The Path to Perfect Pediatric Posology - Drug Development in Pediatrics

Proof of concept of physiologically based pharmacokinetic modelling in paediatric acute lymphoblastic leukaemia

Physiologically based pharmacokinetic (PBPK) modelling is an alternative modelling technique that is increasingly used in pharmacokinetics. Due to its nature, it can be complementarily employed to population pharmacokinetics, especially when it comes to small population size. Here, we report the proof of concept of its application to accurately describe the pharmacokinetics of a recombinant L-asparaginase in paediatric patients with acute lymphoblastic leukaemia. Data from two randomized, double-blind, phase II/III clinical studies (MC-ASP.4/ALL; MC-ASP.5/ALL) were included to setup and evaluate the final model, respectively. Final population values for basic pharmacokinetic parameters were calculated (clearance: 0.0569 L/h/19.5 kg, volume of distribution: 1.251 L, half-life: 18.5 h, trough concentration: 140.9 IU/L). Pharmacokinetic parameter prediction as well as predictive performance of the model proofed to be comparable to a separately developed population pharmacokinetic model with 13% deviation in predicted median L-asparaginase trough levels. To the best of our knowledge, this is the first whole-body PBPK model of a non-antibody therapeutic protein.

A Validated HPLC-Diode Array Detection Method for Therapeutic Drug Monitoring of Thiopurines in Pediatric Patients: From Bench to Bedside

Thiopurine drugs are part of the therapeutic armamentarium for pediatric patients suffering from inflammatory bowel disease (IBD) and acute lymphoblastic leukemia (ALL). The therapeutic drug monitoring of these drugs, consisting of measurements of the thiopurine metabolites thioguanine nucleotides (TGN) and methylmercaptopurine nucleotides (MMPN) are used to optimize the effectiveness of treatment and prevent adverse effects. In this context, we developed and validated a high-performance liquid chromatography-diode array detection (HPLC-DAD) method for the simultaneous quantification of thiopurine metabolites according to the most recent International Council for Harmonisation (ICH) guidelines. The calibration curves were built in the clinically relevant range of concentrations for TGN of 300-12,000 nM and for MMPN of 3000-60,000 nM. The limit of detection and the lower limit of quantification were 100 and 300 nM for TGN and 900 and 3000 nM for MMPN, respectively. The percentage of inter-day accuracy and precision (CV%) varied between 85 and 104% and 1.6 and 13.8%. Stability was demonstrated for both of the metabolites for at least 50 days at -20 °C. The proposed HPLC-DAD method showed an appropriate selectivity, specificity, linearity, accuracy, precision and good applicability to samples from patients with IBD and ALL undergoing thiopurine treatment.

Pediatric Clinical Research Networks: Role in Accelerating Development of Therapeutics in Children

Background

Recent decades have seen many advances in policy and legislation that support the development of drugs used by neonates, infants, children, and young people. This review summarizes the characteristics and performance of networks capable of conducting studies needed to meet regulatory requirements and make advances in pediatric drug development.

Methods

Description of network goals and capabilities by network leaders.

Results

In the United States, Europe, Japan, and Canada, clinical research networks have been organized to meet the needs of biopharmaceutical and academic sponsors for timely access to high-quality sites, as well as to provide advice about drug development with regard to strategic and operational feasibility. Each network addresses the specificities of its context while working toward shared principles including standards and timelines; alignment of goals and processes, while not disturbing arrangements for conducting trials that work well; wide geographic coverage; all age groups and pediatric conditions; sources of funding; sites that compete on performance; performance monitoring for benchmarking, and opportunities to optimize the allocation of resources; and education and training for network members. Facilitation in interactions among these networks is based on a single point-of-contact for each; similar approaches to strategic and operational feasibility assessment, and site selection; and collaborative approaches to education and training.

Conclusion

Within five years, clinical research networks will support the needs of biopharmaceutical and publicly funded pediatric drug development through locally appropriate and globally interoperable approaches.

Protocol for the Vitamin D Oral Replacement in Asthma (VDORA) study

Obesity and asthma are epidemic in the United States and obesity is an independent risk factor for asthma. Low vitamin D levels (i.e. serum 25-hydroxyvitamin D) have been reported in patients with reduced lung function, more frequent respiratory infections, and asthma exacerbations. Experts have proposed that serum levels > 40 ng/mL are required to offer the immunomodulatory benefits of vitamin D. Low vitamin D levels are common in both obesity and asthma, but it is not known whether supplementation with vitamin D improves asthma symptoms. Guidance for drug development stresses the importance of early phase studies to establish accurate population pharmacokinetics (PK) and drug dosing prior to larger phase 3 trials. The PK of this fat-soluble vitamin in children with increased adiposity are unknown; as are the doses need to reach proposed immunomodulatory levels. The objective of this study is to characterize the PK of vitamin D in children with obesity. Children ages 6--18 years who had physician diagnosed asthma and a body mass index (BMI) >85th percentile will be randomized to receive either standard daily dosing or loading doses followed by standard daily dosing. Blood samples will be obtained to characterize the PK of vitamin D. The results of this study will be used to identify a sufficient dose of vitamin D supplement to raise serum levels above a pre-specified value that may result in anti-inflammatory actions that could improve asthma symptoms.

Catching Them Early: Framework Parameters and Progress for Prenatal and Childhood Application of Advanced Therapies

Advanced therapy medicinal products (ATMPs) are medicines for human use based on genes, cells or tissue engineering. After clear successes in adults, the nascent technology now sees increasing pediatric application. For many still untreatable disorders with pre- or perinatal onset, timely intervention is simply indispensable; thus, prenatal and pediatric applications of ATMPs hold great promise for curative treatments. Moreover, for most inherited disorders, early ATMP application may substantially improve efficiency, economy and accessibility compared with application in adults. Vindicating this notion, initial data for cell-based ATMPs show better cell yields, success rates and corrections of disease parameters for younger patients, in addition to reduced overall cell and vector requirements, illustrating that early application may resolve key obstacles to the widespread application of ATMPs for inherited disorders. Here, we provide a selective review of the latest ATMP developments for prenatal, perinatal and pediatric use, with special emphasis on its comparison with ATMPs for adults. Taken together, we provide a perspective on the enormous potential and key framework parameters of clinical prenatal and pediatric ATMP application.

Extending the Reach of Antimicrobial Stewardship to Pediatric Patients

Guidance for developing and implementing antimicrobial stewardship programs for children is lacking. This review article describes unique considerations for planning antimicrobial management of children that may impact stewardship strategies. A variety of methods and training tools are described along with metrics specific to measuring antibiotic use and outcomes in children. Handshake stewardship is specifically explained and is considered a best practice. Information on stewardship in unique settings, including the neonatal intensive care unit and outpatient settings, are included.

A Proof of Concept of the Role of TDM-Based Clinical Pharmacological Advices in Optimizing Antimicrobial Therapy on Real-Time in Different Paediatric Settings

Introduction: Antimicrobial treatment is quite common among hospitalized children. The dynamic age-associated physiological variations coupled with the pathophysiological alterations caused by underlying illness and potential drug-drug interactions makes the implementation of appropriate antimicrobial dosing extremely challenging among paediatrics. Therapeutic drug monitoring (TDM) may represent a valuable tool for assisting clinicians in optimizing antimicrobial exposure. Clinical pharmacological advice (CPA) is an approach based on the correct interpretation of the TDM result by the MD Clinical Pharmacologist in relation to specific underlying conditions, namely the antimicrobial susceptibility of the clinical isolate, the site of infection, the pathophysiological characteristics of the patient and/or the drug-drug interactions of cotreatments. The aim of this study was to assess the role of TDM-based CPAs in providing useful recommendations for the real-time personalization of antimicrobial dosing regimens in various paediatric settings. Materials and methods: Paediatric patients who were admitted to different settings of the IRCCS Azienda Ospedaliero-Universitaria of Bologna, Italy (paediatric intensive care unit [ICU], paediatric onco-haematology, neonatology, and emergency paediatric ward), between January 2021 and June 2021 and who received TDM-based CPAs on real-time for personalization of antimicrobial therapy were retrospectively assessed. Demographic and clinical features, CPAs delivered in relation to different settings and antimicrobials, and type of dosing adjustments were extracted. Two indicators of performance were identified. The number of dosing adjustments provided over the total number of delivered CPAs. The turnaround time (TAT) of CPAs according to a predefined scale (optimal, <12 h; quasi-optimal, between 12-24 h; acceptable, between 24-48 h; suboptimal, >48 h). Results: Overall, 247 CPAs were delivered to 53 paediatric patients (mean 4.7 ± 3.7 CPAs/patient). Most were delivered to onco-haematological patients (39.6%) and to ICU patients (35.8%), and concerned mainly isavuconazole (19.0%) and voriconazole (17.8%). Overall, CPAs suggested dosing adjustments in 37.7% of cases (24.3% increases and 13.4% decreases). Median TAT was 7.5 h (IQR 6.1-8.8 h). Overall, CPAs TAT was optimal in 91.5% of cases, and suboptimal in only 0.8% of cases. Discussion: Our study provides a proof of concept of the helpful role that TDM-based real-time CPAs may have in optimizing antimicrobial exposure in different challenging paediatric scenarios.

Off-label drug use in neonates and infants in Spain: A five-year observational study

OBJECTIVES

To provide information about the off-label rate of all drug prescriptions in neonates and infants up to 1 year in Spain. Also, to analyse the off-label prescription of medicines under current practice in this age group according to different evidence sources.

STUDY DESIGN

A five-year (2015-2019) exploratory observational study about off-label prescription in neonates and infants (0 to 1 year) at primary health care in Spain. All drug prescriptions in this age group were analysed and classified according to their labelling in off-label or on-label. The drugs prescribed off-label were subsequently reviewed in national formularies and other databases to assess its evidence of use beyond what is recommended in the Summary of Product Characteristics (SmPC).

RESULTS

On average 34.50% of total prescriptions were prescribed off-label according to the SmPC. 17.93% of total prescriptions in neonates and infants up to 1 year old were not based on clinical evidence from SmPC, Pediamécum, BNF or DailyMed. In more than 88% of cases, off-label use was related to the posology section of the SmPC, followed by the therapeutic indications and contraindications sections, in 35.20% and 24.10% of cases, respectively. Almost 13% of off-label drugs were over-the-counter. Salbutamol followed by topical tobramycin and colecalciferol were the drugs most prescribed off-label.

CONCLUSIONS

Off-label use of drugs remains as an important public health concern, especially for neonates and infants up to 1 year, who receive the greatest proportion of off-label prescriptions. The evidence-based off-label prescription is a widespread practice that has shown a stable trend during the 5-year study period providing also a certain extent of flexibility to paediatricians in some therapeutic decisions.

COVID-19 and Treatment and Immunization of Children-The Time to Redefine Pediatric Age Groups is Here

Children are infected with coronavirus disease 2019 (COVID-19) as often as adults, but with fewer symptoms. During the first wave of the COVID-19 pandemic, multisystem inflammatory syndrome (MIS) in children (MIS-C), with symptoms similar to Kawasaki syndrome, was described in young minors testing positive for COVID-19. The United States (US) Centers for Disease Control and Prevention (CDC) defined MIS-C as occurring in <21-year-olds, triggering hundreds of PubMed-listed papers. However, postpubertal adolescents are no longer children biologically; the term MIS-C is misleading. Furthermore, MIS also occurs in adults, termed MIS-A by the CDC. Acute and delayed inflammations can be triggered by COVID-19. The 18th birthday is an administrative not a biological age limit, whereas the body matures slowly during puberty. This blur in defining children leads to confusion regarding MIS-C/MIS-A. United States and European Union (EU) drug approval is handled separately for children, defined as <18-year-olds, ascribing non-existent physical characteristics up to the 18th birthday. This blur between the administrative and the physiological meanings for the term child is causing flawed demands for pediatric studies in all drugs and vaccines, including those against COVID-19. Effective treatment of all conditions, including COVID-19, should be based on actual physiological need. Now, the flawed definition for children in the development of drugs and vaccines and their approval is negatively impacting prevention and treatment of COVID-19 in minors. This review reveals the necessity for redefining pediatric age groups to rapidly establish recommendations for optimal prevention and treatment in minors.

Paediatric Medicines in Europe: The Paediatric Regulation-Is It Time for Reform?

Objectives: In this paper, we investigated the effects of the European Paediatric Regulation (EC) N° 1901/2006 with respect to satisfying the paediatric therapeutic needs, assessed in terms of the increased number of paediatric medicinal products, new therapeutic indications in specific high-need conditions (neonates, oncology, rare disease, etc.) and increased number of paediatric clinical studies supporting the marketing authorisation.

Methods: We analysed the paediatric medicinal products approved by the European Medicines Agency in the period January 2007-December 2019, by collecting the following data: year of approval, active substance, legal basis for the marketing authorisation, type of medicinal product (i.e., chemical, biological, or ATMP), orphan drug status, paediatric indication, Anatomical Therapeutic Chemical code (first-level), number and type of paediatric studies. Data were compared with similar data collected in the period 1996–2006.

Results: In the period January 1996–December 2019, in a total of 1,190 medicinal products and 843 active substances, 34 and 38%, respectively, were paediatric. In the two periods, before and after the Paediatric Regulation implementation, the paediatric/total medicinal products ratio was constant while the paediatric/total active substances ratio decreased. Moreover, excluding generics and biosimilars, a total of 106 and 175 paediatric medicines were granted a new paediatric indication, dosage or age group in the two periods; out of 175, 128 paediatric medicines had an approved Paediatric Investigational Plan. The remaining 47 were approved without an approved Paediatric Investigational Plan, following the provisions of Directive 2001/83/EC and repurposing an off-patent drug. The analysis of the clinical studies revealed that drugs with a Paediatric Investigational Plan were supported by 3.5 studies/drug while drugs without a Paediatric Investigational Plan were supported by only 1.6 studies/drug.

Discussion: This report confirms that the expectations of the European Paediatric Regulation (EC) N° 1901/2006 have been mainly satisfied. However, the reasons for the limited development of paediatric medicines in Europe, should be further discussed, taking advantage of recent initiatives in the regulatory field, such as the Action Plan on Paediatrics, and the open consultation on EU Pharmaceutical Strategy.

Clinical Pharmacokinetics of Enalapril and Enalaprilat in Pediatric Patients-A Systematic Review

Purpose: Enalapril has an established safety and efficacy in adults and is used in hypertension, heart failure, and renal failure. In pediatric patients, enalapril is labeled for children with hypertension and used off label in children with heart failure. The systematic literature search aims to assess the current knowledge about enalapril and its active metabolite enalaprilat pharmacokinetics in children as a basis for dose delineation for pediatric patients with heart failure. Methods: A systematic literature review was performed in the PubMed database using relevant keywords. Dose normalization of relevant pharmacokinetic parameters of the identified studies was done for comparison between different diseases and pediatric age groups. Results: The literature search has resulted in three pediatric pharmacokinetic studies of enalapril out of which Wells et al. reported about children with hypertension and Nakamura et al., and Llyod et al. presented data for pediatric heart failure patients. The area under the curve values of enalaprilat in hypertensive pediatric patients increased with respect to the age groups and showed maturation of body functions with increasing age. Dose normalized comparison with the heart failure studies revealed that although the pediatric heart failure patients of > 20 days of age showed the area under the curve a similar to that of hypertensive patients, two pediatric patients of very early age (<20 days) were presented with 5-6-fold higher area under the curve values. Conclusion: Data related to the pharmacokinetics of enalapril and enalaprilat in hypertensive patients and few data for young heart failure children are available. Comparison of dose normalized exposition of the active metabolite enalaprilat indicated similarities between heart failure and hypertensive patients and a potentially high exposition of premature patients but substantially more pharmacokinetic studies are required to have reliable and robust enalapril as well as enalaprilat exposures especially in pediatric patients with heart failure as a basis for any dose delineation.

Population pharmacokinetics, exposure-safety, and immunogenicity of atezolizumab in pediatric and young adult patients with cancer

BACKGROUND

The iMATRIX-atezolizumab study was a phase I/II, multicenter, open-label study designed to assess the safety and pharmacokinetics of atezolizumab in pediatric and young adult patients. We describe the pharmacokinetics (PK), exposure-safety, and immunogenicity of atezolizumab in pediatric and young adults with metastatic solid tumors or hematologic malignancies enrolled in this study.

METHODS

Patients aged < 18 years (n = 69) received a weight-adjusted dose of atezolizumab (15 mg/kg every 3 weeks [q3w]; maximum 1200 mg); those aged ≥ 18 years (n = 18) received a flat dose (1200 mg q3w). A prior two-compartment intravenous infusion input adult population-PK (popPK) model of atezolizumab was used as a basis to model pediatric data.

RESULTS

A total of 431 atezolizumab serum concentrations from 87 relapse-refractory pediatric and young adult patients enrolled in the iMATRIX-atezolizumab study were used for the popPK analysis. The dataset comprised predominantly patients aged < 18 years, including two infants aged < 2 years, with a wide body weight and age range. The clearance and volume of distribution estimates of atezolizumab were 0.217 L/day and 3.01 L, respectively. Atezolizumab geometric mean trough exposures were ~ 20% lower in pediatric patients versus young adults; this was not clinically meaningful as both groups achieved the target concentration (6 μg/mL). Safety was similar between pediatric and young adult patients with no exposure-safety relationship observed. Limited responses (4/87) precluded an exposure-response assessment on outcomes. A comparable rate (13% vs 11%) of atezolizumab anti-drug antibodies was seen in pediatric and young adult patients.

CONCLUSIONS

These findings demonstrate a similar exposure-safety profile of atezolizumab in pediatric and young adult patients, supportive of weight-based dosing in pediatric patients.

TRIAL REGISTRATION

NCT02541604.