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Medication use in children represents 15-20% of total drug sales. More than 50% of children receive at least one prescription medication a year. Despite this, few drugs have a paediatric formulation available. Furthermore, 80% of paediatric prescriptions are considered off-label. Off-label use is defined as the use of products that differ in dose, indication or route of administration from the one established in the summary of product characteristics. Off-label use is associated with an increased risk of adverse drug reactions, including therapeutic failure. The US Food and Drug Administration and the European Medicines Agency have made changes to regulations to incentivize the development of paediatric formulations. Novel paediatric formulations can ease drug administration, reducing medication errors, increasing dosing acceptability, medication adherence and improve safety. Two routes for paediatric drug approval are available, the traditional, requiring clinical trials and the formulation bridging path, where these formulations need to demonstrate equivalence with the existing adult formulations. New formulations seeking regulatory approval require bioequivalence studies, but the regulatory framework, which states that bioequivalence data are obtained from adults and then extrapolated to children, may be disregarding important physiological differences between these two populations of patients. It is important to ensure that drugs for children have been appropriately studied and are properly manufactured for them. Adequately designed studies will provide data that will improve our understanding of how drug disposition differs between adults and children and will pave the way for children to get the best possible treatment., (© 2022 British Pharmacological Society.)

Cancer is the leading cause of death in American children older than 1 year of age. Major developments in drugs such as thiopurines and optimization in clinical trial protocols for treating cancer in children have led to a remarkable improvement in survival, from approximately 30% in the 1960s to more than 80% today. Short-term and long-term adverse effects of chemotherapy still affect most survivors of childhood cancer. Pharmacogenetics plays a major role in predicting the safety of cancer chemotherapy and, in the future, its effectiveness. Treatment failure in childhood cancer-due to either serious adverse effects that limit therapy or the failure of conventional dosing to induce remission-warrants development of new strategies for treatment. Here, we summarize the current knowledge of the pharmacogenomics of cancer drug treatment in children and of statistically and clinically relevant drug-gene associations and the mechanistic understandings that underscore their therapeutic value in the treatment of childhood cancer.

Purpose of Review: Adverse drug reactions (ADRs) are a serious burden and can negatively impact patient quality of life. One of these ADRs, anthracycline-induced cardiotoxicity (ACT), occurs in up to 65% of treated patients and can lead to congestive heart failure. Pharmacogenetic studies have helped to reveal the mechanisms of ACT and, consequently, inform current strategies to prevent ACT in the clinic., Recent Findings: Many pharmacogenetic studies have been conducted for ACT, but few have led to the development of clinical practice guidelines and clinical genetic testing for ACT. This is, in part, because of lack of replication in independent patient cohorts and/or validation of an affected biological pathway. Recent advances in pharmacogenetic studies have been made through the use of novel methods that directly implicate dysregulated genes and perturbed biological pathways in response to anthracycline treatment., Summary: Furthering the understanding of the genetics and altered biological pathways of ACT through these novel methods can inform clinical treatment strategies and enable refinement of current clinical practice guidelines. This can therefore lead to improvement in clinical pharmacogenetic testing for further reduction of the incidence of ACT in pediatric cancer patients taking anthracyclines.

Motivation: Adverse drug reactions are one of the major factors that affect the wellbeing of patients and financial costs of healthcare systems. Genetic variations of patients have been shown to be a key factor in the occurrence and severity of many ADRs. However, the large number of confounding drugs and genetic biomarkers for each adverse reaction case demands a method that evaluates all potential genetic causes of ADRs simultaneously., Results: To address this challenge, we propose HUME, a multi-phase algorithm that recommends genetic factors for ADRs that are causally supported by the patient record data. HUME consists of the construction of a network from co-prevalence between significant genetic biomarkers and ADRs, a link score phase for predicting candidate relations based on the Adamic-Adar measure, and a causal refinement phase based on multiple hypothesis testing of quasi experimental designs for evaluating evidence and counter evidence of candidate relations in the patient records., Supplementary Information: Supplementary data are available at Bioinformatics online.

The variant allele HLA-B*15:02 is strongly associated with greater risk of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) in patients treated with carbamazepine or oxcarbazepine. The variant allele HLA-A*31:01 is associated with greater risk of maculopapular exanthema, drug reaction with eosinophilia and systemic symptoms, and SJS/TEN in patients treated with carbamazepine. We summarize evidence from the published literature supporting these associations and provide recommendations for carbamazepine and oxcarbazepine use based on HLA genotypes., (© 2018 American Society for Clinical Pharmacology and Therapeutics.)

Background: Recently, the US Food and Drug Administration issued a warning regarding the potential risk of gambling disorder, but large epidemiologic studies are lacking., Methods: We used a large health claims database from the United States and conducted a nested case-control study. Cases were defined as subjects newly diagnosed with gambling disorder or impulse control disorder. For each case, 10 controls were selected and matched to cases by age and follow-up time and calendar time. Adjusted rate ratios were computed with conditional logistic regression., Results: There are 355 cases of gambling disorder and 3550 controls along with 4341 cases of impulse control disorder and 43,410 corresponding controls. After adjusting for confounders, users of aripiprazole demonstrated an increased risk of pathologic gambling (rate ratio [RR], 5.23; 95% confidence interval [CI], 1.78-15.38) and impulse control disorder (RR, 7.71; 95% CI, 5.81-10.34). The risk was also elevated for pramipexole or ropinirole for both gambling disorder and impulse control disorder (RR, 7.61; 95% CI, 2.75-21.07; RR, 3.28; 95% CI, 2.31-4.66, respectively)., Conclusions: Our study confirms an association between aripiprazole, pramipexole, or ropinirole and impulse control disorder and gambling disorder.

Differences in the frequency of pharmacogenomic variants may influence inter-population variability in drug efficacy and risk of adverse drug reactions (ADRs). We investigated the diversity of ∼ 4500 genetic variants in key drug-biotransformation and -response genes among three South East Asian populations compared with individuals of European ancestry. We compared rates of reported ADRs in these Asian populations to determine if the allelic differentiation corresponded to an excess of the associated ADR. We identified an excess of ADRs related to clopidogrel in Singaporean Chinese, consistent with a higher frequency of a known risk variant in CYP2C19 in that population. We also observed an excess of ADRs related to platinum compounds in Singaporean CHS, despite a very low frequency of known ADR risk variants, suggesting the presence of additional genetic and non-genetic risk factors. Our results point to substantial diversity at specific pharmacogenomic loci that may contribute to inter-population variability in drug response phenotypes.

There is established clinical evidence for differences in drug response, cure rates and survival outcomes between different ethnic populations, but the causes are poorly understood. Differences in frequencies of functional genetic variants in key drug response and metabolism genes may significantly influence drug response differences in different populations. To assess this, we genotyped 1330 individuals of African (n=372) and European (n=958) descent for 4535 single-nucleotide polymorphisms in 350 key drug absorption, distribution, metabolism, elimination and toxicity genes. Important and remarkable differences in the distribution of genetic variants were observed between Africans and Europeans and among the African populations. These could translate into significant differences in drug efficacy and safety profiles, and also in the required dose to achieve the desired therapeutic effect in different populations. Our data points to the need for population-specific genetic variation in personalizing medicine and care.

Background: The impact of genetic factors on the risk of adverse drug reactions (ADRs) is being increasingly recognized as clinically important. ADR Prioritization Tool (APT) was developed to facilitate the prioritization of drugs and their associated ADRs for future pharmacogenomic studies., Objectives: To describe a novel tool developed for the prioritization of pharmacogenomic investigation of ADRs and discuss the impact of specific scoring criteria., Methods: APT scores were based on 25 key scientific and feasibility criteria relevant for clinical research evaluating the genetic basis of ADRs, with a maximum possible score of 60 points. The tool was independently applied to five ADRs (warfarin-induced bleeding/thrombosis, cisplatin-induced ototoxicity, methotrexate-induced neutropenia, carbamazepine-induced Stevens-Johnson syndrome, and abacavir-induced hypersensitivity) by two researchers. Scores were compared using the intraclass correlation coefficient (ICC) to determine level of agreement., Results: Overall scores for target ADRs ranged from 19.5 to 44 points (33-73% of maximum possible score). Cisplatin-induced ototoxicity, a frequent and severe ADR, received the highest score (44). Lower scores were obtained for abacavir-induced hypersensitivity (19.5) and methotrexate-induced neutropenia (28). High agreement was observed between the scientific, feasibility, and total scores from two reviewers (ICC values = 0.895, 0.980, and 0.983, respectively)., Conclusion: Application of APT enables simple and direct comparison of potential study targets for research groups embarking on pharmacogenomic investigation of ADRs. Research teams will be able to identify which study targets are best suited for their research environment and discern how to optimize resource allocation for successful discovery and replication of clinically relevant biomarkers.

There is an urgency to improve the evaluation of pediatric drug safety in the pre-market and post-market phases of drug evaluation. The need to improve pharmacovigilance methods concerns not only new drugs but also existing drugs that have been used for many years in an off-label manner in children. Effective methods for early detection of adverse drug reactions (ADRs) and drug safety epidemiologic studies are a pressing need in pediatrics. Moreover, the nature and severity of an ADR as well as the extent to which the suspected drug is being used, will determine how quickly the information about risk needs to be made available to users and what would be the most appropriate method of communication. Based on our experience through the Genotype-specific Approaches to Therapy in Children study, an active ADR surveillance network of pediatric hospitals across Canada, we present five strategic elements that should be included in pharmacovigilance initiatives in pediatrics: active ADR surveillance; drug or ADR targeted pharmacovigilance; trained surveillance clinicians; case-control methodology and standardized procedures for recognition; reporting and evaluating drug-induced harm. In addition, linking pharmacovigilance with pharmacogenomics to find drug safety solutions is presented as a promising strategy for knowledge generation. Finally, we discuss the importance of an efficient translation of the pharmacovigilance knowledge into clinical practice to achieve safer drug therapy in children.

Juxtaposing clinical pharmacology with human genetics, pharmacogenomics utilizes a patient's genetic information to identify genetic variants that have the potential to provide clinically relevant predictions of toxicity and efficacy. The goal is to develop personalized and genetic-based predictions of an individual's drug response and likelihood of experiencing an adverse drug reaction. The Canadian Pharmacogenomics Network for Drug Safety (CPNDS) has implemented active adverse drug reaction surveillance to monitor and discover genetic markers related to serious adverse drug reactions in the pediatric population. Evidence-based pharmacogenomics research will inform public policy and influence drug benefit-risk decision-making. Regulatory processes and future challenges in pharmacogenomics research will be discussed.

Background: Adverse drug reactions (ADRs) rank as one of the top 10 leading causes of death in the developed world, and the direct medical costs of ADRs exceed $100 billion annually in the United States alone. Pharmacogenomics research seeks to identify genetic factors that are responsible for individual differences in drug efficacy and susceptibility to ADRs. This has led to several genetic tests that are currently being used to provide clinical recommendations. The Canadian Pharmacogenomics Network for Drug Safety is a nation-wide effort established in Canada to identify novel predictive genomic markers of severe ADRs in children and adults. A surveillance network has been established in 17 of Canada's major hospitals to identify patients experiencing specific ADRs and to collect biological samples and relevant clinical history for genetic association studies. To identify ADR-associated genetic markers that could be incorporated into predictive tests that will reduce the occurrence of serious ADRs, high-throughput genomic analyses are conducted with samples from patients that have suffered serious ADRs and matched control patients., Summary: ADRs represent a significant unmet medical problem with significant morbidity and mortality, and Canadian Pharmacogenomics Network for Drug Safety is a nation-wide network in Canada that seeks to identify genetic factors responsible for interindividual differences in susceptibility to serious ADRs., Conclusions: Active ADR surveillance is necessary to identify and recruit patients who suffer from serious ADRs. National and international collaborations are required to recruit sufficient patients for these studies. Several pharmacogenomics tests are currently in clinical use to provide dosing recommendations, and the number of pharmacogenomics tests is expected to significantly increase in the future.

Adverse drug reactions (ADRs) are a major cause of morbidity and mortality in children. Current models of ADR surveillance have repeatedly demonstrated little pragmatic value to practicing clinicians. ADR reporting rates in the US and Canada suggest that only 5% of ADRs are reported. The Genotypic Approaches to Therapy in Children (GATC) network was established to identify and solve drug safety problems in paediatrics. We hypothesized that genetic polymorphisms underlie a significant portion of concentration-dependent ADRs in children. Our objective was to establish an ADR active surveillance network in paediatric hospitals across Canada. Surveillance clinicians evaluate clinical information from ADR cases and drug-matched controls, and collected DNA samples from all patients. The surveillance network will enable the identification of predictive genomic-markers for ADRs. With this knowledge, children at risk can be identified before therapy is initiated and enable personalized adjustments to therapy based on genetic make-up.

Background: Severe adverse drug reactions (ADRs) are an important cause of childhood morbidity and mortality. 95% of ADRs are likely not reported, less than 25% of marketed drugs can be advertised as safe and effective in children; yet over 50% of Canadian children receive prescription drugs annually., Objectives: To increase understanding of reported ADRs in Canadian children., Methods: A retrospective analysis of 1193 suspected ADRs reported to Health Canada (January 1998 - May 2002). These data were a paediatric subset of the Canadian Adverse Drug Reaction Information System database., Results: 58.6% of ADRs were for children over 13 years. 61% of reports were defined by Health Canada as serious. Case outcomes include: death (n=41) and recovered with sequelae (n=14). 4 reports of interacting drugs had fatal outcomes. Drugs most frequently cited include: isotretinoin (n=56), paroxetine (n=42), methylphenidate (n=41), amoxicillin (n=40), and valproic acid (n=32). Most frequent reaction descriptors include: psychiatric disorders (isotretinoin and paroxetine) and nervous system disorders (valproic acid, bupropion and carbamazepine). Causal links between suspected ADRs and clinical outcomes have not been established., Conclusions: Current ADR reporting is insufficient to improve patient safety. More detailed reporting, including case outcomes, is needed. Mandatory ADR reporting is unlikely to improve underreporting. Trained surveillance personnel located in major health centres and solely dedicated to ADR reporting may provide a more accurate determination of ADRs in Canadian children.