The effect of L-asparaginase on antithrombin, plasminogen, and plasma coagulation during therapy for acute lymphoblastic leukemia.

Hemostatic function was studied sequentially in 12 children receiving L-asparaginase, vincristine, and prednisone as remission induction chemotherapy for acute lymphoblastic leukemia. The three-week period of L-asparaginase therapy was characterized by progressive decreases in plasma antithrombin, plasminogen, and fibrinogen concentrations, and by progressive increases in plasma clotting times (prothrombin time, partial thromboplastin time, thrombin time). Platelet counts rose rapidly during the third and fourth weeks of therapy as bone marrow remission was achieved. Factor V levels increased steadily during a five-week period, perhaps related to vincristine or prednisone therapy. Recent reports of thrombosis and hemorrhage in children and adults receiving L-asparaginase may be explained by this complex set of abnormalities in coagulation and coagulation control.