Pharmacokinetics of PEGasparaginase in Infants with Acute Lymphoblastic Leukemia.

BACKGROUND: PEGasparaginase is known to be a critical drug for treating pediatric acute lymphoblastic leukemia (ALL), however, there is insufficient evidence to determine the optimal dose for infants who are less than one year of age at diagnosis. This international study was conducted to identify the pharmacokinetics of PEGasparaginase in infants with newly diagnosed ALL and gather insight into the clearance and dosing of this population. METHODS: Infants with ALL who received treatment with PEGasparaginase were included in our population pharmacokinetic assessment employing non-linear mixed effects modelling (NONMEM). RESULTS: 68 infants with ALL, with a total of 388 asparaginase activity samples, were included. PEGasparaginase doses ranging from 400 to 3,663 IU/m2 were administered either intravenously or intramuscularly. A one-compartment model with time-dependent clearance, modeled using a transit model, provided the best fit to the data. Body weight was significantly correlated with clearance and volume of distribution. The final model estimated a half-life of 11.7 days just after administration, which decreased to 1.8 days 14 days after administration. Clearance was 19.5% lower during the post-induction treatment phase compared to induction. CONCLUSION: The pharmacokinetics of PEGasparaginase in infants diagnosed under one year of age with ALL is comparable to that of older children (1-18 years). We recommend a PEGasparaginase dosing at 1,500 IU/m2 for infants without dose adaptations according to age, and implementing therapeutic drug monitoring as standard practice.

Epidemiological Study of Malignant Paediatric Liver Tumours in Denmark 1985-2020.

BACKGROUND: Malignant liver tumours in children are rare and national outcomes for this tumour entity are rarely published. This study mapped paediatric liver tumours in Denmark over 35 years and reported on the incidence, outcomes and long-term adverse events. METHODS: We identified all liver tumours from the Danish Childhood Cancer Registry and reviewed the case records for patient and tumour characteristics, treatment and clinical outcome. RESULTS: We included 79 patients in the analyses. Overall crude incidence was ~2.29 per 1 million children (<15 yr) per year, with 61 hepatoblastomas (HB), 9 hepatocellular carcinomas and 9 other hepatic tumours. Overall 5-year survival was 84%, 78% and 44%, respectively. Nine patients had underlying liver disease or predisposition syndrome. Seventeen children underwent liver transplantation, with two late complications, biliary stenosis and liver fibrosis. For HB, age ≥ 8 years and diagnosis prior to 2000 were significant predictors of a poorer outcome. Adverse events included reduced renal function in 10%, reduced cardiac function in 6% and impaired hearing function in 60% (19% needed hearing aids). Behavioural conditions requiring additional support in school were registered in 10 children. CONCLUSIONS: In Denmark, incidences of malignant liver tumours during the last four decades have been increasing, as reported in the literature. HB survival has improved since the year 2000 and is comparable with international results. Reduced hearing is the major treatment-related side effect and affects approximately 60% of patients.

PEG-asparaginase treatment regimens for acute lymphoblastic leukaemia in children: a network meta-analysis.

BACKGROUND: Asparaginase has played a crucial role in the improvement of survival in children with acute lymphoblastic leukaemia (ALL), which is the commonest cancer among children. Survival rates have steadily increased over decades since the introduction of asparaginase to ALL therapy, and overall survival rates reach 90% with the best contemporary protocols. Currently, polyethylene glycolated native Escherichia coli-derived L-asparaginase (PEG-asparaginase) is the preferred first-line asparaginase preparation. Besides its clinical benefits, PEG-asparaginase is well known for severe toxicities. Agreement on the optimal dose, treatment duration, and frequency of administration has never been reached among clinicians. OBJECTIVES: Primary objective To assess the effect of the number of PEG-asparaginase doses on survival and relapse in children and adolescents with ALL. Secondary objectives To assess the association between the number of doses of PEG-asparaginase and asparaginase-associated toxicities (e.g. hypersensitivity, thromboembolism, pancreatitis and osteonecrosis). To undertake a network meta-analysis at dose-level in order to generate rankings of the number of doses of PEG-asparaginase used in the treatment for ALL, according to their benefits (survival and relapse) and harms (toxicity). SEARCH METHODS: We searched CENTRAL, PubMed, Embase, Web of Science databases and three trials registers in November 2021, together with reference checking, citation searching and contact with study authors to identify additional studies. SELECTION CRITERIA: We included randomised controlled trials (RCTs) comparing different PEG-asparaginase treatment regimens in children and adolescents (< 18 years of age) with first-line ALL treated with multiagent chemotherapy including PEG-asparaginase. DATA COLLECTION AND ANALYSIS: Using a standardised data collection form, two review authors independently screened and selected studies, extracted data, assessed risk of bias for each outcome using a standardised tool (RoB 2.0) and assessed the certainty of evidence for each outcome using the GRADE approach. Primary outcomes included overall survival, event-free survival and leukaemic relapse. Secondary outcomes included asparaginase-associated toxicities (hypersensitivity, thromboembolism, pancreatitis, sinusoidal obstruction syndrome and osteonecrosis as well as overall asparaginase-associated toxicity). We conducted the review and performed the analyses in accordance with the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions. MAIN RESULTS: We included three RCTs in the review, and identified an additional four ongoing studies. We judged outcomes of two RCTs to be at low risk of bias in all the Cochrane risk of bias (RoB 2) domains. We rated the remaining study as having some concerns regarding bias. Due to concerns about imprecision, we rated all outcomes as having low- to moderate-certainty evidence.  One study compared intermittent PEG-asparaginase treatment (eight doses of PEG-asparaginase, 1000 IU/m2, intramuscular (IM) administration) versus continuous PEG-asparaginase treatment (15 doses of PEG-asparaginase, 1000 IU/m2, IM) in 625 participants with non-high risk ALL aged 1.0 to 17.9 years. We found that treatment with eight doses probably results in little to no difference in event-free survival compared to treatment with 15 doses (RR 1.01, 95% CI 0.97 to 1.06; moderate-certainty evidence). Compared to treatment with 15 doses, treatment with eight doses may result in either no difference or a slight reduction in hypersensitivity (RR 0.64, 95% CI 0.21 to 1.93; low-certainty evidence), thromboembolism (RR 0.55, 95% CI 0.22 to 1.36; low-certainty evidence) or osteonecrosis (RR 0.68, 95% CI 0.35 to 1.32; low-certainty evidence). Furthermore, we found that treatment with eight doses probably reduces pancreatitis (RR 0.31, 95% CI 0.12 to 0.75; moderate-certainty evidence) and asparaginase-associated toxicity (RR 0.53, 95% CI 0.35 to 0.78; moderate-certainty evidence) compared to treatment with 15 doses. One study compared low-risk standard treatment with additional PEG-asparaginase (six doses, 2500 IU/m2, IM) versus low-risk standard treatment (two doses, 2500 IU/m2, IM) in 1857 participants aged one to nine years old with standard low-risk ALL. We found that, compared to treatment with two doses, treatment with six doses probably results in little to no difference in overall survival (RR 0.99, 95% CI 0.98 to 1.00; moderate-certainty evidence) and event-free survival (RR 1.01, 95% CI 0.99 to 1.04; moderate-certainty evidence), and may result in either no difference or a slight increase in osteonecrosis (RR 1.65, 95% CI 0.91 to 3.00; low-certainty evidence). Furthermore, we found that treatment with six doses probably increases hypersensitivity (RR 12.05, 95% CI 5.27 to 27.58; moderate-certainty evidence), pancreatitis (RR 4.84, 95% CI 2.15 to 10.85; moderate-certainty evidence) and asparaginase-associated toxicity (RR 4.49, 95% CI 3.05 to 6.59; moderate-certainty evidence) compared to treatment with two doses. One trial compared calaspargase (11 doses, 2500 IU/m2, intravenous (IV)) versus PEG-asparaginase (16 doses, 2500 IU/m2, IV) in 239 participants aged one to 21 years with standard- and high-risk ALL and lymphoblastic lymphoma. We found that treatment with 11 doses of calaspargase probably results in little to no difference in event-free survival compared to treatment with 16 doses of PEG-asparaginase (RR 1.06, 95% CI 0.97 to 1.16; moderate-certainty evidence). However, treatment with 11 doses of calaspargase probably reduces leukaemic relapse compared to treatment with 16 doses of PEG-asparaginase (RR 0.32, 95% CI 0.12 to 0.83; moderate-certainty evidence). Furthermore, we found that treatment with 11 doses of calaspargase results in either no difference or a slight reduction in hypersensitivity (RR 1.17, 95% CI 0.64 to 2.13; low-certainty evidence), pancreatitis (RR 0.85, 95% CI 0.47 to 1.52; low-certainty evidence), thromboembolism (RR 0.83, 95% CI 0.48 to 1.42; low-certainty evidence), osteonecrosis (RR 0.63, 95% CI 0.15 to 2.56; low-certainty evidence) and asparaginase-associated toxicity (RR 1.00, 95% CI 0.71 to 1.40; low-certainty evidence) compared to treatment with 16 doses of PEG-asparaginase. AUTHORS' CONCLUSIONS: We were not able to conduct a network meta-analysis, and could not draw clear conclusions because it was not possible to rank the interventions. Overall, we found that different numbers of doses of PEG-asparaginase probably result in little to no difference in event-free survival across all studies. In two studies, we found that a higher number of PEG-asparaginase doses probably increases pancreatitis and asparaginase-associated toxicities.

Can Machine Learning Models Predict Asparaginase-associated Pancreatitis in Childhood Acute Lymphoblastic Leukemia.

Asparaginase-associated pancreatitis (AAP) frequently affects children treated for acute lymphoblastic leukemia (ALL) causing severe acute and persisting complications. Known risk factors such as asparaginase dosing, older age and single nucleotide polymorphisms (SNPs) have insufficient odds ratios to allow personalized asparaginase therapy. In this study, we explored machine learning strategies for prediction of individual AAP risk. We integrated information on age, sex, and SNPs based on Illumina Omni2.5exome-8 arrays of patients with childhood ALL (N=1564, 244 with AAP 1.0 to 17.9 yo) from 10 international ALL consortia into machine learning models including regression, random forest, AdaBoost and artificial neural networks. A model with only age and sex had area under the receiver operating characteristic curve (ROC-AUC) of 0.62. Inclusion of 6 pancreatitis candidate gene SNPs or 4 validated pancreatitis SNPs boosted ROC-AUC somewhat (0.67) while 30 SNPs, identified through our AAP genome-wide association study cohort, boosted performance (0.80). Most predictive features included rs10273639 (PRSS1-PRSS2), rs10436957 (CTRC), rs13228878 (PRSS1/PRSS2), rs1505495 (GALNTL6), rs4655107 (EPHB2) and age (1 to 7 y). Second AAP following asparaginase re-exposure was predicted with ROC-AUC: 0.65. The machine learning models assist individual-level risk assessment of AAP for future prevention trials, and may legitimize asparaginase re-exposure when AAP risk is predicted to be low.

Bloodstream Infections in Children With Cancer: Pathogen Distribution and Antimicrobial Susceptibility Patterns Over a 10-Year Period.

Bloodstream infections (BSIs) adversely affect clinical outcome in children with cancer. Over 1 decade, this retrospective cohort study describes pathogen distribution in BSIs and antimicrobial susceptibility against empirical antibiotics frequently prescribed in children with cancer. The antibiotic efficacy was evaluated through the determination of minimal inhibitory concentrations for piperacillin-tazobactam and meropenem and by disk diffusion for remaining antibiotics. From 2004 to 2013, 398 BSIs occurred in 196 children with cancer (median age: 5.4 y), resulting in 457 bacteria. Overall, 266 (58.2%) were Gram-positive, and 191 (41.8%) were Gram-negative with a significant Gram-positive increase over time (P=0.032). Coagulase-negative staphylococci (74, 16.2%), viridans group streptococci (67, 14.7%), Escherichia coli (52, 11.4%), and Staphylococcus aureus (39, 8.5%) were the most common pathogens. Susceptibility to piperacillin-tazobactam (95.9%, P=0.419) and meropenem (98.9%, P=0.752) was stable over time, and resistance was observed among viridans group streptococci against piperacillin-tazobactam (18%) and meropenem (7%) and among Enterobacterales against piperacillin-tazobactam (3%). Vancomycin showed 98% Gram-positive activity, gentamicin 82% Gram-negative activity and ampicillin, cefotaxime, and cefuroxime were active in 50%, 72%, and 69% of pathogens, respectively, and BSI-related mortality was 0%. In conclusion, over 1 decade, we report an increase in Gram-positive BSIs, and stable, low-resistance rates against currently recommended empirical antibiotics, piperacillin-tazobactam and meropenem.

Continuous infusion of piperacillin-tazobactam significantly improves target attainment in children with cancer and fever.

BACKGROUND: Children with febrile neutropenia commonly exhibit alterations of pharmacokinetic (PK) parameters, leading to decreased ß-lactam concentrations. AIMS: This study evaluated piperacillin PK and probability of target attainment (PTA) with continuous infusion of piperacillin-tazobactam, in order to optimize the dosing regimen. METHODS: This prospective PK study included children with cancer, aged 1-17 years, who were treated with piperacillin-tazobactam for suspected or verified infection. A piperacillin-tazobactam loading dose (100 mg/kg) was administered followed by continuous infusion (300 mg/kg/day). The unbound fraction of piperacillin was quantified by high-performance liquid chromatography and PK were described using population PK modeling. PK data was used to update and extend a previous PK model built on data following intermittent administration. Monte Carlo simulations were performed to assess PTA for targets of 100% time above the minimum inhibitory concentration (100% fT > MIC) and 50% fT > 4xMIC. RESULTS: We included 68 fever episodes among 38 children with a median (IQR) age of 6.5 years and body weight of 27.4 kg (15.1-54.0). A three-compartment model adequately described the concentration-time data. Median (95% confidence interval) estimates for clearance and piperacillin concentration at steady state were 14.2 L/h/70 kg (13.0; 15.3) and 47.6 mg/L (17.2; 129.5), respectively. Body weight or lean body weight was significantly associated with the PK parameters, and body weight was integrated in the final PK model. Based on piperacillin exposure, continuous infusion was the only dosing regimen to achieve optimal PTA for the P. aeruginosa breakpoint (16 mg/L) with the target of 100% fT > MIC, and a daily dose of 300 mg/kg reached optimal PTA. The strict target of 50% fT > 4xMIC (64 mg/L) was not feasibly attained by any dosing regimen at recommended doses. CONCLUSION: Unlike conventional piperacillin intermittent administration and extended infusion regimens, continuous infusion allows the target of 100% fT > MIC to be reached for children with febrile neutropenia.

Hypersensitivity to Pegylated E.coli asparaginase as first-line treatment in contemporary paediatric acute lymphoblastic leukaemia protocols: a meta-analysis of the Ponte di Legno Toxicity working group.

BACKGROUND: Hypersensitivity reactions to asparaginase challenge its use and occur frequently (30-75%) after native Escherichia Coli (E.coli) asparaginase. Comparison of incidence of allergic reactions to pegylated E.coli asparaginase (PEGasparaginase) across contemporary paediatric acute lymphoblastic leukaemia (ALL) protocols is lacking. METHOD AND PATIENTS: Questionnaires were sent to all members of the international ALL Ponte di Legno Toxicity Working Group. Meta-analyses were conducted to estimate the incidence of three types of hypersensitivity (allergy, allergic-like reaction and silent inactivation). Information on protocol level regarding PEGasparaginase dosing regimen, administration route and use of therapeutic drug monitoring was collected for risk analysis. RESULTS: Newly diagnosed patients with ALL (n = 5880), aged 1-24 years old, were enrolled in seven different upfront ALL protocols using PEGasparaginase as first-line treatment. The incidence of allergic reactions (sum of allergies and allergic-like reactions) [95% confidence interval] was 2% [1%; 3%] during induction and 8% [5%; 11%] during postinduction. Route of administration, number of doses, dosage and number of PEGasparaginase-free weeks did not significantly influence risk of hypersensitivity. Multivariate meta-regression analysis suggests that initiation of PEGasparaginase in postinduction and higher number of PEGasparaginase-free intervals increased the risk for allergic reactions. 9-16% and 23-29% of all hypersensitivities were allergic-like reactions and silent inactivation, respectively. CONCLUSION: The incidence of allergic reactions is lower in protocols using PEGasparaginase as first-line treatment compared with that reported for E.coli asparaginase or PEGasparaginase after E.coli asparaginase. Postinduction phase, a higher number of PEGasparaginase-free intervals, and initiation of PEGasparaginase in postinduction phase are risk factors for allergic reactions. These results are important for planning of PEGasparaginase administrations in future frontline therapy.

Detection mode of childhood acute lymphoblastic leukaemia relapse and its effect on survival: a Nordic population-based cohort study.

Relapse constitutes the greatest threat to event-free survival after completion of treatment for childhood acute lymphoblastic leukaemia (ALL). However, evidence on optimal follow-up schedules is limited. The aims of the present population-based cohort study were to assess the value of current follow-up schedules after completion of Nordic Society of Paediatric Haematology and Oncology ALL protocol treatment and to estimate the impact of relapse detection mode on overall survival (OS). Among 3262 patients diagnosed between 1992 and 2014 and who completed treatment, 338 developed a relapse. Relapse detection was equally distributed between extra visits (50·8%) and scheduled follow-up visits (49·2%). All cases detected at an extra visit and 64·3% of cases detected at a scheduled visit presented with symptoms or objective findings. Neither the mode of detection {adjusted hazard ratio 0·95, [95% confidence interval (CI) 0·61-1·48] for scheduled visits} nor the duration of symptoms was an independent risk factor for OS after relapse. The estimated number of scheduled blood samples needed to diagnose one subclinical relapse during the first 5 years after treatment cessation was 1269 (95% CI 902-1637). In conclusion, based on OS data, scheduled visits after cessation of therapy seem to yield no extra benefit. These results should frame future follow-up strategies.

Asparaginase-Associated Pancreatitis in Acute Lymphoblastic Leukemia: Results From the NOPHO ALL2008 Treatment of Patients 1-45 Years of Age.

PURPOSE: Asparaginase-associated pancreatitis (AAP) is common in patients with acute lymphoblastic leukemia (ALL), but risk differences across age groups both in relation to first-time AAP and after asparaginase re-exposure have not been explored. PATIENTS AND METHODS: We prospectively registered AAP (n = 168) during treatment of 2,448 consecutive ALL patients aged 1.0-45.9 years diagnosed from July 2008 to October 2018 and treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol. RESULTS: Compared with patients aged 1.0-9.9 years, adjusted AAP hazard ratios (HRa) were associated with higher age with almost identical HRa (1.6; 95% CI, 1.1 to 2.3; P = .02) for adolescents (10.0-17.9 years) and adults (18.0-45.9 years). The day 280 cumulative incidences of AAP were 7.0% for children (1.0-9.9 years: 95% CI, 5.4 to 8.6), 10.1% for adolescents (10.0 to 17.9 years: 95% CI, 7.0 to 13.3), and 11.0% for adults (18.0-45.9 years: 95% CI, 7.1 to 14.9; P = .03). Adolescents had increased odds of both acute (odds ratio [OR], 5.2; 95% CI, 2.1 to 13.2; P = .0005) and persisting complications (OR, 6.7; 95% CI, 2.4 to 18.4; P = .0002) compared with children (1.0-9.9 years), whereas adults had increased odds of only persisting complications (OR, 4.1; 95% CI, 1.4 to 11.8; P = .01). Fifteen of 34 asparaginase-rechallenged patients developed a second AAP. Asparaginase was truncated in 17/21 patients with AAP who subsequently developed leukemic relapse, but neither AAP nor the asparaginase truncation was associated with increased risk of relapse. CONCLUSION: Older children and adults had similar AAP risk, whereas morbidity was most pronounced among adolescents. Asparaginase re-exposure should be considered only for patients with an anticipated high risk of leukemic relapse, because multiple studies strongly indicate that reduction of asparaginase treatment intensity increases the risk of relapse.

Genetic predisposition to PEG-asparaginase hypersensitivity in children treated according to NOPHO ALL2008.

Asparaginase is essential in childhood acute lymphoblastic leukaemia (ALL) treatment, however hypersensitivity reactions to pegylated asparaginase (PEG-asparaginase) hampers anti-neoplastic efficacy. Patients with PEG-asparaginase hypersensitivity have been shown to possess zero asparaginase enzyme activity. Using this measurement to define the phenotype, we investigated genetic predisposition to PEG-asparaginase hypersensitivity in a genome-wide association study (GWAS). From July 2008 to March 2016, 1494 children were treated on the Nordic Society of Paediatric Haematology and Oncology ALL2008 protocol. Cases were defined by clinical hypersensitivity and no enzyme activity, controls had enzyme activity ≥ 100 iu/l and no hypersensitivity symptoms. PEG-asparaginase hypersensitivity was reported in 13·8% (206/1494) of patients. Fifty-nine cases and 772 controls fulfilled GWAS inclusion criteria. The CNOT3 variant rs73062673 on 19q13.42, was associated with PEG-asparaginase allergy (P = 4·68 × 10-8 ). We further identified two signals on chromosome 6 in relation to HLA-DQA1 (P = 9·37 × 10-6 ) and TAP2 (P = 1·59 × 10-5 ). This study associated variants in CNOT3 and in the human leucocyte antigen (HLA) region with PEG-asparaginase hypersensitivity, suggesting that not only genetic variations in the HLA region, but also regulation of these genes are of importance in the biology of this toxicity. Furthermore, our study emphasizes the importance of using asparaginase enzyme activity measurements to identify PEG-asparaginase hypersensitivity.

Hepatic sinusoidal obstruction syndrome during maintenance therapy of childhood acute lymphoblastic leukemia is associated with continuous asparaginase therapy and mercaptopurine metabolites.

BACKGROUND: Hepatic sinusoidal obstruction syndrome (SOS) during treatment of childhood acute lymphoblastic leukemia (ALL) has mainly been associated with 6-thioguanine. The occurrence of several SOS cases after the introduction of extended pegylated asparaginase (PEG-asparaginase) therapy in the Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol led us to hypothesize that PEG-asparaginase, combined with other drugs, may trigger SOS during 6-thioguanine-free maintenance therapy. PROCEDURE: In children with ALL treated in Denmark according to the NOPHO ALL2008 protocol, we investigated the risk of SOS during methotrexate (MTX)/6-mercaptopurine (6MP) maintenance therapy that included PEG-asparaginase until week 33 (randomized to two- vs. six-week intervals), as well as alternating high-dose MTX or vincristine/dexamethasone pulses every four weeks. RESULTS: Among 130 children receiving PEG-asparaginase biweekly, 29 developed SOS (≥2 criteria: hyperbilirubinemia, hepatomegaly, ascites, weight gain ≥2.5%, unexplained thrombocytopenia <75 × 109 l-1 ) at a median of 30 days (interquartile range [IQR]: 17-66) into maintenance (cumulative incidence: 27%). SOS cases fulfilling one, two, or three Ponte di Legno criteria were classified as possible (n = 2), probable (n = 8), or verified (n = 19) SOS, respectively. Twenty-six cases (90%) occurred during PEG-asparaginase treatment, including 21 (81%) within 14 days from the last chemotherapy pulse compared with the subsequent 14 days (P = 0.0025). Cytotoxic 6MP metabolites were significantly higher on PEG-asparaginase compared to after its discontinuation. Time-dependent Cox regression analysis showed increased SOS hazard ratio (HR) for erythrocyte levels of methylated 6MP metabolites (HR: 1.09 per 1,000 nmol/mmol hemoglobin increase, 95% confidence interval: 1.05-1.14). Six-week PEG-asparaginase intervals significantly reduced SOS-specific hazards (P < 0.01). CONCLUSIONS: PEG-asparaginase increases cytotoxic 6MP metabolite levels and risk of SOS, potentially interacting with other chemotherapy pulses.

Leukemic blasts are present at low levels in spinal fluid in one-third of childhood acute lymphoblastic leukemia cases.

BACKGROUND: Central nervous system (CNS) involvement is associated with relapse in childhood acute lymphoblastic leukemia (ALL) and is a diagnostic challenge. PROCEDURE: In a Nordic/Baltic prospective study, we assessed centralized flow cytometry (FCM) of locally fixed cerebrospinal fluid (CSF) samples versus local conventional cytospin-based cytology (CC) for detecting leukemic cells and evaluating kinetics of elimination of leukemic cells in CSF. RESULTS: Among 300 patients with newly diagnosed ALL, 87 (29%) had CSF involvement by FCM, while CC was positive in 30 (10%) of 299 patients with available CC data (P < 0.001). Patients with FCM+/CC+ had higher CSF leukemic blast counts compared to patients positive by FCM only (medians: 0.10 vs. 0.017 leukemic blasts/µl, P = 0.006). Patients positive by FCM had higher white blood cell counts in peripheral blood than patients negative by FCM (medians: 45 × 10(9) /l vs. 10 × 10(9) /l, P < 0.001), were younger (medians: 3 years vs. 4 years, P = 0.03), and more frequently had T-cell ALL (18/87 vs. 16/213, P = 0.001). At treatment day 15, five of 52 patients (10%) who had CSF positive by FCM at diagnosis remained so despite at least two doses of weekly intrathecal chemotherapy. CONCLUSIONS: Longer follow-up is needed to clarify whether FCM positivity has prognostic significance and is an indicator for intensified CNS-directed therapy.

Cerebral sinus venous thromboses in children with acute lymphoblastic leukaemia - a multicentre study from the Nordic Society of Paediatric Haematology and Oncology.

We present a prospective multicentre cohort of 20 children with acute lymphoblastic leukaemia (ALL) and cerebral sinus venous thrombosis (CSVT). The study covers a period of 5 years and comprises 1038 children treated according to the Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL 2008 protocol. The cumulative incidence of CSVT was 2%. Sixteen of the thromboses were related to asparaginase and 16 to steroids. Most CSVTs occurred in the consolidation phase. Nearly all were treated with low molecular weight heparin without bleeding complications. Mortality related to CSVT directly or indirectly was 10%, emphasizing the importance of this complication.

Cerebrospinal fluid asparagine depletion during pegylated asparaginase therapy in children with acute lymphoblastic leukaemia.

L-asparaginase is an important drug in the treatment of childhood acute lymphoblastic leukaemia (ALL). Cerebrospinal fluid (CSF) asparagine depletion is considered a marker of asparaginase effect in the central nervous system (CNS) and may play a role in CNS-directed anti-leukaemia therapy. The objective of this study was to describe CSF asparagine depletion during 30 weeks of pegylated asparaginase therapy, 1000 iu/m(2) i.m. every second week, and to correlate CSF asparagine concentration with serum L-asparaginase enzyme activity. Danish children (1-17 years) with ALL, treated according to the Nordic Society of Paediatric Haematology and Oncology ALL2008 protocol, standard and intermediate risk, were included. CSF samples were obtained throughout L-asparaginase treatment at every scheduled lumbar puncture. A total of 128 samples from 31 patients were available for analysis. Median CSF asparagine concentration decreased from a pre-treatment level of 5·3 µmol/l to median levels ≤1·5 µmol/l. However, only 4/31 patients (five samples) had CSF asparagine concentrations below the limit of detection (0·1 µmol/l). In 11 patients, 24 paired same day serum and CSF samples were obtained. A decrease in CSF asparagine corresponded to serum enzyme activities above 50 iu/l. Higher serum enzyme activities were not followed by more extensive depletion. In conclusion, pegylated asparaginase 1000 iu/m(2) i.m. every second week effectively reduced CSF asparagine levels.

Asparaginase-associated pancreatitis in children with acute lymphoblastic leukaemia in the NOPHO ALL2008 protocol.

L-asparaginase is an important drug in the treatment of childhood acute lymphoblastic leukaemia (ALL). Treatment is associated with several toxicities, including acute pancreatitis. Clinical course, presentation, re-exposure to L-asparginase after pancreatitis and risk of recurrent pancreatitis within an asparaginase-intensive protocol has been poorly reported. Children (1-17 years) on the ongoing Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol with asparaginase-associated pancreatitis (AAP) diagnosed between 2008 and 2012 were identified through the online NOPHO ALL toxicity registry. NOPHO ALL2008 includes eight or 15 doses of intramuscular pegylated L-asparginase (PEG-asparaginase) 1000 iu/m(2) /dose at 2-6 weeks intervals, with a total of 30 weeks of exposure to PEG-asparaginase (clinicaltrials.gov no: NCT00819351). Of 786 children, 45 were diagnosed with AAP with a cumulative risk of AAP of 5·9%. AAP occurred after a median of five doses (range 1-13), and 11 d (median) from the latest administration of PEG-Asparaginase. Thirteen patients developed pseudocysts (30%) and 11 patients developed necrosis (25%). One patient died from pancreatitis. Twelve AAP patients were re-exposed to L-asparginase, two of whom developed mild AAP once more, after four and six doses respectively. In conclusion, re-exposure to PEG-asparaginase in ALL patients with mild AAP seems safe.