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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.

Patients undergoing treatment for acute lymphoblastic leukaemia (ALL) are at risk of coagulopathy, especially thromboembolism. We conducted a survey on practices in the assessment and management of coagulopathy during the new ALLTogether protocol in 29 (17 paediatric, 12 adult) Nordic and Baltic cancer centres. While 92% of adult centres used thromboprophylaxis with low-molecular-weight heparin, no paediatric centre did. Almost all providers performed baseline coagulation studies, but only 59% continued the assessment. Fibrinogen replacement was conducted in 59%, and antithrombin replacement in 28% of the centres. The survey highlights the need for guidelines in the management of coagulopathy during ALL therapy. publishedVersion

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.

Acute lymphoblastic leukaemia (ALL) has a high survival rate, but treatment is lengthy with risk of severe side-effects, which may also impact parents' health-related quality of life (HRQOL). We present data on 526 parents of 310 children treated for ALL according to the NOPHO ALL2008-protocol, in Sweden, Finland and Denmark. Parents were asked to complete the 36-Item Short Form Survey (SF-36) at least 6 months after end of treatment and data were compared with Norwegian reference data. Parental background factors were collected via a study-specific questionnaire. Participating parents scored significantly lower than the reference population on both physical and mental summary indexes, but only surpassed a minimal clinically important difference for the mental summary index (Mental Component Summary [MCS]). Mothers scored lower than fathers in the MCS and stopped working and took care of the affected child more often than the fathers. Higher mental HRQOL was associated with male gender and living in Finland or Denmark (compared to Sweden). Correlations within spouses in physical and mental scores were weak to moderate. In conclusion, ALL negatively affects parental HRQOL, especially the mental domains, even after treatment. Findings suggest that mothers are more affected than fathers and may require extra support.

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.

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

Relapse remains the main obstacle to curing childhood acute lymphoblastic leukemia (ALL). The aims of this study were to compare incidence of relapse, prognostic factors, and survival after relapse between three consecutive Nordic Society of Pediatric Hematology and Oncology trials. Relapse occurred as a primary event in 638 of 4 458 children (1.0–14.9 years) diagnosed with Ph-negative ALL between 1992 and 2018. The 5-year cumulative incidence of relapse was 17.3% (95% CI 15.4–19.2%) and 16.5% (95% CI 14.3–18.8%) for patients in the ALL1992 and ALL2000 trials, respectively, but decreased to 8.4% (95% CI 7.0–10.1%) for patients in the ALL2008 trial. No changes in duration of first complete remission and site of relapse were observed over time; however, high hyperdiploidy, and t(12;21) decreased in the ALL2008 trial. The 4-year overall survival after relapse was 56.6% (95% CI 52.5–60.5%) and no statistically significant temporal improvements were observed. Age ≥10 years, T-cell immunophenotype, bone-marrow involvement, early and very early relapse, hypodiploidy, and Down syndrome all independently predicted worse outcome after relapse. Improvements in the primary treatment of childhood ALL has resulted in fewer relapses. However, failure to improve outcome of remaining relapses suggests a selection of harder-to-cure relapses and calls for new therapeutic strategies.

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.

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 0.0001] and OR 1.21 per 100 pg/mL [95% CI 1.02‒1.21, P = 0.005], respectively). These associations remained significant when including only samples drawn30 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 0.0001). Among single nucleotide variants located in or neighboring coding genes for the three biomarkers, none were significantly associated with odds of thromboembolism. If results are validated in another cohort, thrombomodulin and VEGFR-1 could serve as predictive biomarkers, identifying patients in need of preemptive antithrombotic prophylaxis.

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.

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.

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 (CNS

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.

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.

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.

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.

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.

Immunophenotype-defined sub-populations are common at diagnosis in childhood B-cell precursor acute lymphoblastic leukemia

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.

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.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/m(2) /dose administered at 2 or 6 weeks intervals during a total period of 30 weeks. (Clinical trials.gov no: NCT00819351).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.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.

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).

To evaluate if dissolution of asparaginase in lidocaine can relieve pain of an intramuscular injection in children without changes in bioavailability.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.The pain scores showed a significant difference between the two solutions of asparaginase (+/-lidocaine) (P value0.0001). Lidocaine did not influence the pharmacokinetics of the drug.Asparaginase with addition of lidocaine significantly decreases the pain as measured by the visual analog scale without changing the bioavailability or the absorption rate of the enzyme.

Determination of the frequency of antibody formation during first and second exposure to Erwinia asparaginase after i.v. and i.m. administration.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/m(2) 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/m(2) 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.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.The formation of antibodies and subsequently altered pharmacokinetics of Erwinia asparaginase seemed to be of importance only during a second period of asparaginase therapy.

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.

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(-1) L-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.

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.