Carboplatin therapeutic monitoring in preterm and full-term neonates

Utility of carboplatin therapeutic drug monitoring for the treatment of neonate and infant retinoblastoma patients in the United Kingdom

BACKGROUND

Retinoblastoma is the most common intra-ocular malignancy in children and frequently presents in very young patients who commonly require intravenous carboplatin. Delivering this is challenging due to a lack of uniform dosing recommendations, rapid changes in physiological function and the risk of side-effects.

METHODS

We conducted a retrospective review of neonates and infants in the UK with retinoblastoma, who have undergone carboplatin therapeutic drug monitoring (TDM). We report on the pharmacokinetic, treatment efficacy and toxicity data.

RESULTS

In total, 29 patients (median age 5 weeks at treatment onset) underwent a total of 74 TDM guided cycles of chemotherapy, involving real time sampling and dose adjustment. An additional 13 patients underwent TDM sampling to modify doses between cycles. Without the adoption of TDM guided dosing, carboplatin exposures would have been ≥20% outside the target AUC in 38/78 (49%) of treatment cycles. Excellent responses and a reassuringly low incidence of toxicities were observed following dose adjustment, despite the young patient age and the implementation of dose increases in the majority of cases.

CONCLUSIONS

Real time TDM is safe, effective and deliverable for neonates and infants receiving carboplatin for retinoblastoma and should be considered standard of care up to the age of 6 months.

Electrochemical Sensing Device for Carboplatin Monitoring in Proof-of-Concept Drug Delivery Nanosystems

(1) Background: Carboplatin (CBP) is a chemotherapeutic drug widely used in the treatment of a variety of cancers. Despite its efficiency, CBP is associated with side effects that greatly limit its clinical use. To mitigate these effects, CBP can be encapsulated in targeted delivery systems, such as liposomes. Ensuring the adequate loading and release of CBP from these carriers requires strict control in pharmaceutical formulation development, demanding modern, rapid, and robust analytical methods. The aim of this study was the development of a sensor for the fast and accurate quantification of CBP and its application on proof-of-concept CBP-loaded nanosomes. (2) Methods: Screen-printed electrodes were obtained in-lab and the electrochemical behavior of CBP was tested on the obtained electrodes. (3) Results: The in-lab screen-printed electrodes demonstrated superior properties compared to commercial ones. The novel sensors demonstrated accurate detection of CBP on a dynamic range from 5 to 500 μg/mL (13.5-1350 μM). The method was successfully applied on CBP loaded and released from nanosomes, with strong correlations with a spectrophotometric method used as control. (4) Conclusions: This study demonstrates the viability of electrochemical techniques as alternative options during the initial phases of pharmaceutical formulation development.

Model-Informed Precision Dosing to Reduce Vincristine-Induced Peripheral Neuropathy in Pediatric Patients: A Pharmacokinetic and Pharmacodynamic Modeling and Simulation Analysis

BACKGROUND

Vincristine-induced peripheral neuropathy (VIPN) is a common adverse effect of vincristine, a drug often used in pediatric oncology. Previous studies demonstrated large inter- and intrapatient variability in vincristine pharmacokinetics (PK). Model-informed precision dosing (MIPD) can be applied to calculate patient exposure and individualize dosing using therapeutic drug monitoring (TDM) measurements. This study set out to investigate the PK/pharmacodynamic (PKPD) relationship of VIPN and determine the utility of MIPD to support clinical decisions regarding dose selection and individualization.

METHODS

Data from 35 pediatric patients were utilized to quantify the relationship between vincristine dose, exposure and the development of VIPN. Measurements of vincristine exposure and VIPN (Common Terminology Criteria for Adverse Events [CTCAE]) were available at baseline and for each subsequent dosing occasions (1-5). A PK and PKPD analysis was performed to assess the inter- and intraindividual variability in vincristine exposure and VIPN over time. In silico trials were performed to portray the utility of vincristine MIPD in pediatric subpopulations with a certain age, weight and cytochrome P450 (CYP) 3A5 genotype distribution.

RESULTS

A two-compartmental model with linear PK provided a good description of the vincristine exposure data. Clearance and distribution parameters were related to bodyweight through allometric scaling. A proportional odds model with Markovian elements described the incidence of Grades 0, 1 and ≥ 2 VIPN overdosing occasions. Vincristine area under the curve (AUC) was the most significant exposure metric related to the development of VIPN, where an AUC of 50 ng⋅h/mL was estimated to be related to an average VIPN probability of 40% over five dosing occasions. The incidence of Grade ≥ 2 VIPN reduced from 62.1 to 53.9% for MIPD-based dosing compared with body surface area (BSA)-based dosing in patients. Dose decreases occurred in 81.4% of patients with MIPD (vs. 86.4% for standard dosing) and dose increments were performed in 33.4% of patients (no dose increments allowed for standard dosing).

CONCLUSIONS

The PK and PKPD analysis supports the use of MIPD to guide clinical dose decisions and reduce the incidence of VIPN. The current work can be used to support decisions with respect to dose selection and dose individualization in children receiving vincristine.

Generation of evidence-based carboplatin dosing guidelines for neonates and infants

BACKGROUND

To optimally dose childhood cancer patients it is essential that we apply evidence-based dosing approaches. Carboplatin is commonly dosed to achieve a cumulative target exposure (AUC) in children, with target AUC values of 5.2-7.8 mg/ml.min defined. To achieve these exposures patients are dosed at 6.6 mg/kg/day or 4.4 mg/kg for patients <5 kg. The current study uses real world clinical pharmacology data to optimise body weight-based doses to effectively target AUCs of 5.2-7.8 mg/ml.min in infants.

METHODS

Carboplatin exposures were determined across 165 treatment cycles in 82 patients ≤10 kg. AUC and clearance values were determined by Bayesian modelling from samples collected on day 1. These parameters were utilised to assess current dosing variability, determine doses required to achieve target AUC values and predict change in AUC using the modified dose.

RESULTS

No significant differences in clearance were identified between patients <5 kg and 5-10 kg. Consequently, for patients <5 kg, 4.4 mg/kg dosing was not sufficient to achieve a target AUC of 5.2 mg/ml.min, with <55% of patients within 25% of this target. Optimised daily doses for patients ≤10 kg were 6 mg/kg and 9 mg/kg for cumulative carboplatin target exposures of 5.2 and 7.8 mg/ml.min, respectively.

CONCLUSIONS

Adoption of these evidence-based carboplatin doses in neonates and infants will reduce drug exposure variability and positively impact treatment.

Clinical utility of vinblastine therapeutic drug monitoring for the treatment of infantile myofibroma patients: A case series

Infantile myofibroma is a rare, benign tumour of infancy typically managed surgically. In a minority of cases, more aggressive disease is seen and chemotherapy with vinblastine and methotrexate may be used, although evidence for this is limited. Chemotherapy dosing in infants is challenging, and vinblastine disposition in infants is unknown. We describe the use of vinblastine therapeutic drug monitoring in four cases of infantile myofibroma. Marked inter- and intrapatient variability was observed, highlighting the poorly understood pharmacokinetics of vinblastine in children, the challenges inherent in treating neonates, and the role of adaptive dosing in optimising drug exposure in challenging situations.

Optimized Dosing: The Next Step in Precision Medicine in Non-Small-Cell Lung Cancer

In oncology, and especially in the treatment of non-small-cell lung cancer (NSCLC), dose optimization is often a neglected part of precision medicine. Many drugs are still being administered in "one dose fits all" regimens or based on parameters that are often only minor determinants for systemic exposure. These dosing approaches often introduce additional pharmacokinetic variability and do not add to treatment outcomes. Fortunately, pharmacological knowledge is increasing, providing valuable information regarding the potential of, for example, therapeutic drug monitoring. This article focuses on the evidence for the most promising and easily implemented optimized dosing approaches for the small-molecule inhibitors, chemotherapeutic agents, and monoclonal antibodies as treatment options currently approved for NSCLC. Despite limitations such as investigations having been conducted in oncological diseases other than NSCLC or the retrospective origin of many analyses, an alternative dosing regimen could be beneficial for treatment outcomes, prescriber convenience, or financial burden on healthcare systems. This review of the literature provides recommendations on the implementation of dose optimization and advice regarding promising strategies that deserve further research in NSCLC.

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.

Carboplatin Dosing in Children Using Estimated Glomerular Filtration Rate: Equation Matters

Renal function-based carboplatin dosing using measured glomerular filtration rate (GFR) results in more consistent drug exposure than anthropometric dosing. We aimed to validate the Newell dosing equation using estimated GFR (eGFR) and study which equation most accurately predicts carboplatin clearance in children with retinoblastoma. In 13 children with retinoblastoma 38 carboplatin clearance values were obtained from individual fits using MWPharm++. Carboplatin exposure (AUC) was calculated from administered dose and observed carboplatin clearance and compared to predicted AUC calculated with a carboplatin dosing equation (Newell) using different GFR estimates. Different dosing regimens were compared in terms of accuracy, bias and precision. All patients had normal eGFR. Carboplatin exposure using cystatin C-based eGFR equations tended to be more accurate compared to creatinine-based eGFR (30% accuracy 76.3-89.5% versus 76.3-78.9%, respectively), which led to significant overexposure, especially in younger (aged ≤ 2 years) children. Of all equations, the Schwartz cystatin C-based equation had the highest accuracy and lowest bias. Although anthropometric dosing performed comparably to many of the eGFR equations overall, we observed a weight-dependent change in bias leading to underdosing in the smallest patients. Using cystatin C-based eGFR equations for carboplatin dosing in children leads to more accurate carboplatin-exposure in patients with normal renal function compared to anthropometric dosing. In children with impaired kidney function, this trend might be more pronounced. Anthropometric dosing is hampered by a weight-dependent bias.

Vincristine dosing, drug exposure and therapeutic drug monitoring in neonate and infant cancer patients

Background

The anticancer drug vincristine is associated with potentially dose-limiting side-effects, including neurotoxicity and myelosuppression. However, there currently exists a lack of published clinical pharmacology data relating to its use in neonate and infant patients. We report a study investigating vincristine dosing and drug exposure, alongside the feasibility and impact of a therapeutic drug monitoring treatment approach, in this challenging patient population.

Patients and methods

Vincristine pharmacokinetic data from a total of 57 childhood cancer patients, including 26 neonates and infants, were used to characterise a population pharmacokinetic model. Vincristine was administered at doses of 0.02–0.05 mg/kg or 0.75–1.5 mg/m² in neonates and infants aged <1 year or ≤12 kg and doses of 1.5 mg/m² in older children.

Results

A two-compartment model provided the best fit for the population analysis. There was no significant difference in vincristine clearance normalised for body surface area between neonates/infants and older children. Lower doses administered to neonates and infants resulted in significantly lower drug exposures (area under the curve [AUC]), compared with older children (p = 0.047). Vincristine doses of <0.05 mg/kg in neonates and infants resulted in significantly lower AUC values than observed in those receiving doses of ≥0.05 mg/kg (p ≤ 0.0001). Therapeutic drug monitoring was shown to be feasible, effective and well tolerated in neonates and infants experiencing suboptimal drug exposures.

Conclusion

Doses of <0.05 mg/kg should not be used in neonate and infant patients because of a high risk of patients experiencing potentially suboptimal drug exposures. Therapeutic drug monitoring approaches in neonates and infants are supported by the data generated, with a proposed target therapeutic window of 50–100 μg/l∗h.

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Vincristine dosing and drug exposure was investigated in neonates and infants.

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Vincristine concentrations were quantified in 210 plasma samples from 57 children.

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Lower drug exposures were observed in infants and neonates compared with older children.

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Therapeutic drug monitoring can be used to avoid suboptimal vincristine drug exposures.

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Vincristine dosing guidance is provided for treatment of neonate and infant patients.

Pregnancy and viral infections: Mechanisms of fetal damage, diagnosis and prevention of neonatal adverse outcomes from cytomegalovirus to SARS-CoV-2 and Zika virus

Some maternal infections, contracted before or during pregnancy, can be transmitted to the fetus, during gestation (congenital infection), during labor and childbirth (perinatal infection) and through breastfeeding (postnatal infection). The agents responsible for these infections can be viruses, bacteria, protozoa, fungi. Among the viruses most frequently responsible for congenital infections are Cytomegalovirus (CMV), Herpes simplex 1–2, Herpes virus 6, Varicella zoster. Moreover Hepatitis B and C virus, HIV, Parvovirus B19 and non-polio Enteroviruses when contracted during pregnancy may involve the fetus or newborn at birth. Recently, new viruses have emerged, SARS-Cov-2 and Zika virus, of which we do not yet fully know the characteristics and pathogenic power when contracted during pregnancy.

Viral infections in pregnancy can damage the fetus (spontaneous abortion, fetal death, intrauterine growth retardation) or the newborn (congenital anomalies, organ diseases with sequelae of different severity). Some risk factors specifically influence the incidence of transmission to the fetus: the timing of the infection in pregnancy, the order of the infection, primary or reinfection or chronic, the duration of membrane rupture, type of delivery, socio-economic conditions and breastfeeding. Frequently infected neonates, symptomatic at birth, have worse outcomes than asymptomatic. Many asymptomatic babies develop long term neurosensory outcomes.

The way in which the virus interacts with the maternal immune system, the maternal-fetal interface and the placenta explain these results and also the differences that are observed from time to time in the fetal‑neonatal outcomes of maternal infections. The maternal immune system undergoes functional adaptation during pregnancy, once thought as physiological immunosuppression. This adaptation, crucial for generating a balance between maternal immunity and fetus, is necessary to promote and support the pregnancy itself and the growth of the fetus. When this adaptation is upset by the viral infection, the balance is broken, and the infection can spread and lead to the adverse outcomes previously described. In this review we will describe the main viral harmful infections in pregnancy and the potential mechanisms of the damages on the fetus and newborn.

Pharmacokinetics and Pharmacogenetics of Cyclophosphamide in a Neonate and Infant Childhood Cancer Patient Population

Infants and young children represent an important but much understudied childhood cancer patient population. The pharmacokinetics and pharmacogenetics of the widely used anticancer prodrug cyclophosphamide were investigated in children <2 years of age. Concentrations of cyclophosphamide and selected metabolites were determined in patients administered cyclophosphamide at doses ranging from 100–1500 mg/m² (5–75 mg/kg), with various infusion times as determined by the standard treatment regimen that each patient was receiving. Polymorphisms in genes including CYP2B6 and CYP2C19 were investigated. Data generated for cyclophosphamide were analysed using a previously published population pharmacokinetic model. Cyclophosphamide pharmacokinetics was assessed in 111 samples obtained from 25 patients ranging from 4–23 months of age. The average cyclophosphamide clearance for the patients was 46.6 mL/min/m² (ranging from 9.4–153 mL/min/m²), with marked inter-patient variability observed (CV 41%). No significant differences in cyclophosphamide clearance or exposure (AUC) were observed between patient groups as separated by age or body weight. However, marked differences in drug clearance and metabolism were noted between the current data in children <2 years of age and recently published results from a comparable study conducted by our group in older children, which reported significantly lower cyclophosphamide clearance values and metabolite exposures using the same population pharmacokinetic model for analysis. Whilst this study demonstrates no significant differences in cyclophosphamide clearance in patients <2 years, it highlights large differences in dosing protocols across tumour types. Furthermore, the study suggests marked differences in cyclophosphamide clearance in children less than two years of age as compared to older patients.

Diversity of dose-individualization and therapeutic drug monitoring practices of platinum compounds: a review

Introduction: Platinum-derived drugs are commonly used for the treatment of solid tumors. The differences in chemical structures of these molecules lead to different pharmacological properties, in terms of indication, efficacy, and toxicity. Their pharmacokinetics (PK) differ according to their respective renal elimination and have led to many studies investigating their dose optimization. Area covered: This review attempts to summarize and compare PK and pharmacodynamics of cisplatin, carboplatin, and oxaliplatin, with an emphasis on differences of dose calculations and opportunities for therapeutic drug monitoring (TDM) in various patient populations. Expert opinion: Although cisplatin and carboplatin can be considered as analogs since they share the same DNA interacting properties, the slower hydrolysis of the latter results in a better safety profile. Carboplatin is the only drug in oncology to be administrated according to a target area under the curve of concentration versus time, considering that its PK variability is almost fully explained by renal function, not by body size. This enables individual dosing based on predicted carboplatin clearance (along with patients renal characteristics) or on actual clearance with TDM, especially in a high-dose protocol.

Therapeutic Drug Monitoring Is a Feasible Tool to Personalize Drug Administration in Neonates Using New Techniques: An Overview on the Pharmacokinetics and Pharmacodynamics in Neonatal Age

Therapeutic drug monitoring (TDM) should be adopted in all neonatal intensive care units (NICUs), where the most preterm and fragile babies are hospitalized and treated with many drugs, considering that organs and metabolic pathways undergo deep and progressive maturation processes after birth. Different developmental changes are involved in interindividual variability in response to drugs. A crucial point of TDM is the choice of the bioanalytical method and of the sample to use. TDM in neonates is primarily used for antibiotics, antifungals, and antiepileptic drugs in clinical practice. TDM appears to be particularly promising in specific populations: neonates who undergo therapeutic hypothermia or extracorporeal life support, preterm infants, infants who need a tailored dose of anticancer drugs. This review provides an overview of the latest advances in this field, showing options for a personalized therapy in newborns and infants.

Over a decade of experience with carboplatin therapeutic drug monitoring in a childhood cancer setting in the United Kingdom

The widely used platinum agent carboplatin represents a good example of an anticancer drug where clear relationships between pharmacological exposure and clinical response and toxicity have previously been shown. Within the setting of childhood cancer, there are defined groups of patients who present a particular challenge when dosing with carboplatin, including neonates and infants, those who are anephric, and poor prognosis patients receiving high-dose chemotherapy. For these groups, nonstandard chemotherapy dosing regimens are currently utilised, often with different approaches between clinical study protocols and between treatment centres. For the treatment of these patient populations in the UK, there is now significant experience in carrying out therapeutic drug monitoring, aiming to consistently achieve target drug exposures, maximise drug efficacy and minimise treatment-related side effects. An ongoing clinical trial is currently providing information on drug exposure for a wide range of anticancer agents in these hard to treat patient populations. In addition to supporting dosing decisions for individual patients, the collection and analysis of these data may allow the development of future dosing regimens. For example, current reduced dosing approaches for neonates and infants based on age or body weight, may well be better replaced by regimens based on a sound pharmacological rationale. The successful use of adaptive carboplatin dosing in childhood cancer should encourage the development of therapeutic drug monitoring approaches more widely in an oncology setting.

The use of pharmacokinetically guided carboplatin chemotherapy in a pre-term infant with neuroblastoma-associated spinal cord compression

Neonatal neuroblastoma may require chemotherapy either due to mass effect or unfavourable cytogenetics. This case focuses on using pharmacokinetic (PK) guided chemotherapy to treat neonatal neuroblastoma. A newborn baby was noted to have left leg immobility. Imaging showed a retroperitoneal tumour with spinal canal extension causing spinal cord compression. PK-guided carboplatin was given after conventionally dosed chemotherapy demonstrated no improvement. After initiation of PK therapy, clinical and radiological improvement was seen. We discuss our decision to use PK-guided chemotherapy despite guidelines recommending weight-based dosing and discuss the benefits in terms of clinical efficacy without increased toxicity.

Results from the UK Children's Cancer and Leukaemia Group study of extracranial germ cell tumours in children and adolescents (GCIII)

BACKGROUND

For extracranial malignant germ cell tumours (MGCTs) in the UK, the GCII study used carboplatin-based chemotherapy (JEb) and demonstrated equivalent survival to cisplatin-containing protocols. GCIII, a single-arm observational study, used new risk stratification, replaced consolidation chemotherapy with a standard number of cycles and introduced surveillance for all stage I MGCTs. Pure teratomas were registered to understand their natural history.

METHODS

Patients with MGCTs were stratified to three risk groups - low risk (LR), intermediate risk (IR) and high risk (HR), using stage and prognostic factors. Patients with alpha fetoprotein (AFP) >10,000 kU/L, stage IV disease (except testis <5 years and all germinomas) or stage II-IV mediastinal tumour were classified HR. Stage I tumours (LR) received chemotherapy only if disease progressed. IR and HR patients received 4 and 6 JEB cycles, respectively. Carboplatin dose was calculated using glomerular filtration rate to give an area under the curve of 7.9 ml/m².min.

RESULTS

Eighty-six patients with MGCTs were enrolled from 2005 to 2009: 59% female, median age, 5.7 years. Twenty-five patients were LR, 21 IR and 38 HR. Seven LR patients had disease progression; all were successfully treated with chemotherapy. Overall survival (OS) for the whole group was 97%; 5-year event-free survival for JEb-treated patients was 92%, and OS, 95%. JEb was well tolerated with no observed significant hearing or renal side-effects. There was no discernible difference in carboplatin dose whether calculated by body surface area or creatinine clearance. Forty-seven patients with teratoma were managed with surgery and one had malignant transformation.

CONCLUSION

Carboplatin-based chemotherapy as part of a risk-stratified approach leads to excellent survival in paediatric MGCTs, minimising potential burden of long-term effects.

Fundamental problems with pediatric adaptive dosing of carboplatin using nuclear-medicine-based estimates of renal function

BACKGROUND

Carboplatin is often adaptively dosed based on glomerular filtration rate (GFR), usually estimated by nuclear medicine tests. At least five pediatric adaptive dosing formulas have been developed. In an effort to standardize dosing in Children's Oncology Group protocols, we explored methodologic variation in GFR estimation and adaptive-dosing formula performance.

PROCEDURE

Nuclear medicine GFR data from published series of ≥100 children with cancer were compared. Data from patients for whom body surface area, weight, GFR, and tracer half-life were available were used to compare formulas.

RESULTS

Differences in methods used to estimate GFR in children with cancer resulted in highly variable population results, with median GFRs ranging from 96 to 150 mL/min/1.73m² . The choice of adaptive formula had a major impact on calculated dose. When targeting an area under the curve of 7.9 mg/mL • min, the median difference between the formula yielding the lowest and highest carboplatin dose for individual subjects was 289 (range 96-1 737) mg/m² .

CONCLUSIONS

Wide variation in GFR obtained with nuclear-medicine-based tests in children with cancer primarily results from systematic methodologic errors. Formulas for calculating carboplatin dose produce additional and substantial variation that may place children with cancer at unnecessary risk for excessive toxicity or underdosing. These findings indicate a need for the development of a uniform, validated method for GFR determination in children that should be utilized in all centers. Currently, adaptive dosing of carboplatin based on GFR has serious limitations and in most clinical settings should arguably not be used in place of body-surface-area-based dosing.

Clinical and genetic associations for carboplatin-related ototoxicity in children treated for retinoblastoma: A retrospective noncomparative single-institute experience

BACKGROUND

Children with retinoblastoma treated with carboplatin chemotherapy risk moderate to severe, irreversible hearing loss. Based on published evidence, we hypothesized that ototoxicity risk is associated with clinical parameters and variants in candidate genes in drug metabolism pathways (methyltransferases [thiopurine S-methyltransferase, TPMT] and [catechol-O-methyltransferase, COMT], and drug transporter ABCC3).

PROCEDURE

We retrospectively reviewed clinical records of patients with retinoblastoma treated with carboplatin chemotherapy regarding age (at diagnosis and chemotherapy initiation), chemotherapy sessions (cycles number, drug doses, and cumulative carboplatin dose), and hearing loss (defined as ototoxicity ≥grade 2 by at least one classification system). Blood samples were genotyped for genetic variants in TPMT (rs12201199, rs1800460), COMT (rs4646316, rs9332377), and ABCC3 (rs1051640) by quantitative PCR and confirmed by allele-specific PCR. Univariate statistical tests, receiver-operating characteristic analysis, and Kaplan-Meier curves were used to examine the association between hearing loss, clinical factors, and variants in candidate genes.

RESULTS

Audiometric data and stored DNA were available for 71 patients with retinoblastoma (88% carried an RB1 pathogenic variant allele). Median carboplatin cumulative dose was 1,400 mg/m² (260-5,148 mg/m² ). Ototoxicity occurred in 18 patients (25%), strongly associated with age at diagnosis (P = 0.01) and age at chemotherapy initiation (OR = 4.99, P = 0.008). The highest likelihood ratio of hearing loss was associated with chemotherapy initiation <4.25 months of age. Ototoxicity was not associated with any tested genetic variants.

CONCLUSIONS

We observed a 25% prevalence of ototoxicity in patients with retinoblastoma treated with carboplatin, higher than previously published. Age at chemotherapy initiation was associated with carboplatin-induced ototoxicity, with children <4.25 months of age at highest risk.

Investigating the potential impact of dose banding for systemic anti-cancer therapy in the paediatric setting based on pharmacokinetic evidence

Background

To make systemic anti-cancer therapy (SACT) preparation more practicable, dose-banding approaches are currently being introduced in many clinical centres. The present study aimed to determine the potential impact of using recently developed National Health Service in England (NHSE) dose-banding tables in a paediatric setting.

Methods

Using pharmacokinetic parameters obtained from 385 drug administrations in 352 children aged from 1 month to 18 years, treated with five drugs (dactinomycin, busulfan, carboplatin, cyclophosphamide and etoposide), individual exposures (area under the plasma drug concentration versus time curve; AUC) obtained using doses rounded according to the published NHSE tables were calculated and compared with those obtained by standard dose calculation methods.

Results

For all five drugs, the relative variation between the NHSE dose and the recommended dose (RecDose) (standard individually calculated dose) was between −6% and +5% as expected. In terms of AUC, there was no statistically significant difference in precision between exposures obtained by the RecDose and those obtained with dose banding (absolute value of relative difference 15–34%).

Conclusion

Based on pharmacokinetic data for these five drugs, the results generated support the implementation of NHSE dose-banding tables. Indeed, inter-patient variability in drug clearance and exposure far outweighs the impact of relatively small drug dose changes associated with dose banding.

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The potential impact of using dose-banding tables in the setting of childhood cancer has been investigated.

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In 352 children receiving five anticancer drugs no difference was found in exposures using dose banding or recommended doses.

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Results generated support the implementation of National Health Service in England dose-banding tables.

Monitoring neonates for ototoxicity

OBJECTIVES

Neonates admitted to the neonatal intensive care unit (NICU) are at greater risk of permanent hearing loss compared to infants in well mother and baby units. Several factors have been associated with this increased prevalence of hearing loss, including congenital infections (e.g. cytomegalovirus or syphilis), ototoxic drugs (such as aminoglycoside or glycopeptide antibiotics), low birth weight, hypoxia and length of stay. The aetiology of this increased prevalence of hearing loss remains poorly understood.

DESIGN

Here we review current practice and discuss the feasibility of designing improved ototoxicity screening and monitoring protocols to better identify acquired, drug-induced hearing loss in NICU neonates.

STUDY SAMPLE

A review of published literature.

CONCLUSIONS

We conclude that current audiological screening or monitoring protocols for neonates are not designed to adequately detect early onset of ototoxicity. This paper offers a detailed review of evidence-based research, and offers recommendations for developing and implementing an ototoxicity monitoring protocol for young infants, before and after discharge from the hospital.

Adaptive dosing of anticancer drugs in neonates: facilitating evidence-based dosing regimens

Purpose

Selection of the most appropriate chemotherapy dosing regimens for neonates treated within the first weeks of life represents a significant clinical dilemma. Due to a lack of information relating to the clinical pharmacology of anticancer drugs in these challenging patients, current dosing guidelines are based on limited scientific rationale. In the current study, we investigate the utilisation of therapeutic drug monitoring approaches in neonates with localised hepatoblastoma, Wilms’ tumour and stage 4S neuroblastoma, being treated with widely used anticancer drugs.

Methods

Plasma concentrations of cisplatin, vincristine, etoposide and carboplatin were quantified in two neonates being treated within the first 3 weeks of life and in a 32-week preterm infant treated at a gestational age of 40 weeks. Therapeutic drug monitoring was carried out where appropriate, based on the pharmacokinetic data obtained in conjunction with clinical response and toxicity.

Results

Treatment of a child aged 2 weeks with a recommended cisplatin dose reduction for weight to 1.8 mg/kg resulted in achievement of unbound cisplatin plasma concentrations of 0.01–0.08 µg/mL, markedly lower than exposures previously reported in infants and older children. A dose increase to 2.7 mg/kg was implemented, leading to the achievement of levels more in-line with those previously reported. This increased dose level was well tolerated over six courses of treatment, resulting in a good response to cisplatin monotherapy and the patient remains in remission at 3.5 years. In contrast, a 50 % vincristine dose reduction for weight in a 3-week-old neonate resulted in plasma concentrations comparable to levels observed in older children, leading to successful treatment and continued remission at 2 years. In a third patient, etoposide and carboplatin clearance values normalised to body weight were comparable to those reported in older children, resulting in comparatively lower exposures following reduced dosing.

Conclusions

The current report provides unique data on the pharmacokinetics of several widely used anticancer drugs in neonates treated within the first few weeks of life. The provision of these data acts as a useful reference point to support future dosing decisions to be made by clinicians in the treatment of these challenging patients.

A mini review on pregnant mothers with cancer: A paradoxical coexistence

The diagnosis of cancer during pregnancy at least in the Western world is a rare phenomenon, but this might be raised into the future due to late pregnancies in the modern societies. The coexistence of pregnancy and cancer implicates numerous medical, ethical, psychological and sometimes religious issues between the mother, the family and the treating physician. Breast, cervical cancer, melanoma and lymphoma are the most common malignancies diagnosed during pregnancy. Diagnostic or therapeutic irradiation requires careful application, whereas systemic chemotherapy is not allowed during the first trimester of pregnancy due to lethal or teratogenic effects as well as to congenital malformations. In some gestational cancers, tumor cells can invade the placenta or the fetus.