Clinical significance of fibrinopeptide A in acute lymphocytic and non-lymphocytic leukaemia

Supranormal antithrombin III levels induced by concentrate administration are ineffective in quenching thrombin generation in acute promyelocytic leukemia

Coagulation abnormalities occurring in patients with acute promyelocytic leukemia (APL) are partially corrected by heparin administration. This study was undertaken to verify if "supra-normal" levels of antithrombin III (AT-III) are similarly able to quench intravascular thrombin generation triggered by APL cells. Eight patients with APL were randomly assigned to receive either 50 U/kg (Group A) or 100 U/kg (Group B) of an AT-III concentrate, starting on the first day of chemotherapy and continuing for 7 days thereafter. Fibrinopeptide A (FPA), prothrombin fragment F1+2 and thrombin-AT III complexes, measured before and 15 minutes after each AT-III infusion, decreased significantly after each infusion, but the effect was minimal and short-lived, despite the achievement of post-infusion levels of AT-III activity well above 150% (Group A) or 200% (Group B). Small amounts of heparin were consistently detected in AT-III concentrates and post-infusion plasma samples. The short-lived quenching of thrombin generation after AT-III concentrate could be partially explained by the infusion of heparin, rather than by supranormal AT-III levels.

Fibrinopeptide A changes during remission induction treatment with L-asparaginase in acute lymphoblastic leukemia: evidence for activation of blood coagulation

L-Asparaginase, a widely used antileukemic agent, inhibits liver protein synthesis leading to hypofibrinogenemia and hypoprothrombinemia together with a severe reduction of antithrombin III and protein C. An increased risk of thrombosis has been reported in leukemic patients treated with this agent. We measured fibrinopeptide A (FPA) changes in 14 patients with acute lymphoblastic leukemia during induction remission treatment with a protocol including L-Asparaginase (10,000 U/m2/daily intravenous for 14 days). At diagnosis, 9/14 patients had FPA level above upper limit of normal range (mean = 4.1 ng/ml). After two days of therapy, FPA rose to 5.2 ng/ml and thereafter showed a slight increase throughout. Antithrombin III, protein C and fibrinogen dropped to its nadir on day 6 and 9. However, the ratio FPA/fibrinogen on a molar basis showed a three-fold increase during this days, demonstrating that the thrombin-dependent consumption of fibrinogen was also increased. In conclusion, our data show that activation of blood coagulation occurs in concomitance with the hemostatic derangement caused by L-Asparaginase. Replacement therapy with the recently available antithrombin III concentrates may be worthy of a clinical trial to test its effectiveness in preventing the thrombotic phenomena reported in these patients.