THROMBOTECT - a randomized study comparing low molecular weight heparin, antithrombin and unfractionated heparin for thromboprophylaxis during induction therapy of acute lymphoblastic leukemia in children and adolescents

Venous thromboembolism in adolescents and young adults with acute lymphoblastic leukemia treated on a pediatric-inspired regimen

Asparaginase (ASP)-containing regimens for acute lymphoblastic leukemia (ALL) are associated with venous thromboembolism (VTE). We evaluated the prevalence, risk factors, role of prophylaxis and clinical impact of VTE among adolescents and young adult (AYA) patients (15-50 years) treated on Dana-Farber Cancer Institute (DFCI) ALL protocols. The 1- and 2-year cumulative incidence of VTE were 31.9% (95% CI: 27.0%, 36.9%) and 33.5% (95% CI: 28.5%, 38.5%) respectively, with most events occurring during ASP-based consolidation phase (68.6%). VTE was more frequent in patients with overweight/obese vs. normal BMI (39.2% vs. 29.0%, p = 0.048). In a 1-year landmark analysis, the 4-year overall survival was 91.5%, without difference between patients with vs. without VTE (93.8% vs. 90.0%, p = 0.93). Relapse and non-relapse mortality rates were also similar. Among patients treated at Dana-Farber/Harvard Cancer Center, cerebral sinus vein thrombosis occurred in 3.6% of patients (8.5% of VTE events) in comparison to pulmonary embolism (32.9%) and deep vein thromboses (58.6%, 24.4% line-associated). In a Cox regression model for VTE free-time, elevated BMI was associated with shorter VTE free-time (HR 1.94 [95% CI 1.13-3.35], p = 0.018), while low molecular weight heparin (LMWH) prophylaxis as time-varying covariate was not. In conclusion, we found that VTE was frequent in AYAs treated on DFCI ALL protocols but did not impact survival outcomes. Overweight/obese BMI increased risk for VTE.

Associations Between Clinical Factors and Postoperative Thrombosis in Pediatric Cardiac Surgery Patients: A Single-Center Retrospective Study

IMPORTANCE

Postoperative thrombosis is a significant complication in pediatric cardiac surgery patients, contributing to morbidity and mortality. Identifying clinical factors associated with thrombosis can improve patient outcomes by guiding early detection and intervention.

OBJECTIVES

This study aimed to assess factors associated with postoperative thrombosis or thromboembolism in pediatric patients under 12 months old who underwent surgery for congenital heart disease (CHD). Design, Setting, and Participants: This retrospective cohort study analyzed electronic medical records from pediatric patients admitted to the Pediatric Cardiovascular Intensive Care Unit (PCICU) at the German Paediatric Heart Center, Bonn, between March 1, 2020, and March 1, 2021. A total of 197 children under 12 months old who underwent cardiac surgery were included in the analysis.

MAIN OUTCOMES AND MEASURES

Thrombosis was diagnosed postoperatively using imaging modalities such as ultrasound, echocardiography, and computed tomography. The primary outcome was the incidence of thrombosis and its association with clinical factors such as age, central venous catheter (CVC) duration, CRP levels, and D-dimer levels.

RESULTS

Among 197 patients, the incidence of thrombosis was 8.63%, predominantly venous (70.6%). Initial associations were observed between thrombosis and younger age, lower body weight, higher hematocrit, cyanosis, longer central venous catheter (CVC) use, and elevated C-reactive protein (CRP) and d-dimer levels. Receiver operating characteristic analysis indicated a higher risk in patients with d-dimer levels above 5.47 mg/L. The stepwise multiregression analysis identified longer CVC duration in situ (β = 0.553; p < 0.001), higher CRP levels (β = 0.217; p = 0.022), and younger age at admission (β = -0.254; p = 0.006) as significant predictors of thrombosis. Decision tree analysis identified CVC use longer than 12.5 days and CRP levels above 118.01 mg/L as the most critical risk factors.

CONCLUSIONS AND RELEVANCE

Postoperative thrombosis is a notable risk in pediatric CHD patients, particularly in neonates. Prolonged CVC use and elevated CRP levels are critical risk factors. Routine monitoring of D-dimer and CRP levels, along with timely sonographic screening, can aid early thrombosis detection and intervention. Further research is warranted to optimize thrombosis prevention strategies in this population.

Thromboprophylaxis with intermediate dose enoxaparin during asparaginase containing induction for young adults with acute lymphoblastic leukemia

Thrombosis rates among young adults receiving asparaginase (ASP) for acute lymphoblastic leukemia (ALL) can reach 34%, with highest risk during induction. Our institution implemented a standard practice of 1 mg/kg/day enoxaparin administered to young adults with ALL who are treated with ASP during induction. We performed a retrospective analysis of patients who received thromboprophylaxis with enoxaparin 1 mg/kg/day during ASP-containing induction for ALL at Oregon Health & Science University from 2012 to 2023. The primary outcome was the cumulative incidence of thrombosis during induction. Bleeding events were assessed. Sixty-two patients were included in our analysis. Four patients (6.5%; 95% CI 1.8%-15.7%) experienced a thrombotic event. Three events were catheter-associated and 1 event was a distal lower extremity deep vein thrombosis related to myositis. No cerebral sinus thromboses, thrombosis-related deaths or major bleeding events occurred. Intermediate-dose enoxaparin is a promising thromboprophylaxis strategy and warrants further prospective research.

Thrombotic Complications in Pediatric Cancer

Thromboembolism (TE) complicates the course of pediatric cancer in a considerable number of cases. Cancer-related TE is attributed to an interaction of the underlying malignancy, the effects of therapy, and a possible thrombophilia predisposition. More specifically, recognized risk factors include a very young age and adolescence, non-O blood group, type and site of cancer, inherited thrombophilia, presence of central venous catheter, and type of chemotherapy. TE in children with cancer most commonly occurs in their extremities. In the absence of evidence-based guidelines for the management of thrombotic complications in pediatric oncology patients, TE management follows general recommendations for the management of pediatric TEs. Given the limitations of conventional anticoagulant therapy, direct oral anticoagulants could provide an alternative; however, their safety and efficacy in children with cancer remain to be seen. As for thromboprophylaxis, numerous studies have been conducted, albeit with conflicting results. Although the survival of pediatric oncology patients has significantly improved in recent years, morbidity due to cancer-related TE remains, underlying the need for large multicenter trials investigating both TE management with currently available agents and primary prevention.

Recurrent Cerebral Venous Sinus Thrombosis Occurred in an Acute Lymphoblastic Leukemia Child with Mutated Lipoprotein Lipase Gene during Asparaginase Therapy

Cerebral venous sinus thrombosis (CVST) and hyperlipidemia are severe complications of L-Asparaginase (L-Asp) during the treatment of B-cell acute lymphoblastic leukemia (B-ALL). Herein, we reported a 9-year-old B-ALL boy who underwent abnormal hypertriglyceridemia and CVST presenting as seizures and disturbance of consciousness twice during the induction therapy. Fortunately, he survived treatment with anticoagulant and lipid-lowering therapy. No thrombophilia-related gene mutation was detected, but a heterozygous mutation in lipoprotein lipase (LPL) gene was identified. His neurological symptoms were managed with short-term anticoagulant therapy and long-term lipid-lowering therapy. This case illustrated the manifestation and potential pathogenesis of CVST and highlighted the essentiality of screening baseline lipid profile and dyslipidemia- and thrombophilia-related gene mutation.

Global coagulation assays detect an early prothrombotic state in children with acute lymphoblastic leukemia

BACKGROUND

Pediatric patients with acute lymphoblastic leukemia (ALL) are at highest risk of venous thromboembolism during the induction therapy (IT). These events are not predictable by conventional coagulation assays.

OBJECTIVES

To investigate the utility of global coagulation assays (GCAs) for assessing the hemostatic state in children with ALL during IT.

METHODS

We included children with ALL (n = 15) and healthy controls (n = 15). Analyses were performed at different time points during IT of the AIEOP-BFM protocols. In addition to prothrombotic biomarkers, natural anticoagulant proteins, and in vivo thrombin generation (TG) markers, ex vivo TG was measured using the gold standard calibrated automated thrombogram method, automated ST Genesia, and thrombodynamics analyzer (TD). The latter also provided measurement of fibrin clot formation.

RESULTS

Different from conventional coagulation assays and in vivo TG markers, ex vivo GCAs detected increasing prothrombotic changes during IT. Particularly, TG measured with TD as expressed by endogenous thrombin potential was already significantly elevated at days 8 to 12 (P < .01) and continued to increase during IT compared with prior to beginning treatment, indicating a very early shift toward a procoagulant state. A similar pattern was observed for the rate of fibrin clot formation (stationary rate of clot growth: P < .01 at days 8-12). Remarkably, in patients developing thrombotic complications (n = 5), both GCAs, ST Genesia and TD, showed a significantly higher endogenous thrombin potential very early (already at days 8-12, P < .05), well before clinical manifestation.

CONCLUSION

GCAs capture prothrombotic changes early during IT in ALL pediatric patients. If confirmed, this approach will allow tailoring thromboprophylaxis in children with ALL at highest risk for venous thromboembolism.

Venous Thromboembolism Prophylaxis in Patients Treated for Acute Lymphoblastic Leukemia: A Comprehensive Systematic Review and Meta-Analysis

Acute lymphoblastic leukemia (ALL) is a common malignancy in children, often treated with intensive chemotherapy regimens. Venous thromboembolism (VTE) poses a significant risk during ALL treatment, leading to suboptimal outcomes. Thromboprophylaxis is crucial in mitigating this risk, but its efficacy and safety remain uncertain. This systematic review and meta-analysis aimed to evaluate the effectiveness of thromboprophylaxis in reducing VTE incidence during ALL treatment, focusing on antithrombin, apixaban, and enoxaparin. A systematic literature search adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed. Randomized controlled trials (RCTs) investigating thromboprophylaxis in ALL were included. Data extraction and quality appraisal were performed independently by three authors. Meta-analysis was conducted using Review Manager software. Three RCTs met the inclusion criteria. Apixaban, enoxaparin, and antithrombin were assessed in these trials. Meta-analysis revealed significantly reduced odds of VTE with thromboprophylaxis compared to standard care (odds ratio (OR): 0.47, 95% confidence interval (CI) 0.29-0.75; relative risk (RR): 0.52, 95% CI 0.33-0.83). However, no significant difference in bleeding risk was observed (OR: 1.33, 95% CI 0.42-4.21; RR: 1.32, 95% CI 0.43-4.07). Heterogeneity among studies was moderate. This study showed that thromboprophylaxis with apixaban, enoxaparin, or antithrombin significantly reduces VTE incidence during ALL treatment. Despite some limitations, including heterogeneity and potential biases, these findings support the adoption of tailored thromboprophylaxis strategies to improve outcomes in ALL patients. Further research is warranted to optimize these approaches and address remaining uncertainties.

A Randomized, Controlled Trial of Continuous Heparin Infusion to Prevent Asymptomatic Catheter-related Thrombosis at Discharge in Infants After Cardiac Surgery: The CHIP-CRT Trial

OBJECTIVES

There are conflicting results in preventing catheter-related thrombosis (CRT). Continuing infusion of unfractionated heparin (UFH) was a potential option for CRT. This study was to determine the effect of continuous UFH infusion on asymptomatic CRT at discharge in infants after cardiac surgery.

STUDY DESIGN

This study was a randomized, placebo-controlled, clinical trial at a single center. All infants with central venous catheters after cardiac surgery, below 3 months of age, were eligible. Stratified by CRT, infants were randomly assigned to the UFH group or the normal saline group. UFH was initiated at a speed of 10 to 15 units/kg/h for infants with CRT and 2 to 3 units/kg/h without CRT. The primary outcome was to determine the rate of CRT at discharge. The secondary outcomes included thrombosis 6 months after surgery, adverse events of UFH, and post-thrombotic symptoms.

RESULTS

Due to slow recruitment during the COVID-19 pandemic, this trial was prematurely stopped. Only 35 infants were randomly assigned to the UFH or control groups. There was no statistically significant difference in CRT rate at discharge ( P =0.429) and 6 months after surgery ( P =1.000) between groups. All CRTs except one disappeared at discharge. No thrombosis or post-thrombotic symptom was reported at follow-up evaluation. There was no difference between groups in duration of thrombus ( P =0.088), D dimer ( P =0.412), catheter in situ days ( P =0.281), and post-thrombotic syndrome ( P =1.000), except for activated partial thromboplastin time ( P =0.001).

CONCLUSIONS

With the early stop of this trial and limited data, it is difficult to draw a definitive conclusion about the efficacy of UFH on CRT. Meanwhile, considering the data from 6 months follow-up, in this population, asymptomatic CRT might resolve with no intervention.

Evaluation, analysis, and reporting of medication adherence for clinical trials of anticoagulants in children: guidance from the ISTH SSC Subcommittee on Pediatric and Neonatal Thrombosis and Hemostasis

In response to growing recognition that nonadherence prevents children, adolescents, and young adults from achieving the therapeutic benefits of anticoagulant medication, the International Society on Thrombosis and Haemostasis Scientific and Standardization Committee Subcommittee on Pediatric and Neonatal Thrombosis and Hemostasis convened a working party on medication adherence. The primary aim of this article was to synthesize recommendations from the larger adherence science literature to provide guidance regarding the classification, collection, and interpretation of anticoagulation adherence data. The secondary aim of this article was to evaluate the degree to which trials published from 2013 to 2023 adhered to these guidance recommendations. As less than half of all trials reported on adherence and none included all recommended elements, the proposed International Society on Thrombosis and Haemostasis Scientific and Standardization Committee guidance has the potential to enhance the rigor and reproducibility of pediatric anticoagulant research.

Efficacy and safety of antithrombotic therapy for preventing and treating pediatric thromboembolic disease: a systematic review

This review used traditional and network meta-analyses (NMA) to conduct a comprehensive study of antithrombotic therapies in children with thromboembolic disease. We searched the PubMed, Embase, Cochrane Library, Web of Science and ClinicalTrials.gov databases from their inception to 26 February, 2023. And we finally included 16 randomized controlled trials. In the prevention of thromboembolic events (TEs), the use of anticoagulants had a low risk of TEs (relative risk (RR) 0.73, 95% CI 0.56 to 0.94) and a high risk of minor bleeding (RR 1.43, 95% CI 1.09 to 1.86) compared with no anticoagulants. In the treatment of TEs, direct oral anticoagulants (DOACs) were not inferior to standard anticoagulation in terms of efficacy and safety outcomes. In NMA, rivaroxaban and apixaban showed the lowest risk for TEs and major or clinically relevant nonmajor bleeding. According to the overall assessment of efficacy and safety, dabigatran may be the best choice for children with thromboembolic disease. The results of our study will provide references and suggestions for clinical drug selection.

A systematic review and meta-analysis of the effectiveness of primary thromboprophylaxis in acute lymphoblastic leukemia during early-phase therapy including asparaginase or its prolonged form

Asparaginase is essential in the initial management of acute lymphoblastic leukemia (ALL) but frequently leads to venous thromboembolism (VTE). Using anticoagulants for primary VTE prevention has been studied with no consensus. We conducted a systematic literature search in PubMed, Scopus, and Web of science and performed random-effect meta-analysis using Mantel-Haenszel method in RevMan 5.4 to analyze primary pharmacological thromboprophylaxis during asparaginase treatment in early-phase (induction, consolidation, or intensification phase) therapy in patients with ALL with all ages and followed with subgroup analysis by age. Meta-analysis of 13 articles describing the effect of antithrombin supplementation in 1375 patients showed that antithrombin prophylaxis decreases the risk of VTE by 43% (RR, 0.57; 95% CI, 0.38 - 0.83; p=0.004), with mild heterogeneity (I2=35%, p=0.10) and moderate certainty by GRADE. 8 articles included for meta-analysis of low-molecular weight heparin (LMWH) treatment in 612 patients showed that it decreased the risk of VTE by nearly 40% (RR, 0.61; 95% CI, 0.45 - 0.81; p=0.00081), with minimal heterogeneity (I2=14%, p=0.31) but low certainty. Subgroup analysis showed that only prophylaxis with antithrombin supplementation significantly decreased the VTE rate in adult patients with moderate certainty. In pediatric patients, one nonrandomized prospective study showed that LMWH combined with antithrombin has a better thromboprophylaxis effect than antithrombin alone. In the PREVAPIX-ALL trial, prophylaxis with direct factor Xa inhibitor Apixaban did not benefit children younger than 18 years except for cases of obesity. We concluded that thromboprophylaxis with antithrombin is effective in ALL patients older than 18 years during the early phase of therapy, and LMWH combined with antithrombin supplementation might be effective for pediatric patients with ALL. Apixaban is effective in pediatric ALL patients with obesity and needs further study in other high-risk patients.

Antithrombin activity and central venous catheter-associated thrombosis in critically ill children at high risk of bleeding

BACKGROUND

Normalization of antithrombin activity may prevent catheter-associated thrombosis in critically ill children at high risk of bleeding.

OBJECTIVES

To characterize the temporal pattern of antithrombin activity, assess its association with catheter-associated thrombosis and clinically relevant bleeding, and evaluate its relationship with thrombin generation in these children.

METHODS

In this prospective cohort study, critically ill children <18 years old at high risk of bleeding with central venous catheter were eligible. Antithrombin activity and thrombin generation were measured from platelet-poor plasma and after in vitro antithrombin supplementation. Systematic surveillance ultrasound was performed to diagnose thrombosis. Children were followed for bleeding.

RESULTS

We enrolled 8 infants (median age: 0.2 years, IQR: 0.2, 0.3 years) and 72 older children (median age: 14.3 years, IQR: 9.1, 16.1 years). Mean antithrombin on the day of catheter insertion was 64 IU/dL (SD: 32 IU/dL) in infants and 83 IU/dL (SD: 35 IU/dL) in older children. Antithrombin normalized by the day of catheter removal. Thrombosis developed in 27 children, while 31 children bled. Thrombosis (regression coefficient: 0.008, 95% CI: -0.01, 0.03) and bleeding (regression coefficient: -0.0007, 95% CI: -0.02, 0.02) were not associated with antithrombin. Antithrombin was not correlated with in vivo change in endogenous thrombin potential (correlation coefficient: -0.07, 95% CI: -0.21, 0.08). In vitro supplementation reduced endogenous thrombin potential (correlation coefficient: -0.78; 95% CI: -0.95, -0.23).

CONCLUSION

These findings may not support normalization of antithrombin activity to prevent catheter-associated thrombosis in critically ill children at high risk of bleeding.

Apixaban versus no anticoagulation for the prevention of venous thromboembolism in children with newly diagnosed acute lymphoblastic leukaemia or lymphoma (PREVAPIX-ALL): a phase 3, open-label, randomised, controlled trial

BACKGROUND

Paediatric patients with acute lymphoblastic leukaemia or lymphoma are at increased risk of venous thromboembolism resulting in increased mortality and morbidity. We hypothesised that apixaban, a direct oral anticoagulant, would safely reduce venous thromboembolism in this patient population.

METHODS

PREVAPIX-ALL was a phase 3, open-label, randomised, controlled trial conducted in 74 paediatric hospitals in 9 countries. Participants aged 1 year or older to younger than 18 years with newly diagnosed acute lymphoblastic leukaemia (pre-B cell or T cell) or lymphoblastic lymphoma (B cell or T cell immunophenotype) and a central venous line in place throughout induction were randomly assigned 1:1 to standard of care (SOC, ie, no systemic anticoagulation) or weight-adjusted twice-daily apixaban during induction. Randomisation was performed centrally and stratified by age (those <10 years or those ≥10 years). Participants weighing 35 kg or less were administered 2·5 mg twice daily of apixaban as a 2·5 mg tablet, 0·5 mg tablets, or 0·4 mg/mL oral solution, while those weighing more than 35 kg were administered weight-adjusted prophylactic doses using 0·5 mg tablets or the 0·4 mg/mL oral solution twice daily. Primary outcomes were assessed by a blinded central adjudication committee. The primary efficacy outcome for the intention to treat population was the composite of symptomatic or clinically unsuspected venous thromboembolism, the primary safety outcome was major bleeding, and secondary safety outcomes included clinically relevant non-major (CRNM) bleeding. Patients were screened for venous thromboembolism by ultrasound and echocardiogram at the end of induction. The trial was registered with ClinicalTrials.gov (NCT02369653) and is now complete.

FINDINGS

Between Oct 22, 2015, and June 4, 2021, 512 participants were randomly assigned and included in analyses (222 [43%] female and 290 [57%] male; 388 [76%] White, 52 [10%] Asian, 24 [5%] Black or African American, and 48 [9%] other races; and 122 [24%] Hispanic or Latino ethnicity). During a median follow-up period of 27 days (IQR 26-28), 31 (12%) of 256 patients on apixaban had a composite venous thromboembolism compared with 45 (18%) of 256 participants receiving SOC (relative risk [RR] 0·69, 95% CI 0·45-1·05; p=0·080). Two major bleeding events occurred in each group (RR 1·0, 95% CI 0·14-7·01; p=1·0). A higher incidence of CRNM bleeding, primarily grade 1 or 2 epistaxis, occurred in the apixaban group (11 [4%] of 256 participants) compared with the SOC group (3 [1%] of 256; RR 3·67, 95% CI 1·04-12·97, p=0·030). The most frequent grade 3-5 adverse events in both groups were thrombocytopenia (n=28 for the apixaban group and n=20 for the SOC group) or platelet count decreased (n=49 and n=45), anaemia (n=77 and n=74), febrile neutropenia (n=27 and n=20), and neutropenia (n=16 and n=17) or neutrophil count decreased (n=22 and n=25). Five deaths occurred, which were due to infection (n=3 in the SOC group), cardiac arrest (n=1 in apixaban group), and haemorrhagic cerebral sinus vein thrombosis (n=1 in the SOC group). There was one apixaban-related death (coagulopathy and haemorrhage after cardiac arrest of unknown cause).

INTERPRETATION

PREVAPIX-ALL is, to our knowledge, the first trial assessing primary thromboprophylaxis using a direct oral anticoagulant in paediatric patients with acute lymphoblastic leukaemia or lymphoma. No statistically significant treatment benefit was identified in participants receiving apixaban. Major and CRNM bleeding were infrequent overall, but a higher incidence of CRNM bleeding (primarily epistaxis in younger children) occurred in participants receiving apixaban. For patients deemed to be at particularly high risk of thrombosis, PREVAPIX-ALL provides encouraging safety data for the use of apixaban in clinical settings in which the potential benefits are thought to outweigh the risk of bleeding.

FUNDING

Bristol Myers Squibb-Pfizer Alliance.

Subgroup analyses in venous thromboembolism trials reporting pharmacological interventions: A systematic review

INTRODUCTION

Randomized controlled trials (RCTs) that conduct subgroup analyses have the potential to provide information on treatment decisions in specific groups of patients from heterogeneous populations. Although we understand several factors can modify the incidence of venous thromboembolism (VTE) and the benefit/risk ratio of anticoagulation treatments, further evidence is warranted to show the heterogeneity of treatment effects in different subgroups of patients.

AIMS

The primary purpose was to evaluate the appropriateness and interpretation of subgroup analysis performed on VTE RCTs reporting pharmacological interventions.

MATERIALS AND METHODS

A systematic review of RCTs published between January 2017 and January 2022 was conducted. Claims of subgroup effects were evaluated with predefined criteria. High-quality claims of subgroup effect were further analyzed and discussed.

RESULTS

Overall, 28 RCTs with a generally low bias risk were included. The purposes of the treatments included pharmacologic thromboprophylaxis (17), therapeutic dose anticoagulation (9), and catheter-directed pharmacologic thrombolysis (2). The evaluated subgroup analyses generally presented: a high number of subgroup analyses reported, a lack of prespecification, and a lack of usage of statistical tests for interaction. The authors reported 13 claims of subgroup effect; only two were considered potentially reliable to represent heterogeneity in the direction or magnitude of treatment effect.

CONCLUSIONS

Subgroup analyses of VTE RCTs reporting pharmacologic interventions are generally methodologically poor. Most claims of subgroup effect did not meet critical criteria and lacked credibility. Clinicians in this field may proceed with scepticism when assessing claims of subgroup effects due to methodological concerns and misleading interpretations.

Updated guidance for efficacy and safety outcomes for clinical trials in venous thromboembolism in children: communication from the ISTH SSC Subcommittee on Pediatric and Neonatal Thrombosis and Hemostasis

Despite the growing number of pediatric antithrombotic clinical trials, standardized safety and efficacy outcome definitions for pediatric venous thromboembolism (VTE) clinical trials have not been updated since 2011. Many recent trials have adapted the recommended definitions, leading to heterogeneity in outcomes and limiting our ability to compare studies. The International Society on Thrombosis and Haemostasis Scientific and Standardization Subcommittee (SSC) on Pediatric and Neonatal Thrombosis and Hemostasis organized a Task Force to update the efficacy and safety outcome definitions for pediatric VTE clinical trials. The outcome definitions used in the recent pediatric antithrombotic trials, definitions recommended for adult studies, and regulatory guidelines were summarized and reviewed by the Task Force as the basis for this updated guidance. Major updates to the efficacy outcomes include the removal of VTE-related mortality as a part of a composite primary outcome and explicit inclusion of all deep venous anatomic sites. Safety outcomes were updated to include a new bleeding severity category: patient important bleeding, no intervention, which encompasses bleeding for which a patient seeks care but there is no change in management. Menstrual bleeding can now be included in any bleeding category when the criteria are met. We hope that these updated outcome definitions will allow the investigators to focus on clinically relevant and patient-important outcomes and provide standardization to facilitate continued high-quality evidence for the use of antithrombotic therapies in children.

Incidence and Risk Factors of Venous Thromboembolism in Childhood Acute Lymphoblastic Leukaemia - a Population-Based Analysis of the Austrian Berlin-Frankfurt-Münster (BFM) Study Group

Venous thromboembolism (VTE) is a well-known complication of the treatment of pediatric acute lymphoblastic leukemia (ALL). We analyzed 1026 ALL patients 1-18-years-old, who were enrolled into the AIEOP-BFM ALL 2000 or 2009 studies in Austria, with regard to the incidence and risk factors of VTE. The 2.5-year cumulative incidence (CI) of VTE ≥ grade 2 was 4%±1% (n = 36/1026). Twenty VTE (56%) were found in the central nervous system (19 cerebral venous sinus and 1 cortical vein thrombosis), and 16 (44%) at other sites (7 deep vein thromboses (DVT) of the lower extremity, 4 DVT of the upper extremity, 4 central venous line-thromboses, 1 pulmonary embolism). Most VTE occurred during induction and early consolidation therapy (81%) and were associated with L-asparaginase within 4 and corticosteroids withing 1 week(s) preceding the event (89 and 86%, respectively). In multivariable analysis, two independent risk factors were found. Patients 10-18-years-old had an increased (hazard-ratio: 2.156, p = 0.0389), whereas treatments in trial AIEOP-BFM ALL 2009 had a lower risk for VTE (hazard-ratio: 0.349, p = 0.0270). In conclusion, the 2.5-year CI of VTE among our pediatric patient cohort was <5% and adolescent age was the main patient-related risk factor. This older age group might benefit from primary prophylactic measures.

Pediatric cancer-associated thrombosis: Analysis from a tertiary care cancer center in India

BACKGROUND AND AIMS

Thrombotic events (TEs) have been extensively studied in adult cancer patients, but data in children are limited. We prospectively analyzed pediatric cancer-associated thrombosis (PCAT) in children with malignancies.

METHODS

Children below 15 years of age with confirmed malignancies, treated at a large tertiary cancer center in India from July 2015 to March 2020 developing any TE were eligible. A standardized approach for detection and management was followed. Data were collected after informed consent.

RESULTS

Of 6132 eligible children, 150 (2.44%) had 152 TEs, with median age 8.5 years and male:female of 1.83:1. Most TEs occurred on chemotherapy: 111 (74.0%). The most common site was central nervous system (CNS) 59 (39.3%), followed by upper-limb venous system 37 (24.7%). Hemato-lymphoid (HL) malignancies were more prone to PCAT than solid tumors (ST) (incidence 3.23% vs. 1.58%; odds ratio [OR] = 2.06, 95% confidence interval [CI] [1.36-2.88]; p < .001). Malignancies associated with PCAT were acute lymphoblastic leukemia (ALL) 2.94%, acute myeloid leukemia (AML) 6.66%, and non-Hodgkin lymphomas 5.35%. Response imaging done in 106 (70.7%) children showed complete to partial resolution in almost 90% children. Death was attributable to TE in seven (4.66%) children. Age above 10 years (OR 2.33, 95% CI [1.59-3.41]; p < .001), AML (OR 4.62, 95% CI [1.98-10.74]; p = .0062), and non-Hodgkin lymphoma (OR 4.01, 95% CI [1.15-14.04]; p = .029) were significantly associated with TEs. In ALL, age more than 10 years (OR 1.86, 95% CI [1.06-3.24]; p < .03), T-ALL (OR 3.32, 95% CI [1.69-6.54]; p = .001), and intermediate-risk group (OR 4.97, 95% CI [1.12-22.02]; p = .035) were significantly associated with thrombosis. The 2-year event-free survival (EFS) for HL malignancies with PCAT was 55.3% versus 72.1% in those without PCAT (p = .05), overall survival (OS) being 84.6% versus 80.0% (p = .32).

CONCLUSION

Incidence of PCAT was 2.4%, and occurred predominantly in older children with hematolymphoid malignancies early in treatment. Most resolved completely with low molecular weight heparin (LMWH) and mortality was low. In hematolymphoid malignancies, PCAT reduce EFS, highlighting the need for prevention.

Asparaginase: How to Better Manage Toxicities in Adults

PURPOSE OF REVIEW

This review aims to help oncologists who predominantly treat adults better understand and manage asparaginase associated toxicities and prevent unnecessary discontinuation or reluctance of its use.

RECENT FINDINGS

Given the data supporting the benefit of incorporating multiple doses of asparaginase in pediatric type regimens, it is prudent to promote deeper understanding of this drug, particularly its toxicities, and its use so as to optimize treatment of ALL. Although asparaginase is associated with a variety of toxicities, the vast majority are not life threatening and do not preclude repeat dosing of this important drug. Understanding the pharmacology and toxicity profile of asparaginase is critical to dosing asparaginase appropriately in order to minimize these toxicities.

Asparaginase toxicity in Hispanic adult and pediatric patients with acute lymphoblastic leukemia: current understanding

INTRODUCTION

Asparaginase is essential to chemotherapy regimens for acute lymphoblastic leukemia (ALL). Survival of patients with ALL has improved since incorporating asparaginase into chemotherapy backbones. Hispanic patients have a higher incidence of ALL than other ethnicities and suffer inferior outcomes. The inferior outcome of Hispanics is due to several factors, including the increased incidence of high-risk genetic subtypes and susceptibility to treatment-related toxicity.

AREAS COVERED

We summarize the current knowledge of asparaginase-related toxicity by comparing their incidence between Hispanic and non-Hispanic patients. These toxicities include hypersensitivity, hepatotoxicity, pancreatitis, thrombosis, and hypertriglyceridemia. The PubMed database and Google Scholar were used to search for this review from October 2022 to June 2023.

EXPERT OPINION

Except for hepatotoxicity and hypertriglyceridemia secondary to asparaginase-based treatments, which may develop more frequently among Hispanic patients with ALL, other toxicities were comparable between Hispanic and non-Hispanic patients. Nevertheless, studies with larger cohorts and more accurate capturing of Hispanic ethnicity should be conducted to fill the gaps in the current knowledge.

Appendix to the Society of Interventional Radiology Consensus Guidelines for the Periprocedural Management of Thrombotic and Bleeding Risk in Patients Undergoing Percutaneous Image-Guided Interventions: Pediatric Considerations

PURPOSE

To provide guidance on the use of anticoagulant and antithrombotic agents in pediatric patients undergoing interventional radiology procedures.

MATERIALS AND METHODS

A multidisciplinary writing group conducted a comprehensive literature search to identify studies on the topic of interest. Recommendations were developed for procedural risk and medication dosage and withholding. A modified Delphi technique was used to achieve consensus agreement on the recommendations.

RESULTS

A total of 24 studies, including systematic reviews and meta-analyses, randomized controlled trials, and prospective and retrospective cohort studies, were identified as relevant. The expert writing group agreed on procedural risk categorization, laboratory testing thresholds, and medication dosage and withholding recommendations specific to pediatric practice. They additionally described the nuances of anticoagulation in clinical conditions specific to pediatrics.

CONCLUSIONS

The Society of Interventional Radiology recommends following the guidance provided in the document when developing multidisciplinary management protocols for anticoagulation and antithrombotic treatment in pediatric patients undergoing interventional radiology procedures.

SOHO State of the Art Updates and Next Questions | Asparaginase-Understanding and Overcoming Toxicities in Adults with ALL

The adoption of pediatric-inspired regimens in young adults with newly diagnosed acute lymphoblastic leukemia (ALL) has significantly improved their survival outcomes. Pediatric-inspired regimens in ALL rely profoundly on delivering adequate dosing of non-myelosuppressive drugs of which asparaginase, a bacterial derived agent, is a key component. Asparaginase therapy is associated with a spectrum of unique toxicities that are observed more frequently in adult patients compared to children with ALL, and this observation has contributed to the reluctance of adult oncologists to administer the drug to their patients. Understanding the breadth of asparaginase toxicity and the associated risk factors may help in preventing severe manifestations and allow safer treatment for adults with ALL. In this review, we will discuss the different formulations of asparaginase and the appropriate dosing in adults with ALL. We will further discuss the frequency and risk factors for individual toxicities of asparaginase along with strategies for their prevention and management.

Management Practices for Asparaginase-associated Coagulopathy: A Survey of Pediatric Oncologists

BACKGROUND

Coagulopathy and thrombosis are well-described complications of asparaginase therapy. However, treatment practices in pediatric hematology/oncology (PHO) patients vary widely as evidence-based guidelines for clinical management of these complications in this population are lacking.

OBJECTIVE

The objective of this study was to assess management practices of asparaginase-related coagulopathy by pediatric hematologist/oncologist attending physicians.

DESIGN/METHOD

Email survey sent to 2327 PHO physicians primarily practicing in the United States.

RESULTS

Two hundred eighty-five (12.2%) attending physicians completed the survey. Only 4.6% (n=13/285) routinely prescribe prophylactic anticoagulation during induction chemotherapy for leukemia. Slightly more than half (n=145/250, 50.9%) of all providers perform baseline coagulation studies. Most providers that were surveyed (n=185/285, 64.9%) only replete coagulant factors if the patient experiences bleeding or bruising. One hundred thirty (n=130/285, 45.6%) physicians replace low fibrinogen. The median fibrinogen replacement was 100 mg/dL (range: 40 to 200 mg/dL) with the median target of at least 100 mg/dL (range: 50 to 200 mg/dL). A minority of physicians (n=39/250, 13.7%) replace low antithrombin. The median antithrombin cutoff activity level was 60% (range: 40% to 100%) with a median target of 75% (range: 40% to 125%).

CONCLUSIONS

There is a significant variation in PHO physician practices for monitoring and management of asparaginase-associated hemostatic derangements. Evidence-based guidelines have the potential to standardize practices.

A survey on thromboprophylaxis and coagulation assessment in children and young adults with acute lymphoblastic leukaemia (ALL) in the Nordic and Baltic countries: Different practices of assessment and management

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.

Prophylactic Enoxaparin Against Catheter-Associated Thrombosis in Postoperative Cardiac Children: An Interrupted Time Series Analysis

OBJECTIVES

The effectiveness of pharmacologic prophylaxis against catheter-associated thrombosis in children is unclear. We evaluated the compliance and outcomes associated with a prophylactic enoxaparin protocol in postoperative cardiac children.

DESIGN

The protocol was implemented as a quality improvement initiative and then analyzed using interrupted time series method. Data collected from November 2014 to December 2018 were divided into preprotocol (period 1), protocol implementation (period 2), and protocol revision (period 3).

SETTING

A 12-bed academic pediatric cardiac ICU.

PATIENTS

Children less than or equal to 18 years old with congenital heart disease admitted postoperatively with central venous catheter in situ for greater than or equal to 1 day.

INTERVENTIONS

Before 2016, prophylactic enoxaparin was administered according to physician preference. In January 2016, an enoxaparin protocol was implemented with a goal anti-Xa range of 0.25-0.49 international units/mL. Protocol was revised in February 2017 to increase the starting dose by 25% for infants less than 1 year old.

MEASUREMENTS AND MAIN RESULTS

We analyzed 780 hospitalizations from 636 children. Median percentage of catheter-days on prophylactic enoxaparin was 33% (interquartile range [IQR], 23-47%), 42% (IQR, 30-51%), and 38% (IQR, 35-52%) in periods 1-3, respectively. Percentage of catheter-days on enoxaparin showed immediate increase of 90% (95% CI, 17-210%) between periods 1 and 2 and sustained increase of 2% (95% CI, 0.3-4%) between periods 2 and 3. Median rates of thrombosis per 1,000 catheter-days were 5.8 (IQR, 0-9.3), 3.8 (IQR, 0-12), and 0 (IQR, 0-5.3) in periods 1-3, respectively. Rate of thrombosis showed immediate decrease of 67% (95% CI, 12-87%) between periods 1 and 2 and sustained decrease of 11% (95% CI, 2-18%) between periods 1 and 3.

CONCLUSIONS

The temporal association between increase in percentage of catheter-days on enoxaparin and decrease in rate of thrombosis suggests the effectiveness of prophylactic enoxaparin.

Cranial MRI in Childhood Acute Leukemia during Treatment and Follow-Up Including the Impact of Intrathecal MTX-A Single-Center Study and Review of the Literature

Due to high survival rates, long-term sequelae, especially neurotoxicity, need to be considered in childhood acute leukemias. In this retrospective analysis of morphologic changes of the brain in children treated for acute leukemias, we included 94 patients (77 ALL, 17 AML; 51 male, 43 female; median age: 5 years) from a single center. We analyzed 170 cranial MRI scans (T2, FLAIR axial) for morphologic alterations of the brain and variations of the ventricular width (GDAH). In addition, the corresponding literature was reviewed. More than 50% of all patients showed cerebral pathomorphologies (CP). They were seen more often in children with ALL (55.8%), ≤ 6 years of age (60.8%), in relapse (58.8%) or after CNS irradiation (75.0%) and included white matter changes, brain atrophy, sinus vein thrombosis and ischemic events. GDAH significantly enlarged mainly in children up to 6 years, with relapse, high-risk leukemias or ALL patients. However, GDAH can normalize again. The number of intrathecal Methotrexate applications (≤12 vs. >12) showed no correlation to morphologic alterations besides a significant increase in GDAH (−0.3 vs. 0.9 mm) between the first and last follow-up MRI in ALL patients receiving >12 ith. MTX applications. The role of ith. MTX on CP needs to be further investigated and correlated to the neurocognitive outcome of children with acute leukemias.

Supportive methods for childhood acute lymphoblastic leukemia then and now: A compilation for clinical practice

Survival of childhood acute lymphoblastic leukemia has significantly improved over the past decades. In the early years of chemotherapeutic development, improvement in survival rates could be attained only by increasing the cytostatic dose, also by modulation of the frequency and combination of chemotherapeutic agents associated with severe short- and long-time side-effects and toxicity in a developing child's organism. Years later, new treatment options have yielded promising results through targeted immune and molecular drugs, especially in relapsed and refractory leukemia, and are continuously added to conventional therapy or even replace first-line treatment. Compared to conventional strategies, these new therapies have different side-effects, requiring special supportive measures. Supportive treatment includes the prevention of serious acute and sometimes life-threatening events as well as managing therapy-related long-term side-effects and preemptive treatment of complications and is thus mandatory for successful oncological therapy. Inadequate supportive therapy is still one of the main causes of treatment failure, mortality, poor quality of life, and unsatisfactory long-term outcome in children with acute lymphoblastic leukemia. But nowadays it is a challenge to find a way through the flood of supportive recommendations and guidelines that are available in the literature. Furthermore, the development of new therapies for childhood leukemia has changed the range of supportive methods and must be observed in addition to conventional recommendations. This review aims to provide a clear and recent compilation of the most important supportive methods in the field of childhood leukemia, based on conventional regimes as well as the most promising new therapeutic approaches to date.

Hemostatic and thrombotic disorders in the pediatric patient

This review focuses on significant advances in the field of pediatric hemostasis and thrombosis, with a focus on published studies within the past decade. The evaluation and management of patients with excessive bleeding remain cornerstones of consultative hematology. We will describe the development of validated bleeding assessment tools relevant to pediatric practice, laboratory advances in the evaluation of von Willebrand disease, and a shift in clinical practice regarding the interpretation of normal coagulation studies in patients with significant bleeding phenotypes. There have also been critical advances in the management of hemostatic disorders. This review highlights new treatment paradigms in hemophilia and the rise of multidisciplinary medical homes for women living with bleeding disorders. Given the continued increase in the incidence of thrombosis, particularly in the hospital setting, a full call to arms against pediatric venous thromboembolism is now essential. We will describe recently completed clinical trials of direct oral anticoagulants in children and adolescents and ongoing work to elucidate the appropriate duration of therapy for children with provoked thrombosis. Recent work regarding the prevention of pediatric venous thromboembolism is highlighted, including studies of thromboprophylaxis and the development of risk prediction models for hospital-acquired thrombosis. Finally, we review advances in our understanding of thrombotic sequelae and the need for continued refinement of our evaluation tools. Despite the significant advances in pediatric hemostasis and thrombosis over the past decade, many unanswered questions remain for the next generation of investigators.

Predictors of thrombosis in children receiving therapy for acute lymphoblastic leukemia: Results from Dana-Farber Cancer Institute ALL Consortium trial 05-001

BACKGROUND/OBJECTIVES

Although thromboembolism (TE) is a serious complication in patients with acute lymphoblastic leukemia (ALL), thromboprophylaxis is not commonly used due to the inherent bleeding risk in this population. Identifying prothrombotic risk factors will help target thromboprophylaxis to those at highest thrombotic risk. We aimed to define predictors and the impact of TE on ALL outcome in children (1-18 years) treated on the Dana-Farber Cancer Institute ALL 05-001 trial.

METHODS

Clinical and laboratory data including TE events were prospectively collected. PCR-based allelic discrimination assay identified single-nucleotide polymorphisms (SNP) for prothrombin G20210A (rs1799963) and Factor V G1691A (rs6025). Univariate and multivariable competing risk regression models evaluated the effect of diagnostic clinical (age, sex, body mass index, ALL-immunophenotype, risk group) and laboratory variables (presenting leukocyte count, blood group, SNPs) on the cumulative incidence of TE. Cox regression modeling explored the impact of TE on survival.

RESULTS

Of 794 patients [median age 4.97 (range, 1.04-17.96) years; males 441], 100 developed TE; 25-month cumulative incidence 13.0% (95% CI, 10.7%-15.5%). Univariate analyses identified older age (≥10 years), presenting leucocyte count, T-ALL, high-risk ALL, and non-O blood group as risk factors. Age and non-O blood group were independent predictors of TE on multivariable regression; the blood group impact being most evident in patients 1-5 years of age (P = 0.011). TE did not impact survival. Induction TE was independently associated with induction failure (OR 6.45; 95% CI, 1.64-25.47; P = 0.008).

CONCLUSION

We recommend further evaluation of these risk factors and consideration of thromboprophylaxis for patients ≥10 years (especially those ≥15 years) when receiving asparaginase.

2022 international clinical practice guidelines for the treatment and prophylaxis of venous thromboembolism in patients with cancer, including patients with COVID-19

The International Initiative on Thrombosis and Cancer is an independent academic working group of experts aimed at establishing global consensus for the treatment and prophylaxis of cancer-associated thrombosis. The 2013, 2016, and 2019 International Initiative on Thrombosis and Cancer clinical practice guidelines have been made available through a free, web-based mobile phone application. The 2022 clinical practice guidelines, which are based on a literature review up to Jan 1, 2022, include guidance for patients with cancer and with COVID-19. Key recommendations (grade 1A or 1B) include: (1) low-molecular-weight heparins (LMWHs) for the initial (first 10 days) treatment and maintenance treatment of cancer-associated thrombosis; (2) direct oral anticoagulants for the initial treatment and maintenance treatment of cancer-associated thrombosis in patients who are not at high risk of gastrointestinal or genitourinary bleeding, in the absence of strong drug-drug interactions or of gastrointestinal absorption impairment; (3) LMWHs or direct oral anticoagulants for a minimum of 6 months to treat cancer-associated thrombosis; (4) extended prophylaxis (4 weeks) with LMWHs to prevent postoperative venous thromboembolism after major abdominopelvic surgery in patients not at high risk of bleeding; and (5) primary prophylaxis of venous thromboembolism with LMWHs or direct oral anticoagulants (rivaroxaban or apixaban) in ambulatory patients with locally advanced or metastatic pancreatic cancer who are treated with anticancer therapy and have a low risk of bleeding.

Venous thromboembolism in pediatric patients with acute lymphoblastic leukemia under chemotherapy treatment. Risk factors and usefulness of thromboprophylaxis. Results of LAL-SEHOP-PETHEMA-2013

INTRODUCTION

Symptomatic venous thromboembolism (VTE) is diagnosed in 3%-14% of patients during pediatric acute lymphoblastic leukemia (ALL) therapy. There are well-known risk factors, but the role of others as inherited thrombophilia is still controversial. Prophylaxis with low molecular weight heparin (LMWH) has been described, but its use is not globally accepted.

METHODS

A retrospective multicentric study in ALL patients 1-18 years old following SEHOP-PETHEMA-2013 treatment guideline was performed to evaluate VTE rate, anticoagulant treatment, outcome, risk factors, and safety and usefulness of LMWH administration as primary thromboprophylaxis in children with inherited thrombophilia.

RESULTS

A total of 652 patients were included in the study. VTE incidence was 8.7%. Most of the cases occurred during induction therapy associated with central venous catheter. Univariant analysis showed that family history of thrombosis, presence of mediastinal mass, high-risk treatment group, and inherited thrombophilia were statistically significant risk factors. LMWH administration seemed to decrease VTE rate in patients with inherited thrombophilia and those with T-cell ALL phenotype.

CONCLUSION

Most of the VTE cases occurred in patients without inherited thrombophilia, but when it is present, the VTE risk is higher. LMWH administration was useful to decrease VTE in these patients.

Anticoagulation in Pediatric Patients

Special aspects of anticoagulation in children include the different epidemiology of thrombosis, developmental changes in the coagulation system, age-dependent pharmacokinetics of anticoagulants, risk of bleeding, and practical hurdles to anticoagulation. The classical anticoagulants so far used in children have several limitations, resulting in the need for regular monitoring. The pharmacological properties of direct oral anticoagulants (DOACs) and the special challenges of anticoagulation in children make the DOACs particularly attractive for children. All DOACs have pediatric development programs, targeting various indications for prevention and treatment of thrombosis. Child-appropriate formulations have been developed, age-specific dosing information generated, and safety and efficacy evaluated in ongoing phase 3 trials. Rivaroxaban and dabigatran have already been authorized for children for treatment of acute venous thrombosis and for extended secondary prevention. Their safety and efficacy have been demonstrated comparable to that of standard-of-care anticoagulants, without need for monitoring. Further studies are ongoing, which are expected to lead to pediatric authorizations of DOACs for primary venous thromboembolic event prevention in some high-risk settings. More real-life data will be necessary from postmarketing studies and registries to complement the evidence base for DOAC use in children, particularly in the youngest age groups and special disease populations.

Thrombosis Complications in Pediatric Acute Lymphoblastic Leukemia: Risk Factors, Management, and Prevention: Is There Any Role for Pharmacologic Prophylaxis?

Pediatric acute lymphoblastic leukemia (ALL) has achieved close to 90% cure rates through extensive collaborative and integrative molecular research, clinical studies, and advances in supportive care. Despite this high achievement, venous thromboembolic complications (VTE) remain one of the most common and potentially preventable therapy-associated adverse events in ALL. The majority of thromboses events involve the upper central venous system which is related to the use and location of central venous catheters (CVC). The reported rates of symptomatic and asymptomatic CVC-related VTE range from 2.6 to 36.7% and 5.9 to 43%, respectively. Thrombosis can negatively impact not only disease-free survival [e.g., therapy delays and/or interruption, omission of chemotherapy agents (e.g., asparaginase therapy)] but also can result in long-term adverse effects that can impair the quality of life of ALL survivors (e.g., post-thrombotic syndrome, central nervous system (CNS)-thrombosis related complications: seizures, neurocognitive deficits). In this review, will discuss thrombosis pathophysiology in pediatric ALL, risk factors, treatment, and prevention strategies. In addition, the recently published clinical efficacy and safety of direct oral anticoagulants (DOACs) use in thrombosis treatment, and their potential role in primary/secondary thrombosis prevention in pediatric patients with ALL will be discussed. Future clinical trials involving the use of these novel oral anticoagulants should be studied in ALL not only for primary thrombosis prevention but also in the treatment of thrombosis and its secondary prevention. These future research findings could potentially extrapolate to VTE prevention strategies in other pediatric cancer diagnoses and children considered at high risk for VTE.

Challenges in Management of VTE in Children With Cancer: Risk Factors and Treatment Options

Venous thromboembolism (VTE) occurs in 2.1 to up to 50% of children with cancer and contributes to long term morbidity as well as early mortality in this population. Pediatric patients with malignancy are predisposed to VTE due to the prothrombotic nature of cancer and its associated coagulopathies as well as chemotherapeutic agents, use of central venous catheters, surgery, radiotherapy, and concomitant thrombophilia. Management of thrombosis in this population is challenging due to concomitant thrombocytopenia, associated bleeding risks, concurrent co-morbidities, and toxicities of therapy. The aim of this paper is to highlight clinically relevant issues and management dilemmas using clinical vignettes. We review the clinical significance of asymptomatic and symptomatic thrombosis, examine the various options for asparaginase-associated thrombosis, address the role and controversies of direct oral anticoagulants, and describe our approach to managing anticoagulation therapy in the context of chemotherapy-induced thrombocytopenia.

Somatic homozygous loss of SH2B3, and a non-Robertsonian translocation t(15;21)(q25.3;q22.1) with NTRK3 rearrangement, in an adolescent with progenitor B-cell acute lymphoblastic leukemia with the iAMP21

Intrachromosomal amplification of chromosome 21 (iAMP21) occurs in ∼2% of B-cell acute lymphoblastic leukemia (ALL) and is considered to confer a poor prognosis. The relapse risk is associated with therapy intensity, suggesting that other somatic mutations may influence iAMP21-ALL prognosis. This abnormality is characterized by multiple copies of the RUNX1 gene in chromosome 21 and appears to arise through multiple breakage-fusion bridge cycles and chromothripsis. Rob(15;21) or a ring chromosome 21 have been associated with an increased risk for iAMP21-ALL, suggesting that constitutional genetic abnormalities may also drive leukemogenesis. Here we describe homozygous deletion of the SH2B3 gene, chromothripsis of chromosome 21, and a non-Robertsonian somatic t(15;21)(q25.3;q22.1) with NTRK3 gene rearrangement in an adolescent with iAMP21-B-ALL. Molecular cytogenetic studies detected iAMP21 with aCGH analysis revealing further genomic imbalances. The RT-qPCR analysis detected elevated expression levels of RUNX1 (68-fold) and reduced expression of CDK6 (0.057-fold). Studies with constitutive cells collected from mouth swabs showed that SH2B3 biallelic deletion was a somatic alteration occurring during clonal evolution. The identification of novel secondary genetic changes was valuable to discuss sporadic iAMP21 leukemogenic mechanisms. For the first time, we show a t(15;21)(q25.3;q22.1) with NTRK3 rearrangement in an adolescent with iAMP21-ALL.

L-Asparaginase Toxicity in the Treatment of Children and Adolescents with Acute Lymphoblastic Leukemia

Asparaginase is a basic component of chemotherapy in pediatric acute lymphoblastic leukemia (ALL) and has played a crucial role in improving the long-term survival of this disease. The objectives of this retrospective study were to elucidate the toxicity profile associated with asparaginase in children and adolescents with ALL, to analyze the impact of each type of toxicity on long-term outcomes, and to identify risk factors. We analyzed the medical charts of 165 patients diagnosed with ALL at Sf. Maria Iasi Children’s Hospital from 2010 to 2019 and treated according to a chemotherapeutic protocol containing asparaginase. The median duration of follow-up was 5 years (0.1–11.5 years). Groups of patients with specific types of toxicity were compared to groups of patients without toxicity. We found the following incidence of asparaginase-associated toxicity: 24.1% clinical hypersensitivity, 19.4% hepatotoxicity, 6.7% hypertriglyceridemia, 4.2% hyperglycemia, 3.7% osteonecrosis, 3% pancreatitis, 2.4% thrombosis, and 1.2% cerebral thrombosis. Overall, 82 patients (49.7%) had at least one type of toxicity related to asparaginase. No type of toxicity had a significant impact on overall survival or event-free survival. Being older than 14 years was associated with a higher risk of osteonecrosis (p = 0.015) and hypertriglyceridemia (p = 0.043) and a lower risk of clinical hypersensitivity (p = 0.04). Asparaginase-related toxicity is common and has a varied profile, and its early detection is important for realizing efficient and appropriate management.

SOHO State of the Art Updates and Next Questions: Management of Asparaginase Toxicity in Adolescents and Young Adults with Acute Lymphoblastic Leukemia

A wider use of L-asparaginase in the treatment of children with acute lymphoblastic leukemia has improved cure rates during recent decades and hence led to introduction of pediatric-inspired treatment protocols for adolescents and young adults. In parallel, a range of burdensome, often severe and occasionally life-threatening toxicities have become frequent, including hypersensitivity, hepatotoxicity, hypertriglyceridemia, thromboembolism, pancreatitis, and osteonecrosis. This often leads to truncation of asparaginase therapy, which at least in the pediatric population has been clearly associated with a higher risk of leukemic relapse. Many of the asparaginase induced toxicities are far more common in older patients, but since their relapse rate is still unsatisfactory, the decision to discontinue asparaginase therapy should balance the risk of toxicity with continued asparaginase therapy against the risk of relapse in the individual patient. The underlying mechanisms of most of the asparaginase induced side effects are still unclear. In this review we address the individual toxicities, known risk factors, and their clinical management.

Efficacy of Early Prophylaxis Against Catheter-Associated Thrombosis in Critically Ill Children: A Bayesian Phase 2b Randomized Clinical Trial

OBJECTIVES

We obtained preliminary evidence on the efficacy of early prophylaxis on the risk of central venous catheter-associated deep venous thrombosis and its effect on thrombin generation in critically ill children.

DESIGN

Bayesian phase 2b randomized clinical trial.

SETTING

Seven PICUs.

PATIENTS

Children less than 18 years old with a newly inserted central venous catheter and at low risk of bleeding.

INTERVENTION

Enoxaparin adjusted to anti-Xa level of 0.2-0.5 international units/mL started at less than 24 hours after insertion of central venous catheter (enoxaparin arm) versus usual care without placebo (usual care arm).

MEASUREMENTS AND MAIN RESULTS

At the interim analysis, the proportion of central venous catheter-associated deep venous thrombosis on ultrasonography in the usual care arm, which was 54.2% of 24 children, was significantly higher than that previously reported. This resulted in misspecification of the preapproved Bayesian analysis, reversal of direction of treatment effect, and early termination of the randomized clinical trial. Nevertheless, with 30.4% of 23 children with central venous catheter-associated deep venous thrombosis on ultrasonography in the enoxaparin arm, risk ratio of central venous catheter-associated deep venous thrombosis was 0.55 (95% credible interval, 0.24-1.11). Including children without ultrasonography, clinically relevant central venous catheter-associated deep venous thrombosis developed in one of 27 children (3.7%) in the enoxaparin arm and seven of 24 (29.2%) in the usual care arm (p = 0.02). Clinically relevant bleeding developed in one child randomized to the enoxaparin arm. Response profile of endogenous thrombin potential, a measure of thrombin generation, was not statistically different between trial arms.

CONCLUSIONS

These findings suggest the efficacy and safety of early prophylaxis that should be validated in a pivotal randomized clinical trial.

Thrombosis is associated with worse survival in children with acute lymphoblastic leukemia: A report from CYP-C

There are conflicting data about whether the development of cancer-associated thrombo-embolism (TE) negatively impacts survival in children. The objective was to determine whether TE during treatment was associated with overall survival (OS) and event-free survival (EFS) in children with acute lymphoblastic leukemia (ALL). We performed a population-based retrospective cohort study using the Cancer in Young People-Canada registry. Children <15 years of age were diagnosed with de novo ALL (2000-2016). The primary exposure variable was radiologically-confirmed thrombo-embolism requiring medical intervention. Multivariable Cox regression models were used to determine the impact of thrombo-embolism on survival, where TE was time-dependent. We included 2006 children (median age: 4 years, 88.5% precursor B-cell ALL). Thrombo-embolism occurred in 113 patients (5.6%), at a median time of 107 days (interquartile range: 35-184 days) after ALL diagnosis. Among standard/low-risk patients, 41/1165 (3.5%) developed TE while among high/very high-risk patients, 72/841 (8.6%) developed TE. Patients with TE had a significantly worse OS (adjusted HR [aHR] of death: 2.61, 95% CI: 1.62-4.22, p < 0.001) and EFS (aHR of an event [death, relapse, second malignancy]: 2.03, 95% CI: 1.35-3.05, p = 0.001), compared with patients without TE. No statistically significant difference was seen in standard/low risk ALL for OS and EFS, but TE was associated with a significantly lower OS and EFS in children with high/very high-risk ALL (aHR of death: 2.90, 95% CI: 1.79-4.72, p < 0.001; aHR of an event: 2.02, 95% CI: 1.30-3.12, p = 0.002). Thus, TE led to a statistically significant reduction in OS and EFS in children with high risk/very high-risk leukemia.

Comparison of CALGB 10403 (Alliance) and COG AALL0232 toxicity results in young adults with acute lymphoblastic leukemia

Adolescents and young adults (AYAs) with acute lymphoblastic leukemia have improved outcomes when treated with pediatric-inspired regimens. CALGB 10403 was the largest prospective study to evaluate the feasibility of using a pediatric regimen in AYAs with acute lymphoblastic leukemia up to 40 years of age. This article presents the toxicity events observed in the CALGB 10403 study and compares these toxicities vs those observed among AYAs treated on the same arm of the companion Children's Oncology Group (COG) AALL0232 study. Toxicities in CALGB 10403 were similar to those observed in COG AALL0232. Some grade 3 to 4 adverse events were more often reported in CALGB 10403 compared with COG AALL0232 (hyperglycemia, hyperbilirubinemia, transaminase elevation, and febrile neutropenia). Adverse events correlated with body mass index ≥30 kg/m2 and some with increasing age. The mortality rate in CALGB 10403 was low (4%) and similar to that in the COG AALL0232 trial. A caveat to this analysis is that only 39% of CALGB 10403 patients completed all planned protocol treatment. In COG AALL0232, although 74% of patients aged <18 years completed treatment, only 57% of patients aged ≥18 years completed treatment. This scenario suggests that issues associated with age and treating physician may be a factor. Due to its improved survival rates compared with historical controls, the CALGB 10403 regimen is now a standard of care. The hope is that the rate of protocol completion will increase as more familiarity is gained with this regimen. These trials were registered at www.clinicaltrials.gov as #NCT00558519 (CALGB 10403) and #NCT00075725 (COG AALL0232).

Pegaspargase in Practice: Minimizing Toxicity, Maximizing Benefit

PURPOSE OF REVIEW

The incorporation of pegaspargase in chemotherapy regimens has significantly improved the prognosis of ALL in adults. However, pegaspargase use poses many challenges due to its unique toxicity profile. Here, we review pegaspargase's most clinically significant toxicities, and provide guidance for their prevention and management in order to avoid unnecessary drug discontinuation and achieve maximum clinical benefit.

RECENT FINDINGS

Clinically significant toxicities of pegaspargase include thrombosis, hypersensitivity and inactivation, hepatotoxicity, pancreatitis, and hypertriglyceridemia. The majority of these toxicities are temporary, nonfatal, and can be managed supportively without permanent pegaspargase discontinuation. Special attention should be paid to inactivation, which can lead to treatment failure, as well as pancreatitis, which necessitates complete cessation of asparaginase therapy. The question of how to best proceed in patients who cannot tolerate pegaspargase remains unanswered, and is an important area of future investigation. Pegaspargase is an essential component of the pediatric-inspired regimens that have improved survival in adult ALL. Although pegaspargase's toxicity profile is unique, it is also highly manageable and should not be a barrier to achieving maximum clinical benefit using this drug.

The incidence and risk factors for venous thromboembolism in adolescent and young adult oncology patients

BACKGROUND

Venous thromboembolism (VTE) is a known complication among pediatric and adult cancer patients. Adolescent and young adult oncology (AYAO) patients have unique biological and physiological characteristics that make them distinct from other populations. Our objective was to study the VTE incidence, risk factors, and outcomes, which have been understudied in this population.

PROCEDURE

A retrospective case-control study was conducted on AYAO participants with new or relapsed cancer and an imaging confirmed VTE from January 2011 to November 2016 at our institution. Eligible AYAO participants without a history of VTE were designated as controls and were randomly selected from our institution's tumor registry. Demographics, medical history, surgeries, central venous catheter (CVC) data, VTE diagnosis and treatment, relapses, and deaths were abstracted.

RESULTS

Thirty-five VTE cases and 70 controls were included in this analysis. Eighty percent of cases had leukemia or lymphoma (vs. a solid tumor) compared to 58% of controls. The majority of VTEs (57%) were CVC associated, and more than 70% of cases had more than one CVC placed during their cancer treatment versus 34% of controls. Infection was associated with increased VTE risk (OR = 6.35, 95% CI = 2.30, 17.55, p < .0001). VTE cases had increased cancer relapse (23% vs. 10%) and mortality rates (29% vs. 16%) than controls.

CONCLUSION

AYAO participants with a VTE were more likely to have leukemia or lymphoma, more than one CVC or infection. Further studies are needed to identify patients who would benefit from modifiable prevention measures, such as limiting to one CVC, preventing infections, or considering prophylactic anticoagulation for those with a liquid tumor.

Cerebral venous sinus thrombosis in a young child with acute lymphoblastic leukemia: a case report and literature review

Acute lymphoblastic leukemia (ALL) is a hematological malignancy. There are many risk factors for thrombus development in patients with ALL, and thrombi may develop in different parts of the body. Cerebral venous sinus thrombosis (CVST) is a rare complication of ALL that usually appears during treatment. We present a patient who developed CVST twice, once before diagnosis and once after treatment for ALL. We also reviewed the literature describing ALL and CVST.

Increased Toxicity Among Adolescents and Young Adults Compared with Children Hospitalized with Acute Lymphoblastic Leukemia at Children's Hospitals in the United States

Purpose: Adolescent and young adult (AYA) patients (15-39 years old) with acute lymphoblastic leukemia (ALL) have less favorable outcomes and higher treatment-related mortality as compared with older children with ALL. Minimal data exist regarding how well AYA patients tolerate the intensity of chemotherapy at doses and regimens designed for children, and the toxicities suffered by this population at children's hospitals have not been thoroughly characterized. Methods: Pediatric Health Information Systems database was queried to analyze health care outcomes in pediatric (ages 10-14) and AYA patients (ages 15-39) with ALL hospitalized between January 1999 and December 2014. We extracted relevant ICD-9 data for each patient related to grades 3 or 4 toxicities as outlined by the NCI. Results: A total of 5345 hospital admissions met inclusion criteria, representing 4046 unique patients. Of these admissions, 2195 (41.1%) were in the AYA age group, and the remainder were in the 10-14-year-old group. AYA patients had a significantly higher incidence of intensive care unit stay but no difference in median hospital stay nor mortality. AYA patients had increased toxicities in almost every organ system as compared with older children. Conclusions: In this large multicenter US database study, we found an overall increased number of toxicities among AYA patients with ALL in children's hospitals. Compared with children between the ages of 10 and 15, AYA patients developed disproportionately higher toxicities from drugs commonly used in pediatric protocols for ALL. Prospective studies are needed to assess whether dose modifications for certain chemotherapeutics may improve the toxicity profile and health care burden of AYA patients with ALL treated in children's hospitals.