Recombinant factor VIIa in the treatment of bleeding in hemophilic children with inhibitors

Response to treatment and adverse events associated with use of recombinant activated factor VII in children: a retrospective cohort study

BACKGROUND

Recombinant activated factor VII (rFVIIa) is United States (US) Food and Drug Administration (FDA)-approved for patients with hemophilia with inhibitors or congenital factor VII deficiency. Initial reports of off-label use highlighted its efficacy, though newer reports have not repeated these findings. In both types of publication, though, secondary thromboses have been seen in adult patients. The data in children are less clear.

METHODS

This study analyzed all rFVIIa use at a large children's hospital for characteristics and outcomes. Recipients of rFVIIa were identified retrospectively via the electronic medical record. Data on patient diagnosis, lab data, other treatments, adverse events, and outcomes were collected.

RESULTS

Over 33 months, 66 patient episodes were treated with a total of 606 doses (median = 2). The most common indication (36.4%) was gastrointestinal bleeding (24/66 patients). Only one patient received a dose for an approved labeled indication. For control of bleeding, 33.3% of courses were unsuccessful (19/57). Bleeding from multiple sites was associated with treatment failure. In 16.7% of patients (11/66), unexpected adverse thromboses developed within 1 week of completing a course of rFVIIa. Thromboses in both intra- and extra-corporeal sites were included if they compromised patient care.

CONCLUSIONS

In the majority of cases reviewed, rFVIIa was successful in stopping or slowing serious bleeding episodes. It was least effective when a patient had diffuse bleeding at the time of administration. The thrombosis rate of 16.7% was higher than expected, though causality cannot be declared. Further investigation is needed to determine the risk-benefit ratio in children.

Safety and efficacy of recombinant factor VIIa by pediatric age cohort: reassessment of compassionate use and trial data supporting US label

BACKGROUND

The relative safety and efficacy of recombinant activated coagulation factor VII (rFVIIa, NovoSeven® RT) across pediatric age cohorts is poorly defined. The objective of this analysis was to assess the safety and efficacy of rFVIIa in pediatric patients with congenital hemophilia with inhibitors (CHwI) in the clinical studies supporting the U.S. labeling.

PROCEDURE

Pediatric data were derived from seven studies (five acute and two perioperative treatments) and pooled. All data were stratified by age (<2, 2 to <6, 6 to <12, and 12-16 years) and study category (acute treatment of bleeding episodes or surgery).

RESULTS

The pediatric dataset included 172 patients; 144 received rFVIIa for the treatment of bleeding episodes and 28 for the control of bleeding perioperatively. Recombinant FVIIa was effective for 95.4% (1,026/1,076) of the evaluable bleeding episodes and had similar treatment effectiveness across pediatric age groups (range, 94.1-97.2%). The majority received doses of 90 mcg/kg. rFVIIa was effective in achieving perioperative hemostasis across pediatric age groups (range, 91-100%), with greater efficacy observed with the recommended (90 mcg/kg) versus lower dose (35 mcg/kg). A total of 88 pediatric patients experienced a total of 285 adverse drug reactions, similar in type to those reported among adult patients. A total of seven thrombotic events were recorded in seven pediatric patients; only one was confirmed related to rFVIIa upon individual case review.

CONCLUSIONS

rFVIIa is safe and effective in the treatment of bleeding episodes and prevention of periprocedure bleeding in CHwI with no apparent differences observed among pediatric age groups.

Human recombinant factor VIIa may improve heat intolerance in mice by attenuating hypothalamic neuronal apoptosis and damage

Intolerance to heat exposure is believed to be associated with hypothalamo-pituitary-adrenocortical (HPA) axis impairment [reflected by decreases in blood concentrations of both adrenocorticotrophic-hormone (ACTH) and corticosterone]. The purpose of this study was to determine the effect of human recombinant factor VIIa (rfVIIa) on heat intolerance, HPA axis impairment, and hypothalamic inflammation, ischemic and oxidative damage, and apoptosis in mice under heat stress. Immediately after heat stress (41.2 °C for 1 h), mice were treated with vehicle (1 mL/kg of body weight) or rfVIIa (65-270 µg/kg of body weight) and then returned to room temperature (26 °C). Mice still alive on day 4 of heat exposure were considered survivors. Cellular ischemia markers (e.g., glutamate, lactate-to-pyruvate ratio), oxidative damage markers (e.g., nitric oxide metabolite, hydroxyl radials), and pro-inflammatory cytokines (e.g., interleukin-6, interleukin-1β, tumor necrosis factor-α) in hypothalamus were determined. In addition, blood concentrations of both ACTH and corticosterone were measured. Hypothalamic cell damage was assessed by determing the neuronal damage scores, whereas the hypothalamic cell apoptosis was determined by assessing the numbers of cells stained with terminal deoxynucleotidyl transferase-mediated αUTP nick-end labeling, caspase-3-positive cells, and platelet endothelial cell adhesion molecula-1-positive cells in hypothalamus. Compared with vehicle-treated heated mice, rfVIIa-treated heated mice had significantly higher fractional survival (8/10 vs 1/10), lesser thermoregulatory deficit (34.1 vs 24.8 °C), lesser extents of ischemic, oxidative, and inflammatory markers in hypothalamus, lesser neuronal damage scores and apoptosis in hypothalamus, and lesser HPA axis impairment. Human recombinant factor VIIa appears to exert a protective effect against heatstroke by attenuating hypothalamic cell apoptosis (due to ischemic, inflammatory, and oxidative damage) in mice.

Off-label use of recombinant factor VIIa in pediatric patients

OBJECTIVE

To examine off-label recombinant factor VIIa (rFVIIa) use in pediatric patients including clinical indications, dose, adverse events, and outcomes.

METHODS

All pediatric patients entered into the Haemostasis Registry from 75 participating hospitals were analyzed.

RESULTS

Three hundred and eighty-eight pediatric patients received off-label rFVIIa from 2003 to 2009. Median age was 12 months (interquartile range 1 month to 11 years). Clinical context included cardiac surgery (52.1%), medical (11.6%), other surgery (10.8%), hematology/oncology (10.3%), trauma (9.3%), intracranial hemorrhage (3.1%), and liver disease (2.8%). Twenty-six patients received extracorporeal membrane oxygenation at the time of rFVIIa administration. Median first dose was 114 μg/kg (interquartile range 90-181; range 7-2250). Thirty-four percent received >1 dose. There was a reduction in usage of red blood cells, platelets, fresh-frozen plasma, and cryoprecipitate in the 24 hours after the first dose for all patients (all P values < .001). Thromboembolic adverse events (TEAs) were reported in 5.4%. No association between TEA and size of first dose was found. Where data were available, 82% of patients were subjectively classified as responding to rFVIIa. Overall 28-day mortality was 27%. In multivariate analysis, pH values before administration and clinical context were independently associated with response to first dose and 28-day mortality.

CONCLUSIONS

There was a significant reduction in blood product administration after rFVIIa and a subjective response rate of 82%. Both pH and clinical context were associated with response to rFVIIa and mortality. Overall, 5.4% had a TEA reported.

Recombinant activated factor VII for hemorrhage after pediatric cardiac surgery

Postoperative bleeding is a common complication after pediatric cardiac surgery. Use of recombinant activated factor VII for intractable hemorrhage after cardiac, pediatric, and neurosurgery has been shown to decrease postoperative bleeding, but data in children are limited. This retrospective study analyzed 20 children <15 years-old who underwent cardiac surgery and received recombinant activated factor VII for refractory postoperative hemorrhage. All patients underwent mediastinal reexploration before recombinant activated factor VII was administered as a bolus dose over 2–3 min as rescue therapy. If no significant decrease in chest tube drainage was observed, the dose was repeated after an interval of at least 2 h. The median dose of recombinant activated factor VII administered per bleeding episode was 83.33 µg·kg−1 (range, 72.47–87.50 µg·kg−1), and the dose per patient was 154.16 µg·kg−1 (range, 93.06–180.52 µg·kg−1). The median number of doses found to be effective in these children was 1.76. There were significant decreases in mediastinal chest tube drainage and the volume of packed red blood cells, platelet concentrates, and cryoprecipitate administered after recombinant activated factor VII. No complications were observed during the therapy.

Ensembles of uncertain mathematical models can identify network response to therapeutic interventions

The role of mechanistic modeling and systems biology in molecular medicine remains unclear. In this study, we explored whether uncertain models could be used to understand how a network responds to a therapeutic intervention. As a proof of concept, we modeled and analyzed the response of the human coagulation cascade to recombinant factor VIIa (rFVIIa) and prothrombin (fII) addition in normal and hemophilic plasma. An ensemble of parametrically uncertain human coagulation models was developed (N = 437). Each model described the time evolution of 193 proteins and protein complexes interconnected by 301 interactions under quiescent flow. The 467 unknown model parameters were estimated, using multiobjective optimization, from published in vitro coagulation studies. The model ensemble was validated using published in vitro thrombin measurements and thrombin measurements taken from coronary artery disease patients. Sensitivity analysis was then used to rank-order the importance of model parameters as a function of experimental or physiological conditions. A novel strategy for the systematic comparison of ranks identified a family of fX/FXa and fII/FIIa interactions that became more sensitive with decreasing fVIII/fIX. The fragility of these interactions was preserved following the addition of exogenous rFVIIa and fII. This suggested that exogenous rFVIIa did not alter the qualitative operation of the cascade. Rather, exogenous rFVIIa and fII took advantage of existing fluid and interfacial fX/FXa and fII/FIIa sensitivity to restore normal coagulation in low fVIII/fIX conditions. The proposed rFVIIa mechanism of action was consistent with experimental literature not used in model training. Thus, we demonstrated that an ensemble of uncertain models could unravel key facets of the mechanism of action of a focused intervention. Whereas the current study was limited to coagulation, perhaps the general strategy used could be extended to other molecular networks relevant to human health.

Defining the role of recombinant activated factor VII in pediatric cardiac surgery: where should we go from here?

OBJECTIVES

Postoperative hemorrhage is a recognized complication of pediatric cardiac surgery. Both the immature coagulation system and increased susceptibility to hemodilution increase the likelihood of pediatric patients developing coagulopathy when compared with adult counterparts. Treatment options remain limited. Recombinant factor VII (rFVIIa) is a hemostatic agent increasingly used to reduce hemorrhage in other surgical settings, the role of which is unclear in this population. This article systematically reviews the published literature on the use of rFVIIa in pediatric cardiac surgery.

DATA SOURCES AND STUDY SELECTION

A systematic literature search identified reports of rFVIIa administration in pediatric patients undergoing cardiac surgery. Where possible, individual patient-specific data were extracted and pooled statistical analysis was performed.

DATA EXTRACTION AND SYNTHESIS

Twenty-nine articles reporting on the administration of rFVIIa to 169 patients were identified. rFVIIa has been administered to patients with predefined congenital abnormalities of hemostasis to arrest hemorrhage refractory to other interventions and prophylactically in the hope of reducing blood loss. Treatment regimens vary widely, in terms of both first and cumulative dose. Data on chest tube blood loss and two markers of coagulation were pooled and analyzed, and significant improvements were demonstrated. Mortality was 4.4% for the entire cohort but 20% of patients on extracorporeal membrane oxygenation suffered significant thromboembolic complications.

CONCLUSIONS

rFVIIa has an increasingly accepted role in the management of patients with congenital coagulopathies undergoing major surgery. However, randomized trials are required to define the role of rFVIIa as an adjunct to control major hemorrhage in the pediatric cardiac surgical population. Any future work must focus not only on benefits but also on patient safety, particularly, risk of morbid thromboembolic complication.

Long-term expression of murine activated factor VII is safe, but elevated levels cause premature mortality

Intravenous infusion of recombinant human activated Factor VII (FVIIa) has been used for over a decade in the successful management of bleeding episodes in patients with inhibitory antibodies to Factor VIII or Factor IX. Previously, we showed that expression of murine FVIIa (mFVIIa) from an adeno-associated viral (AAV) vector corrected abnormal hemostatic parameters in hemophilia B mice. To pursue this as a therapeutic approach, we sought to define safe and effective levels of FVIIa for continuous expression. In mice transgenic for mFVIIa or injected with AAV-mFVIIa, we analyzed survival, expression levels, in vitro and in vivo coagulation tests, and histopathology for up to 16 months after birth/mFVIIa expression. We found that continuous expression of mFVIIa at levels at or below 1.5 microg/ml was safe, effective, and compatible with a normal lifespan. However, expression levels of 2 microg/ml or higher were associated with thrombosis and early mortality, with pathologic findings in the heart and lungs that were rescued in a low-factor X (low-FX) mouse background, suggesting a FX-mediated effect. The findings from these mouse models of continuous FVIIa expression have implications for the development of a safe gene transfer approach for hemophilia and are consistent with the possibility of thromboembolic risk of continuously elevated FVIIa levels.

Applicability and safety of recombinant activated factor VII to control non-haemophilic haemorrhage: investigational experience in 265 children

Experience of recombinant activated factor VII (rFVIIa, NovoSeven; Novo Nordisk A/S, Bagsvaerd, Denmark) to control haemorrhage in non-haemophilic children is limited. The object of this study was to examine the applicability and safety of rFVIIa amongst a group of non-haemophilic paediatric subjects. Details of all non-haemophilic children < or =16 years receiving rFVIIa whose data were recorded in the investigational, internet-based registry, haemostasis.com were analysed. A total of 265 children (mean age 7.7 years) were treated with rFVIIa; the median dose administered was 78.4 microg kg(-1) body weight (range 9.0-393.4) and the median total dose received 100.0 microg kg(-1) body weight (range 10.9-1341.2). Therapeutic areas included surgery (34.5%), coagulopathy (including thrombocytopenia; 29.0%), spontaneous bleeding (17.2%), trauma (8.4%) and intracranial haemorrhage (4.5%). Two patients experienced thromboembolic events following administration of rFVIIa. Thirty-nine patients died on account of haemorrhage or complications relating to their underlying condition; neither the thromboembolic events nor the deaths were related to rFVIIa administration. Bleeding stopped in 118/237 (49.8%), markedly decreased in 54/237 (22.8%), decreased in 51/237 (21.5%), remained unchanged in 13/237 (5.5%) and increased in 1/237 (0.4%) patients. These results suggest that rFVIIa is safe and widely applicable in children to control non-haemophilic haemorrhage.

Evidence-based use of recombinant FVIIa (NovoSeven, NiaStase) for the treatment of hemophilia with inhibitors in children and adolescents

Children and adolescents comprise a significant proportion of the hemophilia population, including those patients who have developed inhibitors to factor VIII or FIX. We examine the use of rFVIIa for the treatment of bleeding episodes and the prevention of bleeding in children and adolescents with hemophilia A and B with inhibitors, focusing on registry data and recent clinical trial results. Based on this review of the literature, we conclude that recombinant FVIIa is safe and effective for use in controlling bleeding in these patient populations.

An overview of the history, clinical practice concerns, comparative studies and strategies to optimize therapy of bypassing agents

Despite significant advances in the treatment of haemophilia, including availability of recombinant coagulation factor replacement products and the use of prophylactic infusion regimens, the segment of haemophilic patients who develop inhibitory antibodies remain at higher risk for morbidity and mortality associated with recurrent or uncontrolled bleeding events. Bypassing agents represent the mainstay of treatment and prevention of bleeding. The most commonly used of the currently available therapeutic agents are a plasma-based therapy, factor eight inhibitor bypassing activity, vapour heated, and a recombinant therapy, NovoSeven (recombinant activated factor VIIa). A substantial body of literature exists to document efficacy and adverse event profiles for these two products. There is, however, a paucity of data arising from adequately powered prospective trials to determine optimal treatment and dosing in various clinical situations. Certain clinical circumstances, patient profiles, individual responses, or provider predilection may lead to preferential use of one of these products over the other; however, the continued presence of both agents in the therapeutic armamentarium remains critically important to this fragile population. The historical use, clinical practice concerns, published comparative studies and methods for optimization of these two bypassing agents are reviewed.

The role of recombinant factor VIIa in on-pump cardiac surgery: Proceedings of the Canadian Consensus Conference

PURPOSE

Recombinant activated factor VII (rFVIIa) is currently not approved by Health Canada or the Food and Drug Administration for treating excessive blood loss in nonhemophiliac patients undergoing on-pump cardiac surgery, but is increasingly being used "off-label" for this indication. A Canadian Consensus Conference was convened to generate recommendations for rFVIIa use in on-pump cardiac surgery.

METHODS

The panel undertook a literature review of the use of rFVIIa in both cardiac and non-cardiac surgery. Appropriateness, timing, and dosage considerations were addressed for three cardiac surgery indications: prophylactic, routine, and rescue uses. Recommendations were based on evidence from the literature and derived by consensus following recognized grading procedures.

RESULTS

The panel recommended against prophylactic or routine use of rFVIIa, as there is no evidence at this time that the benefits of rFVIIa outweigh its potential risks compared with standard hemostatic therapies. On the other hand, the panel made a weak recommendation (grade 2C) for the use of rFVIIa (one to two doses of 35-70 microg.kg(-1)) as rescue therapy for blood loss that is refractory to standard hemostatic therapies, despite the lack of randomized controlled trial data for this indication.

CONCLUSIONS

In cardiac surgery, the risks and benefits of rFVIIa are unclear, but current evidence suggests that its benefits may outweigh its risks for rescue therapy in selected patients. Methodologically rigorous studies are needed to clarify its riskbenefit profile in cardiac surgery patients.

Recombinant factor VIIa in paediatric bleeding disorders ? a 2006 review

Recombinant factor VIIa (rFVIIa) has been used in haemophilia bleeding since its introduction in 1996. It has been found to be safe and effective in the majority of patients with haemophilia who have developed inhibitors. There is increasing use of rFVIIa in many off-label bleeding conditions, but there is a paucity of randomized studies regarding the use of rFVIIa in children. This review will attempt to address and summarize the studies focusing on the role of rFVIIa in both haemophilia and non-haemophilia bleeding conditions in children. rFVIIa has been administered as both bolus and continuous infusions, and at varying doses. Furthermore, adverse events have not reportedly increased in children despite growing experience with its use in the paediatric population.

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.

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

Recombinant activated factor VII (rFVIIa) is a major alternative for management of hemophiliac patients with inhibitors. Additionally, it has been used off-label for the treatment of massive life-threatening hemorrhage associated with various bleeding situations. Herein, we describe a 16-month-old boy with acute megakaryoblastic leukemia and severe intractable gastrointestinal bleeding controlled by rFVIIa. rFVIIa should be considered as a novel treatment alternative in severe bleeding conditions including leukemias that may have hemostatic defects and platelet dysfunction.

Recent advances in the management of the child who has hemophilia

This article discusses recent advances in the management of the child who has hemophilia.

Recombinant factor VIIa: review of efficacy, dosing regimens and safety in patients with congenital and acquired factor VIII or IX inhibitors

Recombinant factor (rF)VIIa has been available to clinicians since 1996 and has an excellent safety record after almost three-quarters of a million doses have been administered. This paper will review the current clinical experience with rFVIIa dosing in acquired and congenital hemophilia with inhibitors and chronicle all spontaneous and clinical trial reports of thrombotic adverse events as of April 2003. Standard dosing of rFVIIa (90 micro g kg(-1)) allows binding of FVIIa to the surface of an activated platelet and can directly activate factor X in the absence of tissue factor. Experience with bolus dosing suggests that higher dosing (>200 micro g kg(-1)) may be more efficacious in treating hemophilia patients. Clinical trials are ongoing to validate this observation. Continuous infusion dosing may be efficacious for major surgery but high infusion rates (50 micro g kg(-1) h(-1)) might be needed. The relationship between dose of rFVIIa, amount of thrombin generated and measurable FVIIa level is still not known and perhaps newer testing which measures thrombin generation might be more advantageous. Relatively few thrombotic events have been associated with rFVIIa. Known factors predisposing to thrombosis were present in 20 of the 25 (80%) hemophilia patients who were reported spontaneously or who developed a thrombosis during a clinical trial. Additionally, thrombotic events have not increased despite a growing experience with higher dosing of rFVIIa.

Use of recombinant factor VIIa in infants with severe coagulopathy

The risk of hemorrhage in infants with severe coagulopathies unresponsive to fresh frozen plasma (FFP) infusions may preclude therapeutic invasive interventional procedures. We describe the successful use of recombinant factor VIIa (rFVIIa) in two such infants, the first with cirrhosis requiring paracentesis and the second with necrotizing enterocolitis requiring laparotomy. This report reviews the current concepts on the mechanism of action of the drug rFVIIa and considers its expanded use in infants unresponsive to FFP replacement.

Recombinant activated factor VII for life-threatening pulmonary hemorrhage after pediatric cardiac surgery

OBJECTIVE

To report intractable life-threatening pulmonary hemorrhage after cardiac surgery in an infant who was treated successfully with recombinant activated factor VII (rFVIIa).

DESIGN

Descriptive case report.

SETTING

An 18-bed pediatric intensive care unit at a tertiary-care children's hospital.

PATIENT

A 10-wk-old child with acute life-threatening pulmonary hemorrhage after cardiac surgery.

INTERVENTIONS

General supportive intensive care.

MEASUREMENTS AND MAIN RESULTS

Care included mechanical ventilatory support, inotropic support, and concurrent treatment with blood products (packed cells, platelet concentrates, and plasma-derived products), as well as aprotinin and desmopressin to improve hemostasis. The addition of rFVIIa resulted in complete resolution of the hemorrhage.

CONCLUSIONS

rFVIIa should be considered as a possible novel therapeutic approach to be used as rescue therapy for patients presenting with massive life-threatening hemorrhage progressing into hemorrhagic shock. Further controlled trials to elucidate the safety of this treatment are warranted.

Recombinant factor VIIa improves coagulopathy caused by liver failure

OBJECTIVE

Coagulopathy is an important cause of morbidity and mortality in patients with liver failure. The benefit of traditional therapies to correct coagulation is often limited and short-lived. Our aim is to identify indications for rFVIIa use and the outcome of treatment in children with liver failure.

METHODS

A retrospective review from July 2000 to December 2001 was performed to identify consecutive patients with acute or chronic liver failure who received rFVIIa. Prothrombin times (PT) before and after therapy were compared by paired t test.

RESULTS

Fifteen patients were treated with rFVIIa for coagulopathy caused by liver failure. All were receiving fresh frozen plasma (mean infusion rate, 39.7 mL/kg/day) when rFVIIa therapy was started. The mean PT before rFVIIa was 32.0 +/- 7.0 seconds. One hour after infusion, the PT normalized to 13.7 +/- 2.4 seconds (P < 0.0001) and remained significantly reduced at 6 hours (19.8 +/- 5.3 seconds; P < 0.0001). A sustained improvement was maintained during the subsequent 3 days. Five of seven patients with bleeding complications improved clinically after rFVIIa treatment. Two of the bleeding patients also benefited from improved fluid balance as fresh frozen plasma support was reduced. No thrombotic events were attributed to rFVIIa therapy.

CONCLUSIONS

In patients with liver failure, rFVIIa therapy quickly normalizes the PT and maintains improved hemostasis, even when coagulopathy has been refractory to fresh frozen plasma. Therapy subjectively reduces clinical bleeding and can improve fluid balance, without complications.

Control of bleeding in patients with haemophilia A with inhibitors: a systematic review

This paper reports a systematic review of the best available evidence of clinical effectiveness in the treatment of acute bleeding in haemophilia A patients with inhibitors. Because of the lack of randomized controlled trials (RCTs) on this topic, broad inclusion criteria with regard to study design were applied in order to assess the best available evidence for each intervention. Because of the clinical and methodological heterogeneity of the evidence, it was not appropriate to pool data across studies; instead, data were synthesized using tabulation and qualitative narrative assessment. No evidence was found to support the use of high-dose factor VIII (FVIII) in bleeding episodes. However in surgery it was found to be highly successful (100%) for low-titre, low-responding inhibitors although not reliable for high-responding inhibitors. Porcine FVIII (pFVIII) was effective in the control of severe bleeding episodes with high-titre or high-responding inhibitors (100%) and in 60-90% of surgical procedures. Activated prothrombin complex concentrates (APCCs) appear to be more effective than prothrombin complex concentrates (PCCs) in the control of mild to severe bleeding episodes. There was no good evidence for the use of PCCs in surgery. APCCs controlled bleeding in approximately 90% of surgical episodes. Recombinant factor VIIa (rFVIIa) controlled 70-100% of mild to severe bleeding episodes with high-responding inhibitors, and achieved better results when used early. It was effective in 60-100% of surgical episodes. Doses varied from study to study, and side-effects from mild to infrequent but serious adverse events were reported. The quality of the evidence is variable. Limited evidence relating to other treatment options is also included in the review.

Successful treatment of acquired factor VIII deficiency in a child using activated factor VII concentrates: case report and review of the literature

Acquired factor VIII deficiency is a rare life-threatening disorder that should be suspected in individuals without a prior bleeding history who present with mucous membrane, muscle, and/or urinary tract bleeding. The authors describe a 5-year-old girl with epistaxis, intramuscular bleeding, and forearm compartment syndrome requiring emergent fasciotomy. Coagulation studies showed a factor VIII level of less than 1%. The prolonged activated partial thromboplastin time corrected immediately when mixed with normal plasma at a 1:1 ratio but became prolonged again following incubation at 37 degrees C. She was treated successfully with serial administrations of activated factor VII concentrates and immunosuppression with corticosteroids. Activated factor VII concentrates should be considered as an option for patients of all ages with acquired factor VIII deficiency.

Recombinant activated factor VII for the rapid correction of coagulopathy in nonhemophilic neurosurgical patients

OBJECTIVE

Coagulopathy is a significant contraindication for neurosurgery. Unfortunately, many coagulopathic patients require urgent neurosurgical intervention. Standard use of blood products, including fresh-frozen plasma or prothrombin complexes, to correct the coagulopathy often leads to significant delays in treatment. Recombinant activated factor VII (rFVIIa) is a medication originally designed to treat bleeding in hemophiliacs but also seems to correct a wide variety of coagulopathies rapidly and safely in nonhemophilic patients.

METHODS

The medical records of nine patients with coagulopathy requiring urgent neurosurgical intervention were reviewed retrospectively. Each patient was given a dose ranging from 40 to 90 microg/kg of rFVIIa before undergoing surgery. Pre-rFVIIa coagulation and post-rFVIIa coagulation parameters were obtained. Once correction of the coagulopathy was verified, each patient underwent the appropriate neurosurgical procedure.

RESULTS

The average age of the patients was 40.9 years; six were women. The causes of the coagulopathy included anticoagulant medication, liver dysfunction, and dilutional coagulopathy after traumatic hemorrhage. Neurosurgical indications included intraparenchymal/intraventricular hemorrhage, hydrocephalus, diffuse cerebral edema, and epidural hematoma. Post-rFVIIa coagulation parameters obtained as early as 20 minutes after infusion of the medication showed normalization of values. There were no procedural or operative complications and no postoperative hemorrhagic complications. No associated thromboembolic or other complications with the use of rFVIIa were observed.

CONCLUSION

The use of rFVIIa for the urgent surgical treatment of coagulopathic patients is quite promising. Further studies, including randomized, prospective trials using rFVIIa to address issues such as optimal dosing, efficacy, surgical indications, cost-effectiveness, morbidity, and mortality are needed.

Influence of factor VIIa and phospholipids on coagulation in "acquired" hemophilia

OBJECTIVE

This study was performed to evaluate the influences of phospholipids and recombinant factor VIIa (rFVIIa) on thrombin generation and clot formation in "acquired" hemophilia B.

METHODS AND RESULTS

A synthetic mixture corresponding to hemophilia A (SHA) and "acquired" hemophilia B blood (AHBB) manufactured in vitro by an anti-FIX antibody were used in this study. With 10 pmol/L tissue factor (TF), 10 nmol/L rFVIIa, and saturating phospholipid, established thrombin generation in SHA was similar to that observed in the presence of factor VIII and rFVIIa at physiological concentrations. At lower phospholipid concentrations, thrombin generation was delayed and reduced. With 5 pmol/L TF, contact pathway-inhibited AHBB clotted later than normal blood and showed reduced clot stability and thrombin generation. These parameters of effectiveness were increased by the addition of phospholipids to AHBB, which restored clot stability and increased thrombin generation. No correction of clot formation or thrombin generation was observed when rFVIIa and phospholipids were added to AHBB in the absence of TF.

CONCLUSIONS

The influence of rFVIIa is dependent on TF, and phospholipids substantially increase the hemostatic (or thrombotic) potential of rFVIIa/TF.

Continuous infusion of coagulation factor products

OBJECTIVE

To review clinical information related to the use of continuous infusion factor products in patients with hemophilia. Specifically, case reports and open-label trials are summarized involving the use of factor VIII and recombinant factor VIIa for a variety of indications including surgical prophylaxis, acute bleeding, primary prevention, and management of inhibitors. In addition, issues surrounding the use of continuous infusion of factor products such as pharmacokinetic rationale, stability/sterility, and cost are reviewed.

DATA SOURCES

Primary and review articles were identified through a MEDLINE search (1990-June 2001) and through secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All articles identified from the data sources were evaluated, and all information deemed relevant was included in this review.

DATA SYNTHESIS

Data concerning the administration of factor products are primarily detailed in open-label trials and case reports. Comparisons between intermittent bolus injections and continuous infusion of factor products are limited and primarily compare continuous infusion regimens with historical controls. The rationale behind the continuous-infusion approach is linked to the pharmacokinetics of factor products administered via this route. Pharmacokinetic data reveal that, with continuous infusion of factor products, a reduction in clearance and a maintenance of factor serum concentrations are noted.

CONCLUSIONS

Administration of factor products (factor VIII and recombinant factor VIIa) via continuous infusion has produced favorable hemostatic effects compared with intermittent bolus injections. The advantages of continuous infusion include maintenance of a constant factor concentration, thereby reducing risk of bleeding from excessively low trough concentrations, and a decrease in factor consumption related to a reduction in factor clearance with constant infusion. Manufacturers recommend using reconstituted factor products either immediately or within 1-3 hours after reconstitution; however, several studies have found the products to be stable and sterile for longer periods.

Mechanism of factor VIIa-dependent coagulation in hemophilia blood

The ability of factor VIIa to initiate thrombin generation and clot formation in blood from healthy donors, blood from patients with hemophilia A, and in anti-factor IX antibody-induced ("acquired") hemophilia B blood was investigated. In normal blood, both factor VIIa-tissue factor (TF) complex and factor VIIa alone initiated thrombin generation. The efficiency of factor VIIa was about 0.0001 that of the factor VIIa-TF complex. In congenital hemophilia A blood and "acquired" hemophilia B blood in vitro, addition of 10 to 50 nM factor VIIa (pharmacologic concentrations) corrected the clotting time at all TF concentrations tested (0-100 pM) but had little effect on thrombin generation. Fibrinopeptide release and insoluble clot formation were only marginally influenced by addition of factor VIIa. TF alone had a more pronounced effect on thrombin generation; an increase in TF from 0 to 100 pM increased the maximum thrombin level in "acquired" hemophilia B blood from 120 to 480 nM. Platelet activation was considerably enhanced by addition of factor VIIa to both hemophilia A blood and "acquired" hemophilia B blood. Thus, pharmacologic concentrations of factor VIIa cannot restore normal thrombin generation in hemophilia A and hemophilia B blood in vitro. The efficacy of factor VIIa (10-50 nM) in hemophilia blood is dependent on TF.