Central nervous system chemotoxicity during treatment of pediatric acute lymphoblastic leukemia/lymphoma

Methotrexate-induced subacute myelopathy: a serious but treatable complication

Subacute myelopathy is a rare but serious complication of methotrexate (MTX) that may cause paraplegia. Although its underlying mechanisms have not been fully elucidated, homocysteine is thought to play a role in the pathogenesis of this adverse effect. Herein, we report the case of a 34-years old female patient with diffuse large B-cell lymphoma who developed progressive paraplegia accompanied by dysfunctional bladder and bowel movements after treatment with a modified CODOX-M/IVAC regimen, including high-dose intravenous MTX and intrathecal (IT-) MTX. Neurological symptoms gradually improved to almost normal levels within 4.5 months of onset following treatment with a combination of S-adenosylmethionine, methionine, cyanocobalamin, and folate. During chemotherapy, including high-dose MTX and IT-MTX for hematological malignancies, MTX-induced subacute neuronal damage should be carefully evaluated, and appropriate treatment should be initiated as early as possible.

Disruption of the Corticospinal Tract in Patients with Acute Lymphoblastic Leukemia: A Case Series

Three patients who exhibited hemiplegic symptoms on conventional brain magnetic resonance imaging (MRI), during maintenance treatment for acute lymphoblastic leukemia, are reported. All patients exhibited unilateral motor weakness and poor hand function during chemotherapy. Conventional MRI revealed no definite abnormal lesions. However, in diffusion tensor tractography, the affected corticospinal tract on the contralateral side, consistently with clinical dysfunction, revealed disrupted integrity, decreased fractional anisotropy, and increased apparent diffusion coefficient compared to the results of the unaffected side or control participants. Control participants matched for age, sex, and duration from leukemia diagnosis, who underwent chemotherapy but had no motor impairments, exhibited preserved integrity of both corticospinal tracts. Diffusion tensor tractography can help evaluate patients with acute lymphoblastic leukemia and neurological dysfunction.

Etiology and Outcome of Seizures in Children during Induction Remission Chemotherapy for Acute Lymphoblastic Leukaemia

Seizure is one of the most frequent neurological complication and morbid phenomenon among children receiving chemotherapy for acute lymphoblastic leukemia. As overall survival of children with acute lymphoblastic leukemia is improving, now the challenge is to reduce treatment-related adverse effect. However, not much is known about the etiology and natural history of these seizure in our pediatric population. This is a single centered study conducted in the Department of Pediatric Hematology and Oncology, Bangabandhu Sheikh Mujib Medical University. This prospective observational study was conducted over a period of 1 year from May 2017 to April 2018. A total of 105 patients aged 1 year to 17.9 years newly diagnosed as acute lymphoblastic leukemia were the study population. This study showed that in five (33.3%) patients, the underlying cause was suspected intracranial hemorrhage and it was the most common cause. All these five patients had features of severe sepsis and upper motor neuron sign associated with severe thrombocytopenia. Among them three had coagulopathy. Three (20%) patients had CNS leukemic infiltration. Suspected meningitis was attributed as the possible cause of seizure in two (13.33%) patients. Other identifiable causes were brain abscess in one patient, multiple cerebral infarction in one patient, hypertensive encephalopathy in one patient, and vincristine-induced neurotoxicity in one patient. In one patient no identifiable cause was found. Among 15 patients with seizure five (33.3%) patients were improved and completed induction remission chemotherapy. Ten (66.7%) patients died. In this study, we found sepsis and coagulopathy as the major underlying cause of seizure. Outcome was found very dismal in patients who developed seizure.

Direct CNS administration of rituximab and epratuzumab in a pediatric patient with relapsed refractory CNS B-cell acute lymphoblastic leukemia

Relapsed central nervous system (CNS) leukemia presents a therapeutic challenge to pediatric oncologists. Systemic monoclonal antibody therapy has shown recent promise in patients with relapsed acute lymphoblastic leukemia, however its effect on CNS disease in this population is not well established. We describe a case of multiply relapsed and refractory CNS leukemia in an adolescent patient who responded to the intra-CNS delivery of rituximab (anti-CD20) and epratuzumab (anti-CD22) therapy, demonstrating the practical use and potential efficacy of a novel route of monoclonal antibody administration in difficult-to-treat CNS leukemia.

Integrin α6-Targeted Molecular Imaging of Central Nervous System Leukemia in Mice

Central nervous system leukemia (CNS-L) is caused by leukemic cells infiltrating into the meninges or brain parenchyma and remains the main reason for disease relapse. Currently, it is hard to detect CNS-L accurately by clinically available imaging models due to the relatively low amount of tumor cells, confined blood supply, and the inferior glucose metabolism intensity. Recently, integrin α6-laminin interactions have been identified to mediate CNS-L, which suggests that integrin α6 may be a promising molecular imaging target for the detection of CNS-L. The acute lymphoblastic leukemia (ALL) cell line NALM6 stabled and transfected with luciferase was used to establish the CNS-L mouse model. CNS-L-bearing mice were monitored and confirmed by bioluminescence imaging. Three of our previously developed integrin α6-targeted peptide-based molecular imaging agents, Cy5-S5 for near-infrared fluorescence (NIRF), Gd-S5 for magnetic resonance (MR), and ¹⁸F-S5 for positron emission tomography (PET) imaging, were employed for the molecular imaging of these CNS-L-bearing mice. Bioluminescence imaging showed a local intensive signal in the heads among CNS-L-bearing mice; meanwhile, Cy5-S5/NIRF imaging produced intensive fluorescence intensity in the same head regions. Moreover, Gd-S5/MR imaging generated superior MR signal enhancement at the site of meninges, which were located between the skull bone and brain parenchyma. Comparatively, MR imaging with the clinically available MR enhancer Gd-DTPA did not produce the distinguishable MR signal in the same head regions. Additionally, ¹⁸F-S5/PET imaging also generated focal radio-concentration at the same head regions, which generated nearly 5-times tumor-to-background ratio compared to the clinically available PET radiotracer ¹⁸F-FDG. Finally, pathological examination identified layer-displayed leukemic cells in the superficial part of the brain parenchyma tissue, and immunohistochemical staining confirmed the overexpression of the integrin α6 within the lesion. These findings suggest the potential application of these integrin α6-targeted molecular imaging agents for the accurate detection of CNS-L.

Targeted blockade of immune mechanisms inhibit B precursor acute lymphoblastic leukemia cell invasion of the central nervous system

Acute lymphoblastic leukemia (ALL) dissemination to the central nervous system (CNS) is a challenging clinical problem whose underlying mechanisms are poorly understood. Here, we show that primary human ALL samples injected into the femora of immunodeficient mice migrate to the skull and vertebral bone marrow and provoke bone lesions that enable passage into the subarachnoid space. Treatment of leukemia xenografted mice with a biologic antagonist of receptor activator of nuclear factor κB ligand (RANKL) blocks this entry route. In addition to erosion of cranial and vertebral bone, samples from individuals with B-ALL also penetrate the blood-cerebrospinal fluid barrier of recipient mice. Co-administration of C-X-C chemokine receptor 4 (CXCR4) and RANKL antagonists attenuate both identified routes of entry. Our findings suggest that targeted RANKL and CXCR4 pathway inhibitors could attenuate routes of leukemia blast CNS invasion and provide benefit for B-ALL-affected individuals.

Pharmacogenetics of the Central Nervous System-Toxicity and Relapse Affecting the CNS in Pediatric Acute Lymphoblastic Leukemia

Simple Summary

Despite recent improvements in cure rates, pediatric acute lymphoblastic leukemia (ALL) patients remain at risk to develop relapse disease or suffer from therapy-associated side effects. Over 5% of adverse events appear in the central nervous system (CNS) and can impact survival or quality of life of the patients. Inherited genetic variations are possible predictive factors for these adverse events. This retrospective study aimed to investigate if inherited genetic variations in genes encoding drug-metabolizing enzymes and drug transporters localized in the blood-brain barrier are predictive for CNS events. Our results suggest that certain ABCB1, ABCG2 and GSTP1 gene polymorphisms influence CNS toxicity and CNS relapse. A more effective drug-clearance could lead to less toxicity but contribute to a higher chance of relapse and vice versa. Genetic variants in ABCB1, ABCG2 or GSTP1 genes are promising candidates for personalized medicine.

Abstract

Despite improving cure rates in childhood acute lymphoblastic leukemia (ALL), therapeutic side effects and relapse are ongoing challenges. These can also affect the central nervous system (CNS). Our aim was to identify germline gene polymorphisms that influence the risk of CNS events. Sixty single nucleotide polymorphisms (SNPs) in 20 genes were genotyped in a Hungarian non-matched ALL cohort of 36 cases with chemotherapy related acute toxic encephalopathy (ATE) and 544 controls. Five significant SNPs were further analyzed in an extended Austrian-Czech-NOPHO cohort (n = 107 cases, n = 211 controls) but none of the associations could be validated. Overall populations including all nations’ matched cohorts for ATE (n = 426) with seizure subgroup (n = 133) and posterior reversible encephalopathy syndrome (PRES, n = 251) were analyzed, as well. We found that patients with ABCB1 rs1045642, rs1128503 or rs2032582 TT genotypes were more prone to have seizures but those with rs1045642 TT developed PRES less frequently. The same SNPs were also examined in relation to ALL relapse on a case-control matched cohort of 320 patients from all groups. Those with rs1128503 CC or rs2032582 GG genotypes showed higher incidence of CNS relapse. Our results suggest that blood-brain-barrier drug transporter gene-polymorphisms might have an inverse association with seizures and CNS relapse.

Influence of genetic variants in asparaginase pathway on the susceptibility to asparaginase-related toxicity and patients' outcome in childhood acute lymphoblastic leukemia

BACKGROUND

Asparaginase (ASNase) is a key component in the treatment protocols of childhood acute lymphoblastic leukemia (ALL). Asparagine synthetase (ASNS) and the basic region leucine zipper activating transcription factor 5 (ATF5) mediate the anti-leukemic effect of ASNase. Only a few reports studied the association between polymorphisms in these genes and treatment-related toxicity and response. Therefore, the current study aimed to investigate the association of ASNS and ATF5 polymorphisms with the susceptibility to ASNase-related toxicity and disease outcome in a population of childhood ALL Egyptian patients.

METHODS

In this study, 88 children with ALL were enrolled and genotyped for ASNS T629A and ATF5 C362T polymorphisms using allelic discrimination assay.

RESULTS

The studied polymorphisms did not associate with hypersensitivity or thrombosis, while the ATF5 C362T polymorphism was associated significantly with decreased ASNase-associated pancreatitis (AAP) risk under the dominant model. Patients carrying TT/CT genotypes of ATF5 C362T polymorphism had a significantly better overall survival (OS) and longer event-free survival (EFS) compared to patients with CC genotype. Multivariate analysis confirmed the independent prognostic value of the ATF5 C362T dominant model.

CONCLUSION

ATF5 362TT and CT genotypes were associated with decreased risk to develop AAP and better disease outcome demonstrating a low risk for events and superior survival.

Computed Tomography in Acute Severe Central Nervous System Complications in Children Treated for Cancer: Still a Useful Diagnostic Tool in the Emergency Setting

We retrospectively checked patients who underwent chemotherapy and/or hematopoietic stem cell transplantation from 2007 to 2016, in order to evaluate whether early computed tomography is useful in children treated for cancer with acute central nervous system complications. Out of a total sample of 443 patients, 52 children (11.7%) presented these complications. In the end, 31 patients were included, with a total of 33 events of central nervous system complications. The computed tomography was abnormal in 22 events (67%) and diagnostic for a specific complication in 20 events (61%), whereas it directly influenced the treatment in 16 events (48%). Computed tomography should be still considered a relevant diagnostic tool in the management of acute central nervous system complications in the emergency setting.

COL1A1 polymorphism and neurological complications in pediatric acute lymphoblastic leukemia patients and their associations with altered bone mineral density

Background

Osteoporosis and neurological complications are consequences of acute lymphoblastic leukemia (ALL). Collagen type I alpha 1 gene (COL1A1) polymorphism is associated with osteoporosis. This study aimed to detect the COL1A1 polymorphism and the neurological complications in ALL patients and their association with decreased lumbar spine bone mineral density (BMDLS). This study included 100 pediatric ALL patients and 100 controls. All participants were subjected to laboratory assessment and assessment of BMDLS at the start of the study and 3 years later. COLIA1 genotyping was done once for all participants.

Results

At the start of the study, there was a significant decrease in osteocalcin (OC), alkaline phosphatase (ALP), and BMDLS levels in the patients. G/T variants and “T” alleles were significantly more detected in the patients (34% and 35% respectively); also, significant differences were detected between patients with polymorphism (G/T and T/T) and those without polymorphism (G/G) regarding OC, ALP, and BMDLS. After 3 years, significant decrement in BMDLS, OC, and ALP was detected in the patients. Twenty-four patients had neurological complications and seven patients had bone fractures. Those patients had significant decrement in BMDLS, OC, and ALP levels. As regards COL1A1 gene polymorphism, the GT and TT variants were significantly detected in fractured patients, while there was no significant difference regarding GT and TT variants in the patients with neurological complications. T allele, neurological complications, high-risk stratification, and age were significantly associated with decreased BMDLS. T allele was the most significant risk factor.

Conclusion

COLIA1 gene polymorphism, decreased BMDLS, and neurological complications were significantly detected in pediatric ALL patients. COLIA1 gene polymorphism is a significant risk factor for decreased BMDLS in pediatric ALL patients. There is no significant relation between COLIA1 gene polymorphism and the development of neurologic complications.

Revealing the molecular mechanism of central nervous system leukemia with single-cell technology

Central nervous system leukemia (CNSL) is a severe complication of acute leukemia, with serious consequences for life quality and expectancy. The molecular mechanism of CNSL is unclear at present. Thus, determining appropriate prevention and therapeutic strategies for CNSL remain challenging. Currently, inferences regarding gene functions are based on the measurement of average gene expression in a bulk lysate. However, leukemia cells are a heterogeneous population in which the expression of critical genes may be masked by many unrelated genes. Single-cell sequencing may therefore be the best way to explore the development of CNSL in the bone marrow and peripheral blood at diagnosis and subsequent time points, in order to detect potential targets and prevent the development of CNSL. In this review, we first discuss the possible mechanism of CNSL, then describe the heterogeneity of leukemia cells. Finally, we focus on the role of single-cell technology in preventing and treating CNSL.

Seizures during treatment of childhood acute lymphoblastic leukemia: A population-based cohort study

BACKGROUND

Seizures are common in children with acute lymphoblastic leukemia (ALL). As ALL survival rates are improving, the challenge to minimize treatment related side effects and late sequelae rises. Here, we studied the frequency, timing, etiology and risk factors of seizures in ALL patients.

METHODS

The study included children aged 1-17.9 years at diagnosis of B-cell-precursor and T cell ALL who were treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol between 2008 and 2015. Detailed patient data were acquired from the NOPHO ALL2008 registry and by review of medical records.

RESULTS

Seizures occurred in 81/1464 (5.5%) patients. The cumulative incidence of seizures at one months was 1.7% (95% CI: 1.2-2.5) and at one year 5.3% (95% CI 4.2-6.5%). Patients aged 10-17.9 years, those with T cell immunophenotype, CNS involvement, or high-risk induction with dexamethasone had higher risk for seizures in univariable analyses. Only age remained a risk factor in multivariable analyses (the cumulative incidence of seizures for patients 10-17.9 years old at one year was 9.0% (95% CI: 6.2-12.9)). Of the 81 patients with seizures, 43 had posterior reversible encephalopathy syndrome (PRES), 15 had isolated seizures, nine had sinus venous thrombosis (SVT), three had stroke-like syndrome, and 11 had other neurotoxicities. Epilepsy diagnosis was reported in totally 11 ALL survivors at last follow up.

CONCLUSION

Seizures are relatively common in ALL patients and occur most often in patients with PRES, SVT, or as an isolated symptom. Older children have higher risk of seizures.

Characterization of pharmacogenetic markers related to Acute Lymphoblastic Leukemia toxicity in Amazonian native Americans population

Acute Lymphoblastic Leukemia (ALL) is the most common cancer in children. Differences are found among ethnic groups in the results of the treatment of pediatric ALL. In general, children with a high level of native American ancestry tend to respond less positively to ALL treatments, which may be related to specific genomic variants found in native American groups. Despite the evidence, few data are available on the distribution of the pharmacogenomic variants relevant to the treatment of ALL in traditional Amerindian populations, such the those of the Amazon region. Given this, the present study investigated 27 molecular markers related to the treatment of ALL in Amerindians from Brazilian Amazonia and compared the frequencies with those recorded previously on five continents, that are available in the 1,000 Genomes database. The variation in the genotype frequencies among populations was evaluated using Fisher's exact test. The False Discovery Rate method was used to correct the results of the multiple analyses. Significant differences were found in the frequencies of the majority of markers between the Amerindian populations and those of other regions around the world. These findings highlight the unique genetic profile of the indigenous population of Brazilian Amazonia, which may reflect a distinct therapeutic profile for the treatment of ALL in these populations.

Methotrexate-induced Acute Myelopathy in a Teenager With High-risk Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is one of the most frequent malignancies in childhood whose long-term survival has increased up to 80% thanks to modern therapy enhancements. Nevertheless, methotrexate (MTX) remains a mainstay of ALL therapy, but also represents one of the major causes of neurotoxicity in patients with ALL. MTX-induced toxicity occurs in about 9% of patients treated for ALL. It usually affects deep white matter region leading to leukoencephalopathy, which has varying clinical manifestations ranging from acute neurologic disturbances to seizures or chronic permanent encephalopathy. Here we describe a 13-year-old girl affected with ALL who developed lower limbs hypesthesia and static ataxia due to transverse myelopathy after intrathec administration of MTX therapy. A high-dose corticotherapy combined to vitamin supplementation and rehabilitation was tested. Neurological evolution was characterized by slow and partial recovery.

Successful therapeutic rechallenge after a severe episode of high dose methotrexate-induced choreoathetosis: A case report

Methotrexate (MTX) is an essential chemotherapy drug used in the treatment of malignancies, but it is known to cause complications to the central nervous system. We report a case of severe MTX neurotoxicity in an adult presenting with choreoathetosis despite a normal clearance of MTX. High dose-MTX has been successfully rechallenged without any neurological sequelae. We reviewed the relevant literature of similar manifestations and summarized their clinical data, magnetic resonance imaging features and treatment given. None of them has recurrence of neurotoxicity. We concluded that it is safe to persist with MTX even after a previous episode of toxic leukoencephalopathy.

Clinical Implications of Methotrexate Pharmacogenetics in Childhood Acute Lymphoblastic Leukaemia

Background:

In the past two decades, a great body of research has been published regarding the effects of genetic polymorphisms on methotrexate (MTX)-induced toxicity and efficacy. Of particular interest is the role of this compound in childhood acute lymphoblastic leukaemia (ALL), where it is a pivotal drug in the different treatment protocols, both at low and high doses. MTX acts on a variety of target enzymes in the folates cycle, as well as being transported out and into of the cell by several transmembrane proteins.

Methods:

We undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question.

Results:

This review has intended to summarize the current knowledge concerning the clinical impact of polymorphisms in enzymes and transporters involved in MTX disposition and mechanism of action on paediatric patients with ALL.

Conclusion:

In this work, we describe why, in spite of the significant research efforts, pharmacogenetics findings in this setting have not yet found their way into routine clinical practice.

Leukemia Cell Cycle Chemical Profiling Identifies the G2-Phase Leukemia Specific Inhibitor Leusin-1

Targeting the leukemia proliferation cycle has been a successful approach to developing antileukemic therapies. However, drug screening efforts to identify novel antileukemic agents have been hampered by the lack of a suitable high-throughput screening platform for suspension cells that does not rely on flow-cytometry analyses. We report the development of a novel leukemia cell-based high-throughput chemical screening platform for the discovery of cell cycle phase specific inhibitors that utilizes chemical cell cycle profiling. We have used this approach to analyze the cell cycle response of acute lymphoblastic leukemia CCRF-CEM cells to each of 181420 druglike compounds. This approach yielded cell cycle phase specific inhibitors of leukemia cell proliferation. Further analyses of the top G2-phase and M-phase inhibitors identified the leukemia specific inhibitor 1 (Leusin-1). Leusin-1 arrests cells in G2 phase and triggers an apoptotic cell death. Most importantly, Leusin-1 was more active in acute lymphoblastic leukemia cells than other types of leukemias, non-blood cancers, or normal cells and represents a lead molecule for developing antileukemic drugs.

Motor function in survivors of pediatric acute lymphoblastic leukemia treated with chemotherapy-only

BACKGROUND

Up to 43% of survivors of pediatric acute lymphoblastic leukemia (ALL) may exhibit fine-motor problems. Information on manual dexterity in this cohort is still limited.

OBJECTIVES

We tested survivors of childhood ALL treated with chemotherapy-only for fine-motor function in terms of drawing and handwriting abilities using a Digitizing Tablet (DT) with three tasks for drawing and handwriting of varying complexity, for ataxia using the International Cooperative Ataxia Rating Scale (ICARS), and for tremor and hand-eye coordination using the Nine Hole Steadiness Tester (NHST).

RESULTS

We examined a cohort of non-irradiated survivors (n = 31) after a median time of 3.5 years after end of therapy. In all tasks of the DT the cohort demonstrated significant (p < 0.05) impairment of speed, automation, and variability in at least two tasks and significantly more pressure. Impaired speed (SPV) inversely correlated with lag time since end of therapy. Dexterity performance of six survivors (19%) lay below the 5th percentile. No survivor exhibited ataxia, tremor, or impaired hand-steadiness.

CONCLUSION

Despite the absence of gross ataxia, tremor, and impaired hand-eye coordination, we nevertheless detected significant fine-motor impairment in a relevant number of survivors of childhood ALL. Prospective studies are needed to reveal the pathophysiological underpinnings and genetic risk factors for development of such deficits due to ALL and its treatment.

Toxic-Metabolic Neurologic Disorders in Children: A Neuroimaging Review

There are multiple causes of neurotoxicity in children including medications, extrinsic toxins and insults, illicit drugs, built up of toxic metabolites due to genetic or acquired disorders, and metabolic abnormalities. The review is centered on causes of neurotoxicity affecting the pediatric brain and producing typical and easily recognized imaging manifestations. Early identification of common and less common imaging findings may point toward the correct direction, and may facilitate early diagnosis and institution of appropriate treatment to reverse or at least limit the injury to the developing brain. Two common imaging patterns of neurotoxicity in children are the posterior reversible encephalopathy syndrome and acute toxic leukoencephalopathy that are usually related to chemotherapy and immunosuppression for common pediatric malignancies. Another well-described imaging pattern of injury in children involves reversible splenial lesions with or without associated white matter abnormalities. Multiple additional extrinsic causes of neurotoxicity are presented including radiation and chemoradiation, various medications and treatment regimens, poisoning, illicit drug use or accidental exposure, and the respective characteristic neuroimaging findings are highlighted. Intrinsic neurotoxicity may occur in the setting of inborn errors of metabolism or acquired progressive organ failure leading to build up of toxic metabolites. Additional intrinsic causes of neurotoxicity include metabolic derangements and characteristic imaging findings in all instances are reviewed. The goal of the article is to enhance familiarity of neurologists and neuroradiologists with the imaging appearance of common and less common toxic insults to the pediatric brain.

Delivery of Methotrexate and Characterization of Skin Treated by Fabricated PLGA Microneedles and Fractional Ablative Laser

PURPOSE

This study investigated in vitro transdermal delivery of methotrexate through dermatomed porcine ear and cadaver human skin treated with poly (D,L-lactide-co-glycolide) acid microneedles or fractional ablative laser.

METHODS

PLGA microneedles were fabricated and characterized using scanning electron microscopy and mechanical assessment techniques. The integrity of treated skin was evaluated by rheometer, transepidermal water loss, and skin electrical resistance measurements. Successful skin microporation was demonstrated by dye binding, histology, pore uniformity, confocal laser microscopy, and DermaScan studies. In vitro permeation experiment was performed on Franz diffusion cells to determine drug delivery into and across the skin.

RESULTS

Both physical treatments resulted in a considerable decrease in skin resistance and an increase in transepidermal water loss value. The laser-created microchannels were significantly larger than those formed by microneedles (p < 0.05). An effective force of 41.04 ± 18.33 N was required to achieve 100% penetration efficiency of the microneedles. For both porcine ear and human skin, laser ablation provided a significantly higher methotrexate permeability into the receptor chamber and skin layers compared to microneedle poration and untreated skin (p < 0.05).

CONCLUSIONS

Both fractional ablative laser and polymeric microneedles markedly enhanced in vitro transdermal delivery of methotrexate into and across skin. Graphical Abstract ᅟ.

The Promise of Pharmacogenomics in Reducing Toxicity During Acute Lymphoblastic Leukemia Maintenance Treatment

Pediatric acute lymphoblastic leukemia (ALL) affects a substantial number of children every year and requires a long and rigorous course of chemotherapy treatments in three stages, with the longest phase, the maintenance phase, lasting 2–3 years. While the primary drugs used in the maintenance phase, 6-mercaptopurine (6-MP) and methotrexate (MTX), are necessary for decreasing risk of relapse, they also have potentially serious toxicities, including myelosuppression, which may be life-threatening, and gastrointestinal toxicity. For both drugs, pharmacogenomic factors have been identified that could explain a large amount of the variance in toxicity between patients, and may serve as effective predictors of toxicity during the maintenance phase of ALL treatment. 6-MP toxicity is associated with polymorphisms in the genes encoding thiopurine methyltransferase (TPMT), nudix hydrolase 15 (NUDT15), and potentially inosine triphosphatase (ITPA), which vary between ethnic groups. Moreover, MTX toxicity is associated with polymorphisms in genes encoding solute carrier organic anion transporter family member 1B1 (SLCO1B1) and dihydrofolate reductase (DHFR). Additional polymorphisms potentially associated with toxicities for MTX have also been identified, including those in the genes encoding solute carrier family 19 member 1 (SLC19A1) and thymidylate synthetase (TYMS), but their contributions have not yet been well quantified. It is clear that pharmacogenomics should be incorporated as a dosage-calibrating tool in pediatric ALL treatment in order to predict and minimize the occurrence of serious toxicities for these patients.

Pediatric arterial ischemic stroke: Epidemiology, risk factors, and management

Pediatric arterial ischemic stroke (AIS) is an uncommon but important cause of neurologic morbidity in neonates and children, with consequences including hemiparesis, intellectual disabilities, and epilepsy. The causes of pediatric AIS are unique to those typically associated with stroke in adults. Familiarity with the risk factors for AIS in children will help with efficient diagnosis, which is unfortunately frequently delayed. Here we review the epidemiology and risk factors for AIS in neonates and children. We also outline consensus-based practices in the evaluation and management of pediatric AIS. Finally we discuss the outcomes observed in this population. While much has been learned in recent decades, many uncertainties sill persist in regard to pediatric AIS. The ongoing development of specialized centers and investigators dedicated to pediatric stroke will continue to answer such questions and improve our ability to effectively care for these patients.

Central Nervous System Complications in Children Receiving Chemotherapy or Hematopoietic Stem Cell Transplantation

Therapy-related neurotoxicity greatly affects possibility of survival and quality of life of pediatric patients treated for cancer. Central nervous system (CNS) involvement is heterogeneous, varying from very mild and transient symptoms to extremely severe and debilitating, or even lethal syndromes. In this review, we will discuss the broad scenario of CNS complications and toxicities occurring during the treatment of pediatric patients receiving both chemotherapies and hematopoietic stem cell transplantation. Different types of complications are reviewed ranging from therapy related to cerebrovascular with a specific focus on neuroradiologic and clinical features.

Evaluation of standardized triple intrathecal therapy toxicity in oncohematological pediatric patients

Background The administration of triple intrathecal therapy with methotrexate, cytarabine and a corticosteroid for the prophylaxis and treatment of neoplastic cell infiltration in the central nervous system in hematological malignancies is a widespread practice. There is limited information available about its toxicity profile. Several factors related to intrathecal preparation can affect toxicity. Thus, it was decided to standardize intrathecal chemotherapy, trying to obtain the best toxicity profile. Objective To assess the toxicity of a standardized triple intrathecal chemotherapy in oncohematological pediatric patients and to establish risk factors of toxicity. Setting Oncohematological pediatric unit from a tertiary hospital in Spain. Methods Prospective, descriptive and observational study in which all the administrations of standardized triple intrathecal chemotherapy in pediatric patients were registered. Main outcome measure Toxicity of the intrathecal therapy was recorded and possible risk factors were assessed. Results A total of 269 administrations of triple intrathecal chemotherapy were registered in 41 patients (mean age = 6.6 ± 3.9 years). In 16.7% of the procedures, an adverse event was reported (total number of adverse events = 61). 47.5% were grade 1, 47.5% grade 2 and 4.9% grade 3. The administration of intrathecal chemotherapy inpatient and patient age ≥3 years were risk factors of toxicity in the multivariate analysis. Conclusions The administration of standardized triple intrathecal chemotherapy is related to a low frequency of toxicity and most of the adverse events registered were mild/moderate. The detection of adverse effects was significantly greater in children with age greater than or equal to three years and in hospitalized patients.

Adverse neuropsychological effects associated with cumulative doses of corticosteroids to treat childhood acute lymphoblastic leukemia: A literature review

Corticosteroids (CS) are an essential component of childhood acute lymphoblastic leukemia treatments (cALL). Although there is evidence that daily doses of CS can have neuropsychological effects, few studies have investigated the role of cumulative doses of CS in short- and long-term neuropsychological effects in cALL. The aims of this review were to identify the measures used for documenting adverse neuropsychological effects (ANEs) of CS treatment and to study the association between cumulative doses of CS and the presence of ANEs. Twenty-two articles met the inclusion criteria. A variety of measures were used to evaluate outcomes in the domains of emotion, behaviour, neurocognition, and fatigue/sleep. The results suggest that we cannot conclude in favour of an association between the cumulative dosage of CS and ANEs. Yet, several factors including the heterogeneity of measures used to evaluate outcomes and reporting biases may limit the scope of the results. We offer several recommendations that could help improve the future published evidence on ANEs in relation to CS treatment in cALL.

Severe Cerebral Vasospasm and Childhood Arterial Ischemic Stroke After Intrathecal Cytarabine

We report on 2 patients who developed widespread cerebral vasospasm and arterial ischemic strokes (AIS) after application of intrathecal (IT) cytarabine. In a 3-year-old child with acute lymphoblastic leukemia (ALL), left leg weakness, hyperreflexia, and clonus were noted 4 days after her first dose of IT cytarabine during the induction phase of her chemotherapy. Cerebral MRI revealed multiple acute cerebral ischemic infarcts and widespread cerebral vasospasm. A 5-year-old girl complained of right arm and leg pain and began limping 11 days after IT cytarabine. Symptoms progressed to right dense hemiplegia, left gaze deviation, headache, and speech arrest. MRI revealed 2 large cortical areas of diffusion restriction in the right frontal and left parietal lobes. Cerebral magnetic resonance angiography (MRA) showed irregular narrowing affecting much of the intracranial arterial circulation. Although the first child fully recovered from her neurologic symptoms, the second patient had persistent hemiplegia on follow-up. Including this report, there are now 4 pediatric ALL cases of severe cerebral vasospasm and AIS in the context of IT cytarabine administration, strongly suggesting a true association. Differential diagnosis and management issues are discussed. Along with the more widespread use of MRI and MRA, the true frequency of this severe adverse effect will become clearer in future. For any child with neurologic symptoms within hours or days of receiving IT cytarabine, a low threshold for cerebral imaging with MRI and MRA is recommended.

Central nervous system acute lymphoblastic leukemia: role of natural killer cells

Central nervous system acute lymphoblastic leukemia (CNS-ALL) is a major clinical problem. Prophylactic therapy is neurotoxic, and a third of the relapses involve the CNS. Increased expression of interleukin 15 (IL-15) in leukemic blasts is associated with increased risk for CNS-ALL. Using in vivo models for CNS leukemia caused by mouse T-ALL and human xenografts of ALL cells, we demonstrate that expression of IL-15 in leukemic cells is associated with the activation of natural killer (NK) cells. This activation limits the outgrowth of leukemic cells in the periphery, but less in the CNS because NK cells are excluded from the CNS. Depletion of NK cells in NOD/SCID mice enabled combined systemic and CNS leukemia of human pre-B-ALL. The killing of human leukemia lymphoblasts by NK cells depended on the expression of the NKG2D receptor. Analysis of bone marrow (BM) diagnostic samples derived from children with subsequent CNS-ALL revealed a significantly high expression of the NKG2D and NKp44 receptors. We suggest that the CNS may be an immunologic sanctuary protected from NK-cell activity. CNS prophylactic therapy may thus be needed with emerging NK cell-based therapies against hematopoietic malignancies.

Pharmacogenetics predictive of response and toxicity in acute lymphoblastic leukemia therapy

Acute lymphoblastic leukemia (ALL) is a relatively rare disease in adults accounting for no more than 20% of all cases of acute leukemia. By contrast with the pediatric population, in whom significant improvements in long term survival and even cure have been achieved over the last 30years, adult ALL remains a significant challenge. Overall survival in this group remains a relatively poor 20-40%. Modern research has focused on improved pharmacokinetics, novel pharmacogenetics and personalized principles to optimize the efficacy of the treatment while reducing toxicity. Here we review the pharmacogenetics of medications used in the management of patients with ALL, including l-asparaginase, glucocorticoids, 6-mercaptopurine, methotrexate, vincristine and tyrosine kinase inhibitors. Incorporating recent pharmacogenetic data, mainly from pediatric ALL, will provide novel perspective of predicting response and toxicity in both pediatric and adult ALL therapies.

Neurologic morbidity and quality of life in survivors of childhood acute lymphoblastic leukemia: a prospective cross-sectional study

PURPOSE

Childhood acute lymphoblastic leukemia (ALL) is treated with potentially neurotoxic drugs and neurologic complications in long-term survivors are inadequately studied. This study investigated neurologic morbidity and its effect on quality of life in long-term survivors of childhood ALL.

METHODS

Prospective, single institution, cross-sectional, institutional review board-approved study of long-term ALL survivors. Participants were recruited from institutional clinics. Participants answered an investigator-administered questionnaire followed by evaluation by a neurologist. Quality of life (QOL) was also assessed.

RESULTS

Of the 162 participants recruited over a 3-year period, 83.3% reported at least one neurologic symptom of interest, 16.7% had single symptom, 11.1% had two symptoms, and 55.6% had three or more symptoms. Symptoms were mild and disability was low in the majority of participants with neurologic symptoms. Median age at ALL diagnosis was 3.9 years (0.4-18.6), median age at study enrollment was 15.7 years (6.9-28.9), and median time from completion of ALL therapy was 7.4 years (1.9-20.3). On multivariable analyses, female sex correlated with presence of dizziness, urinary incontinence, constipation, and neuropathy; use of ≥10 doses of triple intrathecal chemotherapy correlated with urinary incontinence, back pain, and neuropathy; cranial radiation with ataxia; history of ALL relapse with fatigue; and CNS leukemia at diagnosis with seizures. Decline in mental QOL was associated with migraine and tension type headaches, while physical QOL was impaired by presence of dizziness and falls. Overall, good QOL and physical function was maintained by a majority of participants.

CONCLUSIONS

Neurologic symptoms were present in 83% long-term ALL survivors. Symptoms related morbidity and QOL impairment is low in majority of survivors. Female sex, ≥10 doses of intrathecal chemotherapy, and history of ALL relapse predispose to impaired QOL.

IMPLICATIONS FOR CANCER SURVIVORS

This study will educate survivors and their care providers regarding cancer or treatment-related neurologic symptoms and morbidity. This study will help them understand factors contributing to impaired QOL when present.

Transdermal delivery of methotrexate for pediatrics using silicon microneedles

Background: The objective of this work was to study transdermal delivery of methotrexate using silicon microneedles and simulate plasma concentrations using a population pharmacokinetic model. Results: Characterization of silicon microneedles was carried out by scanning electron microscopy, transepidermal water loss, methylene blue staining, calcein imaging, pore permeability index and confocal microscopy, which confirmed the formation of microchannels. In vitro permeation studies were performed to study the enhancement in transdermal delivery following microporation. Conclusion: Simulation data demonstrated that with 16, 64, 128 and 192 microneedles, mean plasma concentrations of 0.3, 1.4, 2.8 and 4.2 ng/ml, respectively, can be achieved. Thus, therapeutically relevant doses could be delivered in pediatrics by increasing the number of microneedles and patch area.

Impact of genetic polymorphisms on chemotherapy toxicity in childhood acute lymphoblastic leukemia

The efficacy of chemotherapy in pediatric acute lymphoblastic leukemia (ALL) patients has significantly increased in the last 20 years; as a result, the focus of research is slowly shifting from trying to increase survival rates to reduce chemotherapy-related toxicity. At the present time, the cornerstone of therapy for ALL is still formed by a reduced number of drugs with a highly toxic profile. In recent years, a number of genetic polymorphisms have been identified that can play a significant role in modifying the pharmacokinetics and pharmacodynamics of these drugs. The best example is that of the TPMT gene, whose genotyping is being incorporated to clinical practice in order to individualize doses of mercaptopurine. However, there are additional genes that are relevant for the metabolism, activity, and/or transport of other chemotherapy drugs that are widely use in ALL, such as methotrexate, cyclophosphamide, vincristine, L-asparaginase, etoposide, cytarabine, or cytotoxic antibiotics. These genes can also be affected by genetic alterations that could therefore have clinical consequences. In this review we will discuss recent data on this field, with special focus on those polymorphisms that could be used in clinical practice to tailor chemotherapy for ALL in order to reduce the occurrence of serious adverse effects.