Thrombosis in childhood acute lymphoblastic leukaemia: epidemiology, aetiology, diagnosis, prevention and treatment

Thrombin Generation Profile Using ST-Genesia after PEG-asparaginase in Pediatric Patients with Acute Lymphoblastic Leukemia

BACKGROUND

 Venous thromboembolism (VTE) etiology in children with acute lymphoblastic leukemia (ALL) is multifactorial. The use of global assays of hemostasis as a thrombin generation test (TGT) is useful to individualize VTE risk in adult patients. This prospective cohort study aimed to evaluate the usefulness of an automated TGT to evaluate VTE risk during ALL treatment in children.

METHODS

 TGT (automated analyzer ST Genesia; ThromboScreen) and pro- and anticoagulant plasma proteins were analyzed during ALL treatment in pediatric patients following LAL-SEHOP-PETHEMA-2013 guidelines. Results were compared with a series of pediatric normal controls and evaluated according to pegylated asparaginase PEG-ASP administration and to VTE risk factors.

RESULTS

 The study included 67 patients: males n = 35, B-ALL (n = 60). None had a VTE during the evaluated period. Compared to healthy controls, the normalized endogenous thrombin potential (N-ETP) ratio in patients was higher and ETP inhibition (ETP-inh) was lower, especially after PEG-ASP administration. Plasmatic protein C and protein S levels decreased after PEG-ASP administration, but antithrombin mean level did not. A bivariant analysis showed that ETP-inh was lower in patients >10 years old (p = 0.05) and in those with non-O blood type (p = 0.005). A linear mixed model also showed a higher TGT prothrombotic profile in patients with inherited thrombophilia.

CONCLUSION

 TGT could be a biomarker of a high VTE risk in ALL pediatric patients. Non-O blood group and inherited thrombophilia were associated with a significantly higher thrombotic profile, and an increased profile was also observed after administration of PEG-ASP.

Platelet-derived microparticles and their cargos: The past, present and future

All eukaryotic cells can secrete extracellular vesicles, which have a double-membrane structure and are important players in the intercellular communication involved in a variety of important biological processes. Platelets form platelet-derived microparticles (PMPs) in response to activation, injury, or apoptosis. This review introduces the origin, pathway, and biological functions of PMPs and their importance in physiological and pathological processes. In addition, we review the potential applications of PMPs in cancer, vascular homeostasis, thrombosis, inflammation, neural regeneration, biomarkers, and drug carriers to achieve targeted drug delivery. In addition, we comprehensively report on the origin, biological functions, and applications of PMPs. The clinical transformation, high heterogeneity, future development direction, and limitations of the current research on PMPs are also discussed in depth. Evidence has revealed that PMPs play an important role in cell-cell communication, providing clues for the development of PMPs as carriers for relevant cell-targeted drugs. The development history and prospects of PMPs and their cargos are explored in this guidebook.

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.

Incidence and Management of Thromboembolism in Patients with Acute Leukemia

Thromboembolic events (TE) in childhood are relatively rare but, serious complications of acute leukemia. The aim was to define the incidence and risk factors of thrombosis in children with leukemias. The electronic files of pediatric denovo/relapsed acute leukemia patients aged below 18 years, treated between 2011 and 2021 were retrospectively evaluated for thrombotic attacks. Thirty out of 469 patients developed 35 thrombotic events. The median age at the time of the TE was 11.8 (2-17.6) years, and the median time from diagnosis to TE was 9 (0-58) months. The frequency of TE was found at 7.4% (n = 35/469). When catheter related (n = 13) events, superficial venous events (n = 10), and arterial central nervous system thrombosis (n = 1) were excluded, the frequency of TE was decreased to 2.3% (n = 11/469). Children older than 10 years old (13.8%; n = 21/152) had significantly higher thromboembolic events than the others (4.4%; n = 14/317) (p = 0.03). The majority of attacks were symptomatic 66% (n = 23/35). The most common complaints were local pain, swelling, and redness 52% (n = 12/23). The majority of attacks in patients with relapsed (75%; 6/8) and newly diagnosed acute lymphoblastic leukemia (40%; 10/25%) developed during the induction phase. Thrombosis recurred in 13.3% (n = 4/30) of cases more than once. Thrombotic attacks were successfully treated with low molecular weight heparin 60% (n = 21/35), and recombinant tissue plasminogen activator 17% (n = 6/35). None of the children were lost due to thrombosis. Thrombosis is an important complication during acute leukemia treatment. Successful results are obtained with early diagnosis and treatment attempts by creating awareness.

Venous thromboembolism in children with acute lymphoblastic leukemia in China: a report from the Chinese Children's Cancer Group-ALL-2015

Venous thromboembolism (VTE) is a complication in children with acute lymphoblastic leukemia (ALL). The Chinese Children's Cancer Group-ALL-2015 protocol was carried out in China, and epidemiology, clinical characteristics, and risk factors associated with VTE were analyzed. We collected data on VTE in a multi-institutional clinical study of 7640 patients with ALL diagnosed in 20 hospitals from January 2015 to December 2019. First, VTE occurred in 159 (2.08%) patients, including 90 (56.6%) during induction therapy and 108 (67.92%) in the upper extremities. T-ALL had a 1.74-fold increased risk of VTE (95% CI 1.08-2.8, P = 0.022). Septicemia, as an adverse event of ALL treatment, can significantly promote the occurrence of VTE (P < 0.001). Catheter-related thrombosis (CRT) accounted for 75.47% (n = 120); and, symptomatic VTE, 58.49% (n = 93), which was more common in patients aged 12-18 years (P = 0.023), non-CRT patients (P < 0.001), or patients with cerebral thrombosis (P < 0.001). Of the patients with VTE treated with anticoagulation therapy (n = 147), 4.08% (n = 6) had bleeding. The VTE recurrence rate was 5.03% (n = 8). Patients with VTE treated by non-ultrasound-guided venous cannulation (P = 0.02), with residual thrombus (P = 0.006), or with short anticoagulation period (P = 0.026) had high recurrence rates. Thus, preventing repeated venous puncture and appropriately prolonged anticoagulation time can reduce the risk of VTE recurrence.

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.

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.

[Clinical characteristics and prognosis of seizures in 75 children with acute lymphoblastic leukemia]

OBJECTIVE

To investigate the clinical characteristics, treatment, and prognosis of seizures in children with acute lymphoblastic leukemia (ALL) during chemotherapy.

METHODS

Children with ALL with seizures during chemotherapy admitted to the Department of Pediatrics, Peking University People's Hospital from January 2010 to March 2022 were retrospectively analyzed. Clinical data including the incidence of seizure, time at seizure onset, causes, management, and prognosis were collected retrospectively.

RESULTS

A total of 932 children with ALL were admitted during the study period, of whom, 75 (8%) were complicated with seizures during the period of chemotherapy. There were 40 males and 35 females, with a median age of 7.5 (1-17) years, and 43 cases (57.3%) occurred within the first 2 months of chemotherapy. The underlying diseases were reversible posterior encephalopathy syndrome (n=15), cerebral hemorrhage (n=10, one of whom was complicated with venous sinus thrombosis), intrathecal or systemic methotrexate administration (n=11), brain abscess (n=7, fungal infection in 3 cases, and bacterial in 4), viral encephalitis (n=2), febrile seizure (n=7), hyponatremia (n=7), hypocalcemia (n=2), and unknown cause (n=14). Sixty-four children underwent neuroimaging examination after seizure occurrence, of whom 37 (57.8%) were abnormal. The electroencephalograhpy (EEG) was performed in 44 cases and was abnormal in 24 (54.4%). Fifty-five patients remained in long-term remission with regular chemotherapy, 8 patients received hematopoietic stem cell transplantation, 9 died and 3 lost to follow-up. Symptomatic epilepsy was diagnosed in 18 cases (24%), and was well controlled in 16 with over 1 year of seizure-free. Whereas 2 cases were refractory to anti-seizure medications.

CONCLUSION

Seizures are relatively common in children with ALL, most commonly due to reversible posterior encephalopathy syndrome, methotrexate-related neurotoxicity, and cerebral hemorrhage. Seizures occurred within 2 months of chemotherapy in most cases. Neuroimaging and EEG should be performed as soon as possible after the first seizure onset to identify the etiology and to improve the treatment regimen. Some cases developed symptomatic epilepsy, with a satisfactory outcome of seizure remission mostly after concurrent antiseizure medication therapy.

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.

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.

Primary thromboprophylaxis to prevent thrombotic events in pediatric oncology patients with a malignant mediastinal mass

Children with malignant mediastinal masses have increased thrombotic events (TE). Eligible subjects with malignant mediastinal masses between January 2000 and December 2017 were evaluated for TE, with 19 among 76 subjects receiving enoxaparin thromboprophylaxis. There were 13 TEs among 76 subjects for an incidence of 17.1%. Mediastinal compression directly led to TE in 9.2% of subjects who also had statistically significant superior vena cava compression at diagnosis. Primary thromboprophylaxis did not significantly affect TE occurrence; however, larger studies are warranted to consider strategic thromboprophylaxis guided by radiological monitoring of dynamic vascular compression to improve TE outcomes.

Clinical Utility of Pegaspargase in Children, Adolescents and Young Adult Patients with Acute Lymphoblastic Leukemia: A Review

Acute lymphoblastic leukemia (ALL) is a heterogenous hematological malignancy representing 25% of all cancers in children less than 15 years of age. Significant improvements in survival and cure rates have been made over the past four decades in pediatric ALL treatment. Asparaginases, derived from Escherichia coli and Erwinia chrysanthemi, have become a critical component of ALL therapy since the 1960s. Asparaginases cause depletion of serum asparagine, leading to deprivation of this critical amino acid for protein synthesis, and hence limit survival of lymphoblasts. Pegaspargase, a conjugate of monomethoxypolyethylene glycol (mPEG) and L-asparaginase, has become an integral component of pediatric upfront and relapsed ALL protocols due to its longer half-life and improved immunogenicity profile compared to native asparaginase preparations. Over the past two decades great strides have been made in outcomes for pediatric ALL due to risk stratification, incorporation of multiagent chemotherapy protocols, and central nervous system prophylaxis with pegaspargase having played an important role in this success. However, adolescents and young adults (AYA) with ALL when treated on contemporaneous trials using adult ALL regimens, continue to have poor outcomes. There is increasing realization of adapting pediatric trial regimens for treating AYAs, especially those incorporating higher intensity of chemotherapeutic agents with pegaspargase being one such agent. Dose or treatment-limiting toxicity is observed in 25-30% of patients, most notable being hypersensitivity reactions. Other toxicities include asparaginase-associated pancreatitis, thrombosis, liver dysfunction, osteonecrosis, and dyslipidemia. Discontinuation or subtherapeutic levels of asparaginase are associated with inferior disease-free survival leading to higher risk of relapse, and in cases of relapse, a higher risk for remission failure. This article provides an overview of available evidence for use of pegaspargase in pediatric acute lymphoblastic leukemia.

Incidence and risk factors of venous thrombotic events in pediatric patients with CNS tumors compared with non-CNS cancer: A population-based cohort study

BACKGROUND

Venous thromboembolism (VTE) is a well-recognized complication in pediatric cancer patients. It has been demonstrated that the incidence of VTE in pediatric patients with central nervous system (CNS) tumors is lower than that of patients with other cancers. Risk factors for developing cancer-related thrombosis are numerous and can include patient, disease, or treatment-related influences. The present study was designed to assess the VTE incidence in a pediatric oncology population, and to investigate whether intensity of treatment has similar associated with risk of VTE development in patients with and without CNS tumors.

METHODS

A retrospective population-based cohort study of pediatric oncology patients in Atlantic Canada was conducted. Data collected from medical records included demographics, cancer type, treatment, presence of central venous catheters (CVC), and presence of thrombosis. Treatment intensity was assessed using the intensity of treatment rating scale (ITR-3). Study period was from January 2000 to December 2017. SPSS version 24 was used for statistical analysis.

RESULTS

Of 1262 patients with pediatric cancer, 247 (19.6%) had CNS tumors. VTE occurred in significantly fewer (n = 5, 2%) patients with CNS tumors compared with patients with non-CNS cancers (n = 79, 7.8%) (p = 0.001). The ITR-3 scores did not differ significantly between the CNS and non-CNS groups (p = 0.638). In a multivariate logistic regression analysis, ITR-3 score was associated with VTE (odds ratio [OR]: 1.48, 95% CI: 1.2-1.9), while presence of CNS tumor was protective (OR: 0.26, 95% CI: 0.1-0.6).

CONCLUSIONS

We demonstrate that pediatric patients with CNS tumors experience a significantly lower incidence of VTE compared with patients with non-CNS cancer. An increase in the ITR-3 rating significantly increased the odds of developing VTE.

Cancer-associated thrombosis in pediatric patients

Childhood malignancy and especially acute lymphoblastic leukemia are increasingly associated with thromboembolism. The etiology of pediatric cancer associated thrombosis is multifactorial and may reflect a tumor mass effect, tumor thrombi, alterations of the hemostatic system, treatment-related hazards (e.g. procoagulant changes induced by chemotherapy), presence of central venous lines and comorbidities (e.g. inherited thrombophilia). With over 80% cure rates of childhood cancer, strategies for prevention as well as for early diagnosis and optimal treatment of thromboembolism in children with malignancies are of major importance. While the use of therapeutic low molecular weight heparin prevails, prospective studies regarding guidelines for treatment or prevention are currently lacking. This review will address the epidemiology, etiology and risk factors for thrombosis, describe the presently available evidence associated with current therapy, and offer a glimpse into future treatment options.

Cerebral Sinus Venous Thrombosis in Indian Pediatric Patients With Acute Lymphoblastic Leukemia: Incidence, Risk Factors, and Outcome

Cerebral sinus venous Thrombosis (CSVT) is a rare complication of acute lymphoblastic leukemia (ALL) treatment, with an incidence rate ranging from 1.1% to 2.9%. Steroids and L-asparaginase (LASP) are the major risk factors.

The aim of this study was to find the incidence rate and risk factors for CSVT in our patients. Ninety-two pediatric ALL diagnosed and treated with ALL-Berlin–Frankfurt–Munster-95 protocol over a period of 5 years (2013–2017) were the subject of the study. Six (6.5%) patients developed CSVT during their therapy and were further analyzed.

Six (five males and one female) patients had a CSVT event. The mean age at presentation was 13.5 ± 4.1 years. CSVT event occurred during the induction/re-induction phase of chemotherapy. The superior sagittal sinus was the most frequent site of thrombosis. The timing of CSVT was related to using of LASP and steroids. High-risk disease was associated with an increased risk of thrombosis. Infection and dehydration were other important risk factors. No association was observed between the risk of CSVT and age, sex, immunophenotype, and white blood cell count. All the patients were treated with low-molecular-weight heparin and one patient developed heparin-induced thrombocytopenia. No death occurred due to CSVT.

The Incidence of CSVT was 6.5% in our study which is significantly high but comparable with studies from other Asian countries. It is, therefore, important to be vigilant for the detection of CSVT during treatment of ALL and initiate the appropriate treatment to prevent adverse events.

Analysis of apoptotic, platelet-derived, endothelial-derived, and tissue factor-positive microparticles of children with acute lymphoblastic leukemia during induction therapy

OBJECTIVES

Thromboembolism is one of the most common complications during induction therapy of pediatric acute lymphoblastic leukemia (ALL). Procoagulant microparticles in the circulation may cause thromboembolic events. The aim of our study was to determine the levels of apoptotic, platelet-derived, endothelial-derived, and tissue factor-positive microparticles of children with ALL at diagnosis and during induction therapy.

METHODS

Sixteen precursor B-cell ALL cases and 30 healthy children between 1 and 18 years of age were included. Microparticle levels were analyzed from peripheral blood samples at initial diagnosis, on days 12 and 13 (before and after the first L-asparaginase administration), and on day 33 of ALL-BFM 2000 treatment protocol. Microparticle levels were analyzed by using flow cytometry.

RESULTS

At initial diagnosis, platelet, endothelial-derived, and tissue factor-positive microparticle levels were significantly high in children with ALL. They increased significantly after prednisone and L-asparaginase administration. Apoptotic microparticle levels were not elevated at diagnosis, but remained high during all induction therapy period. None of the patients had evidence of thromboembolism during induction therapy.

CONCLUSION

Our study demonstrated that children with ALL have increased levels of apoptotic, platelet-derived, endothelial-derived, and tissue factor-positive microprticles during induction therapy. Further studies are needed in larger groups of patients in order to evaluate the risk of elevated microprticles for development of thromboembolism during induction therapy period in children with ALL.

Antithrombin and fibrinogen levels as predictors for plasma L-asparaginase activity in children with acute lymphoblastic leukemia

BACKGROUND

L-asparaginase is a cornerstone treatment for children with acute lymphoblastic leukemia (ALL). However, immune reaction to the drug may increase the clearance or impair the function of L-asparaginase and reduces its therapeutic efficacy. The objective of this study was to identify potential plasma proteins that could be used as proxies for L-asparaginase activity.

METHODS

Fibrinogen, von Willebrand factor antigen (VWF:Ag), total protein, and albumin levels as well as antithrombin (AT) and L-asparaginase activities were measured in 97 children with ALL treated for prolonged period of time with L-asparaginase. Binary logistic regression and a receiver operating characteristic (ROC) curve analysis were performed to evaluate the predictive value of plasma proteins for L-asparaginase activity.

RESULTS

Median E. coli L-asparaginase activity was 220 IU/L (range, 0-1308) throughout the treatment period. L-asparaginase activity was below 100 IU/L in 23% of measured samples. L-asparaginase activity was inversely associated with AT activity, fibrinogen, total protein, and albumin levels (r = -0.63, -0.62, -0.57, and -0.45, respectively; P < 0.0001), but not with VWF:Ag. ROC curve analyses showed an intermediate accuracy of AT activity (area under the ROC curve [AUC] = 0.77) to detect specimens with subtherapeutic level of L-asparaginase. An optimal accuracy was found when AT and fibrinogen were combined (AUC = 0.82; sensitivity = 75%; specificity = 82%; positive predictive value = 55%; negative predictive value = 92%) with cutoff values of 0.73 IU/mL and 1.85 g/L, respectively.

CONCLUSIONS

AT combined with fibrinogen levels could be used as a proxy to identify patients with therapeutic level of L-asparaginase activity in the absence of real-time asparaginase measurement during prolonged exposure to L-asparaginase.

Venous thromboembolism in a large cohort of children with acute lymphoblastic leukemia: Risk factors and effect on prognosis

BACKGROUND

Venous thromboembolism (VTE) is relatively common in children with acute lymphoblastic leukemia (ALL). Thrombotic risk factors in ALL are asparaginase and steroids. However, within the ALL populations treated on the same regimen, it is less clear which other risk factors play a role. Furthermore, few data are available on the effect of VTE on ALL outcomes.

METHODS

In 778 children (1-18 years) with newly diagnosed precursor-B-lineage or T-lineage ALL, treated in the Dutch Childhood Oncology Group (DCOG) ALL-10 protocol in the Netherlands (October 2004 to April 2013), we conducted a nested case control study with 59 VTE cases and 118 controls to identify risk factors for VTE.

RESULTS

Fifty-nine of 778 ALL patients developed VTE (7.6%), with cerebral venous sinus thrombosis (CVST) in 26 of 59 patients (44.1%). VTE occurred during induction treatment in 59.3% (n = 35) and in 40.7% (n = 24) during medium risk intensification. Conditional multivariable logistic regression analysis showed that age and ALL subtype were significantly associated with VTE (age ≥7 years: OR 2.72, 95% CI 1.33-5.57; ALL subtype T-ALL: OR 2.95, 95% CI 1.02-8.57). A multivariable Cox model showed no association between the occurrence of VTE and event free survival. In CVST patients, permanent disability was present in 34.6%.

CONCLUSION

Within this large pediatric ALL cohort, we demonstrated a high morbidity in CVST patients. Age ≥7 years at diagnosis and T-ALL subtype were the main risk factors for VTE, and should be considered in preventive strategies.

Thrombosis in pediatric patients with leukemia

Acute lymphoblastic leukemia (ALL) is the most common type of cancer diagnosed in children. It is reportedly the most common malignancy associated with thromboembolism in the pediatric age group. Over the last 2 decades, venous thromboembolism (VTE) has been increasingly diagnosed among pediatric ALL patients with an estimated incidence ranging from about 5% (for symptomatic cases) to about 30-70% (following sequential imaging studies in asymptomatic children). The etiology is multifactorial and may stem from alterations of the hemostatic system following various chemotherapy protocols (including use of l-Asparaginase), the presence of central venous lines (CVL), as well as comorbidities, e.g. inherited thrombophilia risk factors. Most symptomatic thrombotic events occur in the upper venous system or in the central nervous system (CNS). Prospective studies on the establishment of guidelines for treatment or prevention are lacking. The following review will address the epidemiology, etiology and risk factors for thrombosis, describe the currently available evidence, and address issues associated with diagnosis and treatment.

Obesity and risk for venous thromboembolism from contemporary therapy for pediatric acute lymphoblastic leukemia

INTRODUCTION

Acute lymphoblastic leukemia (ALL) therapy confers risk for venous thromboembolism (VTE) and associated acute and long-term morbidity. Obesity increases VTE risk in the general population but its impact on ALL therapy-associated VTE is unknown.

METHODS

In a retrospective cohort of children treated for ALL between 2008 and 2016 (n = 294), we analyzed obesity at diagnosis (body mass index [BMI] ≥95%) and subsequent development of VTE. A subset participated in two concurrent prospective ALL trials studying body composition via dual-energy X-ray absorptiometry (DXA) (n = 35) and hypercoagulability via thromboelastography (TEG) (n = 46). Secondary analyses explored whether precise measurement of body fat and/or global hemostasis ex vivo by TEG could further delineate VTE risk in the obese.

RESULTS

Overall, we found 27/294 (9.2%) patients developed symptomatic VTE during therapy, 19/27 (70%) occurred during Induction. Study-defined "serious" VTE developed in 4/294 (1.4%) of patients. Obesity but not overweight was strongly predictive of symptomatic VTE (obesity odds ratio = 3.8, 95% confidence interval 1.5-9.6, p = 0.008). In the DXA subset, only 2/35 patients developed symptomatic VTE. However, within those prospectively screened during Induction, 30% (14/46) developed VTE; eight (17%) of these were asymptomatic and found only via screening.

CONCLUSIONS

In this pediatric ALL cohort, obesity conferred more than a three-fold increased risk for symptomatic VTE. In a subgroup of patients who underwent active screening, up to a third were noted to have VTE (symptomatic and asymptomatic). TEG did not predict VTE. Additional studies are necessary to validate these findings and to further refine a risk-stratified approach to thrombo-prevention during ALL therapy.

Epidemiology of venous thrombosis in children with cancer

There has been an extensive body of research focusing on the epidemiology of thrombosis in adult cancer populations; however, there is significantly less knowledge about thrombosis in paediatric cancer populations. Thrombosis is diagnosed with increasing frequency in children being treated for cancer, and there is an urgent need to increase our understanding of the epidemiology of thrombosis in this population. Currently, there are no guidelines for identification of high-risk groups, prophylaxis or management of thrombotic complications in paediatric cancer patients. We reviewed the available literature regarding the epidemiology, mechanisms, risk factors, prophylaxis and outcomes of thrombosis in children with cancer and identified areas that require further research. The reported incidence of symptomatic venous thromboembolism (VTE) in children with cancer ranges between 2.1% and 16%, while the incidence of asymptomatic events is approximately 40%. Approximately 30% of VTE in this population is associated with central venous lines (CVL). The most common location of VTE is upper and lower extremity deep venous thrombosis (43 to 50% of events, respectively), while 50% of events in ALL patients occur in the central nervous system. Key characteristics that increase the risk of thrombosis include the type of cancer, age of the patient, the presence of a CVL, presence of pulmonary/intra thoracic disease, as well as the type of chemotherapy. Outcomes for paediatric cancer patients with VTE include post-thrombotic syndrome, pulmonary embolism, recurrent thromboembolism, destruction of upper venous system and death. Prospective studies aimed at enabling risk stratification of patients are required to facilitate development of paediatric specific recommendations related to thromboprophylaxis in this population.

Venous thromboembolism in adults treated for acute lymphoblastic leukaemia: Effect of fresh frozen plasma supplementation

Treatment of acute lymphoblastic leukaemia (ALL) is frequently complicated by venous thromboembolism (VTE). The efficacy and optimal approach of VTE prevention are unclear, particularly in adult patients. We assessed the effect of thromboprophylaxis on symptomatic VTE incidence in cycle 1 of ALL treatment in adult patients. Secondly, we explored potential etiologic factors for VTE and the clinical impact of VTE on ALL outcome. We retrospectively assessed symptomatic VTE incidence and use of thromboprophylaxis in 240 adults treated for newly diagnosed ALL in the Dutch-Belgian HOVON-37 multicentre study (1999–2005). Potential etiologic factors were explored by analysis of patient and disease characteristics, impact of VTE on ALL outcome by analysis of complete remission and overall survival rates. Symptomatic VTE was observed in 24 of 240 patients (10%). Thromboprophylaxis differed by centre (prophylactic fresh frozen plasma (FFP) supplementation or no thromboprophylaxis) and was applied only during L-asparaginase in cycle 1. VTE incidence was significantly lower with FFP supplementation than without FFP (6% vs. 19%; adjusted odds ratio [OR] 0.28; 95% confidence interval [CI] 0.10–0.73). FFP did not influence antithrombin or fibrinogen plasma levels. Patients with VTE in cycle 1 had a significantly poorer complete remission rate (adjusted OR 0.18; 95% CI 0.07–0.50), particularly patients with cerebral venous thrombosis (adjusted OR 0.17; 95% CI 0.04–0.65). Our study suggests that prophylactic FFP supplementation effectively reduces symptomatic VTE incidence during ALL treatment in adults. This should be confirmed in a randomised controlled trial.

A minor role of asparaginase in predisposing to cerebral venous thromboses in adult acute lymphoblastic leukemia patients

Cerebral venous thrombosis (CVT) covers up to a third of all venous thromboses (VTs) detected in patients with acute lymphoblastic leukemia (ALL). It usually hampers patients' lives and may also endanger efficient leukemia treatment. Although many factors have been suggested to account for an elevated risk of VTs in patients with ALL, there still is a lack of studies focusing on CVTs and especially in the setting of adult ALL patients. We studied in our retrospective population-based cohort the occurrence, characteristics, as well as risk factors for VTs in 186 consecutively diagnosed Finnish adult ALL patients treated with a national pediatric-inspired treatment protocol ALL2000. In the risk factor analyses for VTs we found a distinction of the characteristics of the patients acquiring CVT from those with other kinds of VTs or without thrombosis. In contrast to previous studies we were also able to compare the effects of asparaginase in relation to CVT occurrence. Notably, more than half of the CVTs were diagnosed prior the administration of asparaginase which accentuates the role of other risk factors on the pathophysiology of CVT compared to truncal or central venous line (CVL) VTs in adult ALL patients.

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.

Venous Thromboembolism in Children with Cancer and Blood Disorders

Venous thromboembolism (VTE) in children is multifactorial and most often related to a combination of inherited and acquired thrombophilias. Children with cancer and blood disorders are often at risk for VTE due to disease-related factors such as inflammation and abnormal blood flow and treatment-related factors such as central venous catheters and surgery. We will review risk factors for VTE in children with leukemia, lymphoma, and solid tumors. We will also review risk factors for VTE in children with blood disorders with specific focus on sickle cell anemia and hemophilia. We will present the available evidence and clinical guidelines for prevention and treatment of VTE in these populations.

An Overview of Thrombophilia and Associated Laboratory Testing

Venous thromboembolism, usually entailing deep vein thrombosis, pulmonary embolism, or both, is a complex and multifactorial disorder, in which a number of putative conditions interplay and finally contribute to propel the individual risk over a certain degree, so ultimately culminating in the development of venous occlusive disorders. Thrombophilia is commonly defined as a propensity to develop venous thromboembolism on the basis of an underlying hypercoagulable state attributable to inherited or acquired disorders of blood coagulation or fibrinolysis. The thrombophilic conditions are conventionally classified as inherited (or genetically determined) and acquired. The former include deficiencies of natural anticoagulants such as antithrombin, protein C, protein S, increased values of clotting factors (especially factor VIII), as well as prothrombotic polymorphisms in genes encoding for factor V (i.e., factor V Leiden) and prothrombin. The latter conditions mainly entail antiphospholipid antibody syndrome, malignancy, acquired elevations of coagulation factors or acquired reduction of natural inhibitors, or hyperhomocysteinemia. Deepened knowledge of all potential risk factors, as well as the clear understanding of their role in the pathophysiology of venous thrombosis, are both essential to help achieve a faster and more efficient diagnosis of this condition as well as a more effective prophylaxis of patients at higher risk and treatment of those with manifest disease.

Venous thromboembolism prevention during asparaginase-based therapy for acute lymphoblastic leukemia

BACKGROUND

Venous thromboembolism (vte) is a recognized complication in patients treated with asparaginase-containing chemotherapy regimens; the optimal preventive strategy is unclear. We assessed the safety and efficacy of prophylaxis using low-dose low molecular weight heparin in adult patients with acute lymphoblastic leukemia in complete remission treated with an asparaginase-based post-remission chemotherapy regimen.

METHODS

As part of the intensification phase of the Dana-Farber Cancer Institute 91-01 regimen, asparaginase was administered weekly to 41 consecutive patients for 21-30 weeks; these patients also received prophylaxis with enoxaparin 40 mg daily (60 mg for patients ≥80 kg). Outcomes were assessed against outcomes in a comparable cohort of 99 patients who received the same chemotherapy regimen without anticoagulation prophylaxis.

RESULTS

The overall rate of symptomatic venous thrombosis was not significantly different in the prophylaxis and non-prophylaxis cohorts (18.92% and 21.74% respectively). Among patients receiving prophylaxis, vte occurred in higher proportion in those who weighed at least 80 kg (42.86% vs. 4.35%, p = 0.0070). No major bleeding complications occurred in the prophylaxis group (minor bleeding: 8.1%).

CONCLUSIONS

Prophylaxis with low-dose enoxaparin during the intensification phase was safe, but was not associated with a lower overall proportion of vte.

Outcomes Following Discontinuation of E. coli l-Asparaginase Upon Severe Allergic Reactions in Children With Acute Lymphoblastic Leukemia

BACKGROUND

Discontinuation of E. coli l-asparaginase in patients with acute lymphoblastic leukemia (ALL) is unavoidable upon severe allergic reaction. We sought to examine outcomes following E. coli l-asparaginase discontinuation due to severe allergic reactions.

PROCEDURE

We evaluated the outcome of children enrolled in Taiwan Pediatric Oncology Group-2002-ALL protocol between 2002 and 2012, who had E. coli l-asparaginase discontinued due to severe allergic reactions, and compared the outcomes of those who continued with Erwinia l-asparaginase (Erwinase) with those who did not.

RESULTS

Among 700 patients enrolled in this study, 33 patients had E. coli l-asparaginase treatment discontinued due to severe allergic reactions. Five-year overall survival did not differ significantly among the 648 patients without discontinuation (81 ± 1.6%, mean ± SE), compared to 17 patients with allergic reactions and treated with Erwinase (88 ± 7.8%) and 16 patients with allergic reactions but not treated with Erwinase (87 ± 8.6%). Among 16 patients who did not receive Erwinase, all 10 who received ≥50% of the scheduled doses of E. coli l-asparaginase before discontinuation survived without events.

CONCLUSIONS

Erwinase treatment may not be needed for some ALL patients with severe allergy to E. coli l-asparaginase if ≥50% of prescribed doses were received and/or therapy is augmented with other agents.

RUNX1 Amplification Increases the Risk for Thrombosis in Children With B-cell Acute Lymphoblastic Leukemia

BACKGROUND

RUNX1 (AML1) amplification in patients with B-cell acute lymphoblastic leukemia (B-ALL) has been associated with poor survival for unclear reasons. Our anecdotal experience suggests that children with B-ALL and RUNX1 amplification might be predisposed to thrombosis.

PROCEDURE

We performed a retrospective cohort study of children with B-ALL treated from 2008 to 2014 at the North Carolina Children's Hospital. Patient demographics, cytogenetics, and diagnosis of thrombosis were extracted by blinded chart review. Analysis was performed examining the relationship between RUNX1 amplification and thrombosis.

RESULTS

We identified 119 patients with B-ALL and a median age of 4.9 years (interquartile range, 2.9 to 8.6 y) at diagnosis. Four patients (3%) had RUNX1 amplification. The average number of RUNX1 copies among those with amplification was 5 (SD 0.81 [range, 4 to 6]). Eighteen thromboses were diagnosed within 6 months of starting treatment. These events were more likely among patients with RUNX1 amplification than in patients without amplification (75% vs. 13%; RR 5.75, 95% confidence interval, 2.75-12.01).

CONCLUSIONS

RUNX1 amplification may predispose to early thrombotic events in children with B-ALL which could, in part, contribute to their poorer outcomes. Treatment implications, including possible prophylactic anticoagulation of patients with of RUNX1 amplification, justify larger studies to confirm these findings.

Asparaginase-associated toxicity in children with acute lymphoblastic leukemia

Asparaginase is an integral component of multiagent chemotherapy regimens for the treatment of children with acute lymphoblastic leukemia. Positive outcomes are seen in patients who are able to complete their entire prescribed course of asparaginase therapy. Toxicities associated with asparaginase use include hypersensitivity (clinical and subclinical), pancreatitis, thrombosis, encephalopathy, and liver dysfunction. Depending on the nature and severity of the toxicity, asparaginase therapy may be altered or discontinued in some patients. Clinical hypersensitivity is the most common asparaginase-associated toxicity requiring treatment discontinuation, occurring in up to 30% of patients receiving Escherichia coli-derived asparaginase. The ability to rapidly identify and manage asparaginase-associated toxicity will help ensure patients receive the maximal benefit from asparaginase therapy. This review will provide an overview of the common toxicities associated with asparaginase use and recommendations for treatment management.

Best Practices in Adolescent and Young Adult Patients with Acute Lymphoblastic Leukemia: A Focus on Asparaginase

The inclusion of asparaginase in chemotherapy regimens to treat acute lymphoblastic leukemia (ALL) has had a positive impact on survival in pediatric patients. Historically, asparaginase has been excluded from most treatment protocols for adolescent and young adult (AYA) patients because of perceived toxicity in this population, and this is believed to have contributed to poorer outcomes in these patients. However, retrospective analyses over the past 12 years have shown that 2-, 5-, and 7-year overall survival of AYA patients is significantly improved with pediatric versus adult protocols. The addition of asparaginase to adult protocols yielded high rates of first remission and improved survival. However, long-term survival remains lower compared with what has been seen in pediatrics. The notion that asparaginase is poorly tolerated by AYA patients has been challenged in multiple studies. In some, but not all, studies, the incidences of hepatic and pancreatic toxicities were higher in AYA patients, whereas the rates of hypersensitivity reactions did not appear to differ with age. There is an increased risk of venous thromboembolic events, and management with anti-coagulation therapy is recommended. Overall, the risk of therapy-related mortality is low. Together, this suggests that high-intensity pediatric protocols offer an effective and tolerable approach to treating ALL in the AYA population.

L-Asparaginase lowers plasma antithrombin and mannan-binding-lectin levels: Impact on thrombotic and infectious events in children with acute lymphoblastic leukemia

BACKGROUND

L-asparaginase, a key therapeutic agent in the management of patients with acute lymphoblastic leukemia (ALL), dramatically impairs hepatic protein synthesis. We investigated the effects of prolonged exposure to L-asparaginase on antithrombin (AT), fibrinogen and mannan-binding-lectin (MBL) levels, and on the occurrence of thrombotic events (TE) and febrile neutropenia episodes (FN) in pediatric patients.

PROCEDURE

Protein levels were measured in 97 children during 30 weeks of chemotherapy with L-asparaginase and up to 1 year following remission. TE and FN episodes were recorded during this period.

RESULTS

Median AT level decreased from 0.96 IU/mL prior to treatment (range: 0.69-1.38) to 0.55 IU/mL (0.37-0.76) during therapy. Fibrinogen and MBL decreased from 3.18 g/L (1.29-7.28) and 1,177 ng/mL (57-5,343) to 1.56 g/L (0.84-2.13) and 193 ng/mL (57-544), respectively. All three proteins had recovered 1-4 weeks after L-asparaginase cessation. TE were reported in 22 (23%) patients. Of these, 11 occurred after a median of 10 administrations of L-asparaginase. Fifty-one FN were associated with infections, of which 36 occurred during treatment with L-asparaginase. Patients with low levels of MBL at diagnosis were at higher risk of FN associated with infections (RR = 1.59, 95%CI: 1.026-2.474). Both AT and MBL decreases were moderately correlated with fibrinogen (r = 0.51 and 0.58, respectively).

CONCLUSIONS

Children with ALL are exposed to significant decrease in AT, fibrinogen and MBL levels, and concomitant increased risk of thrombosis and FN with infection during L-asparaginase treatment. Measuring plasma levels of these liver-derived proteins could help predict the occurrence of adverse events.

Venous Thromboembolism Risk Assessment and Prophylaxis Use in Pediatric, Adolescent, and Young Adult Hematology Oncology Patients

No widely accepted method exists to evaluate pediatric hematology oncology patients for the risk of venous thromboembolism (VTE) and the need for prophylaxis. The use of a VTE risk-assessment tool and standardized guidelines for prophylaxis could increase the use of appropriate prophylaxis and reduce the number of VTEs in patients, thereby decreasing morbidity, mortality, hospitalization, and cost. The purpose of this project was to implement and assess the compliance of a pediatric-specific VTE risk-assessment tool in hospitalized pediatric, adolescent, and young adult hematology oncology patients. From the 114 pediatric, adolescent, and young adult patients requiring assessment, 91 (80%) VTE assessments were completed and 87 (96%) were completed accurately. Eighty percent of the at-risk patients were ordered VTE prophylaxis. The use of a VTE risk-assessment tool in pediatric hematology oncology patients is a feasible way to assess patients for their risk of developing a VTE.

Cerebrospinal fluid proteomics in children during induction for acute lymphoblastic leukemia: A pilot study

BACKGROUND

Thrombosis in patients with acute lymphocytic leukemia (ALL) can develop after treatment with L-asparaginase (asp) and is often localized to the central nervous system (CNS). We hypothesize that changes in the cerebrospinal fluid (CSF) proteome will occur after asp therapy and will anticipate CNS clots.

METHODS

Five newly diagnosed patients, ages 1-11 years, with ALL (n = 4) or lymphoblastic lymphoma (LL) (n = 1) underwent serial lumbar punctures during induction. CSF was depleted of abundant plasma proteins and analyzed by gel-free, label-free quantitative proteomics.

RESULTS

More than 600 proteins were quantified across all CSF samples. In four subjects, the expression of proteins involved in coagulation such as protein C Inhibitor (SERPINA5) and heparin cofactor II (SERPIND1) changed over the course of asp therapy. Antithrombin III (ATIII) and plasminogen (PLMN) levels were shown to have decreased expression over time in one child who developed a CNS thrombosis, compared to other subjects.

CONCLUSIONS

CSF proteomics is feasible and reproducible in ALL and LL. CSF ATIII and PLMN should be further investigated as predictive markers of CNS thrombosis.

ABO Group as a Thrombotic Risk Factor in Children With Acute Lymphoblastic Leukemia: A Retrospective Study of 523 Patients

Children with acute lymphoblastic leukemia (ALL) are at high risk of thrombotic complications, resulting from multiple risk factors (malignancy, chemotherapy, central venous access devices, and inherent host characteristics). Non-O blood groups have been associated with an increased risk of venous thromboembolism (VTE) in adults, with a compounding effect in the presence of thrombophilia or cancer. We hypothesized that among children with ALL receiving a standardized protocol, there would be an increased risk of thrombotic events in non-O compared with O blood group patients. In a retrospective study of 523 children with ALL from June 1995 to April 2013, there were 56 (10.7%) thromboembolic events. Patients with VTE were compared with the whole cohort, based on blood group, age, sex, leukemia phenotype, and clinical risk category. Among children with VTE, 42 (75%) had non-O and 14 (25%) had O blood group, compared with 302 (57.7%) non-O and 221 (42.3%) O blood groups in the cohort. Non-O blood group was confirmed as an independent risk factor for VTE in multivariate analysis. This is the first study to report a significant association between non-O blood groups and VTE in children with cancer.

Clinical Course of Cerebral Venous Thrombosis in Adult Acute Lymphoblastic Leukemia

BACKGROUND

Venous thromboembolism (VTE) is a frequent complication in patients with acute lymphoblastic leukemia (ALL). A significant proportion of patients develop cerebral venous thrombosis (CVT).

METHODS

To investigate risk factors for and the clinical course of CVT in ALL patients, we describe all cases of CVT which occurred in a well-defined cohort of 240 adults, treated for newly diagnosed ALL in the HOVON (Dutch-Belgian Hemato-Oncology Cooperative Group)-37 study. We conducted a nested case-control study to explore the relevance of early symptoms and risk factors for CVT in ALL patients.

RESULTS

Nine of 240 patients developed CVT (4%). CVT occurred during or shortly after L-asparaginase therapy (in 8 cases) and shortly after intrathecal methotrexate injections (in all cases) during cycle I of remission induction treatment. CVT was associated with prior headache and seizures. In 5 of 9 patients with CVT, headache before the diagnosis of CVT occurred within 3 days after lumbar puncture and initially had a postural character.

CONCLUSIONS

CVT is relatively common in adult ALL patients. Our data suggest that CVT in adult ALL patients results from the additive effects of multiple risk factors, with a particular role for asparaginase and the effects of lumbar punctures for intrathecal therapy.

Haemostatic alterations induced by treatment with asparaginases and clinical consequences

The benefit of asparaginase for treating acute lymphoid leukaemia (ALL) has been well established. Native asparaginase derives from Escherichia coli (colaspase) or Erwinia chrysanthemi (crisantaspase); in a third preparation, colaspase is pegylated. Depletion of asparagine leads to decreased synthesis of procoagulant, anticoagulant, and fibrinolytic proteins, with resultant hypercoagulability and greater risk of venous thromboembolism (VTE). Colaspase and crisantaspase are not dose-equivalent, with crisantaspase displaying haemostatic toxicity only at dosages much higher and administered more frequently than those of colaspase. Cerebral venous thrombosis and pulmonary embolism are two life-endangering manifestations that occur during treatment with asparaginase particularly in children and in adults with ALL, respectively. Approximately one-third of VTEs are located in the upper extremities and are central venous line-related. Other risk factors are longer duration of asparaginase treatment and concomitant use of prednisone, anthracyclines, and oral contraceptives. The risk associated with inherited thrombophilia is uncertain but is clearly enhanced by other risk factors or by the use of prednisone. VTE prevention with fresh frozen plasma is not recommended; the efficacy of antithrombin (AT) concentrates has occasionally been reported, but these reports should be confirmed by proper studies, and AT should not be routinely employed. Therapeutic or prophylactic heparin doses are only partially effective, and direct thrombin or factor Xa inhibitors could play significant roles in the near future.

Thrombosis as a complication of central venous access in pediatric patients with malignancies: a 5-year single-center experience

Background

Reliable central venous access (CVC) is essential for hematology–oncology patients since frequent puncture of peripheral veins—e.g., for chemotherapy, antibiotic administration, repeated blood sampling, and monitoring—can cause unacceptable pain and psychological trauma, as well as severe side effects in cases of extravasation of chemotherapy drugs. However, CVC lines still carry major risk factors, including thrombosis, infection (e.g., entry site, tunnel, and luminal infections), and catheter dislocation, leakage, or breakage.

Methods

Here we performed a retrospective database analysis to determine the incidence of CVC-associated thrombosis in a single-center cohort of 448 pediatric oncologic patients, and to analyze whether any subgroup of patients was at increased risk and thus might benefit from prophylactic anticoagulation.

Results

Of the 448 patients, 269 consecutive patients received a CVC, and 55 of these 269 patients (20%) also had a thrombosis. Of these 55 patients, 43 had at least one CVC-associated thrombosis (total number of CVC-associated thrombosis: n = 52). Among all patients, the median duration of CVC exposure was 464 days. Regarding exposure time, no significant difference was found between patients with and without CVC-associated thrombosis. Subclavia catheters and advanced tumor stages seem to be the main risk factors for the development of CVC-associated thrombosis, whereas pharmacologic prophylaxis did not seem to have a relevant impact on the rate of thrombosis.

Conclusions

We conclude that pediatric surgeons and oncologists should pay close attention to ensuring optimal and accurate CVC placement, as this appears the most effective tool to minimize CVC-associated complications.

Factor V Leiden 1691G/A and prothrombin gene 20210G/A polymorphisms as prothrombotic markers in adult Egyptian acute leukemia patients

Factor V Leiden 1691G/A and prothrombin gene 20210G/A mutations are the most common genetic defects leading to thrombosis. This work aimed to study the FV Leiden and the prothrombin gene polymorphism in adult Egyptian patients with acute leukemia and their importance in thrombophilia screening. The study included 76 patients with acute leukemia and 100 healthy controls. Genotyping was done by real-time polymerase chain reaction technique. For factor V Leiden, the frequency of G/A mutation conferred more than 2.5-fold of increased risk of (OR 2.639 95 % CI 1.045-6.669). The frequency of factor V Leiden combined (G/A + A/A) genotypes conferred 2.83-fold of increased risk (OR 2.828, CI 1.13-7.075), The A allele conferred almost threefold increased risk (OR 2.824, 95 % CI 1.175-6.785). Despite higher frequency in patients compared to controls, there was no risk of association between prothrombin gene mutation and acute leukemia in adult Egyptians nor was there between combined genotypes of prothrombin gene mutation and factor V Leiden.

Venous thromboembolism in children with cancer - a population-based cohort study

Introduction

Cancer is a known risk factor for venous thromboembolism (VTE) in adults, but population-based data in children are scarce.

Materials and methods

We conducted a cohort study utilising linkage of the Clinical Practice Research Database (primary care), Hospital Episodes Statistics (secondary care), UK Cancer Registry data and Office for National Statistics cause of death data. From these databases, we selected 498 children with cancer diagnosed between 1997 and 2006 and 20,810 controls without cancer. We calculated VTE incidence rates in children with cancer vs. controls, and hazard ratios (HRs) using Cox regression.

Results

We identified four VTE events in children with cancer compared with four events in the larger control population corresponding to absolute risks of 1.52 and 0.06 per 1000 person-years respectively. The four children with VTE and cancer were diagnosed with hematological, bone or non-specified cancer. Childhood cancer was hence associated with a highly increased risk of VTE (HR adjusted for age and sex: 28.3; 95%CI = 7.0-114.5).

Conclusions

Children with cancer are at increased relative risk of VTE compared to those without cancer. Physicians could consider thromboprophylaxis in children with cancer to reduce their excess risk of VTE however the absolute risk is extremely small and the benefit gained therefore would need to be balanced against the risk invoked of implementing such a strategy.

Novelty & Impact Statements

While there is a reasonable level of knowledge about the risk of VTE in adult populations, it is not well known whether this risk is reflected in paediatric patients. We found a substantial increase in risk of VTE in children with cancer compared to a child population without cancer. While this finding is important, the absolute risk of VTE is still low and must be balanced with the risks of anticoagulation.

Cerebral Sinus Venous Thrombosis due to Asparaginase Therapy

We report a 9-year-old boy with acute lymphoblastic leukemia (ALL) in high-risk group who suffered from left sided focal seizures and ipsilateral hemiparesis during his induction with Asparaginase chemotherapy. Superior sagittal sinus thrombosis and right frontal hemorrhage were demonstrated on brain magnetic resonance imaging (MRI) scans . Anticoagulation was initiated with unfractionated heparin and switched to low molecular weight heparin after 3 weeks and continued for 6 months. At one-year followup, he had complete response to chemotherapy for ALL, with residual mild left hemiparesis, and his MRI scans revealed recanalized venous sinuses. The case highlights the importance of considering cerebral venous thrombosis as a complication of Asparaginase therapy.