Prospective study of thromboembolism in 1038 children with acute lymphoblastic leukemia: a Nordic Society of Pediatric Hematology and Oncology (NOPHO) study

Sequelae and post-thrombotic syndrome after venous thromboembolism in acute lymphoblastic leukemia survivors treated on the NOPHO ALL2008 protocol

The treatment of acute lymphoblastic leukemia (ALL) is frequently complicated by toxicity, including venous thromboembolism (VTE) affecting roughly 8% of patients. VTE can lead to post-thrombotic syndrome (PTS), a group of signs and symptoms developed as a complication to deep venous thrombosis (DVT), imposing risk of permanent disability and reduced quality of life (QoL). PTS prevalence ranges from 0% to 70%, reflecting very heterogenous cohorts and assessment tools. We aimed to estimate sequelae, including PTS and QoL in children and adults (<45 years old) who had a DVT during ALL treatment. PTS and QoL scores were obtained through use of Villalta and Modified Villalta Scale, PedsQL, and Short Form-36 questionnaires. The cohort comprised 20 children (<18 years) and seven adults (median age: 12.9 years, range: 2-44 years) at the time of DVT diagnosis. In total, 25 ALL survivors underwent PTS examination. The examination took place when survivors were 7-48 years (median age: 20.3 years, median follow-up time 6.8 years). QoL was assessed correlating cases with three matching ALL survivors without VTE. Two adults (15.4%) showed mild or moderate PTS. Eight children (66.7%) were diagnosed with mild PTS, while three cases had collaterals as sole symptoms. Pain or symptoms affecting daily life were reported by 16%. No difference in QoL was found (p = .9). This study underscores the need for comprehensive population-based investigations with validation of PTS instruments in ALL survivors.

Development and validation of thromboembolism diagnostic algorithms in children with cancer from real-world data

OBJECTIVE

To evaluate the accuracy of diagnostic algorithms developed using the International Classification of Diseases (ICD-9-CM and ICD-10-CA) diagnostic codes and physician billing codes for thromboembolism (TE) from health administrative data compared to chart review diagnoses of TE in children with cancer.

METHODS

Using data linkage between the Pediatric Oncology Group of Ontario Network Information System (Ontario pediatric cancer registry) and various administrative data housed at ICES, eight algorithms were developed including a single reference to one of the billing codes, multiple references with varying time intervals, and combinations of various billing codes during primary cancer therapy for the whole cohort and, for early (<04/2002) and later (≥04/2002, solely ICD-10 codes) periods. Reference standard was chart review data from prior studies (from 1990 to 2016) among children (≤19 years) with cancer and radiologically confirmed TE.

RESULTS

Records of 2056 patients diagnosed with cancer at two participating sites during study period were reviewed; 112 had radiologically confirmed TE. The algorithm with addition of anticoagulation utilization codes was the best performing algorithm (sensitivity = 0.76;specificity = 0.85). With use of ICD-10 only codes, sensitivity of the same algorithm improved to 0.84 with specificity of 0.80.

CONCLUSION

This study provides a valid approach for ascertaining pediatric TE using real-world data.

IMPACT

Research in pediatric thrombosis, especially cancer-related thrombosis, is limited mainly due to small-sized studies. Real-world data provide ready access to large and diverse populations. However, there are no validated algorithms for identifying thrombosis in real-world data for children. An algorithm based on combination of thrombosis and anticoagulation utilization codes had 76% sensitivity and 85% specificity to identify diagnosis of thrombosis in children in administrative data. This study provides a valid approach for ascertaining pediatric thrombosis using real-world data and offers a good avenue to advance pediatric thrombosis research.

Risk factors and clinical impact of thrombosis during induction chemotherapy for pediatric acute lymphoblastic leukemia: A report from CYP-C

Thromboembolism (TE) is associated with reduced survival in pediatric acute lymphoblastic leukemia (ALL). It has been hypothesized that TE might signal leukemic aggressiveness. The objective was to determine risk factors for TE during ALL induction (TEind ) therapy and whether TEind is associated with treatment refractoriness. This retrospective cohort study using the population-based Cancer in Young People Canada (CYP-C) registry included children <15 years of age diagnosed with ALL (2000-2019) and treated at one of 12 Canadian pediatric centers outside of Ontario. Univariate and multivariable logistic regression models were used to determine risk factors for TEind and whether TEind predicted induction failure and ALL treatment intensification. The impact of TEind on overall and event-free survival was estimated using Cox proportional hazard regression models. The study included 2589 children, of which 45 (1.7%) developed a TEind . Age (<1 year and ≥10 years vs. 1-<10 years), T-cell phenotype, high-risk ALL, and central nervous system involvement were all associated with TEind in univariate analysis. Age and T-cell phenotype remained independent predictors of TEind in multivariable analysis. Induction failure occurred in 53 patients (2.1%). TEind was not associated with induction failure (OR: not estimable) or treatment intensification (adjusted OR [95% CI]: 0.66 [0.26-1.69]). TEind was independently associated with overall survival (adjusted HR [95% CI]: 2.54 [1.20-5.03]) but not event-free survival (adjusted HR [95% CI] 1.86 [0.98-3.51]). In this population-based study of children treated with contemporary chemotherapy protocols, TEind was associated with age and T-cell phenotype and mortality but did not predict induction failure.

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.

A Review of Acute Lymphocytic Leukemia (ALL) in the Pediatric Population: Evaluating Current Trends and Changes in Guidelines in the Past Decade

Acute lymphocytic leukemia (ALL) is a commonly diagnosed cancer in children. Despite technological advancements to improve treatment and survival rates, there has been a steady increase in the incidence of ALL and treatment failures. This paper discusses the pathogenic interaction between genetic and environmental factors leading to childhood ALL. It evaluates the current treatment guidelines and notable obstacles leading to resistance, relapse, and treatment toxicities. The review evaluates a 10-year trend in the management guidelines of pediatric ALL through a systematic literature review of records from 2012 to 2023. Findings show that improvement in the five-year survival rates, notwithstanding rates of relapse and incurable diseases, is still high. Furthermore, several risk factors, including an interplay between genetic and environmental factors, are largely contributory to the outcome of ALL treatments and its overall incidence. Moreover, huge financial costs have remained a significant challenge in outcomes. There remains a need to provide individualized treatment plans, shared decision-making, and goals of care as parts of the management guidelines for the best possible outcomes. We expect that future advancements will increase overall survival rates and disease-free years.

Just DOAC: Use of direct-acting oral anticoagulants in pediatrics

PURPOSE

The aim of this article is to provide an overview of the current literature for direct-acting oral anticoagulant (DOAC) use in pediatric patients and summarize ongoing trials.

SUMMARY

In treatment of venous thromboembolism (VTE) in pediatric patients, evidence supports use of both dabigatran and rivaroxaban. Dabigatran has been shown to be noninferior to standard of care (SOC) in terms of efficacy, with similar bleeding rates. Similarly, treatment with rivaroxaban in children with acute VTE resulted in a low recurrence risk and reduced thrombotic burden, without increased risk of bleeding, compared to SOC. Treatment of pediatric cerebral venous thrombosis as well as central venous catheter-related VTE with rivaroxaban appeared to be both safe and efficacious and similar to that with SOC. Dabigatran also has a favorable safety profile for prevention of VTE, and rivaroxaban has a favorable safety profile for VTE prevention in children with congenital heart disease. Many studies with several different DOACs are ongoing to evaluate both safety and efficacy in unique patient populations, as well as VTE prevention.

CONCLUSION

The literature regarding pediatric VTE treatment and prophylaxis is growing, but the need for evidence-based pediatric guidelines remains. Additional long-term, postauthorization studies are warranted to further elucidate safety and efficacy in clinical scenarios excluded in clinical trials. Additional data on safety, efficacy, and dosing strategies for reversal agents are also necessary, especially as the use of DOACs becomes more common in the pediatric population.

Correlation between asparaginase enzyme activity levels and coagulation parameters during childhood acute lymphoblastic leukemia treatment

Thromboembolism is a serious toxicity in the treatment of acute lymphoblastic leukemia (ALL), but little is known about the correlation between asparaginase enzyme activity (ASA) levels and coagulation parameters. We included 65 non-high risk ALL patients, aged 1-17 years. Coagulation parameters and corresponding ASA levels were measured during asparaginase treatment. We found ASA to be negatively correlated with antithrombin and fibrinogen up to ASA levels of 250 IU/L, after which these parameters reached a plateau and did not decrease further with further increase of ASA. Patients with silent inactivation of asparaginase had normal coagulation parameters.

Venous Thromboembolic Events in Adolescent and Young Adult Patients with Acute Lymphoblastic Leukemia

Acute venous thromboembolisms (VTEs) are serious complications that occur during acute lymphoblastic leukemia (ALL) chemotherapy. The data elucidating risk factors for developing VTEs are limited in adolescent and young adult patients being treated per pediatric ALL protocols. In a cohort of 66 patients, 14 (21%) experienced VTEs. The majority of VTEs occurred during induction chemotherapy after the first dose of asparaginase, and in the upper extremities. Five-year relapse-free and overall survival were not impacted by VTEs. Contrary to VTEs in adults, hypoalbuminemia and increased body mass index were not associated with an elevated risk of VTE.

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.

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.

Markers of hypercoagulability in children with newly diagnosed acute lymphoblastic leukemia

BACKGROUND

Venous thromboembolism (VTE) is a known complication for children with acute lymphoblastic leukemia (ALL). The aim of this study was to identify laboratory biomarkers that predict which children with ALL are at risk for VTE during induction chemotherapy.

MATERIALS AND METHODS

Newly diagnosed ALL patients admitted to Children's Hospital Los Angeles with a central venous catheter (CVC) were eligible to participate. Participants' blood samples (complete blood count [CBC], quantitative D-dimer, prothrombin fragment 1.2 [PTF 1.2], and thrombin-antithrombin complexes [TAT]) were collected at day 0 (baseline/prior to induction), day 7 (±2 days), day 14 (±2 days), day 21 (±2 days), and day 28 (±2 days) of induction chemotherapy or until participants presented with a symptomatic VTE.

RESULTS

Seventy-five participants aged 1-21 years were enrolled and included in the final analysis. Twenty-six (35%) of the 75 participants were diagnosed with a CVC-associated VTE (22 asymptomatic and four symptomatic). There was a statistically significant difference between VTE and non-VTE participants for D-dimer (odds ratio [OR] 1.61, 95% confidence interval [CI]: 1.59-1.64), TAT (OR 1.34, 95% CI: 1.32-1.38), and PTF 1.2 (OR 1.31, 95% CI: 1.25-1.37) at all time points. Participants >10 years had a significantly higher risk of developing a VTE compared to participants <4 years (p = .007).

CONCLUSION

Older children with ALL as well as those with an elevated TAT, PTF 1.2, or D-dimer showed an increased risk of VTE, which may hold potential for predicting VTE in future studies.

ICU Admission in Children With Acute Lymphoblastic Leukemia in Sweden: Prevalence, Outcome, and Risk Factors

OBJECTIVES

Despite progress in the treatment of childhood acute lymphoblastic leukemia, severe complications are common, and the need of supportive care is high. We explored the cumulative prevalence, clinical risk factors, and outcomes of children with acute lymphoblastic leukemia, on first-line leukemia treatment in the ICUs in Sweden.

DESIGN

A nationwide prospective register and retrospective chart review study.

SETTING

Children with acute lymphoblastic leukemia were identified, and demographic and clinical data were obtained from the Swedish Childhood Cancer Registry. Data on intensive care were collected from the Swedish Intensive Care Registry. Data on patients with registered ICU admission in the Swedish Childhood Cancer Registry were supplemented through questionnaires to the pediatric oncology centers.

PATIENTS

All 637 children 0-17.9 years old with acute lymphoblastic leukemia diagnosed between June 2008 and December 2016 in Sweden were included.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Twenty-eight percent of the children (178/637) were admitted to an ICU at least once. The Swedish Intensive Care Registry data were available for 96% of admissions (241/252). An ICU admission was associated with poor overall survival (hazard ratio, 3.25; 95% CI, 1.97-5.36; p ≤ 0.0001). ICU admissions occurred often during early treatment; 48% (85/178) were admitted to the ICU before the end of the first month of acute lymphoblastic leukemia treatment (induction therapy). Children with T-cell acute lymphoblastic leukemia or CNS leukemia had a higher risk of being admitted to the ICU in multivariable analyses, both for early admissions before the end of induction therapy and for all admissions during the study period.

CONCLUSIONS

The need for intensive care in children with acute lymphoblastic leukemia, especially for children with T cell acute lymphoblastic leukemia and CNS leukemia, is high with most admissions occurring during early treatment.

Obesity as a predictor of treatment-related toxicity in children with acute lymphoblastic leukaemia

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 2·0-17·9 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, <17 kg/m² ; healthy weight, 17 to <25 kg/m² ; overweight, 25 to <30 kg/m² ; and obese, ≥30 kg/m² . Obese children had a higher incidence rate ratio (IRR) for severe toxic events {IRR: 1·55 [95% confidence interval (CI) 1·07-2·50]}, 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 2·87 (95% CI 1·00-8·21)] and anaphylactic reactions [IRR 7·95 (95% CI 2·15-29·37)] as well as higher risk for truncation of asparaginase [IRR 3·54 (95% CI 1·67-7·50)]. 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.

Asparaginase Enzyme Activity Levels and Toxicity in Childhood Acute Lymphoblastic Leukemia: a NOPHO ALL2008 study

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.

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.

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.

Thrombosis in hematological malignancies: mechanisms and implications

A B S T R A C T Thrombotic events are a major cause of morbidity and mortality in cancer. While the association of venous thromboembolic events with cancer is well documented, in recent years arterial events (i.e. acute myocardial infarction and ischemic strokes) have also emerged as relatively common complications among cancer patients. In hematological malignancies incorporating a heterogeneous group of diseases, the prediction of thrombosis occurrence and/or recurrence is challenging, due to unique disease characteristics. Furthermore, the treatment of thrombosis in these patients is often complicated because of disease- or therapy-related thrombocytopenia. In addition, patients with hematological cancers are poorly represented in randomized control clinical trials; hence, evidence-based guidelines are limited. This review will discuss the incidence of venous and arterial thrombotic events in common myeloid and lymphoproliferative diseases. Several new mechanisms contributing to cancer- associated thrombosis will be elaborated. The complicated issue of risk assessment and management of venous thrombosis in patients with hematological malignancies will be delineated.

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.

Up-regulated miR-155 is associated with poor prognosis in childhood acute lymphoblastic leukemia and promotes cell proliferation targeting ZNF238

OBJECTIVES

Acute lymphoblastic leukemia (ALL) is one of the most common malignancies in children. Our aim was to identify a novel miRNA that can predict prognosis of childhood ALL patients and explore its potential mechanism.

METHODS

The miRNA expression profiles of childhood ALL were analyzed using GEO database and HiSeq instruments. The expression of miR-155 was examined by RT-PCR in 42 ALL patients. To investigate the role of miR-155 in ALL, four ALL cell lines (CEM-C1, Jurkat, MOLT-3 and MOLT-4) were transfected with miR-155 mimics, miR-155 inhibitors or corresponding controls. Dual-luciferase reporter system was applied to confirm the miR-155 target ZNF238. Moreover, proliferation and apoptosis were evaluated by MTT and flow cytometry.

RESULTS

Dataset GSE56489 and GSE23024 demonstrated that miR-155 was up-regulated and ZNF238 was down-regulated at diagnosis status of ALL. High miR-155 expression was associated with poor outcome. Overexpressed miR-155 promoted ALL cell proliferation and inhibited apoptosis. Dual-luciferase reporter result showed that miR-155 directly regulated ZNF238. Silencing ZNF238 promoted cell proliferation in ALL cells.

DISCUSSION

Our research indicating that miR-155 might possess potential value as a biomarker for predicting the prognosis of individuals. However, the role of ZNF238 in childhood ALL remain unknown. In the present study, we found the possible role of ZNF238 as a new tumor suppressor in ALL, which might be necessary for the antiproliferative functions of normal cells to counteract ALL formation.

CONCLUSION

Our results propose that miR-155 is in association with poor prognosis of childhood ALL. Furthermore, miR-155 could promote cell proliferation targeting ZNF238.

Asymptomatic Right Atrial Thrombosis After Acute Lymphoblastic Leukemia Treatment

Right atrial thrombosis is a rare, but potentially serious complication of acute lymphoblastic leukemia treatment. We conducted a retrospective multicenter study to assess the incidence, treatment, and outcome of asymptomatic right atrial thrombosis detected at routine echocardiography of children after acute lymphoblastic leukemia treatment in the Nordic and Baltic countries. Eleven (2.7%, 95% confidence interval, 1.4-4.9) of 406 patients had asymptomatic right atrial thrombosis, ranging from 10 to 25 mm at detection. Three patients were treated with anticoagulation. None of the thromboses affected cardiac function, and they showed neither sign of progress nor spontaneous or treatment-related regress at follow-up.

Central venous catheters are an important factor in paediatric thrombosis

AIM

To establish the incidence and characteristics of paediatric thrombosis (PT) in a Canadian tertiary care centre during the era of low molecular weight heparin (LMWH).

METHODS

A retrospective observational case study of all patients <18 years of age evaluated for arterial and venous thrombosis from May 2008 to July 2018 at McMaster Children's Hospital was conducted through the electronic medical record.

RESULTS

The incidence of PT was 52.2 per 10 000 hospital admissions (n = 477/91 462). Provoked thrombosis was more prevalent (88.9%, n = 424/477) than unprovoked (2.9%, n = 14/477) or idiopathic thrombosis (4%, n = 19/477). Half of PT were in children <2 years (51.2%, n = 244/477). Central vascular catheterisation was a contributory factor in more than half of thrombotic events (56.2%, n = 268/477), while trauma (1.1%, n = 5/477), oral contraceptives (4%, n = 19/477), infection (4%, n = 19/477), surgery (6.9%, n = 33/477) and malignancy (8.4%, n = 40/477) were also risk factors. Arterial ischaemic stroke was diagnosed in 11.1% of cases (n = 53/477), while pulmonary embolism was identified in 7.1% (n = 34/477) and 1.7% of cases were fatal (n = 8/477). LMWH was the first-line therapeutic of choice (47.8%, n = 228/477), with 28.1% (n = 134/477) requiring no intervention.

CONCLUSION

These data reiterate the elevated thrombosis risk to which infants and children with central vascular access are exposed.

A pilot study of procoagulant platelet extracellular vesicles and P-selectin increase during induction treatment in acute lymphoblastic leukaemia paediatric patients: two new biomarkers of thrombogenic risk?

In paediatric acute lymphoblastic leukaemia (ALL), focus has shifted towards preventing treatment-related complications, including venous thromboembolism, the cause of significant mortality and morbidity. To better understand thrombogenic mechanisms during induction treatment, we studied the number, origin and procoagulant activity of extracellular vesicles (EVs) and P-selectin level throughout the induction course in 24 paediatric patients. EVs were mainly of platelet origin. We observed a significant increase in EV number, in platelet EV number and P-selectin level throughout the induction course. There was a correlation between higher EV and platelet EV number, P-selectin level, higher platelet count and leucocyte count. We also observed a correlation between higher EV procoagulant activity and higher platelet count and leucocyte count and higher P-selectin level. Older age and T phenotype were associated with a higher EV procoagulant activity. Platelet EV generation may play a role in thrombogenic complications in ALL patients and could serve as a biomarker to identify patients with a high risk of thrombosis. As a marker of platelet activation, P-selectin may be another relevant marker with the advantage of being easier to analyse in clinical practice.

Managing toxicities with asparaginase-based therapies in adult ALL: summary of an ESMO Open-Cancer Horizons roundtable discussion

With recent prospective clinical trials that used paediatric regimens with multiple doses of pegylated form of asparaginase (PEG asparaginase) in adults reporting significantly improved survival compared with historical data with regimens that used less asparaginase, PEG asparaginase is increasingly being used in the treatment of adult acute lymphoblastic leukaemia (ALL). However, administering asparaginase still comes with its challenges, especially in adult patients. Therefore, it is important to understand how to manage its toxicities properly. An expert group met in November 2019 in London to discuss recent data of paediatric as well as adult studies using paediatric regimens with regard to the best management of several key toxicities that can occur in adults treated with asparaginase including hepatotoxicity, pancreatitis, hypertriglyceridaemia, thrombosis and hypersensitivity. Several recommendations were made for each one of these toxicities, with the goal of safe administration of the drug and to educate clinicians when the drug can be continued despite side effects.

Pulmonary embolism in acute lymphoblastic leukemia - An observational study of 1685 patients treated according to the NOPHO ALL2008 protocol

BACKGROUND

Pulmonary embolism (PE) is a serious complication of acute lymphoblastic leukemia (ALL). We examined the cumulative incidence and clinical presentation of PE in a well-defined cohort of patients with ALL aged 1-45 years treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol.

METHODS

As part of the mandatory toxicity reporting of NOPHO ALL2008, thromboembolism including PE was reported consecutively. The cumulative incidence of first-time PE was calculated using the Aalen-Johansen estimator during a 2.5-year period from ALL diagnosis. We used Fisher's exact test to examine categorical variables and Cox logistic regression to estimate hazard ratios (HRs) for PE.

RESULTS

PE was diagnosed in 32 of 1685 patients. The 2.5-year cumulative incidence of first-time PE increased with age: 0.43% (95% CI, 0.18-1.03) in children aged 1-9 years, 3.28% (95% CI, 1.72-6.22) in children aged 10-17 years, and 7.22% (95% CI, 4.61-11.21) in adults aged 18-45 years. The majority of PEs, 78% (25/32), occurred during asparaginase treatment. HRs adjusted for age and sex were associated with male sex (HR, 2.4; 95% CI, 1.0-5.6) and older age (10-17 years: HR 7.5; 95% CI, 2.5-22.2), 18-45 years: HR, 16.5; 95% CI, 6.1-44.5). In two-thirds of the patients (63%; 17/27), PE and its treatment had no impact on the administered doses of asparaginase. PE-associated 30-day mortality was 9.4% (95% CI, 1.9-25.0).

CONCLUSIONS

Awareness of PE is warranted during ALL treatment. Larger multicenter studies are needed to examine predictors of PE in ALL.

Genome-Wide Association Meta-Analysis of Single-Nucleotide Polymorphisms and Symptomatic Venous Thromboembolism during Therapy for Acute Lymphoblastic Leukemia and Lymphoma in Caucasian Children

Symptomatic venous thromboembolism (VTE) occurs in five percent of children treated for acute lymphoblastic leukemia (ALL), but whether a genetic predisposition exists across different ALL treatment regimens has not been well studied.

METHODS

We undertook a genome-wide association study (GWAS) meta-analysis for VTE in consecutively treated children in the Nordic/Baltic acute lymphoblastic leukemia 2008 (ALL2008) cohort and the Australian Evaluation of Risk of ALL Treatment-Related Side-Effects (ERASE) cohort. A total of 92 cases and 1481 controls of European ancestry were included.

RESULTS

No SNPs reached genome-wide significance (p < 5 × 10-8) in either cohort. Among the top 34 single-nucleotide polymorphisms (SNPs) (p < 1 × 10-6), two loci had concordant effects in both cohorts: ALOX15B (rs1804772) (MAF: 1%; p = 3.95 × 10-7) that influences arachidonic acid metabolism and thus platelet aggregation, and KALRN (rs570684) (MAF: 1%; p = 4.34 × 10-7) that has been previously associated with risk of ischemic stroke, atherosclerosis, and early-onset coronary artery disease.

CONCLUSION

This represents the largest GWAS meta-analysis conducted to date associating SNPs to VTE in children and adolescents treated on childhood ALL protocols. Validation of these findings is needed and may then lead to patient stratification for VTE preventive interventions. As VTE hemostasis involves multiple pathways, a more powerful GWAS is needed to detect combination of variants associated with VTE.

Dyslipidemia at diagnosis of childhood acute lymphoblastic leukemia

As survival of acute lymphoblastic leukemia (ALL) exceeds 90%, limiting therapy-related toxicity has become a key challenge. Cardio-metabolic dysfunction is a challenge during and after childhood ALL therapy. In a single center study, we measured triglycerides (TG), total cholesterol (TC), high (HDL) and low density lipoproteins (LDL) levels at diagnosis and assessed the association with BMI, early therapy response, on-therapy hyperlipidemia and the toxicities; thromboembolism, osteonecrosis and pancreatitis. We included 127 children (1.0-17.9 years) all treated according to the NOPHO ALL2008 protocol. Dyslipidemia was identified at ALL-diagnosis in 99% of the patients, dominated by reduced HDL levels (98%) and mild hypertriglyceridemia (61%). Hypertriglyceridemia was not associated with body mass index (P = 0.71). Five percent of patients had mild hypercholesterolemia, 14% had mild hypocholesterolemia, 13% had decreased and 1% elevated LDL-levels. Increased TG and TC levels at ALL-diagnosis were not associated with any on-therapy lipid levels. Lipid levels and BMI were not associated to MRD after induction therapy; However, BMI and hypercholesterolemia were associated with worse risk group stratification (P<0.045 for all). The cumulative incidence of thromboembolism was increased both for patients with hypo- (20.0%) and hypercholesterolemia (16.7%) compared to patients with normal TC levels (2.2%) at diagnosis (P = 0.0074). In conclusion, dyslipidemic changes were present prior to ALL-therapy in children with ALL but did not seem to affect dysmetabolic traits during therapy and were not predictive of on-therapy toxicities apart from an association between dyscholesterolemia at time of ALL-diagnosis and risk of thromboembolism. However, the latter should be interpreted with caution due to low number in the groups.

Vincristine induces procoagulant activity of the human lymphoblastic leukemia cell line Jurkat through the release of extracellular vesicles

Thromboembolic events are frequent and serious complications of acute lymphoblastic leukaemia treatment. The importance of chemotherapy in the pathogenesis of this increased risk is enhanced by the fact that thrombosis rarely occurs at diagnosis. Our study aims at investigating the effect of chemotherapy on pro-coagulant activity (PCA), phosphatidylserine (PS) exposure, tissue factor (TF) activity and derived extracellular vesicles (EV) of Jurkat cells. Jurkat cells were treated with two commonly used chemotherapeutics: Vincristine (VCR) or Daunorubicin (DNR), at relevant concentrations. PCA of cells and derived EV were evaluated using Thrombin generation Assay (TGA). Cells or EV were incubated with annexin V or anti TF antibodies to assess the respective contribution of TF and PS. PS exposure on cells was analysed by flow cytometry. Derived EV were evaluated in fluorescence microscopy and flow cytometry. Untreated Jurkat cells and EV support thrombin generation. Thrombin generation was abolished when PS activity was inhibited by annexin V. VCR treatment resulted in a time dependent increase of thrombin generation. After VCR exposure, TF activity increased as well as PS exposure increased on the cell surface. The increase in TF activity was abolished by annexin V indicating that PS was required. A spontaneous release of EV from Jurkat cells was observed and VCR treatment increased the number of generated EV. Our results indicate that VCR increased the PCA of Jurkat cells predominantly through PS exposure and increased EV generation. Lymphoid blasts derived EV could be biomarkers to determine high thrombotic risk ALL patients.

Medication errors in a cohort of pediatric patients with acute lymphoblastic leukemia on remission induction therapy in a tertiary care hospital in Mexico

INTRODUCTION

Medication errors (MEs) are the main type of preventable adverse events in medical care, as well as safety indicators in the medication processes. Advances in the quality of care in pediatric acute lymphoblastic leukemia (ALL) have enabled to improve clinical outcomes. However, ME epidemiology in pediatric oncology is still incipient in developing countries. In view of this, the objectives of this study were to estimate the incidence of MEs, determine their types and consequences, as well as their preventability in the induction treatment of children with ALL at Hospital Infantil de Mexico Federico Gómez.

METHODS

We reviewed the remission-induction chemotherapy records of children with ALL between January 2015 and December 2017. A two-phase review was carried out for ME identification and verification. The consequences of errors were determined by agreement between reviewers.

RESULTS

We reviewed 1762 chemotherapy orders involving 181 children. MEs were observed in 16.9% of orders and in 57.5% of patients. Prescription errors were the most common (93.3%), with wrong dose errors (90.2%) being predominant. Only 3.7% of wrong dose errors were intercepted, while 12.2% of the children experienced adverse drug events (ADEs) preceded by some wrong dose error.

CONCLUSIONS

MEs were common, since they occurred in 57.5% of children with ALL on induction treatment and involved 16.5% of chemotherapy orders. Only 3.7% of MEs were intercepted, while 12.2% of children had ADEs related to overdose. Measures are required to prevent calculation error in prescriptions, as well as training of the nursing staff to intercept MEs.

Intermittent Versus Continuous PEG-Asparaginase to Reduce Asparaginase-Associated Toxicities: A NOPHO ALL2008 Randomized Study

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.

Symptomatic Cerebral Sinovenous Thrombosis Associated With L-Asparaginase In Children With Acute Lymphoblastic Leukemia: A Single Institution Experience Over 17 Years

BACKGROUND

Cerebral sinovenous thrombosis (CSVT) is a rare, yet important complication of acute lymphoblastic leukemia (ALL) therapy, associated with significant morbidity and mortality. Paucity of data from India prompted us to report our experience with CSVT over a period of 17 years.

MATERIALS AND METHODS

This is a retrospective analysis of 500 consecutive ALL patients, below 18 year of age, treated between January 1998 and December 2014, who developed symptomatic CVST.

RESULTS

Seven of the 467 eligible patients developed symptomatic CVST with an incidence of 1.5% (7/467). Six of the CVST events, occurred during induction and 1 during reinduction. Median time to symptoms was 21 days (range, 2 to 27 d) from first exposure to L-asparaginase therapy. Management included low-molecular-weight heparin (enoxaparin sodium) at a dose of 1 mg/kg twice a day for at least 3 months along with supportive care. There were 2 thrombosis-attributable deaths. The remaining patients tolerated rechallenge with L-asparaginase uneventfully during reinduction, under cover of heparin prophylaxis. Complete neurological recovery was observed in all surviving patients.

CONCLUSIONS

Incidence of symptomatic L-asparaginase associated CSVT during ALL treatment was 1.5% with high case fatality rate (28%). It is noteworthy that full neurological recovery is likely in surviving patients, and rechallenge with L-asparaginase is safe with heparin prophylaxis. Currently available screening methods are not practically implementable in resource-limited settings.

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

Thromboembolism is a serious complication of induction therapy for childhood acute lymphoblastic leukemia. We prospectively compared the efficacy and safety of antithrombotic interventions in the consecutive leukemia trials ALL-BFM 2000 and AIEOP-BFM ALL 2009. Patients with newly diagnosed acute lymphoblastic leukemia (n=949, age 1 to 18 years) were randomized to receive low-dose unfractionated heparin, prophylactic low molecular weight heparin (enoxaparin) or activity-adapted antithrombin throughout induction therapy. The primary objective of the study was to determine whether enoxaparin or antithrombin reduces the incidence of thromboembolism as compared to unfractionated heparin. The principal safety outcome was hemorrhage; leukemia outcome was a secondary endpoint. Thromboembolism occurred in 42 patients (4.4%). Patients assigned to unfractionated heparin had a higher risk of thromboembolism (8.0%) compared with those randomized to enoxaparin (3.5%; P=0.011) or antithrombin (1.9%; P<0.001). The proportion of patients who refused antithrombotic treatment as allocated was 3% in the unfractionated heparin or antithrombin arms, and 33% in the enoxaparin arm. Major hemorrhage occurred in eight patients (no differences between the groups). The 5-year event-free survival was 80.9±2.2% among patients assigned to antithrombin compared to 85.9±2.0% in the unfractionated heparin group (P=0.06), and 86.2±2.0% in the enoxaparin group (P=0.10). In conclusion, prophylactic use of antithrombin or enoxaparin significantly reduced thromboembolism. Despite the considerable number of patients rejecting the assigned treatment with subcutaneous injections, the result remains unambiguous. Thromboprophylaxis - for the present time primarily with enoxaparin - can be recommended for children and adolescents with acute lymphoblastic leukemia during induction therapy. Whether and how antithrombin may affect leukemia outcome remains to be determined.

Thromboembolism in acute lymphoblastic leukemia: results of NOPHO ALL2008 protocol treatment in patients aged 1 to 45 years

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 (RR_age, 4.7 [95% CI, 3.1-7.1]; RR_{enlarged lymph nodes}, 2.0 [95% CI, 1.2-3.1]; RR_{mediastinal 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.

Non-infectious chemotherapy-associated acute toxicities during childhood acute lymphoblastic leukemia therapy

During chemotherapy for childhood acute lymphoblastic leukemia, all organs can be affected by severe acute side effects, the most common being opportunistic infections, mucositis, central or peripheral neuropathy (or both), bone toxicities (including osteonecrosis), thromboembolism, sinusoidal obstruction syndrome, endocrinopathies (especially steroid-induced adrenal insufficiency and hyperglycemia), high-dose methotrexate-induced nephrotoxicity, asparaginase-associated hypersensitivity, pancreatitis, and hyperlipidemia. Few of the non-infectious acute toxicities are associated with clinically useful risk factors, and across study groups there has been wide diversity in toxicity definitions, capture strategies, and reporting, thus hampering meaningful comparisons of toxicity incidences for different leukemia protocols. Since treatment of acute lymphoblastic leukemia now yields 5-year overall survival rates above 90%, there is a need for strategies for assessing the burden of toxicities in the overall evaluation of anti-leukemic therapy programs.

Venous thrombosis in children and adolescents with Hodgkin lymphoma in Sweden

INTRODUCTION

Pediatric patients with Hodgkin lymphoma (HL) have several risk factors for venous thromboembolism (VTE). Although these patients are occasionally treated with thromboprophylaxis, no guidelines are implemented in Sweden. Scarce data from adult patients indicate an increased risk of VTE, but pediatric data is largely missing. Given the favorable overall survival of HL, there should reasonably be more focus on preventing complications.

MATERIALS AND METHODS

We conducted a retrospective cohort study, including all patients registered in the Childhood Cancer Registry under the age of 18years diagnosed with HL between January 2005 and December 2015 in Sweden.

RESULTS

Data was retrieved from the medical records of all 163 patients (100%) at six Swedish pediatric cancer centers. The incidence of VTE was 7.7% (symptomatic VTE 3.9%). The median follow-up was 3.4years (range 0.3-10.5). Only five patients (3.1%) were treated with thromboprophylaxis. All VTE events occurred in the older age category (11-17years) and all but one (92.7%) had a mediastinal mass. While the VTE did not significantly affect the treatment of HL, it caused increased morbidity and 2/12 developed a post-thrombotic syndrome. No significant risk factors for VTE were identified.

CONCLUSIONS

VTE is a relatively common complication of HL and its treatment, causing increased acute and long-term morbidity. However, due to limited number of events we could not demonstrate risk-factors for VTE that would identify patients who might benefit from thromboprophylaxis.

Different profile of thrombin generation in children with acute lymphoblastic leukaemia treated with native or pegylated asparaginase: A cohort study

BACKGROUND

Asparaginase (Asp) and corticosteroid (CS) treatment in patients with acute lymphoblastic leukaemia (ALL) is associated with an increased risk of thrombotic events.

OBJECTIVE

Characterization of global haemostatic phenotypes of patients with ALL during Asp therapy.

PROCEDURE

Thrombin generation (TG) was monitored in platelet-poor plasma of 56 children treated for a B lineage ALL (36 with native, 20 with PEG Asp) using 1 pM tissue factor and 4 μM phospholipids, with and without thrombomodulin. Protein C activity (PC), free protein S (PS), antithrombin (AT) and fibrinogen levels were also measured.

RESULTS

Elevated endogenous thrombin potential (ETP) and peak of TG were noted at diagnosis, throughout the Induction phase and Late Intensification but was significantly less for PEG than for native Asp (P < 0.001), while age, sex, type of corticosteroid during Induction and molecular response had no significant effect. The reduction of ETP after addition of thrombomodulin was significantly lower in ALL children compared with that in controls, suggesting impairment in PS/PC pathway. Three patients experienced thrombosis: two treated with native and one with PEG Asp. The two patients with native Asp had, at the time of thrombosis, a prothrombotic profile.

CONCLUSIONS

Treatment with Asp, in combination with CS, enhances TG in children with ALL, more significantly with native than PEG Asp, which is present early at diagnosis, persists during Induction and reappears during Late Intensification. This is consistent with the high incidence of thrombotic events described during these phases of therapy. The less pronounced effect of PEG Asp remains to be elucidated.