Search

BACKGROUND: Children with febrile neutropenia commonly exhibit alterations of pharmacokinetic (PK) parameters, leading to decreased β-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.

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.

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.

ObjectiveDistinction on clinical grounds between acute lymphoblastic leukaemia presenting with arthropathy (ALLarthropathy) and juvenile idiopathic arthritis (JIA) is difficult, as the clinical and paraclinical signs of leukaemia may be vague. The primary aim was to examine the use of lectin complement pathway proteins as markers to differentiate ALLarthropathy from JIA. The secondary aims were to compare the protein levels at baseline and follow-up in a paired number of children with ALL and to examine the correlation with haematology counts, erythrocyte sedimentation reaction (ESR), C-reactive protein (CRP), blasts, relapse and death.Study designIn this observational study, we measured M-ficolin, CL-K1 and MASP-3 in serum from children with ALL (n=151) and JIA (n=238) by time-resolved immunofluorometric assays. Logistic regression was used for predictions of ALL risk, considering the markers as the respective exposures. We performed internal validation using repeated ‘10-fold cross-validation’ with 100 repetitions computing the area under the curve (AUC) as well as positive and negative predictive values in order to evaluate the predictive performance.ResultsThe level of M-ficolin was higher in JIA than ALLtotal and the ALLarthropathy subgroup. The M-ficolin level normalised after remission of ALL. M-ficolin could differentiate ALL from JIA with an AUC of 94% and positive predictive value (PPV) of 95%, exceeding CRP and haemoglobin. In a dichotomised predictive model with optimal cut-offs for M-ficolin, platelets and haemoglobin, AUC was 99% and PPV 98% in detecting ALL from JIA.ConclusionM-ficolin is a valuable marker to differentiate the child with ALL from JIA.

Endothelial dysfunction has not previously been investigated as a thrombogenic risk factor among patients with acute lymphoblastic leukemia (ALL), known to be at high risk of thromboembolism. We retrospectively explored the association between three circulating biomarkers of endothelial dysfunction (thrombomodulin, syndecan-1, VEGFR-1) measured in prospectively collected blood samples and risk of thromboembolism in 55 cases and 165 time-matched controls, treated according to the NOPHO ALL2008 protocol. In age-, sex-, and risk group-adjusted analysis, increasing levels of thrombomodulin and VEGFR-1 were independently associated with increased odds of developing thromboembolism (OR 1.37 per 1 ng/mL [95% CI 1.20‒1.56, P 30 days before thromboembolic diagnosis. Thrombomodulin levels were on average 3.2 ng/mL (95% CI 2.6-8.2 ng/mL) higher in samples with measurable asparaginase activity (P

Key Points Overall asparaginase-associated toxicity and relapse were not significantly associated with increased asparaginase enzyme activity levels.The risk of pancreatitis and osteonecrosis were significantly associated with increasing asparaginase enzyme activity., Visual Abstract, Asparaginase treatment is a mainstay in contemporary treatment of acute lymphoblastic leukemia (ALL), but substantial asparaginase-related toxicity may lead to jeopardized protocol compliance and compromises survival. We investigated the association between risk of asparaginase-associated toxicities (AspTox) and asparaginase enzyme activity (AEA) levels in 1155 children aged 1.0 to 17.9 years, diagnosed with ALL between July 2008 and March 2016, and treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol. Patients with ≥2 blood samples for AEA measurement drawn 14 ± 2 days after asparaginase administration were included (6944 trough values). AEA was measurable (or >0 IU/L) in 955 patients, whereas 200 patients (17.3%) had asparaginase inactivation and few AspTox recorded. A time-dependent multiple Cox model of time to any first asparaginase-associated toxicity adjusted for sex and age was used. For patients with measurable AEA, we found a hazard ratio (HR) of 1.17 per 100 IU/L increase in median AEA (95% confidence interval [CI], 0.98-1.41; P = .09). For pancreatitis, thromboembolism, and osteonecrosis, the HRs were 1.40 (95% CI, 1.12-1.75; P = .002), 0.99 (95% CI, 0.70-1.40; P = .96), and 1.36 (95% CI, 1.04-1.77; P = .02) per 100 IU/L increase in median AEA, respectively. No significant decrease in the risk of leukemic relapse was found: HR 0.88 per 100 IU/L increase in AEA (95% CI, 0.66-1.16; P = .35). In conclusion, these results emphasize that overall AspTox and relapse are not associated with AEA levels, yet the risk of pancreatitis and osteonecrosis increases with increasing AEA levels.

Obesity is associated with poor outcomes in childhood acute lymphoblastic leukaemia (ALL). We explored whether severe treatment-related toxicity and treatment delays could explain this observation. This study included 1 443 children aged 2 center dot 0-17 center dot 9 years with ALL treated with the Nordic Society of Pediatric Haematology and Oncology (NOPHO) ALL2008 non-high-risk protocol. Prospective treatment-related toxicities registered every three-month interval were used. Patients were classified according to sex- and age-adjusted international childhood cut-off values, corresponding to adult body mass index: underweight, = 30 kg/m(2). Obese children had a higher incidence rate ratio (IRR) for severe toxic events {IRR: 1 center dot 55 [95% confidence interval (CI) 1 center dot 07-2 center dot 50]}, liver and kidney failures, bleeding, abdominal complication, suspected unexpected severe adverse reactions and hyperlipidaemia compared with healthy-weight children. Obese children aged >= 10 years had increased IRRs for asparaginase-related toxicities compared with healthy-weight older children: thromboses [IRR 2 center dot 87 (95% CI 1 center dot 00-8 center dot 21)] and anaphylactic reactions [IRR 7 center dot 95 (95% CI 2 center dot 15-29 center dot 37)] as well as higher risk for truncation of asparaginase [IRR 3 center dot 54 (95% CI 1 center dot 67-7 center dot 50)]. The high prevalence of toxicity and a higher risk of truncation of asparaginase may play a role in the poor prognosis of obese children aged >= 10 years with ALL.

IntroductionThromboembolism is a serious toxicity of acute lymphoblastic leukemia treatment, and contributes to substantial morbidity and mortality. Several single nucleotide polymorphisms have been associated with thromboembolism in the general population; however, their impact in patients with acute lymphoblastic leukemia, particularly in children, remains uncertain.Materials and methodsWe collected constitutional DNA and prospectively registered thromboembolic events in 1252 patients, 1–45 years, with acute lymphoblastic leukemia included in the Nordic Society of Pediatric Hematology and Oncology ALL2008 protocol in the Nordic and Baltic countries (7/2008–7/2016). Based on previously published data and a priori power calculations, we selected four single nucleotide polymorphisms: F5 rs6025, F11 rs2036914, FGG rs2066865, and ABO rs8176719.ResultsThe 2.5 year cumulative incidence of thromboembolism was 7.1% (95% confidence interval (CI) 5.6–8.5). F11 rs2036914 was associated with thromboembolism (hazard ratio (HR) 1.52, 95%CI 1.11–2.07) and there was a borderline significant association for FGG rs2066865 (HR 1.37, 95%CI 0.99–1.91), but no association for ABO rs8176719 or F5 rs6025 in multiple cox regression. A genetic risk score based on F11 rs2036914 and FGG rs2066865 was associated with thromboembolism (HR 1.45 per risk allele, 95%CI 1.15–1.81), the association was strongest in adolescents 10.0–17.9 years (HR 1.64).ConclusionIf validated, a F11 rs2036914/FGG rs2066865 risk prediction model should be tested as a stratification tool for prevention of thromboembolism in patients with acute lymphoblastic leukemia. Introduction: Thromboembolism is a serious toxicity of acute lymphoblastic leukemia treatment, and contributes to substantial morbidity and mortality. Several single nucleotide polymorphisms have been associated with thromboembolism in the general population; however, their impact in patients with acute lymphoblastic leukemia, particularly in children, remains uncertain. Materials and methods: We collected constitutional DNA and prospectively registered thromboembolic events in 1252 patients, 1–45 years, with acute lymphoblastic leukemia included in the Nordic Society of Pediatric Hematology and Oncology ALL2008 protocol in the Nordic and Baltic countries (7/2008–7/2016). Based on previously published data and a priori power calculations, we selected four single nucleotide polymorphisms: F5 rs6025, F11 rs2036914, FGG rs2066865, and ABO rs8176719. Results: The 2.5 year cumulative incidence of thromboembolism was 7.1% (95% confidence interval (CI) 5.6–8.5). F11 rs2036914 was associated with thromboembolism (hazard ratio (HR) 1.52, 95%CI 1.11–2.07) and there was a borderline significant association for FGG rs2066865 (HR 1.37, 95%CI 0.99–1.91), but no association for ABO rs8176719 or F5 rs6025 in multiple cox regression. A genetic risk score based on F11 rs2036914 and FGG rs2066865 was associated with thromboembolism (HR 1.45 per risk allele, 95%CI 1.15–1.81), the association was strongest in adolescents 10.0–17.9 years (HR 1.64). Conclusion: If validated, a F11 rs2036914/FGG rs2066865 risk prediction model should be tested as a stratification tool for prevention of thromboembolism in patients with acute lymphoblastic leukemia.

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.

Purpose: To investigate the risk of steroid-induced ocular hypertension in children treated with systemic glucocorticoid. Methods: Prospective cohort study of children treated with high-dose systemic glucocorticoid (prednisolone-equivalent >0.5 mg/kg/day) for more than 2 weeks. Intraocular pressure (IOP) was measured by an Icare tonometer. An intraocular hypertensive response was defined as a net increase in IOP ≥6 mmHg from baseline or a peak IOP ≥21 mmHg in either eye. Patients with a peak IOP ≥31 mmHg or a net increase in IOP ≥15 mmHg were considered as high responders. Results: Sixteen children with median age 12 years (range 5–17) were included in the study. Nine children (56%) developed a steroid-induced ocular hypertensive response. Two children (12%) were high responders with peak IOP between 32 and 44 mmHg and a net increase in IOP between 15 and 23 mmHg. All children were asymptomatic and IOP was normalized in all after withdrawal of steroid. Steroid responders were significantly younger than nonresponders (p = 0.03). No associations were found between net IOP increase and time to peak pressure, steroid dose at peak pressure or accumulated prednisolone dose at peak IOP. Conclusion: Systemic treatment of children with glucocorticoid can cause a significant increase in IOP which indicates the need for IOP screening of these children. The risk of steroid-induced ocular hypertension may depend on age and ethnicity. In this perspective, further studies on Caucasian children are needed.

ObjectivesSurvival among children diagnosed with acute lymphoblastic leukaemia (ALL) has increased considerably. However, morbidity in survivors constitutes a potential increasing burden not limited to secondary health care. Our objectives were to compare health care utilisation, including both primary and secondary health care, between childhood ALL survivors and matched references up to 15 years after curative treatment. Moreover, to increase knowledge on survivors’ health service seeking behaviour as time from treatment elapsed.Design and settingA Danish population-based matched cohort study linking multiple nationwide registries.Participants675 cases, diagnosed with childhood (1.0–17.9 years) ALL between 1994 and 2015, and 6750 matched references sampled randomly from the source population (matched on age, gender and geographical region).Primary outcome measuresRepeated consultations in general practice and hospital (outpatient and inpatient) estimated as yearly rates from 2.5 years after diagnosis and onwards. We compared cases and references with yearly incidence rate ratios (IRRs) from negative binomial regression models.ResultsSurvivors of childhood ALL had a mean number of yearly daytime contacts in general practice of 4.75 (95% CI 4.41 to 5.11) the first year, corresponding to an IRR of 1.85 (95% CI 1.71 to 2.00); decreasing to 1.16 (1.01 to 1.34) after 15 years, and without significant impact of gender (p=0.894) or age (p=0.399). For hospital contacts, ALL survivors had a mean number of yearly contacts of 14.21 (13.38–15.08) the first year, corresponding to an IRR of 31.50 (28.29–35.07); decreasing to 2.42 (1.59–3.68) after 15 years. No differences were found across calendar time.ConclusionsALL survivors used significantly more health care services across sectors than the reference population. Decreasing use over 15 years illustrated the dynamics of health care needs; this knowledge may inform the future organisation of integrated follow-up programmes.Trial registration numberNCT03985826.

aintenance therapy containing methotrexate and 6-mercapto-purine is essential to cure acute lymphoblastic leukemia (ALL). Cytotoxicity is elicited by incorporation of thioguanine nucleotides into DNA (DNA-TG), and higher leukocyte DNA-TG is associated with increased relapse-free survival. As 6-thioguanine provides 6-fold higher cytosolic levels of thioguanine nucleotides than does 6-mercaptopurine, we added low-dose 6-thioguanine to methotrexate/6mercaptopurine maintenance therapy to explore if this combination results in significantly higher DNA-TG. The target population of the “Thiopurine Enhanced ALL Maintenance therapy” (TEAM) study was 30 patients with non-high-risk ALL, aged 1-45 years on methotrexate/6-mercaptopurine maintenance therapy receiving no other systemic chemotherapy. Incremental doses of 6-thioguanine were added to methotrexate/6-mercaptopurine maintenance therapy (starting 6-thioguanine dose: 2.5 mg/m2/day, maximum: 12.5 mg/m2/day). The primary endpoint was DNA-TG increments. Thirty-four patients were included, and 30 patients completed maintenance therapy according to the TEAM strategy. Of these 30 patients, 26 (87%) tolerated 10.0-12.5 mg/m2/day as the maximum 6-thioguanine dose. TEAM resulted in significantly higher DNA-TG levels compared to those in both TEAM patients before their inclusion in TEAM (on average 251 fmol/mg DNA higher [95% confidence interval: 160-341; P

Acute lymphoblastic leukemia (ALL) is the most common cancer in children. Following intensification of therapy, survival rates approach 90%.1 However, more than 50% of children with ALL develop acu...

Infants with acute lymphoblastic leukaemia (ALL) have a high frequency of central nervous system (CNS) involvement. Flow cytometric analysis of cerebrospinal fluid (CSF) was recently demonstrated to be a sensitive method for detecting CNS involvement in childhood ALL. In the present study, CSF from 14 infants was collected at routine lumbar punctures and analysed by multicolour flow cytometry. At initial diagnosis, leukaemic blasts were detected in CSF by flow cytometry in 11 patients (78·6%) compared to seven patients (50%) by cytospin. Larger studies are needed to determine if CSF flow cytometry has prognostic value in infant ALL.

ObjectivesTo investigate health care utilisation including both primary and secondary health care 6 months before the diagnosis of a relapse or a second malignant neoplasm (SMN) in survivors of childhood acute lymphoblastic leukaemia (ALL).Design and settingA Danish population-based matched cohort study linking multiple nationwide registries.ParticipantsParticipants were recruited from a total of 622 childhood ALL 2.5-year event-free survivors diagnosed between 1994 and 2015. Cases were survivors developing a relapse or an SMN and references were survivors still in first remission. Each case was matched with five references on age, sex, treatment protocol and risk group.Primary outcome measuresConsultations in general practice and hospital the last 6 months before relapse or SMN. Cases and references were compared with monthly incidence rate ratios (IRRs) from negative binomial regression models.ResultsOf the 622 childhood ALL survivors, 60 (9.6%) developed a relapse (49) or an SMN (11) and 295 matched references were identified. Health care utilisation in general practice increased among cases the last month before the event compared with references with an IRR of 2.71 (95% CI 1.71 to 4.28). Data showed a bimodal structure with a significantly increased number of visits 4, 5 and 6 months before the event. Hospital health care utilisation increased 2 months before the event in cases with an IRR of 5.01 (3.78 to 6.63) the last month before the event and an IRR of 1.94 (1.32 to 2.85) the second-last month comparing cases and references.ConclusionsSurvivors of childhood ALL developing a relapse or an SMN have a short period of increased health care utilisation before diagnosis. At hospital, this might be explained by pre-diagnostic examinations. In general practice, data suggest a bimodal structure with children later developing a relapse having more contacts also half a year before the relapse, suggesting that there could be early warnings.

Objectives: This is a protocol for a Cochrane Review (intervention). The objectives are as follows:. To assess the effect of the number of PEG-asparaginase doses on survival and relapse in children and adolescents with acute lymphoblastic leukaemia (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 (NMA) 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).

Acute lymphoblastic leukemia (ALL) is a rare disease in infants. Asparaginase is an essential part of the treatment, and there Acute is a need to evaluate the efficiency and safety of this drug in this age group. We evaluated the pharmacokinetics of intramuscularly administered native E. coli asparaginase (Asparaginase Medac®) and PEG-asparaginase (Oncaspar®) as well as hypersensitivity reactions during treatment in Interfant-06 ( www.clinicaltrials.gov : NCT01025804). All patients without hypersensitivity had sufficiently high enzyme activity levels during treatment with both preparations. Patients with hypersensitivity reactions during treatment, characterized by the presence of either or not of clinical symptoms and no measurable enzyme activity, received ineffective therapy. For optimization of the bad prognosis in infant ALL, therapeutic drug monitoring should be performed for identification of patients who should be switched to a different asparaginase preparation because of inactivation of the drug.

IntroductionMore than 90% of patients diagnosed with childhood acute lymphoblastic leukaemia (ALL) today will survive. However, half of the survivors are expected to experience therapy-related chronic or late occurring adverse effects, reducing quality of life. Insight into underlying risk trajectories is warranted. The aim of this study is to establish a Nordic, national childhood ALL survivor cohort, to be investigated for the total somatic and psychosocial treatment-related burden as well as associated risk factors, allowing subsequent linkage to nation-wide public health registers.Methods and analysisThis population-based observational cohort study includes clinical follow-up of a retrospective childhood ALL survivor cohort (n=475), treated according to a common Nordic ALL protocol during 2008–2018 in Denmark. The study includes matched controls. Primary endpoints are the cumulative incidence and cumulative burden of 197 health conditions, assessed through self-report and proxy-report questionnaires, medical chart validation, and clinical examinations. Secondary endpoints include organ-specific outcome, including cardiovascular and pulmonary function, physical performance, neuropathy, metabolic disturbances, hepatic and pancreatic function, bone health, oral and dental health, kidney function, puberty and fertility, fatigue, and psychosocial outcome. Therapy exposure, acute toxicities, and host genome variants are explored as risk factors.Ethics and disseminationThe study is approved by the Regional Ethics Committee for the Capital Region in Denmark (H-18035090/H-20006359) and by the Danish Data Protection Agency (VD-2018–519). Results will be published in peer-reviewed journals and are expected to guide interventions that will ameliorate the burden of therapy without compromising the chance of cure.

Publisher Copyright: © 2021 Lippincott Williams and Wilkins. All rights reserved. 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 aged 1.0 to 17.9 y) 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.

Truncation of asparaginase treatment due to asparaginase-related toxicities or silent inactivation (SI) is common and may increase relapse risk in acute lymphoblastic leukemia (ALL). We investigated relapse risk following suboptimal asparaginase exposure among 1401 children aged 1 to 17 years, diagnosed with ALL between July 2008 and February 2016, treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol (including extended asparaginase exposure [1000 IU/m2 intramuscularly weeks 5-33]). Patients were included with delayed entry at their last administered asparaginase treatment, or detection of SI, and followed until relapse, death, secondary malignancy, or end of follow-up (median, 5.71 years; interquartile range, 4.02-7.64). In a multiple Cox model comparing patients with (n = 358) and without (n = 1043) truncated asparaginase treatment due to clinical toxicity, the adjusted relapse-specific hazard ratio (HR; aHR) was 1.33 (95% confidence interval [CI], 0.86-2.06; P = .20). In a substudy including only patients with information on enzyme activity (n = 1115), the 7-year cumulative incidence of relapse for the 301 patients with truncation of asparaginase treatment or SI (157 hypersensitivity, 53 pancreatitis, 14 thrombosis, 31 other, 46 SI) was 11.1% (95% CI, 6.9-15.4) vs 6.7% (95% CI, 4.7-8.6) for the 814 remaining patients. The relapse-specific aHR was 1.69 (95% CI, 1.05-2.74, P=.03). The unadjusted bone marrow relapse-specific HR was 1.83 (95% CI, 1.07-3.14, P=.03) and 1.86 (95% CI, 0.90- 3.87, P=.095) for any central nervous system relapse. These results emphasize the importance of therapeutic drug monitoring and appropriate adjustment of asparaginase therapy when feasible. This trial was registered at www.clinicaltrials.gov as #NCT03987542.

Central nervous system (CNS) involvement by cytospin is associated with increased risk of relapse in childhood acute lymphoblastic leukemia. We investigated if flow cytometric analysis of cerebrospinal fluid (CSF) at diagnosis improves the prediction of relapse. This prospective cohort study included patients (1.0–17.9 years) treated according to the Nordic Society of Pediatric Hematology and Oncology ALL2008 protocol. CSF flow cytometry samples were obtained at 17 centers, preserved with Transfix®, and analyzed at a central laboratory. One-hundred and seventy-one (25.4%) of 673 patients were positive by flow cytometry (CNSflow+). The 4-year cumulative incidence of relapse was higher for patients with cytospin positivity (CNScyto+) (17.1% vs. 7.5%), CNSflow+ (16.5% vs. 5.6%), and cytospin and/or flow positivity (CNScomb+) (16.7% vs. 5.1%). In Cox regression analysis stratified by immunophenotype and minimal residual disease day 29 and adjusted by sex, predictors of relapse were age (hazard ratio [HR] 1.1, 95% CI 1.1–1.2, P < 0.001), white blood cell count at diagnosis (HR 1.4, 95% CI 1.1–1.6, P < 0.001), and CNScomb+ (HR 2.2, 95% CI 1.0–4.7, P = 0.042). Flow cytometric analysis of CSF improves detection of CNS leukemia, distinguishes patients with high and low risk of relapse, and may improve future risk stratification and CNS-directed therapy.

PURPOSE Asparaginase is a key component of acute lymphoblastic leukemia (ALL) therapy. Hypersensitivity reactions challenge its use and occur frequently (30-75%) after native Escherichia. Coli (E.coli) asparaginase (Appel et al., 2008; Muller et al., 2001; Panosyan et al., 2004; Silverman et al., 2001). The international ALL Ponte di Legno Toxicity Work Group (PTWG) classifies hypersensitivity to asparaginase as (i) allergy in case of symptoms of allergy (always associated with undetectable asparaginase activity levels), (ii) allergic-like reactions in case of symptoms without inactivation, and (iii) silent inactivation (SI) with inactivation of asparaginase activity, but without hypersensitivity symptoms (Schmiegelow et al., 2016). Allergic-like reactions and SI can only be diagnosed with monitoring of asparaginase activity levels. A meta-analysis was performed based on data from the PTWG to estimate the incidence of hypersensitivity and risk factors for hypersensitivity to asparaginase in ALL protocols using pegylated E.coli asparaginase (PEGasparaginase) as first line of treatment. PATIENTS AND METHODS Questionnaires were sent to all members of the PTWG. Information on protocol level regarding PEGasparaginase dose, dosing regimen (e.g. dosing frequency, total number of doses, PEGasparaginase-free intervals(s)), administration route, total induction and post-induction hypersensitivity rates per protocol and per risk group and use of therapeutic drug monitoring (TDM). To facilitate comparison between protocols with and without TDM, we defined allergic reactions as the sum of allergies and allergic-like reactions. Silent inactivation was analyzed separately. RESULTS A total of 5880 patients with newly diagnosed ALL, aged 1 to 24 years old, were enrolled in seven different upfront ALL protocols using PEGasparaginase as first-line treatment. The overall incidence of allergic reactions along with 95% confidence interval (CI) were 9% [6%; 13%], 2% [1%; 3%] and 8% [5%; 11%] in the overall protocol, induction and post-induction, respectively (Figure 1). Severity of allergic reactions were described, according to the CTCAE version 3.0 or 4.03, per protocol. 47% of the reactions were classified as grade 3/4. Univariate meta-regression analysis showed a positive association between the incidence of allergic reactions and number of PEGasparaginase-free intervals (P=0.005). High risk group stratification (P Two out of seven study groups reported an incidence of allergic reactions of 1.6-2.0%, which was 9-16% of all hypersensitivity. Three out of seven study groups reported an incidence of SI of 3.7-4.1%, which was 23-29% of all hypersensitivity reactions. All protocols prescribed a switch to Erwinia asparaginase in case of clinical hypersensitivity and/or SI. 308 out of 348 (89%) of the patients with hypersensitivity to PEGasparaginase received Erwinia asparaginase. 19 out of these 308 (6%) exposed patients had an allergic reaction to Erwinia asparaginase, of which 7 out of 19 (37%) were grade 3/4. CONCLUSION The incidence of allergic reactions is lower in protocols using PEGasparaginase as first-line treatment compared to that reported for native E.coli asparaginase or PEGasparaginase after native E.coli asparaginase. Post-induction phase, a higher number of PEGasparaginase-free intervals, and initiation of PEGasparaginase in post-induction phase are risk factors for allergic reactions. These results are important for planning of PEGasparaginase administrations in future frontline therapy. Figure 1 Figure 1. Disclosures Albertsen: Erytech: Honoraria, Speakers Bureau; Servier: Speakers Bureau; BKA: Other: Sponsor of the investigator-initiated trial NOR-GRASPALL2016.

Introduction: Asparaginase is an essential part of the treatment of acute lymphoblastic leukemia (ALL). Hypersensitivity occurred in 16.8% (clinical allergy (13.8%) or silent inactivation (3.0%)) of patients treated with pegylated asparaginase (PEG-asp) in the NOPHO ALL2008 cohort (Hoejfeldt et al 2018). Hypersensitivity (clinical allergy or silent inactivation) is the most common cause of truncated asparaginase therapy, and truncated treatment has been associated with decreased event-free survival (Silverman et al 2001). Asparaginase encapsulated in erythrocytes (eryaspase) is an alternative formulation of asparaginase aiming to prolong the half-life of asparaginase and to reduce toxicity e.g. hypersensitivity, since the erythrocyte membrane prevents activation of the immune system and protects asparaginase against elimination. A phase 2 study has demonstrated prolonged asparaginase enzyme activity (AEA) and significantly reduced incidence of hypersensitivity in patients with ALL, who had a prior exposure to other asparaginase preparations (NCT01518517). The aim of the NOR-GRASPALL 2016 study is to evaluate the safety and efficacy of eryaspase in combination with multiagent chemotherapy according to the NOPHO ALL2008 protocol and the ALLTogether Pilot study. Antileukemic treatment in these protocols include 4-8 doses of PEG-asp as first line treatment. Methods: NOR-GRASPALL 2016 is a phase 2 multinational multicentre trial conducted in the Nordic/Baltic countries. It is a single-arm study for non-high-risk patients with ALL and hypersensitivity to PEG-asp. Eryaspase (150 U/kg) is scheduled to complete the intended course of asparaginase (1-7 doses). AEA-measurements are used as biomarkers for treatment efficacy. Results: Since August 2017, 36 children and two adults were included in the study. Median age was 6.0 years (IQR: 3.3;8.7). 37 patients (97.4%) had clinical allergy to PEG-asp of whom 59.5% (n=22) had a severe allergic reaction. One patient (3.3%) was included due to silent inactivation. AEA-measurements were available in all patients but one (n=37), and in none of these patients AEA was detectable following PEG-asp treatment. In total, 171 doses of eryaspase were administered. A total of 34 of the 36 patients (94.7%) had AEA >100 U/L and 27 patients (71.1%) had AEA-levels >400 U/L 14 days after first eryaspase administration (expected nadir). The median AEA-level was 798 U/L [IQR: 387;864]. In total 90.7% of all samples collected 14 days after eryaspase administration had AEA >100 U/L and 69.3% had AEA >400 U/L. The median AEA-level was 621U/L [IQR: 331;962]. Adverse events with relation to eryaspase were reported in 8 of 36 patients (22%). Six patients experienced a possible allergic reaction to eryaspase; one patient had a severe allergic reaction, three patients developed a rash and two patients had "drug fever", deemed related to eryaspase. Three of these six patients (50%) had low AEA-levels after developing allergic symptoms, the remaining patients (50%) had AEA-levels comparable with all other patients in the study. Four patients experienced adverse events related to eryaspase; two patients with mild hyperlipidaemia and two with hepatoxicity. No other severe adverse events with relation to eryaspase have been reported. Final study results will be provided at the meeting. Conclusion: Eryaspase consistently demonstrated prolonged AEA in patients who developed hypersensitivity reactions to PEG-asp. Treatment with eryaspase was well tolerated. We conclude that eryaspase is a promising alternative to PEG-asp in case of hypersensitivity. Disclosures Schmiegelow: Jazz Pharmaceuticals: Other: Speaker and/or Advisory Board Honoraria ; Amgen: Other: Speaker fee; Medscape: Other: Speaker fee; Servier: Other: Educational grant. Speaker and/or Advisory Board Honoraria . Albertsen:Erytech Pharma: Other: Sponsor of the investigator initiated study: NOR-GRASPALL 2016. No financial benefits..

PURPOSE Asparaginase is an essential drug in childhood acute lymphoblastic leukemia (ALL) therapy and is frequently given for months to obtain continuous asparagine depletion. We randomly assigned patients to continuous versus intermittent pegylated-asparaginase (PEG-asp) treatment, hypothesizing there would be decreased toxicity with unchanged efficacy. METHODS Children (median age, 4.2 years) treated for non–high-risk ALL according to the Nordic Society for Pediatric Hematology and Oncology ALL2008 protocol received five intramuscular PEG-asp injections (1,000 IU/m2) every two weeks and were then randomly assigned to additional three doses (6-week intervals [experimental arm], n = 309) versus 10 doses (2-week intervals [standard arm], n = 316). The primary end point was noninferior (6% margin) disease-free survival. Toxicity reduction was a secondary end point. Occurrence of asparaginase-associated hypersensitivity, pancreatitis, osteonecrosis, and thromboembolism were prospectively registered. RESULTS After a median follow-up of 4.1 years, the 5-year disease-free survival was 92.2% (95% CI, 88.6 to 95.8) and 90.8% (95% CI, 87.0 to 94.6) in the experimental and standard arms, respectively. The 3-year cumulative incidence of any first asparaginase-associated toxicity (hypersensitivity [n = 13]; osteonecrosis [n = 29]; pancreatitis [n = 24]; thromboembolism [n = 17]) was 9.3% in the experimental arm and 18.1% in the standard arm ( P = .001). Asparaginase-associated toxicity reduction was confirmed in sex- and risk-group–adjusted Cox regression analysis stratified by age (≥ 10 and < 10 years; hazard ratio, 0.48; P = .001). The experimental arm had the lowest incidences of all four toxicities, reaching significance for pancreatitis (6-month risk, 5.8% v 1.3%; P = .002). CONCLUSION The excellent cure rates and reduced toxicity risk support the use of intermittent PEG-asp therapy after the first 10 weeks in future childhood ALL trials that apply prolonged PEG-asp therapy.

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.

Premature discontinuation of asparaginase reduces cure rate in contemporary acute lymphoblastic leukemia (ALL) treatment. One of the commonest causes of asparaginase truncation is asparaginase-associated pancreatitis (AAP). We prospectively registered AAP during treatment of 2,448 consecutive Nordic/Baltic ALL patients aged 1.0-45.9 years treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol (7/2008-10/2018). The Day 280 cumulative incidence of first-time AAP (including 99% (167/168) of AAP events at this time point) was 8.3% (95% confidence interval (CI) 7.0-9.9) with a median time of 104 days (interquartile range (IQR) 70-145) from ALL diagnosis to AAP, with a median of 10 days (IQR 6-13) from last asparaginase exposure, and after a median number of five asparaginase doses (IQR 3-7, max 14 doses). All patients received polyethylene glycol conjugated Escherichia coli-derived asparaginase as standard treatment. Eighty-five percent (140/164, unknown in N=4) of AAP events were severe (AAP-associated symptoms and/or pancreatic enzymes >3x upper normal limit lasting >72 hours or with hemorrhagic pancreatitis, pancreatic abscess, or pseudocyst). Four age groups were defined: 1.0-4.9, 5.0-8.9, 9.0-16.9, and 17.0-45.9 years-each containing approximately 25% of the AAP events. Compared with patients aged 1.0-4.9 years, adjusted (sex, immunophenotype, and white blood cell count) hazard ratios (HR) of AAP were associated with higher age (5.0-8.9 years: HR 2.3, 95% CI 1.5-3.6, P Of 168 AAP patients, 34 (20%) were re-challenged with asparaginase. Fifty percent (17/34) developed a second episode of AAP-41% being severe (7/17). The median time to a second AAP event from asparaginase re-exposure was 29 days (IQR 16-94) and occurred after a median of two asparaginase doses (range 0-7). Neither age group nor severity of the first AAP was associated with increased hazard of a second AAP event. None of the patients with a second AAP were further re-exposed to asparaginase, and none died of the second AAP. Among a total of 196 ALL relapses, 21 patients have had AAP including 17 patients with asparaginase truncation. However, the hazard of relapse (age- and sex-adjusted) was not increased among AAP patients with asparaginase truncation versus AAP patients with asparaginase re-exposure (5.0-year cumulative incidence of relapse: 13.2% versus 14.2%) (HR 1.0, 95% CI 0.3-3.1, P=1.0). When analyzing time to relapse among AAP patients versus non-AAP patients, no difference in hazard of relapse was found (HR 2.0, 95% CI 0.8-4.9, P=.2). In conclusion, adolescents and young adults tolerated asparaginase treatment as well as children; however, the risk of AAP was higher for patients older than 5.0 years of age with no difference with increasing age. Despite a low AAP-related mortality, the morbidity was considerable and most profound for patients aged 9.0-16.9 years. Since asparaginase re-exposure was associated with a high risk of a second AAP event and neither AAP development nor AAP-related asparaginase truncation was associated with increased relapse risk, asparaginase re-exposure should be attempted only in patients with a high risk of leukemic relapse. Finally, there is an unmet need for preventive strategies toward AAP. Disclosures Wolthers: Novo Nordisk: Employment.

Introduction: Asparaginase is a key component in the treatment of childhood acute lymphoblastic leukemia (ALL), but the treatment is jeopardized by 20% or more developing asparaginase-associated toxicities (asp-tox), mostly hypersensitivity, osteonecrosis, pancreatitis and thromboembolism (Albertsen et al 2019). Therapeutic drug monitoring (TDM) of asparaginase enzyme activity (AEA) levels is widely used to identify patients with no AEA and to ensure sufficient treatment (Sluis et al 2016), but is not commonly used to identify patients with high levels. In this study, we investigate AEA-levels and the association with risk and severity of asp-tox. Methods: Children aged 1-17.9 years with non high-risk ALL treated according to the NOPHO ALL2008 protocol from July 2008 to March 2016 in the Nordic and Baltic countries were included in the study. Based on median AEA-level measured 14 days (+/-2 days) after administration, patients were grouped into four groups; 'no enzyme activity' (0 IU/L, n=201), 'fast clearance' (1-99 IU/L, n=82), 'therapeutic levels' (100-249 IU/L, n=543), and 'high levels' (≥250 IU/L, n=330). Furthermore, groups with AEA-levels Results: We included 1,156 patients and 6,929 samples for AEA-measurements in the study. The median number of samples for each patient was 5 [IQR: 3;9]. A total of 328 asp-tox events were registered in 311 patients (27.5%). The median age for patients with asp-tox was 5 years [Interquartile range (IQR): 2;9] compared with 4 years [IQR: 2;6] for patients without asp-tox (p Conclusion: We found no difference in the incidence of toxicities between AEA in ´therapeutic levels´ and ´high levels´ group, and there will be no clinical advantage in using TDM to identify patients with high AEA-levels for dose adjustment. The significantly lower incidence of asp-tox in patients without AEA and AEA-levels Disclosures Ranta: Roche: Other: Amember of Steering committee for a Roche study on Hemlibra (the contract is between Karolinska University Hospital and Roche). No financial benefits.. Wolthers:Novo Nordisk: Current Employment. Heyman:Servier: Other: Research funding in ALLTogether (research protocol). Schmiegelow:Jazz Pharmaceuticals: Other: Speaker and/or Advisory Board Honoraria ; Medscape: Other: Speaker fee; Servier: Other: Educational grant. Speaker and/or Advisory Board Honoraria ; Amgen: Other: Speaker fee. Albertsen:Erytech Pharma: Other: Sponsor of the investigator initiated study: NOR-GRASPALL 2016. No financial benefits..

When offered participation in clinical trials, families of children with cancer face a delicate balance between cure and toxicity. Since parents and children may perceive this balance differently, this paper explores whether adolescent patients have different enrollment patterns compared to younger children in trials with different toxicity profiles.

Thromboembolism frequently occurs during acute lymphoblastic leukemia (ALL) therapy. We prospectively registered thromboembolic events during the treatment of 1772 consecutive Nordic/Baltic patients with ALL aged 1 to 45 years who were treated according to the Nordic Society of Pediatric Hematology and Oncology ALL2008 protocol (July 2008-April 2017). The 2.5-year cumulative incidence of thromboembolism (N = 137) was 7.9% (95% confidence interval [CI], 6.6-9.1); it was higher in patients aged at least 10 years (P < .0001). Adjusted hazard ratios (HRas) were associated with greater age (range, 10.0-17.9 years: HRa, 4.9 [95% CI, 3.1-7.8; P < .0001]; 18.0-45.9 years: HRa, 6.06 [95% CI, 3.65-10.1; P < .0001]) and mediastinal mass at ALL diagnosis (HRa, 2.1; 95% CI, 1.0-4.3; P = .04). In a multiple absolute risk regression model addressing 3 thromboembolism risk factors, age at least 10 years had the largest absolute risk ratio (RRage, 4.7 [95% CI, 3.1-7.1]; RRenlarged lymph nodes, 2.0 [95% CI, 1.2-3.1]; RRmediastinal mass, 1.6 [95% CI, 1.0-2.6]). Patients aged 18.0 to 45.9 years had an increased hazard of pulmonary embolism (HRa, 11.6; 95% CI, 4.02-33.7; P < .0001), and patients aged 10.0 to 17.9 years had an increased hazard of cerebral sinus venous thrombosis (HRa, 3.3; 95% CI, 1.5-7.3; P = .003) compared with children younger than 10.0 years. Asparaginase was truncated in 38/128 patients with thromboembolism, whereas thromboembolism diagnosis was unassociated with increased hazard of relapse (P = .6). Five deaths were attributable to thromboembolism, and patients younger than 18.0 years with thromboembolism had increased hazard of dying compared with same-aged patients without thromboembolism (both P ≤ .01). In conclusion, patients aged at least 10 years could be candidates for preemptive antithrombotic prophylaxis. However, the predictive value of age 10 years or older, enlarged lymph nodes, and mediastinal mass remain to be validated in another cohort.

Background Asparaginase is an essential drug for childhood acute lymphoblastic leukemia (ALL) and is frequently given for months to obtain continuous asparagine depletion. This causes significant toxicity. We randomized patients to continuous versus intermittent asparaginase, hypothesizing decreased toxicity with unchanged efficacy (www.clinicaltrials.gov: NCT00819351). Methods Children (median age: 4·2 years) treated for non-high risk ALL according to the NOPHO ALL2008 protocol received five intramuscular pegylated asparaginase injections (1·000 IU/m2) biweekly and were then randomized to additional three (6 weeks intervals, N=309, experimental arm) versus ten (two weeks intervals, N=316, standard arm) doses. Primary endpoint was non-inferior (6% margin) disease free survival (DFS). Toxicity reduction was secondary endpoint. Occurrence of asparaginase-associated hypersensitivity, osteonecrosis, pancreatitis and thromboembolism were prospectively registered at quarterly intervals. Findings After a median follow-up of 4·1 years, the 7-year DFS was 90·4% (95% confidence interval, 85·4-95·4) and 90·8% (95% confidence interval, 87·0-94·6) in the experimental and standard arms, respectively. The 3-year cumulative incidence of any first toxicity (hypersensitivity (N=13), osteonecrosis (N=29), pancreatitis (N=24), thromboembolism (N=17)) was 9·3% in the experimental arm and 18·1% in the standard arm (P=0·001). Toxicity reduction was confirmed in sex- and risk group-adjusted Cox regression analysis stratified by age (≥10 and

Objectives This randomized controlled trial tested the hypothesis that children with non-high risk acute lymphoblastic leukemia could benefit from individualized 6-mercaptopurine increments during consolidation therapy (NCT00816049). Primary and secondary end points were end of consolidation minimal residual disease (MRD) positivity and event-free survival. Methods 392 patients were randomized to experimental and 396 to standard therapy. Patients allocated to standard therapy received oral 6-mercaptopurine (25 mg/m2/day) from days 30 to 85, while the experimental arm received stepwise increments of additional 25 mg/m2/day beginning on days 50 and/or 71 unless dose-limiting myelosuppression had occurred. Results In the experimental arm, 166 patients (42%) received one dose increment, and 62 (16%) received two. 57 of 387 (15%) in the experimental arm were MRD positive at end of consolidation versus 77 of 389 (20%) in the control arm (P=0.08). Five-year probability of event-free survival was 0.89 (95% CI: 0.85–0.93) in the experimental arm versus 0.93 (0.90–0.96) in the control arm (P=0.13). The median accumulated length of 6-mercaptopurine treatment interruptions was 7 (IQR 2–12) in the experimental arm versus 4 (IQR 0–10) in the control arm (P=0.002). Conclusion This study found no benefit from individualized 6-mercaptopurine increments compared to standard therapy. This article is protected by copyright. All rights reserved.

The survival rate of childhood acute lymphoblastic leukemia (ALL) is now close to 90 %. However, 15-20 % of patients still experience relapse, which is caused by persistence of minimal residual disease (MRD) in the bone marrow during chemotherapy. Thus, a method for identification of drugs that are capable of eliminating this cell population is necessary, but not currently available. Indeed, current and past ALL in vitro sensitivity assays demand high cell numbers (100,000 ALL cells per well in a 96-well plate), which is beyond what can routinely be harvested from the MRD population in the BM at the end of induction therapy. Accordingly, we developed a cell death assay that is far more sensitive and needs only 1,000 cells per well in a 96-well plate. It is based on stainings with annexinV-V450, a marker for early apoptosis, and Live/Dead Yellow, a marker for loss of cell membrane integrity, which can be quantified by flow cytometry. In order to compare patient samples, the viable fraction of treated cells were normalized to the viable fraction of untreated cells and classified as the survival index (SI). Assay time was set to 24 hours. When developing the assay we included the drugs that are currently used in the NOPHO ALL2008 induction therapy, namely vincristine, doxorubicin, dexamethasone and prednisolone. We determined one empirically derived cut-off concentration per drug and per cell density that produced a large scatter of SIs. Thereby only one drug concentration per cell density was needed for in vitro sensitivity testing (Vincristine: 0.09 and 9.23 mg/ml; doxorubicin: 0.5 and 2 mg/ml; prednisolone: 50 and 200 mg/ml; dexamethasone 2 and 100 mg/ml). The cell death assay showed only minor day-to-day variation (e.g. 0.09 mg/ml vincristine: N=15; rS= 0.92, p < 0.001) (Figure 1). In order to simulate a situation where FACS would be used for isolation of ALL subpopulations or MRD prior to in vitro sensitivity testing, ALL cells were mixed with peripheral blood mononuclear cells (MNCs) from healthy individuals to a final leukemic cell concentration of 10-2 and thereafter Fluorescence-activated cell sorted (FACSed) directly into a 96-well plate for exposure to chemotherapeutic drugs. The SI obtained was highly correlated to that of ALL cells that were not sorted, but directly and manually pipetted into the 96-well plate (e.g. 0.09 mg/ml vincristine: N=9; rS= 0.90, p = 0.001) (Figure 2). Next, we tested whether the in vitro sensitivity results obtained using 1,000 cells per well would resemble results obtained using 100,000 cells per well (i.e. the current standard). We exposed 1,000 and 100,000 cells per well in a 96-well plate from 36 ALL patients and three healthy individuals to the drugs listed above. For all drugs the SI for 1,000 and 100,000 cells per well were significantly correlated (vincristine: rs=0.65, p < 0.001; doxorubicin: rs= 0.48, p = 0.003; dexamethasone: rs= 0.55, p < 0.001; prednisolone: rs=0.35, p=0.04). Thus, we have developed a sensitive, yet robust in vitro sensitivity testing platform that includes FACS prior to cell death analysis. It demands only 3,000 ALL cells per drug to be tested in triplicates, and 3,000 cells that serve as untreated controls. Since a standard follow-up BM sample at day 28 after diagnosis contains at least 20 million MNCs in total, it enables in vitro sensitivity profiling of patients with MRD value > 0.1 %, potentially allowing future tailored chemotherapy according to the chemosensitivity profile of residual leukemia. Disclosures No relevant conflicts of interest to declare.

Background L-Asparaginase is an effective drug in the treatment of childhood acute lymphoblastic leukemia (ALL). The use of L-asparaginase may be limited by serious adverse events of which allergy is the most frequent. The objective of this study was to describe the clinical aspects of PEG-asparaginase allergy in children treated according to the Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol. Procedure Children (1–17 years) enrolled in the NOPHO ALL2008 protocol between July 2008 and August 2011, who developed PEG-asparaginase allergy were identified through the NOPHO ALL2008 toxicity registry. In the NOPHO ALL2008 protocol, patients are randomized to 8 or 15 doses of intramuscular PEG-asparaginase (Oncaspar®) 1,000 IU/m2/dose administered at 2 or 6 weeks intervals during a total period of 30 weeks. (Clinical trials.gov no: NCT00819351). Results Of 615 evaluable patients, 79 patients developed clinical PEG-asparaginase allergy (cumulative risk; 13.2%) and discontinued PEG-asparaginase therapy for that reason. PEG-asparaginase allergy occurred after a median of two doses (75% range 2–4, max 14). In 58% of PEG-asparaginase hypersensitive patients, the clinical allergic reactions appeared within 2 hr after PEG-asparaginase administration and ranged from mild symptoms to systemic anaphylaxis. Nine patients experienced an anaphylactic reaction within 1 hr and 50 min from asparaginase administration; none were fatal. Four of 68 patients (6%) who subsequently received Erwinase therapy also reacted allergic to Erwinase. Conclusion Clinical allergy to PEG-asparaginase occurred early in treatment, was in general moderate in severity, and mostly developed within 2 hr after PEG-asparaginase administration. The risk of subsequent Erwinase allergic reactions was low. Pediatr Blood Cancer 2015;62:427–433. © 2014 Wiley Periodicals, Inc.

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 CONCLUSIONS: PEG-asparaginase increases cytotoxic 6MP metabolite levels and risk of SOS, potentially interacting with other chemotherapy pulses.

Steroid-induced osteonecrosis (ON) is a serious complication of anti-leukemic therapy in children and young adults with acute lymphoblastic leukemia (ALL). Patients with ON experience severe pain and reduced mobility, ultimately leading to surgery with arthroplasty. Survival of ALL has increased to

BACKGROUND: As pegylated asparaginase is becoming the preferred first-line asparaginase preparation in the chemotherapy regimens of childhood acute lymphoblastic leukemia (ALL), there is a need to evaluate this treatment.METHODS: The aim of this study was to evaluate the pharmacokinetics of prolonged upfront biweekly PEG-asparaginase (where PEG is polyethylene glycol) treatment by measuring serum l-asparaginase activity and formation of anti-PEG-asparaginase antibodies. A total of 97 evaluable patients (1-17 years), diagnosed with ALL, and treated according to the NOPHO ALL2008 protocol (where NOPHO is Nordic Society of Paediatric Haematology and Oncology) were included. In the NOPHO ALL2008 protocol, patients are randomized to 8 or 15 doses of intramuscular PEG-asparaginase (Oncaspar(®) ) 1,000 IU/m²/dose, at 2-week or 6-week intervals with a total of 30-week treatment (Clinical trials.gov. no.: NCT00819351).RESULTS: The pharmacological target of treatment (l-asparaginase activity above 100 IU/l) was reached in 612 of 652 (94%) samples obtained 14 ± 2 days after PEG-asparaginase administration. Mean l-asparaginase activity was 338 IU/l. Six patients had l-asparaginase activity below 50 IU/l in all samples. A total of 25 patients (26%) developed Immunoglobulin G (IgG) anti-PEG-asparaginase antibodies, but there was no correlation between anti-PEG-asparaginase antibodies and low levels of asparaginase activity.CONCLUSION: We conclude that prolonged first-line biweekly PEG-asparaginase therapy, 1,000 IU/m²/dose was above the pharmacological target in the vast majority of patients. Presence of anti-PEG-asparaginase antibodies was not a predictor of l-asparaginase activity.

Background: Central nervous system (CNS) involvement is common in childhood acute lymphoblastic leukemia (ALL). Today all patients receive intensive prophylactic CNS-directed therapy, which is associated with short- and long-term neurotoxicity. The conventional method for diagnosing CNS leukemia is by microscopic examination of cytospin preparations of cerebrospinal fluid (CSF). Both high (CNS3: ≥5 x 109 cells/L) and low level CNS disease (CNS2: Methods: Cytospin results were collected from local oncology clinics for patients treated according to the Nordic Society of Pediatric Hematology (NOPHO) ALL2008 protocol from July 2008 to December 2017 (N=1841). CSF samples for FCM were obtained from patients enrolled from September 2012 to December 2017 at 17 participating centers (N=669). CSF samples were collected into Transfix® tubes (Intermedico Ltd., Hellerup, Denmark) and shipped to Rigshospitalet, Copenhagen, Denmark for centralized analysis as previously described (Levinsen at al., Pediatr Blood Cancer 2016). FCM positivity required detection of ≥10 cells with a leukemia-associated phenotype. CSF FCM results were blinded to the treating physician. Time to relapse was analyzed using Cox proportional hazards models with delayed entry at remission and with death and second malignant neoplasm as competing events. Results: At diagnosis, 241 of 1841 (13.1%; CNS2: 8.9% and CNS3: 4.2%) patients were positive by cytospin, whereas 167 of 669 (25.0%) patients were positive by FCM. FCM positivity was not associated with shipment duration (median: 2 days). In total, 191 of the 669 patients (28.6%) were CNS positive by cytospin and/or FCM. CNS positivity was associated with higher white blood cell (WBC) count at diagnosis, T-cell ALL, lack of t(12;21), and traumatic lumbar puncture (TLP) (all comparisons: p < 0.001). However, patients with CNS positivity did not differ in their end of induction bone-marrow minimal residual disease (MRD) levels compared to the remaining patients (cytospin: median MRD 1.2 x 10-4 vs. 0.9 x 10-4, p = 0.058; FCM: median MRD 2.0 x 10-4 vs. 1.7 x 10-4, p = 0.62). During follow-up, 30 patients relapsed with nine of the relapses involving the CNS and 16 relapses isolated to the bone-marrow. The 4-year cumulative incidence of any relapse was higher for patients who were CNS positive by cytospin (16.1% vs. 8.9%), FCM (18.6% vs. 6.0%), and combined cytospin/FCM (19.0% vs. 5.5%) (Figure 1a). Simple Cox regressions yielded relapse hazard ratio (HR) estimates of CNS positivity at diagnosis of 2.4 for cytospin (95% CI 1.0-5.7, p = 0.04), 3.5 for FCM (95% CI 1.7-7.2, p < 0.001), and 4.1 for combined cytospin/FCM (95% CI 2.0-8.7, p < 0.001). Cytospin and/or FCM was associated with increased risk of both isolated bone-marrow relapse (16 events, HR 3.1, 95% CI 1.2-8.4, p = 0.024) and of any CNS relapse (9 events, HR 4.9, 95% CI 1.2-19.5, p = 0.025). In a multiple Cox model stratified by immunophenotype and risk group, predictors of relapse were age (per year: HR 1.1, 95% CI 1.0-1.2, p = 0.003), WBC at diagnosis (per doubling: HR 1.3, 95% CI 1.1-1.6, p = 0.005), and cytospin and/or FCM (HR 3.2, 95% CI 1.4-7.2, p = 0.006) (Figure 1b). Cytospin and/or FCM was associated with a significantly higher risk of relapse for BCP-ALL (N=581; 23 relapses; HR 4.5, 95% CI 1.9-10.4, p = < 0.001). For T-cell ALL no significant association was observed (N=85; 7 relapses; HR 1.6, 95% CI 0.3-8.2, p = 0.58), however the number of T-cell ALL was too small to allow reliable conclusions. In a simple Cox model, TLP was associated with a significantly higher risk of relapse than no TLP (HR 2.7, 95% CI 1.3-5.9, p = 0.011), but this was only the case for patients who were positive by FCM (FCM pos: HR 2.7, 95% CI 1.0-7.0, p = 0.043; FCM neg: 0.7, 95% CI 0.1-5.0, p = 0.68). Conclusion: FCM markedly increases the detection rate for CNS involvement at diagnosis, and distinguish between patients at high and low risk of relapse. Diagnosis of CNS leukemia by combined cytospin and FCM analysis should be the standard for accurate classification of CNS status, which will enable better stratification of CNS-directed and systemic therapy. Disclosures No relevant conflicts of interest to declare.

Asparaginase (ASP)-associated pancreatitis (AAP) occurs during acute lymphoblastic leukemia treatment. Among 1285 children (1.0-17.9 years) diagnosed during July 2008-December 2014 and treated according to the Nordic/Baltic ALL2008 protocol, 86 (cumulative incidence=6.8%) developed AAP. Seventy-three cases were severe (diagnostic AAP criteria persisting >72 h) and 13 mild. Cases were older than controls (median: 6.5 vs 4.5 years; P=0.001). Pseudocysts developed in 28%. Of the 20 re-exposed to ASP, 9 (45%) developed a second AAP. After a median follow-up of 2.3 years, 8% needed permanent insulin therapy, and 7% had recurrent abdominal pain. Germline DNA on 62 cases and 638 controls was genotyped on Omni2.5exome-8-v1.2 BeadChip arrays. Overall, the ULK2 variant rs281366 showed the strongest association with AAP (P=5.8 × 10(-7); odds ratio (OR)=6.7). Cases with the rs281366 variant were younger (4.3 vs 8 years; P=0.015) and had lower risk of AAP-related complications (15% vs 43%; P=0.13) compared with cases without this variant. Among 45 cases and 517 controls

ESSENTIALS: Children with acute lymphoblastic leukemia (ALL) are at risk of thromboembolism (TE). This is a prospective evaluation of the incidence, risk factors and outcomes of TE in 1038 children with ALL. TE occurred in 6.1% of children, with the highest incidence (20.5%) among those aged 15-17 years. A TE-associated case fatality of 6.4% indicates that TE is a severe complication of ALL treatment.Thromboembolism (TE) is a major toxicity in children with acute lymphoblastic leukemia (ALL) and may have a negative impact on ALL treatment.To examine the cumulative incidence, outcomes and risk factors associated with TE in children with leukemia.We prospectively evaluated TE in 1038 Nordic children and adolescents (≥ 1 and18 years) diagnosed with ALL during 2008-2013 and treated according to the NOPHO (Nordic Society of Pediatric Hematology and Oncology)-ALL 2008 protocol. The cohort was followed until December 2014. Cox proportional regression was used to compute hazard ratios (HRs).TE events (n = 63) occurred most frequently in conjunction with asparaginase (ASP) administration (52/63). The cumulative incidence of TE was 6.1% (95% confidence interval [CI], 4.8-7.7). Being aged 15-17 years was associated with an increased risk of TE (adjusted HR of 4.0; 95% CI, 2.1-7.7). We found a TE-associated 30-day case fatality of 6.4% (95% CI, 1.8-15.5) and TE-related truncation of ASP therapy in 36.2% (21/58). Major hemorrhage occurred in 3.5% (2/58) of anticoagulated patients. Minor hemorrhage was reported in two out of 58 patients. No major bleeds occurred in children who received low-molecular-weight heparin.Methods to identify children and adolescents who will benefit from thromboprophylaxis during ALL treatment are called for. The truncation of ASP should be avoided. The long-term survival outcomes for ALL patients with TE require close monitoring in the future.

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.

Background To evaluate if dissolution of asparaginase in lidocaine can relieve pain of an intramuscular injection in children without changes in bioavailability. Procedure The study was designed as a double-blinded study, randomizing 12 children with acute lymphoblastic leukemia (ALL) to four different combinations of injections, including two injections where asparaginase was dissolved in a lidocaine solution and two in sterile water. Seventeen treatment courses of asparaginase, each consisting of four injections, were evaluated. Pain intensity (Pain Visual Analog Scale, VAS-score) and pharmacokinetics of the drug was evaluated. Results The pain scores showed a significant difference between the two solutions of asparaginase (±lidocaine) (P value

Background Determination of the frequency of antibody formation during first and second exposure to Erwinia asparaginase after i.v. and i.m. administration. Procedure Thirty-nine children with newly diagnosed acute lymphoblastic leukemia (ALL) were included in this prospective study. Antibodies were determined (ELISA method) in plasma from these patients on specific days during and after therapy with 30,000 IU/m2 i.v. or i.m. every day for ten days during the induction phase (first exposure). For 19 children, antibodies were measured in plasma during and after the re-induction phase (second exposure) following treatment with 30,000 IU/m2 i.v. or i.m. twice a week for two weeks (Mondays and Thursdays). On the same days of therapy, enzyme activity (spectrophotometric method) and the concentration of asparagine (HPLC) was determined. Results During the first exposure, none of the patients developed anti-Erwinia asparaginase antibodies. During the second exposure, one patient (1 of 8 patients) treated intravenously developed antibodies, which were associated with disappearance of enzyme activity and reappearance of asparagine. Three of eleven patients developed antibodies of pharmacokinetic importance after i.m. therapy. None of the children had any clinical symptoms of hypersensitivity. Conclusions The formation of antibodies and subsequently altered pharmacokinetics of Erwinia asparaginase seemed to be of importance only during a second period of asparaginase therapy. Med. Pediatr. Oncol. 2002;38:310–316. © 2002 Wiley-Liss, Inc.

Aims Evaluation of l-asparaginase therapy in the NOPHO-92 ALL-protocol (treatment protocol of acute lymphoblastic leukaemia of the Nordic Society of Paediatric Haematology and Oncology, initiated in 1992) after intravenous and intramuscular administration of Erwinia asparaginase during induction and re-induction therapy. Methods Forty children with newly diagnosed acute lymphoblastic leukaemia received Erwinia asparaginase (30 000 IU/m2 i.v. or i.m.) during induction therapy (every day for 10 days), and 19 children received Erwinia asparaginase (30 000 IU/m2 i.v. or i.m.) during re-induction therapy (twice a week for 2 weeks). Within the treatment periods asparaginase trough activity (using a spectrophotometric assay) was determined on specific days. The goal of therapy is complete l-asparagine depletion, which asparaginase activities above 100 IU l−1 have been shown to ensure. Therefore determination of l-asparagine (using a h.p.l.c. method) was performed only in plasma samples with asparaginase activities below 100 IU l−1. Results During induction therapy 92.2% of the trough enzyme activities were above 500 IU l−1 for the i.v.-treated patients, and 92.4% of the trough enzyme activities were above 500 IU l−1 for the i.m.-treated patients. During re-induction therapy 64.7% of the trough enzyme activities were below 100 IU l−1 in the i.v.-treated group, and 73.3% of the trough enzyme activities were below 100 IU l−1 in the i.m.-treated group. For trough enzyme activities below 100 IU l−1l-asparagine depletion was complete in two thirds of the samples. Conclusions In the NOPHO-92 ALL-protocol l-asparaginase treatment during induction therapy was unnecessarily intense, but during the re-induction phase it appeared inadequate.

SummaryL-asparaginase is an important drug in the treatment of childhood acutelymphoblastic leukaemia (ALL). Treatment is associated with several toxici-ties, including acute pancreatitis. Clinical course, presentation, re-exposureto L-asparginase after pancreatitis and risk of recurrent pancreatitis withinan asparaginase-intensive protocol has been poorly reported. Children (1–17 years) on the ongoing Nordic Society of Paediatric Haematology andOncology (NOPHO) ALL2008 protocol with asparaginase-associated pan-creatitis (AAP) diagnosed between 2008 and 2012 were identified throughthe online NOPHO ALL toxicity registry. NOPHO ALL2008 includes eightor 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 expo-sure to PEG-asparaginase (clinicaltrials.gov no: NCT00819351). Of 786children, 45 were diagnosed with AAP with a cumulative risk of AAP of5 9%. AAP occurred after a median of five doses (range 1–13), and 11 d(median) from the latest administration of PEG-Asparaginase. Thirteenpatients developed pseudocysts (30%) and 11 patients developed necrosis(25%). One patient died from pancreatitis. Twelve AAP patients werere-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.Keywords: L-asparaginase, leukaemia, pancreatitis, toxicity, risk factors.

Asparaginase is essential in the treatment of lymphoproliferative malignancies, but it is associated with several side effects. The objective of this study was to compare asparaginase-induced alterations of the coagulation inhibitors and the impact on central line-associated thrombosis in children treated according to 2 different asparaginase regimens. The study enrolled 30 children treated for acute lymphoblastic leukemia, and they were divided into 2 groups with respect to asparaginase preparation and protocol (NOPHO ALL-1992 versus NOPHO ALL-2000). The coagulation inhibitors antithrombin, protein C, and proteins S were measured prior to and during asparaginase therapy, and incidence of central line-associated thromboses was compared to evaluate the protocols' thrombogenicity. Thirteen children received Erwinia asparaginase and 17 children received E. coli asparaginase. Independent of protocol, the coagulation inhibitors were significantly reduced during asparaginase therapy (p < .001), and central line-associated thromboses were frequent. Four children developed thrombosis in the course of asparaginase therapy, and there was a correlation between asparaginase-induced fall of antithrombin and occurrence of new thromboses (p = .01).

Introduction Children with acute lymphoblastic leukemia (ALL) are at high risk for VTE due to several thrombotic risk factors such as the disease itself, central venous line (CVL), immobilization, infections and treatment with asparaginase and steroids, leading to increased morbidity and mortality. Identifying the clinical risk factors and high risk treatment phases for VTE is important and can lead to a better outcome and quality of life for these children. We conducted this prospective study on symptomatic VTE in children with ALL to characterize the prevalence, the clinical characteristics, and potential clinical predictive factors for symptomatic VTE and the impact of thrombosis on treatment delays. Methods All patients (n=1083), age 1-18 years, diagnosed with B-cell precursor or T-cell ALL between June 2008 and July 2013 and enrolled in the NOPHO ALL 2008 treatment protocol in the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden), Estonia or Lithuania were included in the study. Thrombotic events (TE) were prospectively recorded until the end of December 2013. TE was defined as objectively confirmed symptomatic TE. Main questions were: time of VTE occurrence, impact on treatment delay, type of CVL, dysfunction of the CVL, blood samples including D-dimers and thrombophilia screening, family history of TE, type and duration of antithrombotic therapy, and major bleeding during anticoagulation. Results The cumulative risk of symptomatic VTE was 6.0% (CI 95% 4.7-7.7) for children treated with the NOPHO- ALL 2008 protocol. No arterial TE was found. VTE occurred in median 80 (IQR 43-118) days in the SR and 104 (IQR 39-127) days in the IR protocol and were in majority of cases associated with asparaginase treatment (84.5%, 49/58). See figure 1 for the localization of the VTE. VTE had a high impact on the treatment in the patients. Treatment with asparaginase was shortened in half of patients with VTE and chemotherapy treatment delayed in 25%. Age ≥ 15 years and residual disease ≥ 5% after induction therapy was significantly associated with VTE in the multivariate analysis (Table 1). Conclusions Our findings indicate that Venous Thromboembolism (VTE): - is a major complication of ALL treatment - may lead to reduced intensity of the ALL treatment and subsequently possible long term impact on the EFS - risk is dependent on the patients age and residual disease after leukemia induction The possibility of identifying patients with elevated risk of VTE needs to be studied further and thromboprophylaxis for such patients during high-risk treatment phases can be considered in future ALL protocols. Table 1. Multivariate Cox regression analysis of the risk for VTE Factor HR (95% CI) P value Age category, years 1-7 8-14 15-17 Ref1.9 (1.0-3.7)6.2 (3.4-11.3) Figure 1. Localization of VTE Figure 1. Localization of VTE Disclosures No relevant conflicts of interest to declare.

Background: Central nervous system (CNS)-directed treatment has reduced risk of CNS relapse for childhood acute lymphoblastic leukemia (ALL), which accounts for 30-40% of initial relapses. Compared with CNS-negative patients, patients with CNS leukemia (>5 leukocytes/µL cerebrospinal fluid (CSF) and lymphoblasts) suffer from more CNS+ relapses. Conventional cytology (CC) is specific (>95%), but nonsensitive ( Method: We prospectively assessed centralised multi-parameter flow cytometry (FCM) of fixated CSF versus local CC in Nordic/Baltic childhood ALL. Diagnostic samples from 172 children aged 0-18 years with de novo and eight children with relapsed ALL were investigated in 297 CSF samples from 180 patients. Kinetics of disappearance of leukemic cells in the CSF was evaluated until day 15. Antibody-combinations reflected the immunophenotype of leukemic blasts in bone marrow. Result: Of 172 newly diagnosed patients, 51 (30%) had CSF involvement by FCM, while CC was positive in 16 patients (9%) (p Conclusion: Leukemic blasts are present in spinal fluid of one third of newly diagnosed ALL. CSF involvement is associated with other higher risk characteristics. The prognostic value of these findings awaits prospective evaluation. Disclosures No relevant conflicts of interest to declare.

PURPOSE: A case-control study was performed to determine whether patients who had been treated with Erwinia asparaginase as part of their treatment for childhood acute lymphoblastic leukemia (ALL) and who showed relapsed of their disease more often developed anti-asparaginase antibodies than patients who remained in remission.METHODS: A group of 13 patients who showed relapsed of their disease (median follow-up 35 months) were randomly matched with control patients of the same risk group (two control patients to each case), who had received therapy of the same intensity during the same period (median follow-up 70 months). Anti- Erwinia asparaginase antibodies were measured (ELISA method) during maintenance therapy after asparaginase treatment (30,000 IU/m(2) daily for 10 days in all patients plus twice weekly for 2 weeks in intermediate-risk and high-risk ALL patients).RESULTS: The overall incidence of anti- Erwinia asparaginase antibodies was 8% (3 of 39 patients). There was no statistically significant difference in the incidence of antibody formation between patients who had suffered relapse (1 of 13) and those who had not (2 of 26). In two of the three patients who developed antibodies, the antibodies disappeared after some time, whereas one patient had measurable antibody levels for more than a year after asparaginase therapy.CONCLUSIONS: In this study, the development of anti-Erwinia asparaginase antibodies was rare and was unrelated to the risk of relapse.

PURPOSE: To describe the pharmacokinetics of Erwinia asparaginase (ASNase) after intravenous (i.v.) and intramuscular (i.m.) administration.METHODS: A group of 29 children with newly diagnosed acute lymphoblastic leukemia (ALL) received Erwinia ASNase 30,000 IU/m2 every day for 10 days during multiagent induction therapy. Of these patients. 13 received i.v. therapy and 16 received i.m. therapy. During the reinduction phase the patients received Erwinia ASNase 30,000 IU/m2 twice a week for 2 weeks (Mondays and Thursdays) (8 patients in the i.v.-treated group and 11 patients in the i.m.-treated group). ASNase activity (spectrophotometric assay) was measured in plasma samples obtained from the patients at various times during therapy.RESULTS: The estimated half-life was 6.4 +/- 0.5 h (n = 13), the absorption rate after i.m. administration was found to limit elimination. The apparent volume of distribution corresponded well with the volume of plasma. The estimated clearance suggested that Erwinia ASNase is a low-clearance drug. Bioavailability after i.m. administration was (mean +/- SEM) 27.0 +/- 4.5% (range 11-61%; n = 12).CONCLUSIONS: In this study the pharmacokinetic parameters after i.v. and i.m. administration of Erwinia ASNase were determined based on a substantial number of patients. The present findings emphasize the importance of conducting proper pharmacokinetic studies before a new drug or a new preparation of a drug is introduced in a different schedule.