Pharmacokinetics of recombinant activated factor VII (rFVIIa)

Predicting Pharmacokinetics of Drugs Using Artificial Intelligence Tools: A Systematic Review

BACKGROUND AND OBJECTIVE

Pharmacokinetic studies encompass the examination of the absorption, distribution, metabolism, and excretion of bioactive compounds. The pharmacokinetics of drugs exert a substantial influence on their efficacy and safety. Consequently, the investigation of pharmacokinetics holds great importance. However, laboratory-based assessment necessitates the use of numerous animals, various materials, and significant time. To mitigate these challenges, alternative methods such as artificial intelligence have emerged as a promising approach. This systematic review aims to review existing studies, focusing on the application of artificial intelligence tools in predicting the pharmacokinetics of drugs.

METHODS

A pre-prepared search strategy based on related keywords was used to search different databases (PubMed, Scopus, Web of Science). The process involved combining articles, eliminating duplicates, and screening articles based on their titles, abstracts, and full text. Articles were selected based on inclusion and exclusion criteria. Then, the quality of the included articles was assessed using an appraisal tool.

RESULTS

Ultimately, 23 relevant articles were included in this study. The clearance parameter received the highest level of investigation, followed by the  area under the concentration-time curve (AUC) parameter, in pharmacokinetic studies. Among the various models employed in the articles, Random Forest and eXtreme Gradient Boosting (XGBoost) emerged as the most commonly utilized ones. Generalized Linear Models and Elastic Nets (GLMnet) and Random Forest models showed the most performance in predicting clearance.

CONCLUSION

Overall, artificial intelligence tools offer a robust, rapid, and precise means of predicting various pharmacokinetic parameters based on a dataset containing information of patients or drugs.

An engineered human albumin enhances half-life and transmucosal delivery when fused to protein-based biologics

Needle-free uptake across mucosal barriers is a preferred route for delivery of biologics, but the efficiency of unassisted transmucosal transport is poor. To make administration and therapy efficient and convenient, strategies for the delivery of biologics must enhance both transcellular delivery and plasma half-life. We found that human albumin was transcytosed efficiently across polarized human epithelial cells by a mechanism that depends on the neonatal Fc receptor (FcRn). FcRn also transported immunoglobulin G, but twofold less than albumin. We therefore designed a human albumin variant, E505Q/T527M/K573P (QMP), with improved FcRn binding, resulting in enhanced transcellular transport upon intranasal delivery and extended plasma half-life of albumin in transgenic mice expressing human FcRn. When QMP was fused to recombinant activated coagulation factor VII, the half-life of the fusion molecule increased 3.6-fold compared with the wild-type human albumin fusion, without compromising the therapeutic properties of activated factor VII. Our findings highlight QMP as a suitable carrier of protein-based biologics that may enhance plasma half-life and delivery across mucosal barriers.

Phase 1, single-dose escalating study of marzeptacog alfa (activated), a recombinant factor VIIa variant, in patients with severe hemophilia

Essentials Marzeptacog alfa (activated) [MarzAA] is a novel variant of activated human factor VII. A phase 1 dose escalation trial of MarzAA was conducted in subjects with severe hemophilia. MarzAA was safe and tolerated at intravenous doses up to 30 μg kg-1 Data observed support further trials for hemophilia patients with inhibitors to factors VIII/IX.

SUMMARY

Background Marzeptacog alfa (activated) (MarzAA), a new recombinant activated human factor VII (rFVIIa) variant with four amino acid substitutions, was developed to provide increased procoagulant activity and a longer duration of action in people with hemophilia. Objectives To investigate the safety, tolerability, immunogenicity, pharmacokinetics (PK) and pharmacodynamics (PD) of single ascending intravenous bolus doses of MarzAA in non-bleeding patients with congenital hemophilia A or B with or without inhibitors. Methods This international, phase 1, open-label study (NCT01439971) enrolled males aged 18-64 years with severe hemophilia A or B, with or without FVIII or FIX inhibitors. Subjects were assigned to single-dose MarzAA cohorts (0.5, 4.5, 9, 18 or 30 μg kg-1 ). Blood sampling was performed predose and postdose, and subjects were monitored for 60 days postdose. Safety endpoints included adverse events, vital sign changes, electrocardiograms, laboratory abnormalities, and immunogenicity; secondary endpoints included evaluation of PK and PD. Results Overall, in 25 patients, MarzAA was well tolerated at all dose levels tested, and was not associated with dose-limiting toxicity. No treatment-emergent severe or serious adverse events occurred. MarzAA showed linear dose-response PK across the 4.5-30 μg kg-1 dose range, with a terminal half-life of ⁓ 3.5 h. Dose-dependent shortening of the activated partial thromboplastin time and prothrombin time, and evidence of an increase in peak thrombin as determined with a thrombin generation assay, were observed at all doses. Conclusions MarzAA was tolerated at doses up to 30 μg kg-1 . The safety profile and pharmacological effects observed support further clinical trials for the treatment of hemophilic patients with inhibitors.

Spanish Consensus Guidelines on prophylaxis with bypassing agents in patients with haemophilia and inhibitors

Prophylaxis with the blood clotting factor, factor VIII (FVIII) is ineffective for individuals with haemophilia A and high-titre inhibitors to FVIII. Prophylaxis with the FVIII bypassing agents activated prothrombin complex concentrates (aPCC; FEIBA® Baxalta) or recombinant activated factor VII (rFVIIa; Novo-Seven®, Novo Nordisk) may be an effective alternative. It was our aim to develop evidence -and expert opinion- based guidelines for prophylactic therapy for patients with high-titre inhibitors to FVIII. A panel of nine Spanish haematologists undertook a systematic review of the literature to develop consensusbased guidance. Particular consideration was given to prophylaxis in patients prior to undergoing immune tolerance induction (ITI) (a process of continued exposure to FVIII that can restore sensitivity for some patients), during the ITI period and for those not undergoing ITI or for whom ITI had failed. These guidelines offer guidance for clinicians in deciding which patients might benefit from prophylaxis with FVIII bypassing agents, the most appropriate agents in various clinical settings related to ITI, doses and dosing regimens and how best to monitor the efficacy of prophylaxis. The paper includes recommendations on when to interrupt or stop prophylaxis and special safety concerns during prophylaxis. These consensus guidelines offer the most comprehensive evaluation of the clinical evidence base to date and should be of considerable benefit to clinicians facing the challenge of managing patients with severe haemophilia A with high-titre FVIII 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.

Sustained correction of FVII deficiency in dogs using AAV-mediated expression of zymogen FVII

Factor VII (FVII) deficiency is a rare autosomal recessive bleeding disorder treated by infusion of fresh-frozen plasma, plasma-derived FVII concentrates and low-dose recombinant activated FVII. Clinical data suggest that a mild elevation of plasma FVII levels (>10% normal) results in improved hemostasis. Research dogs with a G96E missense FVII mutation (FVII-G96E) have <1% FVII activity. By western blot, we show that they have undetectable plasmatic antigen, thus representing the most prevalent type of human FVII deficiency (low antigen/activity). In these dogs, we determine the feasibility of a gene therapy approach using liver-directed, adeno-associated viral (AAV) serotype 8 vector delivery of a canine FVII (cFVII) zymogen transgene. FVII-G96E dogs received escalating AAV doses (2E11 to 4.95E13 vector genomes [vg] per kg). Clinically therapeutic expression (15% normal) was attained with as low as 6E11 vg/kg of AAV and has been stable for >1 year (ongoing) without antibody formation to the cFVII transgene. Sustained and supraphysiological expression of 770% normal was observed using 4.95E13 vg/kg of AAV (2.6 years, ongoing). No evidence of pathological activation of coagulation or detrimental animal physiology was observed as platelet counts, d-dimer, fibrinogen levels, and serum chemistries remained normal in all dogs (cumulative 6.4 years). We observed a transient and noninhibitory immunoglobulin G class 2 response against cFVII only in the dog receiving the highest AAV dose. In conclusion, in the only large-animal model representing the majority of FVII mutation types, our data are first to demonstrate the feasibility, safety, and long-term duration of AAV-mediated correction of FVII deficiency.

Recombinant Factor VIIa: clinical applications for an intravenous hemostatic agent with broad-spectrum potential

Recombinant Factor VIIa (NovoSeven, Novo Nordisk) is a unique hemostatic agent with potential for broad-spectrum applications in bleeding patients with congenital and acquired bleeding abnormalities. At present, recombinant Factor VIIa is only approved for the treatment of hemophilia A and B patients who have acquired antibodies to Factors VIII and IX. However, the literature is rapidly expanding indicating that rFVIIa could benefit patients with bleeding due to a variety of etiologies. Unfortunately, the vast majority of these reports are case studies or small-series summaries, and are neither prospective nor controlled. Controlled trials are currently underway in several potential areas of application. While the possibility of thrombotic complications has been a clinical concern, safety data on patients treated to date have not revealed a significant problem. Expansion of the clinical applications for this interesting and important hemostatic agent are hampered by its expense, the limited scope of the US Food and Drug Administration approval for its use, and the absence of an appropriate laboratory monitoring assay.

Innovative coagulation factors: albumin fusion technology and recombinant single-chain factor VIII

Albumin fusion technology has been used to enhance the pharmacokinetic properties of recombinant coagulation factors. The goal of linking albumin to coagulation factors is to extend the half-life of the coagulation factor, thereby allowing for less frequent dosing for patients with bleeding disorders, such as hemophilia. The novel recombinant fusion proteins linking coagulation factors VIIa and IX with albumin (rVIIa-FP and rIX-FP, respectively) have a longer half-life and similar hemostatic efficacy compared with available recombinant coagulation factor products. Clinical evaluation of these fusion proteins is underway, and preliminary results with rIX-FP in patients with hemophilia B are encouraging. Other advances in coagulation factor therapy include a unique recombinant single-chain factor VIII (FVIII) protein, which has improved intrinsic stability and a higher affinity for von Willebrand factor (VWF), relative to other recombinant FVIIIs, and a recombinant VWF-albumin fusion protein (rVWF-FP), which has a significant longer half-life compared to available VWF products. Evaluation of these novel recombinant proteins continues and will help determine their potential to enhance the management of patients with bleeding disorders.

Extending the pharmacokinetic half-life of coagulation factors by fusion to recombinant albumin

The prophylactic treatment of haemophilia B and the management of haemophilia A or B with inhibitors demand frequent administrations of coagulation factors due to the suboptimal half-lives of the products commercially available and currently in use, e.g. recombinant factor IX (rFIX) and recombinant factor VIIa (rFVIIa), respectively. The extension of the half-lives of rFIX and rFVIIa could allow for longer intervals between infusions and could thereby improve adherence and clinical outcomes and may improve quality of life. Albumin fusion is one of a number of different techniques currently being examined to prolong the half-life of rFIX and rFVIIa. Results from a phase I clinical trial demonstrated that the recombinant fusion protein linking FIX to albumin (rIX-FP) has a five-times longer half-life than rFIX, and preclinical studies with the recombinant fusion protein linking FVIIa to albumin (rVIIa-FP) suggest that rVIIa-FP possesses a significantly extended half-life versus rFVIIa. In this review, we describe albumin fusion technology and examine the recent progress in the development of rIX-FP and rVIIa-FP.

Phase I, randomized, double-blind, placebo-controlled, single-dose escalation study of the recombinant factor VIIa variant BAY 86-6150 in hemophilia

BACKGROUND

BAY 86-6150 is a new human recombinant factor VIIa variant developed for high procoagulant activity and longer action in people with hemophilia with inhibitors.

OBJECTIVES

To investigate the safety, tolerability, pharmacodynamics, pharmacokinetics and immunogenicity of BAY 86-6150 in non-bleeding hemophilia subjects.

METHODS

The study included non-bleeding men (18-65 years of age) with moderate or severe hemophilia A or B with or without inhibitors. Sixteen subjects were randomized 3 : 1 to four cohorts of escalating doses of BAY 86-6150 (6.5, 20, 50 or 90 μg kg(-1) [n = 3 per cohort]) or placebo (n = 1 per cohort); an independent data-monitoring committee reviewed previous cohort data before the next dose escalation. Blood sampling was performed predose and postdose; subjects were monitored for 50 days postdose.

RESULTS

At the tested doses, BAY 86-6150 was not associated with clinically significant adverse events or dose-limiting toxicities. BAY 86-6150 pharmacokinetics exhibited a linear dose response, with a half-life of 5-7 h. Subjects demonstrated consistent, dose-dependent thrombin generation ex vivo in platelet-poor plasma (PPP) (mean peak effect, 26-237 nm thrombin from 6.5 to 90 μg kg(-1)). Peak thrombin levels over time paralleled BAY 86-6150, with thrombin kinetics appearing to be slightly shorter; thus, circulating BAY 86-6150 retained activity. There were corresponding decreases in activated partial thromboplastin and prothrombin times. No subject developed de novo anti-BAY 86-6150 neutralizing antibodies during the 50-day follow-up.

CONCLUSIONS

In this first-in-human, multicenter, randomized, double-blind, placebo-controlled, single-dose escalation study, BAY 86-6150 was tolerated at the highest dose (90 μg kg(-1)), with no safety concerns. Safety and efficacy will be further evaluated in phase II/III studies.

Human recombinant activated factor VII for upper gastrointestinal bleeding in patients with liver diseases

BACKGROUND

Mortality from upper gastrointestinal bleeding in patients with liver disease is high. Recombinant human activated factor VII (rHuFVIIa) has been suggested for patients with liver disease and upper gastrointestinal bleeding.

OBJECTIVES

To assess the beneficial and harmful effects of rHuFVIIa in patients with liver disease and upper gastrointestinal bleeding.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register (December 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 4, 2011), MEDLINE (1948 to December 2011), EMBASE (1980 to December 2011), Science Citation Index Expanded (1900 to December 2011), and LILACS (December 2011). We sought additional randomised trials from the reference lists of the trials and reviews identified through the electronic searches.

SELECTION CRITERIA

Randomised clinical trials.

DATA COLLECTION AND ANALYSIS

Outcome data from randomised clinical trials were extracted and were presented using random-effects model meta-analyses. Data on the risk of bias in the included trials were also extracted.

MAIN RESULTS

We included two trials with 493 randomised participants with various Child-Pugh scores. The trials had a low risk of bias. The rHuFVIIa administration did not reduce the risk of mortality within five days (21/288 (7.3%) versus 15/205 (7.3%); risk ratio (RR) 0.88, 95% confidence interval (CI) 0.48 to 1.64, I(2) = 49%) and within 42 days (5/286 (1.7%) versus 36/205 (17.6%); RR 1.01, 95% CI 0.55 to 1.87, I(2) = 55%) when compared with placebo. Trial sequential analysis demonstrated that there is sufficient evidence to exclude that rHuFVIIa decreases mortality by 80%, but there is insufficient evidence to exclude smaller effects. The rHuFVIIa did not increase the risk of adverse events by number of patients (218/297 (74%) and 164/210 (78%); RR 0.94, 95% CI 0.84 to 1.04, I(2) = 1%), serious adverse events by adverse events reported (164/590 (28%) versus 123/443 (28%); RR 0.91, 95% CI 0.75 to 1.11, I(2) = 0%), and thromboembolic adverse events (16/297 (5.4%) versus 14/210 (6.7%); RR 0.80, 95% CI 0.40 to 1.60, I(2) = 0%) when compared with placebo.

AUTHORS' CONCLUSIONS

We found no evidence to support or reject the administration of rHuFVIIa for patients with liver disease and upper gastrointestinal bleeding. Further adequately powered randomised clinical trials are needed in order to evaluate the proper role of rHuFVIIa for treating upper gastrointestinal bleeding in patients with liver disease. Although the results are based on trials with low risk of bias, the heterogeneity and the small sample size result in rather large confidence intervals that cannot exclude the possibility that the intervention has some beneficial or harmful effect. Further trials with alow risk of bias are required to make more confident conclusions about the effects of the intervention.

Cost effectiveness of prophylactic treatment with activated prothrombin complex concentrate in a patient with inhibitor-positive hemophilia A

Patients with hemophilia and high titers of inhibitors are hard to treat during bleeding events and consequently are more likely to incur high treatment costs and to experience deterioration in quality of life. We report here the case of a boy with hemophilia A and high titers of inhibitors who responded well to prophylactic activated prothrombin complex concentrate (APCC) treatment. Previously, he had to be hospitalized frequently because of painful bleeding of target joints of the knee and ankle. At the age of 4 years and 3 months, APCC prophylaxis at a dose of 60 U/kg, three times a week, was initiated together with on-demand therapy with recombinant factor VIIa. This reduced the frequency and severity of bleeding and ended the need for hospitalization. This, together with a decreased requirement for bypass agents, APCC treatment significantly reduced the cost of treatment for this patient.

Pharmacokinetics, pharmacodynamics and safety of recombinant canine FVIIa in a study dosing one haemophilia A and one haemostatically normal dog

Recombinant human FVIIa (rhFVIIa) corrects the coagulopathy in hemophilia A and B as well as FVII deficiency. This is also the case in dogs until canine anti-human FVIIa antibodies develop (~2 weeks). Recombinant canine factor VIIa (rcFVIIa), successfully over-expressed by gene transfer in haemophilia dogs, has provided long-term haemostasis (>2 years). However, pharmacokinetics (PK), pharmacodynamics (PD) and safety of rcFVIIa after pharmacological administration have not been reported. We therefore wanted to explore the safety, PK and PD of rcFVIIa in dogs. A pilot study was set up to evaluate the safety as well as PK and PD of rcFVIIa after a single intravenous dose of 270 μg kg(-1) to one HA and one haemostatically normal dog and to directly compare rcFVIIa with rhFVIIa in these two dogs. Single doses of rcFVIIa and rhFVIIa were well tolerated. No adverse events were observed. Pharmacokinetic characteristics including half-life (FVIIa activity: 1.2-1.8 h; FVIIa antigen 2.8-3.7 h) and clearance were comparable for rcFVIIa and rhFVIIa. Kaolin-activated thromboelastography approached normal in the HA dog with the improvement being most pronounced after rcFVIIa. This study provided the first evidence that administering rcFVIIa intravenously is feasible, safe, well tolerated and efficacious in correcting the haemophilic coagulopathy in canine HA and that rcFVIIa exhibits pharmacokinetic characteristics comparable to rhFVIIa in haemophilic and haemostatically competent dogs. This strengthens the hypothesis that rcFVIIa can be administered to dogs to mimic the administration of rhFVIIa to humans.

Redistribution and hemostatic action of recombinant activated factor VII associated with platelets

Clinical evidence accumulated from hemophilic patients during prophylaxis with recombinant activated factor VII (rFVIIa) suggests that the duration of the hemostatic action of rFVIIa exceeds its predicted plasma half-life. Mechanisms involved in this outcome have not been elucidated. We have investigated in vitro the redistribution of rFVIIa in platelets from healthy donors, patients with FVII deficiency, and one patient with Bernard-Soulier syndrome. Platelet-rich plasma was exposed to rFVIIa (3 to 60 μg/mL). Flow cytometry, immunocytochemistry, and coagulation tests were applied to detect and quantify rFVIIa. The hemostatic effect of rFVIIa associated to platelets was evaluated using perfusion models. Our studies revealed a dose-dependent association of rFVIIa to the platelet cytoplasm with redistribution into the open canalicular system, and α granules. Mechanisms implicated in the internalization are multiple, involve GPIb and GPIV, and require phospholipids and cytoskeletal assembly. After platelet activation with thrombin, platelets exposed rFVIIa on their membrane. Perfusion studies revealed that the presence of 30% of platelets containing FVIIa improved platelet aggregate formation and enhanced fibrin generation (P < 0.01 versus control). Our results indicate that, at therapeutic concentrations, rFVIIa can be internalized into platelets, where it is protected from physiological clearance mechanisms and can still promote hemostatic activity. Redistribution of rFVIIa into platelets may explain the prolonged prophylactic effectiveness of rFVIIa in hemophilia.

Some technical considerations of open thoracoabdominal aortic aneurysm repair in a transition country

A variety of operative approaches and protective adjuncts have been used in thoracoabdominal aneurysm (TAA) repair to minimize the major complications of perioperative death and spinal cord ischemia. There is no consensus with respect to the optimal approach. We present 118 surgically treated patients over a 10-year period. The present study reviews our experience as a transition country (Serbia) in the treatment and problems we have encountered during open operative treatment of TAAs. Between 1999 and 2009, the authors reviewed 118 consecutive patients who underwent thoracoabdominal aortic resection using a variety of spinal cord protection. Clinical data collected prospectively were analyzed retrospectively. The purpose of the current study was to review the results of a large series of TAA repairs and to present some technical considerations and complications of open TAA repair. There were seven operative deaths (5.9%): two in the setting of ruptured TAAs, three myocardial infarctions and two due to hemorrhage. All 30 (25.4%) postoperative deaths occurred during the initial hospitalization. Postoperative complications included paraplegia in 11 patients (9.3%); renal failure in eight patients (6.8%), with four patients (3.4%) requiring hemodialysis; pulmonary complications in 75 patients (63.5%); bleeding requiring reoperation in two patients (1.7%) and coagulopathic hemorrhage in five patients (4.2%); cardiac complications in six patients (5.1%); stroke in five patients (4.2%); wound dehiscence in six patients (5.1%); and subdural hemorrhage in one patient (0.87%). Open TAA repair intrinsically has substantial complications, of which spinal cord ischemia and renal failure are the most devastating, despite major progress in our understanding of the pathophysiology and operative strategy. Our current review of data clearly proves that the surgical repair of TAAs remains a challenge even in the 21st century, especially in a country in transition.

Recombinant activated factor VII as treatment for uncontrolled mucosal haemorrhage

We report the use of a haemostatic drug (recombinant activated factor VII (rFVIIa)) in a patient who presented a slow but constant bleed in oesophageal mucosa (which required frequent red blood cell transfusion) due to ingestion of caustic products. The administration of rFVIIa ceased bleeding and allowed mucosal cicatrisation and patient haemodynamic stabilisation and clinical recovery.

Prolonged half-life of glycoPEGylated rFVIIa variants compared to native rFVIIa

INTRODUCTION

Bleeding episodes in haemophilia patients with inhibitors are primarily treated with by-passing agents such as recombinant activated FVII (rFVIIa). Prophylactic treatment with rFVIIa has been shown to significantly reduce the number of bleeding episodes as compared to conventional on-demand haemostatic therapy, and a reduced dosing frequency could present an improved treatment option in inhibitor patients.

MATERIALS AND METHODS

A series of glycoPEGylated rFVIIa derivatives (5-40K PEG) has been produced and their effect and pharmocokinetics have been investigated in several animal species.

RESULTS

The glycoPEGylated rFVIIa derivatives exhibit significant prolongation of half-life in mice, dogs and pigs as measured by rFVIIa clot activity. The clearance of rFVIIa, rFVIIa-5K PEG, rFVIIa-10K PEG, rFVIIa-20K PEG and rFVIIa-40K PEG in minipigs were estimated to 59, 27, 22, 8.7 and 3.1 ml/h/kg, respectively. Across species a reduction in clearance as a function of the size of the attached PEG was observed. By allometric scaling, the compiled pharmacokinetics predicts a human half-life for rFVIIa-10K PEG and rFVIIa-40K PEG of approximately 7 and 12h, respectively. The rFVIIa-10K PEG and rFVIIa-40K PEG are efficacious in stopping a bleed in the haemophilia A mouse tail-bleeding model after intravenous administration.

CONCLUSIONS

GlycoPEGylation of rFVIIa significantly increases the rFVIIa exposure in three animal models, glycoPEGylated rFVIIa compounds are effective in vivo and thus, represents a potential prophylactic treatment option for patients with inhibitors.

Recombinant factor VIIa in trauma patients without coagulation disorders

Recombinant activated factor VIIa (rFVIIa) has many clinical applications for patients with congenital bleeding disorders and in a variety of clinical settings. Additional studies in the future are ongoing and should provide the clinical anesthesiologist an additional option during certain bleeding states. Specific recommendations as to timing of administration and frequent monitoring of ionized calcium status are suggested at this time. Optimization of fibrinogen levels, platelet levels, pH, and body temperature will enhance efficacy of rFVIIa.

Intravascular inhibition of factor VIIa and the analogue NN1731 by antithrombin

NN1731 is a recombinant activated factor VII (rFVIIa) analogue with increased intrinsic activity. This also applies to its reactivity towards antithrombin (AT), the role of which was investigated in a pharmacokinetic (PK) study. NN1731 or rFVIIa was administered to normal and haemophilia A dogs and elimination was measured by FVIIa clot activity, FVIIa- and FVIIa-AT antigen. In vitro AT complex formation was studied in canine plasma spiked with NN1731 or rFVIIa. Based on FVIIa antigen concentrations, PK profiles in normal and haemophilia A dogs were similar for NN1731 and rFVIIa with antigen half lives, t(½) ≈1·8 h. In contrast, PK profiles based on activity measurements were distinctly different. NN1731 induced a strong, short lasting (t(½) ≈0·5 h) pro-coagulant response, whereas rFVIIa induced a lower, longer lasting (t(½) ≈1·1 h) response. Western Blot and FVIIa-AT antigen analysis demonstrated in vivo AT complex formation that accounted for these divergences. AT complex formation with FVIIa or NN1731 in vitro in canine plasma was considerably slower than the in vivo reaction. The results suggest that in vivo inhibition by AT contributes significantly to define drug duration in haemophilia treatment with rFVIIa and in particular with the NN1731 analogue.

Optimal use of recombinant factor VIIa in the control of bleeding episodes in hemophilic patients

One of the last remaining clinical hurdles in the treatment of people with hemophilia is the development of inhibitors. Alloantibodies or autoantibodies directed at coagulation factors render the infusion of coagulation factor concentrates ineffective, and alternative means must be used to achieve hemostasis. Recombinant factor VIIa (rFVIIa) was developed to control bleeding episodes in hemophilic patients with inhibitors. Clinical efficacy in achieving hemostasis in inhibitor patients was demonstrated by a compassionate-use protocol, as well as in randomized controlled trials. To date, over 1.5 million doses of rFVIIa have been given to inhibitor patients, with an excellent efficacy and safety record. Because of its short half-life, alternative means of dosing and infusing rFVIIa have been explored and are reviewed here.

Use of Recombinant Factor VIIa in Gastrointestinal Bleeding in Children with Malignancies: A Case Series

Recombinant factor VIIa (rFVIIa) may be useful in management of severe bleeding in paediatric oncology patients. We described our experience and outcomes in a form of a case series. In all cases, indication was massive gastrointestinal bleeding with haemodynamic instability, persistent thrombocytopenia and coagulopathy despite correction. The range of doses used was 88–102 mcg/kg/dose. Each patient received at least 3 doses. The use of rFVIIa resulted in a reduction in blood product support requirement. rFVIIa was effective in 2 out of 3 patients in stopping the bleeding. There were no drug-related complications. rFVIIa has a critical role to play in the early management of severe bleeding in critically ill paediatric oncology patients.

Bio-distribution of pharmacologically administered recombinant factor VIIa (rFVIIa)

BACKGROUND

Recent clinical studies suggest that the prophylactic use of recombinant factor VIIa (rFVIIa) markedly reduces the number of bleeding episodes in hemophilic patients with inhibitors. Given the short biological half-life of rFVIIa, it is unclear how rFVIIa could be effective in prophylactic treatment.

OBJECTIVES

To examine the extravascular distribution of pharmacologically administered rFVIIa to obtain clues on how rFVIIa could work in prophylaxis.

METHODS

Recombinant mouse FVIIa tagged with AF488 fluorophore (AF488-FVIIa) was administered into mice via the tail vein. At different time intervals following the administration, mice were exsanguinated and various tissues were collected. The tissue sections were processed for immunohistochemistry to evaluate distribution of rFVIIa.

RESULTS

rFVIIa, immediately following the administration, associated with the endothelium lining of large blood vessels. Within 1 h, rFVIIa bound to endothelial cells was transferred to the perivascular tissue surrounding the blood vessels and thereafter diffused throughout the tissue. In the liver, rFVIIa was localized to sinusoidal capillaries and accumulated in hepatocytes. In bone, rFVIIa was accumulated in the zone of calcified cartilage and some of it was retained there for a week. The common finding of the present study is that rFVIIa in extravascular spaces was mostly localized to regions that contain TF expressing cells.

CONCLUSIONS

The present study demonstrates that pharmacologically administered rFVIIa readily associates with the vascular endothelium and subsequently enters into extravascular spaces where it is likely to bind to TF and is retained for extended time periods. This may explain the prolonged pharmacological effect of rFVIIa.

Effect of glycoPEGylation on factor VIIa binding and internalization

SUMMARY

Recombinant coagulation factor VIIa (rFVIIa), which is widely used for treatment of bleeding episodes in haemophilia patients with inhibitors, is cleared from the circulation relatively fast with a plasma half-life of 2-4 h. PEGylation is an established and clinically proven strategy for prolonging the circulatory life-time of bio-therapeutic proteins. The aim of this study was to investigate the effect of glycoPEGylation of rFVIIa on rFVIIa binding to its cellular receptors and its subsequent internalization. rFVIIa and glycoPEGylated rFVIIa were labeled with (125)I and the radio-iodinated proteins were used to monitor rFVIIa binding and uptake in endothelial cells and fibroblasts. FVIIa-TF activity at the cell surface was analyzed by a factor X activation assay. Modification of rFVIIa with PEG impaired rFVIIa binding to both endothelial cell protein C receptor and tissue factor (TF) on cell surfaces. The internalization of PEGylated rFVIIa in endothelial cells and fibroblasts was markedly lower compared to the internalization of rFVIIa in these cells. PEGylated rFVIIa was able to activate factor X on TF expressing cell surfaces at a rate similar to that of unmodified rFVIIa when the cells were not subjected to multiple washings to remove the free ligand. General effects such as steric hindrance or changes in electrostatic binding properties of the modified rFVIIa to its receptors are probably responsible for this impairment rather than a loss of specific recognition of the receptors, which could explain near normal activation of factor X by glycoPEGylated rFVIIa on TF expressing cells while its uptake is reduced.

Use of recombinant factor VIIa in a preterm infant with coagulopathy and subdural hematoma

Activated recombinant factor VIIa was administered to a preterm infant with bleeding diasthesis and a huge subdural hematoma that could not be controlled by the blood products. The coagulation tests were normalized the following day. Recombinant factor VIIa can be a choice in selected cases with intractable bleedings unesponsive to conventional replacement therapy.

Recombinant Activated Factor VII Following Pediatric Cardiac Surgery

Objective: Review the use of recombinant activated Factor VII following cardiac surgery. Specifically, we sought to define our current therapeutic practice indications and outcomes to assess the impact of recombinant activated factor VII on postoperative bleeding. Design: Retrospective case series. Setting: The study was conducted at the University affiliated pediatric intensive care unit. Patients and participants: All postcardiac surgical patients who received recombinant activated Factor VII between June 2002 and July 2006. Results: Cardiac surgery requiring cardiopulmonary bypass was performed on 1010 children during this period. In all, 25 (2.5%) children received recombinant activated factor VII for excessive bleeding. A single dose (180 μg/kg) of recombinant activated factor VII was given to 11 patients and 2 doses of 180 μg/kg to 14 patients. Intercostal drain losses were reduced from 12 (6.7-20.8) mL/kg/h to 3 (1-4.1) mL/kg/h, P = .018 following 1 dose of recombinant activated factor VII. In those receiving 2 doses; initial losses were 19.1 (7.5-31.7) mL/kg/h, after the first dose were 7.5 (3.6-13.7) mL/kg/h, P = .046, and after the second dose were 2 (1-2.9) mL/kg/h, P = .008. The plasma prothrombin time decreased in both the 1 dose, P = .003 and 2 dose, P = .009 groups. The activated partial thromboplastin time also decreased in the 1 dose group, P = .007 and 2 dose group, P = .03. There were no side effects attributable to recombinant activated factor VII. Annual rates of return to the operating theatre for excessive bleeding were coincidentally reduced in association with the routine use of recombinant activated factor VII from 4.3% to 1.5%, P = .019. Conclusions: Hemostasis occurred in 25 postoperative pediatric cardiac patients after recombinant activated Factor VII was given. In this setting, once conventional hemostatic therapy was optimized, recombinant activated Factor VII 180 μg/kg initially with intercostal losses greater than 10 mL/kg/h and a repeat dose after 2 hours if losses remained greater than 5 mL/kg/h was effective. No complications were found to have occurred and there was a coincidental reduction in annual returns to theatre for excessive bleeding.

Recombinant activated factor VII use in critically ill infants with active hemorrhage

INTRODUCTION

Recombinant activated factor VII (rFVIIa) is infrequently used off-label in infants despite a paucity of data in this population. We report a retrospective review of rFVIIa use in infants focusing on safety and efficacy.

METHOD

Between 2002 and 2007, 32 critically ill nonhemophiliac infants less than 1 year old received rFVIIa at our institution. Indications of rFVIIa and post-rFVIIa venous thrombosis were reviewed. Transfusion requirements were calculated 8 hours before and after rFVIIa administration.

RESULTS

Infants received on average 2 doses of rFVIIa at a mean dosage of 90 microg/kg. Active hemorrhage was the indication for rFVIIa in 24 infants, which included postoperative bleeding in 16 and nonsurgical bleeding in 8. The remaining 8 infants had preoperative coagulopathy. Thrombosis was noted in 4 infants (13%) and was not related to transfusion requirements, the number of doses, or dosage of rFVIIa. For infants who had active hemorrhage, rFVIIa was able to significantly reduce the requirements of packed red blood cells by 36.17 mL/kg (P < .005), platelets by 10.31 mL/kg (P < .01), and cryoprecipitates by 2.19 mL/kg (P < .05).

CONCLUSION

This is the first large case series demonstrating the efficacy of rFVIIa in critically ill infants with active hemorrhage by reducing their transfusion requirements. Furthermore, venous thrombosis was not associated with increase in either the number of doses or dosage of rFVIIa.

Single-dose recombinant activated factor VII therapy in hemophilia patients with inhibitors

Recombinant activated factor VII (rFVIIa; NovoSeven, Novo Nordisk, Bagsvaerd, Denmark) is well established as an effective hemostatic agent for the management of hemorrhage in hemophilia patients with inhibitors. Its use in prophylaxis is currently being investigated. On-demand treatment schedules usually involve multiple bolus doses of 90 to 120 microg/kg administered every 2 to 3 hours, but recent evidence from randomized controlled trials suggests that the use of higher single doses is equally safe and effective when used for the home treatment of hemarthroses. Consequently, the use of a single dose of 270 microg/kg rFVIIa for the treatment of bleeds in inhibitor patients has recently been approved by the European Medicines Agency (EMEA). Such high-dose regimens may overcome the rapid clearance rate observed in pediatric patients, and may be more convenient for patients with poor venous access. It also has been suggested that individually tailored single-dose therapies might be beneficial in selected groups of patients, although proper monitoring of such patients is advised. Further research should contribute towards more effective dose optimization of rFVIIa in hemophilic inhibitor patients.

Recombinant factor VIIa for intraoperative bleeding in a child with hepatoblastoma and review of recombinant activated factor VIIa use in children undergoing surgery

We report a case of a child with a large liver mass who underwent an open liver biopsy and had massive bleeding intraoperatively. Recombinant activated factor VII (rFVIIa) given intraoperatively was successful in stopping the bleeding. We also reviewed the literature on the use of rFVIIa in pediatric surgery.

The effect of tissue factor concentration on calibrated automated thrombography in the presence of inhibitor bypass agents

Thrombin generation has been suggested as a method to monitor treatment with factor eight inhibitor bypassing activity (FEIBA) or recombinant FVIIa (rFVIIa). The sensitivity of the assay for individual coagulation factors is dependent on the tissue factor (TF) concentration. An inverse relation between the rFVIIa concentration needed to shorten the clotting time and TF concentration has been shown but the data on thrombin generation are inconsistent. Information on TF concentration in measurements with FEIBA is limited. We studied the influence of TF concentration (1 and 5 pM) on thrombin generation through spiking experiments with rFVIIa and/or FEIBA in the plasma of severe haemophilia A patients and after four and three treatment episodes, respectively, using the calibrated automated thrombin generation assay (CAT) in platelet poor plasma. Spiking with FEIBA showed a linear relation with the endogenous thrombin potential (ETP)/peak at 1 pM but substrate depletion at 5 pM. Spiking with rFVIIa showed a near linear dose-response relation with the ETP/peak at 1 pm but only a shortening of the initiation phase at 5 pM. Similar effects were present in post-treatment samples. FEIBA acted synergistically with rFVIIa. This suggest a role for CAT in monitoring inhibitor bypass treatment but low TF concentrations are required to avoid substrate depletion with FEIBA and to demonstrate the effect of rFVIIa.

[Recombinant factor VIIa (rFVIIa). Description of use in a cohort of critical patients and prognostic markers]

OBJECTIVE

Describe and identify the factors associated with the survival of the patients who received treatment with rFVIIa in an Intensive Care Unit (ICU).

DESIGN

Longitudinal, ambispective, observational, descriptive study in a series of clinical cases performed from July 20, 2004 to July 20, 2006.

SCOPE

The study population included 16 hospitalized patients in the Intensive Medicine Department (ICU) of the Hospital Marqués de Valdecilla (Santander).

PATIENTS

Inclusion criteria were: Patients who required rFVIIa at some time of their stay in the ICU.

RESULTS

Hemodynamic improvement of the patients treated with rFVIIa in an ICU, within the first 3 hours of the infusion (evaluated by an increase of SBP > 20 mmHg and/or increase of DBP > 8 mmHg) was associated to greater survival.

CONCLUSIONS

The present series of cases, with the disadvantage of its heterogeneity and the limited number of patients, stresses the role of hemodynamic improvement as a differentiating factor between those patients who survive and those who do not.

The impact of major surgery on blood coagulation factors and thrombin generation

We studied the blood coagulation system of 14 patients with metastatic malignancies before and after they had undergone major surgery. In addition to measuring a battery of coagulation factors, we assessed the function of the system with assays of whole blood thrombin generation. With the exceptions of factor VIII (fVIII), which increased, and fibrinogen and fIX, which did not change, the activities of all the pro- and anticoagulant proteins were significantly lower postoperatively. However, the thrombin generating capacity of the system was relatively preserved. Although the integral of thrombin activity over time was lower after surgery, the mean peak thrombin concentration was unchanged and the time to clot formation was shortened. Similar changes could be reproduced by lowering the concentrations of pro- and anticoagulant factors together in control blood samples. Therefore, simultaneous reductions in pro- and anticoagulant proteins postoperatively worked to maintain the functional integrity of the blood coagulation system.

The intraoperative use of recombinant FVIIa in child with hemophilia A with antibodies

Patients with hemophilia A that developed inhibitors to FVIII represent a problem for bleeding control especially during surgical procedures. We report the use of bolus injections of rFVIIa during one intervention that included synoviectomy on the right knee, cholecystectomy and appendicectomy in a child with high titer of inhibitors to FVIII. rFVIIa was administered at the start (120 microg x kg(-1)) and then every 2 h (90 microg x kg(-1)) during the procedure. epsilon-aminocapronic acid was also administered as an antifibrinolytic every 3 h. We monitored aPTT (activated partial thromboplastin time) and PT (prothrombin time) and they were within reference values. Surgery lasted 7 h without significant hemorrhage. Postoperatively the dose of rFVIIa was slowly reduced and after ten days the patient was discharged home in good condition. In our case rFVIIa helped a child with hemophilia A with antibodies to undergo major surgery but each case should be treated individually and the cost of rFVIIa has also to be taken into account.

Successful treatment of severe gastrointestinal bleeding secondary to Crohn disease with recombinant factor VIIa

A 58-year-old man diagnosed with ileocolonic Crohn disease was admitted to the emergency room with massive lower gastrointestinal hemorrhage and hypovolemic shock. Treatment was started with methylprednisolone, metronidazole and omeprazole. Within the next 24 hours, he received a total of 9 U of red blood cell concentrate and 2 U of fresh frozen plasma. Because of persistence of bleeding, hypovolemic shock and life-threatening situation, we started therapy with rFVIIa. One dose of 120 microg/kg and another dose of 120 microg/kg three hours after the first dose were administered as compassionate use, with resolution of bleeding in the next 12 hours. On day 4 the patient was stabilized. We performed a total colonoscopy and intubation of the ileocecal valve that showed patchy deep ulcerations in the rectum with bleeding inflammatory pseudopolyps. Acute gastrointestinal bleeding is an unusual complication in Crohn disease. In this case, the use of recombinant activated factor VIIa controlled the massive gastrointestinal bleeding secondary to Crohn disease and without clinically significant adverse effect. There are few case reports documenting the use of recombinant activated factor VIIa for this type of off-label indication. Clinical trials should be carried out to define the dosage and dose interval schedule of rFVIIa in the treatment of uncontrolled massive gastrointestinal bleeding secondary to Crohn disease.

Recent developments in the pharmacologic approach to pediatric critical care

PURPOSE OF REVIEW

There is new information supporting a resurgence of targeted use of older medications. These therapies include hydrocortisone and vasopressin. In addition to these older drugs, newer drugs, drotrecogin alpha (activated protein C) and activated factor VII concentrate (NovoSeven), have been used and may improve outcome in the treatment of critically ill patients. This review summarizes the recent experience of these agents in the adult and pediatric critically ill populations.

RECENT FINDINGS

Preliminary findings are encouraging in selected septic children and adults for human recombinant activated protein C and protein C concentrate. Plasma vasopressin levels in pediatric septic shock and their importance have not yet been adequately studied. Recent evidence supports physiologic replacement of corticosteroids in specific adult populations. Further investigations are warranted to establish the role of activated factor VIIa in the treatment of critically ill children.

SUMMARY

The limited experience of protein C manipulation in critically ill septic pediatric patients makes it difficult to define its role in their care. Although it has been associated with improved outcomes, its risk profile warrants judicious use. Further prospective pediatric clinical trials are needed to define the role of vasopressin in the treatment of pediatric shock and cardiac arrest. The role of corticosteroids in the treatment of septic shock in adults and children continues to be debated. Activated factor VIIa administration to adult and pediatric patients without primary bleeding disorders has been increasing. Further investigations are warranted to establish the role of activated factor VIIa in the treatment of critically ill children.

Prophylactic and therapeutic use of recombinant activated factor VII in patients with cirrhosis and coagulation impairment

Patients with cirrhosis and impaired coagulation often pose major therapeutic problems during bleeding episodes or invasive procedures. Recombinant activated factor VII (rFVIIa), which has been licensed for the treatment of haemophilia patients with factor VIII or IX inhibitors, has been occasionally used in cirrhotic patients. We present five patients with cirrhosis and coagulopathy who received 1-4 recombinant activated factor VII infusions either prophylactically in order to safely undergo an invasive procedure or therapeutically in order to control a severe bleeding episode which did not respond to standard supportive care. In particular, recombinant activated factor VII infusions were given in two patients before a percutaneous liver biopsy, in one patient before teeth extraction and in two patients with haemoperitoneum after an invasive procedure. Infusions of recombinant activated factor VII achieved rapid correction of prothrombin time in all cases allowing the safe performance of invasive procedures or resulting in efficient control of the bleeding episode. In conclusion, recombinant activated factor VII seems to be a rather promising agent for the prevention or treatment of complications of haemostasis impairment in cirrhotic patients. However, its exact role in this setting needs to be evaluated within well-designed, controlled clinical trials.

Endothelial cell protein C receptor acts as a cellular receptor for factor VIIa on endothelium

Although factor VII/factor VIIa (FVII/FVIIa) is known to interact with many non-vascular cells, activated monocytes, and endothelial cells via its binding to tissue factor (TF), the interaction of FVII/FVIIa with unperturbed endothelium and the role of this interaction in clearing FVII/FVIIa from the circulation are unknown. To investigate this, in the present study we examined the binding of radiolabeled FVIIa to endothelial cells and its subsequent internalization. (125)I-FVIIa bound to non-stimulated human umbilical vein endothelial cells (HUVEC) in time- and dose-dependent manner. The binding is specific and independent of TF and negatively charged phospholipids. Protein C and monoclonal antibodies to endothelial cell protein C receptor (EPCR) blocked effectively (125)I-FVIIa binding to HUVEC. FVIIa binding to EPCR is confirmed by demonstrating a marked increase in (125)I-FVIIa binding to CHO cells that had been stably transfected with EPCR compared with the wild-type. Binding analysis revealed that FVII, FVIIa, protein C, and activated protein C (APC) bound to EPCR with similar affinity. FVIIa binding to EPCR failed to accelerate FVIIa activation of factor X or protease-activated receptors. FVIIa binding to EPCR was shown to facilitate FVIIa endocytosis. Pharmacological concentrations of FVIIa were found to impair partly the EPCR-dependent protein C activation and APC-mediated cell signaling. Overall, the present data provide convincing evidence that EPCR serves as a cellular binding site for FVII/FVIIa. Further studies are needed to evaluate the pathophysiological consequences and relevance of FVIIa binding to EPCR.

Human recombinant activated factor VII for upper gastrointestinal bleeding in patients with liver diseases

BACKGROUND

Mortality from upper gastrointestinal bleeding in patients with liver disease is high. The human recombinant activated factor VII is one of the suggested treatments for upper gastrointestinal bleeding in these patients.

OBJECTIVES

To assess the beneficial and harmful effects of human recombinant factor VIIa in patients with liver disease and upper gastrointestinal bleeding.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, ISI Web of Knowledge, and LILACS. The search strategies used are given in Table 01. We sought additional randomised trials from the reference lists of the trials and reviews identified through the electronic searches.

SELECTION CRITERIA

All randomised clinical trials irrespective of design, publication status, and language comparing human recombinant activated factor VII versus placebo, or any other control intervention for patients with liver disease and upper gastrointestinal bleeding, irrespectively of aetiology.

DATA COLLECTION AND ANALYSIS

We estimated relative risks (RR) for dichotomous outcomes and mean differences for continuous data. Since only one trial was identified, meta-analysis was not possible.

MAIN RESULTS

We included one trial with 242 adult patients. In this study, human recombinant activated factor VII administration did not reduce the risk of death (mortality within five days (RR 1.75, 95% confidence interval (CI) 0.53 to 5.82), and mortality within 42 days (RR 1.45, 95% CI 0.70 to 3.00)).

AUTHORS' CONCLUSIONS

We found no evidence that human recombinant activated factor VII reduces the risk of death in patients with liver disease and upper gastrointestinal bleeding. However, we made our conclusion on a single randomised clinical trial. More randomised clinical trials having low risk of bias are necessary in order to determine the role of human recombinant factor VIIa in clinical practice.