L-Asparaginase-induced coagulopathy during therapy of acute lymphocytic leukemia

Haemostatic alterations induced by treatment with asparaginases and clinical consequences

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

Hereditary and acquired defects in the fibrinolytic system associated with thrombosis

The fibrinolytic system plays a pivotal role in the regulation of hemostasis and the prevention of thrombosis. There are no drugs that will increase the plasma fibrinolytic activity for a lasting duration to prevent thrombotic events effectively. Despite the ability of vasoactive agents such as nicotinic acid and metformin to release PA from the vessel wall, this therapeutic effect has not been evaluated adequately. The PAs are short-acting and indicated only for thrombolysis and not for prophylaxis. Future directions are directed at finding, agents that can enhance plasminogen activator release or inhibit PAW-1 activity. As there are multiple factors involved in the pathogenesis of thrombosis, there are a number of conditions in which abnormal fibrinolysis is only a contributory factor. Examples are seen in pregnancy, especially during puerperium, when the thromboembolic risk is at its highest. The levels of inhibitors of fibrinolysis. both PAI-1 and PAI-2, are also at their highest. Another example was seen recently in the antiphospholipid syndrome, where antibodies against Annexin II, a receptor for tPA, were found to be higher than in healthy controls. Thus, a thorough investigation into other hereditary and acquired risk factors for thrombosis is recommended.

Thrombosis related to the use of L-asparaginase in adults with acute lymphoblastic leukemia: a need to consider coagulation monitoring and clotting factor replacement

L-asparaginase (L-asp) has become an important component of combination chemotherapy for acute lymphoblastic leukemia (ALL). However, L-asp can produce depletions in many of the clotting factors with an associated risk for thrombosis and hemorrhage. Three consecutive patients seen at the Mayo Clinic with L-asp related thrombosis are described and an in-depth review of the literature is provided. Two of the 3 patients developed central nervous system (CNS) complications with evidence of thrombosis and hemorrhagic infarction. Two of the patients also developed extensive upper extremity thrombosis. The results of comprehensive hemostatic surveys showed marked abnormalities in all 3 patients. Many of the thrombotic complications related to L-asp involve the CNS, as illustrated in 2 of our patients. These patients should be treated aggressively since full recovery is possible. The precise cause of thrombosis is yet to be determined but is likely multifactorial. The optimal treatment and prevention of thrombosis in this group of patients remains poorly defined.

Lack of pathogenetic role of proteins C and S in thrombosis associated with asparaginase-prednisone-vincristine therapy for leukaemia

Plasma levels of protein C and protein S antigens were measured in eight children who developed thrombosis following asparaginase-prednisone-vincristine treatment for acute lymphoblastic leukaemia and in nine similarly treated children without this complication. Protein C antigen levels were below normal in three of the eight patients with thrombosis and in three of the nine patients without the complication (P = 0.38). Low protein S antigen levels were found in five of six patients with thrombosis and in two of seven patients without thrombosis (P = 0.10). Plasma factor IX and factor X antigen levels, other vitamin K dependent factors, were also measured in the two groups of patients. In general, reduced levels of protein C, protein S or both antigens (anticoagulant vitamin K dependent proteins) were associated with reduced levels of factor IX, factor X, or both of these factors (procoagulant vitamin K dependent clotting proteins). The ratios of protein C and protein S antigens to each other and to factor IX and factor X antigens did not differ between the two groups. Thus, there is no clear evidence that reduced levels of protein C and (or) protein S cause thrombosis in leukaemia patients treated with this drug combination.

Problems of intensive therapy in childhood cancer

Tremendous progress has been made in the treatment of childhood cancers. Certain hematologic malignancies have an impressive cure rate with the current intensive antineoplastic treatment regimens. There is optimism that the treatment of children who have advanced stage solid tumors with intensive, multimodality therapy may improve their chances for long-term survival. These treatment programs, though potentially curative, are highly toxic, with severe myelosuppression and damage to other organ systems. An awareness of these potential toxicities, an understanding of how to prevent or minimize certain problems, and the ability to treat those complications which do arise are all essential to the successful management of childhood cancer.

Correction of hemostatic imbalances induced by L-asparaginase therapy in children with acute lymphoblastic leukemia

Thirteen children with ALL and L-asp-induced alterations of the coagulation system were treated with fresh-frozen plasma and antithrombin III (AT III) concentrate. Fresh-frozen plasma was given three times daily to maintain fibrinogen levels greater than 100 mg/dl. AT III concentrate was administered in a continuous infusion over 24 h as long as replacement with fresh-frozen plasma was given. When fibrinogen was greater than 100 mg/dl and AT III less than 80% of normal, only AT III concentrate was administered in a continuous infusion. In all patients treated with the replacement regimen described, fibrinogen levels were maintained greater than 100 mg/dl and AT III levels greater than 80%. No bleeding or thrombosis and no signs of disseminated intravascular coagulation were observed. Our study shows that correction of the alterations of the coagulation system induced by asparaginase can be achieved with a replacement regimen substituting both procoagulant material and the most important inhibitor of the coagulation system.

Thromboembolic complications associated with L-asparaginase therapy. Etiologic role of low antithrombin III and plasminogen levels and therapeutic correction by fresh frozen plasma

A case of an 18-year-old woman with acute lymphoblastic leukemia who developed L-asparaginase-associated stroke and subclavian vein thrombosis is presented. The latter was also associated with a Hickman central venous catheter. Thrombotic complications occurred when plasma levels of plasminogen and antithrombin III were still markedly reduced as a result of L-asparaginase therapy, although the fibrinogen had recovered from its lower levels. The stroke was treated with fresh frozen plasma and the subclavian vein thrombosis was treated with streptokinase and fresh frozen plasma. L-asparaginase and Hickman-associated coagulopathy is reviewed and the treatment is discussed.

Depression of functional and antigenic plasma antithrombin III (AT-III) due to therapy with L-asparaginase

Eleven patients with leukemia and lymphoma were treated with 14 courses of E. coli L-asparaginase. Abnormalities of the coagulation screening tests and decreased fibrinogen levels were observed in all patients during treatment. Significant depressions of functional (mean 32%) and antigenic (mean 48%) antithrombin III were observed by day 14 of therapy. There was no laboratory evidence of intravascular coagulation during 11/14 courses of L-asparaginase. Crossed immunoelectrophoresis of plasma obtained at the antithrombin nadir did not demonstrate an abnormal pattern which can be associated with an abnormal antithrombin III or an increase in antithrombin III-coagulation factor complexes. The major underlying mechanism of this depression is believed to be decreased hepatic synthesis, and the low levels of antithrombin III may be associated with an increased risk of thrombosis.

Intracranial bleeding during therapy with L-asparaginase in childhood acute lymphocytic leukemia

Two patients developed clinical features of intracranial bleeding--which were confirmed by computerized axial tomograms--during their induction therapy for acute lymphocytic leukemia. Coagulation studies showed clotting abnormalities including severe hypofibrinogenemia. These findings most probably were related to the effect of L-asparaginase which was part of the treatment protocol. Central nervous system leukemia, intrathecal chemotherapy, cranial irradiation, extreme leukocytosis, or thrombopenia at the time of diagnosis or day of stroke did not appear to be predisposing factors in these cases.

Intracranial hemorrhage and focal seizures secondary to use of L-asparaginase during induction therapy of acute lymphocytic leukemia

L-Asparaginase is commonly used for induction therapy of acute lymphocytic leukemia of childhood. Severe clinical bleeding secondary to clotting dysfunction has not been previously reported. We observed intracranial hemorrhagic infarcts with focal seizures and hemiparesis associated with clotting abnormalities, including severe hypofibrinogenemia, probably the result of L-asparaginase administered during induction therapy of acute lymphocytic leukemia.

Reduced antithrombin III levels during L-asparaginase therapy

Antithrombin III levels were measured in serum before, during, and after therapy with three different dosage regimens of L-asparaginase in 11 children with acute lymphoblastic leukemia. Levels determined by both functional and immunologic methods were transiently reduced during alternate-day or daily L-asparaginase treatment but not affected when the drug was administered only every 10 days. The probable mechanism of this effect is impaired hepatic synthesis of antithrombin III, resembling the acute and transient deficiency of other asparagine-rich proteins during L-asparaginase administration.