Pharmacokinetics and population pharmacokinetics in pediatric oncology

Therapeutic drug monitoring guidelines in oncology: what do we know and how to move forward? Insights from a systematic review

Background

Compared with anti-infective drugs, immunosuppressants and other fields, the application of therapeutic drug monitoring (TDM) in oncology is somewhat limited.

Objective

We aimed to provide a comprehensive understanding of TDM guidelines for antineoplastic drugs and to promote the development of individualized drug therapy in oncology.

Design

This study type is a systematic review.

Data sources and methods

This study was performed and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement. Databases including PubMed, Embase, the official websites of TDM-related associations and Chinese databases were comprehensively searched up to March 2023. Two investigators independently screened the literature and extracted data. The methodological and reporting quality was evaluated using the Appraisal of Guidelines for Research and Evaluation II (AGREE II) and the Reporting Items for Practice Guidelines in Healthcare (RIGHT), respectively. Recommendations and quality evaluation results were presented by visual plots. This study was registered in PROSPERO (No. CRD42022325661).

Results

A total of eight studies were included, with publication years ranging from 2014 to 2022. From the perspective of guideline development, two guidelines were developed using evidence-based methods. Among the included guidelines, four guidelines were for cytotoxic antineoplastic drugs, three for small molecule kinase inhibitors, and one for antineoplastic biosimilars. Currently available guidelines and clinical practice provided recommendations of individualized medication in oncology based on TDM, as well as influencing factors. With regard to methodological quality based on AGREE II, the average overall quality score was 55.21%. As for the reporting quality by RIGHT evaluation, the average reporting rate was 53.57%.

Conclusion

From the perspective of current guidelines, TDM in oncology is now being expanded from cytotoxic antineoplastic drugs to newer targeted treatments. Whereas, the types of antineoplastic drugs involved are still small, and there is still room for quality improvement. Furthermore, the reflected gaps warrant future studies into the exposure-response relationships and population pharmacokinetics models.

Knowledge, attitudes and practices of Egyptian healthcare professionals toward therapeutic drug monitoring service as a principal component of personalized medicine

Aim: To assess pharmacists' and physicians' knowledge, attitudes and practices toward therapeutic drug monitoring (TDM) service at the Children's Cancer Hospital Egypt 57357. Materials & methods: This was a single-site cross-sectional study where all practicing pharmacists and physicians were eligible to participate. Results: A statistically significant difference in the knowledge scores between pharmacists and physicians (p = 0.022) was found. In general, attitudes toward TDM among pharmacists and physicians were positive. Regarding practices, pharmacists were more likely than physicians to agree or strongly agree that they have studied some scientific references on TDM (p = 0.034), but more physicians recommend the TDM service (p = 0.046). Conclusion: A multidisciplinary educational program in Egypt for TDM for both medicine and pharmacy staff will improve interprofessional collaboration in the clinical setting, leading to better personalized medication management.

Colony stimulating factors for prophylaxis of chemotherapy-induced neutropenia in children

INTRODUCTION

Febrile neutropenia (FN) is one of the complications of chemotherapy that can increase the risk of infection and mortality. Granulocyte colony-stimulating factors (G-CSFs) are used in practice to prevent and treat episodes of neutropenia. The use of G-CSFs in children with cancer has not been studied much for primary prophylaxis of FN.

AREAS COVERED

Current data suggest that G-CSFs have a similar pharmacokinetic profile in children and adults. Clinical trials published from 2002 to 2021 using G-CSFs in pediatric cancer patients were reviewed. All evaluated clinical trials used a dosage of 5 mcg/kg of filgrastim daily until neutrophil recovery or a single dose of 100 mcg/kg pegfilgrastim. Filgrastim demonstrated the benefit in decreasing the duration of fever, hospital stay, and antibiotic use in high-risk neuroblastoma patients. Pegfilgrastim showed similar efficacy in reducing the occurrence of FN and infections, with bone pain as an adverse effect.

EXPERT OPINION

Filgrastim 5 mcg/kg/day or pegfilgrastim 100 mcg/kg single dose is appropriate when given at least 24 hours or after the chemotherapy in pediatric patients who weigh 45 kg or more. More prospective randomized trials are necessary to further investigate the efficacy and safety of G-CSFs in children with different types of cancer.

Clinical pharmacology of cytotoxic drugs in neonates and infants: Providing evidence-based dosing guidance

Cancer in neonates and infants is a rare but challenging entity. Treatment is complicated by marked physiological changes during the first year of life, excess rates of toxicity, mortality, and late effects. Dose optimisation of chemotherapeutics may be an important step to improving outcomes. Body size–based dosing is used for most anticancer drugs used in infants. However, dose regimens are generally not evidence based, and dosing strategies are frequently inconsistent between tumour types and treatment protocols. In this review, we collate available pharmacological evidence supporting dosing regimens in infants for a wide range of cytotoxic drugs. A systematic review was conducted, and available data ranked by a level of evidence (1–5) and a grade of recommendation (A–D) provided on a consensus basis, with recommended dosing approaches indicated as appropriate. For 9 of 29 drugs (busulfan, carboplatin, cyclophosphamide, daunorubicin, etoposide, fludarabine, isotretinoin, melphalan and vincristine), grade A was scored, indicating sufficient pharmacological evidence to recommend a dosing algorithm for infants. For busulfan and carboplatin, sufficient data were available to recommend therapeutic drug monitoring in infants. For eight drugs (actinomycin D, blinatumomab, dinutuximab, doxorubicin, mercaptopurine, pegaspargase, thioguanine and topotecan), some pharmacological evidence was available to guide dosing (graded as B). For the remaining drugs, including commonly used agents such as cisplatin, cytarabine, ifosfamide, and methotrexate, pharmacological evidence for dosing in infants was limited or non-existent: grades C and D were scored for 10 and 2 drugs, respectively. The review provides clinically relevant evidence-based dosing guidance for cytotoxic drugs in neonates and infants.

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Treating cancer in neonates and infants is challenging.

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Dose optimisation of cytotoxic drugs is an important step to improving outcomes.

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Clinical pharmacological evidence supporting dosing regimens in infants was collated.

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All available pharmacological evidence was ranked by a level of evidence.

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A grade of recommendation was derived and a recommended dose per agent provided.

Effect of Genetic Variation in CYP450 on Gonadal Impairment in a European Cohort of Female Childhood Cancer Survivors, Based on a Candidate Gene Approach: Results from the PanCareLIFE Study

BACKGROUND

Female childhood cancer survivors (CCSs) carry a risk of therapy-related gonadal dysfunction. Alkylating agents (AA) are well-established risk factors, yet inter-individual variability in ovarian function is observed. Polymorphisms in CYP450 enzymes may explain this variability in AA-induced ovarian damage. We aimed to evaluate associations between previously identified genetic polymorphisms in CYP450 enzymes and AA-related ovarian function among adult CCSs.

METHODS

Anti-Müllerian hormone (AMH) levels served as a proxy for ovarian function in a discovery cohort of adult female CCSs, from the pan-European PanCareLIFE cohort (n = 743; age (years): median 25.8, interquartile range (IQR) 22.1-30.6). Using two additive genetic models in linear and logistic regression, nine genetic variants in three CYP450 enzymes were analyzed in relation to cyclophosphamide equivalent dose (CED) score and their impact on AMH levels. The main model evaluated the effect of the variant on AMH and the interaction model evaluated the modifying effect of the variant on the impact of CED score on log-transformed AMH levels. Results were validated, and meta-analysis performed, using the USA-based St. Jude Lifetime Cohort (n = 391; age (years): median 31.3, IQR 26.6-37.4).

RESULTS

CYP3A4*3 was significantly associated with AMH levels in the discovery and replication cohort. Meta-analysis revealed a significant main deleterious effect (Beta (95% CI): -0.706 (-1.11--0.298), p-value = 7 × 10-4) of CYP3A4*3 (rs4986910) on log-transformed AMH levels. CYP2B6*2 (rs8192709) showed a significant protective interaction effect (Beta (95% CI): 0.527 (0.126-0.928), p-value = 0.01) on log-transformed AMH levels in CCSs receiving more than 8000 mg/m2 CED.

CONCLUSIONS

Female CCSs CYP3A4*3 carriers had significantly lower AMH levels, and CYP2B6*2 may have a protective effect on AMH levels. Identification of risk-contributing variants may improve individualized counselling regarding the treatment-related risk of infertility and fertility preservation options.

Model-Informed Precision Dosing of Antibiotics in Pediatric Patients: A Narrative Review

Optimal pharmacotherapy in pediatric patients with suspected infections requires understanding and integration of relevant data on the antibiotic, bacterial pathogen, and patient characteristics. Because of age-related physiological maturation and non-maturational covariates (e.g., disease state, inflammation, organ failure, co-morbidity, co-medication and extracorporeal systems), antibiotic pharmacokinetics is highly variable in pediatric patients and difficult to predict without using population pharmacokinetics models. The intra- and inter-individual variability can result in under- or overexposure in a significant proportion of patients. Therapeutic drug monitoring typically covers assessment of pharmacokinetics and pharmacodynamics, and concurrent dose adaptation after initial standard dosing and drug concentration analysis. Model-informed precision dosing (MIPD) captures drug, disease, and patient characteristics in modeling approaches and can be used to perform Bayesian forecasting and dose optimization. Incorporating MIPD in the electronic patient record system brings pharmacometrics to the bedside of the patient, with the aim of a consisted and optimal drug exposure. In this narrative review, we evaluated studies assessing optimization of antibiotic pharmacotherapy using MIPD in pediatric populations. Four eligible studies involving amikacin and vancomycin were identified from 418 records. Key articles, independent of year of publication, were also selected to highlight important attributes of MIPD. Although very little research has been conducted until this moment, the available data on vancomycin indicate that MIPD is superior compared to conventional dosing strategies with respect to target attainment. The utility of MIPD in pediatrics needs to be further confirmed in frequently used antibiotic classes, particularly aminoglycosides and beta-lactams.