Increased antithrombin III concentration in children with acute lymphatic leukaemia receiving L-asparaginase therapy

Five-year single-center study of asparaginase therapy within the ALL-BFM 2000 trial

BACKGROUND

Therapeutic drug monitoring (TDM) of asparaginase (ASNase), a fundamental element of acute lymphoblastic leukemia treatment, was integrated in the ALL-BFM 2000 protocol on a voluntary basis.

METHODS

Over a 5-year period, 127 patients (1,355 samples) were monitored for asparaginase activity in a single-center setting. We report monitoring data from throughout the ASNase containing treatment elements. Additional information obtained on risk stratification, minimal residual disease (MRD), steroid randomization and relapse is discussed in relation to ASNase activity.

RESULTS

At completion of the induction phase 93% (115/124) of patients showed sufficient ASNase activity (5,000 U/m(2) Escherichia coli ASNase), 77 of 86 (90%) monitored patients finished the first re-intensification element without requiring Erwinia ASNase. MRD, risk stratification and steroid randomization were not associated with significant differences in ASNase activity. Of patients who relapsed, only 25% (3/12) were able to maintain sufficient ASNase activity after E. coli ASNase.

CONCLUSION

This single-center data set gives a true and unbiased insight into clinical reality of ASNase therapy. It shows no significant relationship between MRD positivity or risk stratification and ASNase treatment intensity. Overall, within the ALL-BFM 2000 trial, 90% of patients completed first re-intensification without requiring third-line Erwinia ASNase.

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

Acute lymphoblastic leukaemia (ALL) is the most common malignancy associated with venous thromboembolism (VTE) in children. The prevalence of symptomatic VTE ranges from 0% to 36%, and the variation can be explained, at least in part, by differences in chemotherapeutic protocols. The mechanism for increased risk of VTE is associated with alterations in the haemostatic system by use of L-asparaginase (ASP) alone or in combination with vincristine or prednisone, presence of central venous lines (CVLs) and/or inherited thrombophilia. The children at greatest risk are generally those receiving Escherichia coli ASP concomitant with prednisone. The majority of symptomatic VTEs occur in the central nervous system or in the upper venous system. In the majority of cases, asymptomatic VTEs are associated with CVLs. External CVLs are affected more often than internal CVLs. Evidence-based guidelines on prevention and treatment guidelines for ALL-related VTE are lacking, and carefully designed clinical trials are needed urgently.

Thrombotic complications in childhood acute lymphoblastic leukemia: a meta-analysis of 17 prospective studies comprising 1752 pediatric patients

The risk of thrombosis in children with acute lymphoblastic leukemia (ALL) reportedly ranges between 1% and 37%. Epidemiologic studies have usually been hampered by small numbers, making accurate estimates of thrombosis risk in ALL patients very difficult. The aim of this study was to better estimate the frequency of this complication and to define how the disease, its treatment, and the host contribute to its occurrence. We made an attempt to combine and analyze all published data on the association between pediatric ALL and thrombosis, by using a meta-analytic method. The rate of thrombosis in 1752 children from 17 prospective studies was 5.2% (95% CI: 4.2-6.4). The risk varies depending on several factors. Most of the events occurred during the induction phase of therapy. Lower doses of asparaginase (ASP) for long periods were associated with the highest incidence of thrombosis, as were anthracyclines and prednisone (instead of dexamethasone). The presence of central lines and of thrombophilic genetic abnormalities also appeared to be frequently associated with thrombosis. In conclusion, the overall thrombotic risk in ALL children was significant, and the subgroup analysis was able to identify high-risk individuals, a finding that will hopefully guide future prospective studies aimed at decreasing this risk.

Thrombosis in children with acute lymphoblastic leukemia

At diagnosis, there is evidence of increased thrombin generation in children with acute lymphoblastic leukemia (ALL), the etiology of which is unclear. However, thromboembolism (TE) in children with ALL is most commonly reported after the initiation of antileukemic therapy indicating a possible interaction of the disease and therapy. Antileukemic therapy influences the haemostatic system either by direct effect of the chemotherapeutic agents or indirectly through the effect of supportive care, e.g. central venous line (CVL) or infectious complications secondary to immunosuppression. Asparaginase and steroids are shown to induce hypercoagulable state by suppression of natural anticoagulants, especially AT and plasminogen, and by elevations in F VIII/vWF complex, respectively. In addition, steroid therapy causes hypofibrinolytic state by dose-dependent increase in plasminogen activator inhibitor 1 (PAI-1) levels. Combination of these effects coupled with increased thrombin generation may be responsible for the increased incidence of TE observed with concomitant administration of asparaginase and steroids. Further studies to delineate the mechanism of increased thrombin in generation children with ALL and effects of various chemotherapeutic agents, in isolation and in combination, on haemostatic system are needed.

Analytical validation of a microplate reader-based method for the therapeutic drug monitoring of L-asparaginase in human serum

The enzyme L-asparaginase (ASNASE), which hydrolyzes L-asparagine (L-Asn) to ammonia and L-aspartic acid (L-Asp), is commonly used for remission induction in acute lymphoblastic leukemia. To correlate ASNASE activity with L-Asn reduction in human serum, sensitive methods for the determination of ASNASE activity are required. Using L-aspartic beta-hydroxamate (AHA) as substrate we developed a sensitive plate reader-based method for the quantification of ASNASE derived from Escherichia coli and Erwinia chrysanthemi and of pegylated E. coli ASNASE in human serum. ASNASE hydrolyzed AHA to L-Asp and hydroxylamine, which was determined at 710 nm after condensation with 8-hydroxyquinoline and oxidation to indooxine. Measuring the indooxine formation allowed the detection of 2 x 10(-5)U ASNASE in 20 microl serum. Linearity was observed within 2.5-75 and 75-1,250 U/L with coefficients of correlation of r(2)>0.99. The coefficients of variation for intra- and interday variability for the three different ASNASE enzymes were 1.98 to 8.77 and 1.73 to 11.0%. The overall recovery was 101+/-9.92%. The coefficient of correlation for dilution linearity was determined as r(2)=0.986 for dilutions up to 1:20. This method combined with sensitive methods for the quantification of L-Asn will allow bioequivalence studies and individualized therapeutic drug monitoring of different ASNASE preparations.

Thrombotic events revisited in children with acute lymphoblastic leukemia: impact of concomitant Escherichia coli asparaginase/prednisone administration

Recently published data suggest that the prothrombin G20210A variant, the TT677 methylenetetrahydrofolate reductase genotype, the factor V G1691A mutation, deficiencies of protein C, protein S, antithrombin, and elevated lipoprotein (a) concentrations were associated with venous thromboembolism in childhood patients treated according to the BFM protocol. To unravel the role of these prothrombotic risk factors and different treatment modalities, the present comparative study was performed in childhood leukemia patients of the same living population. Four hundred and twenty consecutively recruited leukemic children (BFM n=300; COALL n=120) were enrolled in this study with respect to the presence of prothrombotic risk factors and the occurrence of symptomatic venous thrombosis. No significant difference was found in the prevalence rates of thrombotic risk factors in the Caucasian populations studied. Symptomatic venous thromboembolism occurred in 11.6% of BFM patients compared with 2.5% in the COALL treatment group [odds ratio (OR)/95% confidence intervals (CI): 7.7/1.8-32.6; P=.005]. Including age, prothrombotic risk factors, central venous lines, treatment protocols, and anti-leukemic drugs in a logistic regression model, only the concomitant Escherichia coli asparaginase/prednisone administration in leukemic children suffering from a prothrombotic risk factor was found to increase the rate of thrombotic manifestations during leukemia treatment in patients of the same Caucasian origin (OR/95% CI: 34.5/4.39-271.42; P=.0008). Based on the data presented here, we suggest the use of prednisone and E. coli asparaginase concomitantly administered in a leukemic patient suffering from a prothrombotic risk factor to be responsible for the onset of venous thrombosis in the majority of cases.

Effect of protracted high-dose L-asparaginase given as a second exposure in a Berlin-Frankfurt-Münster-based treatment: results of the randomized 9102 intermediate-risk childhood acute lymphoblastic leukemia study--a report from the Associazione Italiana Ematologia Oncologia Pediatrica

PURPOSE

To assess in a randomized study the therapeutic effect of the addition of high-dose L-asparaginase (HD ASP) in the context of a Berlin-Frankfurt-Münster (BFM)-based chemotherapy regimen for intermediate risk (IR) childhood acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

From March 1991 to April 1995, a total of 705 patients, with 59% of the cohort of patients fewer than 15 years old, with newly diagnosed non-B ALL, enrolled onto the Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) ALL-91 study, were assigned to the IR group. Patients in remission at the beginning of the reinduction phase were randomized either to the standard treatment (SD ASP arm) or the experimental treatment (HD ASP arm; weekly intramuscular administration of HD ASP 25,000 IU/m(2) repeated for a total of 20 weeks). Most of the patients (90%) were treated with Erwinia chrysanthemi L-asparaginase product.

RESULTS

Among the 610 patients randomized to the SD ASP arm (n = 322) or to the HD ASP arm (n = 288), relapse occurred at a median time of 24 months after randomization in 76 (24%) and in 64 children (22%), respectively. Most of the relapses occurred in the marrow (100 isolated, 21 combined). There was no significant difference between the disease-free survival in the two treatment arms (P =.64), with estimated values at 7 years from randomization of 72.4% (SE 3.1) v 75.7% (SE 2.6) in the SD ASP and HD ASP arms, respectively.

CONCLUSION

No advantage was observed for IR ALL children treated with BFM-based intensive chemotherapy who received protracted E chrysanthemi HD ASP during reinduction and the early continuation phase.

Minimal effects of E. coli and Erwinia asparaginase on the coagulation system in childhood acute lymphoblastic leukemia: a randomized study

A randomized study was done in twenty newly diagnosed children with acute lymphoblastic leukemia. Ten children were treated with Escherichia coli L-asparaginase, and ten with Erwinia chrysanthemi L-asparaginase. L-asparaginase (ASP) treatment started halfway during ALL-induction treatment with vincristine, prednisone, daunorubicin and intrathecal methotrexate. The mean activated partial thromboplastin time (APTT) level in all children demonstrated a significant fall (P < 0.001) from 28.25 sec at diagnosis to 23.0 sec at the start of ASP treatment. In this same time interval, the mean fibrinogen level declined markedly from 3 g/l to 1.2 g/l (P < 0.001), probably due to prednisone therapy. The APTT stayed shortened during ASP therapy, whereas the hypofibrinogenemia recovered significantly faster in the Erwinia group (P < or = 0.01). Factors (F) II, V, VII and X stayed within the normal range, while F VIII and F IX were elevated. During the entire period of induction therapy, the ATIII activity remained within the normal range in both treatment groups. The protein C values, however, demonstrated a steady decline from 140% at start of ASP treatment to a mean of 81% and 93%, respectively, at the end of the ASP therapy in the E. coli and Erwinia group. Five of the ten children treated with E. coli ASP demonstrated protein C levels below 70% at the end of ASP therapy, opposed to none of the Erwinia treated patients (P = 0.03). We suggest that the effect of ASP resulting in decreased coagulation factor synthesis is in part counterbalanced by the effect of prednisone on the coagulation system, when ASP is administered at the end of ALL induction treatment. The overall effect of ASP either of E. coli or of Erwinia on the hemorrhagic system reveals a slight imbalance towards thrombosis, mainly because of a gradual decrease in protein C activity. This imbalance is less pronounced in the Erwinia group.

Surgical complications in acute leukemia in childhood: a 20 year experience

A retrospective study of all patients presenting with acute leukemia to a single institution during the period 1968-1988 was undertaken to determine the type and incidence of surgical complications. One hundred twenty-eight of 296 patients were identified as requiring a surgical consultation for complications occurring during the course of the disease and many surgical disciplines were involved. Operative intervention was often required for these complications. Pediatric surgical specialists need to be aware of the range of surgical complications that can occur in children with acute leukemia and they must work in close co-operation with pediatric medical oncologists to ensure optimal treatment for all patients.

Non-randomised study comparing toxicity of Escherichia coli and Erwinia asparaginase in children with leukaemia

Seven hundred fifty-eight unselected children entered into the United Kingdom Medical Research Council acute lymphoblastic leukaemia UKALL VIII Study and Trial were studied for differences in early treatment-related toxicity according to the type of intramuscular L-asparaginase received. Two hundred seventy-five received a product obtained from Escherichia coli and 483 the enzyme from Erwinia chrysanthemi. The E. coli patients had a significantly higher incidence of neurotoxicity, pancreatitis, and life-threatening sepsis (4%, 2%, and 20%, respectively) when compared with the Erwinia group (2%, 0%, and 18%). Severe hypersensitivity was seen in one patient from both groups and the incidence of glucose intolerance was not significantly different. These findings indicate that E. coli asparaginase may be more toxic. With a minimum follow up of 4 1/2 years there is no evidence that either product has made a significantly different contribution to disease-free survival.

Recent experience with intensive combination chemotherapy for treatment of childhood acute lymphoblastic leukaemia

Forty-eight children with acute lymphoblastic leukaemia (ALL) who presented to the Oncology Department of Our Lady's Hospital for Sick Children, Crumlin, Dublin over a 52 month period were treated using a schedule modified from the BFM-81 protocol. All patients achieved remission within four weeks. With a minimum follow up period of 18 months, actuarial disease free survival was 68% and overall survival 75%. Mean hospital stay throughout the treatment period was 31 days. While these results represent an improvement in overall survival compared with historical controls, careful selection of risk categories will be the major aim of future studies so that more appropriate treatment can be instituted for high risk patients while minimising therapy for low risk disease.