Investigating the Experiences of Childhood Cancer Patients and Parents Participating in Optional Nontherapeutic Clinical Research Studies in the UK.

BACKGROUND: While the majority of childhood cancer clinical trials are treatment related, additional optional research investigations may be carried out that do not directly impact on treatment. It is essential that these studies are conducted ethically and that the experiences of families participating in these studies are as positive as possible. METHODS: A questionnaire study was carried out to investigate the key factors that influence why families choose to participate in optional nontherapeutic research studies, the level of understanding of the trials involved, and the experiences of participation. RESULTS: A total of 100 participants from six UK centers were studied; 77 parents, 10 patients >16 years, and 13 patients aged 8-15 years. Ninety-seven percent of parents and 90% of patients felt that information provided prior to study consent was of the right length, with 52% of parents and 65% of patients fully understanding the information provided. Seventy-four percent of parents participated in research studies in order to "do something important", while 74% of patients participated "to help medical staff". Encouragingly, <5% of participants felt that their clinical care would be negatively affected if they did not participate. Positive aspects of participation included a perception of increased attention from medical staff. Negative aspects included spending longer periods in hospital and the requirement for additional blood samples. Ninety-six percent of parents and 87% of patients would participate in future studies. CONCLUSIONS: The study provides an insight into the views of childhood cancer patients and their parents participating in nontherapeutic clinical research studies. Overwhelmingly, the findings suggest that participation is seen as a positive experience.

'Acceptability' of a new oral suspension formulation of mercaptopurine in children with acute lymphoblastic leukaemia.

AIM: The aim of this questionnaire-based survey was to determine the 'acceptability' of Xaluprine®, a new oral liquid formulation of mercaptopurine, when administered chronically to children during the maintenance treatment phase of acute lymphoblastic leukaemia. PATIENTS AND METHODS: This was a single centre survey of children (aged 3 to 16 years) and their parents at a routine follow-up visit during the maintenance phase of acute lymphoblastic leukaemica treatment. The questionnaire probed for their views on overall acceptability such as taste, smell, incidences of vomiting, ease and willingness to take Xaluprine® on a daily basis, and utilised a 5-point facial hedonic scale (1 = bad, 5 = good) as well as open/closed questions. RESULTS: Twenty-two children were recruited; 17 (77%) scored taste between 3 and 5 ('okay' to 'good') and 20 (91%) scored smell between 3 and 5. Only four children (18%) reported an aftertaste. Of the five children (23%) who scored taste as 1 or 2 ('bad'), three found taking all oral medicines difficult. Six children (27%) reported vomiting, but this was not considered related to Xaluprine®. Seven children (32%) sometimes complained that they did not want to take Xaluprine®; 15 (68%) never complained. In response to the question, 'How easy is it for you to take Xaluprine®?' 18 children (82%) reported that it was 'Easy all the time.' This was more favourable than other oral liquid medicines that they were taking concurrently. CONCLUSION: The results of this survey show that Xaluprine® has good overall acceptability in the paediatric population and suggests that Xaluprine® is an important, alternative, age-appropriate formulation of mercaptopurine.

Glomerular toxicity persists 10 years after ifosfamide treatment in childhood and is not predictable by age or dose.

BACKGROUND: This prospective longitudinal single institution cohort study evaluated the natural history of and risk factors for chronic nephrotoxicity 10 years after ifosfamide treatment in childhood. PROCEDURE: Twenty-five patients (16 males) treated with ifosfamide were investigated at end of treatment (End), 1 and 10 years later. Glomerular filtration rate (GFR), serum phosphate (PO4) and bicarbonate (HCO3) and renal tubular threshold for phosphate (Tmp/GFR) were measured, and total nephrotoxicity score (Ns) graded. RESULTS: More patients had a low GFR at 1 (72%) and 10 (50%) years than at End (26%) (P = 0.006 for End vs. 1 year). Electrolyte supplementation requirements for tubular toxicity resolved by 10 years (0% vs. 32% at End and 24% at 1 year; both P < 0.05). At 10 years, 17% of patients had moderate overall nephrotoxicity and 13% clinically significant reduction of GFR (<60 ml/min/1.73 m2). Neither dose nor age at treatment predicted any measure of toxicity at 10 years or reduced GFR at any timepoint. Higher cumulative ifosfamide dose correlated with greater tubular and overall nephrotoxicity at End and/or 1 year (P < 0.05 for each of PO4, HCO3, Tmp/GFR, Ns), but age at treatment did not differ between patients with normal or abnormal results. CONCLUSIONS: Although clinically significant tubular toxicity had resolved by 10 years, GFR was <60 ml/min/1.73 m2 in 13% of patients, raising concerns about very long-term glomerular function. Higher cumulative dose was associated with greater tubular and overall toxicity at End and 1 year, but not at 10 years. Age at treatment did not predict nephrotoxicity at any timepoint.

Pharmacokinetics of dactinomycin in a pediatric patient population: a United Kingdom Children's Cancer Study Group Study.

PURPOSE: Dactinomycin (actinomycin D) is an antitumor antibiotic used routinely to treat certain pediatric and adult cancers. Despite concerns over the incidence of toxicity, little is known about the pharmacology of dactinomycin. A study was done to investigate dactinomycin pharmacokinetics in children. EXPERIMENTAL DESIGN: Dactinomycin was administered to 31 patients by bolus i.v. infusion, at doses of 0.70 to 1.50 mg/m2. Plasma concentrations were determined by liquid chromatography-mass spectrometry up to 24 hours after drug administration and National Cancer Institute Common Toxicity Criteria was assessed. RESULTS: Pharmacokinetic data analysis suggested that a three-compartment model most accurately reflected dactinomycin pharmacokinetics. However, there was insufficient data available to fully characterize this model. A median peak plasma concentration (Cmax) of 25.1 ng/mL (range, 3.2-99.2 ng/mL) was observed at 15 minutes after administration. The median exposure (AUC0-6), determined in 16 patients with sampling to 6 hours, was 2.67 mg/L.min (range, 1.12-4.90 mg/L.min). After adjusting for body size, AUC0-6 and Cmax were positively related to dose (P = 0.03 and P = 0.04, respectively). Patients who experienced any level of Common Toxicity Criteria grade had a 1.46-fold higher AUC0-6, 95% confidence interval (1.02-2.09). AUC0-6 was higher in patients <40 kg, possibly indicating a greater toxicity risk. CONCLUSIONS: Data presented suggest that dosing of dactinomycin based on surface area is not optimal, either in younger patients in whom the risk of toxicity is greater, or in older patients where doses are capped.

Determination of anti-cancer drug actinomycin D in human plasma by liquid chromatography-mass spectrometry.

Actinomycin D is an anti-cancer drug commonly used in the treatment of paediatric malignancies such as Wilms' tumour, Ewing's sarcoma and rhabdomyosarcoma. Despite its long history of clinical use, little is known about the pharmacokinetics of actinomycin D in humans, largely due to problems in developing an analytical assay with the required sensitivity to measure relevant clinical concentrations. As actinomycin D treatment in children with cancer is associated with veno-occlusive disease (VOD), and as the dose intensity of actinomycin D treatment has been defined as a significant risk factor for the development of this potentially life-threatening hepatic toxicity, pharmacokinetic studies of actinomycin D may be beneficial in optimizing treatment with this drug. In order to investigate this issue, we developed a sensitive liquid chromatography-mass spectrometry (LC-MS) method for the determination of actinomycin D in human plasma samples. Extraction of analytical samples was carried out with acetonitrile and analysis performed on an API 2000 LC/MS/MS using an internal standard of 7-aminoactinomycin D. A limit of quantitation of 1.0 ng/ml was determined, allowing the reliable measurement of actinomycin D in plasma samples obtained from patients receiving this drug clinically. The method demonstrated good reproducibility, over the calibration curve range of 1.0-100 ng/ml, with intra- and inter-assay precision CVs of 2.7-11.3 and 2.3-7.8%, respectively. Accuracy data showed relative errors of 2.0-16.4 and 10.4-15.2% for intra-assay (n=10) and inter-assay (n=7) experiments, respectively. Initial results of actinomycin D pharmacokinetics in paediatric patients are shown.

Persistent nephrotoxicity during 10-year follow-up after cisplatin or carboplatin treatment in childhood: relevance of age and dose as risk factors.

PURPOSE: The long-term outcome of platinum-induced nephrotoxicity is unknown. This prospective single-centre longitudinal cohort study evaluated long-term changes following treatment in childhood. METHODS: 63 children treated with platinum (27 cisplatin, 24 carboplatin and 12 both) were studied at the end of treatment (End), 1 year and 10 years later. No child received ifosfamide. Glomerular filtration rate (GFR), serum calcium and magnesium (Mg) were measured, and total nephrotoxicity score (N(s)) was graded. RESULTS: There was no significant overall change in renal function over time in any treatment group (cisplatin, carboplatin or combined). Apart from marginally reduced median GFR (84 ml/min/1.73 m(2)) and Mg (0.68 mmol/l) at End of cisplatin, median GFR, Ca and Mg were normal at all times in each group. At 10 years, GFR was <60 ml/min/1.7 3m(2) in 11%, N(s) grade was severe in 15% and oral Mg supplements were required in 7% cisplatin patients. After cisplatin, older age at treatment was correlated with lower GFR at 10 years (p=0.005), and higher N(s) at End and 10 years (both p=0.02). After carboplatin treatment, older age was associated with lower GFR at all times, and with higher N(s) at End and 1 year (all p<0.03). Higher cisplatin dose rate (>40 mg/m(2)/day) was associated with higher N(s) at 1 year (p=0.02) and higher carboplatin dose with lower Mg at 1 year and with higher N(s) at 1 and 10 years (all p<0.008). CONCLUSIONS: Platinum nephrotoxicity did not change significantly over 10 years. Its severity was correlated to older age at treatment, and at some time points to higher cisplatin dose rate and higher cumulative carboplatin dose.

Potential clinical impact of taking multiple blood samples for research studies in paediatric oncology: how much do we really know?

Pharmacological studies of anti-cancer agents in children are essential to determine their clinical safety and efficacy, both of which can differ considerably from that observed in adults. However, the potential clinical impact of taking blood samples, in addition to those required for standard clinical practice is commonly a concern for both medical and allied staff and parents. Frequently quoted 'safe limits' of 3%-5% of total blood volume taken on any one study day are not based on published data and may not be acceptable for all patients. This article reviews some of the reasons why clinical pharmacology data for anti-cancer drugs is often lacking in a paediatric patient population, summarises data from a retrospective study investigating the potential impact of repeated blood sampling for research purposes and discusses how this issue may be more systematically addressed in future studies. Research involving children with cancer should be limited to those studies addressing key scientific questions and should be designed to limit both the number and volume of blood samples required.