Thrombosis in children with acute lymphoblastic leukemia

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

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.

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

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

Timing of Central Venous Line Insertion During Induction in Children With Acute Lymphoblastic Leukemia

PURPOSE

Central venous lines (CVL) in children with acute lymphoblastic leukemia (ALL) provide comfortable administration of intensive chemotherapy and blood sampling. The optimal time for the insertion of CVL in patients with ALL during induction therapy is controversial. This study aimed to investigate the frequency of CVL-related complications in children with ALL concerning the time of CVL insertion.

PATIENTS AND METHODS

We reviewed the records of 52 pediatric ALL patients with CVL. CVL placement before or on treatment day 15 was defined as "early insertion", and after treatment day 15 was defined as "late insertion". Demographics, preoperative blood counts, type of central line, time of CVL placement, CVL-related complications, and blood counts during complications were all noted. All the data were collected from those with the first catheter use.

RESULTS

CVL was placed ≤15 days in 26 patients (50%) and after 15 days in 26 patients (50%). Regarding the infection rates, no statistical difference was found between early and late CVL-inserted groups ( P =n.s.). Five patients developed thrombosis, and risk was found to be similar between early and late CVL-inserted groups ( P =n.s.). Catheter-related mechanical complications were recorded in 7 patients (3 in early and 4 in late CVL-inserted group, ( P =n.s.).

CONCLUSION

The present study showed no relation between the timing of CVL placement during induction therapy and the occurrence of infection and thrombosis. Our results suggest that CVL can be placed safely at the time of diagnosis or early induction treatment to provide a comfortable administration of chemotherapy and decrease painful blood samplings.

Orthopaedic adverse events among adolescents and adults treated with asparaginase for acute lymphoblastic leukaemia

Osteonecrosis (ON) is a complication of acute lymphoblastic leukaemia (ALL) treatment with patient- (age, female sex, genetic polymorphisms, presence of metabolic syndrome) and treatment-specific (glucocorticoid type and schedule) risk factors described. The potential role of asparaginase in increasing risk of ON via effects on coagulation, lipid metabolism, and steroid clearance is now also recognised. Paediatric studies consistently identify age as a key risk factor for ON, with adolescents at higher risk than young children. Fewer studies comprehensively report on risk of ON in adults, but available evidence suggests that adolescents and young adults (AYAs) treated with corticosteroid and asparaginase-containing paediatric-inspired regimens are more at risk than older adults treated with paediatric-inspired or traditional adult regimens. There are few proven strategies to prevent or mitigate the severity of ON and other orthopaedic complications of ALL therapy. Future clinical trials should carefully ascertain orthopaedic adverse events in adults. Evidence-based guidelines should be developed for management of orthopaedic adverse events in adults being treated for ALL, especially high-risk AYAs being treated with paediatric-inspired regimens.

Hypersensitivity reactions to asparaginase therapy in acute lymphoblastic leukemia: immunology and clinical consequences

Asparaginase is commonly used in combination therapy of acute lymphoblastic leukemia. However, as an immunogenic protein, hypersensitivity reactions (HSRs) during asparaginase therapy are frequent, indicating the development of anti-asparaginase antibodies. These can be associated with diminished clinical effectiveness, including poorer survival. Therapeutic drug monitoring of serum asparaginase activity to confirm complete asparagine depletion is therefore crucial during asparaginase therapy. Switching to alternative types of asparaginase is recommended for patients experiencing HSRs or silent inactivation; those with HSRs or silent inactivation on Escherichia coli-derived asparaginases should switch to another preparation. However, prior global shortages of Erwinia asparaginase highlight the importance of alternative non-E. coli-derived asparaginase, including recombinant Erwinia asparaginase.

Orthopedic Toxicities Among Adolescents and Young Adults Treated on DFCI ALL Consortium Trials

Orthopedic toxicity was common in adolescent and young adult patients treated on DFCI Consortium ALL pediatric protocols.

Younger age and exposure to pegaspargase were associated with higher risk of ON, and patients with ON had superior OS.

Adolescent and young adult patients with acute lymphoblastic leukemia (ALL) have superior outcomes when treated on pediatric regimens. Pediatric ALL regimens rely heavily on corticosteroids and asparaginase and are known to increase the risk of osteonecrosis (ON) and fractures in children, particularly adolescents. Orthopedic toxicity among young adults treated on pediatric-inspired regimens is not well described. Here, we report the symptomatic orthopedic toxicities of patients aged 15 to 50 years treated on sequential Dana-Farber Cancer Institute ALL Consortium protocols. Among 367 patients with a median age of 23 years (range, 15-50 years; 68% aged <30 years), 60 patients were diagnosed with ON (5-year cumulative incidence, 17%; 95% confidence interval [CI], 13-22), and 40 patients experienced fracture (5-year cumulative incidence, 12%; 95% CI, 8-15). Patients aged <30 years were significantly more likely to be diagnosed with ON (5-year cumulative incidence, 21% vs 8%; P = .004). Patients treated more recently on pegaspargase-based protocols were significantly more likely to be diagnosed with ON compared with those treated on earlier trials with native Escherichia coli asparaginase (5-year cumulative incidence, 24% vs 5%; P < .001). Of the 54 ON events for which adequate information was available, surgery was performed in 25 (46%). Patients with ON had superior overall survival (OS) compared with those without (multivariable OS hazard ratio, 0.15; 95% CI, 0.05-0.46; P = .001; ON included as a time-varying exposure). Increased rates of orthopedic toxicity in late-generation protocols may be driven by the pharmacokinetic drug interaction between pegaspargase and dexamethasone, leading to higher dexamethasone exposure.

Thrombotic potential during pediatric acute lymphoblastic leukemia induction: Role of cell-free DNA

BACKGROUND

Thromboembolism affects up to 30% of children undergoing treatment for acute lymphoblastic leukemia (ALL). Increased thrombin generation has been reported in ALL, but the mechanisms remain elusive.

OBJECTIVE

We aimed to show that extracellular traps and cell-free DNA (cfDNA) promote thrombin generation in pediatric ALL.

METHODS

In a longitudinal single-center study, we recruited 17 consecutive pediatric ALL patients. Serial blood samples were collected at diagnosis and weekly during the 4-week induction phase of antileukemic chemotherapy. Healthy children (n = 14) and children with deep vein thrombosis (DVT; n = 7) or sepsis (n = 5) were recruited as negative and positive controls, respectively. In plasma, we measured endogenous thrombin generation potential (ETP) and components of extracellular traps, including cfDNA.

RESULTS

In patients with ALL, ETP was increased at baseline and remained significantly elevated throughout the induction therapy. Plasma levels of cfDNA were increased at baseline and during the first 3 weeks of induction therapy. The extent of enhancement of ETP and plasma cfDNA in patients with ALL was similar to that seen in patients with DVT or sepsis. Treatment of plasma with DNase 1 lowered ETP in patients with ALL at each time point but did not affect ETP in healthy controls.

CONCLUSION

We conclude that childhood ALL is associated with a prothrombotic milieu at the time of diagnosis that continues during induction chemotherapy, and cfDNA contributes to increased thrombogenic potential.

Disordered hemostasis associated with severely depressed fibrinolysis demonstrated using a simultaneous thrombin and plasmin generation assay during L-asparaginase induction therapy in pediatric acute lymphoblastic leukemia

BACKGROUND

L-asparaginase (L-Asp)-associated thromboembolisms are serious complications in pediatrics patients with acute lymphoblastic leukemia (ALL), especially at ≥10.0 years old, but the pathogenesis remains to be clarified.

PROCEDURE

We conducted a multicenter, prospective study of 72 patients with ALL aged 1.0 to 15.2 years treated with either a Berlin-Frankfurt-Münster (BFM) 95-ALL oriented regimen or Japan Association of Childhood Leukemia Study ALL-02 protocol. We divided patients into each treatment protocol and investigated the dynamic changes in coagulation and fibrinolysis using simultaneous thrombin and plasmin generation assay. Patients' plasma samples were collected at the prephase (T0), intermittent phase (T1), and postphase of L-Asp therapy (T2), and postinduction phase (T3). Measurements of endogenous thrombin potential (T-EP) and plasmin peak height (P-Peak) were compared to normal plasma.

RESULTS

None of the cases developed thromboembolisms. Median ratios of T-EP and P-Peak for the controls in the JACLS group were 1.06 and 0.87 (T0), 1.04 and 0.71 (T1), 1.02 and 0.69 (T2), and 1.20 and 0.92 (T3), respectively, while those in the BFM group were 1.06 and 1.00 (T0), 1.04 and 0.64 (T1), 1.16 and 0.58 (T2), and 1.16 and 0.85 (T3), respectively. In particular, P-Peak ratios were depressed at T1 and T2 compared to T0 in the BFM group (P < .01). Moreover, P-Peak ratios in patients ≥10.0 years old were lower at T1 in the BFM group (P = .02).

CONCLUSIONS

The results demonstrated that hemostatic dynamics appeared to shift to a hypercoagulable state with marked hypofibrinolysis associated with L-Asp therapy, especially in patients ≥10.0 years old following the BFM regimen.

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.

Venous Thrombosis in Children with Acute Lymphoblastic Leukemia Treated on DCOG ALL-9 and ALL-10 Protocols: The Effect of Fresh Frozen Plasma

Background  Venous thromboembolism (VTE) is an important complication for treatment of acute lymphoblastic leukemia (ALL) in children. Especially, ALL treatment, with therapeutics such as asparaginase and steroids, increases the thrombotic risk by reduction in procoagulant and anticoagulant proteins. Replacement of deficient natural anticoagulants by administration of fresh frozen plasma (FFP) may have a preventive effect on the occurrence of VTE.

Methods  We retrospectively analyzed all consecutive children (≤18 years) with ALL, treated on the Dutch Childhood Oncology Group (DCOG) ALL-9 and ALL-10 protocols at the Emma Children's Hospital Academic Medical Center between February 1997 and January 2012, to study the effect of FFP on VTE incidence, antithrombin and fibrinogen plasma levels, and VTE risk factors.

Results  In total, 18/205 patients developed VTE (8.8%; 95% confidence interval [CI]: 4.9–12.7%). In all patients, VTE occurred after asparaginase administration. In total, 82/205 patients (40%) received FFP. FFP supplementation did not prevent VTE or alter plasma levels of antithrombin or fibrinogen. In the multivariate analysis, VTE occurred significantly more frequently in children ≥12 years (odds ratio [OR]: 3.89; 95% CI: 1.29–11.73) and treated according to the ALL-10 protocol (OR: 3.71; 95% CI: 1.13–12.17).

Conclusion  FFP supplementation does not seem to be beneficial in the prevention of VTE in pediatric ALL patients. In addition, age ≥12 years and treatment according to the DCOG ALL-10 protocol with intensive and prolonged administration of asparaginase in combination with prednisone are risk factors. There is a need for effective preventive strategies in ALL patients at high risk for VTE.

Human Fibrinogen Concentrate and Fresh Frozen Plasma in the Management of Severe Acquired Hypofibrinogenemia in Children With Acute Lymphoblastic Leukemia: Results of a Retrospective Survey

OBJECTIVE OF THE STUDY

In this study we aimed to retrospectively evaluate how centers, belonging to the Associazione Italiana Ematologia e Oncologia Pediatrica (AIEOP), manage severe acquired hypofibrinogenemia in children with acute lymphoblastic leukemia, particularly evaluating the therapeutic role of human fibrinogen concentrate (HFC) and fresh frozen plasma (FFP).

METHODS

We conducted a survey among AIEOP centers; thereafter, we collected and analyzed data with regard to the treatment of episodes of severe acquired hypofibrinogenemia occurring during the induction and reinduction phases of the AIEOP-BFM ALL 2009 protocol.

RESULTS

In total, 15 of the 37 AIEOP centers invited to join the survey agreed to collect the data, with 10 and 5 centers declaring to react to severe acquired hypofibrinogenemia (<70 mg/dL) by administering HFC or FFP, respectively. Of the 150 episodes of severe hypofibrinogenemia occurring in 101 patients, 47.3% were treated with HFC and 52.7% with FFP, with a normalization of fibrinogen levels achieved in greater proportion and in a shorter amount of time in the HFC group as compared with the FFP group. None of the patients presented with bleeding or thrombosis during the observation period.

CONCLUSIONS

Even with the limitations of the retrospective nature of this study, HFC seems to be a safe and effective alternative to FFP for replacement therapy in case of severe hypofibrinogenemia in children with acute lymphoblastic leukemia.

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.

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.

Increased Risk of Thrombosis Associated with Peripherally Inserted Central Catheters Compared with Conventional Central Venous Catheters in Children with Leukemia

OBJECTIVE

To study the risk of catheter-associated thrombosis (CAT) between peripherally inserted central catheters (PICCs) and tunneled central venous catheters in children with leukemia.

STUDY DESIGN

We analyzed all PICCs and conventional tunneled catheters placed in patients aged <18 years and admitted to our institute for leukemia treatment between February 2008 and April 2014. Cases of symptomatic CAT were confirmed by ultrasound and treated with low-molecular-weight heparin.

RESULTS

During the study period, 157 PICCs and 138 conventional tunneled catheters were placed in 192 patients with leukemia. CAT incidence was 1.5% (n = 2) in the conventional tunneled catheter group and 10.2% (n = 16) in the PICC group. The OR for CAT occurrence after PICC vs conventional tunneled catheter placement was 5.6 (95% CI, 1.2-26.5).

CONCLUSION

Our results suggest that the use of PICCs in children with leukemia increases the risk of CAT in comparison with the use of conventional tunneled catheters. Further randomized controlled studies are needed to characterize this risk and to better define indications.

Impact of baseline clinical and laboratory features on the risk of thrombosis in children with acute lymphoblastic leukemia: A prospective evaluation

BACKGROUND

Children with acute lymphoblastic leukemia (ALL) have increased risk of thromboembolism (TE). However, the predictors of ALL-associated TE are as yet uncertain.

OBJECTIVE

This exploratory, prospective cohort study evaluated the effects of clinical (age, gender, ALL risk group) and laboratory variables (hematological parameters, ABO blood group, inherited and acquired prothrombotic defects [PDs]) at diagnosis on the development of symptomatic TE (sTE) in children (aged 1 to ≤18) treated on the Dana-Farber Cancer Institute ALL 05-001 study.

PROCEDURES

Samples collected prior to the start of ALL therapy were evaluated for genetic and acquired PDs (proteins C and S, antithrombin, procoagulant factors VIII (FVIII:C), IX, XI and von Willebrand factor antigen levels, gene polymorphisms of factor V G1691A, prothrombin gene G20210A and methylene tetrahydrofolate reductase C677T, anticardiolipin antibodies, fasting lipoprotein(a), and homocysteine).

RESULTS

Of 131 enrolled patients (mean age [range] 6.4 [1-17] years) 70 were male patients and 20 patients (15%) developed sTE. Acquired or inherited PD had no impact on the risk of sTE. Multivariable analyses identified older age (odds ratio [OR] 1.13; 95% confidence interval [CI]: 1.01, 1.26) and non-O blood group (OR 3.64, 95% CI: 1.06, 12.51) as independent predictors for development of sTE. Patients with circulating blasts had higher odds of developing sTE (OR 6.66; 95% CI: 0.82, 53.85).

CONCLUSION

Older age, non-O blood group, and presence of circulating blasts, but not PDs, predicted the risk of sTE during ALL therapy. We recommend evaluation of these novel risk factors in the development of ALL-associated TE. If confirmed, these easily accessible variables at diagnosis can help develop a risk-prediction model for ALL-associated TE.

Deep vein thrombosis in pediatric patients

Due to advances in caring for critically ill children and those with chronic diseases, rates of deep vein thrombosis (DVT) are increasing in children. Risk factors consist of central venous catheters, chronic medical conditions, thrombophilia, and various medications. Compression Doppler ultrasonography is the method most commonly used to diagnose DVT, and patients will usually present with pain and swelling of the affected limb. Anticoagulation via subcutaneous injection is the most common treatment regime for children with DVT, and the new, direct oral anticoagulants are currently under investigation. Prevention techniques are not established, but clinical studies are addressing this need.

Increasing Incidence and Recurrence Rate of Venous Thromboembolism in Paediatric Oncology Patients in One Single Centre Over 25 Years

Venous thromboembolism (VTE) is a serious complication in paediatric oncology patients. To identify the incidence, risk factors and recurrence rate of VTE in paediatric oncology patients, an observational, retrospective cohort study of all consecutive children (≤18 years) with malignancies, treated at the Emma Children's Hospital Academic Medical Centre between January 1989 and December 2013, was done. A matched case-control study in children with lymphomas was performed, to identify thrombotic risk factors. Cumulative recurrence-free survival after first VTE was estimated by the Kaplan-Meier method. Of the 2,183 children included (male: female = 1.4:1.0; median age, 6.6 years) with cancer, 78 patients developed VTE (3.6%; 95% confidence interval [CI], 2.8-4.4). The incidence increased from 0.8% (4/478, 95% CI, 0.0-1.6) between 1989 and 1993 to 10.4% (44/423, 95% CI, 7.6-13.4) between 2009 and 2013. Independent risk factors for VTE were age ≥ 12 years, acute lymphoblastic leukaemia (ALL) and lymphoma. The case-control study in lymphoma patients showed a trend for increased VTE incidence in stage IV lymphoma. Twelve (15.4%) patients developed recurrent thrombosis, 7 patients while on therapeutic or prophylactic anticoagulation. The cumulative recurrence-free survival after first VTE was 88.5, 87.1 and 80.6% after 1, 5 and 10 years, respectively. In conclusion, we demonstrated an increasing incidence of VTE in children with malignancies, with age ≥ 12 years, ALL and lymphoma as independent risk factors. The elevated recurrence rate underlines the importance of full anticoagulant therapy and might warrant prophylactic anticoagulation after first VTE during cancer treatment.

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.

Safe Use of Low-Molecular-weight Heparin in Pediatric Acute Lymphoblastic Leukemia and Lymphoma Around Lumbar Punctures

Children with acute lymphoblastic leukemia or lymphoma (ALL) undergo multiple lumbar punctures (LPs) and frequently require low-molecular-weight heparin (LMWH) for thromboembolic complications. We evaluated if withholding LMWH 24 hours before and after LPs prevented bleeding complications. Children (n=133) with ALL from who were: (1) treated at St. Jude Children's Research Hospital, (2) received LMWH (2×/day of ~1 mg/kg) between January 2004 until December 2012, and (3) underwent a LP were analyzed. Spinal hematoma was defined as a clinical suspicion leading to diagnostic imaging. Traumatic LP was defined as ≥10 red blood cells per microliter of cerebrospinal fluid. In 1708 LPs, no hematomas occurred. For each child treated with LMWH, the probability of experiencing a spinal hematoma during the entire ALL treatment course was 0% (95% confidence interval [CI], 0.0%-2.7%), and in each LP, assuming no intrapatient correlation, the probability of spinal hematoma was 0% (95% CI, 0.0%-0.2%). Traumatic LPs were more common when performed when children were not receiving LMWH therapy (odds ratio [OR], 1.5; 95% CI, 1.1-2.2) which may be explained by clinician optimization of known risk factors for traumatic cerebrospinal fluid before the procedures. Withholding LMWH for 24 hours before and after LPs in children being treated for ALL is safe.

Complications and management of coagulation disorders in leukemia patients

Patients with leukemia are predisposed to various coagulation abnormalities. Thrombosis and bleeding continue to be a major cause of morbidity and mortality in leukemias. The pathophysiology of these disorders is unique, and not only the disease but also the treatment and other factors play a role. There has been an increase in the understanding of these disorders in leukemias. However, it is still difficult to predict when and which patients will have these complications. The evidence for the management of coagulation abnormalities in leukemias is still evolving and not as established as in solid malignancies. The management of these disorders is complex, and making clinical decisions is often challenging. In the era of specialization, where there are different hematologists looking after benign- and malignant-hematology patients, opinions of thrombosis experts are often sought by leukemia specialists. This review aims to bridge the gap in the knowledge of these disorders between these specialists.

TropicALL study: Thromboprophylaxis in Children treated for Acute Lymphoblastic Leukemia with Low-molecular-weight heparin: a multicenter randomized controlled trial

Background

Venous thromboembolism (VTE) is a common and severe complication during treatment of acute lymphoblastic leukemia (ALL). An important cause is the intensive use of asparaginase. Prospective cohort studies in which prophylactic low-molecular-weight heparin (LMWH) was used to prevent VTE showed lower VTE risk than in historic control cohorts, with a negligible bleeding risk. However, the efficacy of thromboprophylaxis with LMWH during ALL treatment has never been investigated in a randomized design. Here, we present the protocol of a randomized controlled trial in which the efficacy and safety of thromboprophylaxis with high prophylactic dose LMWH versus no thromboprophylaxis will be assessed in children treated for primary ALL with asparaginase.

Methods/Design

Thromboprophylaxis in Children treated for Acute Lymphoblastic Leukemia with Low-molecular-weight heparin (TropicALL) is a multicenter, randomized controlled open-label trial conducted in the Netherlands. Patients between 1 and 19 years of age with primary ALL, who are treated within the Dutch Childhood Oncology Group (DCOG) ALL-11 or 12 study will be randomized to thromboprophylaxis with LMWH once daily, (dose of 85 IU/kg (intervention arm A)), or to no thromboprophylaxis (arm B, standard of care) during asparaginase courses of ALL treatment. Primary efficacy endpoint is symptomatic objectified VTE during ALL treatment; secondary efficacy endpoints are overall survival and the composite of symptomatic and asymptomatic objectified VTE. Primary safety endpoints are major bleeding, clinically relevant non-major bleeding and minor bleeding. A total of 324 patients will be included to obtain a relative risk reduction of 75% with a power of 80%, using a two-sided test with significance level α = 0.05.

Discussion

This trial will be the first to assess efficacy and safety of thromboprophylaxis with LMWH during asparaginase treatment for ALL in children in a randomized design.

Trail registration

Nederlands Trial Register NTR4707. Registered 30 July 2014.

Evaluation for inherited and acquired prothrombotic defects predisposing to symptomatic thromboembolism in children with acute lymphoblastic leukemia: a protocol for a prospective, observational, cohort study

BACKGROUND

Thromboembolism (TE) is a serious complication in children with acute lymphoblastic leukemia (ALL). The incidence of symptomatic thromboembolism is as high as 14% and case fatality rate of ~15%. Further, development of thromboembolism interferes with the scheduled chemotherapy with potential impact on cure rates. The exact pathogenesis of ALL-associated thromboembolism is unknown. Concomitant administration of asparaginase and steroids, two important anti-leukemic agents, is shown to increase the risk of ALL-associated TE. Dana-Farber Cancer Institute (DFCI) ALL studies reported ~10% incidence of thrombosis with significantly increased risk in older children (≥10 yrs.) and those with high-risk ALL. The majority (90%) of thromboembolic events occurred in the Consolidation phase of therapy with concomitant asparaginase and steroids when high-risk patients (including all older patients) receive higher dose steroids. Certain inherited and acquired prothrombotic defects are known to contribute to the development of TE. German investigators documented ~50% incidence of TE during therapy with concomitant asparaginase and steroids, in children with at least one prothrombotic defect. However, current evidence regarding the role of prothrombotic defects in the development of ALL-associated TE is contradictory. Although thromboprophylaxis can prevent thromboembolism, ALL and it's therapy can increase the risk of bleeding. For judicious use of thromboprophylaxis, identifying a population at high risk for TE is important. The risk factors, including prothrombotic defects, predisposing to thrombosis in children with ALL have not been defined.

METHODS

This prospective, observational cohort study aims to evaluate the prevalence of inherited prothrombotic defects in children with ALL treated on DFCI 05-01 protocol and the causal relationship of prothrombotic defects in combination with patient and disease-related factors to the development of TE. We hypothesize that the combination of prothrombotic defects and the intensive therapy with concomitant high dose steroids and asparaginase increases the risk of TE in older patients and patients with high-risk ALL.

DISCUSSION

The results of the proposed study will help design studies of prophylactic anticoagulant therapy. Thromboprophylaxis given to a targeted population will likely reduce the incidence of TE in children with ALL and ultimately improve their quality of life and prospects for cure.

Venous thromboembolism following L-asparaginase treatment for lymphoid malignancies in Korea

Essentials Data on venous thromboembolism (VTE) after L-asparaginase (L-asp) in Asian lymphoma are scarce. This is a population-based study in Asian patients with lymphoid disease and L-asp-related VTE. The overall incidence of L-asp-associated VTE was similar to reports on Caucasians. This first and largest study in Asians shows that mainly adult patients are at risk of thrombosis.

SUMMARY

Background L-asparaginase (L-asp)-associated venous thromboembolism (VTE) is a serious adverse complication associated with acute lymphoblastic leukemia (ALL) and lymphoma treatment. The incidence rate of L-asp-related VTE in Asian cancer patients is not well known. Methods We performed a population-based study between 2009 and 2013 using claim databases, including both diagnostic and medication codes, such as anti-cancer treatment with L-asp and VTE diagnoses from the starting date until 3 months after cessation of L-asp. Results A total of 3286 patients were prescribed L-asp treatment for any type of lymphoid malignancy including ALL and lymphoma; 116 patients (3.5%) experienced VTE. The most common site of thrombosis was the upper extremities (34.5%). Cerebral vein thrombosis (1.7%) occurred in two pediatric patients; 2.4% (43/1795) of pediatric patients and 4.9% (72/1486) of adult patients suffered from VTE, respectively; 2.7% (56/2064) of ALL and 4.9% (59/1217) of lymphoma patients were diagnosed with VTE after L-asp exposure. After univariate analysis, both the diagnosis of lymphoma (vs. ALL) and being an adult patient (vs. pediatric patient) were risk factors for VTE occurrence. However, after multivariate analysis, only age > 18 remained a risk factor for VTE (odds ratio, 1.79; 95% confidence interval, 1.14-2.81). Conclusions This is the first and largest population-based study in Asian patients with lymphoid malignancies treated with L-asp demonstrating that adult patients are at elevated risk of thrombosis after L-asp exposure. The overall incidence of L-asp-related VTE amongst these patients was similar to that in Caucasian populations.

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.

Acute Lymphoblastic Leukemia in a Young Adult Presenting as Hepatitis and Acute Kidney Injury

Acute lymphoblastic leukemia (ALL) in adults is a relatively rare malignancy. The typical presentation includes signs and symptoms associated with bone marrow failure, including fevers, infections, fatigue, and excessive bruising. In this article, we report an unusual systemic presentation of ALL in a previously healthy 18-year-old man. He initially presented with several-day history of nausea and vomiting, 10-pound weight loss, and right upper quadrant abdominal pain with evidence of acute hepatocellular liver injury (elevations in aspartate aminotransferase/alanine aminotransferase) and elevation in serum creatinine. Further history revealed that he just joined the Marine Corp; in preparation, he had been lifting weights and taking protein and creatine supplements. A complete serological evaluation for liver disease was negative and creatine phosphokinase was normal. His aspartate aminotransferase and alanine aminotransferase declined, and he was discharged with expected improvement. However, he returned one week later with continued symptoms and greater elevation of aminotransferases. Liver biopsy was nondiagnostic, revealing scattered portal and lobular inflammatory cells (primarily lymphocytes) felt to be consistent with drug-induced liver injury or viral hepatitis. Given his elevated creatinine, unresponsive to aggressive volume expansion, a kidney biopsy was performed, revealing normal histology. He subsequently developed an extensive left lower extremity deep venous thrombosis. Given his deep venous thrombosis, his peripheral blood was sent for flow cytometry, which revealed lymphoblasts. Bone marrow biopsy revealed 78% blasts with markers consistent with acute B-cell lymphoblastic leukemia. This report emphasizes that right upper quadrant abdominal pain with liver test abnormalities may be the initial presentation of a systemic illness such as ALL.

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.

Prevalence of Symptomatic and Asymptomatic Thrombosis in Pediatric Oncology Patients With Tunneled Central Venous Catheters

BACKGROUND

Pediatric oncology patients with tunneled central venous catheters (CVCs) are at increased risk to develop venous thromboembolic events (VTEs), but the true prevalence of (a)symptomatic VTE is unknown. Aim of this study was to evaluate the prevalence of (a)symptomatic VTE in pediatric oncology patients with tunneled CVCs.

PROCEDURE

All patients were included in the Aristocaths study: a randomized controlled multicenter trial investigating the prophylactic effect of 70% ethanol locks on CVC-associated bloodstream infections (CABSIs) were eligible for this study. We assessed the following outcomes: (i) symptomatic VTE and (ii) asymptomatic CVC-related VTE (using ultrasound [US]). Follow-up was 6 months, unless patients developed one of the following events: VTE, CABSI, CVC removal, or death.

RESULTS

We included 305 patients (hematologic malignancy, n = 148; solid tumor, n = 157), median age 9 years (range, 1-18 years). Symptomatic VTE was detected in 8 of 305 patients (2.6%; 95% confidence interval [CI]: 1.1-5.1%), which was related to the CVC in three patients. Patients (185/305) were evaluated with US: 11 of 185 (5.9%; 95% CI: 3.0-10.4%) patients had asymptomatic CVC-related VTE.

CONCLUSIONS

Prevalence of both symptomatic VTE and asymptomatic CVC-related VTE was low compared to other studies, which may be explained by the inclusion of patients with solid tumors, reduction of CABSI by ethanol, use of tunneled CVCs, and use of US.

High-dose corticosteroid associated with catheter-related thrombosis after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients are at an increased risk of thrombotic complications, most of which are catheter-related and present a substantial challenge. The incidence of CRT varies considerably depending on clinical factors. However, the underlying pathogenesis and risk factors remain unclear.

METHODS

We performed a retrospective nested case-control study in patients following allo-HSCT. Thrombotic episodes were diagnosed based on the clinical suspicion of the physician (pain, swelling, etc.) with subsequent CVC or PICC thrombosis confirmed via duplex ultrasound. Cases with CRT and controls were matched for time of HSCT, age at HSCT, donor source and type of insertion (CVCs or PICC).

RESULTS

During the 8-year period, catheters were placed in 2896 patients, with a total of 40 patients (1.38%) developed CRT, among which 11 were associated with CVCs and 29 were associated with PICCs. The median duration from catheter insertion to thrombosis was 97days. Despite reports of an association between thrombosis and infection, central line-associated bloodstream infection was comparable between groups. No significant differences were noted in terms of primary disease, donor type, conditioning regimen or catheter type between the cases and controls. A multivariate regression analysis identified high-dose corticosteroids as independent risk factors for the development of CRT. CRT seems to negatively affect prognosis in allo-HSCT patients.

CONCLUSION

In conclusion, we demonstrate that the use of high-dose corticosteroids is correlated with the onset of CRT. However, the efficacy and safety of thromboprophylaxis in this population require further investigation.

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.

Incidence and risk factors for Central Nervous System thrombosis in paediatric acute lymphoblastic leukaemia during intensive asparaginase treatment: a single-centre cohort study

Central Nervous System (CNS) thrombosis is a complication of acute lymphoblastic leukaemia (ALL) treatment that is potentially associated with significant morbidity and neurological sequelae. Its presumably multifactorial aetiology is poorly characterized. We conducted a single-centre, retrospective cohort study on 346 ALL paediatric patients (1-16 years old) treated with asparaginase intensive Dana Farber Cancer Institute (DFCI) protocols from 1998 to 2011. The incidence, risk factors and outcome of CNS thrombosis were evaluated. CNS thrombosis occurred in 3·8% (13/346) of the patients (95% confidence interval 2·0-6·3%). Twelve events were diagnosed during intensification, all of which resolved within 2 weeks without neurological sequelae or significant impact in survival. Obesity (body mass index above 95th percentile) and asparaginase formulation were the only factors associated with CNS thrombosis, with an increase in the odds of event in obese patients [odds ratio (OR) = 3·37; P = 0·064] and a reduction in patients receiving Erwinia asparaginase (OR = 0·12; P = 0·018). No association could be demonstrated for age, gender, DFCI risk-group, ALL phenotype, steroid or doxorubicin use, central venous line use or CNS radiotherapy. CNS thrombosis is a rare but manageable adverse event without significant sequelae or detrimental effects in survival. Increased awareness is recommended in obese patients particularly during intensive asparaginase use.

Asparaginase Potentiates Glucocorticoid-Induced Osteonecrosis in a Mouse Model

Osteonecrosis is a common dose-limiting toxicity of glucocorticoids. Data from clinical trials suggest that other medications can increase the risk of glucocorticoid-induced osteonecrosis. Here we utilized a mouse model to study the effect of asparaginase treatment on dexamethasone-induced osteonecrosis. Mice receiving asparaginase along with dexamethasone had a higher rate of osteonecrosis than those receiving only dexamethasone after 6 weeks of treatment (44% vs. 10%, P = 0.006). Similarly, epiphyseal arteriopathy, which we have shown to be an initiating event for osteonecrosis, was observed in 58% of mice receiving asparaginase and dexamethasone compared to 17% of mice receiving dexamethasone only (P = 0.007). As in the clinic, greater exposure to asparaginase was associated with greater plasma exposure to dexamethasone (P = 0.0001). This model also recapitulated other clinical risk factors for osteonecrosis, including age at start of treatment, and association with the systemic exposure to dexamethasone (P = 0.027) and asparaginase (P = 0.036). We conclude that asparaginase can potentiate the osteonecrotic effect of glucocorticoids.

Severe Cerebral Vasospasm and Childhood Arterial Ischemic Stroke After Intrathecal Cytarabine

We report on 2 patients who developed widespread cerebral vasospasm and arterial ischemic strokes (AIS) after application of intrathecal (IT) cytarabine. In a 3-year-old child with acute lymphoblastic leukemia (ALL), left leg weakness, hyperreflexia, and clonus were noted 4 days after her first dose of IT cytarabine during the induction phase of her chemotherapy. Cerebral MRI revealed multiple acute cerebral ischemic infarcts and widespread cerebral vasospasm. A 5-year-old girl complained of right arm and leg pain and began limping 11 days after IT cytarabine. Symptoms progressed to right dense hemiplegia, left gaze deviation, headache, and speech arrest. MRI revealed 2 large cortical areas of diffusion restriction in the right frontal and left parietal lobes. Cerebral magnetic resonance angiography (MRA) showed irregular narrowing affecting much of the intracranial arterial circulation. Although the first child fully recovered from her neurologic symptoms, the second patient had persistent hemiplegia on follow-up. Including this report, there are now 4 pediatric ALL cases of severe cerebral vasospasm and AIS in the context of IT cytarabine administration, strongly suggesting a true association. Differential diagnosis and management issues are discussed. Along with the more widespread use of MRI and MRA, the true frequency of this severe adverse effect will become clearer in future. For any child with neurologic symptoms within hours or days of receiving IT cytarabine, a low threshold for cerebral imaging with MRI and MRA is recommended.

The development of thromboembolism may increase the risk of osteonecrosis in children with acute lymphoblastic leukemia

Previous studies indicate pathophysiological and epidemiological parallels between osteonecrosis (ON) and thromboembolism (TE), two common treatment-related morbidities in acute lymphoblastic leukemia (ALL). To elucidate risk factors for ON and explore the relationship between ON and TE, we undertook a retrospective study of children (n = 208) with ALL. Twenty-one (10.1%) children developed ON and 42 (20.2%) TE on therapy. Thromboembolism was a significant predictor of ON on univariate (OR 8.85) and multivariate analysis, along with older age and PEGylated asparaginase. This observation supports a role for hypercoagulability in the pathogenesis of ON. Larger prospective studies are needed to further test these findings.

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.

Von Willebrand Factor and Factor VIII levels in Egyptian children with newly diagnosed acute lymphoblastic leukemia in relation to peripheral blast cells and steroid therapy

BACKGROUND

Endothelial dysfunction has been reported in children with acute lymphoblastic leukemia (ALL). The aim of this study is to assess Von Willebrand Factor antigen (VWF antigen) and Factor VIII (FVIII) in newly diagnosed ALL patients, in relation to peripheral blast (PB) cells, steroid therapy, and any prognostic potential.

PROCEDURE

VWF antigen and FVIII were assessed initially (D0) and at day 8 (D8) steroid therapy for 32 newly diagnosed ALL patients with and without peripheral blood blast cells.

RESULTS

At diagnosis, patients with PBs had a significantly higher levels of VWF antigen (102.7 ± 22.9% vs. 56.9 ± 8%, P<0.001) and FVIII (93.4 ± 15.9% vs. 6 62.6 ± 18.1%, P<0.001) than those without. Following steroid therapy, both factors decreased in those with PBs, whereas an increase above baseline was observed in those without PBs. Furthermore, there was a significant positive correlation between PBs and both VWF antigen (P<0.001) and FVIII levels (P=0.002). High-risk patients were comparable with standard-risk group in mean values of VWF antigen (P=0.234) and FVIII (P=0.891) at diagnosis. After 12 months from diagnosis, all patients without PB achieved and maintained complete remission. Those with initial PB reported relapse (12.5%) or death (4.2%) during follow-up.

CONCLUSIONS

Markers of endothelial dysfunction namely VWF and FVIII were related to circulating blast cells and steroids therapy through lysis of lymphoblasts results in reduction of both factors, with risk of thrombosis during induction with marked disintegration of malignant cells.

Thrombosis and hemostatic abnormalities in hematological malignancies

There is a paucity of data that pertain to thrombosis in patients with hematological malignancies. Recent studies showed that patients with lymphoma, multiple myeloma, and acute leukemia have an increased thrombotic risk, particularly at the time of diagnosis and during chemotherapy. We searched the PubMed database for articles on thromboembolic complications in patients with hematological malignancies published between 1996 and 2013. The incidence of thrombotic events is variable, and is influenced by the type and the stage of hematological malignancy, the antitumor therapy, and the use of central venous devices. The pathogenesis of thromboembolic disease in hematological malignancies is multifactorial. Tumor cell-derived procoagulant, fibrinolytic, or proteolytic factors, and inflammatory cytokines affect clotting activation, and chemotherapy and immunomodulatory drugs increase the thrombotic risk in patients with lymphoma, acute leukemia, and multiple myeloma. Infections might also contribute to the pathogenesis of the thromboembolic complications: endotoxins from gram-negative bacteria induce the release of tissue factor, tumor necrosis factor and interleukin-1b, and gram-positive organisms can release bacterial mucopolysaccharides that directly activate factor XII. In the setting of plasma cell dyscrasias, hyperviscosity, decreased fibrinolysis, procoagulant autoantibody production, inflammatory cytokines, acquired activated protein C resistance, and the prothrombotic effects of antimyeloma agents might be the cause of thromboembolic complications. Anticoagulant therapy is very complicated because of high risk of hemorrhage. Therefore, an accurate estimate of a patient's thrombotic risk is essential to allow physicians to target thromboprophylaxis in high-risk patients.

Management of thrombotic complications in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common type of cancer diagnosed in children, and has been reported as the most common malignancy associated with thromboembolism in the pediatric age group. Treatment with Escherichia coli asparaginase, concomitant steroids, presence of central venous lines, and thrombophilic abnormalities are established risk factors for thromboembolism. The incidence varies with age, co-morbidities and chemotherapy regimens but the risk is highest during the induction and intensification phases. Treatment is necessary in majority of children to prevent serious sequelae. Mortality from thromboembolic events in any location is 2 to 4 % and the risk of recurrence is 7 to 10 %, further enhanced in the setting of malignancy. Randomized trials of venous thromboembolism (VTE) management in pediatric patients with ALL are lacking due to the low overall incidence, resulting in considerable variation in practice. The objective of this article is to review current knowledge on the treatment and prevention of thrombosis associated with pediatric ALL.

Systemic treatments for the prevention of venous thrombo-embolic events in paediatric cancer patients with tunnelled central venous catheters

BACKGROUND

Venous thrombo-embolic events (VTEs) occur in 2.2% to 14% of paediatric cancer patients and cause significant morbidity and mortality. The malignant disease itself, the cancer treatment and the presence of central venous catheters (CVCs) increase the risk of VTE.

OBJECTIVES

The primary objective of this review was to investigate the effects of preventive systemic treatments in paediatric cancer patients with tunnelled CVCs on (a)symptomatic VTE. Secondary objectives of this review were to investigate adverse effects of systemic treatments for the prevention of (a)symptomatic VTE in paediatric cancer patients with tunnelled CVCs; and to investigate the effects of systemic treatments in the prevention of (a)symptomatic VTE with CVC-related infection in paediatric cancer patients with tunnelled CVCs.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 8 2012), MEDLINE (1966 to August 2012) and EMBASE (1966 to August 2012). In addition, we searched reference lists from relevant articles and conference proceedings of the International Society for Paediatric Oncology (SIOP) (from 2006 to 2011), the American Society of Clinical Oncology (ASCO) (from 2006 to 2011), the American Society of Hematology (ASH) (from 2006 to 2011) and the International Society of Thrombosis and Haematology (ISTH) (from 2006 to 2011). We scanned the International Standard Randomised Controlled Trial Number (ISRCTN) Register and the National Institute of Health (NIH) Register for ongoing trials (www.controlled-trials.com) (August 2012), and we contacted the authors of eligible studies if additional information was required.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) comparing systemic treatments to prevent venous thrombo-embolic events (VTEs) in paediatric cancer patients with tunnelled CVCs with a control intervention or no systemic treatment. For the description of adverse events, cohort studies were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, extracted data and performed risk of bias assessment of included studies. Analyses were performed according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

Three RCTs and three CCTs (including 1291 children) investigated the prevention of VTE (low molecular weight heparin (LMWH) n = 134, antithrombin (AT) supplementation n = 37, low-dose warfarin n = 31, cryoprecipitate and/or fresh frozen plasma (FFP) supplementation n = 240, AT supplementation and LMWH n = 41). AT, cryoprecipitate and FFP were supplemented only in cases of AT or fibrinogen deficiency. Of the six included RCTs/CCTs, five investigated the prevention of VTE compared with no intervention (n = 737), and one CCT compared AT supplementation and LMWH with AT supplementation (n = 71). All studies had methodological limitations, and clinical heterogeneity between studies was noted.We found no significant effects of systemic treatments compared with no intervention in preventing (a)symptomatic VTE and no differences in adverse events (such as major and/or minor bleeding; none of the studies reported thrombocytopenia, heparin-induced thrombocytopenia (HIT), heparin-induced thrombocytopenia with thrombosis (HITT), death as a result of VTE, removal of CVC due to VTE, CVC-related infection, and post-thrombotic syndrome (PTS)) between experimental and control groups. Two studies with comparable participant groups and interventions were included for meta-analyses (n = 182). In the experimental group, 1/68 (1.5%) children were diagnosed with symptomatic VTE, as were 4/114 (3.5%) in the control group (best case scenario: risk ratio (RR) 0.65, 95% confidence interval (CI) 0.09 to 4.78). These studies also evaluated asymptomatic CVC-related VTE: In the experimental group, 22/68 (32.4%) were diagnosed with asymptomatic VTE, as were 35/114 (30.7%) in the control group (best case scenario: RR 1.02, 95% CI 0.40 to 2.55). Heterogeneity was substantial for this analysis: I(2) = 73%.The attribution of LMWH to AT supplementation resulted in a significant reduction in symptomatic VTE (Fisher's exact test, two-sided P = 0.028) without bleeding complications; asymptomatic VTE, thrombocytopenia, HIT, HITT, death as a result of VTE, removal of CVC due to VTE, CVC-related infection and PTS were not assessed.Four cohort studies were included for the evaluation of adverse events. Three studies provided information on bleeding episodes: One participant developed an ischaemo-haemorrhagic stroke. One study provided information on other adverse events: None occurred.

AUTHORS' CONCLUSIONS

We found no significant effects of systemic treatments compared with no intervention in preventing (a)symptomatic VTE in paediatric oncology patients with CVCs. However, this could be a result of the low number of included participants, which resulted in low power. In one CCT, which compared one systemic treatment with another systemic treatment, we identified a significant reduction in symptomatic VTE with the addition of LMWH to AT supplementation.All studies investigated the prevalence of major and/or minor bleeding episodes, and none found a significant difference between study groups. None of the studies reported thrombocytopenia, HIT, HITT, death as a result of VTE, removal of CVC due to VTE, CVC-related infection or PTS among participants.On the basis of currently available evidence, we are not able to give recommendations for clinical practise. Additional well-designed international RCTs are needed to further explore the effects of systemic treatments in preventing VTE. Future studies should aim for adequate power with attainable sample sizes. The incidence of symptomatic VTE is relatively low; therefore, it might be necessary to select participants with thrombotic risk factors or to investigate asymptomatic VTE instead.