Considerations in the rational design and conduct of phase I/II pediatric clinical trials: avoiding the problems and pitfalls

Pediatric dosing for locally acting drugs in submissions to the U.S. Food and Drug Administration between 2002 and 2020

Deriving pediatric doses for locally acting drugs (LADs) presents a unique challenge because limited systemic exposure hinders commonly used approaches such as pharmacokinetic matching to adults. This study systematically evaluated drug development practices used for pediatric dose selection of LADs approved by the U.S. Food and Drug Administration from 2002 to 2020. The three study objectives were: (1) to determine the dose selection approach for the labeled pediatric dose, (2) to examine the studied pediatric dose(s), and (3) to evaluate the characteristics of the pediatric clinical programs used to support the labeled pediatric dose. A total of 187 pediatric submissions were characterized for the labeled and studied pediatric doses of LADs. The pediatric dose was predominantly labeled as a flat dose (91%) and at a single-dose level (67%) similar to adults. The majority (68.4%) of the submissions had the same labeled dose for pediatrics and adults. Independent pharmacodynamic/efficacy studies in pediatric patients commonly (64.2%) provided supportive evidence for the labeled pediatric dose. Inhalation, nasal, and injectable submissions had the highest number of clinical trials, lowest usage of an extrapolation of efficacy approach, and utilized diverse approaches in selecting the studied pediatric doses. This article highlights approaches for LAD dosing in pediatric patients and can be used to inform drug development of these products in the pediatric population.

Recent oncolytic virotherapy clinical trials outline a roadmap for the treatment of high-grade glioma

Adult and pediatric high-grade gliomas (HGGs) are aggressive cancers of the central nervous system that confer dismal clinical prognoses. Standard radiation and chemotherapy have demonstrated only limited efficacy in HGGs, motivating the accelerated investigation of novel modalities such as oncolytic virus (OV) therapies. OV centered therapies work through a mixed mechanism centered on oncolysis and the stimulation of an antitumor immune response. Three recent clinical trials utilizing herpes simplex virus-1 and adenovirus-based oncolytic virotherapy demonstrated not only the safety and efficacy of OVs but also novel dosing strategies that augment OV response potential. Considering these recent trials, herein we present a roadmap for future clinical trials of oncolytic immunovirotherapy in both adult and pediatric HGG, as well as persistent roadblocks related to the assessment of OV efficacy within and between trials.

Off-Label, but on-Evidence? A Review of the Level of Evidence for Pediatric Pharmacotherapy

Many drugs are still prescribed off-label to the pediatric population. Although off-label drug use not supported by high level of evidence is potentially harmful, a comprehensive overview of the quality of the evidence pertaining off-label drug use in children is lacking. The Dutch Pediatric Formulary (DPF) provides best evidence-based dosing guidelines for drugs used in children. For each drug-indication-age group combination-together compiling one record-we scored the highest available level of evidence: labeled use, systematic review or meta-analysis, randomized controlled trial (RCT), comparative research, noncomparative research, or consensus-based expert opinions. For records based on selected guidelines, the original sources were not reviewed. These records were scored as guideline. A total of 774 drugs were analyzed comprising a total of 6,426 records. Of all off-label records (n = 2,718), 14% were supported by high quality evidence (4% meta-analysis or systematic reviews, 10% RCTs of high quality), 20% by comparative research, 14% by noncomparative research, 37% by consensus-based expert opinions, and 15% by selected guidelines. Fifty-eight percent of all records were authorized, increasing with age from 30% in preterm neonates (n = 110) up to 64% in adolescents (n = 1,630). Many have advocated that off-label use is only justified when supported by a high level of evidence. We show that this prerequisite would seriously limit available drug treatment for children as the underlying evidence is low across ages and drug classes. Our data identify the drugs and therapeutic areas for which evidence is clearly missing and could drive the global research agenda.

Development of a pediatric physiologically-based pharmacokinetic model to support recommended dosing of atezolizumab in children with solid tumors

Background: Atezolizumab has been studied in multiple indications for both pediatric and adult patient populations. Generally, clinical studies enrolling pediatric patients may not collect sufficient pharmacokinetic data to characterize the drug exposure and disposition because of operational, ethical, and logistical challenges including burden to children and blood sample volume limitations. Therefore, mechanistic modeling and simulation may serve as a tool to predict and understand the drug exposure in pediatric patients.

Objective: To use mechanistic physiologically-based pharmacokinetic (PBPK) modeling to predict atezolizumab exposure at a dose of 15 mg/kg (max 1,200 mg) in pediatric patients to support dose rationalization and label recommendations.

Methods: A minimal mechanistic PBPK model was used which incorporated age-dependent changes in physiology and biochemistry that are related to atezolizumab disposition such as endogenous IgG concentration and lymph flow. The PBPK model was developed using both in vitro data and clinically observed data in adults and was verified across dose levels obtained from a phase I and multiple phase III studies in both pediatric patients and adults. The verified model was then used to generate PK predictions for pediatric and adult subjects ranging from 2- to 29-year-old.

Results: Individualized verification in children and in adults showed that the simulated concentrations of atezolizumab were comparable (76% within two-fold and 90% within three-fold, respectively) to the observed data with no bias for either over- or under-prediction. Applying the verified model, the predicted exposure metrics including C_min, C_max, and AUC_tau were consistent between pediatric and adult patients with a geometric mean of pediatric exposure metrics between 0.8- to 1.25-fold of the values in adults.

Conclusion: The results show that a 15 mg/kg (max 1,200 mg) atezolizumab dose administered intravenously in pediatric patients provides comparable atezolizumab exposure to a dose of 1,200 mg in adults. This suggests that a dose of 15 mg/kg will provide adequate and effective atezolizumab exposure in pediatric patients from 2- to 18-year-old.

Informed consent and assent guide for paediatric clinical trials in Europe

OBJECTIVE

Clinical trial sponsors spend considerable resources preparing informed consent (IC) and assent documentation for multinational paediatric clinical trial applications in Europe due to the limited and dispersed patient populations, the variation of national legal and ethical requirements, and the lack of detailed guidance. The aim of this study was to design new easy-to-use guide publicly available on European Medicines Agency's, Enpr-EMA website for all stakeholders.

METHODS

Current EU legal, ethical and regulatory guidance for paediatric clinical trials were collated, analysed and divided into 30 subject elements in two tables. The European Network of Young Person's Advisory Group reviewed the data and provided specific comments. A three-level recommendation using 'traffic light' symbols was designed for four age groups of children, according to relevance and the requirements.

RESULTS

A single guide document includes two tables: (1) general information and (2) trial-specific information. In the age group of 6-9 years old, 92% of the trial-specific subject elements can be or should be included in the IC discussion. Even in the youngest possible age group (2-5 years old children), the number of elements considered was, on average, 52%.

CONCLUSION

The EU Clinical Trial Regulation (2014) does not contain specific requirements exclusively for paediatric clinical trials. This work is the first to extensively collate all the current legal, regulatory and ethical documentation on the IC process, together with input from adolescents. This guide may increase the ethical standards in paediatric clinical trials.

Special issues raised by evolving areas of clinical research

Each study presents its own set of ethical considerations. Certain kinds of ethical issues are inherent in particular areas of clinical research, regardless of specific ethical questions associated with a specific study. In this chapter, some of the most common special areas of clinical research are presented, highlighting the ethical issues most frequently associated with each.

How to Conduct Clinical Trials in Children: A Tutorial

Despite a growing interest in, and commitment to, implementing pediatric clinical trials, approximately one in every five trials in children fails because of inappropriate study design, suboptimal experiment planning, or inadequate participant enrollment. This tutorial, presented from the perspectives of seasoned pediatric investigators, an experienced research coordinator, and an established pediatric clinical trials network, is designed to provide practical guidance for successfully implementing pediatric clinical trials at an academic center or another comparable institution.

Safety, dosing, and pharmaceutical quality for studies that evaluate medicinal products (including biological products) in neonates

The study of medications among pediatric patients has increased worldwide since 1997 in response to new legislation and regulations, but these studies have not yet adequately addressed the therapeutic needs of neonates. Additionally, extant guidance developed by regulatory agencies worldwide does not fully address the specificities of neonatal drug development, especially among extremely premature newborns who currently survive. Consequently, an international consortium from Canada, Europe, Japan, and the United States was organized by the Critical Path Institute to address the content of guidance. This group included neonatologists, neonatal nurses, parents, regulators, ethicists, clinical pharmacologists, specialists in pharmacokinetics, specialists in clinical trials and pediatricians working in the pharmaceutical industry. This group has developed a comprehensive, referenced White Paper to guide neonatal clinical trials of medicines - particularly early phase studies. Key points include: the need to base product development on neonatal physiology and pharmacology while making the most of knowledge acquired in other settings; the central role of families in research; and the value of the whole neonatal team in the design, implementation and interpretation of studies. This White Paper should facilitate successful clinical trials of medicines in neonates by informing regulators, sponsors, and the neonatal community of existing good practice.

Medicines for Pediatric Patients-Biopharmaceutical, Developmental, and Regulatory Considerations

This commentary reflects current developments in pediatric medicine. The underpinning legislation in both Europe and the United States has led to the initiation of an increased number of clinical trials in the pediatric population, but there are still a number of outstanding issues within this field. These include the differences in the physiology between adults and the very heterogeneous nature of pediatric patients. There is an ongoing scientific debate on the applicability of a Pediatric Biopharmaceutical Classification System to define when waivers for bioequivalence studies can be supported by in vitro dissolution. However, a challenge is that in vitro models should adequately mimic the physiology of different pediatric age-groups and dose definition is another critical aspect. There is a tendency for off-label use of established adult medicines, resulting in increased adverse events and decreased efficacy in the target population. Recent advances in physiologically based pharmacokinetic modelling may be used to provide valuable input into these discussions, but there are currently still many knowledge gaps. It is encouraging that there is a global recognition of these deficiencies and substantial funding in the field of basic research is being provided, for example, within Europe the Innovative Medicines Initiative consortium.

Pharmacokinetic considerations when prescribing in children

Before prescribing, the pediatrician typically considers recommended dosing guidelines and issues related to safety. Rarely does (s)he consider the impact of normal growth and development on drug disposition and by extension drug action. This paper reviews how the processes of absorption, distribution, metabolism and elimination differ between healthy children and adults and briefly discusses considerations for medication prescribing in children where these processes are altered secondary to comorbidities.

Single-dose pharmacokinetics and safety of azilsartan medoxomil in children and adolescents with hypertension as compared to healthy adults

PURPOSE

This open-label, multicenter, single-dose study characterized the pharmacokinetics and short-term safety of azilsartan medoxomil (AZL-M) in hypertensive pediatric subjects (12-16 years [cohort 1a; n = 9]; 6-11 years [cohort 2; n = 8]; 4-5 years [cohort 3; n = 3]).

METHODS

Model-based simulations were performed to guide dosing, especially in 1-5-year olds, who were difficult to enroll. AZL-M was dosed according to body weight (20-60-mg tablet, cohorts 1a and 2; 0.66 mg/kg granule suspension, cohort 3). In cohort 1, gender-matched healthy adults (cohort 1b; n = 9) received AZL-M 80 mg.

RESULTS

Exposure to AZL (active moiety of AZL-M), measured by dose-/body weight-normalized C max and AUC0-∞, was ∼15-30 % lower in pediatric subjects versus adults. In simulations, exposure with 0.66 mg/kg AZL-M in pediatric subjects weighing 8-25 kg approximated to AZL-M 40 mg (typical starting dose) in adults. The simulations suggest that 25-50-kg subjects require half the adult dose (10-40 mg), whereas 50-100-kg subjects can use the same dosing as adults. Adverse events were mild in intensity, apart from one moderate event (migraine).

CONCLUSIONS

This dosing strategy should be safe in pediatric patients, as AZL exposure would not exceed that seen in adults with the highest approved AZL-M dose (80 mg).

Safety, Pharmacokinetics and Efficacy of Dolutegravir in Treatment-experienced HIV-1 Infected Adolescents: Forty-eight-week Results from IMPAACT P1093

OBJECTIVE

To assess the pharmacokinetics (PK), safety and efficacy of dolutegravir plus optimized background regimen in HIV-infected treatment-experienced adolescents.

METHODS

Children older than 12 to younger than 18 years received dolutegravir weight-based fixed doses at approximately 1.0 mg/kg once daily in a phase I/II multicenter open label 48-week study. Intensive PK evaluation was done at steady state after dolutegravir was added to a failing regimen or started at the end of a treatment interruption. Safety and HIV RNA and CD4 cell count assessments were performed through week 48.

RESULTS

Twenty-three adolescents were enrolled and 22 (96%) completed the 48-week study visit. Median age and weight were 15 years and 52 kg, respectively. Median [interquartile range (IQR)] baseline CD4+ cell count was 466 cells/μL (297, 771). Median (IQR) baseline HIV-1 RNA log10 was 4.3 log10 copies/mL (3.9, 4.6). Dolutegravir geometric mean of the area under the plasma concentration-time curve from time of administration to 24 hours after dosing (AUC0-24) and 24 hour postdose concentration (C24) were 46.0 μg hours/mL and 0.90 μg/mL, respectively, which were within the study targets based on adult PK ranges. Virologic success with an HIV RNA <400 copies/mL was achieved in 74% [95% confidence interval (CI): 52-90%] at week 48. Additionally, 61% (95% CI: 39-80%) had an HIV RNA <50 copies/mL at week 48. Median (IQR) gain in CD4 cell count at week 48 was 84 cells/μL (-81, 238). Dolutegravir was well tolerated, with no grade 4 adverse events, serious adverse events or discontinuations because of serious adverse events.

CONCLUSIONS

Dolutegravir achieved target PK exposures in adolescents. Dolutegravir was safe and well tolerated, providing good virologic efficacy through week 48.

Observational infant exploratory [(14)C]-paracetamol pharmacokinetic microdose/therapeutic dose study with accelerator mass spectrometry bioanalysis

AIMS

The aims of the study were to compare [(14)C]-paracetamol ([(14)C]-PARA) paediatric pharmacokinetics (PK) after administration mixed in a therapeutic dose or an isolated microdose and to develop further and validate accelerator mass spectrometry (AMS) bioanalysis in the 0-2 year old age group.

METHODS

[(14)C]-PARA concentrations in 10-15 µl plasma samples were measured after enteral or i.v. administration of a single [(14)C]-PARA microdose or mixed in with therapeutic dose in infants receiving PARA as part of their therapeutic regimen.

RESULTS

Thirty-four infants were included in the PARA PK analysis for this study: oral microdose (n = 4), i.v. microdose (n = 6), oral therapeutic (n = 6) and i.v. therapeutic (n = 18). The respective mean clearance (CL) values (SDs in parentheses) for these dosed groups were 1.46 (1.00) l h(-1), 1.76 (1.07) l h(-1), 2.93 (2.08) l h(-1) and 2.72 (3.10) l h(-1), t(1/2) values 2.65 h, 2.55 h, 8.36 h and 7.16 h and dose normalized AUC(0-t) (mg l(-1) h) values were 0.90 (0.43), 0.84 (0.57), 0.7 (0.79) and 0.54 (0.26).

CONCLUSIONS

All necessary ethical, scientific, clinical and regulatory procedures were put in place to conduct PK studies using enteral and systemic microdosing in two European centres. The pharmacokinetics of a therapeutic dose (mg kg(-1)) and a microdose (ng kg(-1)) in babies between 35 to 127 weeks post-menstrual age. [(14)C]-PARA pharmacokinetic parameters were within a two-fold range after a therapeutic dose or a microdose. Exploratory studies using doses significantly less than therapeutic doses may offer ethical and safety advantages with increased bionalytical sensitivity in selected exploratory paediatric pharmacokinetic studies.

Special populations and pharmacogenetic issues in tuberculosis drug development and clinical research

Special populations, including children and pregnant women, have been neglected in tuberculosis drug development. Patients in developing countries are inadequately represented in pharmacology research, and postmarketing pharmacovigilance activities tend to be rudimentary in these settings. There is an ethical imperative to generate evidence at an early stage to support optimal treatment in these populations and in populations with common comorbid conditions, such as diabetes and human immunodeficiency virus (HIV) infection. This article highlights the research needed to support equitable access to new antituberculosis regimens. Efficient and opportunistic pharmacokinetic study designs, typically using sparse sampling and population analysis methods, can facilitate optimal dose selection for children and pregnant women. Formulations suitable for children should be developed early and used in pharmacokinetic studies to guide dose selection. Drug-drug interactions between commonly coprescribed medications also need to be evaluated, and when these are significant, alternative approaches should be sought. A potent rifamycin-sparing regimen could revolutionize the treatment of adults and children requiring a protease inhibitor as part of antiretroviral treatment regimens for HIV infection. A sufficiently wide formulary of drugs should be developed for those with contraindications to the standard approaches. Because genetic variations may influence an individual's response to tuberculosis treatment, depending on the population being treated, it is important that samples be collected and stored for pharmacogenetic study in future clinical trials.

Clinical trials in children

Safety and efficacy data on many medicines used in children are surprisingly scarce. As a result children are sometimes given ineffective medicines or medicines with unknown harmful side effects. Better and more relevant clinical trials in children are needed to increase our knowledge of the effects of medicines and to prevent the delayed or non-use of beneficial therapies. Clinical trials provide reliable evidence of treatment effects by rigorous controlled testing of interventions on human subjects. Paediatric trials are more challenging to conduct than trials in adults because of the paucity of funding, uniqueness of children and particular ethical concerns. Although current regulations and initiatives are improving the scope, quantity and quality of trials in children, there are still deficiencies that need to be addressed to accelerate radically equitable access to evidence-based therapies in children.

Changes in individual drug-independent system parameters during virtual paediatric pharmacokinetic trials: introducing time-varying physiology into a paediatric PBPK model

Although both POPPK and physiologically based pharmacokinetic (PBPK) models can account for age and other covariates within a paediatric population, they generally do not account for real-time growth and maturation of the individuals through the time course of drug exposure; this may be significant in prolonged neonatal studies. The major objective of this study was to introduce age progression into a paediatric PBPK model, to allow for continuous updating of anatomical, physiological and biological processes in each individual subject over time. The Simcyp paediatric PBPK model simulator system parameters were reanalysed to assess the impact of re-defining the individual over the study period. A schedule for re-defining parameters within the Simcyp paediatric simulator, for each subject, over a prolonged study period, was devised to allow seamless prediction of pharmacokinetics (PK). The model was applied to predict concentration-time data from multiday studies on sildenafil and phenytoin performed in neonates. Among PBPK system parameters, CYP3A4 abundance was one of the fastest changing covariates and a 1-h re-sampling schedule was needed for babies below age 3.5 days in order to seamlessly predict PK (<5% change in abundance) with subject maturation. The re-sampling frequency decreased as age increased, reaching biweekly by 6 months of age. The PK of both sildenafil and phenytoin were predicted better at the end of a prolonged study period using the time varying vs fixed PBPK models. Paediatric PBPK models which account for time-varying system parameters during prolonged studies may provide more mechanistic PK predictions in neonates and infants.

Limited impact of EU paediatric regulation on Finnish clinical trials highlights need for Nordic collaboration

The Finnish Investigators Network for Paediatric Medicines (FINPEDMED) was established in 2007, to meet the expected increase in paediatric clinical trials following the new EU Paediatric Regulation. Between 2007 and 2012, FINPEDMED received 91 trial requests, 18 trials were started, and in 24 cases, Finnish investigators were not selected by sponsors.

CONCLUSION

This experience from Finland highlights the need for Nordic collaboration to increase expertise, recruitment base and attractiveness for sponsors.

Early-phase clinical trials in the community: results from the national cancer institute community cancer centers program early-phase working group baseline assessment

PURPOSE

The National Cancer Institute (NCI) Community Cancer Centers Program (NCCCP) formed an Early-Phase Working Group to facilitate site participation in early-phase (EP) trials. The Working Group conducted a baseline assessment (BA) to describe the sites' EP trial infrastructure and its association with accrual.

METHODS

EP accrual and infrastructure data for the sites were obtained for July 2010-June 2011 and 2010, respectively. Sites with EP accrual rates at or above the median were considered high-accruing sites. Analyses were performed to identify site characteristics associated with higher accrual onto EP trials.

RESULTS

Twenty-seven of the 30 NCCCP sites participated. The median number of EP trials open per site over the course of July 2010-June 2011 was 19. Median EP accrual per site was 14 patients in 1 year. Approximately half of the EP trials were Cooperative Group; most were phase II. Except for having a higher number of EP trials open (P = .04), high-accruing sites (n = 14) did not differ significantly from low-accruing sites (n = 13) in terms of any single site characteristic. High-accruing sites did have shorter institutional review board (IRB) turnaround time by 20 days, and were almost three times as likely to be a lead Community Clinical Oncology Program site (small sample size may have prevented statistical significance). Most sites had at least basic EP trial infrastructure.

CONCLUSION

Community cancer centers are capable of conducting EP trials. Infrastructure and collaborations are critical components of success. This assessment provides useful information for implementing EP trials in the community.

Pediatric high grade glioma: a review and update on tumor clinical characteristics and biology

High grade gliomas (HGG) are one of the most common central nervous system (CNS) tumors encountered in adults, but they only represent approximately 8–12% of all pediatric CNS tumors. Historically, pediatric HGG were thought to be similar to adult HGG since they appear histologically identical; however, molecular, genetic, and biologic data reveal that they are distinct. Similar to adults, pediatric HGG are very aggressive and malignant lesions with few patients achieving long-term survival despite a variety of therapies. Initial treatment strategies typically consist of a gross total resection (GTR) when feasible followed by focal radiotherapy combined with chemotherapy. Over the last few decades, a wealth of data has emerged from basic science and pre-clinical animal models helping to better define the common biologic, genetic, and molecular make-up of these tumors. These data have not only provided a better understanding of tumor biology, but they have also provided new areas of research targeting molecular and genetic pathways with the potential for novel treatment strategies and improved patient outcomes. Here we provide a review of pediatric non-brainstem HGG, including epidemiology, presentation, histology, imaging characteristics, treatments, survival outcomes, and an overview of both basic and translational research. An understanding of all relevant pre-clinical tumor models, including their strengths and pitfalls is essential in realizing improved patient outcomes in this population.

Characteristics and quality of reporting of cluster randomized trials in children: reporting needs improvement

OBJECTIVE

To describe the characteristics and quality of reporting of cluster randomized trials (CRTs) in children published from 2004 to 2010.

STUDY DESIGN AND SETTING

Four databases were searched for reports of CRTs in children (0-18 years). Characteristics of the studies were summarized and the quality of reporting assessed using consolidated standards of reporting trial-CRT (CONSORT-CRT).

RESULTS

Of 1,949 identified references, 106 were included. The number of published CRTs in children increased since 2004. The greatest proportion of CRTs was undertaken in Europe (29%), whereas 40% was conducted in low- and middle-income countries. Most studies were of complex rather than simple interventions (83%); were preventive rather than treatment interventions (76%); and most frequently addressed infectious disease (21%), diet/physical activity interventions (19%), health-risk behaviors (15%), and undernutrition (13%). The majority used schools as units of randomization (72%) and enrolled 1,000-10,000 children per study (51%). Reporting was generally poor, with 34% of CRTs inadequately reporting on more than half of the CONSORT-CRT criteria. Although 85% of CRTs reported that they had ethics approval for the study, consent or assent was not obtained from children in most studies.

CONCLUSION

Children-specific elements of reporting are needed to improve the quality of reporting of CRTs and consequently their planning and implementation.

Evaluation of drug formularies for pediatric intensive care

OBJECTIVES

To evaluate availability and reliability of pediatric drug dosing guidelines in selected formularies for intensive care patients. Most drugs used in the pediatric intensive care unit are prescribed off-label, often on the guidance of limited information from commonly used drug formularies.

DESIGN

Availability of dosing information on prescribed drugs in a Dutch intensive care unit from January 1, 2005 to December 31, 2006 was compared among four selected formularies (Micromedex, Lexi-Comp, Drug Formulary for Children, Drug Doses). Reliability of dosing guidelines was assessed by evaluating labeling status and literature data for the three most (midazolam, acetaminophen, and amoxicillin/clavulanic acid) and the three least (bosentan, ketanserin, and iloprost) prescribed drugs.

MEASUREMENTS AND MAIN RESULTS

The selected formularies covered 68% to 86% of all 257 prescribed drugs. Guidelines differ widely on daily doses per kilogram, dose description, dosing regimen, and age ranges. For the three most prescribed and one of the least prescribed drugs (bosentan), dosing guidelines adequately reflected labeling status and existing (but scarce) literature. No dosing guidelines were available for iloprost, and only one dosing guideline was available for ketanserin.

CONCLUSIONS

This study shows that four commonly used drug formularies give few and widely differing dosing guidelines for drugs prescribed in the intensive care unit. If guidelines exist, they seem to reflect labeling status (if present) and limited literature available. Findings from this study likely reflect the scarcity of drug studies in this population. Physicians should be aware of the limitations of these formularies for daily practice in this group of vulnerable patients.

Bayesian design using adult data to augment pediatric trials

BACKGROUND

It can be difficult to conduct pediatric clinical trials because there is often a low incidence of the disease in children, making accrual slow or infeasible. In addition, low mortality and morbidity in this population make it impractical to achieve adequate power. In this case, the only evidence for treatment efficacy comes from adult trials. Since pediatric care providers are accustomed to relying on evidence from adult studies, it is natural to consider borrowing information from adult trials.

PURPOSE

The goal of this article is to propose a Bayesian approach to the design and analysis of pediatric trials to allow borrowing strength from previous or simultaneous adult trials.

METHODS

We apply a hierarchical model for which the efficacy parameter from the adult trial and that of the pediatric trail are considered to be draws from a normal distribution. The choice of (the variance of) this distribution is guided by discussion with medical experts. We show that with this information, one can calculate the sample size required for the pediatric trial. We discuss how inference of these studies in pediatric populations depends on the parameter that captures the similarity of the treatment efficacy in adults compared to children.

RESULTS

The Bayesian approach can substantially increase the power of a pediatric clinical trial (or equivalently decrease the number of subjects required) by formally leveraging the data from the adult trial.

LIMITATIONS

Our method relies on obtaining a value for the inter-study variability, nu, which may be difficult to describe to a clinical investigator.

CONCLUSIONS

The Bayesian approach has the potential of making pediatric clinical trials feasible because it has the effect of borrowing strength from adult trials, thus requiring a smaller pediatric trial to show efficacy of a drug in children.

Application of optimal design methodologies in clinical pharmacology experiments

Pharmacokinetics and pharmacodynamics data are often analysed by mixed-effects modelling techniques (also known as population analysis), which has become a standard tool in the pharmaceutical industries for drug development. The last 10 years has witnessed considerable interest in the application of experimental design theories to population pharmacokinetic and pharmacodynamic experiments. Design of population pharmacokinetic experiments involves selection and a careful balance of a number of design factors. Optimal design theory uses prior information about the model and parameter estimates to optimize a function of the Fisher information matrix to obtain the best combination of the design factors. This paper provides a review of the different approaches that have been described in the literature for optimal design of population pharmacokinetic and pharmacodynamic experiments. It describes options that are available and highlights some of the issues that could be of concern as regards practical application. It also discusses areas of application of optimal design theories in clinical pharmacology experiments. It is expected that as the awareness about the benefits of this approach increases, more people will embrace it and ultimately will lead to more efficient population pharmacokinetic and pharmacodynamic experiments and can also help to reduce both cost and time during drug development.

Impact of the CYP2C19*17 allele on the pharmacokinetics of omeprazole and pantoprazole in children: evidence for a differential effect

The impact of the CYP2C19*17 allele on the pharmacokinetics of pantoprazole and omeprazole in previously studied children (n = 40) was explored. When pantoprazole area under the plasma concentration versus time curve (AUC) was examined as a function of CYP2C19 genotype, a significantly lower AUC was observed for subjects identified as CYP2C19*1/*1 and *1/*17. For pantoprazole, a statistically significant relationship was observed between CYP2C19 genotype and both dose-corrected AUC (p < 0.0001) and the apparent elimination rate constant (K(el); p = 0.0012); no significant genotype-phenotype relationships were observed for omeprazole.

Ontogeny of midazolam glucuronidation in preterm infants

Purpose

In preterm infants, the biotransformation of midazolam (M) to 1-OH-midazolam (OHM) by cytochrome P450 3A4 (CYP3A4) is developmentally immature, but it is currently unknown whether the glucuronidation of OHM to 1-OH-midazolam glucuronide (OHMG) is also decreased. The aim of our study was to investigate the urinary excretion of midazolam and its metabolites OHM and OHMG in preterm neonates following the intravenous (IV) or oral (PO) administration of a single M dose.

Methods

Preterm infants (post-natal age 3–13 days, gestational age 26–34 4/7 weeks) scheduled to undergo a stressful procedure received a 30-min IV infusion (n = 15) or a PO bolus dose (n= 7) of 0.1 mg/kg midazolam. The percentage of midazolam dose excreted in the urine as M, OHM and OHMG up to 6 h post-dose was determined.

Results

The median percentage of the midazolam dose excreted as M, OHM and OHMG in the urine during the 6-h interval after the IV infusion was 0.44% (range 0.02–1.39%), 0.04% (0.01–0.13%) and 1.57% (0.36–7.7%), respectively. After administration of the PO bolus dose, the median percentage of M, OHM and OHMG excreted in the urine was 0.11% (0.02–0.59%), 0.02% (0.00–0.10%) and 1.69% (0.58–7.31%), respectively. The proportion of the IV midazolam dose excreted as OHMG increased significantly with postconceptional age (r = 0.73, p < 0.05).

Conclusion

The glucuronidation of OHM appears immature in preterm infants less than 2 weeks of age. The observed increase in urinary excretion of OHMG with postconceptional age likely reflects the combined maturation of glucuronidation and renal function.

Stability of Sunitinib in Oral Suspension

Background:

Sunitinib Is a novel, oral, multitargeted tyrosine kinase Inhibitor with antiangiogenic and antitumor activity. No liquid formulation of sunitinib malate is commercially available for pediatric administration.

Objective:

To prepare extemporaneously an oral liquid formulation of sunitinib malate from commercially available capsules and study its chemical and physical stability in suspension at room temperature and under refrigeration at 4 °C.

Methods:

Six Independent samples were prepared by mixing the contents of 3 sunitinib malate capsules (each equivalent to 50 mg of sunitinib) with 15 mL of a 1:1 mixture of Ora-Plus; Ora-Sweet solution to yield a final concentration of 10 mg/mL Suspensions were stored in amber plastic bottles with child-resistant caps. Three samples were refrigerated at 4 °C and 3 were stored at room temperature. Aliquots from each bottle were obtained on days 1, 2, 3, 5, 7, 14, 21, 30, and 60 and diluted to a final concentration of 300 ng/mL with 500 ng/mL of clozapine in 50% acetonttrile. Sunitinib concentrations were then measured by a liquid chromatography–tandem mass spectrometry assay validated in our laboratory.

Results:

At room temperature and under refrigeration at 4 °C, sunitinib in a 10-mg/mL suspension of sunitinib malate with Ora-Plus:Ora-Sweet 1:1 maintained greater than 96% of its initial concentration for 60 days, Visual appearance (color and consistency) and odor of drug suspension remained unchanged during the study.

Conclusions:

Sunitinib is stable in an oral suspension prepared from commercially available capsules for at least 60 days al room temperature and refrigeration at 4 °C. This liquid formulation is better suited for administration to children and adults with cancer who cannot swallow sunitinib capsules.

Important issues in the design and reporting of clinical trials in severe sepsis and acute lung injury

Severe sepsis and acute lung injury are challenging diagnoses as they relate to designing and reporting of clinical trials. The limited success in bringing forward new therapies in these areas is likely proof of that premise. The ability to use preclinical and phase I and II trial data to predict which patients and which dosing regimens are more likely to benefit is perhaps the greatest challenge. Animal models continue to be refined in attempts to more accurately reproduce human sepsis and acute lung injury. Oncology research should serve as a model for optimizing the integration of pharmacodynamics and pharmacogenetics into trial design. The European Organization for Research and Treatment of Cancer provides a valuable template for nonfunded multicenter clinical trial success. The marked heterogeneity of the patient population and small signal (tested therapy)-to-noise (comorbidities) ratio makes identification of treatment effect difficult. Dedicated investigators still enroll ineligible patients who are included in intent to treat analysis. High enrolling centers create less problems in an adequate test of a new therapy. Much has been learned from negative trials as to value of post hoc subgroup and interim analyses. Debate continues on fair and appropriate end point of trials. Extrapolation of adult positive trial results to children is problematic. Conflict of interest issues which rested dormantly for years are now at the forefront of discussion, and journal editorial board responsibility in this area is being recognized. Protocols may also help reduce heterogeneity of treatment across centers in clinical trials. This article reviews many of the problems encountered in clinical trial design and reporting and offers a perspective on dealing with them to the betterment of a clinical trial.