A prospective cohort study determining the prevalence of thrombotic events in children with acute lymphoblastic leukemia and a central venous line who are treated with L-asparaginase: results of the Prophylactic Antithrombin Replacement in Kids with Acute Lymphoblastic Leukemia Treated with Asparaginase (PARKAA) Study

Thromboprophylaxis in Children: Navigating Uncharted Waters

The rising incidence of pediatric thrombosis, increasing nearly 10% annually over the past decade, underlines a need for effective preventive strategies, particularly in hospitalized children. This narrative review explores existing literature on venous thromboembolism prevention in pediatric patients to clarify current strategies in children undergoing general, orthopaedic, and Fontan surgeries, and with conditions such as acute lymphoblastic leukemia and gastrointestinal disease. While recent studies have provided some insights into potential preventive strategies, real evidence is lacking on the best practices for thromboprophylaxis in these patient groups. In the absence of substantial studies, clinicians must rely on individual assessments weighting thrombotic and bleeding risk to effectively and safely manage these "uncharted waters."

Thrombotic Complications in Pediatric Cancer

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

Epidemiology of clinically unsuspected venous thromboembolism in children with cancer: A population-based study from Maritimes, Canada

Inconsistencies in the definition of clinically unsuspected venous thromboembolism (VTE) in pediatric patients recently led to the recommendation of standardizing this terminology. Clinically unsuspected VTE (cuVTE) is defined as the presence of VTE on diagnostic imaging performed for indications unrelated to VTE in a patient without symptoms or clinical history of VTE. The prevalence of cuVTE in pediatric cancer patients is unclear. Therefore, the main objective of our study was to determine the prevalence of cuVTE in pediatric cancer patients. All patients 0-18 years old, treated at the IWK in Halifax, Nova Scotia, from August 2005 through December 2019 with a known cancer diagnosis and at least one imaging study were eligible (n = 743). All radiology reports available for these patients were reviewed (n = 18,120). The VTE event was labeled a priori as cuVTE event for radiology reports that included descriptive texts indicating a diagnosis of thrombosis including thrombus, central venous catheter-related, thrombosed aneurysm, tumor thrombosis, non-occlusive thrombus, intraluminal filling defect, or small fragment clot for patients without documentation of clinical history and or signs of VTE. A total of 18,120 radiology reports were included in the review. The prevalence of cuVTE was 5.5% (41/743). Echocardiography and computed tomography had the highest rate of cuVTE detection, and the most common terminologies used to diagnose cuVTE were thrombus and non-occlusive thrombus. The diagnosis of cuVTE was not associated with age, sex, and type of cancer. Future efforts should focus on streamlining radiology reports to characterize thrombi. The clinical significance of these cuVTE findings and their application to management, post-thrombotic syndrome, and survival compared to cases with symptomatic VTE and patients without VTE should be further studied.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

IMPACT

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

Preclinical evaluation of engineered L-asparaginase variants to improve the treatment of Acute Lymphoblastic Leukemia

INTRODUCTION

Escherichia coli l-asparaginase (EcA), an integral part of multi-agent chemotherapy protocols of acute lymphoblastic leukemia (ALL), is constrained by safety concerns and the development of anti-asparaginase antibodies. Novel variants with better pharmacological properties are desirable.

METHODS

Thousands of novel EcA variants were constructed using protein engineering approach. After preliminary screening, two mutants, KHY-17 and KHYW-17 were selected for further development. The variants were characterized for asparaginase activity, glutaminase activity, cytotoxicity and antigenicity in vitro. Immunogenicity, pharmacokinetics, safety and efficacy were tested in vivo. Binding of the variants to pre-existing antibodies in primary and relapsed ALL patients' samples was evaluated.

RESULTS

Both variants showed similar asparaginase activity but approximately 24-fold reduced glutaminase activity compared to wild-type EcA (WT). Cytotoxicity against Reh cells was significantly higher with the mutants, although not toxic to human PBMCs than WT. The mutants showed approximately 3-fold lower IgG and IgM production compared to WT. Pharmacokinetic study in BALB/c mice showed longer half-life of the mutants (KHY-17- 267.28±9.74; KHYW-17- 167.41±14.4) compared to WT (103.24±18). Single and repeat-doses showed no toxicity up to 2000 IU/kg and 1600 IU/kg respectively. Efficacy in ALL xenograft mouse model showed 80-90 % reduction of leukemic cells with mutants compared to 40 % with WT. Consequently, survival was 90 % in each mutant group compared to 10 % with WT. KHYW-17 showed over 2-fold lower binding to pre-existing anti-asparaginase antibodies from ALL patients treated with l-asparaginase.

CONCLUSION

EcA variants demonstrated better pharmacological properties compared to WT that makes them good candidates for further development.

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

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

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.

IL16 and factor V gene variations are associated with asparaginase-related thrombosis in childhood acute lymphoblastic leukemia patients

Aim: We previously conducted exome-wide association study in acute lymphoblastic leukemia patients and identified association of five SNPs with asparaginase-related thrombosis. Here we aimed to replicate these findings in an independent patient cohort and through analyses in vitro. Patients & methods: SNPs located in IL16, MYBBP1A, PKD2L1, RIN3 and MPEG1 genes were analyzed in patients receiving Dana-Farber Cancer Institute acute lymphoblastic leukemia treatment protocols 05-001 and 11-001. Thrombophilia-related variations were also analysed. Results: IL16 rs11556218 conferred higher risk of thrombosis and higher in vitro sensitivity to asparaginase. The association was modulated by the treatment protocol, risk group and immunophenotype. A crosstalk between factor V Leiden, non-O blood groups and higher risk of thrombosis was also seen. Conclusion: IL16 and factor V Leiden variations are implicated in asparaginase-related thrombosis.

Venous thromboembolism incidence associated with pegylated asparaginase (ASP) compared to the native L-ASP: A retrospective analysis with an ASP-based protocol in adult patients with acute lymphoblastic leukaemia

Venous thromboembolism (VTE) is a well-known complication in patients with acute lymphoblastic leukaemia (ALL) receiving asparaginase (ASP)-based chemotherapy, including the ASP-intensive Dana-Farber Cancer Institute (DFCI) 91-01 protocol for adults. Since 2019, native L-ASP is no longer available in Canada and was replaced by pegylated (PEG)-ASP. To determine whether the incidence of VTE has changed since switching from L-ASP to PEG-ASP, we conducted a single-centred retrospective cohort study. We included 245 adult patients with Philadelphia chromosome negative ALL between 2011 and 2021, with 175 from the L-ASP group (2011-2019) and 70 from the PEG-ASP group (2018-2021). During Induction, 10.29% (18/175) of patients who received L-ASP developed VTE, whereas 28.57% (20/70) of patients who received PEG-ASP developed VTE (p = 0.0035; odds ratio [OR] 3.35, 95% confidence interval [CI] 1.51-7.39), after adjusting for line type, gender, history of VTE, platelets at diagnosis. Similarly, during Intensification, 13.64% (18/132) of patients had VTE on L-ASP while 34.37% (11/32) of patients on PEG-ASP developed VTE (p = 0.0096; OR 3.96, 95% CI 1.57-9.96 with multivariable analysis). We found that PEG-ASP is associated with a higher incidence of VTE compared to L-ASP, both during Induction and Intensification, despite the administration of prophylactic anticoagulation. Further VTE mitigation strategies are needed in particular for adult patients with ALL receiving PEG-ASP.

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.

Asparaginase: How to Better Manage Toxicities in Adults

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

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.

Microbial cancer therapeutics: A promising approach

The success of conventional cancer therapeutics is hindered by associated dreadful side-effects of antibiotic resistance and the dearth of antitumor drugs' selectivity and specificity. Hence, the conceptual evolution of anti-cancerous therapeutic agents that selectively target cancer cells without impacting the healthy cells or tissues, has led to a new wave of scientific interest in microbial-derived bioactive molecules. Such strategic solutions may pave the way to surmount the shortcomings of conventional therapies and raise the potential and hope for the cure of wide range of cancer in a selective manner. This review aims to provide a comprehensive summary of anti-carcinogenic properties and underlying mechanisms of bioactive molecules of microbial origin, and discuss the current challenges and effective therapeutic application of combinatorial strategies to attain minimal systemic side-effects.

Multiple Complications Secondary to L-asparaginase In a Child with Philadelphia-Chromosome-Positive Acute Lymphoblastic Leukemia: Case Report with Review of Literature

Even though L-asparaginase remains an essential drug for the treatment of childhood acute lymphoblastic leukemia (ALL), its use is associated with several unique toxicities. In this care report, we discuss a young boy with ALL who developed multiple complications simultaneously, including pancreatitis, gastrointestinal perforation, and left ventricular thrombus secondary to L-asparaginase during induction chemotherapy. Patient received immediate surgical intervention for the perforation and was commenced on anticoagulation therapy for the thrombus but eventually expired. This report highlights the importance of being aware of toxicities secondary to the use of L-asparaginase. Multiple complications secondary to L-asparaginase have been rarely reported previously and can be fatal.

Direct oral anticoagulants for use in paediatrics

With the increasing incidence of thromboembolism in children and improvement in management for patients with medically complex diseases, expanded availability of safe and effective anticoagulant medications is needed. Traditionally, the most common anticoagulants used for the treatment or prevention of venous thromboembolism or embolic stroke in children were either unfractionated heparin or the low-molecular-weight heparins. These medications require either intravenous access or daily subcutaneous injections, in addition to multiple venepunctures to monitor drug concentrations. Direct oral anticoagulants provide an alternative, and potentially safer, choice for children, as they are available in oral formulations and do not require drug monitoring. With the approval of the direct factor Xa inhibitor, rivaroxaban (by the European Medicines Agency and Health Canada), and the direct thrombin inhibitor, dabigatran (by the European Medicines Agency and US Food and Drug Administration), the field of paediatric anticoagulation is changing. In this Review, we provide an overview of the four direct oral anticoagulants approved in adults for the treatment and prevention of thrombosis and the completed and ongoing paediatric trials.

Markers of hypercoagulability in children with newly diagnosed acute lymphoblastic leukemia

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Thrombosis and Anticoagulant Therapy Among Pediatric Cancer Patients: Real-Life Data

Background: Venous thromboembolism (VTE) in children is relatively rare, and more so among those with cancer. In this study, we report the characteristics and outcomes of children with cancer-associated thrombosis.

Methods: We reviewed institutional databases for all children with cancer and a diagnosis of VTE at King Hussein Cancer Center in Jordan. Variables reviewed are patients’ clinical characteristics, treatment for cancer, and anticoagulation therapy.

Results: Between January 2011 and December 2018, a total of 45 patients fulfilled the inclusion criteria, and the median age was 10.4 (0.8-17.9) years. The most common underlying diagnosis was acute lymphoblastic leukemia (n = 13, 29%). At the time of VTE, 29 (64.4%) patients were receiving chemotherapy, and eight (17.8%) had a central venous catheter (CVC). The majority of patients (n = 37, 82%) developed VTE within 30 days of hospitalization. Thrombosis mostly involved the extremities (n = 23, 51%) and sagittal vein (n = 12, 26.7%). All patients were treated with low-molecular-weight heparin (LMWH), complicated by bleeding in three (6.6%) patients.

Conclusion: In contrast to adults, VTE in pediatric cancer patients is more associated with chemotherapy and recent hospitalization. LMWH is a safe and effective therapy for children with cancer who develop VTE.

Venous Thromboembolism in Pediatric Cancer Patients with Central Venous Catheter-A Systematic Review and Meta-analysis

Pediatric cancer patients hold an increased risk of venous thromboembolism (VTE) due to their cancer. Central venous catheters (CVCs) further increase the VTE risk. This systematic literature review elucidates the VTE incidence in pediatric cancer patients with CVC. MEDLINE and EMBASE were searched in August 2020 without time limits. We included studies reporting original data on patients ≤18 years with any CVC type and any cancer type, who were examined for VTE with ≥7 days follow-up. In total, 682 unique records were identified, whereof 189 studies were assessed in full text. Altogether, 25 studies were included, containing 2,318 pediatric cancer patients with CVC, of which 17% suffered VTE. Fifteen studies (n = 1,551) described CVC-related VTE and reported 11% CVC-related VTE. Concerning cancer type, 991 children suffered from acute lymphoblastic leukemia (ALL) and 616 from solid tumors. Meta-analysis revealed VTE incidence (95% confidence interval) of 21% (8-37) for ALL and 7% (0.1-17) for solid tumors. Additionally, 20% of children with tunneled or nontunneled CVC and 12% of children with implantable ports suffered VTE. In conclusion, pediatric cancer patients with CVC have substantial VTE risk. Children with ALL and CVC have higher VTE incidence than children with solid tumors and CVC. Implantable port catheter should be preferred over tunneled or nontunneled CVC to reduce VTE risk. Thrombophilia investigation does not seem relevant in pediatric cancer patients with CVC and VTE. To prevent VTE, intensified catheter care is recommended, especially in children with ALL.

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.

In Vitro Inhibitory Effect of Recombinant Human Calprotectin on Nalm6 Leukemia Cell Line

BACKGROUND & PURPOSE

In evaluating new drugs for the treatment of various types of cancer, investigations have been made to discover a variety of anti-tumor compounds with less side effects on normal cells. Investigations have shown that the heterodimers S100A8 and S100A9 inhibit the enzyme casein kinase 2 and then prevent the activation of the E7 oncoprotein. Therefore, the aim of this study was to evaluate the effect of calprotectin as an antitumor compound on the Nalm6 (B cell precursor leukemia cell line).

MATERIALS & METHODS

Transformation of genes encoding S100A8 and S100A9 human, designed in the pQE32 plasmid, was performed by the thermal shock method into E. coli M15 bacteria. After bacterial growth in LB medium, the expression of two S100A8 and S100A9 subunits, the solubility of the protein by SDS-PAGE method was determined. Finally, the S100A8 / A9 complex was equally placed in the microtube. In the next step, the cytotoxic effects of calprotectin produced on the Nalm6 cell line were evaluated using the wst1 test. Then, the apoptosis in these cells was measured using flow cytometry methods with Annexin-V coloration.

RESULTS

In the current study, the results showed that the cytotoxic effects of Calprotectin are time and concentration- dependent. Therefore, it can reduce the tumor expression and had a beneficial effect by induced apoptosis in Nalm6 cell line.

CONCLUSION

Calprotectin has an anti-tumor effect on the Nalm6 cell line by increasing apoptosis.

Pegaspargase in Practice: Minimizing Toxicity, Maximizing Benefit

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

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.

Neurological complications of pediatric cancer

Both the onset of various malignancies as well as the treatment of cancer can lead to neurologic symptoms which can be difficult to diagnose. In this review, we highlight the varied ways in which neurologic sequelae of cancer and its treatment manifest in children. Initial neurologic presentation may be secondary to mass effect or to immune-mediated paraneoplastic syndromes. Treatment effects on the nervous system may arise from surgery, chemotherapy, radiation, or bone marrow transplantation. In addition, the rapidly expanding field of immunotherapies for cancer has generated numerous new approaches to eradicating cancer including monoclonal antibodies, checkpoint inhibitors, and chimeric antigen receptor T cells (CAR-T cells), which have neurologic side effects mediated by immune responses that are also being recognized. Here we review common consult questions to the neurologist and our general approach to these scenarios including altered mental status, headaches, seizures, and sensorimotor complaints, considering the multifactorial nature of each.

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

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

Cancer and Tumor-Associated Childhood Stroke: Results From the International Pediatric Stroke Study

BACKGROUND

The prevalence of cancer among children with stroke is unknown. This study sought to evaluate cancer- and tumor-associated childhood ischemic stroke in a multinational pediatric stroke registry.

METHODS

Children aged 29 days to less than 19 years with arterial ischemic stroke or cerebral sinovenous thrombosis enrolled in the International Pediatric Stroke Study between January 2003 and June 2019 were included. Data including stroke treatment and recurrence were compared between subjects with and without cancer using Wilcoxon rank sum and chi-square tests.

RESULTS

Cancer or tumor was present in 99 of 2968 children (3.3%) with arterial ischemic stroke and 64 of 596 children (10.7%) with cerebral sinovenous thrombosis. Among children in whom cancer type was identified, 42 of 88 arterial ischemic stroke cases (48%) had brain tumors and 35 (40%) had hematologic malignancies; 45 of 58 cerebral sinovenous thrombosis cases (78%) had hematologic malignancies and eight (14%) had brain tumors. Of 54 cancer-associated arterial ischemic stroke cases with a known cause, 34 (63%) were due to arteriopathy and nine (17%) were due to cardioembolism. Of 46 cancer-associated cerebral sinovenous thrombosis cases with a known cause, 41 (89%) were related to chemotherapy-induced or other prothrombotic states. Children with cancer were less likely than children without cancer to receive antithrombotic therapy for arterial ischemic stroke (58% vs 80%, P = 0.007) and anticoagulation for cerebral sinovenous thrombosis (71% vs 87%, P = 0.046). Recurrent arterial ischemic stroke (5% vs 2%, P = 0.04) and cerebral sinovenous thrombosis (5% vs 1%, P = 0.006) were more common among children with cancer.

CONCLUSIONS

Cancer is an important risk factor for incident and recurrent childhood stroke. Stroke prevention strategies for children with cancer are needed.

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.

Epidemiology and outcomes of clinically unsuspected venous thromboembolism in children: A systematic review

BACKGROUND

Clinically unsuspected venous thromboembolic events (uVTE) detected during routine imaging pose a management challenge due to limited knowledge about their clinical significance. Unsuspected VTE are often referred as "asymptomatic," "incidental," or "clinically silent/occult" VTE.

OBJECTIVE

To understand the epidemiology, management, and outcomes of uVTE in children.

METHODS

A systematic review was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The search criteria included controlled vocabulary and keywords for VTE, incidental findings, and children (ages ≤ 21 years).

RESULTS

Among 10 875 articles, 51 studies (8354 children with 758 uVTE) were selected. The studies were heterogeneous, I2 96%; P < .0001. Unsuspected VTE were diagnosed in two settings: first, asymptomatic VTE (aVTE) diagnosed through surveillance imaging for VTE (46 studies; n = 5894; aVTE: 715, pooled frequency: 19%, 95% confidence interval [CI]: 13%-24%); second, incidental VTE (iVTE) diagnosed during imaging performed for indications without primary suspicion for VTE (6 studies; n = 2460; iVTE: 43). The majority (94%) of aVTE were associated with central venous lines (CVL). Non-CVL settings included post-spinal surgery, post-splenectomy, trauma, nephrotic syndrome, and newborns. In general, aVTE were reported to have a benign clinical course, were mostly transient, and resolved without intervention and with few immediate or long-term functional complications. Incidental VTE were primarily detected in children with cancer and ranged from tumor-associated thrombi to pulmonary embolism (PE) with insufficient evidence to draw meaningful conclusions about their management.

CONCLUSION

Clinically uVTE were predominantly diagnosed with CVL and their outcomes were generally favorable implying limited benefit of routine surveillance and thromboprophylaxis. Prospective research is needed to clarify the optimal management of iVTE.

Peripherally inserted central catheters lead to a high risk of venous thromboembolism in children

Venous thromboembolism (VTE) incidence in children has sharply increased with the majority of cases secondary to central venous catheters (CVCs). Among CVCs, the number of peripherally inserted central catheters (PICCs) placed has risen significantly. In this multicenter, prospective, observational cohort study, we enrolled patients aged 6 months to 18 years with newly placed PICCs or tunneled lines (TLs). We evaluated the incidence of VTE, central line-associated bloodstream infections (CLABSIs), and catheter malfunctions in PICCs and TLs, and risk factors of CVC-related VTE. A total of 1967 CVCs were included in the analysis. The incidence of CVC-related VTE was 5.9% ± 0.63%. The majority of the cases, 80%, were in subjects with PICCs, which had a significantly higher risk of catheter-related VTE than subjects with TLs (hazard ratio [HR] = 8.5; 95% confidence interval [CI], 3.1-23; P < .001). PICCs were significantly more likely to have a CLABSI (HR = 1.6; 95% CI, 1.2-2.2; P = .002) and CVC malfunction (HR = 2.0; 95% CI, 1.6-2.4; P < .001). Increased risk of CVC-related VTE was found in patients with a prior history of VTE (HR = 23; 95% CI, 4-127; P < .001), multilumen CVC (HR = 3.9; 95% CI, 1.8-8.9; P = .003), and leukemia (HR = 3.5; 95% CI, 1.3-9.0; P = .031). Children with PICCs had a significantly higher incidence of catheter-related VTE, CLABSI, and CVC malfunction over TLs. The results suggest that pause be taken prior to placing CVCs, especially PICCs, due to the serious complications they have been shown to cause.

Thromboembolism prophylaxis during L-asparaginase therapy in acute lymphoblastic leukemia - time to reconsider current approaches?

Acute Lymphoblastic Leukemia (ALL) is the commonest malignancy in childhood with a second incidence peak in adulthood. Improvements in pediatric therapy including the addition of L-asparaginase (L-ASP) have enabled cure rates in excess of 90% to be achieved in children. More recently L-ASP-containing pediatric protocols are being used to treat younger adults with ALL and have improved survival by approximately 2-fold. However, a toxicity associated with L-ASP-containing therapy in ALL is venous thromboembolism (VTE) which is associated with significant morbidity in this patient population and results in interruptions in L-ASP therapy that can impact on survival outcomes. The incidence of VTE among adult patients with ALL receiving L-ASP containing therapy has been reported to be as high as 43%. Despite this, there is a lack of evidence-based recommendations for VTE prophylaxis in this clinical context; low-molecular weight heparin (LMWH) and/or AT replacement have mostly been used. The low-quality data and inconveniences associated with these VTE prophylaxis regimens highlight the need to evaluate alternatives such as direct oral anticoagulants for the prevention of L-ASP-associated VTE in ALL. This narrative will review the body of evidence on primary thromboprophylaxis in adult patients with ALL receiving L-ASP containing therapy.

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.

[Management of toxicities associated with pegaspargase in treatment of patients with lymphoid malignancy: experience from 443 cases in a single center]

目的

总结培门冬酶治疗淋巴系统肿瘤的不良反应以及处理经验。

方法

通过回顾性分析北京同仁医院血液科2011年8月至2015年12月使用培门冬酶患者的临床资料，总结培门冬酶相关的不良反应以及处理经验。

结果

129例患者使用培门冬酶，累计共使用443例次，不良反应发生情况：2例（1.6%）患者出现过敏反应；19例（14.7%）患者发生胰腺炎（其中包括6例急性症状性胰腺炎、13例单纯胰酶升高的化学性胰腺炎），15例（11.6%）患者出现高甘油三酯血症，85例（65.9%）患者出现高血糖，7例（5.4%）患者出现低血糖；25例（19.4%）患者出现2级以上的转氨酶增高，21例（15.5%）患者发生高胆红素血症，62例（48.1%）患者发生低白蛋白血症；61例（47.3%）患者出现APTT延长，22例（17.1%）患者出现PT延长，15例（11.6%）患者出现TT延长，75例（58.1%）患者出现低纤维蛋白原血症，有11例患者（8.5%）出现血栓事件，有3例（2.3%）患者出现活动性出血。以上不良反应，分别经过抗过敏、抑制胰液分泌、降脂、降糖、保肝、补充血浆、止血等对症治疗后症状均好转。部分严重不良反应影响培门冬酶的按计划应用甚至导致停用。

结论

培门冬酶的不良反应非常广泛，有些非常严重，需要治疗时密切监测。

Thrombotic Risk from Chemotherapy and Other Cancer Therapies

Cancer patients have an increased risk of thrombosis. The development of cancer thrombosis is dependent on a number of factors including cancer type, stage, various biologic markers, and the use of central venous catheters. In addition, cancer treatment itself may increase thrombotic risk. Tamoxifen increases the risk of venous thromboembolism (VTE) by two- to sevenfold, while an impact on risk of arterial thrombosis is uncertain. Immunomodulatory imide drugs (IMiDs) such as thalidomide and lenalidomide increase the risk of VTE in patients with multiple myeloma (MM) by about 10-40% when given in combination with glucocorticoids or other chemotherapy agents; the risk of VTE in MM patients treated with IMiD-containing regimens necessitates that such patients receive thromboprophylaxis with aspirin, low-molecular-weight heparin, or warfarin. Among cytotoxic chemotherapy agents, cisplatin, and to a lesser extent fluorouracil, has been described in association with thrombosis. L-asparaginase in treatment of acute lymphoblastic leukemia is significantly associated with increased thrombosis particularly affecting the CNS, which may be due to acquired antithrombin deficiency; at some centers, plasma infusions or antithrombin replacement is used to mitigate this. Bevacizumab, an inhibitor of vascular endothelial growth factor, increases arterial and possibly venous thrombotic risk, although the literature is conflicting about the latter. Supportive care agents in cancer care, such as erythropoiesis-stimulating agents, granulocyte colony stimulating factor, and steroids, also have some impact on thrombosis. This review summarizes the mechanisms by which these and other therapies modulate thrombotic risks and how such risks may be managed.

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.

Acquired Hypofibrinogenemia Before Asparaginase Exposure During Induction Therapy for Pediatric Acute Lymphoblastic Leukemia: A Report of 2 Cases and Review of the Literature

Coagulopathy in pediatric leukemia patients is typically associated with acute promyelocytic leukemia or after asparaginase use in acute lymphoblastic leukemia. Rarely seen in acute lymphoblastic leukemia, we report 2 patients who presented with normal coagulation markers, but subsequently developed severe hypofibrinogenemia and bleeding in induction before administration of asparaginase. In both cases, cryoprecipitate was administered as initial treatment for bleeding associated with the hypofibrinogenemia. One patient was refractory to cryoprecipitate replacement and required treatment with human fibrinogen concentrate due to the persistence of hypofibrinogenemia with significant bleeding. The hypofibrinogenemia was transient in both cases and resolved within a few weeks.

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.

Neurological Complications of the Treatment of Pediatric Neoplastic Disorders

Neurological complications resulting from childhood cancer treatments are common. Treatment for childhood neoplastic disorders is often multimodal and may include procedures, cranial irradiation, chemotherapy, transplant, and immunotherapy, each of which carries distinct neurological risks. Procedures, such as lumbar punctures, are commonly used in this population for diagnostic purposes as well as intrathecal medication administration. Surgery is associated with an array of potential neurological complications, with posterior fossa syndrome being a common cause of morbidity in pediatric brain tumor patients after neurosurgical resection. Cranial irradiation can cause late neurological sequelae such as stroke, cerebral vasculopathy, secondary malignancy, and cognitive dysfunction. Neurotoxic effects of chemotherapeutic agents are common and include neuropathy, coagulopathy causing stroke or cerebral sinovenous thrombosis, encephalopathy, seizures, cerebellar dysfunction, myelopathy, and neuropsychologic difficulties. Hematopoietic stem cell transplant has a high risk of neurological complications including central nervous system infection, seizures, and stroke. Immunotherapies, including chimeric antigen receptor-modified T-cells (CAR T-cells) and immune checkpoint inhibitors, are emerging as potentially effective strategies to treat some types of childhood cancer, but may carry with them substantial neurotoxicity which is just beginning to be recognized and studied. With evolving treatment protocols, childhood cancer survivorship is increasing, and the role of the neurologist in managing both the acute and chronic neurological consequences of treatment is becoming more important. Prevention, early recognition, and treatment of therapy-associated neurotoxicity are imperative to ensuring children can remain on the most effective therapeutic regimens and to improve the neurological function and quality of life of childhood cancer survivors.

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.

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

Thromboembolism frequently occurs during acute lymphoblastic leukemia (ALL) therapy. We prospectively registered thromboembolic events during the treatment of 1772 consecutive Nordic/Baltic patients with ALL aged 1 to 45 years who were treated according to the Nordic Society of Pediatric Hematology and Oncology ALL2008 protocol (July 2008-April 2017). The 2.5-year cumulative incidence of thromboembolism (N = 137) was 7.9% (95% confidence interval [CI], 6.6-9.1); it was higher in patients aged at least 10 years (P < .0001). Adjusted hazard ratios (HRas) were associated with greater age (range, 10.0-17.9 years: HRa, 4.9 [95% CI, 3.1-7.8; P < .0001]; 18.0-45.9 years: HRa, 6.06 [95% CI, 3.65-10.1; P < .0001]) and mediastinal mass at ALL diagnosis (HRa, 2.1; 95% CI, 1.0-4.3; P = .04). In a multiple absolute risk regression model addressing 3 thromboembolism risk factors, age at least 10 years had the largest absolute risk ratio (RR_age, 4.7 [95% CI, 3.1-7.1]; RR_{enlarged lymph nodes}, 2.0 [95% CI, 1.2-3.1]; RR_{mediastinal mass}, 1.6 [95% CI, 1.0-2.6]). Patients aged 18.0 to 45.9 years had an increased hazard of pulmonary embolism (HRa, 11.6; 95% CI, 4.02-33.7; P < .0001), and patients aged 10.0 to 17.9 years had an increased hazard of cerebral sinus venous thrombosis (HRa, 3.3; 95% CI, 1.5-7.3; P = .003) compared with children younger than 10.0 years. Asparaginase was truncated in 38/128 patients with thromboembolism, whereas thromboembolism diagnosis was unassociated with increased hazard of relapse (P = .6). Five deaths were attributable to thromboembolism, and patients younger than 18.0 years with thromboembolism had increased hazard of dying compared with same-aged patients without thromboembolism (both P ≤ .01). In conclusion, patients aged at least 10 years could be candidates for preemptive antithrombotic prophylaxis. However, the predictive value of age 10 years or older, enlarged lymph nodes, and mediastinal mass remain to be validated in another cohort.