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 ( < .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; < .0001]; 18.0-45.9 years: HRa, 6.06 [95% CI, 3.65-10.1; < .0001]) and mediastinal mass at ALL diagnosis (HRa, 2.1; 95% CI, 1.0-4.3; = .04). In a multiple absolute risk regression model addressing 3 thromboembolism risk factors, age at least 10 years had the largest absolute risk ratio (RR, 4.7 [95% CI, 3.1-7.1]; RR, 2.0 [95% CI, 1.2-3.1]; RR, 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; < .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; = .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 ( = .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 ≤ .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.

SummaryWe 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.

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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 acute lymphoblastic leukaemia (ALL). Treatment is associated with several toxicities, including acute pancreatitis. Clinical course, presentation, re-exposure to L-asparginase after pancreatitis and risk of recurrent pancreatitis within an asparaginase-intensive protocol has been poorly reported. Children (1-17 years) on the ongoing Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol with asparaginase-associated pancreatitis (AAP) diagnosed between 2008 and 2012 were identified through the online NOPHO ALL toxicity registry. NOPHO ALL2008 includes eight or 15 doses of intramuscular pegylated L-asparginase (PEG-asparaginase) 1000 iu/m 2 /dose at 2-6 weeks intervals, with a total of 30 weeks of exposure to PEG-asparaginase (clinicaltrials.gov no: NCT00819351). Of 786 children, 45 were diagnosed with AAP with a cumulative risk of AAP of 5Á9%. AAP occurred after a median of five doses (range 1-13), and 11 d (median) from the latest administration of PEG-Asparaginase. Thirteen patients developed pseudocysts (30%) and 11 patients developed necrosis (25%). One patient died from pancreatitis. Twelve AAP patients were re-exposed to L-asparginase, two of whom developed mild AAP once more, after four and six doses respectively. In conclusion, re-exposure to PEGasparaginase in ALL patients with mild AAP seems safe.

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; 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 <10 years, the strongest associations with AAP were found for RGS6 variant rs17179470 (P=9.8 × 10; OR=7.3). Rs281366 is located in the ULK2 gene involved in autophagy, and RGS6 regulates G-protein signaling regulating cell dynamics. More than 50% of AAP cases <10 years carried one or both risk alleles.

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.

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.