Prophylactic recombinant factor VIIa in haemophilia patients with inhibitors

Radiosynovectomy for the Treatment of Chronic Hemophilic Synovitis: An Old Technique, but Still Very Effective

A radiosynovectomy (RS) should be indicated when recurrent articular bleeds related to chronic hemophilia synovitis (CHS) exist, established by clinical examination, and confirmed by imaging techniques that cannot be constrained with hematological prophylaxis. RS can be performed at any point in life, mainly in adolescents (>13−14 years) and adults. Intraarticular injection (IAI) of a radioactive material in children might be arduous since we need child collaboration which might include general anesthesia. RS is our initial option for management of CHS. For the knee joint we prescribe Yttrium-90, while for the elbow and ankle we prescribe Rhenium-186 (1 to 3 IAIs every 6 months). The procedure is greatly cost efficient when compared to surgical synovectomy. Chemical synovectomy with rifampicin has been reported to be efficacious, inexpensive, simple, and especially practical in developing countries where radioactive materials are not easily available. Rifampicin seems to be more efficacious when it is utilized in small joints (elbows and ankles), than when utilized in bigger ones (knees). When RS and/or chemical synovectomy fail, arthroscopic synovectomy (or open synovectomy in some cases) should be indicated. For us, surgery must be performed after the failure of 3 RSs with 6-month interims. RS is an effective and minimally invasive intervention for treatment of repeated articular bleeds due to CHS. Although it has been published that the risk of cancer does not increase, and that the amount of radioactive material used in RS is insignificant, the issue of chromosomal and/or deoxyribonucleic acid (DNA) changes remains a concern and continued surveillance is critical. As child and adulthood prophylaxis becomes more global, RS might become obsolete in the long-term.

Increased Accumulation and Retention of rhFVIIa (eptacog beta) in Knee Joints of Hemophilia A Mice Compared to Wild-Type Mice

Our earlier studies showed that recombinant human factor VIIa (rhFVIIa) administered intravascularly in mice disappeared rapidly from the circulation. However, a small fraction of rhFVIIa that entered extravascular remained functionally active for an extended period. The present study aims to investigate the dose-dependency of rhFVIIa accumulation and retention in mouse knee joints and test whether the hemophilic condition affects rhFVIIa sequestration in joints. Wild-type and FVIII^-/- mice were injected with three doses of rhFVIIa (eptacog beta, 90, 250, and 500 μg/kg) via the tail vein. At varying times following rhFVIIa administration, blood and knee joints were collected to measure FVIIa activity and antigen levels in plasma and joint tissues. Joint tissue sections were analyzed by immunohistochemistry for the presence of rhFVIIa. Vascular permeability was assessed by either Evans Blue dye or fluorescein dextran extravasation. The study showed that rhFVIIa accumulated in knee joints of wild-type and FVIII^-/- mice in a dose-dependent manner. rhFVIIa antigen and FVIIa activity could be detectable in joints for at least 7 days. Significantly higher levels of rhFVIIa accumulation were observed in knee joints of FVIII^-/- mice compared with that of wild-type mice. Immunohistochemical analyses confirmed higher levels of rhFVIIa retention in FVIII^-/- mice compared with wild-type mice. Additional studies showed that FVIII^-/- mice were more permissible to vascular leakage. In conclusion, the present data demonstrate a dose-dependent accumulation of rhFVIIa in knee joints, and the hemophilic condition enhances the entry of rhFVIIa from circulation to the extravascular. The present data will be useful in improving rhFVIIa prophylaxis.

Decreasing the need for transfusion: infant cardiac surgery using hemodilution and recombinant factor VIIa

Many strategies, including intraoperative acute normovolemic hemodilution (ANH) and pharmacologic agents, exist to minimize the use of allogeneic blood products in pediatric congenital heart surgery. Recombinant activated factor VIIa (rFVIIa) is a hemostatic agent approved for the treatment of bleeding episodes and prevention of bleeding in surgical interventions in patients with hemophilia A or B with inhibitors, acquired hemophilia, or congenital factor VII deficiency. Off-label use in nonhemophilic patients for uncontrolled hemorrhage is increasing although still under investigation. We present our experience with ANH and rFVIIa in nine patients. All were <16 months of age and underwent complex cardiac surgery with the end point of achieving hemostasis while decreasing or eliminating the need for allogeneic blood products. Clinically, we have observed rapid hemostasis in patients who underwent ANH and then had autologous blood reinfused after cardiopulmonary bypass, along with rFVIIa, without any time delay. The patients required no allogeneic blood products and therefore results suggested the potential utility of this practice. The study group consisted of nine patients <16 months of age who received rFVIIa in the operating room after open-heart surgery. Amount of autologous blood removed preoperatively, blood product use, time from protamine to rFVIIa administration, platelet count, INR, and fibrinogen level were retrospectively obtained. Of the nine patients, the three who underwent the most aggressive hemodilution received rFVIIa most rapidly and required no allogeneic blood products to achieve hemostasis although they had an average lower fibrinogen level on admission to the cardiothoracic intensive care unit. These preliminary data suggest that hemodilution before surgical stimulation and the rapid administration of rFVIIa, along with the reintroduction of autologous blood, may decrease or potentially eliminate the need for allogeneic blood products. Prospective trials are warranted to further explore this technique.

Capturing daily assessments and home treatment of congenital hemophilia with inhibitors: design, disposition, and implications of the Dosing Observational Study in Hemophilia (DOSE)

OBJECTIVE

The daily recordings of treatment by patients with congenital hemophilia with inhibitors and their caregivers were assessed as part of the Dosing Observational Study in Hemophilia (DOSE) to understand the patterns of bypassing agent use and health-related quality of life.

METHODS

Frequently bleeding patients prescribed recombinant activated factor VII as first-line therapy were eligible. Participants recorded daily paper diaries for at least 90 days and until at least four bleeding episodes had occurred. Web-based entry was optional. Assessment included bleeding status, work or school day status, bleeding episode, treatment, impact on planned activities, and health-related quality of life.

RESULTS

Diaries were completed by 18 adults and 19 caregivers (21 children). A total of 4063 diary days and 194 bleeding episodes over 491 bleed days were recorded. A small proportion of diary days were bleed days (8.2%) or treatment days (8.2%). Half the bleed days were not planned work or school days for patients (53%) or caregivers (48%). An exact agreement was observed between electronic and paper records for 93% of the reviewed health-related quality of life measurements.

CONCLUSION

Daily diary completion by patients and caregivers is feasible and provides insight into the impact of congenital hemophilia with inhibitors on daily activities and overall quality of life. Positive participation and completion rates were supported by frequent patient contact made by independent patient support liaison personnel.

Endothelial cell protein C receptor-mediated redistribution and tissue-level accumulation of factor VIIa

BACKGROUND

Recent studies show that activated factor VII (FVIIa) binds to the endothelial cell protein C receptor (EPCR) on the vascular endothelium; however, the importance of this interaction in hemostasis or pathophysiology is unknown.

OBJECTIVE

The aim of the present study was to investigate the role of the FVIIa interaction with EPCR on the endothelium in mediating FVIIa transport from the circulation to extravascular tissues.

METHODS

Wild-type, EPCR-deficient or ECPR-over-expressing mice were injected with human recombinant (r)FVIIa (120 μg kg(-1) body weight) via the tail vein. At varying time intervals after rFVIIa administration, blood and various tissues were collected to measure FVIIa antigen and activity levels. Tissue sections were analyzed by immunohistochemistry for FVIIa and EPCR.

RESULTS

The data reveal that, after intravenous (i.v.) injection, rFVIIa rapidly disappears from the blood and associates with the endothelium in an EPCR-dependent manner. Immunohistochemical analyses revealed that the association of FVIIa with the endothelium was maximal at 30 min and thereafter progressively declined. The FVIIa association with the endothelium was undetectable at time points exceeding 24 h post-FVIIa administration. The levels of rFVIIa accumulated in tissue correlate with expression levels of EPCR in mice and FVIIa associated with tissues remained functionally active for periods of at least 7 days.

CONCLUSIONS

The observation that an EPCR-dependent association of FVIIa with the endothelium is most pronounced soon after rFVIIa administration and subsequently declines temporally, combined with the retention of functionally active FVIIa in tissue homogenates for extended periods, indicates that FVIIa binding to EPCR on the endothelium facilitates the transport of FVIIa from circulation to extravascular tissues where TF resides.

Physician preferences for medication attributes for the prophylactic treatment of patients with severe haemophilia A with inhibitors to factor VIII

Prophylaxis may be beneficial for patients with severe haemophilia A who have developed inhibitors to factor VIII. The aim of this study was to determine physicians' preferences for medication attributes in the prophylactic treatment of this patient population. Haematologists from Europe (EU) and the United States (US) participated in a discrete choice exercise to explore their preferences for medication attributes (efficacy, cost, scientific evidence, dosing frequency and administration time) associated with prophylaxis for severe haemophilia A in patients with inhibitors to factor VIII. Physicians' preferences for medication attributes were assessed through completion of 25 trade-off tasks that included a choice between two hypothetical medications each comprised of one randomized level of each medication attribute. Participants also completed a sociodemographic questionnaire. Data were analysed using a random effects logit model. Participants (N = 36: US = 19; EU = 17) were 80.6% men, had a mean of 19.8 years (SD ± 8.1) [range 6-35] of practice experience. The physicians treated an average of 5.7 (± 5.5) patients with severe haemophilia A and inhibitors per month and reported treating 36.2% of these patients prophylactically. The most important medication attributes for prophylactic treatment were efficacy [Relative Importance (RI) = 35.0%] and scientific evidence (RI = 34.1%), whereas treatment cost (12.0%), dosing frequency (10.8%) and administration time (8.2%) were less important. Results were similar across the EU and US. Efficacy and scientific evidence are the primary considerations for physicians' choice of prophylactic medications for use in this patient population.

Safety and pharmacokinetics of a glycoPEGylated recombinant activated factor VII derivative: a randomized first human dose trial in healthy subjects

BACKGROUND

Extensive research is currently ongoing to prolong the half-life of coagulation factors. One of these techniques is glycoPEGylation, which has also been applied to recombinant activated factor VII (rFVIIa), resulting in a rFVIIa derivative (N7-GP) with a prolonged terminal half-life (t(1/2) ). The main clinical purpose of N7-GP is to provide safe and effective prophylaxis to patients with hemophilia and inhibitors. The prolonged t(1/2) of N7-GP can potentially reduce the dosing frequency and thereby facilitate convenience and compliance, which are two significant barriers to effective prophylaxis.

OBJECTIVES

To determine the safety and pharmacokinetics of single doses of N7-GP in healthy men.

METHODS

 A randomized, placebo-controlled, dose-escalation trial with five cohorts (N7-GP dose of 12.5-100 μg kg(-1) ) was performed. In each cohort, eight subjects were randomized to receive N7-GP (n = 6) or placebo (n = 2).

RESULTS

The mean FVIIa activity was measurable for up to at least 72 h after dosing, and the overall mean t(1/2) for FVIIa activity was 15 h. The pharmacokinetics of N7-GP appeared to be dose-proportional in the dose range investigated. No serious adverse events (including thromboembolic events) were reported. The frequency of adverse events was similar in both the placebo and N7-GP groups. No neutralizing antibodies against N7-GP were detected. A pharmacologic effect was apparent from a dose-dependent statistically significant decrease in the mean prothrombin time in all N7-GP groups as compared with placebo.

CONCLUSIONS

 N7-GP had a plasma half-life of 15 h and a profile that makes it a potential candidate for prophylaxis in patients with hemophilia and inhibitors.

Current difficulties and recent advances in bypass therapy for the management of hemophilia with inhibitors: a new and practical formulation of recombinant factor VIIa

Bypassing agents are the mainstay of treatment for patients with hemophilia with high-titer inhibitors. Whereas the availability of these agents has greatly advanced the management of bleeding episodes in this population, timely administration of bypassing agents continues to be hampered by a number of practical limitations, including the need for refrigerated storage of the agent and its reconstitution at room temperature prior to administration, among others. In this review, the importance of early treatment of bleeds and factors that influence this more timely therapeutic approach are highlighted, together with the advantages offered by the use of a new formulation of recombinant activated factor VII that permits improved storage and portability, potentially optimizing timely bypassing agent administration.

When should prophylaxis therapy in inhibitor patients be considered?

Currently, patients with severe haemophilia can expect to lead a relatively normal life including prevention of disabling arthropathy as a result of the development of factor replacement therapy and advances in the understanding of the use of such therapy given prophylactically. Unfortunately, a subset of patients develops neutralizing antibodies termed inhibitors rendering such therapy ineffective. These patients frequently develop recurrent joint bleeding resulting in arthropathy. Until recently, prophylactic therapy was not considered for patients with inhibitors because of the perceived lack of an effective therapeutic agent. However, an accumulation of case reports and a recent prospective study have suggested that prophylaxis with the currently available bypassing agents could be effective and appears to be safe in selected cases. This report will review the current data on prophylaxis with bypassing agents and suggest specific situations in which prophylaxis in inhibitor patients could be considered.

First 20 years with recombinant FVIIa (NovoSeven)

This review describes the background for the development of recombinant FVIIa (rFVIIa; NovoSeven) for use in haemophilic patients with inhibitors. The first proof of principle for using pharmacological doses of FVIIa as a haemostatic agent was obtained by producing small amounts of pure plasma-derived FVIIa, which showed encouraging effect in two patients with haemophilia A and inhibitors. To make pure FVIIa available for use in a larger number of patients, rFVIIa was produced that was approved for use in patients with inhibitors against coagulation factors (congenital haemophilia and acquired haemophilia) in 1996 (EU), 1999 (USA) and 2000 (Japan). The efficacy rate in severe bleedings and in major surgery including major orthopaedic surgery has been found to be around 90% in controlled studies, and no serious safety concerns have been demonstrated. The availability of rFVIIa has facilitated the performance of elective major surgery in haemophilia patients with inhibitors. Further steps along the vision of providing a treatment for inhibitor patients similar to non-inhibitor patients have been the efficacy of rFVIIa in home-treatment and recently the encouraging experience in prophylaxis. The concept of using pharmacological doses of rFVIIa as a haemostatic agent is a new one, which has caused difficulties in finding the correct dose. A step forward has been the demonstration that similar efficacy can be achieved after one single dose of 270 μg kg(-1) instead of three injections of a dose of 90 μg kg(-1). The higher clearance rate in children suggests that higher doses may be beneficial in children. The availability of rFVIIa has made advances in the understanding of coagulation processes possible. In a cell-based in vitro model, it has been shown that rFVIIa binds to preactivated platelets if present in concentrations of 30 nm or higher. By doing so, it activates FX into FXa and enhances the thrombin generation on the activated platelet surface in the absence of FVIII/FIX. Through the increased thrombin generation, a firm, well-structured fibrin haemostatic plug, which is resistant to premature lysis, is formed. By exploiting this mechanism of action, rFVIIa may also be effective in situations other than haemophilia, characterized by an impaired thrombin generation.

Clinical issues in inhibitors

SUMMARY

Anamestic inhibitors represent the major complication of haemophilia therapy now that clotting factor concentrates are virtually free of pathogen-transmission risk. Conventional clotting factor replacement is usually insufficient to prevent or treat bleeding in a haemophilia patient with a high responding inhibitor so that alternative treatment with bypassing agents is required. Despite their relative efficacy, their use does not achieve the same invariable haemostasis that patients without inhibitors do following treatment with factor concentrate replacement. This has led to the attempt to eradicate such inhibitors with immune tolerance induction. Success is not invariable, however, and many patients with long-term persistent high-titre inhibitors continue to experience great morbidity. Recently, this has given rise on a limited basis to attempts to use bypassing agents in prophylaxis regimens in an effort to alleviate this extreme morbidity. Each of these strategies is discussed in the context of their relative benefits and risks.

Recurrent miscarriage and antiphospholipid antibodies: prognosis of subsequent pregnancy

BACKGROUND

 Although women with antiphospholipid antibodies (APLAs) are at increased risk of recurrent miscarriage, the outcome of a subsequent pregnancy is not clearly elucidated.

OBJECTIVES

To assess the pregnancy outcome of a subsequent pregnancy in women with APLAs and compare this outcome with women with unexplained recurrent miscarriage.

METHODS

 We performed a cohort study among all women who attended the Miscarriage Clinic at Liverpool Women's Hospital between 1987 and 2006 after being referred due to recurrent miscarriage (≥2 consecutive pregnancy losses). All women underwent a standardized investigation sequence. Women with other reasons for recurrent miscarriage were excluded.

RESULTS

 A total of 693 women fulfilled the selection criteria, of whom 176 (25%) had APLAs. One hundred and twenty-two (69%) women with APLAs had a subsequent live birth compared with 324 (63%) women with unexplained recurrent miscarriage (OR 1.3, 95% CI 0.9-1.9). No differences were found for birth weight, gestational age, and intra-uterine growth restriction. When treatment was analyzed, 53/67 (79%) of women with APLAs who had received aspirin and heparin during their pregnancy had a live birth, compared with 64/104 (62%) of women with APLAs who received aspirin only (adjusted OR 2.7, 95% CI 1.3-5.8). In unexplained recurrent miscarriage, stratification for treatment showed no differences in outcome.

CONCLUSION

The prognosis of a subsequent pregnancy in women with APLAs is good. Although this was not a randomized clinical trial, combined treatment of aspirin and heparin seemed associated with a better outcome in women with APLAs, but not in women with unexplained recurrent miscarriage.

Evidence supporting the use of recombinant activated factor VII in congenital bleeding disorders

BACKGROUND

Recombinant activated factor VII (rFVIIa, NovoSeven) was introduced in 1996 for the treatment of hemophilic patients with antibodies against coagulation factor VIII or IX.

OBJECTIVE

To review the evidence supporting the use of rFVIIa for the treatment of patients with congenital bleeding disorders.

PATIENTS AND METHODS

English-language databases were searched in September 2009 for reports of randomized controlled trials (RCTs) evaluating the ability of rFVIIa to restore hemostasis in patients with congenital bleeding disorders.

RESULTS

Eight RCTs involving 256 hemophilic patients with antibodies against coagulation factors, also known as inhibitors, were identified. The evidence supporting the use of rFVIIa in these patients was weak with regard to dose, clinical setting, mode of administration, efficacy, and adverse events, given the limited sample size of each RCT and the heterogeneity of the studies.

CONCLUSION

The authors suggest that rFVIIa therapy in hemophilic patients with inhibitors should be based on the individual's ability to generate thrombin and form a clot, and not on the patient's weight alone. Therefore, assays for thrombin generation, such as whole-blood thromboelastography, have the potential to significantly improve the treatment of these patients.

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.

Paediatric haemophilia with inhibitors: existing management options, treatment gaps and unmet needs

Development of inhibitors is a severe complication of haemophilia posing many management challenges. While a long-term goal in inhibitor patients is eradication of inhibitors through immune tolerance induction, bypassing agents such as recombinant activated factor VII (rFVIIa) and activated prothrombin complex concentrate (aPCC) are essential for control of bleeding episodes. Paediatric patients with haemophilia and inhibitors are at particular risk of recurrent haemarthroses, and management of these patients should seek to avoid joint damage and support the child's full social and physical development. Current options for management of bleeding complications include on-demand treatment of acute bleeding episodes, secondary prophylaxis to avoid recurrent bleeds and surgery to treat affected joints. There is also a rationale for adopting prophylactic approaches to prevent bleeding in inhibitor patients, allowing this group similar opportunities for protection against arthropathy development as are given to non-inhibitor patients. This paper, based on a roundtable meeting of haematology experts at the first Zürich Haemophilia Forum in May 2008, reviews the current evidence supporting more intense and prophylactic approaches to manage bleeding risk in paediatric haemophilia patients with inhibitors, and highlights the need for investigations of primary prophylaxis in this vulnerable patient group, to support best long-term outcome.

Critical appraisal of the role of recombinant activated factor VII in the treatment of hemophilia patients with inhibitors

Hemophilia patients with inhibitors faced the constraint of inadequate treatment for several years before the era of recombinant factor VIIa (rFVII). Initially, rFVIIa was used in the compassionate-use programs. After a worldwide license was issued, more than 1.5 million doses were administered. Bleeding of joints and muscles was controlled effectively by means of an early home treatment program, with either a standard dose of 90 μg/kg every 2 to 3 hours for a few doses or a single dose of 270 μg/kg. For more serious bleeding episodes or minor surgery, an initial dose of 90 μg/kg was given every 2 hours for 24 to 48 hours followed by increased intervals of 3 to 6 hours according to the severity of bleeding and efficacy of bleeding control. In cases of major surgery such as orthopedic procedures, the same regimen can be applied except for a higher initial dose of 120 to 180 μg/kg. However, increasing the dose should be considered if there are unexpected bleeding complications since the half-life and clearance of rFVIIa differ between individuals. In addition, prophylaxis is administered to a small number of patients. Finally, the reported thromboembolic events found in hemophilia patients with inhibitors receiving rFVIIa are extremely low, much less than 1%.

Animal models of FVIIa gene expression: their role in the future development of haemophilia treatment

The development of inhibitors to replacement factor therapy is a serious complication in the treatment of patients with haemophilia and requires use of bypassing agents to prevent uncontrolled bleeding. The efficacy of recombinant factor VIIa (rFVIIa) as a bypassing agent in patients with haemophilia has been demonstrated in case studies and clinical trials. However, the perception of a short plasma half-life and consequent need for repeated daily injections means that long-term prophylaxis could potentially be limiting. Canine haemophilia models using a gene transfer approach have been used to evaluate the continuous expression of FVIIa in dogs. These studies show improvement in measurable bleeding parameters that have important clinical ramifications for patients with haemophilia. The combination of gene transfer as the method of delivery and FVII as the transgene overcomes issues associated with the short plasma half-life of rFVIIa, and represents a potentially attractive novel approach to haemostasis in patients with haemophilia and other platelet disorders.

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.

Prophylaxis in 10 patients with severe haemophilia A and inhibitor: different approaches for different clinical situations

The effect of bypassing agents is not as predictable as replacement therapy with the deficient factor in inhibitor patients. Consequently, these patients have more levels of arthropathy than patients without inhibitors. Prophylaxis for inhibitor patients has gained attention over the last decade and some papers have reported that bypassing agents could work in the prevention of arthropathy. However, there is a lack data to support any specific agent or regimen or even to recommend their use in different clinical conditions. We report ten patients with haemophilia A and inhibitors treated prophylacticaly with bypassing agents (5 with FEIBA and 5 with NovoSeven). The variable conditioning the choice of one agent or the other was the intention to initiate of immune tolerance induction therapy (ITI) in the future. In 8/10 patients (4 in FEIBA group and 4 in rFVIIa group) there was a decrease of bleeding episodes while 9/10 maintained or increased their joint range of motion (ROM). In the rFVIIa prophylaxis group, prophylaxis can be considered primary since all of them had had less than one joint bleed before prophylaxis. Economic analysis showed that prophylaxis is an expensive treatment. In our experience both agents seem to be safe and effective in reducing the number of bleeds in patients with inhibitors. The anamnestic response provoked by FEIBA could be an issue while awaiting a decline in titres before ITI can be initiated and so rFVIIa may be the best option for prophylaxis in patients with inhibitors who have not yet begun ITI.

Prevention of arthropathy: may it be extrapolated from patients without inhibitors to patients with inhibitors?

Although no consensus on the exact dosing schedule of prophylaxis in non-inhibitor haemophilia patients has been achieved, regular administration of factor VIII (FVIII) or factor IX (FIX) concentrates is currently accepted as the most effective treatment model in order to prevent sick days, hospital stays and the development of arthropathy in patients with severe haemophilia. The basis for prophylaxis has been the idea to increase the plasma levels of FVIII or FIX above 1% thereby improving the haemostasis in severe haemophilia. Current treatment in haemophilia patients with inhibitors includes the use of activated prothrombin complex concentrates and recombinant FVIIa (rFVIIa). Regular administration of such agents has recently repeatedly been reported to decrease the number of joint and muscle bleeds in these patients. Regarding rFVIIa, such an effect was confirmed in a controlled study published in 2007. Although the exact mechanism of action of rFVIIa in this setting is still not clear, it seems reasonable to assume that prophylaxis with rFVIIa will be able to prevent or minimize the development of haemophilic arthropathy. As arthropathy is a long-term complication in haemophilia and the result of repeated joint bleeds, a longer follow-up of patients on regular prophylaxis including measurements of the joint scores, as has been performed in FVIII/FIX prophylaxis in non-inhibitor patients, will be required for a definite conclusion.

Surgical complications in a hemophilia patient with factor VIII inhibitor and their endovascular management

Hemophilia, an X-linked disorder due to clotting factors VIII or IX deficiency, is associated with recurrent hemorrhage into joints, soft tissue, and organs. Recombinant factor VIII concentrates are available for the treatment of bleeding complications. However, inhibitors to factor VIII develop in 25% to 35% of patients with severe hemophilia A, making the management of bleeding episodes more complex. The treatment of unusual metachronous ruptured aneurysms in a patient with hemophilia A with factor VIII inhibitor is presented, and the outcomes of endovascular and open operations are discussed.

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.

Randomized, prospective clinical trial of recombinant factor VIIa for secondary prophylaxis in hemophilia patients with inhibitors

BACKGROUND

Hemophilic patients with factor VIII (FVIII) and FIX inhibitors suffer from frequent bleeding episodes and reduced quality of life.

OBJECTIVES

To evaluate whether secondary prophylaxis with activated recombinant factor VII (rFVIIa) can safely and effectively reduce bleeding frequency as compared to conventional on-demand therapy.

METHODS

Thirty-eight male patients entered a 3-month preprophylaxis period to confirm high baseline bleeding frequency (mean > or = 4 bleeds per month). Twenty-two patients were randomized 1:1 to receive daily rFVIIa prophylaxis with either 90 or 270 microg kg(-1) for 3 months, followed by a 3-month postprophylaxis period.

RESULTS

Bleeding frequency was reduced by 45% and 59% during prophylaxis with 90 and 270 microg kg(-1), respectively (P < 0.0001); however, there was no significant difference detected between doses. The majority of this reduction was maintained during the postprophylaxis period. Although all types of bleed were similarly reduced, the effect was most pronounced for spontaneous joint bleeds. Patients reported significantly fewer hospital admissions and days absent from work/school during prophylaxis as compared to the preprophylaxis period. No thromboembolic events were reported during prophylaxis.

CONCLUSION

Clinically relevant reductions in bleeding frequency during prophylaxis as compared to conventional on-demand therapy were achieved without raising safety concerns. These results provide evidence for the concept of secondary rFVIIa prophylaxis in inhibitor patients with frequent bleeds.

Prophylactic treatment of haemophilia patients with inhibitors: clinical experience with recombinant factor VIIa in European Haemophilia Centres

Many patients with haemophilia develop inhibitors to factor VIII and require bypassing agents to provide haemostatic cover for limb- or life-threatening bleeding episodes. Due to the reduced risk of blood-borne pathogen transmission with recombinant products, on-demand recombinant factor VIIa (rFVIIa; NovoSeven is the treatment of choice for children with inhibitors. In haemophiliac patients without inhibitors, primary prophylaxis has been clinical practice for several years. This paper summarises 13 case histories of rFVIIa secondary prophylaxis for haemophilia patients with inhibitors. This was a retrospective survey of adult and paediatric severe haemophilia patients with inhibitors treated with rFVIIa from ten European Haemophilia Centres. There was a wide variation in administered rFVIIa dose, from 200-250 microg kg(-1) per week to 220 microg kg(-1) daily. In many cases, this was lower than the recommended on-demand dose of rFVIIa. In 12/13 cases, prophylaxis with rFVIIa considerably reduced the number of bleeding episodes compared with previous treatment. Eight/nine patients were satisfied or very satisfied with rFVIIa treatment, and in cases reporting subjective quality of life (QoL), all were improved, much improved, or significantly improved. In haemophilia patients with inhibitors, prophylaxis with rFVIIa is highly effective in reducing the number of bleeding episodes and results in good patient compliance and improved QoL. Randomised controlled trials are needed to confirm these findings. Results of a recently completed clinical trial on secondary prophylaxis with rFVIIa in frequently bleeding haemophilia patients with inhibitors are expected in late 2006.

Prophylaxis in haemophilia patients with inhibitors

The presence of high titre inhibitors makes the treatment of bleeding episodes in haemophilia patients difficult and increases the risk of uncontrollable bleeding and disability, despite optimum on-demand treatment with bypassing agents. The inability to effectively control joint bleeding leads to progressive joint disease in many patients with inhibitors. Significant mobility impairments are far more prevalent in patients with inhibitors than in those without inhibitors. Emerging data suggest that prophylaxis using bypassing agents may be effective and safe in reducing the incidence of joint bleeding during immune tolerance induction (ITI), and for patients who failed ITI or who were never candidates for ITI. Only controlled clinical trials will ultimately demonstrate whether prophylaxis can prevent joint bleeding and damage, and improve quality of life in patients with inhibitors. This article will review the published data on the use of bypassing agents in the prevention of bleeding, and will discuss ongoing clinical prophylaxis trials in inhibitor patients.