Acute Lymphoblastic Leukemia |
1 Hematology Departments of Angers
2 Nantes
3 Tours
4 Grenoble
5 Nancy
6 Rennes
7 Dijon
8 Saint Etienne
9 LFB-Paris, France
Correspondence: Yves Gruel, Service dHématologie Hémostase, Hôpital Trousseau, 37044 Tours Cedex, France. E-mail:gruel{at}med.univ-tours.fr
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Design and Methods: This was a retrospective analysis of 214 patients treated with L-asparaginase (7500 IU/m2 x 6) for acute lymphoblastic leukemia or lymphoblastic lymphoma. Between day 1 of the induction course and discharge, clinical events, and biological and therapeutic modifications were reviewed.
Results: Antithrombin and fibrinogen levels were lower than 60% and 1 g/L in 71% and 73% of patients, respectively. Twenty thromboses occurred in 9.3% of the patients; these patients had a median antithrombin level of 53% (range, 21–111) at the time of the event. Forty-two episodes of bleeding occurred in 31 patients with a median fibrinogen level of 1.3 g/L. Infusions of L-asparaginase were reduced or delayed in 64% of patients due to low fibrinogen and/or antithrombin levels. Fresh-frozen plasma, antithrombin and fibrinogen were infused in 31%, 41% and 52% of patients, respectively. The mean antithrombin and fibrinogen levels increased from 61% to 88% and from 1 to 1.4 g/L after infusion of antithrombin or fibrinogen respectively, while both levels remained unchanged after the infusion of fresh-frozen plasma. In patients who received antithrombin concentrates L-asparaginase injections were less frequently omitted or delayed (53% vs. 72%, p=0.005), the rate of thrombosis was lower (4.8% vs. 12.2%, p=0.04) and the disease-free survival was also reduced (p=0.05).
Conclusions: This retrospective study suggests that antithrombin concentrates may have a beneficial effect on the outcome of adults treated for acute lymphoblastic leukemia with L-asparaginase; prospective studies are essential to confirm this hypothesis.
Key words: L-asparaginase, acute lymphoblastic leukemia, antithrombin, fibrinogen.
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These hemostatic modifications induced by L-asparaginase are relatively rare and mild in children, but their incidence has not yet been well evaluated in adults. Moreover, the ways of preventing or treating these coagulation defects and their consequences are poorly defined. We, therefore, performed a multicenter retrospective study to address these issues, analyzing the data from 214 adult patients with ALL or T-lymphoblastic lymphoma (T-LBL) who had received induction therapy including six infusions of L-asparaginase.
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Chemotherapy regimen and supportive hemostatic treatment
Induction therapy was based on the BFM regimen8 and consisted of weekly intravenous administration of vincristine (2 mg/injection) and idarubicin (5 mg/m2/injection) on days 1, 8, 15, and 22 with six doses of intravenous Escherichia coli L-asparaginase (7500 IU/m2 on days 10, 13, 16, 19, 22 and 25) in addition to 3 weeks of daily steroids (40/mg/m2/day). The fourth injection of vincristine was replaced by teniposide (100 mg/m2) in cases of poor neurological tolerance. Erwiniase was used in cases of anaphylactic reaction (7500 IU/injection).
Blood-derived products, i.e. fresh-frozen plasma (FFP), Fg (Clottagen®, LFB, Les Ulis, France) and AT (Aclotine®, LFB) concentrates were recommended to maintain Fg and AT levels at >1 g/L and 60%, respectively. Alternatively, injections of L-asparaginase were delayed for 48 hours if no blood-derived products were administered. Platelets were transfused when counts were < 20x109/L and antithrombotic prophylaxis was prescribed in accordance with institutional guidelines. The most frequently applied protocol (in 75 patients) was based on the use of heparin (100 IU/kg/day) administered by intravenous infusion, which was stopped if the platelet count decreased below 20x109/L.
Clinical and laboratory parameters
Thrombotic or bleeding events occurring between the first injection of L-asparaginase and the patients discharge at the end of induction therapy were recorded. Hemoglobin (Hb) levels, white blood cell and platelet counts, Fg level (assessed by the von Clauss assay) and AT level (evaluated by a chromogenic assay), measured from diagnosis to the end of the induction regimen, were analyzed. The diagnosis of disseminated intravascular coagulation was based on the ISTH subcommittee criteria.9 To evaluate changes in AT and Fg levels after treatment with L-asparaginase, AT and Fg values measured before administration of any blood-derived product were analyzed. The efficacy of FFP, AT and Fg concentrates on plasma Fg and AT levels was evaluated by comparing values measured in the 24 hours before infusion of these blood-derived products to the values measured the following day.
Statistical analysis
Differences between groups were analyzed by the
2 test or Mann-Whitney U-test when appropriate. Odds ratios (OR) and confidence intervals (CI) were calculated with a logistic regression model. Overall survival and disease-free survival were analyzed by the Kaplan-Meier method, and differences in survival times were assessed by the log-rank test. SPSS software version 10.1.3 for Windows (SPSS Inc. Chicago, IL, USA) was used for these analyses.
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30x109/L and 7% had white cell counts
100x109/L. The median hemoglobin concentration was 97 g/L (range, 59–159), and the median platelet count was 62x109/L (range, 4–610). Disseminated intravascular coagulation was present in 7.5% of patients at diagnosis. None of the patients had a bleeding diathesis, while 5.6% and 8.4% of patients reported a personal or familial history of thrombosis, respectively. Combined oral contraceptives were stopped before initiation of induction therapy in all but 14 patients (4 with thrombosis and 10 without) and norpregnane derivatives (nomegestrol) were administered. Central venous access was used in all patients, but a port chamber was used in only three. One patient had previously been diagnosed as having hereditary protein S deficiency.
Treatment with L-asparaginase
Fifty-nine percent of patients received the six planned injections of Escherichia coli L-asparaginase, although injections were delayed at least once in 22% of cases. The number of injections of L-asparaginase was reduced in 41% of patients, to five (18%), four (8%), three (8%), two (5%) or one (2%) administrations. The most frequent explanation for withdrawal or delayed treatment with L-asparaginase was the presence of coagulation abnormalities, particularly Fg or AT deficiency (Table 1). In addition, five patients were treated with asparaginase from Erwinia because of allergic reactions.
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Table 1. Reasons for reducing the number of injections of L-asparaginase or delaying treatment.
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Figure 1. Changes in antithrombin levels during induction chemotherapy for acute lymphoblastic leukemia without any infusion of fresh-frozen plasma or antithrombin concentrates.
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Figure 2. Changes in fibrinogen levels during induction chemotherapy for acute lymphoblastic leukemia without any infusion of fresh-frozen plasma or fibrinogen concentrates.
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Figure 3. Changes in antithrombin (A) and fibrinogen levels (B) before and after infusion of blood-derived products.
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Table 2. Characteristics of the patients with and without thrombosis.
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AT levels were measured at the time of the event or in the days before thrombosis in 18 patients and were lower than 60% in 11 cases (61%) (median value 48%; range, 21–120). Importantly, the rate of thrombosis was lower in patients who had received AT concentrates (4/83, 4.8%) than in those who had not (16/131, 12.2%, OR 0.39; 95%CI 0.11–1.02; p=0.04). However, the rate of thrombosis was similar in patients who had or had not received prophylactic anticoagulation (6/85 vs. 14/127), FFP (5/67 vs. 15/147), or Fg concentrate (12/111 vs. 8/103).
Hemorrhagic events
Forty-two bleeding events occurred between 1 to 45 days (median, 8 days) after the first infusion of L-asparaginase in 31 patients (14.5%, CI 95% 9.8–19.2). These events were epistaxis (n=24), central venous access bleeding (n=8), rectorrhagia (n=1), large hematomas (n=8), and hemorrhagic stroke (in one patient who also had cerebral vein thrombosis). Bleeding events were diagnosed after a mean number of 2.4 infusions of L-asparaginase (range, 1–6). Apart from the hemorrhagic stroke, none of the bleeding events was considered to be severe, and platelets, FFP, Fg or AT concentrates were administered in only a few instances (for 7, 5, 8, and 1 events, respectively). The hemorrhagic events were not associated with a higher frequency of disseminated intravascular coagulation, more frequent use of unfractionated heparin or low molecular weight heparin (32% vs. 44% of patients without bleeding), higher number of infusions of L-asparaginase or difference in platelet count or Fg nadir (median 55 vs. 58x109/L, 0.9 vs. 0.8 g/L, respectively). In addition, AT, Fg concentrates and FFP were administered equally in patients with and without bleeding. The mean number of red blood cell units transfused was higher in patients with hemorrhagic events (4.3 vs. 2.1) although the difference was not statistically significant.
Relationship between acute lymphoblastic leukemia outcome, and thrombosis and hemorrhage
The general outcomes of the patients in this study and their prognostic factors have already been reported.6,7 The complete remission rate was similar in patients with and without thrombosis (Table 2). Despite none of the thrombotic events being fatal, the occurrence of thrombosis was associated with a reduced median overall survival (19 months vs. 53 months, p=0.06) and disease-free survival (14 months vs. 58 months, p=0.05) (Figure 4). This shorter survival time of patients with thrombosis was not related to any of the known prognostic factors for ALL, such as age, white cell count, or early achievement of complete response. Patients who had received five or six injections of L-asparaginase had a longer median overall survival (52 months vs. 31 months) and disease-free survival (70 months vs. 22 months) than those treated with four or fewer infusions, although the difference was not statistically significant. Finally, hemorrhagic events were not associated with any difference in patients survival.
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Figure 4. Kaplan-Meier survival curves in patients without and with thrombosis. (A) Overall survival (B) Disease-free survival.
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2-antiplasmin, with the lowest levels measured after the last infusion of L-asparaginase.14 Our study, involving a larger population of patients confirmed this reduction in AT and Fg levels. Fg initially decreased from day 1 to day 10 while corticosteroids were administered and despite the correction of disseminated intravascular coagulation, which was diagnosed in 7.5% of patients (a rate similar to that previously described).15 This decrease in plasma fibrinogen was then enhanced, reaching a median level of 1 g/L at the time of the fourth infusion of L-asparaginase. In addition, the median AT level decreased from 120% before administration of L-asparaginase to 59% at the time of the fourth infusion, with almost 50% of patients having AT levels below 60%. Despite the high frequencies of Fg and AT deficiency, the incidence of hemorrhagic and thromboembolic events was 14.5% and 9.3%, respectively. However, the use of retrospective records to evaluate the frequency of such events probably induced some bias in data collection and only clinically significant hemorrhages were recorded. Most of the hemorrhagic manifestations that occurred during induction therapy for ALL were mild, as previously reported.16 On the other hand, no increase in the incidence of bleeding was observed in patients with Fg levels lower than 0.5 g/L. However, FFP and Fg concentrates were frequently infused and this possibly reduced the risk of hemorrhage. FFP and Fg concentrates were administered to 31% and 52% of patients, respectively, but Fg levels increased only after infusion of Clottagen®. FFP induced no significant changes, but this can be explained by the fact that relatively small amounts of plasma, i.e. 5.4 mL/kg, were infused, whereas 20 mL/kg are usually necessary to increase Fg levels by at least 1g/L. FFP has previously been shown to improve coagulation abnormalities and to control bleeding in patients with ALL and disseminated intravascular coagulation.15 In contrast, no previous experience of the use of Fg concentrates has been reported in this particular clinical situation. Venous thrombosis is the most severe adverse event during induction therapy for ALL in patients receiving L-asparaginase, and such a complication occurred in 9.3% of patients in the CAPELAL cohort. The rate of thrombosis was lower in one large retrospective study (4.2%) involving 238 patients17 and in one recent meta-analysis (5.9%) including 323 adults patients18 but the use of relatively high doses of L-asparaginase in our patients might have in part contributed to these differences. The risk of thrombosis is presumably lower in children with ALL and was evaluated at 5.2% in a recent meta-analysis of 17 prospective studies comprising 1752 pediatric patients.19 Environmental risk factors for thrombosis are more frequent in adults than in children, but the only such factor clearly identified in our series was the use of oral contraceptives in women before induction. We did not, therefore, find any correlation between a very low Fg level (below 0.5 g/L) and thrombosis as previously reported,20 not did we confirm the increased incidence of thrombosis in ALL patients with a T-cell immunophenotype.21 Central venous catheters and genetic polymorphisms such as factor V Leiden and factor II 20210A have been associated with thrombosis in children,22,23 but we did not systematically look for these hereditary risk factors in our adult population. Acquired AT deficiency was frequently detected in patients with thrombosis (70%), but a similar defect was also present in patients without thrombosis. However, the rate of thrombosis was lower in patients who had received AT concentrates (4/88, 4.5%) than in those who had not (16/126, 12.7%, p=0.04). In addition, a significant increase in AT levels (from 60 to 88%, p<0.0001) was only achieved after infusion of Aclotine®. These findings therefore indicate that infusion of AT concentrates in patients with ALL treated with L-asparaginase may result in a significant clinical benefit in terms of preventing thrombosis.
The association between treatment with L-asparaginase, acquired AT deficiency and thrombosis has been found previously in several studies in which L-asparaginase was administered in induction or consolidation phase therapy.13,22–26 Several studies have also evaluated the potential benefit of AT concentrates in children and adults with ALL. Most measured surrogate markers evaluating thrombin generation27–30 and only one reported a lower incidence of thrombosis in patients treated with AT (0 events in 17 treated cases vs. 10 events in 37 patients not receiving AT, p=0.021).21 Although none of our patients died from thrombosis, overall and disease-free survival rates were decreased among the patients who had experienced a thrombotic event. We cannot exclude the possibility that the withdrawal of L-asparaginase because of coagulation abnormalities or thrombosis might have influenced the outcome of some patients. The fact that preventive administration of AT was associated with a lower rate of delayed treatment with L-asparaginase or a reduced number of injections, supports this hypothesis. Asparaginase was not administered in the other phases of treatment and we did not find any significant delay in the consolidation and maintenance therapy of patients with thrombosis.
CAPELAL is a retrospective study and the absence of stringent guidelines for the management of hemostasis abnormalities is, therefore, a significant limitation. Nonetheless, this study strongly suggests that replacement therapy with AT concentrates has a beneficial effect by decreasing the rate of thrombosis and improving overall survival in adult patients with ALL treated with L-asparaginase. Prospective studies are essential to confirm these findings.
MH, AM, NI and YG designed the research, PC, MD, CEB, SB, MB, IL, and JC included patients and revised the manuscript. MH and YG analyzed data and wrote the paper. AT, BP and NI revised the manuscript.
AT and BP are currently employees of LFB. MH, AM and YG have received consultation fees from the LFB. None of the other authors has any conflicts of interest to declare.
Received for publication February 21, 2008. Revision received June 10, 2008. Accepted for publication June 23, 2008.
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