Methotrexate-induced side effects are not due to differences in pharmacokinetics in children with Down syndrome and acute lymphoblastic leukemia

Azacitidine treatment for myeloid leukemia associated with Down syndrome: A nationwide retrospective study in Japan

Hypomethylating agent treatment for myeloid leukemia associated with Down syndrome (ML-DS) has been scarcely reported. Herein, we collected information on azacitidine treatment for ML-DS in Japan. Forty-eight cycles of azacitidine treatment were performed for 12 patients, including 11 relapsed or refractory (R/R) patients. In 40 cycles, azacitidine was used as monotherapy. No azacitidine-related death was observed. One cycle concurrently administered with methotrexate-based intrathecal therapy was discontinued due to toxicities. Only 4 of the 19 cycles given in non-remission achieved complete or partial remission. In conclusion, although most toxicities were acceptable, azacitidine monotherapy might be insufficient for R/R ML-DS cases.

Population pharmacokinetic analyses of methotrexate in pediatric patients: a systematic review

BACKGROUND AND OBJECTIVES

Methotrexate is widely utilized in the chemotherapy of malignant tumors and autoimmune diseases in the pediatric population, but dosing can be challenging. Several population pharmacokinetic models were developed to characterize factors influencing variability and improve individualization of dosing regimens. However, significant covariates included varied across studies. The primary objective of this review was to summarize and discuss population pharmacokinetic models of methotrexate and covariates that influence pharmacokinetic variability in pediatric patients.

METHODS

Systematic searches were conducted in the PubMed and EMBASE databases from inception to 7 July 2023. Reporting Quality was evaluated based on a checklist with 31 items. The characteristics of studies and information for model construction and validation were extracted, summarized, and discussed.

RESULTS

Eighteen studies (four prospective studies and fourteen retrospective studies with sample sizes of 14 to 772 patients and 2.7 to 93.1 samples per patient) were included in this study. Two-compartment models were the commonly used structural models for methotrexate, and the clearance range of methotrexate ranged from 2.32 to 19.03 L/h (median: 6.86 L/h). Body size and renal function were found to significantly affect the clearance of methotrexate for pediatric patients. There were limited reports on the role of other covariates, such as gene polymorphisms and co-medications, in the pharmacokinetic parameters of methotrexate pediatric patients. Internal and external evaluations were used to assess the performance of the population pharmacokinetic models.

CONCLUSION

A more rigorous external evaluation needs to be performed before routine clinical use to select the appropriate PopPK model. Further research is necessary to incorporate larger cohorts or pool analyses in specific susceptible pediatric populations to improve the understanding of predicted exposure profiles and covariate identification.

Clinical Course and Cytokine Profile of Systemic Juvenile Idiopathic Arthritis in a Patient with Trisomy 21

Trisomy 21 (Down syndrome) is sometimes complicated by congenital heart disease; however, comorbid type I diabetes mellitus and diseases involving autoantibodies, such as Hashimoto disease and Graves disease, are not uncommon. Autoinflammatory diseases such as Kawasaki disease and systemic juvenile idiopathic arthritis are rare. We report a rare case of trisomy 21 with systemic juvenile idiopathic arthritis that responded well to the initial course of methylprednisolone pulse therapy but flared up and was complicated by macrophage activation syndrome (MAS). Subsequent methylprednisolone pulse therapy and cyclosporine resolved this condition. Cytokines were analyzed at several time points during the clinical course and revealed that interleukin-18, interleukin-6, and chemokine ligand 9 levels were elevated at MAS onset in the present patient, even though clinical symptoms had abated. Thus, early analysis of cytokine profiles should be performed to assess MAS risk and determine treatment intensity, even in T21 patients.

Population Pharmacokinetic Model of Methotrexate in Brazilian Pediatric Patients with Acute Lymphoblastic Leukemia

OBJECTIVES

Methotrexate (MTX) is subject to therapeutic drug monitoring because of its high pharmacokinetic variability and safety risk outside the therapeutic window. This study aimed to develop a population pharmacokinetic model (popPK) of MTX for Brazilian pediatric acute lymphoblastic leukemia (ALL) patients who attended the Hospital de Clínicas de Porto Alegre, Brazil.

METHODS

The model was developed using NONMEM 7.4 (Icon®), ADVAN3 TRANS4, and FOCE-I. To explain inter-individual variability, we evaluated covariates from demographic, biochemical, and genetic data (single nucleotide polymorphisms [SNPs] related to the transport and metabolism of drugs).

RESULTS

A two-compartment model was built using 483 data points from 45 patients (0.33-17.83 years of age) treated with MTX (0.25-5 g/m2) in different cycles. Serum creatinine (SCR), height (HT), blood urea nitrogen (BUN) and a low BMI stratification (according to the z-score defined by the World Health Organization [LowBMI]) were added as clearance covariates. The final model described MTX clearance as [Formula: see text]. In the two-compartment structural model, the central and peripheral compartment volumes were 26.8 L and 8.47 L, respectively, and the inter-compartmental clearance was 0.218 L/h. External validation of the model was performed through a visual predictive test and metrics using data from 15 other pediatric ALL patients.

CONCLUSION

The first popPK model of MTX was developed for Brazilian pediatric ALL patients, which showed that inter-individual variability was explained by renal function and factors related to body size.

Participation, challenges and needs in children with down syndrome during cancer treatment at hospital: a qualitative study of parents' experiences

Background

Studies report that it can be challenging to assess and treat side-effects and symptoms among children who have impairments and difficulties in expressing their needs. Children with Down syndrome have an increased vulnerability and an increased risk for contracting leukaemia. There is sparse knowledge about the parental experience of how treatment and side-effects affect children with Down syndrome with leukaemia, as well as the role of participation during treatment.

Purpose

This study aimed to explore the perceptions of parents of children with Down syndrome and leukaemia regarding their child's treatment, side effects and participation during hospital care.

Methods

A qualitative study design was used, and interviews were conducted with a semi-structured interview-guide. Fourteen parents of 10 children with Down syndrome and acute lymphoblastic leukaemia from Sweden and Denmark, 1-18 years of age, participated. All children had completed therapy or had a few months left before the end of treatment. Data was analysed according to qualitative content analysis.

Results

Four sub-themes were identified: (1) Continuously dealing with the child's potential susceptibility; (2) Confidence and worries regarding decisions related to treatment regulation; (3) Challenges in communication, interpretation, and participation; and (4) Facilitating participation by adapting to the child's behavioural and cognitive needs. The sub-themes were bound together in an overarching theme, which expressed the core perception "Being the child's spokesperson to facilitate the child's participation during treatment". The parents expressed this role as self-evident to facilitate communication regarding the needs of the child, but also regarding how the cytotoxic treatment affected the vulnerable child. Parents conveyed the struggle to ensure the child's right to receive optimal treatment.

Conclusion

The study results highlight parental challenges regarding childhood disabilities and severe health conditions, as well as communication and ethical aspects regarding to act in the best interests of the child. Parents played a vital role in interpreting their child with Down syndrome. Involving parents during treatment enables a more accurate interpretation of symptoms and eases communication and participation. Still, the results raise questions regarding issues related to building trust in healthcare professionals in a context where medical, psychosocial and ethical dilemmas are present.

Down Syndrome-Associated Arthritis (DA): Diagnostic and Management Challenges

Down syndrome (DS) is one of the most common birth defects in the United States, the most common genomic disorder of intellectual disability, and results from trisomy 21. This chromosome disorder causes an extensive, heterogenous phenotype that results in a broad presentation of symptoms that includes atlantoaxial instability, congenital heart defects, muscle hypotonia, hypothyroidism, hematologic disorders, recurrent infections, and autoimmune diseases. The autoimmune diseases are caused by immune system dysregulation that results in increased pro-inflammatory cytokines, along with other innate and adaptive immune system dysregulation. This is the likely cause of the increased risk of inflammatory arthritis or Down syndrome-associated arthritis (DA) seen in individuals with DS. Most individuals with DA present with polyarticular (five or more joints with arthritis at presentation of disease), rheumatoid factor and anti-nuclear antibody negative disease that is aggressive with bone and joint damage at presentation. There is notable delay in diagnosis of DA as there are no formal guidelines on screening or monitoring for inflammatory arthritis in individuals with DS. Once diagnosed, and despite aggressive therapy with disease modifying antirheumatic drugs, disease burden is high for those with DA. Therapy can also be challenging for those with DA as many require second and third-line disease modifying therapies. Many also struggle with medication toxicity and ineffectiveness that further causes challenges with management and outcomes. The purpose of this current review is to provide an up-to-date summary of the literature related to DA in children and adolescents with focus on presentation, diagnosis, and management considerations, along with current barriers that inhibit optimal care.

Hematological disorders in children with Down syndrome

INTRODUCTION

Hematological abnormalities are common in children with down syndrome (DS), mainly during childhood.

AREAS COVERED

DS newborns can develop hematological benign conditions that resolve spontaneously within 1 -2 months. However, about 10% of them can present transient abnormal myelopoiesis (TAM), characterized by the presence of circulating blasts. About 80% of DS neonates with TAM undergo spontaneous resolution of both clinical and laboratory abnormalities within 3-6 months after birth. However, some newborns with TAM may develop acute myeloid leukemia associated with DS (ML-DS), usually after an interval without signs of leukemia. GATA1 mutations are stable molecular markers that may monitor the presence of minimal residual disease (MRD) after TAM resolution. Moreover, DS children have a 10-20-fold increased risk of developing acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). The predisposition to develop leukemia occurs both in children with complete trisomy 21 and in those with mosaic trisomy, suggesting an important role of chromosome 21 in leukemogenesis.

EXPERT OPINION

In contrast to the excellent prognosis of ML-DS obtained likewise with low doses of chemotherapy, DS-ALL patients show worse outcomes than non-DS children, therefore advances and risk-stratified treatment adjustments are mandatory for this particular set of patients.

The Clinical Spectrum of Inflammatory Bowel Disease Associated With Specific Genetic Syndromes: Two Novel Pediatric Cases and a Systematic Review

Background and Aims: Inflammatory bowel disease (IBD) is a typical polygenic disorder and less frequently shows a monogenic origin. Furthermore, IBD can originate in the context of specific genetic syndromes associated with a risk of autoimmune disorders. We aimed to systematically evaluate the prevalence of IBD in specific genetic syndromes and to review the clinical characteristics of the published cases. Methods: According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, studies describing patients with IBD and a genetic syndrome and/or studies indicating the prevalence or incidence of IBD in subjects with a genetic syndrome were included. Results: Forty-six studies describing a total of 67 cases of IBD in six genetic syndromes and two personally assessed unpublished cases were included in the review. The majority of cases were associated with Turner syndrome (TS) (38 cases), Down syndrome (DS) (18 cases) and neurofibromatosis type 1 (NF1) (8 cases). Sporadic cases were described in DiGeorge syndrome (2), Kabuki syndrome (2), and Williams syndrome (1). The prevalence of IBD ranged from 0.67 to 4% in TS and from 0.2 to 1.57% in DS. The incidence of IBD was increased in TS and DS compared to the general population. Eight cases of IBD in TS had a severe/lethal course, many of which described before the year 2000. Two IBD cases in DS were particularly severe. Conclusion: Evidence of a greater prevalence of IBD is accumulating in TS, DS, and NF1. Management of IBD in patients with these genetic conditions should consider the presence of comorbidities and possible drug toxicities. Systematic Review Registration: PROSPERO, identifier: CRD42021249820.

Population Pharmacokinetics of High-Dose Methotrexate in Chinese Pediatric Patients With Acute Lymphoblastic Leukemia

High-dose methotrexate (HD-MTX) is widely used in pediatric acute lymphoblastic leukemia (ALL) treatment regimens. In this study, we aimed to develop a population pharmacokinetic (PK) model of HD-MTX in Chinese pediatric patients with ALL for designing personalized dosage regimens. In total, 4,517 MTX serum concentration data for 311 pediatric patients with ALL, aged 0.75–15.2 years and under HD-MTX treatment, were retrospectively collected at a tertiary Children’s Hospital in China. The non-linear mixed-effect model was used to establish the population PK model, using NONMEM software. The potential covariate effects of age, body weight, and biochemical measurements (renal and liver function) on MTX PK disposition were investigated. The model was then evaluated using goodness-of-fit, visual predictive check. MTX PK disposition was described using a three-compartment model reasonable well. Body weight, implemented as a fixed allometric function on all clearance and volume of distribution parameters, showed a substantial improvement in model fit. The final population model demonstrated that the MTX clearance estimate in a typical child with body weight of 19 kg was 6.9 L/h and the central distribution of volume estimate was 20.7 L. The serum creatinine significantly affected the MTX clearance, with a 0.97% decrease in clearance per 1 μmol/L of serum creatinine. Other covariates (e.g., age, sex, bilirubin, albumin, aspartate transaminase, concomitant medication) did not significantly affect PK properties of MTX. The proposed population PK model could describe the MTX concentration data in Chinese pediatric patients with ALL. This population PK model combined with a maximum a posteriori Bayesian approach could be used to estimate individual PK parameters, and optimize personalized MTX therapy in target patients, thus aiming to reduce toxicity and improve treatment outcomes.

Evaluation of the pharmacokinetics of prednisolone in paediatric patients with acute lymphoblastic leukaemia treated according to Dutch Childhood Oncology Group protocols and its relation to treatment response

Glucocorticoids form the backbone of paediatric acute lymphoblastic leukaemia (ALL) treatment. Many studies have been performed on steroid resistance; however, few studies have addressed the relationship between dose, concentration and clinical response. The aim of the present study was to evaluate the pharmacokinetics of prednisolone in the treatment of paediatric ALL and the correlation with clinical parameters. A total of 1028 bound and unbound prednisolone plasma concentrations were available from 124 children (aged 0–18 years) with newly diagnosed ALL enrolled in the Dutch Childhood Oncology Group studies. A population pharmacokinetic model was developed and post hoc area under the curve (AUC) was tested against treatment outcome parameters. The pharmacokinetics of unbound prednisolone in plasma was best described with allometric scaling and saturable binding to proteins. Plasma protein binding decreased with age. The AUC of unbound prednisolone was not associated with any of the disease parameters or treatment outcomes. Unbound prednisolone plasma concentrations correlated with age. No effect of exposure on clinical treatment outcome parameters was observed and does not substantiate individualised dosing. Poor responders, high‐risk and relapsed patients showed a trend towards lower exposure compared to good responders. However, the group of poor responders was small and requires further research.

Population Pharmacokinetics and Pharmacodynamics of Ciprofloxacin Prophylaxis in Pediatric Acute Lymphoblastic Leukemia Patients

BACKGROUND

Ciprofloxacin is used as antimicrobial prophylaxis in pediatric acute lymphoblastic leukemia (ALL) to decrease infections with gram-negative bacteria. However, there are no clear guidelines concerning prophylactic dose.

AIMS

To determine the pharmacokinetics and pharmacodynamics (PKPD) of ciprofloxacin prophylaxis in a pediatric ALL population. The effect of patient characteristics and antileukemic treatment on ciprofloxacin exposure, the area under the concentration time curve over minimal inhibitory concentration (AUC24/MIC) ratios, and emergence of resistance were studied.

METHODS

A total of 615 samples from 129 children (0-18 years) with ALL were collected in a multicenter prospective study. A population pharmacokinetic model was developed. Microbiological cultures were collected prior to and during prophylaxis. An AUC24/MIC of ≥125 was defined as target ratio.

RESULTS

A 1-compartment model with zero-order absorption and allometric scaling best described the data. No significant (P < .01) covariates remained after backward elimination and no effect of asparaginase or azoles were found. Ciprofloxacin AUC24 was 16.9 mg*h/L in the prednisone prophase versus 29.3 mg*h/L with concomitant chemotherapy. Overall, 100%, 81%, and 18% of patients at, respectively, MIC of 0.063, 0.125, and 0.25 mg/L achieved AUC24/MIC ≥ 125. In 13% of the patients, resistant bacteria were found during prophylactic treatment.

CONCLUSION

Ciprofloxacin exposure shows an almost 2-fold change throughout the treatment of pediatric ALL. Depending on the appropriateness of 125 as target ratio, therapeutic drug monitoring or dose adjustments might be indicated for less susceptible bacteria starting from ≥ 0.125 mg/L to prevent the emergence of resistance and reach required targets for efficacy.

Treatment outcomes in children with Acute lymphoblastic leukemia with versus without coexisting Down's syndrome: A systematic review and meta-analysis

BACKGROUND

Down syndrome (DS) also known as Trisomy 21, is a chromosomal disorder affecting approximately 1 in 732newborns annually in the United States. Children with DS are more likely to develop acute lymphoblastic leukemia (ALL). For the management of pediatric ALL, different treatment protocols have been set up since years. However, ALL children with coexisting DS have shown to have increased therapy-related toxicities compared to those without DS. Therefore, in this study, we aimed to systematically analyze the treatment outcomes in acute ALL children with versus without coexisting DS.

METHODS

Electronic databases including the Web of Science, EMBASE, Cochrane Central, MEDLINE, http://www.ClinicalTrials.gov, and Google scholar were searched for publications reporting treatment related outcomes in ALL children with versus without co-existing DS. Several treatment protocols were used accordingly. This study had a long-term follow-up time period ranging from 5 to 10 years. The RevMan 5.3 software was used to carry out this analysis. Odds ratios (OR) with 95% confidence intervals (CI) were used to represent the results post analysis.

RESULTS

A total number of 31,476 children with ALL enrolled between the years 1981 and 2011 were included. Among the total number of children with ALL, 1303 had coexisting DS. Our results showed that event-free survival was similar in ALL children with versus without DS (odds ratio [OR]: 1.34, 95% confidence interval [CI]: 0.51-3.50; P = .55). Overall mortality (OR: 1.63, 95% CI: 0.86-3.10; P = .13) and participants who achieved clinical remission (OR: 1.04, 95% CI: 0.12-9.29; P = .97) were also similarly manifested. However, treatment-related mortality (OR: 4.29, 95% CI: 2.90-6.36; P = .00001) and induction failure (OR: 2.77, 95% CI: 1.08-7.07; P = .03) were significantly higher in the DS group. Also, total (OR: 1.38, 95% CI: 1.02-1.88; P = .04) and bone marrow relapses (OR: 1.29, 95% CI: 1.00-1.67; P = .05) were significantly higher in ALL children with DS. Nevertheless, central nervous system relapse (OR: 1.15, 95% CI: 0.60-2.20; P = .67), testicular relapse (OR: 0.84, 95% CI: 0.38-1.85; P = .87), and other relapses (OR: 1.12, 95% CI: 0.27-4.62; P = .88) were not significantly different when these outcomes were separately analyzed.

CONCLUSION

Based on this analysis of the treatment outcomes in ALL children with versus without DS, event-free survival, overall mortality, and patients who achieved clinical remission were similar during this long-term follow-up time period. However, due to the significantly higher treatment-related mortality, induction failure, and certain relapses in ALL children with DS, new guidelines might have to focus on reconsidering or modifying treatment regimens for ALL children with DS.

Assessment and treatment of Down syndrome-associated arthritis: a survey of pediatric rheumatologists

BACKGROUND

Inflammatory arthritis in children with Down syndrome (DS) was first described in 1984 and is now termed Down syndrome-associated arthritis (DA). Studies have shown that DA is under-recognized with a 19-month average delay in diagnosis. Additionally, most patients present with polyarticular, rheumatoid factor (RF) and anti-nuclear antibody (ANA) negative disease. Current therapies for juvenile idiopathic arthritis (JIA) have been used, but appear to be poorly tolerated, more toxic and less effective in patients with DA. There is currently no standardized approach to the assessment or management of DA. The objective of this study was to describe provider perspectives toward diagnostic and treatment approach of DA, to provide baseline information upon which to design future studies.

METHODS

An electronic survey, organized into sections regarding individual practices of assessment and treatment approach of DA, was sent to the Pediatric Rheumatology electronic list-serv. Survey responses were voluntary and results were analyzed by descriptive statistics.

RESULTS

Of 90 survey responses received, 89 were included in the analysis (one was a duplicate response). The respondents were mostly pediatric rheumatologist (94%), with greater than 10 years of experience (55%). The majority (64%) currently see 1-3 patients with DA. Most view DA as the same disease as JIA (73%), and the majority (63%) use a combination of history, exam and imaging to diagnose DA. The most ordered diagnostic tests are CBC (97%) and ESR (96%). The most used treatments include NSAIDs (94%) and methotrexate (91%) followed by anti-TNF agents (90%). Methotrexate is most administered by subcutaneous route (84%) at a dose of 15 mg/m² (56%). Oral corticosteroids were only used in 19% of the patients with DA.

CONCLUSION

This is the first study to evaluate provider perspectives towards the diagnostic and treatment approach of DA. Most pediatric rheumatologists feel that DA and JIA are synonymous, and similar approaches to diagnosis are employed, utilizing history, physical exam, laboratory tests, and imaging modalities. DA is treated similarly to JIA with initiation of NSAIDs, disease-modifying anti-rheumatic drugs and biologic therapy. More research is needed to determine optimal screening and therapeutic approach specific to DA.

Clinical implications of immune-mediated diseases in children with Down syndrome

Children with Down syndrome have changes in their innate and adaptive immunity, which contribute to increased rates of infections, autoimmune diseases, and haematological malignancies. While improved care for congenital heart disease has decreased mortality and morbidity, complications related to immune-mediated diseases continue to limit the life expectancy in Down syndrome. Infectious diseases are common and have a significant effect on development, behaviour and quality of life. Infection frequency and severity are influenced by various anatomical and physiological alterations in addition to immunological changes in Down syndrome. Thus, prevention of respiratory tract infections requires a multifactorial approach. This could include additional active and/or passive immunizations, prophylactic antibiotics, immunoglobulin replacement and ear, nose and throat surgical interventions. Autoimmune conditions like coeliac disease, type I diabetes mellitus and thyroid disease are classically mentioned in the context of Down syndrome. However, autoinflammatory conditions are more prevalent as well. Screening for autoimmune diseases is required and immunosuppression has to be used with caution. Future studies should address optimal screening programmes for immune-mediated diseases in individuals with Down syndrome, as well as the effect of immune modulation, to further decrease morbidity and mortality, and improve the quality of life of individuals with Down syndrome.

Unusual lymphoid malignancy and treatment response in two children with Down syndrome

BACKGROUND

Lymphoid malignancies other than acute lymphoblastic leukemia (ALL) are rare in children with Down syndrome (DS). Information about the toxicity of chemotherapy and prognosis is largely derived from the experience of children with DS and ALL or children without DS.

PROCEDURE

We describe the treatment and outcome of two unusual lymphoid malignancies in children with DS. One patient was diagnosed with Burkitt lymphoma (BL) and the second, after treatment for B precursor ALL, with T-cell EBV-positive proliferative disorder (LPD).

RESULTS

BL was treated with standard doses of LMB group B therapy subsequently intensified to group C therapy, including high-dose methotrexate (HD-MTX, 3-8 g/m² ). The patient did not experience excessive toxicity and remains in complete remission 13 months later. Despite presentation with disseminated disease the patient with T-cell EBV-positive LPD after treatment for B precursor ALL responded to dexamethasone and rituximab and remains in complete remission two years later.

CONCLUSIONS

Upfront reduction of the high treatment intensity, which is associated with excellent survival outcomes in BL, may not be warranted in all children with DS. Response to therapy and prognosis of T-cell EBV-positive LPD in a patient with DS was not predicted by reported experience in the absence of DS.

Methotrexate-associated toxicity in children with Down syndrome and acute lymphoblastic leukemia during consolidation therapy with high dose methotrexate according to ALL-BFM treatment regimen

Children with Down syndrome (DS) and acute lymphoblastic leukemia (ALL) often suffer from severe toxicities during treatment, especially with high-dose methotrexate (HD-MTX). Systematic data on methotrexate (MTX) toxicity in these patients are rare. We analyzed seven MTX-associated toxicities during consolidation therapy in 103 DS- and 1,109 non-DS-patients (NDS) with ALL (NDS-ALL) enrolled in ALL-Berlin–Frankfurt–Münster (ALL-BFM) trials between 1995–2016 and 1995–2007, respectively. Patients received four courses MTX (5 g/m² each) plus intrathecal MTX and 6-mercaptopurine (6-MP). From 2004 onwards, a dose of 0.5 g/m² in the first MTX course has been recommended for DS-patients. DS-patients showed higher rates of grade 3/4 toxicities after the first course with 5 g/m² MTX compared to NDS-patients (grade 3/4 toxicities 62 in 45 DS-patients vs. 516 in 1,089 NDS-patients, P<0.001). The dose reduction (0.5 g/m²) in DS-patients has reduced toxicity (39 in 51 patients, P<0.001) without increasing the relapse risk (reduced dose, 5-year cumulative relapse incidence = 0.09±0.04 vs. high dose, 0.10±0.05, P=0.51). MTX dose escalation to 1.0 g/m² for DS-patients who tolerated 0.5 g/m² (n= 28 of 51 patients) did not result in an increased rate of grade 3/4 toxicities after the second course (P=0.285). Differences in MTX plasma levels at 42 and 48 hours after the start of the first methotrexate infusion did not explain higher toxicity rates in DS-patients treated with 0.5 g/m² compared to NDS-patients treated with 5 g/m². Within the DS cohort a higher MTX plasma level was associated with increased toxicity. In conclusion, dose reduction in the first MTX course reduced severe toxicities without increasing the risk of relapse. (ClinicalTrials.gov identifier: NTC00430118, NCT01117441).

The Population Pharmacokinetics of High-Dose Methotrexate in Infants with Acute Lymphoblastic Leukemia Highlight the Need for Bedside Individualized Dose Adjustment: A Report from the Children's Oncology Group

BACKGROUND

Infants with acute lymphoblastic leukemia (ALL) treated with high-dose methotrexate may have reduced methotrexate clearance (CL) due to renal immaturity, which may predispose them to toxicity.

OBJECTIVE

The aim of this study was to develop a population pharmacokinetic (PK) model of methotrexate in infants with ALL.

METHODS

A total of 672 methotrexate plasma concentrations were obtained from 71 infants enrolled in the Children's Oncology Group (COG) Clinical Trial P9407. Infants received methotrexate 4 g/m2 intravenously for four cycles during weeks 4-12 of intensification. A population PK analysis was performed using NONMEM® version 7.4. The final model was evaluated using a non-parametric bootstrap and a visual predictive check. Simulations were performed to evaluate methotrexate dose and the utility of a bedside algorithm for dose individualization.

RESULTS

Methotrexate was best characterized by a two-compartment model with allometric scaling. Weight was the only covariate included in the final model. The coefficient of variation for interoccasion variability (IOV) on CL was relatively high at 25.4%, compared with the interindividual variability for CL and central volume of distribution (10.7% and 13.2%, respectively). Simulations identified that 21.1% of simulated infants benefitted from bedside dose adjustment, and adjustment of methotrexate doses during infusions can avoid supratherapeutic concentrations.

CONCLUSION

Infants treated with high-dose methotrexate demonstrated a relatively high degree of IOV in methotrexate CL. The magnitude of IOV in the CL of methotrexate suggests that use of a bedside algorithm may avoid supratherapeutic methotrexate concentrations resulting from high IOV in methotrexate CL.

Infantile Spasms in Children With Down Syndrome: Identification and Treatment Response

Objectives. To evaluate infantile spasms in children with Down syndrome including assessment of efficacy of treatments, presence of treatment lag, and to identify risk factors that may predict the occurrence of infantile spasms in this population. Methods. Medical charts, electroencephalograms, and brain magnetic resonance images were evaluated in 37 children treated for infantile spasms at a single institution from 2005 to 2015. Results. Mean age at diagnosis was 9.16 months, with an average 1.38-month lag from spasms onset to start of medication. Prevalence of heart defects and pulmonary hypertension were significantly higher in those with infantile spams compared with those without. Eighty-one percent receiving adrenocorticotropic hormone as initial treatment experienced remission within 2 weeks, 94.1% had remission at 3 months compared with 18.8% at 2 weeks and 35.3% at 3 months for other first-line treatments. Type of treatment was the only predictor of good outcome. Conclusions. Results stress the importance of early recognition and adrenocorticotropic hormone treatment for this seizure disorder in children with Down syndrome.

Successful Treatment of Osteosarcoma Without Methotrexate in a 13-Year-Old Boy With Down Syndrome

Osteosarcoma is the most common primary bone tumor in children, and only 1 article in the literature describes a case of osteosarcoma in a patient with Down syndrome. Although osteosarcoma is generally treated with chemotherapy regimens that include high-dose methotrexate, patients with Down syndrome have heightened sensitivity to the toxicities of methotrexate. The patient from the aforementioned case study died from sepsis soon after treatment with high-dose methotrexate. This case report describes the successful treatment of osteosarcoma in a pediatric patient with Down syndrome without methotrexate.

Precision medicine approaches may be the future for CRLF2 rearranged Down Syndrome Acute Lymphoblastic Leukaemia patients

Breakthrough studies over the past decade have uncovered unique gene fusions implicated in acute lymphoblastic leukaemia (ALL). The critical gene, cytokine receptor-like factor 2 (CRLF2), is rearranged in 5-16% of B-ALL, comprising 50% of Philadelphia-like ALL and cooperates with genomic lesions in the Jak, Mapk and Ras signalling pathways. Children with Down Syndrome (DS) have a predisposition to developing CRLF2 rearranged-ALL which is observed in 60% of DS-ALL patients. These patients experience a poor survival outcome. Mutations of genes involved in epigenetic regulation are more prevalent in DS-ALL patients than non-DS ALL patients, highlighting the potential for alternative treatment strategies. DS-ALL patients also suffer greater treatment-related toxicity from current ALL treatment regimens compared to non-DS-ALL patients. An increased gene dosage of critical genes on chromosome 21 which have roles in purine synthesis and folate transport may contribute. As the genomic landscape of DS-ALL patients is different to non-DS-ALL patients, targeted therapies for individual lesions may improve outcomes. Therapeutically targeting each rearrangement with targeted or combination therapy that will perturb the transforming signalling pathways will likely improve the poor survival rates of this subset of patients.

Morphine Pharmacokinetics in Children With Down Syndrome Following Cardiac Surgery

OBJECTIVES

To assess if morphine pharmacokinetics are different in children with Down syndrome when compared with children without Down syndrome.

DESIGN

Prospective single-center study including subjects with Down syndrome undergoing cardiac surgery (neonate to 18 yr old) matched by age and cardiac lesion with non-Down syndrome controls. Subjects were placed on a postoperative morphine infusion that was adjusted as clinically necessary, and blood was sampled to measure morphine and its metabolites concentrations. Morphine bolus dosing was used as needed, and total dose was tracked. Infusions were continued for 24 hours or until patients were extubated, whichever came first. Postinfusion, blood samples were continued for 24 hours for further evaluation of kinetics. If patients continued to require opioid, a nonmorphine alternative was used. Morphine concentrations were determined using a unique validated liquid chromatography tandem-mass spectrometry assay using dried blood spotting as opposed to large whole blood samples. Morphine concentration versus time data was modeled using population pharmacokinetics.

SETTING

A 16-bed cardiac ICU at an university-affiliated hospital.

PATIENTS

Forty-two patients (20 Down syndrome, 22 controls) were enrolled.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The pharmacokinetics of morphine in pediatric patients with and without Down syndrome following cardiac surgery were analyzed. No significant difference was found in the patient characteristics or variables assessed including morphine total dose or time on infusion. Time mechanically ventilated was longer in children with Down syndrome, and regarding morphine pharmacokinetics, the covariates analyzed were age, weight, presence of Down syndrome, and gender. Only age was found to be significant.

CONCLUSIONS

This study did not detect a significant difference in morphine pharmacokinetics between Down syndrome and non-Down syndrome children with congenital heart disease.

Prognostic factors and treatment of pediatric acute lymphoblastic leukemia

The event-free survival (EFS) for pediatric acute lymphoblastic leukemia (ALL) has shown remarkable improvement in the past several decades. In Korea also, a recent study showed 10-year EFS of 78.5%. Much of the improved outcome for pediatric ALL stems from the accurate identification of prognostic factors, the designation of risk group based on these factors, and treatment of appropriate duration and intensity according to risk group, done within the setting of cooperative clinical trials. The schema of first-line therapy for ALL remains mostly unchanged, although many groups have now reported on the elimination of cranial irradiation in all patients with low rates of central nervous system relapse. Specific high risk subgroups, such as Philadelphia chromosome-positive (Ph+) ALL and infant ALL continue to have significantly lower survival than other ALL patients. The introduction of tyrosine kinase inhibitors into therapy has led to enhanced outcome for Ph+ ALL patients. Infant ALL patients, particularly those with MLL rearrangements, continue to have poor outcome, despite treatment intensification including allogeneic hematopoietic cell transplantation. Relapsed ALL is a leading cause of mortality in pediatric cancer. Recent advances in immunotherapy targeting the CD19 of the ALL blast have shown remarkable efficacy in some of these relapsed and refractory patients. With improved survival, much of the current focus is on decreasing the long-term toxicities of treatment.

Non-infectious chemotherapy-associated acute toxicities during childhood acute lymphoblastic leukemia therapy

During chemotherapy for childhood acute lymphoblastic leukemia, all organs can be affected by severe acute side effects, the most common being opportunistic infections, mucositis, central or peripheral neuropathy (or both), bone toxicities (including osteonecrosis), thromboembolism, sinusoidal obstruction syndrome, endocrinopathies (especially steroid-induced adrenal insufficiency and hyperglycemia), high-dose methotrexate-induced nephrotoxicity, asparaginase-associated hypersensitivity, pancreatitis, and hyperlipidemia. Few of the non-infectious acute toxicities are associated with clinically useful risk factors, and across study groups there has been wide diversity in toxicity definitions, capture strategies, and reporting, thus hampering meaningful comparisons of toxicity incidences for different leukemia protocols. Since treatment of acute lymphoblastic leukemia now yields 5-year overall survival rates above 90%, there is a need for strategies for assessing the burden of toxicities in the overall evaluation of anti-leukemic therapy programs.

Clinical presentation and risk factors of serious infections in children with Down syndrome treated for acute lymphoblastic leukemia

BACKGROUND

Treatment of acute lymphoblastic leukemia (ALL) in children with Down syndrome (DS) is associated with a higher incidence of life-threatening infections compared to the overall pediatric population. The objective of this study was to describe infections and identify risk factors of microbiologically documented infections at a sterile site in children with DS during chemotherapy for ALL.

PROCEDURE

We conducted a single-institution retrospective review of infectious episodes encountered by patients with DS during primary treatment for ALL. Correlations between features of clinical presentation and severity of microbiologically proven infections were investigated.

RESULTS

Among 237 suspected infectious episodes encountered by 35 patients with DS and ALL (DS-ALL), a total of 40 episodes (16.9%) had the clinical presentation of a severe infection (SI). Seventeen patients had 33 (13.9%) microbiologically proven infections from a sterile site. Fever was not part of the clinical presentation in 27% of microbiologically documented infectious episodes. The odds ratio of a microbiologically proven infection at a sterile site was significantly increased during a 7-day interval after treatment with glucocorticoids (2.18; 95% CI: 1.02-4.66; P = 0.04). Neither administration of anthracyclines in the preceding 14 days nor neutropenia correlated with infections.

CONCLUSIONS

Serious infections in DS-ALL may present without typical signs such as fever. The immediate time period following administration of glucocorticoids is particularly associated with the risk of SIs.

The biology, pathogenesis and clinical aspects of acute lymphoblastic leukemia in children with Down syndrome

Children with Down syndrome (DS) are at a 20-fold increased risk for acute lymphoblastic leukemia (DS-ALL). Although the etiology of this higher risk of developing leukemia remains largely unclear, the recent identification of CRLF2 (cytokine receptor like factor 2) and JAK2 mutations and study of the effect of trisomy of Hmgn1 and Dyrk1a (dual-specificity tyrosine phosphorylation-regulated kinase 1A) on B-cell development have shed significant new light on the disease process. Here we focus on the clinical features, biology and genetics of ALL in children with DS. We review the unique characteristics of DS-ALL on both the clinical and molecular levels and discuss the differences in treatments and outcomes in ALL in children with DS compared with those without DS. The identification of new biological insights is expected to pave the way for novel targeted therapies.

Pharmacokinetics of Chemotherapeutic Drugs in Pediatric Patients With Down Syndrome and Leukemia

Children with Down syndrome (DS) have a 10- to 30-fold increased risk of developing acute myeloid leukemia or acute lymphoblastic leukemia. Patients with DS and leukemia are treated with the same chemotherapeutic agents as patients without DS. Treatment regimens for pediatric leukemia comprise multiple cytotoxic drugs including methotrexate, doxorubicin, vincristine, cytarabine, and etoposide. There have been reports of increased toxicity, as well as altered therapeutic outcomes in pediatric patients with DS and leukemia. This review is focused on the pharmacokinetics of cytotoxic drugs in pediatric patients with leukemia and DS. The available literature suggests that methotrexate and thioguanine display altered pharmacokinetic parameters in pediatric patients with DS. It has been hypothesized that the variable pharmacokinetics of these drugs may contribute to the increased incidence of treatment-related toxicities seen in DS. Data from a small number of studies suggest that the pharmacokinetics of vincristine, etoposide, doxorubicin, and busulfan are similar between patients with and without DS. Definitive conclusions regarding the pharmacokinetics of cytotoxic drugs in pediatric patients with leukemia and DS are difficult to reach due to limitations in the available studies.

Treatment-related toxicities in children with acute lymphoblastic leukaemia predisposition syndromes

Although most children with acute lymphoblastic leukaemia (ALL) do not harbor germline mutations that strongly predispose them to development of this malignancy, large syndrome registries and detailed mapping of exomes or whole genomes of familial leukaemia kindreds have revealed that 3-5% of all childhood ALL cases are due to such germline mutations, but the figure may be higher. Most of these syndromes are primarily characterized by their non-malignant phenotype, whereas ALL may be the dominating or even only striking manifestation of the syndrome in some families. Identification of such ALL patients is important in order to adjust therapy and offer genetic counseling and cancer surveillance to mutation carriers in the family. In the coming years large genomic screening projects are expected to reveal further hitherto unrecognised familial ALL syndromes. The treatment of ALL cases harboring cancer predisposing mutations can be challenging for both the physician and the patient due to their preexisting symptoms, their reduced tolerance to radio- and/or chemotherapy with enhanced risk of life-threatening organ toxicities, and the paucity of data from ALL patients with the same or similar syndromes being treated by contemporary protocols. Recent studies clearly indicate that many of these patients stand a good chance of cure, and that they should be offered chemotherapy with the intention to cure. Some of these syndromes are characterized by reduced tolerance to radiotherapy and/or specific anticancer agents, while others are not. This review summarises our current knowledge on the risk of acute toxicities for these ALL patients and provides guidance for treatment adjustments.

Pain in Intellectually Disabled Children: Towards Evidence-Based Pharmacotherapy?

This critical opinion article deals with the challenges of finding the most effective pharmacotherapeutic options for the management of pain in intellectually disabled children and provides recommendations for clinical practice and research. Intellectual disability can be caused by a wide variety of underlying diseases and may be associated with congenital anomalies such as cardiac defects, small-bowel obstructions or limb abnormalities as well as with comorbidities such as scoliosis, gastro-esophageal reflux disease, spasticity, and epilepsy. These conditions themselves or any necessary surgical interventions are sources of pain. Epilepsy often requires chronic pharmacological treatment with antiepileptic drugs. These antiepileptic drugs can potentially cause drug-drug interactions with analgesic drugs. It is unfortunate that children with intellectual disabilities often cannot communicate pain to caregivers. Although these children are at high risk of experiencing pain, researchers nevertheless often have to exclude them from trials on pain management because of ethical considerations. We therefore make a plea for prescribers, researchers, patient organizations, pharmaceutical companies, and policy makers to study evidence-based, safe and effective pharmacotherapy in these children through properly designed studies. In the meantime, parents and clinicians must resort to validated pain assessment tools such as the revised FLACC scale.

Developing population pharmacokinetic parameters for high-dose methotrexate therapy: implication of correlations among developed parameters for individual parameter estimation using the Bayesian least-squares method

Bayesian estimation enables the individual pharmacokinetic parameters of the medication administrated to be estimated using only a few blood concentrations. Due to wide inter-individual variability in the pharmacokinetics of methotrexate (MTX), the concentration of MTX needs to be frequently determined during high-dose MTX therapy in order to prevent toxic adverse events. To apply the benefits of Bayesian estimation to cases treated with this therapy, we attempted to develop an estimation method using the Bayesian least-squares method, which is commonly used for therapeutic monitoring in a clinical setting. Because this method hypothesizes independency among population pharmacokinetic parameters, we focused on correlations among population pharmacokinetic parameters used to estimate individual parameters. A two-compartment model adequately described the observed concentration of MTX. The individual pharmacokinetic parameters of MTX were estimated in 57 cases using the maximum likelihood method. Among the available parameters accounting for a 2-compartment model, V1, k10, k12, and k21 were found to be the combination showing the weakest correlations, which indicated that this combination was best suited to the Bayesian least-squares method. Using this combination of population pharmacokinetic parameters, Bayesian estimation provided an accurate estimation of individual parameters. In addition, we demonstrated that the degree of correlation among population pharmacokinetic parameters used in the estimation affected the precision of the estimates. This result highlights the necessity of assessing correlations among the population pharmacokinetic parameters used in the Bayesian least-squares method.

Hematopoietic stem cell transplantation for patients with acute lymphoblastic leukemia and Down syndrome

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is one curable option for high-risk acute lymphoblastic leukemia (ALL); however, transplant-related toxicities might be severe in patients with Down syndrome and ALL (DS-ALL).

PROCEDURE

HSCTs performed in patients with DS-ALL were identified in the Japan Society for Hematopoietic Cell Transplantation registry.

RESULTS

In the registry data, 11 patients with DS-ALL were identified. The median age at HSCT was 9 years (range: 6-22 years). Six patients underwent HSCT at non-remission status. Allogeneic grafts were utilized in all patients, including eight patients who received HSCT from unrelated donors. Reduced intensity conditioning regimens were used in three patients. All patients achieved neutrophil engraftment by a median of day 18 (range: day 11-61). Ten patients experienced grade 3 or more infectious episodes. Six patients experienced complications of the respiratory system. The incidences of II-IV or III-IV acute GVHD were nine (81.8%) or seven patients (63.6%), respectively. Chronic GVHD was observed in five (55.6%) out of nine evaluable patients. Seven patients died at a median of 6 months (range: 0-24 months) after HSCT. Two-year relapse-free and overall survival were 33.3% (95% CI: 2.5-64.1%) or 37.5% (95% CI: 5.9-69.1%), respectively. The causes of death were relapse (n = 2), infection (n = 2), bleeding (n = 1), thrombotic microangiopathy (n = 1), and chronic GVHD (n = 1).

CONCLUSIONS

Therapy-related mortality accounted for five out of seven deceased patients in this case series. Attempts to reduce toxicities should be considered in HSCT for patients with DS-ALL.

Genetic and metabolic determinants of methotrexate-induced mucositis in pediatric acute lymphoblastic leukemia

Methotrexate (MTX) is an effective and toxic chemotherapeutic drug in the treatment of pediatric acute lymphoblastic leukemia(ALL). In this prospective study, we aimed to identify metabolic and genetic determinants of MTX toxicity. One hundred and thirty-four Dutch pediatric ALL patients were treated with four high infusions MTX (HD-MTX: 5 g m(-2)) every other week according to the DCOG-ALL-10 protocol. Mucositis (National Cancer Institute grade ⩾ 3) was the most frequent occurring toxicity during the HD-MTX phase (20%) and occurred especially after the first MTX course. Mucositis was not associated with plasma MTX, plasma folate or plasma homocysteine levels. Patients with mucositis had higher erythrocyte folate levels at the start of protocol M than patients without mucositis (median 1.4 vs 1.2 μmol l(-1), P<0.008), this could reflect an increased MTX uptake in mucosal cells of patients with mucositis. From 17 single-nucleotide polymorphisms in the MTX pathway, only patients with the wild-type variant of rs7317112 SNP in the ABCC4 gene had more mucositis (AA (39%) vs AG/GG (15%), P=0.016). We found no evidence that erythrocyte folate levels mediate in the association between the rs7317112 and mucositis.

Child and adolescent Down syndrome-associated leukaemia: the Irish experience

BACKGROUND

Down syndrome (DS), the most common syndromic chromosomal abnormality is associated with a unique susceptibility to develop both acute myeloid (ML) and lymphoblastic leukaemia (ALL). These leukaemias differ from the non-DS-related types of leukaemia and are thought to be distinct biological entities.

AIMS

To perform a retrospective review of our experience of treating DS-related leukaemia at Our Lady's Children's Hospital.

METHODS

Data were extracted from a database established in 2000 to prospectively gather data on DS-associated leukaemias and their outcomes following polychemotherapy. Kaplan-Meier survival curves were constructed.

RESULTS

Nineteen patients with DS-ML were treated and 19 with DS-ALL. Sixteen (84%) patients with DS-ML are alive and in complete remission with a median follow-up of 7 years. All deaths in this cohort were due to treatment-related mortality (TRM). Of the DS-ALL patients, 12 (63%) remain alive with a median follow-up of 3.6 years. TRM accounted for five of the six deaths. One death was due to leukaemic relapse.

CONCLUSION

High cure rates are seen in DS-ML using contemporary polychemotherapy protocols, however, there is significant TRM in this cohort. DS-ALL does not have the same high cure rate as non-DS-ALL (>90%) and again this is mainly due to an excess of TRM.

Impact of oral mucositis on oral-health-related quality of life of patients diagnosed with cancer

INTRODUCTION

Oral mucositis (OM) has been described as the oral complication most frequently associated with antineoplastic therapy. However, the influence on the quality of life of affected patients is still unclear.

OBJECTIVE

To evaluate the impact of OM on the oral-health-related quality of life (OHRQoL) of patients diagnosed with cancer, who developed chemotherapy- and/or radiotherapy-induced OM.

METHODS

This is a cross-sectional evaluation of QoL using oral health impact profile-14 (OHIP-14). The study group comprised a sample of 60 patients diagnosed with cancer, who developed OM during the treatment. The instrument (OHIP-14) composed of seven dimensions was used: functional limitation, physical pain, psychological discomfort, physical deficiency, psychological deficiency, social incapacity, and deficiency.

RESULTS

The internal consistency of OHIP-14 measured by the Cronbach's α coefficient was of 0.76. Physical pain attained the highest score (worst quality of life) among the studied dimensions 60.8% (292/480), followed by physical limitation 52.7% (253/480), and psychological discomfort 50.8% (244/480). The dimension 'social limitation' obtained the lowest score 27.2% (131/480). There was statistically significant difference as regards gender (P = 0.021) for physical pain, with greater impact among patients of the male gender.

CONCLUSION

Oral-health-related quality of life is significantly affected by OM in individuals diagnosed with cancer.

Uptake carriers and oncology drug safety

Members of the solute carrier (SLC) family of transporters are responsible for the cellular influx of a broad range of endogenous compounds and xenobiotics in multiple tissues. Many of these transporters are highly expressed in the gastrointestinal tract, liver, and kidney and are considered to be of particular importance in governing drug absorption, elimination, and cellular sensitivity of specific organs to a wide variety of oncology drugs. Although the majority of studies on the interaction of oncology drugs with SLC have been restricted to the use of exploratory in vitro model systems, emerging evidence suggests that several SLCs, including OCT2 and OATP1B1, contribute to clinically important phenotypes associated with those agents. Recent literature has indicated that modulation of SLC activity may result in drug-drug interactions, and genetic polymorphisms in SLC genes have been described that can affect the handling of substrates. Alteration of SLC function by either of these mechanisms has been demonstrated to contribute to interindividual variability in the pharmacokinetics and toxicity associated with several oncology drugs. In this report, we provide an update on this rapidly emerging field.

Myelopathy mimicking subacute combined degeneration in a Down syndrome patient with methotrexate treatment for B lymphoblastic leukemia: report of an autopsy case

We report clinicopathological features of a 23-year-old woman with Down syndrome (DS) presenting with subacute myelopathy treated with chemotherapy, including intravenous and intrathecal administration of methotrexate (MTX), and with allogenic bone-marrow transplantation for B lymphoblastic leukemia. Autopsy revealed severe demyelinating vacuolar myelopathy in the posterior and lateral columns of the spinal cord, associated with macrophage infiltration, marked axonal loss and some swollen axons. Pathological changes of posterior and lateral columns were observed from the medulla oblongata to lumbar cord. Proximal anterior and posterior roots were preserved. Cerebral white matter was relatively well preserved. There were no vascular lesions or meningeal dissemination of leukemia. Longitudinal extension of cord lesions was extensive, unlike typical cases of subacute combined degeneration (SACD), but distribution of lesions and histological findings were similar to that of SACD. DS patients show heightened sensitivity to MTX because of their genetic background. Risk factors for toxic myelopathy of DS are discussed, including delayed clearance of MTX despite normal renal function, alterations in MTX polyglutamation and enhanced folic acid depletion due to gene dosage effects of chromosome 21. Alteration of folate metabolism and/or vitamin B12 levels through intravenous or intrathecal administration of MTX might exist, although vitamin B12 and other essential nutrients were managed using intravenous hyperalimentation. To the best of our knowledge, this is the first report of an autopsy case that shows myelopathy mimicking SACD in a DS patient accompanied by B lymphoblastic leukemia. The case suggests a pathophysiological mechanism of MTX-related myelopathy in DS patients with B lymphoblastic leukemia mimicking SACD.

Optimizing drug development of anti-cancer drugs in children using modelling and simulation

Modelling and simulation (M&S)-based approaches have been proposed to support paediatric drug development in order to design and analyze clinical studies efficiently. Development of anti-cancer drugs in the paediatric population is particularly challenging due to ethical and practical constraints. We aimed to review the application of M&S in the development of anti-cancer drugs in the paediatric population, and to identify where M&S-based approaches could provide additional support in paediatric drug development of anti-cancer drugs. A structured literature search on PubMed was performed. The majority of identified M&S-based studies aimed to use population PK modelling approaches to identify determinants of inter-individual variability, in order to optimize dosing regimens and to develop therapeutic drug monitoring strategies. Prospective applications of M&S approaches for PK-bridging studies have scarcely been reported for paediatric oncology. Based on recent developments of M&S in drug development there are several opportunities where M&S could support more informative bridging between children and adults, and increase efficiency of the design and analysis of paediatric clinical trials, which should ultimately lead to further optimization of drug treatment strategies in this population.

How I treat ALL in Down's syndrome: pathobiology and management

Children with Down syndrome are at high risk for developing B-cell precursor acute lymphoblastic leukemia (DS-ALL) associated with poor outcome due to both a high relapse rate and increased treatment-related mortality (TRM) from infections. Biologically, these heterogeneous leukemias are characterized by under-representation of the common cytogenetic subgroups of childhood ALL and overrepresentation of CRLF2-IL7R-JAK-STAT activating genetic aberrations. Although relapse is the major determinant of poor outcomes in this population, de-escalation of chemotherapy intensity might be feasible in the 10% to 15% DS-ALL patients with ETV6-RUNX1 or high hyperdipoidy in whom TRM is the major limiting event. As infection-associated TRM occurs during all treatment phases, including the maintenance period, increased surveillance and supportive care is required throughout therapy. Improvement in outcome will require better understanding of the causes of treatment failure and TRM, incorporation of new therapies targeting the unique biological properties of DS-ALL, and enhanced supportive care measures to reduce the risk of infection-related TRM. To facilitate these goals, an international collaboration plans to establish a prospective DS-ALL registry and develop specific supportive care recommendations for this at-risk population.

Acute lymphoblastic leukemia in children with Down syndrome: a retrospective analysis from the Ponte di Legno study group

Children with Down syndrome (DS) have an increased risk of B-cell precursor (BCP) acute lymphoblastic leukemia (ALL). The prognostic factors and outcome of DS-ALL patients treated in contemporary protocols are uncertain. We studied 653 DS-ALL patients enrolled in 16 international trials from 1995 to 2004. Non-DS BCP-ALL patients from the Dutch Child Oncology Group and Berlin-Frankfurt-Münster were reference cohorts. DS-ALL patients had a higher 8-year cumulative incidence of relapse (26% ± 2% vs 15% ± 1%, P < .001) and 2-year treatment-related mortality (TRM) (7% ± 1% vs 2.0% ± <1%, P < .0001) than non-DS patients, resulting in lower 8-year event-free survival (EFS) (64% ± 2% vs 81% ± 2%, P < .0001) and overall survival (74% ± 2% vs 89% ± 1%, P < .0001). Independent favorable prognostic factors include age <6 years (hazard ratio [HR] = 0.58, P = .002), white blood cell (WBC) count <10 × 10(9)/L (HR = 0.60, P = .005), and ETV6-RUNX1 (HR = 0.14, P = .006) for EFS and age (HR = 0.48, P < .001), ETV6-RUNX1 (HR = 0.1, P = .016) and high hyperdiploidy (HeH) (HR = 0.29, P = .04) for relapse-free survival. TRM was the major cause of death in ETV6-RUNX1 and HeH DS-ALLs. Thus, while relapse is the main contributor to poorer survival in DS-ALL, infection-associated TRM was increased in all protocol elements, unrelated to treatment phase or regimen. Future strategies to improve outcome in DS-ALL should include improved supportive care throughout therapy and reduction of therapy in newly identified good-prognosis subgroups.

Outcomes of treatment for relapsed acute lymphoblastic leukaemia in children with Down syndrome

Children with Down syndrome (DS) have a greater risk for developing both acute lymphoblastic leukaemia (ALL) and significant adverse effects of chemotherapy. We investigated their outcome with, and tolerance of, treatment protocols for relapsed ALL optimized in the paediatric population without DS. Probability of survival and causes of treatment failure were determined for 49 children with DS and a matched cohort of 98 children without DS among 2160 children treated for relapsed ALL in clinical trials conducted by the Berlin-Frankfurt-Münster ALL Relapse Study Group between 1983 and 2012. Despite more favourable ALL relapse characteristics, children with DS experienced lower event-free (EFS) and overall survival (OS) than the control group without DS (EFS 17 ± 08% vs. non-DS 41 ± 06%, P = 0·006; OS 17 ± 09% vs. non-DS 51 ± 06%, P < 0·001). Children with DS developed more frequently fatal complications of treatment (34 ± 07% vs. non-DS 10 ± 04%, P < 0·001). During the last decade, EFS and OS were no longer significantly different in children with and without DS (EFS 31 ± 09% vs. 36 ± 09%, P = 0·399; OS 31 ± 12% vs. 53 ± 09%, P = 0·151). DS proved an independent prognostic factor of outcome after ALL relapse. Induction deaths and treatment-related mortality but not subsequent relapse were the main barrier to successful outcomes of relapse therapy in children with DS.

Genome-wide study of methotrexate clearance replicates SLCO1B1

Methotrexate clearance can influence the cure of and toxicity in children with acute lymphoblastic leukemia (ALL). We estimated methotrexate plasma clearance for 1279 patients with ALL treated with methotrexate (24-hour infusion of a 1 g/m2 dose or 4-hour infusion of a 2 g/m2 dose) on the Children’s Oncology Group P9904 and P9905 protocols. Methotrexate clearance was lower in older children (P = 7 x 10(-7)), girls (P = 2.7 x 10(-4)), and those who received a delayed-intensification phase (P = .0022). A genome-wide analysis showed that methotrexate clearance was associated with polymorphisms in the organic anion transporter gene SLCO1B1 (P = 2.1 x 10(-11)). This replicates findings using different schedules of high-dose methotrexate in St Jude ALL treatment protocols; a combined meta-analysis yields a P value of 5.7 x 10(-19) for the association of methotrexate clearance with SLCO1B1 SNP rs4149056. Validation of this variant with 5 different treatment regimens of methotrexate solidifies the robustness of this pharmacogenomic determinant of methotrexate clearance. This study is registered at http://www.clinicaltrials.gov as NCT00005585 and NCT00005596.

Physicians compliance during maintenance therapy in children with Down syndrome and acute lymphoblastic leukemia

Children with Down syndrome (DS) and acute lymphoblastic leukemia (ALL) have an inferior prognosis compared with non-DS ALL patients. We reviewed methotrexate (MTX)/mercaptopurine (6MP) maintenance therapy data for children with DS treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL92 or the NOPHO ALL2000 protocols between 1992 and 2007. The 5-year event-free survival probability (pEFS(5 yr)) for the 66 DS patients was inferior to the 2602 non-DS patients (0.50 ± 0.07 vs 0.77 ± 0.01 (P<0.001)). The 48 DS patients in first remission at the beginning of maintenance therapy had pEFS(10 yr) below that of the 522 non-DS control patients (pEFS(10 yr): 0.58 (95% confidence interval (CI) 0.43-0.77) vs 0.83 (95% CI 0.80-0.86), respectively (P<0.0001)). The DS patients received lower median doses of MTX (median: 11.8 vs 15.4 (P<0.0001)) and 6MP (median: 43.6 vs 59.4 (P<0.0001)). In Cox regression analysis, male gender, presence of DS and high median maintenance therapy white blood cell levels (mWBC) were associated with increased risk for relapse. DS-ALL patients with mWBC above or below 3.5 × 10(9)/l (protocol target) had pEFS(10 yr) of 0.31 and 0.72 (P=0.02), and the mWBC hazard ratio for DS-ALL patients was 2.0 (P<0.0005). We conclude that insufficient treatment intensity during maintenance therapy of DS-ALL patients may contribute to their poor prognosis.

Contribution of tumoral and host solute carriers to clinical drug response

Members of the solute carrier family of transporters are responsible for the cellular uptake of a broad range of endogenous compounds and xenobiotics in multiple tissues. Several of these solute carriers are known to be expressed in cancer cells or cancer cell lines, and decreased cellular uptake of drugs potentially contributes to the development of resistance. As result, the expression levels of these proteins in humans have important consequences for an individual's susceptibility to certain drug-induced side effects, interactions, and treatment efficacy. In this review article, we provide an update of this rapidly emerging field, with specific emphasis on the direct contribution of solute carriers to anticancer drug uptake in tumors, the role of these carriers in regulation of anticancer drug disposition, and recent advances in attempts to evaluate these proteins as therapeutic targets.

Influence of folate pathway polymorphisms on high-dose methotrexate-related toxicity and survival in childhood acute lymphoblastic leukemia

The prediction of high-dose methotrexate (HD-MTX) toxicity is a key issue in the individualization of treatment in childhood acute lymphoblastic leukemia (ALL). Our aim was to evaluate the influence of MTX pathway polymorphisms on HD-MTX treatment outcome in children with ALL. In total, 167 children with ALL were genotyped for methylenetetrahydrofolate dehydrogenase (MTHFD1) 1958G > A, methylenetetrahydrofolate reductase (MTHFR) 677C > T and 1298A > C and thymidylate synthase (TYMS) 2R > 3R polymorphisms. The MTHFD1 1958A allele significantly reduced the odds of hepatotoxicity (adjusted p = 0.009), while the TYMS 3R allele significantly reduced the odds of leukocytopenia and thrombocytopenia (adjusted p = 0.005 and adjusted p = 0.002, respectively). MTHFR polymorphisms did not influence HD-MTX-related toxicity, but a significant effect of MTHFR 677C > T-TYMS 2R > 3R and MTHFD1 1958G > A-MTHFR 677C > T interactions on HD-MTX-related toxicity was observed. None of the investigated polymorphisms influenced survival. Our study suggests an important role of polymorphisms and gene-gene interactions within the folate pathway in HD-MTX-related toxicity in childhood ALL.

[Pharmacokinetic analysis of high-dose methotrexate treatments in children with hematologic malignancies]

Monitoring the pharmacokinetic parameters of different anticancer drugs is necessary because they might have several side effects.

AIM

Pharmacokinetic and toxicity evaluation of high-dose methotrexate treatments in children with acute lymphoblastic leukemia.

PATIENTS AND METHODS

43 children (28 boys, 15 girls, mean age: 7.03 years) in 147 cases were treated with 5 g/m2/24h MTX according to ALL-BFM 1995 and 2002 protocols. Methotrexate and 7-hydroxi-methotrexate levels were measured with high pressure liquid chromatography at 24, 36, 48 hours. Authors registered the development of hepatotoxicity, nephrotoxicity, grade III/IV oral mucositis.

RESULTS

Therapeutic methotrexate serum concentrations (30-100µmol/l) were achieved in 72.5% of the cases. Repeated treatments resulted similar serum levels. Hepatotoxicity and hypoproteinemia occurred in 17% and in 48.9% of the cases. There was significant correlation between serum 7-hydroxi-methotrexate and creatinine levels (p<0.05).

CONCLUSION

5 g/m2 methotrexate resulted reliable therapeutic serum levels with mild and reversible toxicity. 7-hydroxi-methotexate measurements might be more useful than methotrexate levels to detect toxicity.