Neurocognitive and neuroradiologic central nervous system late effects in children treated on Pediatric Oncology Group (POG) P9605 (standard risk) and P9201 (lesser risk) acute lymphoblastic leukemia protocols (ACCL0131): a methotrexate consequence? A report from the Children's Oncology Group

Episodes of acute methotrexate-related neurotoxicity linked to compromised long-term neurocognitive function

Methotrexate is a critical component of curative chemotherapy for pediatric acute lymphoblastic leukemia (ALL), but is associated with neurotoxicity. Information on long-term outcomes following an acute neurotoxic event is limited. Therefore, this report compares neurocognitive performance more than 12 months post diagnosis (mean = 4 years) between ALL patients with (n = 25) and without (n = 146) a history of acute neurotoxicity. Compared to children with no documented on-treatment neurotoxic event, children who experienced a neurotoxic event during treatment exhibited poorer performance on measures of fine motor function (p = .02) and attention (p = .02). Children with ALL who experience acute neurotoxicity may be candidates for early neuropsychological screening and intervention.

High-throughput sequencing of archival cerebrospinal fluid specimens defines B-lymphoblastic leukemia clonal composition

Detailed characterization of the B-lymphoblastic leukemia (B-ALL) cells which invade the central nervous system (CNS) has been limited by practical challenges. To test whether the clonal composition of the cerebrospinal fluid (CSF) reflects the primary B-ALL tissue, we applied immunoglobulin (Ig) high-throughput sequencing (HTS) of archival CSF cytospin preparations from six patients with morphologically defined CNS involvement. We discovered that most CSF clones are detectable at some timepoint in the primary tissue, but that shifting clonal abundance is prevalent across tissue sites between diagnosis and relapse. Ig HTS of CSF cytospins may improve understanding of sanctuary site dissemination in B-ALL.

Effect of two additional doses of intrathecal methotrexate during induction therapy on serious infectious toxicity in pediatric patients with acute lymphoblastic leukemia

Although initial central nervous system (CNS) involvement is rarely detected in childhood acute lymphoblastic leukemia (ALL), risk-adapted CNS-directed therapy is essential for all patients. Treatment intensity depends on the initial CNS status. In the AIEOP-BFM ALL 2009 trial, patients with cytomorphologic detection of leukemic blasts in initial cerebrospinal fluid were classified as CNS2 or CNS3 and received five intrathecal doses of methotrexate (MTX) in induction therapy compared to patients with CNS1 status (no blasts detected) who received three doses. The impact of additional intrathecal (IT) MTX on systemic toxicity in induction therapy is unknown. Between June 1st 2010 and February 28th 2017, a total of 6,136 ALL patients aged 1-17 years were enrolled onto the AIEOP-BFM ALL 2009 trial. The effect of three versus five doses of IT MTX during induction therapy on the incidence of severe infectious complications was analyzed. Among 4,706 patients treated with three IT MTX doses, 77 (1.6%) had a life-threatening infection during induction as compared to 59 of 1,350 (4.4%) patients treated with five doses (P<0.001; Odds Ratio 2.86 [95% Confidence Interval 1.99-4.13]). In a multivariate regression model, treatment with additional IT MTX proved to be the strongest risk factor for life-threatening infections (Odds Ratio 2.85 [1.96-4.14]). Fatal infections occurred in 16 (0.3%) and 38 (1.6%) patients treated with three or five IT MTX doses, respectively (P<0.001). As the relevance of additional intrathecal MTX in induction for relapse prevention in CNS2 patients is unclear, doses of intrathecal therapy have been reduced for these patients. (Clinicaltrials.gov identifiers: NCT01117441 and NCT00613457).

Utilization and Cost of Outpatient Rehabilitation Services for Pediatric Patients Treated for Acute Lymphoblastic Leukemia Using a Commercial Claims Database

OBJECTIVE

To investigate the temporal trends and factors associated with outpatient rehabilitation utilization and costs for pediatric acute lymphoblastic leukemia (ALL).

DESIGN

Deidentified administrative claims data and longitudinal health information on patients representing a mixture of ages, ethnicities, and geographic regions across the United States were accessed using Optum Labs Data Warehouse. Regression models were constructed to assess associations of outpatient rehabilitation with age, sex, race and ethnicity, year of diagnosis, and region.

SETTING

Outpatient rehabilitation.

PARTICIPANTS

1000 Patients aged 1-30 years with a new diagnosis of ALL between 1993 and 2017 and continuous insurance coverage (N=1000).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Outpatient rehabilitation service utilization and cost based on reimbursed charge codes, summarized over 36 months after cancer diagnosis.

RESULTS

In 1000 patients, utilization of outpatient rehabilitation services increased from 20% in 1993-2002 to 55% in 2013-2017. In the earliest era examined, physical and/or occupational therapy was provided to 18% and increased to 54% in the latest years. Speech service utilization remained between 5%-8% across timepoints. Inflation-adjusted cost for provision of services did not change significantly across time and remained low, accounting for a median of 1.3% (Q1, Q3 0.3, 3.4) of total treatment cost in 1993-2002 and decreasing to a median 0.4% (Q1, Q3, 0.1, 1.0) in 2013-2017. Age 1 to 5 years at ALL diagnosis was associated with increased rehabilitation visit number and cost, and treatment in the Midwest was associated with increased likelihood of outpatient rehabilitation service utilization compared to other geographic regions.

CONCLUSIONS

Outpatient rehabilitation services are being increasingly provided to patients with ALL at a relatively low cost per patient, yet geographic variability in care utilization is evident. These services do not add excessively to the overall cost of leukemia care and thus cost containment should not be an excuse to limit access.

Neurocognitive outcomes in adult survivors of neuroblastoma: A report from the Childhood Cancer Survivor Study

BACKGROUND

Despite survival improvements, there is a paucity of data on neurocognitive outcomes in neuroblastoma survivors. This study addresses this literature gap.

METHODS

Neurocognitive impairments in survivors were compared to sibling controls from the Childhood Cancer Survivor Study (CCSS) using the CCSS Neurocognitive Questionnaire. Impaired emotional regulation, organization, task efficiency, and memory defined as scores ≥90th percentile of sibling norms. Modified Poisson regression models evaluated associations with treatment exposures, era of diagnosis, and chronic conditions. Analyses were stratified by age at diagnosis (≤1 and >1 year) as proxy for lower versus higher risk disease.

RESULTS

Survivors (N = 837; median [range] age, 25 [17-58] years, age diagnosed, 1 [0-21] years) were compared to sibling controls (N = 728; age, 32 [16-43] years). Survivors had higher risk of impaired task efficiency (≤1 year relative risk [RR], 1.48; 95% confidence interval [CI], 1.08-2.03; >1 year RR, 1.58; 95% CI, 1.22-2.06) and emotional regulation (≤1 year RR, 1.51; 95% CI, 1.07-2.12; >1 year RR, 1.44; 95% CI, 1.06-1.95). Impaired task efficiency associated with platinum exposure (≤1 year RR, 1.74; 95% CI, 1.01-2.97), hearing loss (≤1 year RR, 1.95; 95% CI, 1.26-3.00; >1 year RR, 1.56; 95% CI, 1.09-2.24), cardiovascular (≤1 year RR, 1.83; 95% CI, 1.15-2.89; >1 year RR, 1.74; 95% CI, 1.12-2.69), neurologic (≤1 year RR, 2.00; 95% CI, 1.32-3.03; >1 year RR, 2.29; 95% CI, 1.64-3.21), and respiratory (>1 year RR, 2.35; 95% CI, 1.60-3.45) conditions. Survivors ≤1 year; female sex (RR, 1.54; 95% CI, 1.02-2.33), cardiovascular (RR, 1.71; 95% CI, 1.08-2.70) and respiratory (RR, 1.99; 95% CI, 1.14-3.49) conditions associated impaired emotional regulation. Survivors were less likely to be employed full-time (p < .0001), graduate college (p = .035), and live independently (p < .0001).

CONCLUSIONS

Neuroblastoma survivors report neurocognitive impairment impacting adult milestones. Identified health conditions and treatment exposures can be targeted to improve outcomes.

PLAIN LANGUAGE SUMMARY

Survival rates continue to improve in patients with neuroblastoma. There is a lack of information regarding neurocognitive outcomes in neuroblastoma survivors; most studies examined survivors of leukemia or brain tumors. In this study, 837 adult survivors of childhood neuroblastoma were compared to siblings from the Childhood Cancer Survivorship Study. Survivors had a 50% higher risk of impairment with attention/processing speed (task efficiency) and emotional reactivity/frustration tolerance (emotional regulation). Survivors were less likely to reach adult milestones such as living independently. Survivors with chronic health conditions are at a higher risk of impairment. Early identification and aggressive management of chronic conditions may help mitigate the level of impairment.

CXCR4 antagonists disrupt leukaemia-meningeal cell adhesion and attenuate chemoresistance

The effective prophylaxis and treatment of central nervous system (CNS) involvement in acute lymphoblastic leukaemia (ALL) remains a significant clinical challenge. Developing novel and more effective CNS-directed therapies has been hampered, in part, by our limited understanding of the leukaemia niche in the CNS relative to the bone marrow. Accordingly, defining the molecular and cellular components critical for the establishment and maintenance of the CNS leukaemia niche may lead to new therapeutic opportunities. In prior work we showed that direct intercellular interactions between leukaemia and meningeal cells enhance leukaemia chemoresistance in the CNS. Herein, we show that the CXCR4/CXCL12 chemokine axis contributes to leukaemia-meningeal cell adhesion. Importantly, clinically tested CXCR4 antagonists, which are likely to cross the blood-brain and blood-cerebral spinal fluid barriers and penetrate the CNS, effectively disrupted leukaemia-meningeal cell adhesion. Moreover, by disrupting these intercellular interactions, CXCR4 antagonists attenuated leukaemia chemoresistance in leukaemia-meningeal cell co-culture experiments and enhanced the efficacy of cytarabine in targeting leukaemia cells in the meninges in vivo. This work identifies the CXCR4/CXCL12 axis as an important regulator of intercellular interactions within the CNS leukaemia niche and supports further testing of the therapeutic efficacy of CXCR4 antagonists in overcoming CNS niche-mediated chemoresistance.

Feasibility of serial neurocognitive assessment using Cogstate during and after therapy for childhood leukemia

PURPOSE

Neurocognitive impairment is frequently observed among survivors of childhood acute lymphoblastic leukemia (ALL) within the domains of attention, working memory, processing speed, executive functioning, and learning and memory. However, few studies have characterized the trajectory of treatment-induced changes in neurocognitive function beginning in the first months of treatment, to test whether early changes predict impairment among survivors. If correct, we hypothesize that those children who are most susceptible to early impairment would be ideal subjects for clinical trials testing interventions designed to protect against treatment-related neurocognitive decline.

METHODS

In this pilot study, we prospectively assessed neurocognitive functioning (attention, working memory, executive function, visual learning, and processing speed), using the Cogstate computerized battery at six time points during the 2 years of chemotherapy treatment and 1-year post-treatment (Dana-Farber Cancer Institute ALL Consortium protocol 11-001; NCT01574274).

RESULTS

Forty-three patients with ALL consented to serial neurocognitive testing. Of the 31 participants who remained on study through the final time point, 1 year after completion of chemotherapy, 28 (90%) completed at least five of six planned Cogstate testing time points. Performance and completion checks indicated a high tolerability (≥ 88%) for all subtests. One year after completion of treatment, 10 of 29 patients (34%) exhibited neurocognitive function more than 2 standard deviations below age-matched norms on one or more Cogstate subtests.

CONCLUSIONS

Serial collection of neurocognitive data (within a month of diagnosis with ALL, during therapy, and 1-year post-treatment) is feasible and can be informative for evaluating treatment-related neurocognitive impairment.

A Comprehensive Review of Neuropsychologic Studies Supports the Concept That Adequate Folinic Acid Rescue Prevents Post Methotrexate Neurotoxicity

PURPOSE

To review all studies providing evidence of the correlation between folinic acid (FA) rescue inadequacy and long-term cognitive damage in neuropsychological studies of children with acute lymphoblastic leukemia or osteogenic sarcoma treated under protocols using high-dose methotrexate and FA rescue.

METHODS

A comprehensive literature search was performed of all databases of the Web of Science Citation Index, during 1990-2020, for the terms: neuropsychological, neurocognitive, and cognitive, together with acute lymphoblastic (and lymphocytic) leukemia and osteogenic sarcoma. English-language peer-reviewed articles on neuropsychological assessments of children who had been treated with high-dose methotrexate without irradiation, and which included details of methotrexate and FA schedules, were selected. In addition, a personal database of over 500 reprints of articles from over 130 journals was reviewed on the subjects of methotrexate and FA and their side effects.

RESULTS

Three groups of studies were found and analyzed, with (1) no evidence of cognitive deterioration, (2) evidence of cognitive deterioration, and (3) more than 1 protocol grouped together, preventing separate analysis of any protocols, Protocols without cognitive deterioration reported adequate FA rescue, and those with cognitive deterioration reported inadequate FA rescue.

CONCLUSION

Neuropsychological evaluation supported inadequate FA being the cause of neurocognitive damage after high-dose methotrexate and that adequate FA rescue prevents this complication.

Comparison of Neurocognitive Functioning and Fine Motor Skills in Pediatric Cancer Survivors and Healthy Children

Background: The late treatment outcomes of pediatric brain tumors and of hematopoietic and lymphoid tissue tumors are an important focus of both rehabilitation and research. Neurocognitive and motor disorders induce further learning problems impeding social-emotional adaptation throughout a whole lifespan. Core deficits in short-term and working memory, visuospatial constructional ability, verbal fluency, and fine motor skills underlie distorted intellectual and academic achievement. This study aimed to assess the individual differences in cognitive ability and fine motor skills of pediatric tumor survivors and the age-matched healthy controls. Methods: A total of 504 tumor survivors after treatment and 646 age-matched healthy controls underwent neurocognitive and fine motor assessments. Findings: The group of tumor survivors scored significantly worse in both neurocognitive and fine motor skill in compared with the healthy control group. The pediatric brain tumor survivors (PBT group) performed worse in cognitive (p < 0.001 for verbal fluency and p < 0.001 for visuospatial constructional ability) and motor tests (p < 0.001) compared to the healthy controls. Hematopoietic and Lymphoid Tissues tumors survivors (THL group) performed worse in verbal fluency (p < 0.01) and visuospatial constructional test (p < 0.001) compared to the control group. Furthermore, the PBT group had worse results in visuospatial constructional ability (p < 0.05) and fine motor (p < 0.001) ability than the THL group. Significant differences between females and males were found in fine motor test performance in the PBT group (p < 0.05), as well as in verbal fluency (p < 0.01) and visuospatial constructional ability (p < 0.01) in the control group. Neurocognitive and fine motor skill characteristics in the THL group did not correlate with age.

Proton Beam Therapy for Pediatric Tumors of the Central Nervous System-Experiences of Clinical Outcome and Feasibility from the KiProReg Study

As radiotherapy is an important part of the treatment in a variety of pediatric tumors of the central nervous system (CNS), proton beam therapy (PBT) plays an evolving role due to its potential benefits attributable to the unique dose distribution, with the possibility to deliver high doses to the target volume while sparing surrounding tissue. Children receiving PBT for an intracranial tumor between August 2013 and October 2017 were enrolled in the prospective registry study KiProReg. Patient's clinical data including treatment, outcome, and follow-up were analyzed using descriptive statistics, Kaplan-Meier, and Cox regression analysis. Adverse events were scored according to the Common Terminology Criteria for Adverse Events (CTCAE) 4.0 before, during, and after PBT. Written reports of follow-up imaging were screened for newly emerged evidence of imaging changes, according to a list of predefined keywords for the first 14 months after PBT. Two hundred and ninety-four patients were enrolled in this study. The 3-year overall survival of the whole cohort was 82.7%, 3-year progression-free survival was 67.3%, and 3-year local control was 79.5%. Seventeen patients developed grade 3 adverse events of the CNS during long-term follow-up (new adverse event n = 7; deterioration n = 10). Two patients developed vision loss (CTCAE 4°). This analysis demonstrates good general outcomes after PBT.

Cranial MRI in Childhood Acute Leukemia during Treatment and Follow-Up Including the Impact of Intrathecal MTX-A Single-Center Study and Review of the Literature

Due to high survival rates, long-term sequelae, especially neurotoxicity, need to be considered in childhood acute leukemias. In this retrospective analysis of morphologic changes of the brain in children treated for acute leukemias, we included 94 patients (77 ALL, 17 AML; 51 male, 43 female; median age: 5 years) from a single center. We analyzed 170 cranial MRI scans (T2, FLAIR axial) for morphologic alterations of the brain and variations of the ventricular width (GDAH). In addition, the corresponding literature was reviewed. More than 50% of all patients showed cerebral pathomorphologies (CP). They were seen more often in children with ALL (55.8%), ≤ 6 years of age (60.8%), in relapse (58.8%) or after CNS irradiation (75.0%) and included white matter changes, brain atrophy, sinus vein thrombosis and ischemic events. GDAH significantly enlarged mainly in children up to 6 years, with relapse, high-risk leukemias or ALL patients. However, GDAH can normalize again. The number of intrathecal Methotrexate applications (≤12 vs. >12) showed no correlation to morphologic alterations besides a significant increase in GDAH (−0.3 vs. 0.9 mm) between the first and last follow-up MRI in ALL patients receiving >12 ith. MTX applications. The role of ith. MTX on CP needs to be further investigated and correlated to the neurocognitive outcome of children with acute leukemias.

Funcionalidade de Crianças com Leucemia em Tratamento Quimioterápico

Introdução: A leucemia e o tipo de neoplasia mais comumente diagnosticada em crianças no mundo, afetando-as em um período crítico do desenvolvimento neuropsicomotor. Estando diagnosticadas com uma doença ameaçadora da vida, essas crianças necessitam, concomitantemente aos cuidados curativos, de cuidados paliativos. Objetivo: Avaliar a funcionalidade de crianças com leucemia durante o tratamento quimioterápico e compara-la no início e depois de um ano de tratamento em curso. Método: Estudo de corte transversal, do tipo observacional analítico, com 37 crianças avaliadas por meio de entrevista com os pais, utilizando um formulário de pesquisa e o Inventario de Avaliação Pediátrica de Incapacidade (PEDI). A análise estatística foi realizada pelos testes t de Student e de Mann-Whitney. Resultados: Não foram encontradas diferenças estatisticamente significantes entre a funcionalidade de crianças no início e depois de um ano de tratamento, estando todas com a funcionalidade abaixo do esperado para a faixa etária. Conclusão: Como forma de evitar possíveis atrasos e/ou déficits irreversíveis no desenvolvimento dessas crianças, sugere-se a criação de um programa de reabilitação em cuidados paliativos nos serviços especializados para cuidar desse público desde o diagnóstico.

Cognitive impairment persists at least 1 year after juvenile rats are treated with methotrexate

Methotrexate (MTX) is widely employed for children with cancer, but is also associated with persistent cognitive deficits among survivors. The present study investigated the mechanisms behind long-term cognitive dysfunction after juvenile animals are treated with MTX. Male and female Long-Evans rats were treated with a combination of 6 systemic doses (0.5 mg/kg/dose intraperitoneally) and 4 intrathecal doses (1 mg/kg) beginning at post-natal age 3 weeks, a schedule designed to mimic repeated exposure given to children with leukemia. Behavioral testing was conducted at 60-61 weeks of age, followed by analysis of brain histolopathology. This MTX regimen had no acute toxicity and no effect on growth. The spatial memory and visual memory deficits observed at 13 and 17 weeks of age persisted 1 year after MTX exposure in both females and males. Significantly decreased cell proliferation and increased hippocampal microglial activation were observed in MTX-treated females when compared to the controls, with a similar trend in the male groups. In addition, MTX treatment significantly increased the number of TUNEL positive cells in the periventricular area. Our study demonstrates that a clinically relevant regimen of systemic and intrathecal MTX induces persistent deficits in cognition, lasting approximately 1 year after the last injection. The mechanisms behind MTX-induced deficits are likely multifactorial, including suppression of neurogenesis, microglial activation, and increased brain cell apoptosis. Our study suggests female and male animals differ in susceptibility to MTX-induced neurotoxicity and provides insights for developing therapeutic approaches to prevent treatment related cognitive impairment among children with ALL.

Feasibility of Cognitive Training to Promote Recovery in Cancer-Related Cognitive Impairment in Adolescent and Young Adult Patients

Background: Computer-based cognitive rehabilitation programs may help adolescent and young adult (AYA) patients with cancer-related cognitive impairment. This pilot study investigated the feasibility of cognitive rehabilitation as a preventive intervention for AYA patients receiving chemotherapy. Explorative objectives included the correlation of cognitive performance with serum brain-derived neurotrophic factor (BDNF). Methods: This pilot prospective study included English-speaking patients 12-25 years of age with a fist diagnosis of cancer requiring chemotherapy. Participants enrolled in the intervention arm participated in a computer-based neurocognitive training program for 20-30 minutes daily for 16 weeks. Outcome measures, including engagement with and completion of computerized neurocognitive testing and serum BDNF levels, were obtained within the first month following diagnosis, ∼16 and 24 weeks from enrollment. Results: Fourteen of 18 eligible patients provided consent, with 7 patients assigned to each the intervention arm and nonintervention arm. Seventy-one percent of the patients in the intervention arm completed at least 80% of the required activities. Compared to baseline, patients in the nonintervention arm demonstrated higher prevalence of impairment in four of the six cognitive domains (processing speed, visual attention, attention/working memory, and executive function) at the end of the study period. There was a nonstatistically significant reduction of serum BDNF levels over time, which was observed in both intervention and nonintervention arms. Conclusion: This pilot study provides some evidence that it is feasible for AYAs with new cancer diagnoses to receive standardized cognitive rehabilitation. Patients receiving cognitive activities experienced less impairment in numerous cognitive domains.

Structural and Functional Brain Imaging in Long-Term Survivors of Childhood Acute Lymphoblastic Leukemia Treated With Chemotherapy: A Systematic Review

Background

The effect of chemotherapy on brain development in long-term survivors of pediatric acute lymphoblastic leukemia (ALL) was systematically reviewed.

Methods

A systematic search of Pubmed, Scopus, and PsycINFO databases was conducted to identify articles published between January 2000 and February 2020 that implemented magnetic resonance imaging to assess brain structure and function in pediatric ALL survivors (diagnosed younger than 21 years of age). The review included articles that were published on children diagnosed with ALL between 0 and 21 years of age and treated with chemotherapy-only protocols. Articles meeting the inclusion criteria described survivors on average of 5 years or more from diagnosis and were peer-reviewed articles and original studies.

Results

The search yielded 1975 articles with 23 articles meeting inclusion criteria. The review revealed that survivors had statistically significant alterations in brain anatomy, most commonly a smaller hippocampus and impaired microstructural white matter integrity in frontal brain regions. Survivors also had impaired brain function including lower brain network efficiency and altered resting state connectivity. Survivors also displayed widespread reductions in brain activation (ie, frontal, temporal, parietal brain regions) during cognitive tasks.

Conclusion

Although the neurotoxic effects of cancer treatment are reduced in the absence of cranial radiation, survivors treated on chemotherapy-only protocols still display long-term alterations in brain structure and function, which contribute to lifelong neurocognitive late effects.

[Intellectual disability and cancer in children: An analysis of the decision-making process]

AIM

The aim was to describe and to analyze the ethics of decision-making in situations involving children with intellectual disability and cancer, from the referent-doctor's point-of-view, in pediatric oncology units in France.

METHODS

Pediatricians working in pediatric oncology units were interviewed through an online questionnaire and a semi-directive interview was systematically proposed. We analyzed the ethical issues that arose during the process of decision-making and we made suggestions in order to address them.

RESULTS

Sixteen doctors reported twenty-one clinical cases. Of these cases, one third of the children had a change in their oncologic treatment, with a risk of pejorative outcome on the prognosis. Despite the fact that ethical issues appeared in 80 % of the cases, there were few consultations with ethical committees. Decision-making process showed no difference compared to children without intellectual disability, thus raising ethical issues in the medical team. Our study showed discrepancy between frequently reported ethical issues, high consensus rate regarding treatment decision and lack of consultation with ethical committees.

DISCUSSION

We propose three steps to guide the decision-making process in situations involving children with intellectual disability and cancer: 1/deeper understanding of the child through reinforced interactions with their caregivers, 2/better cross-boundary discussions, to improve the effectiveness of the multidisciplinary staff, and 3/more systematic ethical committees consultation.

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.

Feasibility of Proton Beam Therapy for Infants with Brain Tumours: Experiences from the Prospective KiProReg Registry Study

AIMS

Proton beam therapy (PBT) has increasingly been applied for the treatment of young children when radiotherapy is needed. The treatment requires intensive multimodality care and is logistically demanding. In this analysis, we evaluated our experiences in treating infants with tumours of the central nervous system with PBT.

MATERIALS AND METHODS

Children younger than 2 years of age treated with PBT for central nervous system tumours enrolled in the prospective registry study KiProReg were retrospectively analysed. Information on patient characteristics, treatment, toxicities and outcome were evaluated. Adverse events were classified according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE V4.0) before, during and after PBT.

RESULTS

Between September 2013 and June 2018, 51 infants were eligible. The median age was 19 months (range 11-23 months) at the time of PBT. Tumour entities were ependymoma (51.0%), atypical teratoid rhabdoid tumour (39.0%), high-grade glioma (6.0%), pineoblastoma (2.0%) and medulloblastoma (2.0%). The prescribed median total dose was 54.0 Gy (range 45.0-59.4 Gy). Most received local radiotherapy. In four patients, craniospinal irradiation followed by a boost to the local tumour bed was applied. The median follow-up time was 42.0 months (range 7.3-86.2 months). The estimated 3-year local control, progression-free survival and overall survival rates for all patients were 62.7, 47.1 and 76.5%, respectively. During radiotherapy, 24 events of higher-grade (CTCAE ≥ °III) toxicities were reported. Interruption of radiotherapy for more than 2 days was due to infection (n = 3) or shunt complication (n = 2). Unexpected hospitalisation during radiotherapy affected 12 patients. Late adverse events attributable to radiotherapy included endocrinopathy (CTCAE °II; 7.8%), new onset of hearing loss (CTCAE °III; 5.8%) and visual impairment (CTCAE °IV; 1.9%). Transient radiation-induced imaging changes occurred in five patients (9.8%).

CONCLUSIONS

Our study indicates that PBT is feasible for very young children with central nervous system tumours, at least in the short term. However, it requires challenging interdisciplinary medical care and high logistical effort. For evaluation of late effects, longer follow-up and evaluation of neurocognitive outcome are desirable. More data have to be gathered to further define the role of radiotherapy in infants over time.

Characterization of Leukoencephalopathy and Association With Later Neurocognitive Performance in Pediatric Acute Lymphoblastic Leukemia

OBJECTIVES

The most common form of pediatric cancer is acute lymphoblastic leukemia (ALL). Magnetic resonance (MR) neuroimaging studies have revealed leukoencephalopathy (LE) in pediatric ALL, but the impact of LE on long-term neurocognitive performance remains unknown. This study aims to objectively characterize the prevalence, extent, and intensity of LE, and their association with later neurocognitive performance.

MATERIALS AND METHODS

Pediatric patients (N = 377) treated for ALL without irradiation underwent MR neuroimaging at 4 time points throughout therapy (end of remission induction [MR1], end of consolidation [MR2], and week 31 [MR3] and week 120 [end therapy, MR4] of continuation treatment) and neurocognitive evaluations at the end of therapy and 2 years later. Generalized estimation equation models with logit link were developed to explore the association between LE prevalence and extent with time points throughout therapy, age at diagnosis (≤5 years or >5 years), treatment risk arm (low risk or standard/high risk), and sex. General linear models were also developed to investigate the association between neuroimaging metrics during treatment and neurocognitive performance at 2-year follow-up.

RESULTS

The prevalence of LE was greatest (22.8%, 74/324) after consolidation therapy. The prevalence of LE increased at MR2 relative to MR1 regardless of treatment risk arm (both P's < 0.001), age group (both P's < 0.001), or sex (male, P < 0.001; female, P = 0.013). The extent of white matter affected also increased at MR2 relative to MR1 regardless of treatment risk arm (standard/high risk, P < 0.001; low risk, P = 0.004), age group (both P's < 0.001), or sex (male, P < 0.001; female, P = 0.001). Quantitative relaxation rates were significantly longer in LE compared with that in normal-appearing white matter in the same examination (T1, P < 0.001; T2, P < 0.001). The LE prevalence early in therapy was associated with increased parent ratings of conduct problems (P = 0.039) and learning difficulties (P = 0.036) at 2-year follow-up compared with that at the end of therapy. A greater extent of LE early in therapy was associated with decreasing performance on a measure of processing speed (P = 0.003) from the end of therapy to 2-year follow-up. A larger extent of LE at the end of therapy was associated with decreased performance in reading (P = 0.004), spelling (P = 0.003), and mathematics (P = 0.019) at 2-year follow-up and increasing problems with attention (omissions, P = 0.045; β, P = 0.015) and memory (list A total recall, P = 0.010) at 2-year follow-up compared with that at the end of therapy.

CONCLUSIONS

In this large cohort of pediatric patients treated for ALL without irradiation, asymptomatic LE during therapy can be seen in almost a quarter of patients, involves as much as 10% of the white matter volume, and is associated with decreasing neurocognitive performance, increasing parent reports of conduct problems, and learning difficulties in survivors.

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.

Neurotoxicity of Cancer Therapies

PURPOSE OF REVIEW

This article reviews neurologic complications associated with chemotherapy, radiation therapy, antiangiogenic therapy, and immunotherapy.

RECENT FINDINGS

Cancer therapies can cause a wide range of neurologic adverse effects and may result in significant patient morbidity and mortality. Although some treatment-associated neurologic complications manifest acutely and are often reversible and transient, others occur with delayed onset, can be progressive, and are uniquely challenging to patient management. With an increase in multimodality and combination therapies, including targeted therapies and immunotherapies, and prolonged patient survival, novel and unique patterns of neurologic complications have emerged.

SUMMARY

Both conventional and novel cancer therapies can adversely affect the nervous system, thereby producing a wide range of neurologic complications. Increased awareness among neurologists and early recognition of cancer therapy-induced neurotoxic syndromes is critically important to minimize patient morbidity, prevent permanent injury, and improve patient outcomes.

Prevalence of leukoencephalopathy and its potential cognitive sequelae in cancer patients

Due to the rising use of chemotherapy treatment in cancer patients and growing survival rates, therapy-induced neurotoxic side effects are increasingly reported. Given the ambiguity about the prevalence and severity of leukoencephalopathy, one of such toxic side effects, in non-central nervous system (CNS) cancer patients, we performed a systematic literature search using the PubMed/Medline database to summarize existing literature regarding leukoencephalopathy epidemiology in non-CNS cancer patients and its potential cognitive sequelae. The search was based on the following terms: ('MRI' OR 'T2-weighted MRI' OR 'FLAIR') AND ('cancer' OR 'tumour' OR 'leukaemia' OR 'neoplasms') AND ('chemotherapy' OR 'radiotherapy') AND ('posterior reversible encephalopathy' OR 'leukoencephalopathy' OR 'cerebral ischaemia' OR 'stroke'). Thirty-two studies discussing the occurrence of leukoencephalopathy in cancer patients were included, of which the majority investigated Acute Lymphoblastic Leukaemia (ALL) patients (n = 22).Regularly scanned ALL patients showed a prevalence of leukoencephalopathy between 17 - 87%, and 15 - 83% of patients presented with leukoencephalopathy when only scanned after a CNS event. When diagnosed with posterior reversible encephalopathy syndrome, 100% of patients showed leukoencephalopathy because its diagnosis is based in part on observable lesions. An increased prevalence was observed in ALL patients treated with higher doses of methotrexate (5 g/m² MTX, 42 - 87%) when compared to lower doses (< 5 g/m², 32 - 67%). By contrast, in breast cancer patients, white matter lesions were mainly detected in case of neurological symptoms, but not (yet) clearly associated with chemotherapy administration. However, chemotherapy treatment was associated with more infratentorial microbleeds in breast cancer patients . Up to 50% of other (neurologically asymptomatic) solid tumour patients presented white matter lesions, even years after treatment. When cognitive data were investigated, lesioned patients showed lower scores on neurocognitive tests in 50% of studies, years after ending therapy.In conclusion, leukoencephalopathy is well-documented for ALL patients (with a focus on methotrexate), but there is a lack of knowledge for other intravenous chemotherapeutics, other oncological populations, wider age ranges and possible risk factors (e.g. history of CNS event). Furthermore, the long-term neuropsychological impact and potential risk for neurodegenerative processes due to leukoencephalopathy remains inconclusive. Hence, large international databanks, epidemiological and prospective case-control studies are necessary to stratify risk groups for CNS-related side effects.

Brain Activity Associated With Attention Deficits Following Chemotherapy for Childhood Acute Lymphoblastic Leukemia

BACKGROUND

The impact of contemporary chemotherapy treatment for childhood acute lymphoblastic leukemia on central nervous system activity is not fully appreciated.

METHODS

Neurocognitive testing and functional magnetic resonance imaging (fMRI) were obtained in 165 survivors five or more years postdiagnosis (average age = 14.4 years, 7.7 years from diagnosis, 51.5% males). Chemotherapy exposure was measured as serum concentration of methotrexate following high-dose intravenous injection. Neurocognitive testing included measures of attention and executive function. fMRI was obtained during completion of two tasks, the continuous performance task (CPT) and the attention network task (ANT). Image analysis was performed using Statistical Parametric Mapping software, with contrasts targeting sustained attention, alerting, orienting, and conflict. All statistical tests were two-sided.

RESULTS

Compared with population norms, survivors demonstrated impairment on number-letter switching (P < .001, a measure of cognitive flexibility), which was associated with treatment intensity (P = .048). Task performance during fMRI was associated with neurocognitive dysfunction across multiple tasks. Regional brain activation was lower in survivors diagnosed at younger ages for the CPT (bilateral parietal and temporal lobes) and the ANT (left parietal and right hippocampus). With higher serum methotrexate exposure, CPT activation decreased in the right temporal and bilateral frontal and parietal lobes, but ANT alerting activation increased in the ventral frontal, insula, caudate, and anterior cingulate.

CONCLUSIONS

Brain activation during attention and executive function tasks was associated with serum methotrexate exposure and age at diagnosis. These findings provide evidence for compromised and compensatory changes in regional brain function that may help clarify the neural substrates of cognitive deficits in acute lymphoblastic leukemia survivors.

Drug repurposing for targeting cyclic nucleotide transporters in acute leukemias - A missed opportunity

While current treatment regimens for acute leukemia can dramatically improve patient survival, there remains room for improvement. Due to its roles in cell differentiation, cell survival, and apoptotic signaling, modulation of the cyclic AMP (cAMP) pathway has provided a meaningful target in hematological malignancies. Several studies have demonstrated that gene expression profiles associated with increased pro-survival cAMP activity or downregulation of various pro-apoptotic factors associated with the cAMP pathway are apparent in acute leukemia patients. Previous work to increase leukemia cell intracellular cAMP focused on the use of cAMP analogs, stimulating cAMP production via transmembrane-associated adenylyl cyclases, or decreasing cAMP degradation by inhibiting phosphodiesterase activity. However, targeting cyclic nucleotide efflux by ATP-binding cassette (ABC) transporters represents an unexplored approach for modulation of intracellular cyclic nucleotide levels. Preliminary studies have shown that inhibition of cAMP efflux can stimulate leukemia cell differentiation, cell growth arrest, and apoptosis, indicating that targeting cAMP efflux may show promise for future therapeutic development. Furthermore, inhibition of cyclic nucleotide transporter activity may also contribute multiple anticancer benefits by reducing extracellular pro-survival signaling in malignant cells. Hence, several opportunities for drug repurposing may exist for targeting cyclic nucleotide transporters.

A Review of Chronic Leukoencephalopathy among Survivors of Childhood Cancer

Currently, there are an estimated 400,000 long-term survivors of childhood cancer in the United States. Chronic leukoencephalopathy is a potential devastating late effect that can manifest as a range of neurological and neurocognitive sequelae. Survivors of the acute lymphocytic leukemia, central nervous system tumors, and stem cell transplant have frequently been exposed to cranial radiation, systemic and intrathecal chemotherapy, which places them at risk of developing chronic leukoencephalopathy. Defining leukoencephalopathy and its neuroimaging characteristics, the population of survivors at risk, its long-term consequences, and identifying prevention and intervention strategies can potentially mitigate the morbidity of these survivors. Better understanding of those at risk of leukoencephalopathy and its symptoms can lead to an improved quality of life for these cancer survivors.

Childhood leukemia survivors exhibit deficiencies in sensory and cognitive processes, as reflected by event-related brain potentials after completion of curative chemotherapy: A preliminary investigation

Objective: The purpose of this study was to characterize post-chemotherapy sensory, memory, and attention abilities in childhood survivors of acute lymphoblastic leukemia (ALL) to better understand how treatment affects cognitive functioning. Methods: Eight ALL survivors and eight age-matched, healthy children between the ages of 5-11 years participated in the study. Among the ALL survivors, a median of 63 days (range 22-267 days) elapsed between completion of chemotherapy and this assessment. Sounds were presented in an oddball paradigm while recording the electroencephalogram in separate conditions of passive listening and active task performance. To assess different domains of cognition, we measured event-related brain potentials (ERPs) reflecting sensory processing (P1 component), working memory (mismatch negativity [MMN] component), attentional orienting (P3a), and target detection (P3b component) in response to the sounds. We also measured sound discrimination and response speed performance. Results: Relative to control subjects, ALL survivors had poorer performance on auditory tasks, as well as decreased amplitude of the P1, MMN, P3a, and P3b components. ALL survivors also did not exhibit the amplitude gain typically observed in the sensory P1 component when attending to the sound input compared to when passively listening. Conclusions: Atypical responses were observed in brain processes associated with sensory discrimination, auditory working memory, and attentional control in pediatric ALL survivors indicating deficiencies in all cognitive domains compared to age-matched controls. Significance: ERPs differentiated aspects of cognitive functioning, which may provide a useful tool for assessing recovery and risk of post-chemotherapy cognitive deficiencies in young children. The decreased MMN amplitude in ALL survivors may indicate (N-methyl D-aspartate) NMDA dysfunction induced by methotrexate, and thus provides a potential therapeutic target for chemotherapy-associated cognitive impairments.

Long-term leukoencephalopathy and neurocognitive functioning in childhood sarcoma patients treated with high-dose intravenous chemotherapy

PURPOSE

Knowledge is limited regarding the prevalence and persistence of chemotherapy-induced leukoencephalopathy in childhood sarcoma patients. This study explored the presence, clinical relevance, and potential risk factors of leukoencephalopathy in childhood bone and soft tissue sarcoma survivors, treated with intravenous chemotherapy.

METHODS

We acquired cross-sectional neurocognitive data in adult survivors (n = 34) (median age at diagnosis [AaD] = 13.32 years, age range = 16-35 years) and healthy age-matched controls (n = 34). Additionally, magnetic resonance imaging included T2-weighted FLAIR (leukoencephalopathy Fazekas rating), multiexponential T2 relaxation (MET2), and multishell diffusion MRI to estimate myelin integrity-related metrics and fluid movement restrictions. Finally, chemotherapy subgroups (methotrexate, alkylating agents, or combination), AaD, and Apoε and MTHFRC677T polymorphisms were explored as potential risk factors for leukoencephalopathy.

RESULTS

At the group level, quality of life, working memory, processing speed, and visual memory were significantly lower in patients compared to controls. Furthermore, long-term leukoencephalopathy was observed in 27.2% of the childhood sarcoma survivors, which was related to attentional processing speed. Lesions were related to diffusion-derived, but not to myelin-sensitive metrics. A significant interaction effect between AaD and chemotherapy group demonstrated more lesions in case of high-dose methotrexate (HD-MTX) (F = 3.434, P = .047). However, patients treated with alkylating agents (without HD-MTX) also showed lesions in younger patients. Genetic predictors were nonsignificant.

CONCLUSION AND IMPLICATION

This study suggests long-term leukoencephalopathy with possibly underlying changes in vasculature, inflammation, or axonal injury, but not necessarily long-term demyelination. Such lesions could affect processing speed, and as such long-term daily life functioning of these patients.

Interactions between visual working memory and visual attention among survivors of pediatric acute lymphoblastic leukemia (ALL) and their healthy peers

Introduction: There is increasing concern for adverse cognitive late effects among survivors of pediatric acute lymphoblastic leukemia (ALL) given the widespread impact they have on academic achievement, particularly working memory and attention. We assessed performance among survivors and their healthy peers on a dual task paradigm measuring visual working memory (VWM) and visual attention independently and the dynamic relationship between the two. Assessing specific subsets within cognitive domains allows for understanding the distinct nature of cognitive impairments. Method: Participants were 34 survivors of ALL who have been off-treatment and disease free for 7.5 years; and 20 healthy controls, all between the ages of 10 and 18 years. We utilized behavioral single- and dual-task paradigms. In the dual tasks, participants maintained several items in VWM while performing a visual attention task (Eriksen Flanker Task) that required processing of a target stimulus while inhibiting the processing of distractor stimuli. The single tasks involved performing only the VWM task or only the visual attention task. Results: Results revealed survivors of ALL performed significantly worse than their healthy peers on the single visual attention task but not the single VWM task. Of particular interest, group differences were obtained on the dual VWM and visual attention tasks, such that the VWM and attention tasks reciprocally interfered with each other only among survivors and not their healthy peers. Conclusions: Our results highlight a core deficit in visual attention that is exacerbated by VWM demands among survivors of ALL. The implementation of tasks from cognitive neuroscience paradigms may be sensitive to cognitive impairments experienced by cancer survivors. Assessment and intervention practices among survivors of pediatric ALL are discussed.

Brain morphology and information processing at the completion of chemotherapy-only treatment for pediatric acute lymphoblastic leukemia

Background: Approximately 50% of survivors of childhood acute lymphoblastic leukemia (ALL) demonstrate cognitive impairments. However, the trajectory of change and contributing neuropathology is unclear, limiting our ability to tailor intervention content and timing. This study aimed to explore information processing abilities and brain morphology early post-treatment for pediatric ALL. Procedure: Twenty-one children at the end of ALL treatment and 18 controls underwent neuropsychological assessment. A subset also completed structural magnetic resonance imaging. Results: A principal component analysis generated two cognitive factors: information processing capacity and information processing speed. Compared to control group, the ALL group displayed deficits in capacity, but not speed. No group differences were identified in morphology. No relationship was identified between capacity or speed and morphology. Conclusion: Early cognitive intervention should target information processing abilities using a system-wide approach. Future studies should employ alternative imaging techniques sensitive to white-matter microstructure when exploring pathology underlying information processing deficits.

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.

The Impact of Persistent Leukoencephalopathy on Brain White Matter Microstructure in Long-Term Survivors of Acute Lymphoblastic Leukemia Treated with Chemotherapy Only

BACKGROUND AND PURPOSE

Survivors of acute lymphoblastic leukemia are at risk for neurocognitive deficits and leukoencephalopathy. We performed a longitudinal assessment of leukoencephalopathy and its associations with long-term brain microstructural white matter integrity and neurocognitive outcomes in survivors of childhood acute lymphoblastic leukemia treated on a modern chemotherapy-only protocol.

MATERIALS AND METHODS

One hundred seventy-three survivors of acute lymphoblastic leukemia (49% female), treated on a chemotherapy-only protocol, underwent brain MR imaging during active therapy and repeat imaging and neurocognitive testing at follow-up (median, 13.5 years of age; interquartile range, 10.7-17.6 years; median time since diagnosis, 7.5 years; interquartile range, 6.3-9.1 years). Persistence of leukoencephalopathy was examined in relation to demographic and treatment data and to brain DTI in major fiber tracts and neurocognitive testing at follow-up.

RESULTS

Leukoencephalopathy was found in 52 of 173 long-term survivors (30.0%) and persisted in 41 of 52 (78.8%) who developed it during therapy. DTI parameters were associated with leukoencephalopathy in multiple brain regions, including the corona radiata (fractional anisotropy, P = .001; mean diffusivity, P < .001), superior longitudinal fasciculi (fractional anisotropy, P = .02; mean diffusivity, P < .001), and superior fronto-occipital fasciculi (fractional anisotropy, P = .006; mean diffusivity, P < .001). Mean diffusivity was associated with neurocognitive impairment including in the genu of the corpus callosum (P = .04), corona radiata (P = .02), and superior fronto-occipital fasciculi (P = .02).

CONCLUSIONS

Leukoencephalopathy during active therapy and neurocognitive impairment at long-term follow-up are associated with microstructural white matter integrity. DTI may be more sensitive than standard MR imaging for detection of clinically consequential white matter abnormalities in childhood acute lymphoblastic leukemia survivors treated with chemotherapy and in children undergoing treatment.

Neurodevelopmental consequences of pediatric cancer and its treatment: applying an early adversity framework to understanding cognitive, behavioral, and emotional outcomes

Today, children are surviving pediatric cancer at unprecedented rates, making it one of modern medicine's true success stories. However, we are increasingly becoming aware of several deleterious effects of cancer and the subsequent "cure" that extend beyond physical sequelae. Indeed, survivors of childhood cancer commonly report cognitive, emotional, and psychological difficulties, including attentional difficulties, anxiety, and posttraumatic stress symptoms (PTSS). Cognitive late- and long-term effects have been largely attributed to neurotoxic effects of cancer treatments (e.g., chemotherapy, cranial irradiation, surgery) on brain development. The role of childhood adversity in pediatric cancer - namely, the presence of a life-threatening disease and endurance of invasive medical procedures - has been largely ignored in the existing neuroscientific literature, despite compelling research by our group and others showing that exposure to more commonly studied adverse childhood experiences (i.e., domestic and community violence, physical, sexual, and emotional abuse) strongly imprints on neural development. While these adverse childhood experiences are different in many ways from the experience of childhood cancer (e.g., context, nature, source), they do share a common element of exposure to threat (i.e., threat to life or physical integrity). Therefore, we argue that the double hit of early threat and cancer treatments likely alters neural development, and ultimately, cognitive, behavioral, and emotional outcomes. In this paper, we (1) review the existing neuroimaging research on child, adolescent, and adult survivors of childhood cancer, (2) summarize gaps in our current understanding, (3) propose a novel neurobiological framework that characterizes childhood cancer as a type of childhood adversity, particularly a form of early threat, focusing on development of the hippocampus and the salience and emotion network (SEN), and (4) outline future directions for research.

Liposomal Cytarabine Induces Less Neurocognitive Dysfunction Than Intrathecal Methotrexate in an Animal Model

Liposomal cytarabine is currently being tested clinically as an alternative to intrathecal (IT) methotrexate (MTX) for preventing relapse within the central nervous system among patients with acute lymphoblastic leukemia. To compare the toxicity and cognitive deficits caused by IT MTX versus liposomal cytarabine, juvenile Long Evans rats were treated with IT injections of MTX 1 mg/kg×4 doses over 8 days, or liposomal cytarabine 0.8 mg once. Mean concentrations of free cytarabine in cerebrospinal fluid remained above the cytotoxic threshold of 0.4 μM for 2 weeks after dosing. Animals treated with liposomal cytarabine exhibited normal recognition and spatial memory 4 weeks after injection. In contrast, exposure to IT MTX led to impaired cognitive function. In addition, mean hematocrit on day 11 was significantly lower in the MTX-treated animals (30.8%; 95% confidence interval, 27.0%-34.7%; n=6) compared with that in the liposomal cytarabine-treated animals (39.5%; 95% confidence interval, 38.4%-40.6%; n=6; P<0.0001). Our data suggest that liposomal cytarabine induces fewer neurocognitive deficits and less acute hematologic toxicity compared with IT MTX. Liposomal cytarabine may therefore have therapeutic advantages over IT MTX, if it is equally effective in preventing relapse.

Neurocognitive Consequences of Childhood Leukemia and Its Treatment

As survival rates have improved in pediatric patients with leukemia, late side effects from chemotherapeutics and radiotherapy have become important considerations. We investigated these side effects and evaluated their impact on neurocognitive functions. The observational study included 68 patients with acute leukemia who were treated at Eskisehir Osmangazi University Medical Faculty. The study also included 62 of the patients' closest age siblings as a control group. Demographic and clinical data, chemotherapy protocol, use of radiotherapy were recorded, neurological and ophthalmological examinations, cranial imaging, electroencephalography, visual evoked potential, and hearing investigations were performed, and neurocognitive functions were evaluated. At least one or more late effects detected by a neurologic abnormality on physical exam, cranial magnetic resonance imaging, neurological tests, or neurocognitive tests was significantly more likely in the patient group (82.4%) compared to the control group (29%, p < 0.001). A higher rate (82.4%) of delayed neurological and cognitive problems occurred in children who received radiotherapy, intrathecal and/or systemic chemotherapy during leukemia treatment compared to age-matched siblings. Patients being treated for leukemia should be periodically evaluated for treatment-related side effects. Prophylactic interventions such cognitive training and maintenance of academic growth may offer the best hope of preventing late effects.

The State of Cellular Adoptive Immunotherapy for Neuroblastoma and Other Pediatric Solid Tumors

Research on adult cancer immunotherapy is proceeding at a rapid pace resulting in an impressive success rate exemplified by a few high profile cases. However, this momentum is not readily extended to pediatric immunotherapy, and it is not for lack of trying. Though reasons for the slower advance are not apparent, some issues can be raised. Pediatric cancer patients represent a distinct demographic group whose immune system is inherently different from that of mature adults. Treating pediatric patients with immunotherapy designed for adults may not yield objective clinical responses. Here, we will present an update on adoptive T-cell and natural killer-cell therapies for neuroblastoma and other childhood solid tumors. Additionally, we will delineate key differences between human fetal/neonatal and adult immune systems. We hope this will generate interests leading to the discussion of potential future directions for improving adoptive cancer immunotherapy for children.

Neurotoxicity after high-dose methotrexate (MTX) is adequately explained by insufficient folinic acid rescue

PURPOSE

To challenge the view that the dose of folinic acid rescue after high-dose methotrexate (MTX) has no significance in the prevention of neurotoxicity and to present the minority view that neurotoxicity can be prevented by an adequate dose of folinic acid, without compromising treatment results. Several fallacies that led to the misunderstanding of post MTX neurotoxicity are presented.

METHODS

Data mining using search engines was used to find relevant publications, and an e-mail survey of more than 60 authors of articles in this field was performed. All relevant articles identified were read in their entirety.

RESULTS

Examples of clinical studies with neurotoxicity following inadequate rescue are given. Some studies demonstrated no neurotoxicity when adequate doses of folinic acid rescue were started 24-36 h after the start of HDMTX rescue even after mega doses of MTX. Rescue started after 42 h was associated with neurotoxicity except in patients with low serum MTX levels after 24 and 36 h. ALL protocols with neurotoxicity, especially BFM-like protocols, are presented. Protocol is reported in which single protocol changes prevented neurotoxicity.

CONCLUSIONS

From the published data, when folinic acid rescue is given in a sufficiently high enough dose and is started 24-36 h after the beginning of the methotrexate exposure, and virtually all forms of post MTX neurotoxicity can be prevented without compromising therapeutic results.

Harnessing the Immunotherapy Revolution for the Treatment of Childhood Cancers

Cancer immunotherapies can be classified into agents that amplify natural immune responses (e.g., checkpoint inhibitors) versus synthetic immunotherapies designed to initiate new responses (e.g., monoclonal antibodies [mAbs], chimeric antigen receptors [CARs]). Checkpoint inhibitors mediate unprecedented benefit in some adult cancers, but have not demonstrated significant activity in pediatric cancers, likely due their paucity of neoantigens. In contrast, synthetic immunotherapies such as mAbs and CAR T cells demonstrate impressive effects against childhood cancers. Intense efforts are underway to enhance the effectiveness of pediatric cancer immunotherapies through improved engineering of synthetic immunotherapies and by combining these with agents designed to amplify immune responses.

The relationship between cognitive and neuroimaging outcomes in children treated for acute lymphoblastic leukemia with chemotherapy only: A systematic review

Cognitive late-effects have been identified in patients treated with chemotherapy-only protocols for childhood acute lymphoblastic leukemia (ALL), yet the underlying neuropathology is not well understood. This review synthesized recent findings from eight articles investigating the relationship between neurocognitive and neuroimaging outcomes for patients treated for ALL with chemotherapy-only protocols. Reported cognitive domains, imaging methods, and neuroanatomy examined were variable. Despite this, 62.5% (n = 5) of the reviewed studies found a significant relationship between cognitive and imaging outcomes. Greater understanding of the effects of treatment on neuroanatomy and cognitive outcomes is critical for proactively managing ALL cognitive late-effects. Research directions are suggested.

How to Treat Involvement of the Central Nervous System in Hemophagocytic Lymphohistiocytosis?

OPINION STATEMENT

Central nervous system (CNS)-hemophagocytic lymphohistiocytosis (HLH) is not a disease in itself, but it is part of a systemic immune response. The vast majority of patients with CNS-HLH also have systemic HLH and a large number of patients with primary and secondary HLH have CNS involvement. Reactivations within the CNS are frequent during the course of HLH treatment and may occur concomitant with or independent of systemic relapses. It is also important to consider primary HLH as an underlying cause of "unknown CNS inflammation" as these patients may present with only CNS disease. To initiate proper treatment, a correct diagnosis must be made. A careful review of the patient's history and a thorough neurological examination are essential. In addition to the blood tests required to make a diagnosis of HLH, a lumbar puncture with cerebrospinal fluid (CSF) analysis and magnetic resonance imaging (MRI) should always be done in all cases regardless of the presence or absence of neurological signs or symptom. Treatment options for CNS-HLH include, but are not limited to, those commonly used in systemic HLH, including corticosteroids, etoposide, cyclosporine A, alemtuzumab, and ATG. In addition, intrathecal treatment with methotrexate and corticosteroids has become a standard care and is likely to be beneficial. Therapy must be initiated without inappropriate delay to prevent late effects in HLH. An interesting novel approach is an anti-IFN-gamma antibody (NI-0501), which is currently being tested. Hematopoietic stem cell transplantation (HSCT) also represents an important CNS-HLH treatment; patients with primary HLH may benefit from immediate HSCT even if there is active disease at time of transplantation, though care should be taken to monitor CNS inflammation through HSCT and treat if needed. Since CNS-HLH is a condition leading to the most severe late effects of HLH, early expert consultation is recommended.

Systemic cisplatin exposure during infancy and adolescence causes impaired cognitive function in adulthood

Cancer survivors diagnosed during infancy and adolescence may be at risk for chemotherapy-related cognitive impairments (CRCI), however the effects of pediatric chemotherapy treatment on adulthood cognitive function are not well understood. Impairments in memory, attention and executive function affect 15-50% of childhood leukemia survivors related to methotrexate exposure. Systemic cisplatin is used to treat a variety of childhood and adult cancers, yet the risk and extent of cognitive impairment due to platinum-based chemotherapy in pediatric patients is unknown. Systemic cisplatin penetrates the CNS, induces hippocampal synaptic damage, and leads to neuronal and neural stem/progenitor cell (NSC) loss. Survivors of non-leukemic cancers may be at risk for significant cognitive impairment related to cisplatin-driven neurotoxicity. We sought to examine the long-term effects of systemic cisplatin administration on cognitive function when administered during infancy and adolescence in a rat model. We performed cognitive testing in adult rats exposed to systemic cisplatin during either infancy or adolescence. Rats treated as adolescents showed significantly poor retrieval of a novel object as compared to controls. Further, cisplatin-treated infants and adolescents showed poor contextual discrimination as compared to controls, and an impaired response to cued fear conditioning. Ultimately, systemic cisplatin exposure resulted in more profound impairments in cognitive function in rats treated during adolescence than in those treated during infancy. Further, exposure to cisplatin during adolescence affected both hippocampus and amygdala dependent cognitive function, suggesting a more global cognitive dysfunction at this age.

Influence of ADORA2A gene polymorphism on leukoencephalopathy risk in MTX-treated pediatric patients affected by hematological malignancies

BACKGROUND

Methotrexate (MTX) can lead to neurotoxicity and asymptomatic leukoencephalopathy. However, the mechanism of MTX-related leukoencephalopathy is obscure. MTX and its metabolites inhibit 5-aminoimidazole-4-carboxamide ribonucleotide formiltransferase (ATIC) and promote adenosine release. Recently, it has been reported that adenosine and its receptor are related to certain central nervous system diseases. We investigated whether adenosine pathway gene polymorphisms and clinical factors were related to MTX-related leukoencephalopathy in pediatric patients affected by hematological malignancies.

PROCEDURE

Fifty-six Japanese childhood acute lymphoblastic leukemia or lymphoma patients were investigated. Patients were evaluated by magnetic resonance imaging of the brain before maintenance therapy or stem cell transplantation. Gene polymorphisms within the adenosine pathway (ATIC, adenosine A2A receptor [ADORA2A]) and the MTX pathway (methylenetetrahydrofolate reductase [MTHFR] and ABCB1) were genotyped using TaqMan assays. Clinical data were collected by accessing the medical records. MTX-related leukoencephalopathy was evaluated by a pediatric neurologist.

RESULTS

Twenty-one (37%) of 56 patients developed MTX-related leukoencephalopathy. Four of 21 patients developed clinical neurotoxicity. The minor allele CC genotype of rs2298383 (ADORA2A) was associated with MTX-related leukoencephalopathy (P = 0.010, odds ratio = 5.81, 95% confidence interval 1.50-22.50). High cumulative dose of systemic MTX was associated with MTX-related leukoencephalopathy after adjusting for sex, ADORA2A polymorphism, and prolonged high MTX concentration (P = 0.042, odds ratio = 1.18, 95% confidence interval 1.01-1.37).

CONCLUSIONS

ADORA2A rs2298383 and high cumulative dose of systemic MTX administration were significantly associated with MTX-related leukoencephalopathy. Our results indicate that pharmacological intervention within the adenosine pathway may be both a treatment and preventative option for MTX-related leukoencephalopathy.

Leukoencephalopathy and long-term neurobehavioural, neurocognitive, and brain imaging outcomes in survivors of childhood acute lymphoblastic leukaemia treated with chemotherapy: a longitudinal analysis

BACKGROUND

Leukoencephalopathy is observed in some children undergoing chemotherapy for acute lymphoblastic leukaemia, although its effects on long-term outcomes is unknown. This study examines the associations between acute leukoencephalopathy and neurobehavioural, neurocognitive, and brain white matter imaging outcomes in long-term survivors of childhood acute lymphoblastic leukaemia treated with chemotherapy without cranial radiation.

METHODS

In this longitudinal analysis, we used data of children with acute lymphoblastic leukaemia at St Jude Children's Research Hospital (Memphis, TN, USA) who had been treated between June 1, 2000, and Oct 31, 2010. Eligible patients were diagnosed with non-B-cell acute lymphoblastic leukaemia, aged at least 8 years, and survivors with at least 5 years since their initial diagnosis. Brain MRIs obtained during active therapy were systematically coded for leukoencephalopathy using Common Terminology Criteria for Adverse Event version 4. At least 5 years after their diagnosis, survivors completed neurocognitive testing, another brain MRI, and their parents completed neurobehavioural ratings of their child (Behavior Rating Inventory of Executive Function [BRIEF]). Follow-up MRI included diffusion tensor imaging to assess white matter integrity, with indices of fractional anisotropy, axial diffusivity, and radial diffusivity from frontal lobes, parietal lobes, and in the frontostriatal tract. The neuroradiologist, who assessed abnormal MRIs, was masked to both group assignment of survivors and the neurobehavioural and neurocognitive outcomes. The primary outcomes were neurobehavioural function, assessed from completed BRIEF, and neurocognitive performance, measured by direct neurocognitive tests (Delis-Kaplan Executive Function System, Wechsler Intelligence Scale for Children-IV/Wechsler Adult Intelligence Scale-III, Rey-Osterrieth Complex Figure Test, and Lafayette Grooved Pegboard Test). This study had completed enrolment in October, 2014, and is registered as an observational study at ClinicalTrials.gov, number NCT01014195.

FINDINGS

Between Feb 18, 2010, and Oct 22, 2014, 210 (70%) of 301 eligible survivors participated in our study of whom 190 were evaluable, 162 had an MRI. 56 participants had quantitative brain imaging data and were included in evaluable population analyses. 51 (27%) of the 190 evaluable participants had acute leukoencephalopathy. Compared with population norms, survivors were reported to have more neurobehavioural problems with working memory, organisation, initiation, and planning (p<0·001 for all). Survivors had worse scores than the general population on direct measures of memory span, processing speed, and executive function (p<0·05 for all). Survivors with a history of acute leukoencephalopathy had more neurobehavioural problems than survivors with no history of leukoencephalopathy on organisation (adjusted T-score 56·2 [95% CI 53·3-59·1] vs 52·2 [50·4-53·9], p=0·020) and initiation (55·5 [52·7-58·3] vs 52·1 [50·4-53·8], p=0·045). Survivors with acute leukoencephalopathy also had reduced white matter integrity in the frontostriatal tract at follow-up: lower fractional anisotropy (p=0·069), higher axial diffusivity (p=0·020), and higher radial diffusivity (p=0·0077). A one-unit change in the radial diffusivity index corresponded with a 15·0 increase in raw score points on initiation, 30·3 on planning, and 28·0 on working memory (p<0·05 for all).

INTERPRETATION

Acute leukoencephalopathy during chemotherapy treatment, without cranial radiation, for childhood acute lymphoblastic leukaemia predicted higher risk for long-term neurobehavioural problems and reduced white matter integrity in frontal brain regions. Survivors of childhood acute lymphoblastic leukaemia might benefit from preventive cognitive or behavioural interventions, particularly those who develop acute leukoencephalopathy.

FUNDING

National Institute of Mental Health, National Cancer Institute, American Lebanese Syrian Associated Charities.