Recombinant activated factor VII for severe gastrointestinal bleeding after chemotherapy in an infant with acute megakaryoblastic leukemia

Understanding the therapeutic action of recombinant factor VIIa in platelet disorders

Recombinant factor VIIa (rFVIIa) is a pro-haemostatic agent that is effective in the treatment of bleeding in haemophilia complicated by inhibitors and some other haemorrhagic disorders. The rFVIIa product promotes haemostasis in these settings by enabling the rapid generation of thrombin on the surface of activated platelets which increases fibrin deposition. rFVIIa also has therapeutic activity in bleeding in platelet function disorders such as Glanzmann's thrombasthenia and thrombocytopenia. This suggests that rFVIIa also has a pro-haemostatic effect on platelets and this may contribute to the overall therapeutic action of this agent. The effects of high-concentration FVIIa on platelets have been studied in detail in experiments using ex vivo model systems of haemostasis under static and flow conditions. These experiments show that FVIIa potentiates multiple functional markers of platelet activation and this effect requires direct binding of FVIIa to the activated platelet membrane and the generation of thrombin. The mechanism of this potentiating effect of FVIIa on platelet activation is complex and is likely to require multiple platelet activation receptors and signalling pathways. These include the GPIb-IX-V glycoprotein complex and the thrombin protease activated receptors. The proposed mechanism of action of high-concentration FVIIa has important implications for the therapeutic activity of rFVIIa in vivo. This review summarizes the clinical and experimental evidence supporting a potentiating effect of FVIIa on platelet activation and discusses the likely mechanism of action.

The Evidence for the Use of Recombinant Human Activated Factor VII in the Treatment of Bleeding Patients With Quantitative and Qualitative Platelet Disorders

There are increasing reports suggesting that high-dose recombinant human activated factor VII (rFVIIa) is effective in the treatment and prevention of bleeding in patients with quantitative and qualitative platelet disorders. These clinical observations are supported by evidence that FVIIa binds weakly to activated platelet surface and at high concentration improves thrombin generation. In experimental models, this improved thrombin generation enhances platelet adhesion in thrombocytopenic conditions and enhances adhesion and aggregation of platelets lacking glycoprotein IIbIIIa (integrin alpha(IIb)beta(3)), characteristic of the qualitative platelet disorder Glanzmann thrombasthenia (GT). There is a need for clinical trials to confirm the safety and efficacy of rFVIIa in patients with various quantitative and qualitative platelet defects, either by itself or in combination with other hemostatic agents such as platelet transfusion. Pending the availability of such data, rFVIIa may be considered in severe bleeding in thrombocytopenia and GT patients with platelet antibodies and refractory to platelet transfusions and other standard treatments. An international survey suggests that rFVIIa at about 90 microg/kg every 2 hours for 3 or more doses could be used for GT patients with severe bleeding, but confirmation by larger studies is needed. For GT patients undergoing surgery and for treatment and prevention of bleeding in thrombocytopenic patients, the optimal rFVIIa regimen remains to be defined.

The potential role of recombinant activated FVII in the management of critical hemato-oncological bleeding: a systematic review

Recombinant activated factor VII (rFVIIa) is an hemostatic agent that was originally developed for the treatment of hemorrhage in patients with hemophilia and inhibitors. However, in the last few years rFVIIa has been employed with success in a broad spectrum of congenital and acquired bleeding conditions. In this systematic review we present the current knowledge on the use of this drug in patients suffering from hemato-oncological disorders, which are quite commonly complicated by severe hemorrhage. On the whole, data in the literature suggest a potential role for rFVIIa in the management of bleeding unresponsive to standard therapy in patients with hematological malignancies, including those undergoing bone marrow transplant. However, the vast majority of the currently available data are derived from uncontrolled studies including single cases or small series of patients. Thus, further trials with larger numbers of patients are needed to establish the most appropriate doses and timing of rFVIIa and to assess its efficacy and safety in this setting.

Recombinant activated factor VII for severe uterine bleeding after chemotherapy in a woman with acute myeloid leukemia

Acute hemorrhage is sometimes a serious complication that may arise in patients with acute leukemia as a result of therapy-induced myelosuppression. In most cases, transfusion of platelets and red blood cells are used to manage this clinical entity. These therapeutic interventions are not always successful and a more direct approach to activating the coagulation system can be more effective and, in some instances, life saving. Recombinant activated factor VII (rFVIIa), which is used for management of hemophiliac patients with inhibitors, is a major alternative in such situations. Here we describe the use of rFVIIa in a 41-year-old patient with ongoing vaginal bleeding with acute myeloid leukemia. Our experience indicates that rFVIIa may be an effective salvage treatment in bleeding conditions related to leukemia.