Impact of body composition on pharmacokinetics of doxorubicin in children: a Glaser Pediatric Research Network study

Nutritional status, body composition and diet quality in children with cancer

During cancer treatment, nutritional status disorders such as malnutrition or obesity affect the tolerance of cancer treatment, quality of life, but also the pharmacokinetics of drugs. It is hypothesized that changes in fat and lean body mass can modify chemotherapy volume distribution, metabolism and clearance. In children with cancer, lean body mass decreases or remains low during treatment and fat mass increases. Body composition is influenced by the cancer itself, aggressive multimodal-therapies, changes in metabolism, unbalanced diet and reduced physical activity. Due to the side effects of treatment, including changes in the sense of taste and smell, nausea, vomiting, diarrhea, and stress, eating according to recommendation for macronutrients and micronutrients is difficult. Research indicates that throughout cancer treatment, the consumption of fruits, vegetables, and dairy products tends to be insufficient, whereas there is an elevated intake of sugar and unhealthy snacks. Children exhibit a preference for high-carbohydrate, salty, and strongly flavored products. This review revealed the importance of body composition and its changes during cancer treatment in children, as well as eating habits and diet quality.

Doxorubicin-induced cardiotoxicity and risk factors

Doxorubicin (DOX) is an anthracycline antibiotic widely used as a chemotherapeutic agent to treat solid tumours and hematologic malignancies. Although useful in the treatment of cancers, the benefit of DOX is limited due to its cardiotoxic effect that is observed in a large number of patients. In the literature, there is evidence that the presence of various factors may increase the risk of developing DOX-induced cardiotoxicity. A better understanding of the role of these different factors in DOX-induced cardiotoxicity may facilitate the choice of the therapeutic approach in cancer patients suffering from various cardiovascular risk factors. In this review, we therefore discuss the latest findings in both preclinical and clinical research suggesting a link between DOX-induced cardiotoxicity and various risk factors including sex, age, ethnicity, diabetes, dyslipidaemia, obesity, hypertension, cardiovascular disease and co-medications.

Reference ranges for body composition indices by dual energy X-ray absorptiometry from the Bone Mineral Density in Childhood Study Cohort

BACKGROUND

Body composition assessment aids evaluation of energy stores and the impact of diseases and interventions on child growth. Current United States pediatric reference ranges from the National Health and Nutrition Examination Survey (NHANES) include 20% of children with obesity, body mass index of ≥95th percentile.

OBJECTIVES

This study aimed to develop dual energy X-ray absorptiometry (DXA) based reference ranges in a diverse cohort with low-obesity prevalence from the Bone Mineral Density in Childhood Study (BMDCS).

METHODS

This is a secondary analysis of a longitudinal, prospective, observational cohort. Healthy children (height and BMI within 3rd to 97th percentiles, ages 5-19 y at enrollment), from 5 United States centers were measured annually for ≤7 visits. Whole body scans were acquired using Hologic scanners. A subsample underwent repeat measurements to determine precision. We generated reference ranges for appendicular and total lean soft tissue mass index (LSTM Index), fat mass index (FMI), and other body composition measures. Resulting curves were compared to NHANES and across subgroups. Sex and age-specific equations were developed to adjust body composition Z-scores for height Z score.

RESULTS

We obtained 9846 scans of 2011 participants (51% female, 22% Black, 17% Hispanic, 48% White, 7% Asian/Pacific Islander, and 6% with obesity). Precision (percent coefficient of variation) ranged from 0.7% to 1.96%. Median and-2 standard deviation curves for BMDCS and NHANES were similar, but NHANES +2 standard deviation LSTM Index and FMI curves were distinctly greater than the respective BMDCS curves. Subgroup differences were more extreme for appendicular LSTM Index-Z (mean ± SD: Asian -0.52 ± 0.93 compared with Black 0.77 ± 0.87) than for FMI-Z (Hispanic 0.29 ± 0.98 compared with Black -0.14 ± 1.1) and were smaller for Z-scores adjusted for height Z-score.

CONCLUSIONS

These reference ranges add to sparse normative data regarding body composition in children and adolescents and are based on a cohort with an obesity prevalence similar to current BMI charts. Awareness of subgroup differences aids in interpreting results.

Deep learning of image-derived measures of body composition in pediatric, adolescent, and young adult lymphoma: association with late treatment effects

OBJECTIVES

The objective of this study was to translate a deep learning (DL) approach for semiautomated analysis of body composition (BC) measures from standard of care CT images to investigate the prognostic value of BC in pediatric, adolescent, and young adult (AYA) patients with lymphoma.

METHODS

This 10-year retrospective, single-site study of 110 pediatric and AYA patients with lymphoma involved manual segmentation of fat and muscle tissue from 260 CT imaging datasets obtained as part of routine imaging at initial staging and first therapeutic follow-up. A DL model was trained to perform semiautomated image segmentation of adipose and muscle tissue. The association between BC measures and the occurrence of 3-year late effects was evaluated using Cox proportional hazards regression analyses.

RESULTS

DL-guided measures of BC were in close agreement with those obtained by a human rater, as demonstrated by high Dice scores (≥ 0.95) and correlations (r > 0.99) for each tissue of interest. Cox proportional hazards regression analyses revealed that patients with elevated subcutaneous adipose tissue at baseline and first follow-up, along with patients who possessed lower volumes of skeletal muscle at first follow-up, have increased risk of late effects compared to their peers.

CONCLUSIONS

DL provides rapid and accurate quantification of image-derived measures of BC that are associated with risk for treatment-related late effects in pediatric and AYA patients with lymphoma. Image-based monitoring of BC measures may enhance future opportunities for personalized medicine for children with lymphoma by identifying patients at the highest risk for late effects of treatment.

KEY POINTS

• Deep learning-guided CT image analysis of body composition measures achieved high agreement level with manual image analysis. • Pediatric patients with more fat and less muscle during the course of cancer treatment were more likely to experience a serious adverse event compared to their clinical counterparts. • Deep learning of body composition may add value to routine CT imaging by offering real-time monitoring of pediatric, adolescent, and young adults at high risk for late effects of cancer treatment.

Impact of single-nucleotide variants and nutritional status on population pharmacokinetics of Doxorubicin, and its effect on cardiotoxicity in children with leukemia

PURPOSE

 Doxorubicin is an important antineoplastic agent with wide interindividual variability in response to treatment and in its cardiotoxic effects. To determine the effect of genotypic status of three single-nucleotide variants in ABCC1, NCF4, and CBR3 genes and nutritional status assessed by body mass index, on the population pharmacokinetics of Doxorubicin and its cardiotoxic effects in pediatric patients with leukemia.

PATIENTS AND METHODS

Seventy pediatric patients treated with Doxorubicin were studied, in which 189 biological samples were obtained to determine Doxorubicin concentrations (1 to 3 samples per patient) at different times, for 20 h.

RESULTS

Low body mass index and age ≤ 7 years were associated with decreased clearance of Doxorubicin, and female gender was associated with increased clearance of Doxorubicin. Low BMI and low height were associated with a decrease and increase, respectively, in the intercompartmental clearance (Q) of Doxorubicin. TT homozygosity of the single-nucleotide variant rs3743527 of the ABCC1 gene was associated with an increase in clearance and decreased area under the curve, AA homozygosity of the single-nucleotide variant rs1883112 of the NCF4 gene was associated with a decrease in the volume of distribution in the peripheral compartment (V2), and GG homozygosity of CBR3 rs1056892 with increasing area under the curve.

CONCLUSION

Some covariates studied are directly related to the increase or decrease of the pharmacokinetic parameters of Doxorubicin. Decreased clearance, V2, and increased area under the curve were associated with systolic dysfunction, and decreased Q and V2 were associated with diastolic dysfunction. These results may contribute to the effective and safe use of Doxorubicin in pediatric patients with leukemia.

Pilot study on the effect of supplementation with long-chain ω-3 polyunsaturated fatty acids on body composition in children with acute lymphoblastic leukemia: randomized clinical trial

BACKGROUND

N-3 polyunsaturated fatty acids (LCPUFA-ω3), particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) might have beneficial effects on lean mass and fat mass synthesis.

OBJECTIVE

To investigate the effect of LCPUFA-ω3 supplementation on body composition changes in children with acute lymphoblastic leukemia (ALL) at remission and three months (3 mo) after supplementation.

METHODS

This randomized controlled trial enrolled 72 children (3-13 y) with newly diagnosed ALL (placebo group [500 mg sunflower oil]: 36 patients; LCPUFA-ω3 group [225 mg DHA, 45 mg EPA]: 36 patients). LCPUFA-ω3 was administered at 0.100 g/kg of body weight/day for 3 mo. Both groups were provided with an oral milkshake supplement.

MAIN OUTCOMES AND MEASURES

Body composition was measured at diagnosis, remission, and 3 months after supplementation by dual-energy X-ray absorptiometry (DXA). Red blood cell fatty acid analyses were performed with gas chromatography. Student's t test compared the percentage changes in body weight, total body fat percentage (TBFP), and lean body mass (LBM) between the groups. The Mann-Whitney U test was used to compare the groups, and the Friedman range test and Wilcoxon signed rank test were used for intratreatment comparisons. Spearman correlation coefficients were calculated for LBM and erythrocyte LCPUFA-ω3 content.

RESULTS

LBM decreased significantly in both groups. This loss was greater in the placebo group than in the LCPUFA-ω3 group at remission (p = 0.044) and at 3 months of supplementation (p = 0.039). There were significant and progressive increases in DHA and EPA concentrations in the LCPUFA-ω3 group (p < 0.001). LBM at remission was directly correlated with increased DHA (r = 0.487, p = 0.034) and EPA (r = 0.499, p = 0.030) erythrocytes in the LCPUFA-ω3 group.

CONCLUSION

At ALL diagnosis and during the first three months of treatment, 100 mg/kg of body weight/d DHA and EPA decreased LBM loss and allowed the incorporation of fatty acids into cell membranes (clinicaltriasl.gov #: NCT01051154).

Pharmacokinetics of cancer therapeutics and energy balance: the role of diet intake, energy expenditure, and body composition

Energy balance accounts for an individual's energy intake, expenditure, and storage. Each aspect of energy balance has implications for the pharmacokinetics of cancer treatments and may impact an individual's drug exposure and subsequently its tolerance and efficacy. However, the integrated effects of diet, physical activity, and body composition on drug absorption, metabolism, distribution, and excretion are not yet fully understood. This review examines the existing literature on energy balance, specifically the role of dietary intake and nutritional status, physical activity and energy expenditure, and body composition on the pharmacokinetics of cancer therapeutics. As energy balance and pharmacokinetic factors can be influenced by age-related states of metabolism and comorbidities, this review also explores the age-related impact of body composition and physiologic changes on pharmacokinetics among pediatric and older adult populations with cancer.

Constructing 3D In Vitro Models of Heterocellular Solid Tumors and Stromal Tissues Using Extrusion-Based Bioprinting

Malignant tumor tissues exhibit inter- and intratumoral heterogeneities, aberrant development, dynamic stromal composition, diverse tissue phenotypes, and cell populations growing within localized mechanical stresses in hypoxic conditions. Experimental tumor models employing engineered systems that isolate and study these complex variables using in vitro techniques are under development as complementary methods to preclinical in vivo models. Here, advances in extrusion bioprinting as an enabling technology to recreate the three-dimensional tumor milieu and its complex heterogeneous characteristics are reviewed. Extrusion bioprinting allows for the deposition of multiple materials, or selected cell types and concentrations, into models based upon physiological features of the tumor. This affords the creation of complex samples with representative extracellular or stromal compositions that replicate the biology of patient tissue. Biomaterial engineering of printable materials that replicate specific features of the tumor microenvironment offer experimental reproducibility, throughput, and physiological relevance compared to animal models. In this review, we describe the potential of extrusion-based bioprinting to recreate the tumor microenvironment within in vitro models.

Association between body mass index at diagnosis and outcomes in Chinese children with newly diagnosed acute lymphoblastic leukemia

PURPOSE

Studies of the association between body mass index (BMI) at diagnosis and treatment outcome in children with acute lymphoblastic leukemia (ALL) have yielded inconsistent results. Hence, we conducted a retrospective study in a large cohort of Chinese children with ALL treated with contemporary protocols.

PATIENTS AND METHODS

A total of 1437 children (62.1% male; median age at diagnosis 5.7 years, range: 2.3-16.3 years) were enrolled in two consecutive clinical trials at the Shanghai Children's Medical Center. The rates of overall survival, event-free survival, relapse, treatment-related mortality, and adverse events were compared among patients who were underweight (BMI < 5th percentile), at a healthy weight (5th to 85th percentile), overweight (>85th to <95th percentile), and obese (≥95th percentile).

RESULTS

At diagnosis, 91 (6.3%) patients were underweight, 1070 (74.5%) were at a healthy weight, 91 (6.3%) were overweight, and 185 (12.9%) were obese. No significant association was found between weight status and 5-year overall survival, event-free survival, or relapse in the overall cohort. When analyzed as a continuous variable, a higher BMI Z-score was associated with treatment-related mortality (hazard ratio 1.33 (95% confidence interval [CI], 1.05-1.68%), p = 0.02). The treatment-related mortality rate was higher in the overweight (5.5%, 95% CI 0.8-10.2%) and obese (3.2%, 95% CI 0.6-5.8%) groups compared with the underweight (0.0%) and healthy-weight groups (1.9%, 95% CI 1.1-2.7%; p = 0.04). Multivariable analysis showed that children who were overweight had a higher risk of treatment-related mortality (hazard ratio 3.8, 95% CI 1.3-11.4).

CONCLUSION

While body weight status was not associated with event-free survival or overall survival, overweight patients were at higher risk of treatment-related mortality.

Population pharmacokinetics of doxorubicin: A systematic review

Because of the high interindividual pharmacokinetic variability, several population pharmacokinetic (PopPK) models of doxorubicin (DOX) were developed to characterize factors influencing such variability. However, significant predictors for DOX pharmacokinetics identified using PopPK models varied across studies. Thus, this review aims to summarize PopPK models of DOX and its metabolites (if any) as well as significant covariates influencing DOX (and its metabolites) pharmacokinetic variability. A systematic search from PubMed, CINAHL Complete, Science Direct, and SCOPUS databases identified 503 studies. Of these, 16 studies met the inclusion criteria and were included in this review. DOX pharmacokinetics was described with two- or three-compartment models. Most studies found a significant increase in DOX clearance with an increase in body surface area from the median value of 1.8 m² . Moreover, this review identified that while a 10-year increase in patient age resulted in a decrease in DOX clearance in adults and the elderly, younger children had lower DOX clearance compared to older children. Further, low DOX exposure was observed in pregnant women, and thus dosage adjustment is required. Concerning model applicability, predictive performance assessment of these published models should be performed before implementing such models in clinical practice.

Chemotherapy and Anticancer Drugs Adjustment in Obesity: A Narrative Review

BACKGROUND

Obese individuals have higher rates of cancer incidence and cancer- related mortality. The worse chemotherapy outcomes observed in this subset of patients are multifactorial, including the altered physiology in obesity and its impact on pharmacokinetics, the possible increased risk of underdosing, and treatment-related toxicity.

AIMS

The present review aimed to discuss recent data on physiology, providing just an overall perspective and pharmacokinetic alterations in obesity concerning chemotherapy. We also reviewed the controversies of dosing adjustment strategies in adult and pediatric patients, mainly addressing the use of actual total body weight and ideal body weight.

METHODS

This narrative review tried to provide the best evidence to support antineoplastic drug dosing strategies in children, adolescents, and adults.

RESULTS

Cardiovascular, hepatic, and renal alterations of obesity can affect the distribution, metabolism, and clearance of drugs. Anticancer drugs have a narrow therapeutic range, and variations in dosing may result in either toxicity or underdosing. Obese patients are underrepresented in clinical trials that focus on determining recommendations for chemotherapy dosing and administration in clinical practice. After considering associated comorbidities, the guidelines recommend that chemotherapy should be dosed according to body surface area (BSA) calculated with actual total body weight, not an estimate or ideal weight, especially when the intention of therapy is the cure.

CONCLUSION

The actual total body weight dosing appears to be a better approach to dosing anticancer drugs in both adults and children when aiming for curative results, showing no difference in toxicity and no limitation in treatment outcomes compared to adjusted doses.

Lean Body Mass and Total Body Weight Versus Body Surface Area as a Determinant of Docetaxel Pharmacokinetics and Toxicity

AIM

This study examined whether anthropometric and body composition parameters such as body surface area (BSA), lean body mass (LBM), and total body weight (TBW) are correlated with docetaxel clearance and exposure by analyzing area under the curve. In addition, LBM, TBW, and a fixed dose were compared with BSA as dosing parameters for dose individualization of docetaxel.

METHODS

Thirty-six patients receiving docetaxel chemotherapy for breast or metastatic castration-resistant prostate carcinoma were included. Before treatment, LBM was measured using a dual-energy X-ray absorptiometry scanner. Blood samples were collected up to 180 minutes after dosing to analyze docetaxel concentrations and determine individual pharmacokinetic parameters.

RESULTS

No significant correlations were found between docetaxel clearance and the anthropometric and body composition variables (BSA, LBM, and TBW). The area under the curve was significantly but poorly correlated with BSA [r = 0.452 ( P = 0.016)] and TBW [r = 0.476 ( P = 0.011)]. The mean absolute percentage error and mean error of simulated dosing based on LBM and fixed dosing were not significantly different from those of BSA. For TBW, only mean absolute percentage error was significantly higher compared with dosing based on BSA (24.1 versus 17.1, P = 0.001).

CONCLUSIONS

There was no clinically relevant correlation between docetaxel pharmacokinetics and the anthropometric and body composition variables BSA, LBM, and TBW. Therefore, dose individualization of docetaxel based on LBM, TBW, or fixed dosing cannot be recommended over BSA-based dosing.

Quantification of chemotherapy-induced changes in body composition in pediatric, adolescent, and young adult lymphoma using standard of care CT imaging

OBJECTIVES

The objective of this study was to use computed tomography (CT) imaging to quantify chemotherapy-induced changes in body composition (BC) in pediatric, adolescent, and young adult (AYA) patients with lymphoma and to compare image-derived changes in BC measures to changes in traditional body mass index (BMI) measures.

METHODS

Skeletal muscle (SkM), subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT) volumes were manually segmented using low-dose CT images acquired from a 10-year retrospective, single-site cohort of 110 patients with lymphoma. CT images and BMI percentiles (BMI%) were acquired from baseline and first therapeutic follow-up. CT image segmentation was performed at vertebral level L3 using 5 consecutive axial CT images.

RESULTS

CT imaging detected significant treatment-induced changes in BC measures from baseline to first follow-up time points, with SAT and VAT significantly increasing and SkM significantly decreasing. BMI% measures did not change from baseline to first follow-up and were not significantly correlated with changes in image-derived BC measures. Patients who were male, younger than 12 years old, diagnosed with non-Hodgkin's lymphoma, and presented with stage 3 or 4 disease gained more adipose tissue and lost more SkM in response to the first cycle of treatment compared to their clinical counterparts.

CONCLUSIONS

Standard of care CT imaging can quantify treatment-induced changes in BC that are not reflected by traditional BMI assessment. Image-based monitoring of BC parameters may offer personalized approaches to lymphoma treatment for pediatric and AYA patients by guiding cancer treatment recommendations and subsequently enhance clinical outcomes.

KEY POINTS

• Standard of care low-dose CT imaging quantifies chemotherapy-induced changes in body composition in pediatric, adolescent, and young adults with lymphoma. • Body mass index could not detect changes in body composition during treatment that were quantified by CT imaging. • Pediatric and AYA patients who were male, younger than 12 years old, and diagnosed with non-Hodgkin's lymphoma, and presented with stage 3 or 4 disease gained more adipose tissue and lost more skeletal muscle tissue in response to the first cycle of treatment compared to their clinical counterparts.

Prognostic impact of sarcopenia in children with cancer: a focus on the psoas muscle area (PMA) imaging in the clinical practice

Skeletal muscle plays a crucial part in the metabolic and inflammatory response. "Sarcopenia", defined as a pathological condition of reduced strength, quantity and quality of skeletal muscle mass, may often develop in the young age as the secondary consequence of a systemic inflammatory illness, like cancer. In children with cancer, sarcopenia is a common finding, playing a negative role in their prognosis. However, its prevalence in clinical practice is underestimated. Moreover, several pre- and post-natal factors may influence skeletal muscle development in childhood, making the issue more complex. Given the frequent use of radiological imaging in clinical practice, prompt analysis of body composition is feasible and able to detect the presence of reduced fat-free mass (FFM) among pediatric patients with cancer. We discuss the recent advances in the study of body composition in children with cancer, dissecting the role of the psoas muscle area (PMA) measure, obtained from computerized tomography (CT) or magnetic resonance images (MRI) as a marker of sarcopenia in this setting. Since age and sex-specific percentile curves for PMA and a PMA z-scores calculator are available online, such a tool may be useful to simply detect and treat sarcopenia and its consequences in childhood cancer.

The effects of pazopanib on doxorubicin pharmacokinetics in children and adults with non-rhabdomyosarcoma soft tissue sarcoma: a report from Children's Oncology Group and NRG Oncology study ARST1321

PURPOSE

The use of tyrosine kinase inhibitors for the treatment for soft tissue sarcomas is increasing given promising signals of activity in a variety of tumor types. The recently completed study in non-rhabdomyosarcoma soft tissue sarcomas, ARST1321, demonstrated that the addition of pazopanib to neoadjuvant ifosfamide, doxorubicin, and radiation improved the pathological near complete response rate compared with chemoradiotherapy alone. Pharmacokinetic (PK) evaluation of doxorubicin with pazopanib has not been previously reported. As an exploratory aim, doxorubicin PK data were collected during the dose-finding phase of the study in patients receiving chemotherapy and pazopanib to assess the effect of pazopanib on doxorubicin PK parameters.

METHODS

Blood samples were collected during cycle 2 (week 4) of chemotherapy at the following time points from doxorubicin administration: predose, 5, 30, and 60 min, and 2, 4, 8, 24 ± 3, and 48 ± 3 h after dosing. The population pharmacokinetic and individual post hoc estimates of doxorubicin and doxorubicinol were determined by nonlinear mixed-effects modeling.

RESULTS

There were 52 doxorubicin and doxorubicinol samples from 7 individuals in this study (median age: 17 years; range 14-23). The doxorubicin clearance was 26.9 (16.1, 36.4, and 33.9) L/h/m2 (post hoc median and range) and 25.8 (23.3%) L/h/m2 [population estimate and IIV (CV%)]. The doxorubicinol apparent clearance was 67.5 (18.2, 1701) L/h/m2 (post hoc median and range) and 58.7 (63.7%) L/h/m2 [population estimate and IIV (CV%)].

CONCLUSION

The PK data of seven patients treated on ARST1321 is consistent with previously reported population and post hoc doxorubicin clearance and doxorubicinol apparent clearance estimates, showing that the addition of pazopanib does not significantly alter doxorubicin pharmacokinetics. These data support the safety of administration of pazopanib with doxorubicin-containing chemotherapy.

Characterizing Pharmacokinetics in Children With Obesity-Physiological, Drug, Patient, and Methodological Considerations

Childhood obesity is an alarming public health problem. The pediatric obesity rate has quadrupled in the past 30 years, and currently nearly 20% of United States children and 9% of children worldwide are classified as obese. Drug distribution and elimination processes, which determine drug exposure (and thus dosing), can vary significantly between patients with and without obesity. Obesity-related physiological changes, such as increased tissue volume and perfusion, altered blood protein concentrations, and tissue composition can greatly affect a drug's volume of distribution, which might necessitate adjustment in loading doses. Obesity-related changes in the drug eliminating organs, such as altered enzyme activity in the liver and glomerular filtration rate, can affect the rate of drug elimination, which may warrant an adjustment in the maintenance dosing rate. Although weight-based dosing (i.e., in mg/kg) is commonly practiced in pediatrics, choice of the right body size metric (e.g., total body weight, lean body weight, body surface area, etc.) for dosing children with obesity still remains a question. To address this gap, the interplay between obesity-related physiological changes (e.g., altered organ size, composition, and function), and drug-specific properties (e.g., lipophilicity and elimination pathway) needs to be characterized in a quantitative framework. Additionally, methodological considerations, such as adequate sample size and optimal sampling scheme, should also be considered to ensure accurate and precise top-down covariate selection, particularly when designing opportunistic studies in pediatric drug development. Further factors affecting dosing, including existing dosing recommendations, target therapeutic ranges, dose capping, and formulations constraints, are also important to consider when undergoing dose selection for children with obesity. Opportunities to bridge the dosing knowledge gap in children with obesity include modeling and simulating techniques (i.e., population pharmacokinetic and physiologically-based pharmacokinetic [PBPK] modeling), opportunistic clinical data, and real world data. In this review, key considerations related to physiology, drug parameters, patient factors, and methodology that need to be accounted for while studying the influence of obesity on pharmacokinetics in children are highlighted and discussed. Future studies will need to leverage these modeling opportunities to better describe drug exposure in children with obesity as the childhood obesity epidemic continues.

Systematic review of gastrostomy complications and outcomes in pediatric cancer and bone marrow transplant

BACKGROUND

Nutrition support is essential in children with cancer, including those undergoing bone marrow transplant (BMT), to reduce the risk of malnutrition and associated deleterious outcomes. Enteral nutrition is more commonly provided via nasogastric than gastrostomy tubes because of safety concerns with the latter in immunocompromised children. This systematic review investigated the incidence and type of complications and outcomes in pediatric cancer patients fed by gastrostomy.

METHODS

Databases were searched for randomized and observational studies investigating the use of any gastrostomy device in children aged <18 years with any cancer diagnosis, including those undergoing BMT. Five cohort and 11 case series studies were included. Owing to clinical heterogeneity, meta-analyses were not performed.

RESULTS

Quality of evidence varied, with five studies judged at serious risk of bias and poor quality; however, the remaining 11 were considered to range from moderate to good quality. Across studies, 54.6% of children developed one or more complications, of which 76.6% were classified as minor, 23.4% major. The most frequent complications included inflammation (52% of episodes), infection (42.1%), leakage (22.3%), and granuloma (21%). Evidence regarding infection rates in cancer/BMT patients compared with other disease states was inconclusive. Gastrostomy feeding was associated with improvement or stabilization of nutrition status in 77%-92.7% of children.

CONCLUSION

Gastrostomy feeding in this population is relatively safe and effective in stabilizing or improving nutrition status throughout treatment. Complications are frequent but mostly minor. Placement requires careful consideration of the complications, benefits, nutrition risk and status at diagnosis, and quality of life.

Consideration of Sex as a Biological Variable in the Development of Doxorubicin Myotoxicity and the Efficacy of Exercise as a Therapeutic Intervention

Doxorubicin (DOX) is an anthracycline antibiotic used to treat a wide variety of hematological and solid tumor cancers. While DOX is highly effective at reducing tumor burden, its clinical use is limited by the development of adverse effects to both cardiac and skeletal muscle. The detrimental effects of DOX to muscle tissue are associated with the increased incidence of heart failure, dyspnea, exercise intolerance, and reduced quality of life, which have been reported in both patients actively receiving chemotherapy and cancer survivors. A variety of factors elevate the probability of DOX-related morbidity in patients; however, the role of sex as a biological variable to calculate patient risk remains unclear. Uncertainty regarding sexual dimorphism in the presentation of DOX myotoxicity stems from inadequate study design to address this issue. Currently, the majority of clinical data on DOX myotoxicity come from studies where the ratio of males to females is unbalanced, one sex is omitted, and/or the patient cohort include a broad age range. Furthermore, lack of consensus on standard outcome measures, difficulties in long-term evaluation of patient outcomes, and other confounding factors (i.e., cancer type, drug combinations, adjuvant therapies, etc.) preclude a definitive answer as to whether differences exist in the incidence of DOX myotoxicity between sexes. This review summarizes the current clinical and preclinical literature relevant to sex differences in the incidence and severity of DOX myotoxicity, the proposed mechanisms for DOX sexual dimorphism, and the potential for exercise training to serve as an effective therapeutic countermeasure to preserve muscle strength and function in males and females.

Is there scope for better individualisation of anthracycline cancer chemotherapy?

Anthracyclines are used to treat solid and haematological cancers, particularly breast cancers, lymphomas and childhood cancers. Myelosuppression and cardiotoxicity are the primary toxicities that limit treatment duration and/or intensity. Cardiotoxicity, particularly heart failure, is a leading cause of morbidity and mortality in cancer survivors. Cumulative anthracycline dose is a significant predictor of cardiotoxicity risk, suggesting a role for anthracycline pharmacokinetic variability. Population pharmacokinetic modelling in children has shown that doxorubicin clearance in the very young is significantly lower than in older children, potentially contributing to their higher risk of cardiotoxicity. A model of doxorubicin clearance based on body surface area and age offers a patient-centred dose-adjustment strategy that may replace the current disparate initial-dose selection tools, providing a rational way to compensate for pharmacokinetic variability in children aged <7 years. Population pharmacokinetic models in adults have not adequately addressed older ages, obesity, hepatic and renal dysfunction, and potential drug-drug interactions to enable clinical application. Although candidate gene and genome-wide association studies have investigated relationships between genetic variability and anthracycline pharmacokinetics or clinical outcomes, there have been few clinically significant reproducible associations. Precision-dosing of anthracyclines is currently hindered by lack of clinically useful pharmacokinetic targets and models that predict cumulative anthracycline exposures. Combined with known risk factors for cardiotoxicity, the use of advanced echocardiography and biomarkers, future validated pharmacokinetic targets and predictive models could facilitate anthracycline precision dosing that truly maximises efficacy and provides individualised early intervention with cardioprotective therapies in patients at risk of cardiotoxicity.

Predicting Chemotherapy-Induced Neutropenia and Granulocyte Colony-Stimulating Factor Response Using Model-Based In Vitro to Clinical Translation

The ability to predict the incidence of chemotherapy-induced neutropenia in early drug development can inform risk monitoring and mitigation strategies, as well as decisions on advancing compounds to clinical trials. In this report, a physiological model of granulopoiesis that incorporates the drug's mechanism of action on cell cycle proliferation of bone marrow progenitor cells was extended to include the action of the cytotoxic agents paclitaxel, carboplatin, doxorubicin, and gemcitabine. In vitro bone marrow studies were conducted with each compound, and results were used to determine the model's drug effect parameters. Population simulations were performed to predict the absolute neutrophil count (ANC) and incidence of neutropenia for each compound, which were compared to results reported in the literature. In addition, using the single agent in vitro study results, the model was able to predict ANC time course in response to paclitaxel plus carboplatin in combination, which compared favorably to the results reported in a phase 1 clinical trial of 46 patients (r2 = 0.70). Model simulations were used to compare the relative risk (RR) of neutropenia in patients with high baseline ANCs for five chemotherapeutic regimens: doxorubicin (RR = 0.59), paclitaxel plus carboplatin combination (RR = 0.079), carboplatin (RR = 0.047), paclitaxel (RR = 0.031), and gemcitabine (RR = 0.013). Finally, the model was applied to quantify the reduced incidence of neutropenia with coadministration of pegfilgrastim or filgrastim, for both paclitaxel and the combination of paclitaxel plus carboplatin. The model provides a framework for predicting clinical neutropenia using in vitro bone marrow studies of anticancer agents that may guide drug development decisions.

The effect of obesity, macronutrients, fasting and nutritional status on drug-metabolizing cytochrome P450s: a systematic review of current evidence on human studies

BACKGROUND

Cytochrome P450s (CYPs) are a class of hemoproteins involved in drug metabolism. It has been reported that body composition, proportion of dietary macronutrients, fasting and nutritional status can interfere with the activity of drug-metabolizing CYPs.

OBJECTIVES

The present systematic review was conducted to summarize the effect of obesity, weight reduction, macronutrients, fasting and malnutrition on the CYP-mediated drug metabolism.

METHODS

PubMed (Medline), Scopus, Embase and Cochrane Library databases and Google Scholar were searched up to June 2020 to obtain relevant studies. The PRISMA guidelines were employed during all steps. Two reviewers independently extracted the information from the included studies. Studies investigating CYPs activity directly or indirectly through pharmacokinetics of probe drugs, were included. Increase in clearance (CL) or decrease in elimination half-life (t½) and area under the curve (AUC) of probe drugs were considered as increase in CYPs activity.

RESULTS

A total of 6545 articles were obtained through searching databases among which 69 studies with 126 datasets fully met the inclusion criteria. The results indicated that obesity might decrease the activity of CYP3A4/5, CYP1A2 and CYP2C9 and increase the activity of CYP2E1. The effect of obesity on CYP2D6 is controversial. Also, weight loss increased CYP3A4 activity. Moreover, CYP1A2 activity was decreased by high carbohydrate diet, increased by high protein diet and fasting and unchanged by malnutrition. The activity of CYP2C19 was less susceptible to alterations compared to other CYPs.

CONCLUSION

The activity of drug-metabolizing CYPs are altered by body composition, dietary intake and nutritional status. This relationship might contribute to drug toxicity or reduce treatment efficacy and influence cost-effectiveness of medical care.

Skeletal muscle and adipose tissue changes in the first phase of treatment of pediatric solid tumors

Body composition is increasingly recognized as an important factor in cancer outcomes. Use of computed tomography (CT) in cancer care provides the opportunity to accurately quantify whole‐body lean and adipose tissues from images at the third lumbar spine. We sought to substantiate the use of routinely captured, single‐slice chest CT images at the thoracic level for evaluation of skeletal muscle, residual lean tissue, and adiposity among pediatric solid tumor patients. We performed a retrospective analysis among children who underwent treatment for a solid tumor at Columbia University Irving Medical Center. Skeletal muscle (SM), residual lean tissue (RLT), and adipose tissue cross‐sectional areas (cm²) were analyzed at diagnosis and at first follow‐up for disease evaluation (6–14 weeks). Imaging analysis was performed utilizing slice‐O‐matic image analysis software. Of the 57 patients identified, 39 had chest CT imaging that included intervertebral level T12‐L1, and 22 also had concurrent imaging at L3. Correlation coefficients between body composition variables at T12‐L1 and L3 were strong (r = 0.93–0.98). Paired t‐test showed a significant decrease in SM (−4.2 ± 8.12, p = 0.003) and RLT (−10.7 ± 28.5, p = 0.025) as well as a trend toward a significant increase in visceral adipose tissue (3.10 ± 9.65, p = 0.052). Univariable analysis demonstrated a significant association between increasing age and increased SM loss (β = −0.496 with SE = 0.194, p = 0.011), and a lack of association between body mass index and body composition changes. We provide the first line of evidence that single‐slice images from routinely obtained chest CT scans provide a simple, readily available mechanism for assessing body composition in pediatric solid tumor patients. Adverse body composition changes were observed, particularly among adolescents and young adults.

Precis: Changes in body composition can be detected via routine CT images in pediatric patients undergoing treatment for solid tumors.

Body Composition in Pediatric Solid Tumors: State of the Science and Future Directions

Sarcopenia (severe skeletal muscle wasting) and sarcopenic obesity (skeletal muscle wasting in the setting of excess fat) have been increasingly recognized as important prognostic indicators in adult oncology. Unfavorable changes in lean and adipose tissue masses manifest early in therapy and are associated with altered chemotherapy metabolism as well as increased treatment-related morbidity and mortality. Existing literature addresses the role of body composition in children with hematologic malignancies; however, data is lacking among solid tumor patients. Advances in imaging techniques for quantification of tissue compartments potentiate further investigation in this highly understudied area of pediatric oncology. The following review presents an in-depth discussion of body composition analysis and its potential role in the care of pediatric solid tumor patients. Integration of body tissue measurement into standard practice has broad clinical implications and may improve quality of life and treatment outcomes in this at-risk population.

Mechanisms by Which Obesity Impacts Survival from Acute Lymphoblastic Leukemia

The prevalence of obesity has steadily risen over the past decades, even doubling in more than 70 countries. High levels of body fat (adiposity) and obesity are associated with endocrine and hormonal dysregulation, cardiovascular compromise, hepatic dysfunction, pancreatitis, changes in drug metabolism and clearance, inflammation, and metabolic stress. It is thus unsurprising that obesity can affect the development of and survival from a wide variety of malignancies. This review focuses on acute lymphoblastic leukemia, the most common malignancy in children, to explore the multiple mechanisms connecting acute lymphoblastic leukemia, obesity, and adipocytes, and the implications for leukemia therapy.

Review of nutritional status, body composition, and effects of antineoplastic drug disposition

The overall survival for children with cancer in high income countries is excellent. However, there are many disparities that may negatively affect survival, which are particularly problematic in low income countries, such as nutritional status at diagnosis and throughout therapy. Nutritional status as well as concomitant foods, supplements, and medications may play a role in overall exposure and response to chemotherapy. Emerging science around the microbiome may also play a role and should be further explored as a contributor to disease progression and therapeutic response. This article highlights some of these issues and proposes additional areas of research relevant to nutritional status and pharmacology that are needed in pediatric oncology.

Pharmacokinetics and population pharmacokinetics in pediatric oncology

Pharmacokinetic research has become increasingly important in pediatric oncology as it can have direct clinical implications and is a crucial component in individualized medicine. Population pharmacokinetics has become a popular method especially in children, due to the potential for sparse sampling, flexible sampling times, computing of heterogeneous data, and identification of variability sources. However, population pharmacokinetic reports can be complex and difficult to interpret. The aim of this article is to provide a basic explanation of population pharmacokinetics, using clinical examples from the field of pediatric oncology, to facilitate the translation of pharmacokinetic research into the daily clinic.

MiRNAs as Novel Adipokines: Obesity-Related Circulating MiRNAs Influence Chemosensitivity in Cancer Patients

Adipose tissue is an endocrine organ, capable of regulating distant physiological processes in other tissues via the release of adipokines into the bloodstream. Recently, circulating adipose-derived microRNAs (miRNAs) have been proposed as a novel class of adipokine, due to their capacity to regulate gene expression in tissues other than fat. Circulating levels of adipokines are known to be altered in obese individuals compared with typical weight individuals and are linked to poorer health outcomes. For example, obese individuals are known to be more prone to the development of some cancers, and less likely to achieve event-free survival following chemotherapy. The purpose of this review was twofold; first to identify circulating miRNAs which are reproducibly altered in obesity, and secondly to identify mechanisms by which these obesity-linked miRNAs might influence the sensitivity of tumors to treatment. We identified 8 candidate circulating miRNAs with altered levels in obese individuals (6 increased, 2 decreased). A second literature review was then performed to investigate if these candidates might have a role in mediating resistance to cancer treatment. All of the circulating miRNAs identified were capable of mediating responses to cancer treatment at the cellular level, and so this review provides novel insights which can be used by future studies which aim to improve obese patient outcomes.

Dexrazoxane preferentially mitigates doxorubicin cardiotoxicity in female children with sarcoma

Objective

We sought to determine how sex and dexrazoxane therapy influence cardiac remodelling in children with sarcoma receiving high-dose doxorubicin.

Methods

In a retrospective cohort of 85 children with sarcoma receiving high-dose doxorubicin, echocardiography measures prior to, early after (within 6 months of doxorubicin completion) and 1 – 2 years after doxorubicin completion were quantified. At each follow-up visit, multivariable, propensity-adjusted linear regression models evaluated dexrazoxane’s effects on changes in left ventricular (LV) shortening fraction (SF), structure, strain and wall stress for subgroups divided by sex. Likelihood ratio tests assessed the interaction between sex and dexrazoxane in determining these changes.

Results

Early after doxorubicin completion, males not treated with dexrazoxane (n = 15) developed increased cavity size and diminished circumferential strain; females (n = 8) developed diminished SF and strain indices, and increased cavity size and wall stress. With dexrazoxane, males (n = 33) demonstrated less deterioration in circumferential strain by 3.4% (95% CI 0.01 to 6.8), and females (n = 29) demonstrated less reduction in SF by 5.7% (95% CI 2.1 to 9.3), and had mitigation of increases in cavity size and wall stress. In interaction analyses, females had greater protection with dexrazoxane with regard to SF (p = 0.019) and cavity size in diastole (p = 0.002) and systole (p ≤ 0.001). These findings largely persisted 1 – 2 years after doxorubicin therapy.

Conclusions

Early, sustained alterations in LV structure and function occur in children with sarcoma after high-dose doxorubicin, with adverse changes and protective effects of dexrazoxane more pronounced in females as compared with males. Dexrazoxane may have sex-specific cardioprotective effects.

Nutritional status and clinical outcomes in pediatric patients with solid tumors : A systematic review of the literature

INTRODUCTION

Nutritional status (NS), defined by undernutrition (body mass index [BMI] <5th percentile) or overnutrition (BMI  ≥ 85th percentile), is a poor prognostic indicator in pediatric oncology patients. The impact of NS has been primarily studied in hematologic malignancies. This review is intended to summarize literature reporting on the association of NS and treatment-related outcomes in pediatric solid tumors.

METHODS

We searched four electronic databases from inception through August 2018 without language restriction, and included studies of children with cancers arising from renal, bone, liver, eye, muscle, vascular, germ cell, and neural crest tissues, reporting on NS as a predictor for toxicity, survival or relapse. Due to data heterogeneity and limited availability of studies, formal statistical analysis was not achievable. Descriptive statistics were summarized in table format.

RESULTS

Of 8,991 reports identified, 75 full-text articles were evaluated, 10 of which met inclusion criteria. Up to 62% of patients were over- or undernourished at diagnosis. Abnormal BMI was associated with worse overall survival in Ewing sarcoma (hazard ratio (HR): 3.46, P = .022), osteosarcoma (HR: 1.6, P < .005), and a trend toward poorer overall survival in rhabdomyosarcoma (HR: 1.70, P = .0596). High BMI in osteosarcoma was associated with increased nephrotoxicity (odds ratio: 2.8, P = .01) and postoperative complications. NS was not a significant predictor of outcomes in other included disease categories.

CONCLUSIONS

Existing literature supports the prognostic significance of NS in pediatric solid tumor patients and underscores the need for prospective studies to better elucidate underlying physiological changes in this population.

Body composition and sarcopenia: The next-generation of personalized oncology and pharmacology?

Body composition has gained increasing attention in oncology in recent years due to fact that sarcopenia has been revealed to be a strong prognostic indicator for survival across multiple stages and cancer types and a predictive factor for toxicity and surgery complications. Accumulating evidence over the last decade has unraveled the "pharmacology" of sarcopenia. Lean body mass may be more relevant to define drug dosing than the "classical" body surface area or flat-fixed dosing in patients with cancer. Since sarcopenia has a major impact on patient survival and quality of life, therapeutic interventions aiming at reducing muscle loss have been developed and are being prospectively evaluated in randomized controlled trials. It is now acknowledged that this supportive care dimension of oncological management is essential to ensure the success of any anticancer treatment. The field of sarcopenia and body composition in cancer is developing quickly, with (i) the newly identified concept of sarcopenic obesity defined as a specific pathophysiological entity, (ii) unsolved issues regarding the best evaluation modalities and cut-off for definition of sarcopenia on imaging, (iii) first results from clinical trials evaluating physical activity, and (iv) emerging body-composition-tailored drug administration schemes. In this context, we propose a comprehensive review providing a panoramic approach of the clinical, pharmacological and therapeutic implications of sarcopenia and body composition in oncology.

Clinical and preclinical evidence of sex-related differences in anthracycline-induced cardiotoxicity

Anthracyclines are very effective chemotherapeutic agents that are widely used to treat pediatric and adult cancer patients. Unfortunately, the clinical utility of anthracyclines is limited by cardiotoxicity. There are several established risk factors for anthracycline-induced cardiotoxicity (AIC), including total cumulative dose, very young and very old age, concomitant use of other cardiotoxic agents, and concurrent mediastinal radiation. However, the role of sex as a risk factor for AIC is not well defined. In pediatric cancer patients, most studies support the notion that female sex is a significant risk factor for AIC. Conversely, there is anecdotal evidence that female sex protects against AIC in adult cancer patients. The lack of consistency in study designs and the different definitions of cardiotoxicity preclude reaching consensus regarding the role of sex as a risk factor for AIC in both pediatric and adult cancer patients. Therefore, more clinical research using reliable techniques such as cardiac magnetic resonance imaging is needed to determine if there truly are sex differences in AIC. In adult preclinical rodent studies, however, there is unequivocal evidence that female sex confers significant protection against AIC, with a possible protective effect of female sex hormones and/or a detrimental role of the male sex hormones. Although findings of these rodent studies may not perfectly mirror the clinical scenario in adult anthracycline-treated cancer patients, understanding the mechanisms of this significant sexual dimorphism may reveal important cardioprotective mechanisms that can be therapeutically targeted.

Simple and rapid monitoring of doxorubicin using streptavidin-modified microparticle-based time-resolved fluorescence immunoassay

Developing a simple analytical method suitable for therapeutic drug monitoring in a clinical setting is key to establishing guidelines on accurate dose administration and the advancement of precision medicine. We devised a simple rapid analytical method through the combination of streptavidin-modified microparticles and a time-resolved fluorescence immunoassay for therapeutic drug monitoring. The analytical performance of this method was investigated and validated using clinical samples. By determination of doxorubicin concentration, the proposed assay has shown a satisfactory linear range of detection (3.8-3000 ng mL-1) with a limit of detection of 3.8 ng mL-1 and an IC50 of 903.9 ng mL-1. The intra and inter-assay coefficients of variation were 4.12-5.72% and 5.48-6.91%, respectively, and the recovery was acceptable. The applicability of the proposed assay was assessed by comparing the determined results with those measured by LC-MS/MS, presenting a satisfactory correlation (R 2 = 0.9868). The proposed assay, which shows satisfactory analytical performance, has great potential for application in the field of TDM in the future.

Limitations of body mass index to assess body composition due to sarcopenic obesity during leukemia therapy

Obesity as defined by body mass index percentile (BMI%) is strongly associated with relapse and poorer survival in childhood ALL. Whether BMI% accurately reflects body fat percentage (BF%) in this population is unknown. We conducted a prospective study assessing body composition during frontline ALL therapy. Dual-energy X-ray absorptiometry measured BF% and lean muscle mass (LMM) at diagnosis, end of Induction, and end of Delayed Intensification. Sarcopenic obesity (gain in BF% with loss of LMM) was surprisingly common during ALL treatment, resulting in poor correlation between changes in BMI% (expressed as Z-score) and BF% overall (r = -0.05) and within patients (r = -0.09). BMI Z-score and BF% changed in opposite directions in >50% of interval assessments. While BMI% at diagnosis is a suitable predictor of obesity/BF% for epidemiological studies, change in BMI% (as expressed as Z-score) does not reflect body composition. Studies evaluating obesity in leukemia should consider using direct measures of body composition.

Chemoresistance: Intricate Interplay Between Breast Tumor Cells and Adipocytes in the Tumor Microenvironment

Excess adipose tissue is a hallmark of an overweight and/or obese state as well as a primary risk factor for breast cancer development and progression. In an overweight/obese state adipose tissue becomes dysfunctional due to rapid hypertrophy, hyperplasia, and immune cell infiltration which is associated with sustained low-grade inflammation originating from dysfunctional adipokine synthesis. Evidence also supports the role of excess adipose tissue (overweight/obesity) as a casual factor for the development of chemotherapeutic drug resistance. Obesity-mediated effects/modifications may contribute to chemotherapeutic drug resistance by altering drug pharmacokinetics, inducing chronic inflammation, as well as altering tumor-associated adipocyte adipokine secretion. Adipocytes in the breast tumor microenvironment enhance breast tumor cell survival and decrease the efficacy of chemotherapeutic agents, resulting in chemotherapeutic resistance. A well-know chemotherapeutic agent, doxorubicin, has shown to negatively impact adipose tissue homeostasis, affecting adipose tissue/adipocyte functionality and storage. Here, it is implied that doxorubicin disrupts adipose tissue homeostasis affecting the functionality of adipose tissue/adipocytes. Although evidence on the effects of doxorubicin on adipose tissue/adipocytes under obesogenic conditions are lacking, this narrative review explores the potential role of obesity in breast cancer progression and treatment resistance with inflammation as an underlying mechanism.

Towards a Model-Based Dose Recommendation for Doxorubicin in Children

Following the publication of our paper regarding a population-based model of doxorubicin pharmacokinetics in children in Clinical Pharmacokinetics last year (Voller et al. 54:1139-1149, 2015), we have received many inquiries on the practical clinical consequences of this model; however, a population-based model is only one of the aspects to be taken into account when developing dosing algorithms. In addition, any new method of dose calculation would need clinical validation and, subsequently, a new clinical trial. However, such a trial, especially with regard to burden to the children involved, requires optimal preparation and the selection of the best hypotheses. The European Paediatric Oncology Off-Patent Medicines Consortium (EPOC), represented by the authors, would therefore like to initiate an interdisciplinary discussion on the clinical and pharmacological goals for dose calculation. This current opinion summarizes the existing knowledge on the pharmacokinetics and pharmacodynamics of doxorubicin. Our aim was to define the clinical needs as precisely as possible, with the intention of stimulating discussion between the clinical pediatric oncologist and the pediatric pharmacologist. By doing so, we hope to define surrogates for best practice of a common doxorubicin dose in children. The intent is for a trial to validate a rational dose calculation rule, leading to a regulatory process and subsequent labeling.

Adipocytes Sequester and Metabolize the Chemotherapeutic Daunorubicin

Obesity is associated with poorer outcome for many cancers. Previously, we observed that adipocytes protect acute lymphoblastic leukemia (ALL) cells from the anthracycline, daunorubicin. In this study, it is determined whether adipocytes clear daunorubicin from the tumor microenvironment (TME). Intracellular daunorubicin concentrations were evaluated using fluorescence. Daunorubicin and its largely inactive metabolite, daunorubicinol, were analytically measured in media, cells, and tissues using liquid chromatography/mass spectrometry (LC/MS). Expression of daunorubicin-metabolizing enzymes, aldo-keto reductases (AKR1A1, AKR1B1, AKR1C1, AKR1C2, AKR1C3, and AKR7A2) and carbonyl reductases (CBR1, CBR3), in human adipose tissue, were queried using public databases and directly measured by quantitative PCR (qPCR) and immunoblot. Adipose tissue AKR activity was measured by colorimetric assay. Adipocytes absorbed and efficiently metabolized daunorubicin to daunorubicinol, reducing its antileukemia effect in the local microenvironment. Murine studies confirmed adipose tissue conversion of daunorubicin to daunorubicinol in vivo Adipocytes expressed high levels of AKR and CBR isoenzymes that deactivate anthracyclines. Indeed, adipocyte protein levels of AKR1C1, AKR1C2, and AKR1C3 are higher than all other human noncancerous cell types. To our knowledge, this is the first demonstration that adipocytes metabolize and inactivate a therapeutic drug. Adipocyte-mediated daunorubicin metabolism reduces active drug concentration in the TME. These results could be clinically important for adipocyte-rich cancer microenvironments such as omentum, breast, and marrow. As AKR and CBR enzymes metabolize several drugs, and can be expressed at higher levels in obese individuals, this proof-of-principle finding has important implications across many diseases.Implications: Adipocyte absorption and metabolism of chemotherapies can reduce cytotoxicity in cancer microenvironments, potentially contributing to poorer survival outcomes. Mol Cancer Res; 15(12); 1704-13. ©2017 AACR.

Population pharmacokinetics of doxorubicin and doxorubicinol in patients diagnosed with non-Hodgkin's lymphoma

AIMS

The aims of the study were: (i) to characterize the pharmacokinetics (PK) of doxorubicin (DOX) and doxorubicinol (DOXol) in patients diagnosed with non-Hodgkin's lymphoma (NHL) using a population approach; (ii) to evaluate the influence of various covariates on the PK of DOX; and (iii) to evaluate the role of DOX and DOXol exposure in haematological toxicity.

METHODS

Population PK modelling (using NONMEM) was performed using DOX and DOXol plasma concentration-time data from 45 NHL patients treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone). The influence of drug exposure on haematological toxicity was analysed using the Mann-Whitney-Wilcoxon test.

RESULTS

A five-compartment model, three for DOX and two for DOXol, with first-order distribution and elimination for both entities best described the data. Population estimates for parent drug (CL) and metabolite (CL_m ) clearance were 62 l h^-1 and 27 l h^-1 , respectively. The fraction metabolized to DOXol (F_m ) was estimated at 0.22. While bilirubin and aspartate aminotransferase showed an influence on the CL and CL_m , the objective function value decrease was not statistically significant. A trend towards an association between the total area under the concentration-time curve (AUC_total ), the area under the concentration-time curve for DOX (AUC) plus the area under the concentration-time curve for DOXol (AUC_m ), and the neutropenia grade (P = 0.068) and the neutrophil counts (P = 0.089) was observed, according to an exponential relationship.

CONCLUSIONS

The PK of DOX and DOXol were well characterized by the model developed, which could be used as a helpful tool to optimize the dosage of this drug. The results suggest that the main active metabolite of DOX, DOXol, is involved in the haematological toxicity of the parent drug.

Pharmacokinetic-pharmacodynamic modelling of acute N-terminal pro B-type natriuretic peptide after doxorubicin infusion in breast cancer

AIMS

The aim of the present study was to develop a pharmacokinetic-pharmacodynamic (PK-PD) model to characterize the relationship between plasma doxorubicin and N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations within 48 h of doxorubicin treatment.

METHODS

The study enrolled 17 female patients with stages 1-3 breast cancer and receiving adjuvant doxorubicin (60 mg m(-2) ) and cyclophosphamide (600 mg m(-2) ) every 14 days for four cycles. In two consecutive cycles, plasma concentrations of doxorubicin, doxorubicinol, troponin and NT-proBNP were collected before infusion, and up to 48 h after the end of doxorubicin infusion. Nonlinear mixed-effects modelling was used to describe the PK-PD relationship of doxorubicin and NT-proBNP.

RESULTS

A three-compartment parent drug with a one-compartment metabolite model best described the PK of doxorubicin and doxorubicinol. Troponin concentrations remained similar to baseline. An indirect PD model with transit compartments best described the relationship of doxorubicin exposure and acute NT-proBNP response. Estimated PD parameters were associated with large between-subject variability (total assay variability 38.8-73.9%). Patient clinical factors, including the use of enalapril, were not observed to be significantly associated with doxorubicin PK or NT-proBNP PD variability.

CONCLUSION

The relationship between doxorubicin concentration and the acute NT-proBNP response was successfully described with a population PK-PD model. This model will serve as a valuable framework for future studies to identify clinical factors associated with the acute response to doxorubicin. Future studies are warranted to examine the relationship between this acute response and subsequent heart failure. Should such a relationship be established, this model could provide useful information on patients' susceptibility to doxorubicin-induced long-term cardiotoxicity.

Association of body mass index and survival in pediatric leukemia: a meta-analysis

BACKGROUND

Obesity is a worldwide epidemic in children and adolescents. Adult cohort studies have reported an association between higher body mass index (BMI) and increased leukemia-related mortality; whether a similar effect exists in childhood leukemia remains controversial.

OBJECTIVE

We conducted a meta-analysis to determine whether a higher BMI at diagnosis of pediatric acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML) is associated with worse event-free survival (EFS), overall survival (OS), and cumulative incidence of relapse (CIR).

DESIGN

We searched 4 electronic databases from inception through March 2015 without language restriction and included studies in pediatric ALL or AML (0-21 y of age) reporting BMI as a predictor of survival or relapse. Higher BMI, defined as obese (≥95%) or overweight/obese (≥85%), was compared with lower BMI [nonoverweight/obese (<85%)]. Summary risk estimates for EFS, OS, and CIR (ALL only) were calculated with random- or fixed-effects models according to tests for between-study heterogeneity.

RESULTS

Of 4690 reports identified, 107 full-text articles were evaluated, with 2 additional articles identified via review of citations; 11 articles were eligible for inclusion in this meta-analysis. In ALL, we observed poorer EFS in children with a higher BMI (RR: 1.35; 95% CI: 1.20, 1.51) than in those at a lower BMI. A higher BMI was associated with significantly increased mortality (RR: 1.31; 95% CI: 1.09, 1.58) and a statistically nonsignificant trend toward greater risk of relapse (RR: 1.17; 95% CI: 0.99, 1.38) compared with a lower BMI. In AML, a higher BMI was significantly associated with poorer EFS and OS (RR: 1.36; 95% CI: 1.16, 1.60 and RR: 1.56; 95% CI: 1.32, 1.86, respectively) than was a lower BMI.

CONCLUSION

Higher BMI at diagnosis is associated with poorer survival in children with pediatric ALL or AML.

Testosterone Antagonizes Doxorubicin-Induced Senescence of Cardiomyocytes

Background

Chronic cardiotoxicity is less common in male than in female patients receiving doxorubicin and other anthracyclines at puberty and adolescence. We hypothesized that this sex difference might be secondary to distinct activities of sex hormones on cardiomyocyte senescence, which is thought to be central to the development of long‐term anthracycline cardiomyopathy.

Methods and Results

H9c2 cells and neonatal mouse cardiomyocytes were exposed to doxorubicin with or without prior incubation with testosterone or 17β‐estradiol, the main androgen and estrogen, respectively. Testosterone, but not 17β‐estradiol, counteracted doxorubicin‐elicited senescence. Downregulation of telomere binding factor 2, which has been pinpointed previously as being pivotal to doxorubicin‐induced senescence, was also prevented by testosterone, as were p53 phosphorylation and accumulation. Pretreatment with the androgen receptor antagonist flutamide, the phosphatidylinositol 3 kinase inhibitor LY294002, and the nitric oxide synthase inhibitor L‐NG‐nitroarginine methyl ester abrogated the reduction in senescence and the normalization of telomere binding factor 2 levels attained by testosterone. Consistently, testosterone enhanced the phosphorylation of AKT and nitric oxide synthase 3. In H9c2 cells, doxorubicin‐stimulated senescence was still observed up to 21 days after treatment and increased further when cells were rechallenged with doxorubicin 14 days after the first exposure to mimic the schedule of anthracycline‐containing chemotherapy. Remarkably, these effects were also inhibited by testosterone.

Conclusions

Testosterone protects cardiomyocytes against senescence caused by doxorubicin at least in part by modulating telomere binding factor 2 via a pathway involving the androgen receptor, phosphatidylinositol 3 kinase, AKT, and nitric oxide synthase 3. This is a potential mechanism by which pubescent and adolescent boys are less prone to chronic anthracycline cardiotoxicity than girls.

Impact of gender on efficacy and acute toxicity of alkylating agent -based chemotherapy in Ewing sarcoma: secondary analysis of the Euro-Ewing99-R1 trial

BACKGROUND

Based on the randomised Euro-EWING99-R1 trial, vincristine, adriamycin, cyclophosphamide (VAC) may be able to replace vincristine, adriamycin, ifosfamide (VAI) in the treatment of standard-risk Ewing sarcoma. However some heterogeneity of treatment effect by gender was observed. The current exploratory study aimed at investigating the influence of gender on treatment efficacy and acute toxicity.

PATIENTS AND METHODS

Impact of gender on event-free survival (EFS), acute toxicity by course, switches between treatment arms and cumulative dose of alkylating agents was evaluated in multivariable models adjusted for age including terms to test for heterogeneity of treatment effect by gender. The analysis of the EFS was performed on the intention-to-treat population.

RESULTS

EFS did not significantly differ between the 509 males and 347 females (p=0.33), but an interaction in terms of efficacy was suspected between treatment and gender (p=0.058): VAC was associated with poorer EFS than VAI in males, hazard ratio (HR) (VAC/VAI)=1.37 [95% confidence interval (CI), 0.98-1.90], contrasting with HR=0.81 [95%CI, 0.53-1.24] in females. Severe toxicity was more frequent in females, whatever the toxicity type. Thirty patients switched from VAI to VAC (9/251 males, 4%, and 21/174 females, 12%) mostly due to renal toxicity, and three from VAC to VAI (2/258 males, 0.8%, and 1/173 females, 0.6%). A reduction of alkylating agent cumulative dose >20% was more frequent in females (15% versus 9%, p=0.005), with no major difference between VAC and VAI (10% versus 13%, p=0.15).

CONCLUSION

Differences of acute toxicity rate and cumulative doses of alkylating agents could not explain the marginal interaction observed in the Euro-EWING99-R1 trial data. Effects of gender-dependent polymorphism/activity of metabolic enzymes (e.g. known for CYP2B6) of ifosfamide versus cyclophosphamide should be explored. External data are required to further evaluate whether there is heterogeneity of alkylating agent effect by gender.

TRIAL NUMBERS

NCT00987636 and EudraCT 2008-003658-13.

Pharmacokinetic and pharmacodynamic study of tariquidar (XR9576), a P-glycoprotein inhibitor, in combination with doxorubicin, vinorelbine, or docetaxel in children and adolescents with refractory solid tumors

PURPOSE

P-glycoprotein (Pgp), an ATP-dependent transport protein, confers multidrug resistance in cancer cells. Tariquidar binds and inhibits Pgp. To assess the toxicity, pharmacokinetics (PK), and pharmacodynamics of tariquidar, we conducted a phase I trial of tariquidar in combination with doxorubicin, docetaxel, or vinorelbine in children and adolescents with recurrent or refractory solid tumors.

METHODS

Patients less than 19 years of age with refractory or recurrent solid tumors were eligible. Tariquidar (1, 1.5, or 2 mg/kg) was administered alone and in combination with doxorubicin, docetaxel, or vinorelbine. PK of tariquidar and cytotoxic drugs was performed. Pgp function was assessed by a rhodamine efflux assay and (99m)Tc-sestamibi scintigraphy. Tumor Pgp expression was assessed by immunohistochemistry. Response was assessed using Response Evaluation Criteria in Solid Tumors.

RESULTS

Twenty-nine subjects were enrolled. No tariquidar-related dose-limiting toxicity (DLT) was observed. DLT related to cytotoxic drugs occurred in 12 % of subjects receiving tariquidar 2 mg/kg. When administered in combination with tariquidar, the clearance of docetaxel and vinorelbine was reduced compared to prior studies. Inhibition of rhodamine efflux was dose dependent. After tariquidar administration, (99m)Tc-sestamibi accumulation in tumor increased by 22 %. Objective responses (1 complete, 2 partial) were observed. There was no association between tumor Pgp expression and response.

CONCLUSION

A tolerable and biologically active dose of tariquidar was established in children and adolescents. This trial demonstrates that modulators of resistance can be evaluated in combination with chemotherapy, and pharmacokinetic and pharmacodynamic endpoints can be useful in determination of recommended dose in children and adolescents.

Impact of obesity on accumulation of the toxic irinotecan metabolite, SN-38, in mice

AIM

Our aim is to investigate the impact of high fat diet-induced obesity on plasma concentrations of the toxic irinotecan metabolite, SN-38, in mice.

MAIN METHODS

Diet-induced obese (DIO, 60% kcal fed) and lean mice (10% kcal fed) were treated orally with a single dose of 10mg/kg irinotecan to determine pharmacokinetic (PK) parameters. Feces and livers were collected for quantification of irinotecan and its metabolites (SN-38 & SN-38G). SN-38G formation by Ugt1a1 enzyme was analyzed in liver S9 fractions. Expression of the pro-inflammatory cytokine, TNF-α was determined in liver and plasma. Hepatic β-glucuronidase and carboxylesterase enzymes (CES) were also determined.

KEY FINDINGS

AUC0-8 and Cmax of SN-38 increased by 2-fold in DIO mice compared to their lean controls. This was accompanied by a~2-fold reduction in AUC0-8 and Cmax of SN-38G in DIO mice. There were no differences in the PK parameters of irinotecan in DIO or lean mice. Conversion of SN-38 to SN-38G by Ugt1a1 enzyme was reduced by ~2-fold in liver S9 fractions in DIO mice. Furthermore, in DIO mice, β-glucuronidase activity increased by 2-fold, whereas there was no change in CES activity. TNF-α mRNA expression was 3 fold higher in DIO mice.

SIGNIFICANCE

Our study demonstrates that reduced hepatic Ugt1a activity during obesity likely contributes to reduced glucuronidation, and results in higher levels of the toxic metabolite, SN-38. Thus, irinotecan dosage should be closely monitored for effective and safe chemotherapy in obese cancer patients who are at a higher risk of developing liver toxicity.

Drug Dosing and Pharmacokinetics in Children With Obesity: A Systematic Review

IMPORTANCE

Obesity affects nearly one-sixth of US children and results in alterations to body composition and physiology that can affect drug disposition, possibly leading to therapeutic failure or toxic side effects. The depth of available literature regarding obesity's effect on drug safety, pharmacokinetics, and dosing in obese children is unknown.

OBJECTIVE

To perform a systematic literature review describing the current evidence of the effect of obesity on drug disposition in children.

EVIDENCE REVIEW

We searched the MEDLINE, Cochrane, and EMBASE databases (January 1, 1970-December 31, 2012) and included studies if they contained data on drug clearance, volume of distribution, or drug concentration in obese children (aged ≤18 years). We compared exposure and weight-normalized volume of distribution and clearance between obese and nonobese children. We explored the association between drug physicochemical properties and clearance and volume of distribution.

FINDINGS

Twenty studies met the inclusion criteria and contained pharmacokinetic data for 21 drugs. The median number of obese children studied per drug was 10 (range, 1-112) and ages ranged from newborn to 29 years (1 study described pharmacokinetics in children and adults together). Dosing schema varied and were either a fixed dose (6 [29%]) or based on body weight (10 [48%]) and body surface area (4 [19%]). Clinically significant pharmacokinetic alterations were observed in obese children for 65% (11 of 17) of the studied drugs. Pharmacokinetic alterations resulted in substantial differences in exposure between obese and nonobese children for 38% (5 of 13) of the drugs. We found no association between drug lipophilicity or Biopharmaceutical Drug Disposition Classification System class and changes in volume of distribution or clearance due to obesity.

CONCLUSIONS AND RELEVANCE

Consensus is lacking on the most appropriate weight-based dosing strategy for obese children. Prospective pharmacokinetic trials in obese children are needed to ensure therapeutic efficacy and enhance drug safety.

The challenge of obesity in paediatric leukaemia treatment: it is not just size that matters

In the last two decades, tremendous advances have been made in the treatment of acute lymphocytic leukaemia (ALL) in children with 5 year 'cure' rates in excess of 90%. The maintenance of remission is due, in part, to individualisation of therapy which must consider age, body size, genetic constitution and the impact of disease on drug disposition and action. This review, focused on treatment of ALL and one of the therapeutic mainstays, 6-mercaptopurine, illustrates the importance of obesity as a modulating factor in dose individualisation.

Pharmacokinetics and pharmacogenomics of daunorubicin in children: a report from the Children's Oncology Group

PURPOSE

We explored the impact of obesity, body composition, and genetic polymorphisms on the pharmacokinetics (PK) of daunorubicin in children with cancer.

PATIENTS AND METHODS

Patients ≤21 years receiving daunorubicin as an infusion of any duration <24 h for any type of cancer were eligible. Plasma drug concentrations were measured by high-performance liquid chromatography. Body composition was measured by dual-energy X-ray absorptiometry. Obesity was defined as a BMI >95% for age or as body fat >30%. NONMEM was used to perform PK model fitting. The Affymetrix DMET chip was used for genotyping. The impact of genetic polymorphisms was investigated using SNP/haplotype association analysis with estimated individual PK parameters.

RESULTS

A total of 107 subjects were enrolled, 98 patients had PK sampling, and 50 patients underwent DNA analysis. Population estimates for daunorubicin clearance and volume of distribution were 116 L/m(2)/h ± 14% and 68.1 L/m(2) ± 24%, respectively. Apparent daunorubicinol clearance and volume of distribution were 26.8 L/m(2)/h ± 5.6% and 232 L/m(2) ± 10%, respectively. No effect of body composition or obesity was observed on PK. Forty-four genes with variant haplotypes were tested for association with PK. FMO3-H1/H3 genotype was associated with lower daunorubicin clearance than FMO3-H1/H1, p = 0.00829. GSTP1*B/*B genotype was also associated with lower daunorubicin clearance compared to GSTP1*A/*A, p = 0.0347. However, neither of these associations was significant after adjusting for multiple testing by either Bonferroni or false discovery rate correction.

CONCLUSIONS

We did not detect an effect of body composition or obesity on daunorubicin PK. We found suggestive associations between FMO3 and GSTP1 haplotypes with daunorubicin PK that could potentially affect efficacy and toxicity.