Oxidative stress and executive function in children receiving chemotherapy for acute lymphoblastic leukemia

Impaired neurocognitive functioning 3 months following diagnosis of high-risk acute lymphoblastic leukemia: A report from the Children's Oncology Group

PURPOSE

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer diagnosis. Cognitive late effects develop in 20%-40% of ALL survivors, but the course of declines is unclear. The aim of this paper is to characterize cognitive functioning, and its association with patient-reported outcomes, early in treatment.

PATIENTS AND METHODS

A total of 483 children with high-risk ALL, aged 6-12 years at diagnosis, consented to the neurocognitive study embedded in a prospective therapeutic trial, Children's Oncology Group (COG) AALL1131. A computerized neurocognitive battery (Cogstate) was administered 3 months post diagnosis assessing reaction time, visual attention, working memory, visual learning, and executive functioning. Parent-reported executive functioning and patient-reported physical symptoms were also collected.

RESULTS

Data from 390 participants (mean age at diagnosis = 9.2 years, 55.4% male) were obtained. Relatively few patients reported pain (16.0%) or nausea (22.6%), but a majority (68.5%) reported feeling at least some fatigue at testing. Mean Cogstate Z-scores were within normal limits across tasks; however, rates of impairment (Z-scores ≤ -1.5) for reaction time, working memory, visual learning, and visual attention were all higher than expected compared to the standardization sample. Patients reporting fatigue were significantly more likely to have impaired reaction time and visual attention compared to those reporting no fatigue.

CONCLUSION

Findings support feasibility of computerized cognitive assessments and suggest higher-than-expected rates of impaired cognitive performance early during treatment for pediatric ALL, notably within 3 months of diagnosis, suggesting intervention efforts may be indicated. These results also highlight acute factors that may impact reliability of "baseline" assessments conducted soon after diagnosis.

Processing efficiency in pediatric cancer survivors: A review and operationalization for outcomes research and clinical utility

OBJECTIVE

Childhood cancer and cancer-related treatments disrupt brain development and maturation, placing survivors at risk for cognitive late effects. Given that assessment tools vary widely across researchers and clinicians, it has been daunting to identify distinct patterns in outcomes across diverse cancer types and to implement systematic neurocognitive screening tools. This review aims to operationalize processing efficiency skill impairment-or inefficient neural processing as measured by working memory and processing speed abilities-as a worthwhile avenue for continued study within the context of childhood cancer.

METHODS

A comprehensive literature review was conducted to examine the existing research on cognitive late effects and biopsychosocial risk factors in order to conceptualize processing efficiency skill trends in childhood cancer survivors.

RESULTS

While a frequently reported pattern of neurobiological (white matter) and cognitive (working memory and processing speed) disruption is consistent with processing efficiency skill impairment, these weaknesses have not yet been fully operationalized in this population. We offer a theoretical model that highlights the impacts of a host of biological and environmental factors on the underlying neurobiological substrates of cancer survivors that precede and may even predict long-term cognitive outcomes and functional abilities following treatment.

CONCLUSION

The unified construct of processing efficiency may be useful in assessing and communicating neurocognitive skills in both outcomes research and clinical practice. Deficits in processing efficiency may serve as a possible indicator of cognitive late effects and functional outcomes due to the unique relationship between processing efficiency skills and neurobiological disruption following cancer treatment. Continued research along these lines is crucial for advancing childhood cancer outcomes research and improving quality of life for survivors.

Cannabinoid drugs against chemotherapy-induced adverse effects: focus on nausea/vomiting, peripheral neuropathy and chemofog in animal models

Although new drugs are being developed for cancer treatment, classical chemotherapeutic agents are still front-line therapies, despite their frequent association with severe side effects that can hamper their use. Cannabinoids may prevent or palliate some of these side effects. The aim of the present study is to review the basic research which has been conducted evaluating the effects of cannabinoid drugs in the treatment of three important side effects induced by classical chemotherapeutic agents: nausea and vomiting, neuropathic pain and cognitive impairment. Several published studies have demonstrated that cannabinoids are useful in preventing and reducing the nausea, vomits and neuropathy induced by different chemotherapy regimens, though other side effects can occur, such as a reduction of gastrointestinal motility, along with psychotropic effects when using centrally-acting cannabinoids. Thus, peripherally-acting cannabinoids and new pharmacological options are being investigated, such as allosteric or biased agonists. Additionally, due to the increase in the survival of cancer patients, there are emerging data that demonstrate an important cognitive deterioration due to chemotherapy, and because the cannabinoid drugs have a neuroprotective effect, they could be useful in preventing chemotherapy-induced cognitive impairment (as demonstrated through studies in other neurological disorders), but this has not yet been tested. Thus, although cannabinoids seem a promising therapeutic approach in the treatment of different side effects induced by chemotherapeutic agents, future research will be necessary to find pharmacological options with a safer profile. Moreover, a new line of research awaits to be opened to elucidate their possible usefulness in preventing cognitive impairment.

Biomarkers and Cognitive Function in Children and Adolescents During Maintenance Therapy for Leukemia

OBJECTIVES

To explore the relationship between biomarkers of oxidative stress and inflmmation in cerebrospinal fluid (CSF) and cognitive function in children receiving maintenance therapy for acute lymphocytic leukemia (ALL).

SAMPLE & SETTING

30 participants aged 4-17 years receiving ALL maintenance therapy at two pediatric cancer centers in the United States.

METHODS & VARIABLES

F2-isoprostane (F2-ISoP) and interleukin-8 (IL-8) were evaluated in CSF samples, and cognitive function measures were completed during the first and last cycles of ALL maintenance. The Flanker Inhibitory Control and Attention Test (Flanker) and Dimensional Change Card Sort were completed during the last cycle.

RESULTS

During maintenance therapy, IL-8 decreased, and parent reports of children's cognitive function improved. Higher IL-8 was associated with better parent reports of children's cognitive function at each timepoint. Higher F2-ISoP levels were associated with lower Flanker scores.

IMPLICATIONS FOR NURSING

F2-ISoP may be a useful biomarker in evaluating cognitive dysfunction in children with ALL and merits further investigation.

Elevated Oxidative Stress and DNA Damage in Cortical Neurons of Chemotherapy Patients

The unintended neurologic sequelae of chemotherapy contribute to significant patient morbidity. Chemotherapy-related cognitive impairment (CRCI) is observed in up to 80% of cancer patients treated with chemotherapy and involves multiple cognitive domains including executive functioning. The pathophysiology underlying CRCI and the neurotoxicity of chemotherapy is incompletely understood, but oxidative stress and DNA damage are highly plausible mechanisms based on preclinical data. Unfortunately, validating pathways relevant to CRCI in humans is limited by an absence of relevant neuropathologic studies of patient brain tissue. In the present study, we stained sections of frontal lobe autopsy tissue from cancer patients treated with chemotherapy (n = 15), cancer patients not treated with chemotherapy (n = 10), and patients without history of cancer (n = 10) for markers of oxidative stress (nitrotyrosine, 4-hydroxynonenal) and DNA damage (pH2AX, pATM). Cancer patients treated with chemotherapy had increased staining for markers of oxidative stress and DNA damage in frontal lobe cortical neurons compared to controls. We detected no statistically significant difference in oxidative stress and DNA damage by the duration between last administration of chemotherapy and death. The study highlights the potential relevance of oxidative stress and DNA damage in the pathophysiology of CRCI and the neurotoxicity of chemotherapy.

The Role of Oxidative Stress and Inflammation in Cardiometabolic Health of Children During Cancer Treatment and Potential Impact of Key Nutrients

Significance: The 5-year survival rate of childhood cancers is now reaching 84%. However, treatments cause numerous acute and long-term side effects. These include cardiometabolic complications, namely hypertension, dyslipidemia, hyperglycemia, insulin resistance, and increased fat mass. Recent Advances: Many antineoplastic treatments can induce oxidative stress (OxS) and trigger an inflammatory response, which may cause acute and chronic side effects. Critical Issues: Clinical studies have reported a state of heightened OxS and inflammation during cancer treatment in children as the result of treatment cytotoxic action on both cancerous and noncancerous cells. Higher levels of OxS and inflammation are associated with treatment side effects and with the development of cardiometabolic complications. Key nutrients (omega-3 polyunsaturated fatty acids, dietary antioxidants, probiotics, and prebiotics) have the potential to modulate inflammatory and oxidative responses and, therefore, could be considered in the search for adverse complication prevention means as long as antineoplastic treatment efficiency is maintained. Future Directions: There is a need to better understand the relationship between cardiometabolic complications, OxS, inflammation and diet during pediatric cancer treatment, which represents the ultimate goal of this review. Antioxid. Redox Signal. 35, 293-318.

Oxidative Stress in Cerebrospinal Fluid During Treatment in Childhood Acute Lymphoblastic Leukemia

Introduction

Central nervous system (CNS) treatment using intrathecal chemotherapy and cranial radiation to enable long-term disease-free survival from childhood acute lymphoblastic leukemia (ALL) comes at the cost of neurotoxic side effects and long-term sequelae. We investigated oxidative stress as a possible mechanism of chemotherapy-induced neurotoxicity in children with ALL.

Materials and methods

In this case-control study, we estimated the cerebrospinal fluid (CSF) levels of 8-hydroxy-deoxyguanosine (8-OH-dG), a DNA damage product, in children with B-cell ALL and control children. CSF samples were collected at diagnosis, at end of Induction 1, Induction 2, and Induction 2A - consolidation phase. CSF 8-OH-dG levels were compared in children with and without neurotoxicity.

Results

Children with ALL (n=23) at diagnosis had significantly higher median (interquartile range, IQR) CSF 8-OH-dG levels (ng/mL) compared to controls (n=19) [1.97 (1.59-2.56) Vs 0.65 (0.59-0.82), P<0.001]. CSF 8-OH-dG levels at the end of four weeks, eight weeks, and 16 weeks of chemotherapy were [3.96 (2.85-5.44) ng/mL], 1.00 (0.89-1.09), and 3.73 (2.80-4.39) ng/mL, respectively. Out of 23 children with ALL, 12 developed neurotoxicity; the CSF levels of 8-OH-dG in them were only marginally higher compared to those who did not develop neurotoxicity. The CSF 8-OH-dG levels did not show a significant correlation with the number of doses of methotrexate or vincristine received.

Conclusion

Chemotherapy increases the CNS oxidative stress as measured by CSF 8-OH-dG levels, with the levels being proportional to the intensity of chemotherapy. Children with neurotoxicity had only marginally higher CSF 8-OH-dG levels as compared to children without neurotoxicity.

Methylene tetrahydrofolate reductase A1298C polymorphisms influence the adult sequelae of chemotherapy in childhood-leukemia survivors

This retrospective correlation study investigated the putative link between methylene tetrahydrofolate reductase (MTHFR) A1298C mutations and chemotherapy-related brain function changes in adult childhood-leukemia survivors. To this end, we determined the relationship between the particular MTHFR1298 genotype (AA, AC or CC) of 31 adult childhood-leukemia survivors, and (1) their CSF Tau and phosphorylated Tau (pTau) levels at the time of treatment, (2) their adult performance intelligence quotient (PIQ), and (3) their regional brain connectivity using diffusion magnetic resonance imaging (dMRI) and resting-state functional MRI (rsfMRI). We confirmed that neuropathology markers Tau and pTau significantly increased in CSF of children after intrathecal methotrexate administration. Highest concentrations of these toxicity markers were found during the induction phase of the therapy. Moreover, CSF concentrations of Tau and pTau during treatment were influenced by the children’s particular MTHFR1298 genotype. CSF Tau (but not pTau) levels significantly dropped after folinic acid supplementation. At adult age (on average 13.1 years since the end of their treatment), their particular MTHFR1298 genotype (AA, AC or CC) influenced the changes in PIQ and cortical connectivity that we found to be related to their childhood exposure to chemotherapeutics. In summary, we suggest that homozygous MTHFR1298CC individuals are more vulnerable to the adult sequelae of antifolate chemotherapy.

Age- and Intravenous Methotrexate-Associated Leukoencephalopathy and Its Neurological Impact in Pediatric Patients with Lymphoblastic Leukemia

Simple Summary

In this study, we investigated standardized post-chemotherapy magnetic resonance (MR) scans for leukoencephalopathy and patient- and treatment-related risk factors in childhood leukemia patients. As prevalence numbers are limited, our study provides the required estimations for this population. Furthermore, we demonstrate that younger patients might be more at-risk for development of leukoencephalopathy (LE), and that a higher intravenous methotrexate (IV-MTX) dose has a cumulative toxic effect, while the number of intrathecal administrations was not significantly associated with the extent of LE. This can suggest we should modify chemotherapeutic treatment regimens by decreasing the number of IV-MTX applications, with special attention for younger patients.

Abstract

Methotrexate (MTX) is associated with leukoencephalopathy (LE) in children treated for lymphoblastic leukemia/lymphoma (ALL/LBL). However, large-scale studies with systematic MR acquisition and quantitative volumetric lesion information remain limited. Hence, the prevalence of lesion burdens and the potential risk factors of LE in this population are still inconclusive. FLAIR-MRI scans were acquired at the end of treatment in children who were treated for ALL/LBL, which were quantitatively analyzed for LE. Voxels were assigned to the lesion segmentation if indicated by two raters. Logistic and linear regression models were used to test whether lesion presence and size were predicted by risk factors such as age at diagnosis, gender, intrathecal (IT-) or intravenous (IV-)MTX dose, CNS invasion, and acute neurological events. Patients with a pre-existing neurological condition or low-quality MR scan were excluded from the analyses. Of the 129 patients, ten (8%) suffered from CNS invasion. Chemotherapy-associated neurological events were observed in 13 patients (10%) during therapy, and 68 patients (53%) showed LE post-treatment. LE was more frequent in cases of lower age and higher cumulative IV-MTX doses, while the extent of LE and neurological symptoms were associated only with IV-MTX doses. Neurological events were not significantly associated with LE, even though symptomatic patients demonstrated a higher ratio of LE (n = 9/13) than asymptomatic patients (n = 59/116). This study suggests leukoencephalopathy frequently occurs in both symptomatic and asymptomatic leukemia patients. Younger children and patients treated with higher cumulative IV-MTX doses might need more regular screening for early detection and follow-up of associated sequelae.

Cognitive function of children and adolescent survivors of acute lymphoblastic leukemia: A meta-analysis

Pediatric cancer and its treatment may have an impact on the neurocognitive functions of childhood cancer survivors (CCS). The aim of the present meta-analysis was to compare the intelligence quotient (IQ) scores between CCS of acute lymphoblastic leukemia (ALL) and controls. A comprehensive electronic search identified original research articles that reported scores of the Wechsler Intelligence Scale (WISC; WISC-III, WISC-IV and WISC-R) for children and adolescents, aged 6-16 years at evaluation, survivors of ALL and healthy controls. The included CCS had completed anticancer treatment and were in remission at the time of assessment. A total of 16 studies were included in the meta-analysis, out of 128 extracted studies, and involved a total of 1,676 children and adolescents: 991 CCS (ALL) and 685 healthy controls. Among the studies, a random effects model revealed a moderate estimate of effect size [standardized mean difference (SMD), -0.78; 95% CI, -1.05 to -0.50], indicating that the WISC scores for total IQ were significantly lower in the CCS than in the controls. The mean total IQ range was 85.2-107.2 in the CCS and 88.4-114.1 in the controls. The difference in the mean total IQ between controls and CCS ranged from -13.8 to 20.6. As regards the WISC scores for verbal IQ, 11 studies were included. A random effects model revealed a moderate estimate of effect size (SMD, -0.71; 95% CI, -1.05 to -0.38), indicating that the WISC scores for verbal IQ were significantly lower in the CCS than in the controls. Among the 9 studies that had available data for performance IQ scores, a fixed effect model revealed a moderate estimate of effect size (SMD, -0.80; 95% CI, -1.09 to -0.52), indicating that the WISC scores for performance IQ were significantly lower in the CCS than in the controls. As the survival rates of children and adolescents with ALL are steadily increasing, regular, lifelong follow-up for neurocognitive late effects is imperative in order to improve their education and employment prospects and overall, their quality of life.

Cerebrospinal Fluid Biomarkers in Childhood Leukemias

Involvement of the central nervous system (CNS) in childhood leukemias remains a major cause of treatment failures. Analysis of the cerebrospinal fluid constitutes the most important diagnostic pillar in the detection of CNS leukemia and relies primarily on cytological and flow-cytometry studies. With increasing survival rates, it has become clear that treatments for pediatric leukemias pose a toll on the developing brain, as they may cause acute toxicities and persistent neurocognitive deficits. Preclinical research has demonstrated that established and newer therapies can injure and even destroy neuronal and glial cells in the brain. Both passive and active cell death forms can result from DNA damage, oxidative stress, cytokine release, and acceleration of cell aging. In addition, chemotherapy agents may impair neurogenesis as well as the function, formation, and plasticity of synapses. Clinical studies show that neurocognitive toxicity of chemotherapy is greatest in younger children. This raises concerns that, in addition to injury, chemotherapy may also disrupt crucial developmental events resulting in impairment of the formation and efficiency of neuronal networks. This review presents an overview of studies demonstrating that cerebrospinal fluid biomarkers can be utilized in tracing both CNS disease and neurotoxicity of administered treatments in childhood leukemias.

Animal models of chemotherapy-induced cognitive decline in preclinical drug development

RATIONALE

Chemotherapy-induced cognitive impairment (CICI), chemobrain, and chemofog are the common terms for mental dysfunction in a cancer patient/survivor under the influence of chemotherapeutics. CICI is manifested as short/long term memory problems and delayed mental processing, which interferes with a person's day-to-day activities. Understanding CICI mechanisms help in developing therapeutic interventions that may alleviate the disease condition. Animal models facilitate critical evaluation to elucidate the underlying mechanisms and form an integral part of verifying different treatment hypotheses and strategies.

OBJECTIVES

A methodical evaluation of scientific literature is required to understand cognitive changes associated with the use of chemotherapeutic agents in different preclinical studies. This review mainly emphasizes animal models developed with various chemotherapeutic agents individually and in combination, with their proposed mechanisms contributing to the cognitive dysfunction. This review also points toward the analysis of chemobrain in healthy animals to understand the mechanism of interventions in absence of tumor and in tumor-bearing animals to mimic human cancer conditions to screen potential drug candidates against chemobrain.

RESULTS

Substantial memory deficit as a result of commonly used chemotherapeutic agents was evidenced in healthy and tumor-bearing animals. Spatial and episodic cognitive impairments, alterations in neurotrophins, oxidative and inflammatory markers, and changes in long-term potentiation were commonly observed changes in different animal models irrespective of the chemotherapeutic agent.

CONCLUSION

Dyscognition exists as one of the serious side effects of cancer chemotherapy. Due to differing mechanisms of chemotherapeutic agents with differing tendencies to alter behavioral and biochemical parameters, chemotherapy may present a significant risk in resulting memory impairments in healthy as well as tumor-bearing animals.

Connectivity of the Cerebello-Thalamo-Cortical Pathway in Survivors of Childhood Leukemia Treated With Chemotherapy Only

IMPORTANCE

Treatment with contemporary chemotherapy-only protocols is associated with risk for neurocognitive impairment among survivors of childhood acute lymphoblastic leukemia (ALL).

OBJECTIVE

To determine whether concurrent use of methotrexate and glucocorticoids is associated with interference with the antioxidant system of the brain and damage and disruption of glucocorticoid-sensitive regions of the cerebello-thalamo-cortical network.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study was conducted from December 2016 to July 2019 in a single pediatric cancer tertiary care center. Participants included survivors of childhood ALL who were more than 5 years from cancer diagnosis, age 8 years or older, and treated on an institutional chemotherapy-only protocol. Age-matched community members were recruited as a control group. Data were analyzed from August 2017 to August 2020.

EXPOSURE

ALL treatment using chemotherapy-only protocols.

MAIN OUTCOMES AND MEASURES

This study compared brain volumes between survivors and individuals in a community control group and examined associations among survivors of methotrexate and dexamethasone exposure with neurocognitive outcomes. Functional and effective connectivity measures were compared between survivors with and without cognitive impairment. The Rey-Osterrieth complex figure test, a neurocognitive evaluation in which individuals are asked to copy a figure and then draw the figure from memory, was scored according to published guidelines and transformed into age-adjusted z scores based on nationally representative reference data and used to measure organization and planning deficits. β values for neurocognitive tests represented the amount of change in cerebellar volume or chemotherapy exposure associated with 1 SD change in neurocognitive outcome by z score (mm3/1 SD in z score for cerebellum, mm3/[g×hr/L] for dexamethasone and methotrexate AUC, and mm3/intrathecal count for total intrathecal count).

RESULTS

Among 302 eligible individuals, 218 (72%) participated in the study and 176 (58%) had usable magnetic resonance imaging (MRI) results. Among these, 89 (51%) were female participants and the mean (range) age was 6.8 (1-18) years at diagnosis and 14.5 (8-27) years at evaluation. Of 100 community individuals recruited as the control group, 82 had usable MRI results; among these, 35 (43%) were female individuals and the mean (range) age was 13.8 (8-26) years at evaluation. There was no significant difference in total brain volume between survivors and individuals in the control group. Survivors of both sexes showed decreased mean (SD) cerebellar volumes compared with the control population (female: 70 568 [6465] mm3 vs 75 134 [6780] mm3; P < .001; male: 77 335 [6210] mm3 vs 79 020 [7420] mm3; P < .001). In female survivors, decreased cerebellar volume was associated with worse performance in Rey-Osterrieth complex figure test (left cerebellum: β = 55.54; SE = 25.55; P = .03; right cerebellum: β = 52.57; SE = 25.50; P = .04) and poorer dominant-hand motor processing speed (ie, grooved pegboard performance) (left cerebellum: β = 82.71; SE = 31.04; P = .009; right cerebellum: β = 91.06; SE = 30.72; P = .004). In female survivors, increased number of intrathecal treatments (ie, number of separate injections) was also associated with Worse Rey-Osterrieth test performance (β = -0.154; SE = 0.063; P = .02), as was increased dexamethasone exposure (β = -0.0014; SE = 0.0005; P = .01). Executive dysfunction was correlated with increased global efficiency between smaller brain regions (Pearson r = -0.24; P = .01) compared with individuals without dysfunction. Anatomical connectivity showed differences between impaired and nonimpaired survivors. Analysis of variance of effective-connectivity weights identified a significant interaction association (F = 3.99; P = .02) among the direction and strength of connectivity between the cerebellum and DLPFC, female sex, and executive dysfunction. Finally, no effective connectivity was found between the precuneus and DLPFC in female survivors with executive dysfunction.

CONCLUSIONS AND RELEVANCE

These findings suggest that dexamethasone exposure was associated with smaller cerebello-thalamo-cortical regions in survivors of ALL and that disruption of effective connectivity was associated with impairment of executive function in female survivors.

Assessment of Executive Functions after Treatment of Childhood Acute Lymphoid Leukemia: a Systematic Review

Individuals treated for childhood acute lymphoblastic leukemia (ALL) have a high survival rate. This fact, however, may lead to neurocognitive impairments in survivors, as shown in some studies. The prefrontal cortex and executive functions seem to be particularly vulnerable due to the late maturation in the development process. Executive impairments have been associated with poorer quality of life in childhood cancer survivors. A systematic review was carried out with studies that assessed executive functions in childhood ALL survivors.\ Studies were collected from five electronic databases: MEDLINE (PubMed); PsycInfo; WebOfScience; LILACS and IBECS. Eighty-four studies were retrieved from the database search, of which 50 were read in full and 26 met the inclusion criteria. The studies were heterogeneous as to the instruments used to assess executive function, the skills assessed and the comparison methods. Despite some discrepancies, ALL survivors seem to exhibit poorer executive functioning than typical controls, but this result did not hold true when subjects were compared to normative mean. Changes in brain structure and dynamics resulting from the disease itself, the toxicity of the treatment and difficulties in coping with the stress during treatment may be related to executive impairments in ALL survivors. Discussion proposed standardized methods and measures for assessing executive functioning in children during and after ALL treatment.

Pathogenesis, Assessments, and Management of Chemotherapy-Related Cognitive Impairment (CRCI): An Updated Literature Review

There are various cancer treatments at present, and chemotherapy is one of the main methods. Chemotherapy-related cognitive impairment (CRCI), as one of the side effects of chemotherapy, has gradually attracted the attention of more and more researchers. CRCI has been verified by subjective reports and objective neuropsychological tests so far. But oncologists' understanding of it and its treatments are still incomplete. In this review, we mainly give a comprehensive overview of the mechanism of CRCI, then describe a variety of evaluation methods, and finally summarize the treatment approaches under current medical conditions and compare it with an excellent article published in 2015 with the aim of providing directions for future research and better understanding of CRCI for clinicians.

Neuroanatomical abnormalities related to dexamethasone exposure in survivors of childhood acute lymphoblastic leukemia

Survivors of childhood acute lymphoblastic leukemia (ALL) treated with chemotherapy only are at risk for neurocognitive impairment. Regions of interest were identified a priori based on glucocorticoid receptor distribution, and sex-stratified multivariable linear regression models were used to test associations between brain MRI morphology and total number of intrathecal injections, and serum concentration of dexamethasone and methotrexate. Compared with controls, ALL survivors have persistently smaller volumes in the bilateral cerebellum (P < 0.005), hippocampal subregions (P < 0.03), temporal lobe regions (P < 0.03), frontal lobe regions (P < 0.04), and parietal lobe regions (precuneus; P < 0.002). Long-term problems with learning may be related to residual posttreatment brain differences.

Melatonin rescued methotrexate-induced spatial deficit and hyperhomocysteinemia and increased asymmetric dimethylarginine in plasma and dorsal hippocampus in developing rats

AIMS

With the improvement of the survival rates in children acute lymphoblastic leukemia (ALL), some children ALL survivors show impaired cognitive function. Methotrexate (MTX), an essential component in ALL treatment, has been reported to be related to neurologic sequelae and to increased oxidative stress through its interactions with enzymes in the folate pathway. Asymmetric dimethylarginine (ADMA) is the main endogenous inhibitor of nitric oxide synthase, and increased ADMA may result from increased oxidants. Melatonin is an antioxidant; however, its role in MTX neuropathy is not well studied. We developed a rat model mimicking child ALL treatment to explore peripheral and central homocysteine and ADMA regulation after MTX and found potential treatment choice.

MAIN METHODS

Preweaning male Sprague-Dawley rats were used in this study. Experiment 1 evaluated spatial performance in rats with intrathecal (IT) MTX, intraperitoneal (IP) MTX, or combined IT and IP MTX, protocols mimicking ALL treatment in children. Experiment 2 focused on rats with combined IT and IP MTX, evaluating spatial performance and plasma and dorsal hippocampal homocysteine and ADMA levels, their regulation, and the protective effect of melatonin.

KEY FINDINGS

Combined IT and IP MTX treatment caused in spatial deficits in developing rats, and melatonin restored the spatial performance. Alterations in peripheral and central homocysteine and ADMA concentrations and their regulation were found and could be alleviated by melatonin treatment.

SIGNIFICANCES

Combined IP and IT MTX treatment caused spatial deficits in developing rats. Melatonin could restore spatial performance through alleviating the effects on the imbalance of oxidative stress.

Influence of Inflammatory and Oxidative Stress Pathways on Longitudinal Symptom Experiences in Children With Leukemia

PURPOSE

The purpose of this study was to explore the influence of oxidative stress (F2-isoprostanes) and inflammatory (interleukin [IL]-8) biomarkers on symptom trajectories during the first 18 months of childhood leukemia treatment.

METHOD

A repeated-measures design was used to evaluate symptoms experienced by 218 children during treatment. A symptom cluster (fatigue, pain, and nausea) was explored over four time periods: initiation of post-induction therapy, 4 and 8 months into post-induction therapy, and the beginning of maintenance therapy (12 months postinduction). F2-isoprostanes and IL-8 were evaluated in cerebrospinal fluid (CSF) samples collected at baseline (diagnosis) and then at the four time periods. The longitudinal relationships of these biomarkers with the symptom cluster were examined using the longitudinal parallel process.

RESULTS

Pain and fatigue levels were highest during the post-induction phases of treatment and decreased slightly during maintenance therapy, while nausea scores were relatively stable. Even in the later phases of treatment, children continued to experience symptoms. CSF levels of the biomarkers increased during the post-induction phases of treatment. Early increases in the biomarkers were associated with more severe symptoms during the same period; patients who had increased biomarkers over time also experienced more severe symptoms over time.

CONCLUSIONS

Findings reveal that children experienced symptoms throughout the course of leukemia treatment and support hypothesized longitudinal relationships of oxidative stress and inflammatory biomarkers with symptom severity. Activation of the biomarker pathways during treatment may explain underlying mechanisms of symptom experiences and identify which children are at risk for severe symptoms.

Brain Connectivity and Cognitive Flexibility in Nonirradiated Adult Survivors of Childhood Leukemia

Background

This study aimed to assess functional and structural brain connectivity in adult childhood leukemia survivors and the link with cognitive functioning and previously identified risk factors such as intrathecal methotrexate dose and age at start of therapy.

Methods

Thirty-one nonirradiated adult childhood leukemia survivors and 35 controls underwent cognitive testing and multimodal magnetic resonance imaging (resting state functional MRI, T1-weighted, diffusion-weighted, and myelin water imaging [MWI]). Analyses included dual regression, voxel-based morphometry, advanced diffusion, and MWI modeling techniques besides stepwise discriminant function analysis to identify the most affected executive cognitive domain. Correlations with discrete intrathecal MTX doses and (semi)continuous variables were calculated using Spearman's rank and Pearson's correlation, respectively. All correlation tests were two-sided. Positive and negative T-contrasts in functional and structural MRI analysis were one-sided.

Results

Survivors demonstrated lower functional connectivity between the default mode network (DMN) and inferior temporal gyrus (ITG; P < .008). Additionally, we observed higher fractional anisotropy (FA; P = .04) and lower orientation dispersion index (ODI; P = .008) at the left centrum semiovale, which could-given that several fiber bundles cross this region-suggest selective reduced integrity of the respective white matter tracts. Set shifting reaction time, a measure of cognitive flexibility, was mostly impaired and correlated with lower FA (r = -0.53, P = .003) and higher ODI (r = 0.40, P = .04) in survivors but not with DMN-ITG connectivity. There were no statistically significant differences between survivors and controls in WM or GM volume, nor was there a statistically significant correlation between imaging measurements and age at start of therapy or intrathecal methotrexate dose.

Conclusions

Adult, nonirradiated childhood leukemia survivors show altered brain connectivity, which is linked with cognitive flexibility.

Neurocognitive Sequelae in Adult Childhood Leukemia Survivors Related to Levels of Phosphorylated Tau

Central nervous system-directed prophylactic chemotherapy increases survival in childhood leukemia, but possible late neurocognitive sequelae remain a concern. We compared intellectual performance (WAIS IV), memory (AVLT), and executive functioning (ANT) between adult leukemia survivors (n = 31) and control individuals (n = 35). In survivors, cerebrospinal fluid (CSF) levels of phosphorylated Tau (p-Tau) during treatment and total intrathecal methotrexate dose correlated with adult intellectual performance (Pearson's and Spearman's coefficients, respectively). Long-term memory and attentional control, both maturing before survivors' mean age at diagnosis, were unaffected (P > .05 on all four subtests), in contrast to cognitive flexibility and information processing (P < .05 for eight of the subtests), which mature during adolescence. CSF p-Tau and methotrexate dose negatively correlated with intellectual performance (r = -0.414, P = .04 and r = -0.484, P = .007, respectively), but not with each other (r = 0.219, P = .29). These data identify CSF p-Tau as a predictor of late neurocognitive sequelae (in addition to methotrexate dose). Early identification of children at risk could inspire interventions to prevent or remediate chemotherapy-induced cognitive sequelae.

Chemotherapy and the pediatric brain

Survival rates of children with cancer are steadily increasing. This urges our attention to neurocognitive and psychiatric outcomes, as these can markedly influence the quality of life of these children. Neurobehavioral morbidity in childhood cancer survivors affects diverse aspects of cognitive function, which can include attention, memory, processing speed, intellect, academic achievement, and emotional health. Reasons for neurobehavioral morbidity are multiple with one major contributor being chemotherapy-induced central nervous system (CNS) toxicity. Clinical studies investigating the effects of chemotherapy on the CNS in children with cancer have reported causative associations with the development of leukoencephalopathies as well as smaller regional grey and white matter volumes, which have been found to correlate with neurocognitive deficits.Preclinical work has provided compelling evidence that chemotherapy drugs are potent neuro- and gliotoxins in vitro and in vivo and can cause brain injury via excitotoxic and apoptotic mechanisms. Furthermore, chemotherapy triggers DNA (deoxyribonucleic acid) damage directly or through increased oxidative stress. It can shorten telomeres and accelerate cell aging, cause cytokine deregulation, inhibit hippocampal neurogenesis, and reduce brain vascularization and blood flow. These mechanisms, when allowed to operate on the developing brain of a child, have high potential to not only cause brain injury, but also alter crucial developmental events, such as myelination, synaptogenesis, neurogenesis, cortical thinning, and formation of neuronal networks.This short review summarizes key publications describing neurotoxicity of chemotherapy in pediatric cancers and potential underlying pathomechanisms.

Methotrexate causes persistent deficits in memory and executive function in a juvenile animal model

Methotrexate is a dihydrofolate reductase inhibitor widely employed in curative treatment for children with acute lymphoblastic leukemia (ALL). However, methotrexate administration is also associated with persistent cognitive deficits among long-term childhood cancer survivors. Animal models of methotrexate-induced cognitive deficits have primarily utilized adult animals. The purpose of present study is to investigate the neurotoxicity of methotrexate in juvenile rats and its relevant mechanisms. The doses and schedule of systemic and intrathecal methotrexate, given from post-natal age 3-7 weeks, were chosen to model the effects of repeated methotrexate dosing on the developing brains of young children with ALL. This methotrexate regimen had no visible acute toxicity and no effect on growth. At 15 weeks of age (8 weeks after the last methotrexate dose) both spatial pattern memory and visual recognition memory were impaired. In addition, methotrexate-treated animals demonstrated impaired performance in the set-shifting assay, indicating decreased cognitive flexibility. Histopathological analysis demonstrated decreased cell proliferation in methotrexate-treated animals compared to controls, as well as changes in length and thickness of the corpus callosum. Moreover, methotrexate suppressed microglia activation and RANTES production. In conclusion, our study demonstrated that a clinically relevant regimen of systemic and intrathecal methotrexate induces persistent deficits in spatial pattern memory, visual recognition memory and executive function, lasting at least 8 weeks after the last injection. The mechanisms behind methotrexate-induced deficits are likely multifactorial and may relate to suppression of neurogenesis, alterations in neuroinflammation and microglial activation, and structural changes in the corpus callosum.

Association of Cerebrospinal Fluid Biomarkers of Central Nervous System Injury With Neurocognitive and Brain Imaging Outcomes in Children Receiving Chemotherapy for Acute Lymphoblastic Leukemia

Importance

Little is known about treatment-related neurotoxic mechanisms in children with acute lymphoblastic leukemia (ALL) treated with chemotherapy only.

Objective

To examine concentration of cerebrospinal fluid (CSF) biomarkers of brain injury at ALL diagnosis and during cancer therapy and to evaluate associations with long-term neurocognitive and neuroimaging outcomes and relevant genetic polymorphisms.

Design, Setting, and Participants

This prospective cohort study included 235 patients with ALL who received a chemotherapy-only protocol. Patients provided CSF samples after diagnosis and throughout treatment. At 5 or more years after the diagnosis, 138 (69.7%) of 198 eligible survivors participated in long-term follow-up assessments. Children were treated from June 1, 2000, through October 31, 2010. Follow-up was completed on October 21, 2014, and data were analyzed from August 1, 2015, through September 30, 2016.

Exposures

Plasma concentration of high-dose intravenous methotrexate sodium and number of triple intrathecal chemotherapy injections.

Main Outcomes and Measures

The CSF samples were assayed at 5 points from diagnosis to reinduction for biomarkers of myelin degradation (myelin basic protein [MBP]), neuronal damage (nerve growth factor [NGF] and total and phosphorylated tau protein), astrogliosis (glial fibrillary acidic protein [GFAP]), and neuroinflammation (chitotriosidase). DNA was genotyped for polymorphisms in drug metabolism, oxidative stress, and neurodevelopment. Leukoencephalopathy was evaluated by brain imaging. At 5 or more years after the diagnosis, survivors completed neurocognitive testing and brain imaging of white matter integrity.

Results

Among the 235 patients with CSF samples (120 boys [51.1%] and 115 girls [48.9%]; mean [SD] age at diagnosis, 6.8 [4.7] years), MBP and GFAP levels were elevated at baseline and through consolidation. The number of intrathecal injections was positively correlated with NGF level increase at consolidation (r = 0.19; P = .005). Increases in GFAP (risk ratio [RR], 1.23; 95% CI, 1.09-1.40), MBP (RR, 1.06; 95% CI, 1.01-1.11), and total tau (RR, 1.76; 95% CI, 1.11-2.78) levels were associated with a higher risk for leukoencephalopathy and higher apparent diffusion coefficient in frontal lobe white matter 5 years after diagnosis (standardized estimate, 0.05; P < .001). Increase in total tau at consolidation was associated with worse attention (omissions z score estimate, -0.20; P = .04).

Conclusions and Relevance

Glial injury may be present at diagnosis of ALL. Neuronal injury was associated with intrathecal chemotherapy. The CSF biomarkers may be useful in identifying individuals at risk for worse neurologic outcomes, particularly those with genetic susceptibility to poor brain function.

Advanced MR diffusion imaging and chemotherapy-related changes in cerebral white matter microstructure of survivors of childhood bone and soft tissue sarcoma?

With the increase of survival rates of pediatric cancer patients, the number of children facing potential cognitive sequelae has grown. Previous adult studies suggest that white matter (WM) microstructural changes may contribute to cognitive impairment. This study aims to investigate WM microstructure in childhood bone and soft tissue sarcoma. Differences in (micro-)structure can be investigated using diffusion MRI (dMRI). The typically used diffusion tensor model (DTI) assumes Gaussian diffusion, and lacks information about fiber populations. In this study, we compare WM structure of childhood bone and soft tissue sarcoma survivors (n = 34) and matched controls (n = 34), combining typical and advanced voxel-based models (DTI and NODDI model, respectively), as well as recently developed fixel-based models (for estimations of intra-voxel differences, apparent fiber density [AFD] and fiber cross-section [FC]). Parameters with significant findings were compared between treatments, and correlated with subscales of the WAIS-IV intelligence test, age at diagnosis, age at assessment and time since diagnosis. We encountered extensive regions showing lower fractional anisotropy, overlapping with both significant NODDI parameters and fixel-based parameters. In contrast to these diffuse differences, the fixel-based measure of AFD was reduced in the cingulum and corpus callosum only. Furthermore, AFD of the corpus callosum was significantly predicted by chemotherapy treatment and correlated positively with time since diagnosis, visual puzzles and similarities task scores. This study suggests altered WM structure of childhood bone and soft tissue sarcoma survivors. We conclude global chemotherapy-related changes, with particular vulnerability of centrally located WM bundles. Finally, such differences could potentially recover after treatment.

PAN-811 prevents chemotherapy-induced cognitive impairment and preserves neurogenesis in the hippocampus of adult rats

Chemotherapy-induced cognitive impairment (CICI) occurs in a substantial proportion of treated cancer patients, with no drug currently available for its therapy. This study investigated whether PAN-811, a ribonucleotide reductase inhibitor, can reduce cognitive impairment and related suppression of neurogenesis following chemotherapy in an animal model. Young adult rats in Chemo and Chemo+PAN-811 groups received 3 intraperitoneal (i.p.) injections of methotrexate (MTX) and 5-fluorouracil (5-FU), and those in Saline and Saline+PAN-811 groups received equal volumes of physiological saline at 10-day intervals. PAN-811 in saline was delivered through i.p. injection, 10 min following each saline (Saline+PAN-811 group) or MTX/5-FU (Chemo+PAN-811 group) treatment, while equal volumes of saline were delivered to Saline and Chemo groups. Over Days 31–66, rats were administered tests of spatial memory, nonmatching-to-sample rule learning, and discrimination learning, which are sensitive to dysfunction in hippocampus, frontal lobe and striatum, respectively. On Day 97, neurogenesis was immnunohistochemically evaluated by counting doublecortin-positive (DCX⁺) cells in the dentate gyrus (DG). The results demonstrated that the Chemo group was impaired on the three cognitive tasks, but co-administration of PAN-811 significantly reduced all MTX/5-FU-induced cognitive impairments. In addition, MTX/5-FU reduced DCX⁺ cells to 67% of that in Saline control rats, an effect that was completely blocked by PAN-811 co-administration. Overall, we present the first evidence that PAN-811 protects cognitive functions and preserves neurogenesis from deleterious effects of MTX/5-FU. The current findings provide a basis for rapid clinical translation to determine the effect of PAN-811 on CICI in human.

Neurocognitive dysfunction in hematopoietic cell transplant recipients: expert review from the late effects and Quality of Life Working Committee of the CIBMTR and complications and Quality of Life Working Party of the EBMT

Hematopoietic cell transplantation (HCT) is a potentially curative treatment for children and adults with malignant and non-malignant diseases. Despite increasing survival rates, long-term morbidity following HCT is substantial. Neurocognitive dysfunction is a serious cause of morbidity, yet little is known about neurocognitive dysfunction following HCT. To address this gap, collaborative efforts of the Center for International Blood and Marrow Transplant Research and the European Society for Blood and Marrow Transplantation undertook an expert review of neurocognitive dysfunction following HCT. In this review, we define what constitutes neurocognitive dysfunction, characterize its risk factors and sequelae, describe tools and methods to assess neurocognitive function in HCT recipients, and discuss possible interventions for HCT patients with this condition. This review aims to help clinicians understand the scope of this health-related problem, highlight its impact on well-being of survivors, and to help determine factors that may improve identification of patients at risk for declines in cognitive functioning after HCT. In particular, we review strategies for preventing and treating neurocognitive dysfunction in HCT patients. Lastly, we highlight the need for well-designed studies to develop and test interventions aimed at preventing and improving neurocognitive dysfunction and its sequelae following HCT.

Neurocognitive Dysfunction in Hematopoietic Cell Transplant Recipients: Expert Review from the Late Effects and Quality of Life Working Committee of the Center for International Blood and Marrow Transplant Research and Complications and Quality of Life Working Party of the European Society for Blood and Marrow Transplantation

Hematopoietic cell transplantation (HCT) is a potentially curative treatment for children and adults with malignant and nonmalignant diseases. Despite increasing survival rates, long-term morbidity after HCT is substantial. Neurocognitive dysfunction is a serious cause of morbidity, yet little is known about neurocognitive dysfunction after HCT. To address this gap, collaborative efforts of the Center for International Blood and Marrow Transplant Research and the European Society for Blood and Marrow Transplantation undertook an expert review of neurocognitive dysfunction after HCT. In this review we define what constitutes neurocognitive dysfunction, characterize its risk factors and sequelae, describe tools and methods to assess neurocognitive function in HCT recipients, and discuss possible interventions for HCT patients with this condition. This review aims to help clinicians understand the scope of this health-related problem, highlight its impact on well-being of survivors, and help determine factors that may improve identification of patients at risk for declines in cognitive functioning after HCT. In particular, we review strategies for preventing and treating neurocognitive dysfunction in HCT patients. Finally, we highlight the need for well-designed studies to develop and test interventions aimed at preventing and improving neurocognitive dysfunction and its sequelae after HCT.

Uric Acid and Neurocognitive Function in Survivors of Childhood Acute Lymphoblastic Leukemia Treated with Chemotherapy Only

BACKGROUND

Hyperuricemia is implicated in cardiovascular and cerebrovascular diseases. This study evaluated associations between uric acid (UA), cardiovascular health, and neurocognitive function in adolescent and adult survivors of childhood acute lymphoblastic leukemia treated with chemotherapy only.

METHODS

126 adolescent [mean (SD) age 14.6 (5.0); 7.8 (1.7) years postdiagnosis] and 226 adult survivors [age 25.4 (4.2) years; 18.1 (4.4) years postdiagnosis] completed comprehensive neurocognitive testing. Concurrent UA measurements were conducted for both groups. For adult survivors, cardiovascular risk factors were assessed, and UA measurements during adolescence [12.3 (4.0) years before neurocognitive testing] were also collected. UA levels were categorized into quartiles for age- and gender-based ranking, and associations with neurocognitive outcomes were examined.

RESULTS

Survivors demonstrated worse attention, processing speed, and executive functions than population norms (P values < 0.05). Adolescent survivors with elevated UA had poorer attention (P = 0.04), visual-processing speed (P = 0.03), and cognitive flexibility (P = 0.02). UA was not associated with neurocognitive outcomes in adult survivors. Adult survivors developed dyslipidemia (46%), hypertension (32%), and abdominal obesity (26%), and high UA during adolescence was associated with these cardiovascular risk factors as adults (all P values < 0.01). Fine-motor processing speed was slower in adult survivors with dyslipidemia (P = 0.04) and abdominal obesity (P = 0.04). Poorer attention was marginally associated with hypertension (P = 0.06).

CONCLUSIONS

Elevated UA is associated with neurocognitive performance in adolescent survivors. In adult survivors, relative elevation of UA during adolescence was predictive of cardiovascular health, which was associated with poorer neurocognitive outcomes.

IMPACT

Future studies should evaluate the mediating role of chronic cardiovascular health conditions between elevated UA and subsequent neurocognitive impairment in survivors. Cancer Epidemiol Biomarkers Prev; 25(8); 1259-67. ©2016 AACR.

Effects of Intraventricular Methotrexate on Neuronal Injury and Gene Expression in a Rat Model

Central nervous system (CNS)-directed treatment for acute lymphoblastic leukemia, used to prevent disease recurrence in the brain, is essential for survival. Systemic and intrathecal methotrexate, commonly used for CNS-directed treatment, have been associated with cognitive problems during and after treatment. The cortex, hippocampus, and caudate putamen, important brain regions for learning and memory, may be involved in methotrexate-induced brain injury. Objectives of this study were to (1) quantify neuronal degeneration in selected regions of the cortex, hippocampus, and caudate putamen and (2) measure changes in the expression of genes with known roles in oxidant defense, apoptosis/inflammation, and protection from injury. Male Sprague Dawley rats were administered 2 or 4 mg/kg of methotrexate diluted in artificial cerebrospinal fluid (aCSF) or aCSF only into the left cerebral lateral ventricle. Gene expression changes were measured using customized reverse transcription (RT)2 polymerase chain reaction arrays. The greatest percentage of degenerating neurons in methotrexate-treated animals was in the medial region of the cortex; percentage of degenerating neurons in the dentate gyrus and cornu ammonis 3 regions of the hippocampus was also greater in rats treated with methotrexate compared to perfusion and vehicle controls. There was a greater percentage of degenerating neurons in the inferior cortex of control versus methotrexate-treated animals. Eight genes involved in protection from injury, oxidant defense, and apoptosis/inflammation were significantly downregulated in different brain regions of methotrexate-treated rats. To our knowledge, this is the first study to investigate methotrexate-induced injury in selected brain regions and gene expression changes using a rat model of intraventricular drug administration.

The Role of Oxidative Stress in Etiopathogenesis of Chemotherapy Induced Cognitive Impairment (CICI)-"Chemobrain"

Chemobrain or chemotherapy induced cognitive impairment (CICI) represents a new clinical syndrome characterised by memory, learning and motor function impairment. As numerous patients with cancer are long-term survivors, CICI represent a significant factor which may interfere with their quality of life. However, this entity CICI must be distinguished from other cognitive syndromes and addressed accordingly. At the present time, experimental and clinical research suggests that CICI could be induced by numerous factors including oxidative stress. This type of CNS injury has been previously described in cancer patients treated with common anti-neoplastic drugs such as doxorubicine, carmustine, methotrexate and cyclophosphamide. It seems that all these pharmacological factors promote neuronal death through a final common pathway represented by TNF alpha (tumour necrosis factor). However, as cancer in general is diagnosed more commonly in the aging population, the elderly oncological patient must be treated with great care since aging per se is also impacted by oxidative stress and potentiually by TNF alpha deleterious action on brain parenchyma. In this context, some patients may develop cognitive dysfunction well before the appearance of CICI. In addition, chemotherapy may worsen their cognitive function. Therefore, at the present time, there is an acute need for development of effective therapeutic methods to prevent CICI as well as new methods of early CICI diagnosis.

Chemotherapy-induced neurotoxicity in pediatric solid non-CNS tumor patients: An update on current state of research and recommended future directions

Neurocognitive sequelae are known to be induced by cranial radiotherapy and central-nervous-system-directed chemotherapy in childhood Acute Lymphoblastic Leukemia (ALL) and brain tumor patients. However, less evidence exists for solid non-CNS-tumor patients. To get a better understanding of the potential neurotoxic mechanisms of non-CNS-directed chemotherapy during childhood, we performed a comprehensive literature review of this topic. Here, we provide an overview of preclinical and clinical studies investigating neurotoxicity associated with chemotherapy in the treatment of pediatric solid non-CNS tumors. Research to date suggests that chemotherapy has deleterious biological and psychological effects, with animal studies demonstrating histological evidence for neurotoxic effects of specific agents and human studies demonstrating acute neurotoxicity. Although the existing literature suggests potential neurotoxicity throughout neurodevelopment, research into the long-term neurocognitive sequelae in survivors of non-CNS cancers remains limited. Therefore, we stress the critical need for neurodevelopmental focused research in children who are treated for solid non-CNS tumors, since they are at risk for potential neurocognitive impairment.

Trajectories of Obesity and Overweight Rates Among Survivors of Childhood Acute Lymphoblastic Leukemia

PURPOSE/OBJECTIVES

To describe the trajectories of obesity/overweight rates by age group among survivors of childhood acute lymphoblastic leukemia (ALL) from diagnosis through several years post-therapy.

DESIGN

Longitudinal, descriptive.

SETTING

Hematology/oncology clinic in the southwestern United States.

SAMPLE

62 child and adolescent ALL survivors receiving treatment and follow-up care from 1999-2013.

METHODS

Retrospective chart review of height, weight, and body mass index.

MAIN RESEARCH VARIABLES

Annual obesity/overweight rates and developmental age groups.

FINDINGS

Different trajectories of obesity/overweight rates existed among age groups. Forty-seven percent of adolescents met the Centers for Disease Control and Prevention criteria for obesity/overweight status at some point following diagnosis, compared to 68% of school-age and 73% of preschool children. Preschool children demonstrated the most rapid rate increase following diagnosis, with a particularly susceptible period in the years immediately following therapy. Obesity/overweight persistence was most characteristic of school-age children.

CONCLUSIONS

Important variations in rate and pattern of weight status trajectories exist by age group, demonstrating that children diagnosed with ALL during the preschool and school-age developmental years have the greatest vulnerability of developing obesity/overweight status.

IMPLICATIONS FOR NURSING

Obesity/overweight prevention efforts are greatly needed in children with ALL, and efforts should occur before ALL treatment completion in preschool and school-age children.

Monitoring and Assessment of Neuropsychological Outcomes as a Standard of Care in Pediatric Oncology

Central nervous system cancers or exposure to CNS-directed therapies increase risk for neuropsychological deficits. There are no accepted guidelines for assessment of neuropsychological functioning in this population. A multifaceted literature search was conducted and relevant literature reviewed to inform the guidelines. Studies of neuropsychological outcomes are widely documented in the pediatric oncology literature. There is strong evidence of need for neuropsychological assessment, but insufficient evidence to guide the timing of assessment, nor to recommend specific interventions. Children with brain tumors and others at high risk for neuropsychological deficits should be monitored and assessed for neuropsychological deficits.

PAN-811 Blocks Chemotherapy Drug-Induced In Vitro Neurotoxicity, While Not Affecting Suppression of Cancer Cell Growth

Chemotherapy often results in cognitive impairment, and no neuroprotective drug is now available. This study aimed to understand underlying neurotoxicological mechanisms of anticancer drugs and to evaluate neuroprotective effects of PAN-811. Primary neurons in different concentrations of antioxidants (AOs) were insulted for 3 days with methotrexate (MTX), 5-fluorouracil (5-FU), or cisplatin (CDDP) in the absence or presence of PAN-811·Cl·H₂O. The effect of PAN-811 on the anticancer activity of tested drugs was also examined using mouse and human cancer cells (BNLT3 and H460) to assess any negative interference. Cell membrane integrity, survival, and death and intramitochondrial reactive oxygen species (ROS) were measured. All tested anticancer drugs elicited neurotoxicity only under low levels of AO and elicited a ROS increase. These results suggested that ROS mediates neurotoxicity of tested anticancer drugs. PAN-811 dose-dependently suppressed increased ROS and blocked the neurotoxicity when neurons were insulted with a tested anticancer drug. PAN-811 did not interfere with anticancer activity of anticancer drugs against BNLT3 cells. PAN-811 did not inhibit MTX-induced death of H460 cells but, interestingly, demonstrated a synergistic effect with 5-FU or CDDP in reducing cancer cell viability. Thus, PAN-811 can be a potent drug candidate for chemotherapy-induced cognitive impairment.

Neurocognitive outcomes in long-term survivors of childhood acute lymphoblastic leukemia treated on contemporary treatment protocols: A systematic review

The intensified administration of chemotherapeutic drugs has gradually replaced cranial radiation therapy (CRT) for the treatment of childhood acute lymphoblastic leukemia (ALL). While CRT is often implicated in neurocognitive impairment in ALL survivors, there is a paucity of the literature that evaluates the persistence of neurocognitive deficits in long-term survivors of pediatric ALL who were treated with contemporary chemotherapy-only protocols. Results from this systematic review concurred to the probable cognitive-sparing effect of chemotherapy-based protocols over CRT in long-term survivors. However, coupled with multiple intrinsic and extrinsic factors, survivors who received chemotherapy treatment still suffered from apparent cognitive impairment, particularly in the attention and executive function domains. Notably, there is evidence to suggest that the late neurotoxic effect of methotrexate on survivors' neurocognitive performance may be dose-related. This review also recommends future pharmacokinetic, neuroimaging and genetic studies to illuminate the multifactorial nature of this subject matter and discusses the potential value of neurochemical, physiological, inflammatory and genetic markers for the prediction of susceptibility to neurocognitive impairment in long-term survivors of childhood ALL.

Evaluation of Biomarkers of Oxidative Stress and Apoptosis in Patients With Severe Methotrexate Neurotoxicity: A Case Series

Central nervous system (CNS) treatment is an essential part of acute lymphocytic leukemia (ALL) therapy, and the most common CNS treatment is intrathecal (IT) and high-dose intravenous (IV) methotrexate (MTX). Treatment with MTX may cause neurotoxicity, which is often accompanied by neurologic changes, delays in treatment, and prolonged hospital stays. This article reports clinical presentations of 3 patients with severe MTX toxicity as well as levels of oxidative stress and apoptosis biomarkers in cerebrospinal fluid (CSF). Oxidative stress was measured by oxidized phosphatidylcholine (PC), oxidized phosphatidylinositol (PI), and F2 isoprostanes; apoptosis was measured by caspase 3/7 activity. Most consistent biomarker changes in all 3 cases were increases in caspase 3/7 and F2 isoprostanes prior to acute toxicity while increases in oxidized phospholipids occurred slightly later. Progressive increases in F2 isoprostanes and caspase 3/7 activity prior to and/or during acute toxicity suggests MTX induces oxidative stress and an associated increase in apoptosis. These findings support the role of oxidative stress in MTX-related neurotoxicity.

The potential utility of parent-reported attention screening in survivors of childhood cancer to identify those in need of comprehensive neuropsychological evaluation

BACKGROUND

Survivors of childhood cancer are at risk for neuropsychological late effects, yet identifying those in need of evaluation and obtaining needed services can be challenging for the medical team. Finding time- and cost-effective screening measures that can be used to identify children in need of evaluation is a clinical priority. Our objective was to investigate the association between parent-rated attention problems and related neuropsychological impairments in childhood cancer survivors as a means of identifying those at high risk for difficulties.

METHODS

Cognitive and psychosocial data of survivors who completed neuropsychological evaluations were retrospectively abstracted. Parents of 70 survivors of pediatric cancer (mean age, 11.6 years) completed the Conners Parent Rating Scale and the Child Behavior Checklist. Children also completed a measure of intellectual functioning. The 18 symptoms of inattention and hyperactivity were abstracted from the Conners questionnaire, and participants were classified according to whether or not they met attention deficit/hyperactivity disorder (ADHD) symptom criteria (≥6 inattentive symptoms).

RESULTS

Survivors who met symptom criteria for ADHD (27%) demonstrated greater impairments in IQ and working memory, but not processing speed, than survivors who did not. Meeting ADHD symptom criteria was also associated with greater externalizing and social problems but not more internalizing symptoms. ADHD symptom screening was associated with low sensitivity (range = 26.3%-69.2%) but stronger specificity (range = 75.0%-82.7%) for neuropsychological difficulties.

CONCLUSION

Parental ratings of attentional symptoms may be a useful way to screen survivors who may be in need of a full neuropsychological assessment.

Methotrexate-related response on human peripheral blood mononuclear cells may be modulated by the Ala16Val-SOD2 gene polymorphism

Methotrexate (MTX) is a folic acid antagonist used in high doses as an anti-cancer treatment and in low doses for the treatment of some autoimmune diseases. MTX use has been linked to oxidative imbalance, which may cause multi-organ toxicities that can be attenuated by antioxidant supplementation. Despite the oxidative effect of MTX, the influence of antioxidant gene polymorphisms on MTX toxicity is not well studied. Therefore, we analyzed here whether a genetic imbalance of the manganese-dependent superoxide dismutase (SOD2) gene could have some impact on the MTX cytotoxic response. An in vitro study using human peripheral blood mononuclear cells (PBMCs) obtained from carriers with different Ala16Val-SOD2 genotypes (AA, VV and AV) was carried out, and the effect on cell viability and proliferation was analyzed, as well as the effect on oxidative, inflammatory and apoptotic markers. AA-PBMCs that present higher SOD2 efficiencies were more resistance to high MTX doses (10 and 100 µM) than were the VV and AV genotypes. Both lipoperoxidation and ROS levels increased significantly in PBMCs exposed to MTX independent of Ala16Val-SOD2 genotypes, whereas increased protein carbonylation was observed only in PBMCs from V allele carriers. The AA-PBMCs exposed to MTX showed decreasing SOD2 activity, but a concomitant up regulation of the SOD2 gene was observed. A significant increase in glutathione peroxidase (GPX) levels was observed in all PBMCs exposed to MTX. However, this effect was more intense in AA-PBMCs. Caspase-8 and -3 levels were increased in cells exposed to MTX, but the modulation of these genes, as well as that of the Bax and Bcl-2 genes involved in the apoptosis pathway, presented a modulation that was dependent on the SOD2 genotype. MTX at a concentration of 10 µM also increased inflammatory cytokines (IL-1β, IL-6, TNFα and Igγ) and decreased the level of IL-10 anti-inflammatory cytokine, independent of SOD2 genetic background. The results suggest that potential pharmacogenetic effect on the cytotoxic response to MTX due differential redox status of cells carriers different SOD2 genotypes.

Oxidative stress in schizophrenia: a case-control study on the effects on social cognition and neurocognition

BACKGROUND

Schizophrenia is a debilitating mental disorder that presents impairments in neurocognition and social cognition. Several studies have suggested that the etiology of schizophrenia can be partly explained by oxidative stress. However, our knowledge about the implications of oxidative stress on illness-related cognitive deficits is still far from being clear. The aim of this work was to study the role of oxidative stress molecules on social cognition and neurocognition in patients with schizophrenia.

METHODS

We assessed the peripheral levels of several molecules associated with oxidative stress, namely nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), homocysteine, superoxide dismutase (SOD) and neurotrophin 4/5 (NT4/5), in forty-one patients with schizophrenia and forty-three healthy participants. A battery of tests to measure neurocognition and social cognition was also administered to the schizophrenia group.

RESULTS

We found that the schizophrenia group presented substantially higher levels of oxidative stress than the control group, as revealed by elevated quantities of the pro-oxidants NO and MDA, and decreased levels of the antioxidants GSH, SOD and NT4/5. Interestingly, the levels of NT4/5, which have been shown to have antioxidant effects, correlated with executive functioning, as measured by two distinct tests (WCST and TMT). However, social cognition and symptom severity were not found to be associated with oxidative stress.

CONCLUSIONS

We propose a protective role of NT4/5 against oxidative stress, which appears to have a potentially beneficial impact on neurocognition in schizophrenia.

Developing interventions for cancer-related cognitive dysfunction in childhood cancer survivors

Survivors of childhood cancer frequently experience cancer-related cognitive dysfunction, commonly months to years after treatment for pediatric brain tumors, acute lymphoblastic leukemia (ALL), or tumors involving the head and neck. Risk factors for cancer-related cognitive dysfunction include young age at diagnosis, treatment with cranial irradiation, use of parenteral or intrathecal methotrexate, female sex, and pre-existing comorbidities. Limiting use and reducing doses and volume of cranial irradiation while intensifying chemotherapy have improved survival and reduced the severity of cognitive dysfunction, especially in leukemia. Nonetheless, problems in core functional domains of attention, processing speed, working memory and visual-motor integration continue to compromise quality of life and performance. We review the epidemiology, pathophysiology and assessment of cancer-related cognitive dysfunction, the impact of treatment changes for prevention, and the broad strategies for educational and pharmacological interventions to remediate established cognitive dysfunction following childhood cancer. The increased years of life saved after childhood cancer warrants continued study toward the prevention and remediation of cancer-related cognitive dysfunction, using uniform assessments anchored in functional outcomes.

Feasibility and preliminary findings from a pilot study of allostatic load in adolescent-young adult childhood cancer survivors and their siblings

Adolescent-young adult (AYA) childhood cancer survivors experience at least 2 types of chronic stress that can increase their risk for cardiovascular disease: the physiological stress of cancer and its treatment and the psychosocial stress inherent in the cancer experience. Their siblings can also experience ongoing cancer-related psychosocial stress. The composite biomarker allostatic load (AL) describes the cumulative impact of responses to chronic stress on interrelated organ systems and risk for stress-related diseases including cardiovascular disease. AL could be useful as a surrogate response indicator in research and care that aims to improve cardiovascular outcomes of childhood cancer. However, the measurement of AL has requirements to which AYA might not agree or adhere. This study aimed to (a) evaluate the feasibility of studying AL in AYA cancer populations and (b) briefly describe preliminary findings concerning psychological distress, cancer-related stress symptoms, health behavior and AL in AYA survivors and their siblings within the context of a small pilot study. The results support the feasibility of studying AL in AYA survivors and their siblings, and also suggest that further study of AL and risk for cardiovascular disease in both groups is indicated.

Everyday executive function in standard-risk acute lymphoblastic leukemia survivors

We aimed to evaluate parent-rated executive function (EF) in pediatric standard risk acute lymphoblastic leukemia (SR-ALL) survivors compared to a healthy comparison (HC) group. We hypothesized that SR-ALL survivors would have greater reported executive dysfunction compared to HC, and that those younger at the time of treatment would demonstrate greater EF difficulties. A sample of 256 SR-ALL survivors evaluated an average nine years after treatment were compared to HC matched for gender, assessment age, and maternal education. Profile analysis was used to compare the groups across EF scales on the BRIEF. The prevalence of clinical elevations in the groups was compared via chi square, and odds ratios were calculated. Regression models were applied to examine the role of age at diagnosis and age at assessment in reported EF. Results indicated that SR-ALL survivors' mean scores of EF are similar to HC, except for flexibility and initiation. Survivors were rated as having clinical impairments with flexibility, initiation, working memory, and emotional control at rates two to three times that of HC. The risk of working memory and self-monitoring deficits was greater in survivors who were older when assessed. There was no relationship between age at diagnosis or treatment regimen on EF. These findings suggest sparing of extensive and severe EF deficits in SR-ALL survivors overall. However, a subset of survivors displays clinically significant executive dysfunction. There appears to be a heightened susceptibility to disrupted metacognitive functions as survivors age. This has implications for how we monitor neurocognitive development and functioning of SR-ALL survivors, and highlights opportunities for cognitive interventions.

Oxidative stress and neurodegenerative disorders

Living cells continually generate reactive oxygen species (ROS) through the respiratory chain during energetic metabolism. ROS at low or moderate concentration can play important physiological roles. However, an excessive amount of ROS under oxidative stress would be extremely deleterious. The central nervous system (CNS) is particularly vulnerable to oxidative stress due to its high oxygen consumption, weakly antioxidative systems and the terminal-differentiation characteristic of neurons. Thus, oxidative stress elicits various neurodegenerative diseases. In addition, chemotherapy could result in severe side effects on the CNS and peripheral nervous system (PNS) of cancer patients, and a growing body of evidence demonstrates the involvement of ROS in drug-induced neurotoxicities as well. Therefore, development of antioxidants as neuroprotective drugs is a potentially beneficial strategy for clinical therapy. In this review, we summarize the source, balance maintenance and physiologic functions of ROS, oxidative stress and its toxic mechanisms underlying a number of neurodegenerative diseases, and the possible involvement of ROS in chemotherapy-induced toxicity to the CNS and PNS. We ultimately assess the value for antioxidants as neuroprotective drugs and provide our comments on the unmet needs.

Brain volume and cognitive function in adult survivors of childhood acute lymphoblastic leukemia

The survival rate for childhood acute lymphoblastic leukemia (ALL) is greater than 80%. However, many of these survivors develop long-term chronic health conditions, with a relatively common late effect being neurocognitive dysfunction. Although neurocognitive impairments have decreased in frequency and severity as treatment has evolved, there is a subset of survivors in the current treatment era that are especially vulnerable to the neurotoxic effects of ALL and its treatment. Additionally, little is known about long-term brain development as survivors mature into adulthood. A recent study by Zeller et al. compared neurocognitive function and brain volume in 130 adult survivors of childhood ALL to 130 healthy adults matched on age and sex. They identified the caudate as particularly sensitive to the neurotoxic effects of chemotherapy. We discuss the implications and limitations of this study, including how their findings support the concept of individual vulnerability to ALL and its treatment.

Brain size and neuropsychological functioning in long-term survivors of pediatric acute lymphoblastic leukemia

With the increased survival of pediatric cancer patients the interest in the late effects of treatments is rapidly increasing. Long-term survival rates for children with acute lymphoblastic leukemia (ALL) now approach 90%. Treatment for ALL includes intensified central nervous system (CNS)-directed therapy, which is associated with risks for long-term neurocognitive effects. It is becoming clear that current therapies can have not only a detrimental effect on IQ, processing speed, and memory, but also on structural changes that lead to permanent alterations of the organization of the CNS. Understanding how the CNS is affected by the treatments is a critical step in evaluating current therapies and developing interventions to decrease the incidence and severity of long-term changes in brain anatomy and function.

F2-isoprostanes: a measure of oxidative stress in children receiving treatment for leukemia

Acute lymphoblastic leukemia (ALL) is the most prevalent and curable cancer among children and adolescents less than 15 years of age in the United States. Essential for cure of childhood ALL is prophylactic treatment of the central nervous system (CNS), with methotrexate (MTX) being the most widely used drug in this treatment. While CNS treatment has contributed to long-term disease-free survival, resulting declines in academic abilities have been reported. There is growing evidence that CNS treatment with MTX increases oxidative stress, a potential mechanism of CNS injury. This article reports changes in oxidative stress, measured by the biomarker F2-isoprostane (F2-IsoP), in the cerebrospinal fluid (CSF) in 47 children with ALL during the first 18 months of treatment. The number of CSF samples ranged from 5 to 14 during postinduction and from 1 to 9 during continuation. Total doses of intrathecal MTX during postinduction were significantly correlated with the mean and highest concentrations of F2-IsoP during postinduction and the mean concentration of F2-IsoP during continuation. F2-IsoP concentrations during postinduction and continuation were higher in children who received more than six doses of intrathecal MTX. New therapies for a highly curable disease such as childhood leukemia have the potential to be individualized in the future, requiring reliable molecular and biochemical markers, such as oxidative stress indicators. Innovative use of biomarkers has the potential to increase our understanding of treatment-related toxicities and associated symptoms and to inform future therapeutic approaches for optimizing cure and quality of life among children with leukemia.

Children's Oncology Group's 2013 blueprint for research: nursing discipline

Integration of the nursing discipline within cooperative groups conducting pediatric oncology clinical trials provides unique opportunities to maximize nursing's contribution to clinical care, and to pursue research questions that extend beyond cure of disease to address important gaps in knowledge surrounding the illness experience. Key areas of importance to the advancement of the nursing discipline's scientific knowledge are understanding the effective delivery of patient/family education, and reducing illness-related distress, both of which are integral to facilitating parental/child coping with the diagnosis and treatment of childhood cancer, and to promoting resilience and well-being of pediatric oncology patients and their families.

Role of NOS3 DNA variants in externalizing behavioral problems observed in childhood leukemia survivors

OBJECTIVE

Neuropsychological problems occurrence varies among childhood cancer survivors, and associated risk factors have not been fully deciphered. We wanted to study the role of genetic variants in behavioral problems in this population.

STUDY DESIGN

Behavioral problems in pediatric acute lymphoblastic leukemia patients (n=138) were investigated longitudinally, using the Child Behavior Checklist questionnaire and multilevel statistical modeling. Thirty-four candidate polymorphisms, related to anticancer drug effects, were investigated.

RESULTS

NOS3 gene functional polymorphisms showed significant association: patients homozygous for the minor allele at investigated loci showed decreased externalizing behavioral problems scores over time (t tests: T-786C n=69, P=0.003; G894T n=71, P=0.065). The effect was even more pronounced for individuals that are homozygous for the -786C844T haplotype (t test, n=69, P<0.001) and results were supported by multilevel modeling analyses (P<0.001). No such association was observed for internalizing behavioral problems.

CONCLUSION

NOS3 variants modulate externalizing problems individual trajectories, likely in relationship with glucocorticoid exposure.