Recombinant-activated coagulation factor VIIa (NovoSeven®): current development

Use of recombinant factor VIIa (rFVIIa) as pre-hospital treatment in a swine model of fluid percussion traumatic brain injury

CONTEXT

Recombinant factor VIIa (rFVIIa) has been used as an adjunctive therapy for acute post-traumatic hemorrhage and reversal of iatrogenic coagulopathy in trauma patients in the hospital setting. However, investigations regarding its potential use in pre-hospital management of traumatic brain injury (TBI) have not been conducted extensively.

AIMS

In the present study, we investigated the physiology, hematology and histology effects of a single pre-hospital bolus injection of rFVIIa compared to current clinical practice of no pre-hospital intervention in a swine model of moderate fluid percussion TBI.

MATERIALS AND METHODS

Animals were randomized to receive either a bolus of rFVIIa (90 μg/kg) or nothing 15 minutes (T15) post-injury. Hospital arrival was simulated at T60, and animals were euthanized at experimental endpoint (T360).

RESULTS

Survival was 100% in both groups; baseline physiology parameters were similar, vital signs were comparable. Animals that received rFVIIa demonstrated less hemorrhage in subarachnoid space (P = 0.0037) and less neuronal degeneration in left hippocampus, pons, and cerebellum (P = 0.00009, P = 0.00008, and P = 0.251, respectively). Immunohistochemical staining of brain sections showed less overall loss of microtubule-associated protein 2 (MAP2) and less Flouro-Jade B positive cells in rFVIIa-treated animals.

CONCLUSIONS

Early pre-hospital administration of rFVIIa in this swine TBI model reduced neuronal necrosis and intracranial hemorrhage (ICH). These results merit further investigation of this approach in pre-hospital trauma care.

Safety and efficacy of recombinant activated factor VII for refractory hemorrhage in pediatric patients on extracorporeal membrane oxygenation: a single center review

Background:

Medically refractory hemorrhage in patients on ECMO (extracorporeal membrane oxygenation) support can have catastrophic complications. Recombinant-Activated Factor VII (rFVIIa; NovoSeven®) may provide lifesaving hemostasis; however, there are reports of catastrophic thrombosis related to its administration.

Objective:

This review attempts to add safety and efficacy data to existing literature regarding the use of rFVIIa for refractory hemorrhage in pediatric patients on ECMO support.

Design/Methods:

A retrospective chart review was performed for all pediatric patients on ECMO who received rFVIIa for refractory hemorrhage from 2004 to 2009. Data was extracted for each refractory bleeding event, including patient blood loss and transfused blood products in the 6 hours before the first dose, between rFVIIa doses and in the 6 hours after the final dose. For purposes of data collection, a hemorrhagic event was defined as new onset hemorrhage or a hemorrhage occurring at least 12 hours after the most recent dose of rFVIIa.

Results:

In total, seven patients aged 1 month to 15 years received rFVIIa for 14 different hemorrhagic events. There was no significant difference in blood loss or blood product transfusion associated with rFVIIa administration. There was one patient-related and one ECMO-related complication temporally associated with rFVIIa administration: decreased ECMO circuit oxygenator efficiency and the development of an intra-gastric clot requiring surgical evacuation.

Conclusion:

These data suggest limited efficacy for rFVIIa use for refractory hemorrhage in pediatric patients on ECMO support. There were two non-catastrophic complications temporally associated with its administration.

Expression of recombinant human coagulation factor VII by the Lizard Leishmania expression system

The variety of recombinant protein expression systems have been developed as a resource of FVII gene expression. In the current study, the authors used a novel protein expression system based on the Iranian Lizard Leishmania, a trypanosomatid protozoan as a host for expression of FVII. Plasmid containing cDNA encoding full-length human FVII was introduced into Lizard Leishmania and positive transfectants were analyzed by SDS-PAGE and Western blot analysis. Furthermore, biological activity of purified protein was detected by PT assay. The recombinant strain harboring a construct was analyzed for expression of FVII at the mRNA and protein level. Purified rFVII was obtained and in order to confirm the purified compound was in fact rFVII. Western blot analysis was carried out. Clotting time in PT assay was reduced about 30 seconds with the purified rFVII. In Conclusion, this study has demonstrated, for the first time, that Leishmania cells can be used as an expression system for producing recombinant FVII.

Prothrombin complex concentrate versus recombinant factor VIIa for reversal of hemodilutional coagulopathy in a porcine trauma model

BACKGROUND

Fluid resuscitation after traumatic injury may necessitate coagulation factor replacement to prevent bleeding complications of dilutional coagulopathy. Recombinant activated factor VII (rFVIIa) is being widely investigated as a hemostatic agent in trauma. Multicomponent therapy with prothrombin complex concentrate (PCC) containing coagulation factors II, VII, IX, and X might offer potential advantages.

METHODS

Anesthetized mildly hypothermic normotensive pigs were hemodiluted by substituting 65% to 70% of total blood volume in phases with hydroxyethyl starch and red cells. Thereafter, animals received 12.5 mL . kg isotonic saline placebo, 35 IU . kg PCC, or 180 microg x kg rFVIIa. Immediately afterward, a standardized spleen injury was inflicted, and prothrombin time (PT) and hemostasis were assessed. Thrombin generation was also determined.

RESULTS

Hemodilution depleted levels of factors II, VII, IX, and X markedly, prolonged PT and decreased thrombin formation. PCC and rFVIIa both fully normalized the hemodilution-induced lengthening of PT. In PCC recipients, peak thrombin generation was greater by a median of 60.7 nM (confidence interval 56.4-64.9 nM) compared with the rFVIIa group (p = 0.008). After spleen trauma, time to hemostasis was shortened to a median of 35 minutes in animals treated with PCC versus 94 minutes with rFVIIa (p = 0.016).

CONCLUSIONS

In a pilot study involving an in vivo large-animal model of spleen trauma, PCC accelerated hemostasis and augmented thrombin generation compared with rFVIIa. Further investigations are warranted on PCC as a hemostatic agent in trauma.

The use of recombinant FVIIa in a patient with Glanzmann thrombasthenia with uncontrolled bleeding after tonsillectomy

Glanzmann's thrombasthenia is an inherited platelet function disorder caused by quantitative or qualitative defects of the platelet membrane glycoprotein IIb/IIIa complex. Activated recombinant factor VII (rFVIIa) has recently been used in the treatment of patients with Glanzmann's thrombasthenia. We report herein a 16-year-old boy with Glanzmann's thrombasthenia who did not respond to conservative treatment for excessive bleeding and hyperfibrinolysis after tonsillectomy and who was successfully treated with rFVIIa. We suggest that rFVIIa at repeated doses of 80-100 microg/kg may be used effectively in patients with Glanzmann's thrombasthenia having excessive bleeding associated with hyperfibrinolysis after tonsillectomy in addition to tranexamic acid treatment.

Can a Subset of Intracerebral Hemorrhage Patients Benefit From Hemostatic Therapy With Recombinant Activated Factor VII?

Background and Purpose— In the Factor Seven for Acute Hemorrhagic Stroke (FAST) trial, 80 μg/kg of recombinant activated factor VII (rFVIIa) significantly reduced intracerebral hemorrhage (ICH) expansion when given within 4 hours of onset. However, in contrast to an earlier Phase 2b study, rFVIIa did not improve survival or functional outcome. In this exploratory analysis, we hypothesized that earlier treatment and exclusion of patients with a poor prognosis at baseline might enhance the benefit of rFVIIa treatment.

Methods— Using the FAST data set, the impact of rFVIIa (80 μg/kg) on poor outcome at 3 months (modified Rankin Score of 5 or 6) was systematically evaluated within subgroups using clinically meaningful cut points in onset-to-treatment time, age, and baseline ICH and intraventricular hemorrhage volume. The effect of treatment on outcome was analyzed using logistic regression, and ICH volume was analyzed with linear mixed models.

Results— A subgroup (n=160, 19% of the FAST population) was identified comprising patients ≤70 years with baseline ICH volume <60 mL, intraventricular hemorrhage volume <5 mL, and time from onset-to-treatment ≤2.5 hours. The adjusted ORs for poor outcome with rFVIIa treatment was 0.28 (95% CI, 0.08 to 1.06), whereas the reduction in ICH growth was almost doubled (7.3±3.2 versus 3.8±1.5 mL, P =0.02). The improved effect was confirmed in an analysis of similar Phase 2 patients.

Conclusions— A prospective trial would be needed to determine whether younger patients with ICH without extensive bleeding at baseline can benefit from 80 μg/kg of rFVIIa given within 2.5 hours of symptom onset.

Differential clot stabilising effects of rFVIIa and rFXIII-A2 in whole blood from thrombocytopenic patients and healthy volunteers

The haemostatic effect of recombinant activated factor VII (rFVIIa;NovoSeven) in thrombocytopenic patients has been a matter of controversy. Haemostasis by rFVIIa occurs via FVIIa-mediated thrombin generation in a platelet-dependent manner and may therefore be suboptimal in patients without functional platelets. Under such conditions, a clot-stabilizing agent, such as factor XIII (FXIII), may supplement the effect ofrFVIIa and improve haemostasis. Recombinant factor XIII (rFXIII-A2) is produced as an A2 homodimer of the FXIII A subunit and is equivalent to cellular FXIII normally found in platelets. The combined effects of rFVIIa andrFXIII-A2 were evaluated in clot lysis assays using factor XIII-deficient plasma and by whole blood thrombelastography (TEG) analysis from normal donors and thrombocytopenic stem cell transplantation patients. Clotting time was shortened by rFVIIa (0.6-10 microg/ml). rFVIIa only modestly improved anti-fibrinolysis,whereas rFXIII-A2 (0-20 microg/ml) enhanced anti-fibrinolysis without effect on clotting time. TEG analysis showed rFVIIa shortened the clotting time, and enhanced clot development, maximal mechanical strength and resistance to fibrinolysis, whereas, rFXIII-A2 enhanced clot development,maximal mechanical strength and markedly enhanced resistance to fibrinolysis. These data illustrate that rFVIIa and rFXIII-A2 contribute to clot formation and stability by different mechanisms suggesting enhanced haemostatic efficacy by combining these agents.

Use of rFVIIa in the Trauma Setting–Practice Patterns in United States Trauma Centers

Much excitement has been generated regarding the off label use of recombinant factor VIIa (rFVIIa) in the severely injured trauma patient. The purpose of our study is 3-fold: 1) describe the type of centers that use rFVIIa, 2) determine which centers use the drug more frequently, and finally 3) investigate how this drug is being administered at trauma centers. A survey was mailed or e-mailed to 435 trauma centers (Level I and II) throughout the nation. One hundred fifty-six surveys were returned. American College of Surgeons (ACS) verification and trauma Level I designation were independent predictors of rFVIIa use (odds ratio [OR] 3.74 and 5.40, P < 0.05). High users of rFVIIa were defined as those centers that had above median usage of the drug. Level I centers accounted for 67 per cent of the high users. Only the number of fellowship-trained trauma surgeons and trauma volume predicted high usage of rFVIIa (OR 1.38 and 14.09, P < 0.05). Trauma volume predicted whether or not Factor VII users implemented a protocol based approach to administration of the drug (OR 6.57, P < 0.05). Most protocols incorporated packed red blood cells (74%) before giving rFVIIa. The dose of 90 mcg/kg was exceeded in 34 per cent of centers, and 3 per cent used the 200 mcg/kg dose. High volume Level I trauma centers use rFVIIa more frequently and are more likely to use a systematic approach to its administration. However, there is no standardized approach to rFVIIa administration in United States trauma centers.

Acceptability of blood and blood substitutes

Alternatives to donor blood have been developed in part to meet increasing demand. However, new biotechnologies are often associated with increased perceptions of risk and low acceptance. This paper reviews developments of alternatives and presents data, from a field-based experiment in the UK and Holland, on the risks and acceptance of donor blood and alternatives (chemical, genetically modified and bovine). UK groups perceived all substitutes as riskier than the Dutch. There is a negative association between perceived risk and acceptability. Solutions to increasing acceptance are discussed in terms of implicit attitudes, product naming and emotional responses.

Scientific aspects of supplying blood to distant military theaters

PURPOSE OF REVIEW

Reduction in combat zone morbidity and mortality requires rapid delivery of safe blood products as an integral element of advanced trauma surgical care. This review of the current literature presents scientific aspects of supplying blood for rapid delivery to enhance survival and patient outcome in the combat zone.

RECENT FINDINGS

Most deaths due to hemorrhage can be averted by transfusion during the first hour from injury; therefore, maintaining a dependable inventory of blood products in combat support hospitals is essential. Current casualty care in distant geographic locations involves rapid air evacuation to combat support hospitals or fleet hospitals, where massive transfusions may be required. Resuscitation by forward surgical teams utilizing red blood cells before air evacuation or in-flight has also been reported. To improve survival, these massive transfusions should be composed of not only red blood cells but also other blood components and plasma factors.

SUMMARY

Rapid on-site combat casualty transfusion support requires specialized blood transport containers and transfusion practices not observed in noncombat settings, such as the mobile walking blood bank and a frozen blood program. Additionally, technology for improved transport containers, cell-free hemoglobin-based oxygen carriers, freeze-dried blood, and recombinant activated coagulation factor has attracted focused interest.