatric intestinal transplantation (Tx), but to date, no clear recommendations regarding the dosing regimen have been made in this population. The aim of this study was to determine the MMF/MPS dosage required to achieve an area under the plasma concentration-time curve from 0 to 12 hours (AUC0-12) for mycophenolic acid (MPA) greater than 30 mg·h·L in children after intestinal transplantation.

METHODS

A pharmacokinetic study was conducted in 8 children (median, 9.4 years; range, 0.75-15.8 years) at a median time of 113 months (range, 1.5-160 months) after intestinal transplantation.

RESULTS

MMF was initially introduced at a low median starting dose of 687 mg·m·d (range, 310-1414 mg·m·d). One of the 3 patients who received MPS and 2 of the 6 patients who received MMF had an MPA AUC0-12 value below 30 mg.h.L. The median MMF dosage had to be increased by 91% (1319 mg·m·d versus 687 mg·m·d) to reach AUC0-12 values above the defined target level of 30 mg·h·L.

CONCLUSIONS

When used in combination with tacrolimus and steroids, an initial MMF dose of 600 mg/m twice a day would be recommended to children after intestinal transplantation to achieve MPA exposure similar to those observed in adults and children after the transplantation of other organs. Further studies are required to recommend a suitable dosage for pediatric intestinal transplant recipients who receive MPA.

Monitoring of mycophenolate mofetil metabolites in children with nephrotic syndrome and the proposed novel target values of pharmacokinetic parameters

The aim of the study was to estimate target values of mycophenolate mofetil (MMF) pharmacokinetic parameters in children with proteinuric glomerulopathies by calculating the pharmacokinetic parameters of MMF metabolites (mycophenolic acid [MPA], free MPA [fMPA] and MPA glucuronide [MPAG]) and assessing their relation to proteinuria recurrence. One hundred and sixty-eight blood samples were collected from children, aged 3-18 years, diagnosed with nephrotic syndrome or lupus nephritis. MMF metabolites concentrations were examined before drug administration (Ctrough) and up to 12h afterward employing high-performance liquid chromatography. Dose-normalized MPA Ctrough and area under the concentration-time curve from 0 to 12h (AUC12) were within 0.29-6.47 μg/mL/600 mg/m(2) and 9.97-105.52 μg h/mL/600 mg/m(2), respectively. MPA Ctrough was twofold lower (p=0.024) in children with proteinuria recurrence. MPA, fMPA and MPAG concentrations correlated positively to respective AUC12. It may be suggested MMF metabolites monitoring in children with proteinuric glomerulopathies is justified by MPA Ctrough<2 μg/mL in patients at risk of the proteinuria recurrence. Such a recurrence is most probably caused by not sufficient MPA concentration during proteinuric glomerulopathies treatment. MPA Ctrough>3 μg/mL may be considered as an efficient one to avoid proteinuria recurrence. Finally, MPA target AUC12 should exceed 60 μg h/mL to ensure the safe and effective treatment in children with nephrotic syndrome, however, the upper limit is still to be established.

Bioavailability of a generic of the immunosuppressive agent mycophenolate mofetil in pediatric patients

The use of generic immunosuppressive agents is controversial, especially for the treatment of pediatric patients, as information on the bioavailability of generic immunosuppressants in children is particularly scarce. The aim of the study was to compare the bioavailabilities of two products containing mycophenolate mofetil, the innovator and a generic, in children. Pediatric patients with end-stage renal disease on the waiting list for renal transplantation received a single oral dose of mycophenolate mofetil as either the innovator product (CellCept(®) , Roche) or the generic (Tevacept(®) , Teva Pharmaceuticals). A nine point pharmacokinetic profile was obtained. Mycophenolic acid concentration was quantitated in plasma by HPLC, plasma concentration-against-time curves were constructed, and bioavailability parameters were determined. Pharmaceutical quality analysis of both formulations, including drug content and dissolution profile, was also performed. There were no statistically significant differences between formulations in bioavailability parameters. Interindividual variability was very important, but individual values of AUC, an indicator of the extent of drug absorption, were within the same range for both formulations. The two formulations exhibited similar drug content and dissolution profiles, as well as comparable mycophenolic acid plasma levels in an end-stage renal failure population.

Pharmacokinetic/pharmacodynamic modelling approaches in paediatric infectious diseases and immunology

Pharmacokinetic/pharmacodynamic (PKPD) modelling is used to describe and quantify dose-concentration-effect relationships. Within paediatric studies in infectious diseases and immunology these methods are often applied to developing guidance on appropriate dosing. In this paper, an introduction to the field of PKPD modelling is given, followed by a review of the PKPD studies that have been undertaken in paediatric infectious diseases and immunology. The main focus is on identifying the methodological approaches used to define the PKPD relationship in these studies. The major findings were that most studies of infectious diseases have developed a PK model and then used simulations to define a dose recommendation based on a pre-defined PD target, which may have been defined in adults or in vitro. For immunological studies much of the modelling has focused on either PK or PD, and since multiple drugs are usually used, delineating the relative contributions of each is challenging. The use of dynamical modelling of in vitro antibacterial studies, and paediatric HIV mechanistic PD models linked with the PK of all drugs, are emerging methods that should enhance PKPD-based recommendations in the future.

Pharmacogenomics and adverse drug reactions in children

Adverse drug reactions are a common and important complication of drug therapy in children. Over the past decade it has become increasingly apparent that genetically controlled variations in drug disposition and response are important determinants of adverse events for many important adverse events associated with drug therapy in children. While this research has been difficult to conduct over the past decade technical and ethical evolution has greatly facilitated the ability of investigators to conduct pharmacogenomic studies in children. Some of this research has already resulted in changes in public policy and clinical practice, for example in the case of codeine use by mothers and children. It is likely that the use of pharmacogenomics to enhance drug safety will first be realized among selected groups of children with high rates of drug use such as children with cancer, but it also likely that this research will be extended to other groups of children who have high rates of drug utilization and as well as providing insights into the mechanisms and pathophysiology of adverse drug reactions in children.

Pharmacogenomics in children

Historically genetics has not been considered when prescribing drugs for children. However, it is clear that genetics are not only an important determinant of disease in children but also of drug response for many important drugs that are core agents used in the therapy of common problems in children. Advances in therapy and in the ethical construct of children's research have made pharmacogenomic assessment for children much easier to pursue. It is likely that pharmacogenomics will become part of the therapeutic decision making process for children, notably in areas such as childhood cancer where the benefits and risks of therapy are considerable.