Bleeding Episodes In Haemophilia Patients Research Articles

Analysis of Macrophage Migration Inhibitory Factor Genotype in Hemophilia a Patients.

Hemophilia A, an X-linked bleeding disorder, is caused by a complete or partial deficiency in factor VIII. Multiple factors engage in the development and progression of bleeding episodes in hemophilia patients, especially arthropathy. Detection of macrophage migration inhibitory factor (MIF)-173 G/C polymorphism in people with hemophilia A (PWH) and the possible associations between the type of MIF gene polymorphism and selected disease-related variables. This case-control study included 95 male patients with hemophilia A and 95 non-hemophiliac subjects, all aged from 2 months to 63 years. An allele-specific polymerase chain reaction (AS-PCR) with a multiplex technique was used to detect MIF polymorphisms. A significantly higher frequency of GG polymorphism was reported in the control group (81, 85.3%) compared to PWH (64, 67.4%), while a significantly higher frequency of GC polymorphism was found in PWH (21, 22.1%) than that in healthy subjects (10, 10.5%), P < 0.05. The G allele polymorphism was detected in 90.0% of the control group compared to 78.4% of PWH (149 subjects), while the C allele frequency was higher in PWH (41, 21.6%) compared to that in healthy individuals (18, 10.0%), P < 0.05. The frequencies of varied MIF-173 polymorphisms did not show significant differences among patients with different clinical presentations or in relation to presence of inhibitors, P > 0.05. MIF-173 GC polymorphism is seen in PWH more than that in healthy individuals. Further studies are required to detect additional SNPs through sequencing of the MIF gene and to detect MIF serum levels during bleeding episodes.

POSC395 Pharmacoeconomic Analysis of rFVIIa Versus PCC in the Treatment of Minor-to-Moderate Bleeds in Hemophilia Patients with Inhibitors in China

In China, treatment options for bleeding episodes in hemophilia patients with inhibitors most often involve recombinant factor VIIa (rFⅦa) or prothrombin-complex concentrate (PCC).The aim of this study was to compare the cost and effectiveness of two most commonly used treatment regimens : rFⅦa followed by PCC (rFⅦa - PCC) and PCC followed by rFⅦa (PCC - rFⅦa) for the treatment of minor-to-moderate bleeds in hemophilia patients with inhibitors.

Knowledge, attitude and practice of health care providers toward prescribing factor replacement at federally funded haemophilia treatment centres in the United States

Abstract Factor replacement is currently the standard of care to prevent or treat bleeding episodes in haemophilia patients. This study examined current prescribing practices of factor therapy for patients at haemophilia treatment centres (HTCs) in the United States. Aims The aims were to evaluate the driving forces for prescribing factor products, to evaluate current attitudes and knowledge toward factor product and industry, and to discuss the implications for health care providers in practice. Methods An anonymous electronic survey was distributed to 744 HTC health care providers (HCPs); 118 responses were analysed. Results The most common driving force for HCPs to change a patient's factor product was poor response to current therapy, while the most common perception of patients’ motivation to switch products was the potential for fewer infusions. HCPs with strong influence over the prescribed therapy identified inadequate pharmacokinetic (PK) studies as an important driving force; patients/caregivers perceived as having a strong influence over which therapy is prescribed selected less frequent dosing as an important motivator. HCPs who allow patients/caregivers to have a strong influence over which factor is prescribed were more likely to cite patient/caregiver request as a significant driving force for change in therapy. Conclusion The haemophilia treatment landscape continues to evolve and is becoming increasingly complex. The multitude of treatment options available now offer choices, presenting a need to focus on patient-centric prophylaxis.

Perioperative safety and haematostatic efficacy of a new bypassing agent pd-FVIIa/FX (Byclot) in haemophilia patients with high-responding type inhibitors.

: The novel agent pd-FVIIa/FX is a 1 : 10 protein weight mixture of activated factor VII (FVIIa) and factor X (FX) derived from donated blood plasma. A phase III clinical trial of pd-FVIIa/FX revealed high efficacy for bleeding episodes in haemophilia patients with inhibitors. However, up to now, only one case of this new agent being used for surgery had been reported. The objective of this study is to evaluate the perioperative haemostatic efficacy and safety of pd-FVIIa/FX in haemophilia patients with inhibitors. We retrospectively reviewed 25 operation charts from 14 haemophilia patients with high-responding inhibitors using pd-FVIIa/FX during the perioperative period. Efficacy was evaluated by attending physicians and results divided into four groups (excellent, good, fair, and poor). The operation chart was provided by nine Japanese medical institutes with expertise in haemophilia management. Out of the total of 25 surgical procedures, 44% (11/25) were classified as major surgery and the remainders were minor surgeries. In all of the surgeries but one, rFVIIa and/or APCC were administered in combination or sequential method. In all cases except one, the haemostatic efficiency rate was judged as excellent or good by treating physicians for an overall efficacy rate of 96%. No thrombotic adverse effects were reported. This study's results suggest that both combination and sequential therapy of pd-FVIIa/FX and other bypassing agents are well tolerated and effective for the control of perioperative bleeding in haemophilia patients with high-responding inhibitors.

Recombinant factor VIIa and prothrombin complex concentrates to treat bleeding episodes in hemophilic patients with inhibitors: a Systematic Review

Recombinant factor VIIa and prothrombin complex concentrates to treat bleeding episodes in hemophilic patients with inhibitors: a Systematic Review

Abdominal Compartment Syndrome in a Patient with Hemophilia A with a High Titer Inhibitor after a Minor Trauma

Abdominal compartment syndrome (ACS) is a life-threatening condition which can occur in patients with hemophilia although they have trivial traumas. Hemostatic control for bleeding episodes in hemophilia patients with inhibitors is difficult particularly when the availability of bypassing agents, recombinant activated factor VII (rFVIIa) and activated prothrombin complex concentrate (APCC), is constrained. Plasma exchange with continuous infusion of factor concentrate has been reported as a life-saving intervention in these patients. We reported a teenager with severe hemophilia A and a high-titer inhibitor who underwent two surgeries for ACS which developed after a minor trauma. Computerized tomography angiogram (CTA) of abdomen revealed a large pelvic hematoma and a bleeding from the sigmoidal artery. He underwent an abdominal angiography followed by the first surgery to relieve the ACS, and the second surgery for abdominal closure. The patients received plasma exchange with cryo-removed plasma peri-operatively. High-dose factor VIII (FVIII) concentrate (100 U/kg) was started after plasma exchange followed by continuous infusion at the rate 14 units/kg/hour for 7 days. rFVIIa and APCC concomitant with tranexamic acid were used for breakthrough bleeding. He received six times of plasma exchange, three doses of rFVIIa and five doses of APCC. Bleeding was successfully stopped and the titers of inhibitor decreased from the maximum of 4,400 BU to 3,680 BU. Plasma exchange and continuous FVIII infusion can be considered as an option for life-threatening hemorrhage in hemophilia patients with high-titer inhibitors in the countries where an access to bypassing agents is limited.

Enhanced Pharmacokinetics of Factor VIIa as a Monomeric Fc Fusion

Recombinant Factor VIIa (rFVIIa) is utilized for on-demand treatment of bleeding episodes in hemophilia patients with neutralizing antibodies (inhibitors) against Factor VIII or Factor IX, but a short half-life in the circulation (~2.5hrs) limits its use in a prophylactic setting. Recombinant FVIIa variants with improved pharmacokinetic properties may enable improved treatment and prevention of bleeding episodes in the inhibitor population. In this study we describe recombinant FVIIaFc (rFVIIaFc), a recombinant Fc-fusion protein generated to utilize the neonatal Fc receptor (FcRn)-mediated recycling pathway that protects immunoglobulin G from catabolism. On the basis of activity, rFVIIaFc exhibited a 5.5-fold extension in terminal half-life in hemophilia A mice compared to rFVIIa. The potency of rFVIIaFc was comparable to that of rFVIIa in thrombin generation assay and ROTEM. In agreement with these data, rFVIIaFc and rFVIIa showed similar acute efficacy at comparable molar doses in the tail clip bleeding model in hemophilia A mice. Taken together, these studies demonstrate enhanced pharmacokinetics and similar hemostatic properties for rFVIIaFc compared to rFVIIa.

Use of Recombinant Factor VIIA as a Risk Factor for Graft Loss after Orthotopic Liver Transplantation Due to Hepatic Artery Thrombosis

Background: The genetically engineered recombinant activated factor VII (rFVIIa) was primarily developed for the treatment of bleeding episodes in haemophilia patients with inhibitors. Different outcomes have been described in a number of studies evaluating the off-label use in patients with liver disease and consequently with complex coagulopathies. We here evaluated the use of rFVIIa in patients undergoing orthotopic liver transplantation (OLT). The aim of this study was to determine the safety within this patient population. Methods: Overall, 1343 OLTs were performed at Hannover Medical School between 2002 and 2014. Out of this group we selected patients having received rFVIIa in the early phase after OLT. We retrospectively analyzed the outcome of patients treated with rFVIIa and compared our findings to those from other transplant centers. Results: In a single center retrospective analysis we identified eight patients after OLT who received treatment with rFVIIa (0.59%). Five out of eight (62.5%) patients suffered graft loss due to hepatic artery thrombosis (HAT). None of these patients had a history of thrombosis or signs of hypercoagulopathy. 60% of the patients who developed HAT had a primary graft non-function. Interestingly, rFVIIa administration was the only risk factor for HAT and consequently for graft loss in our cohort. Other known risk factors such as cold ischaemic time, number of anastomoses, donor age of > 60 years and CMV status could be excluded. Conclusion: This study shows that rFVIIa treatment is a highly likely risk factor for the development of HAT and consequently graft loss in patients after OLT. Thus, usage of rFVIIa in this patient population should be avoided.

Spontaneous Life Threatening Massive Retroperitoneal and Iliopsoas Hemorrhages in Adult Hemophilia - A Patients with Inhibitor - Case Series

Spontaneous retroperitoneal and iliopsoas muscle hemorrhages are rare bleeding episodes in hemophilia patients. Their diagnosis requires high degree of clinical suspicion because presentation may mimic other abdominal and pelvic disorders. These bleedings in severe hemophilia-A patients with factor VIII inhibitor are associated with high morbidity and mortality as control of hemostasis in these cases is challenging. Herein we report 4 adult patients with known congenital Hemophilia-A and factor VIII inhibitor. One of the patients had gigantic retroperitoneal hemorrhage presented with subsequent increase in abdominal pain. The other three patients had significant iliopsoas hemorrhage presented with groin pain. All the events were spontaneous and nontraumatic. These patients were treated with recombinant activated factor VII (rFVIIa) in a dose of 90 μg/kg. Treatment with rFVIIa has significant favorable outcome and all the patients had dramatic response to the treatment and discharged safely from the hospital after 7-10 days of admission. Patients with iliopsoas hemorrhage showed persistent femoral nerve neuropathy. The rarity and spontaneous bleeding episodes at presentation are crucial points for reporting these cases.

Recombinant factor VIIa analog in the management of hemophilia with inhibitors: results from a multicenter, randomized, controlled trial of vatreptacog alfa

BackgroundVatreptacog alfa, a recombinant factor VIIa (rFVIIa) analog with three amino acid substitutions and 99% identity to native FVIIa, was developed to improve the treatment of hemophilic patients with inhibitors.ObjectivesTo confirm the safety and assess the efficacy of vatreptacog alfa in treating bleeding episodes in hemophilic patients with inhibitors.Patients and methodsIn this international, multicenter, randomized, double-blind, active-controlled, crossover, confirmatory phase III trial (adept™2) in patients with hemophilia A or B and inhibitors, bleeds were randomized 3 : 2 to treatment with vatreptacog alfa (one to three doses at 80 μg kg−1) or rFVIIa (one to three doses at 90 μg kg−1). Treatment failures after three doses of trial product (TP) were managed according to the local standard of care.ResultsIn the 72 patients enrolled, 567 bleeds were treated with TP. Both vatreptacog alfa and rFVIIa gave 93% effective bleeding control at 12 h. Vatreptacog alfa was superior to rFVIIa in secondary efficacy outcomes, including the number of doses used to treat a bleed and sustained bleeding control 24–48 h after the first dose. Eight patients (11%) developed antibodies against vatreptacog alfa, including four with cross-reactivity against rFVIIa and one with an in vitro neutralizing effect to vatreptacog alfa.ConclusionsThis large randomized controlled trial confirmed the well-established efficacy and safety profile of rFVIIa, and showed that vatreptacog alfa had similar or better efficacy than rFVIIa. However, because of the development of anti-drug antibodies, a positive benefit–risk profile is unlikely to be achieved with vatreptacog alfa.

An Immunodeficient Mouse Model With Circulating Human Platelets To Evaluate The Platelet Clearance and Pharmacokinetics Of Platelet-Targeted Coagulation Factor VIIa

Treatment of bleeding episodes in hemophilia patients with inhibitory antibodies to factor VIII or factor IX by recombinant activated factor VII (rFVIIa, NovoSeven) has been sub-optimal partly due to its low affinity to activated platelets and its short half-life in circulation. To develop a rFVIIa variant with enhanced coagulant activity, we have targeted rFVIIa to platelets by monoclonal antibodies that recognize the human platelet receptor αIIbβ3. However, the assessment of pharmacokinetic parameters in mice is limited by the lack of recognition of mouse αIIbβ3 by antibodies to human αIIbβ3. The present study addresses the need to develop appropriate in vivo models to study this new class of bypass therapeutics.First, we evaluated the survival of human platelets in hemophilia A, NOD/SCID, and NOD/SCID/gamma (NSG) mice. Platelet concentrates were prepared from normal human donors and transfused retro-orbitally into mice. The whole blood from dosed mice was then collected via tail vein laceration at various times and the human platelet counts in blood was determined by flow cytometry after staining with fluorescently labeled antibodies against human CD42b, mouse CD61, human FVII to visualize the human platelets, mouse platelets, and the FVIIa candidate that bound to human platelets, respectively. The half-life of human platelets in NOD/scid/gamma (NSG) mice was approximately 4 hours, which is considerably longer than the 0.8 hour half-life observed in hemophilia A mice.The effect of platelet-targeted FVIIa variants on the clearance of human platelets was then investigated in NSG mice. The FVIIa candidates were pre-selected for their inactivity toward human platelet activation and aggregation, as determined in a battery of in vitro assays. In agreement with the in vitro results, all of these selected candidates did not affect the clearance of the transfused human platelets when dosed in NSG mice at 5 nmol/kg. In contrast, a control antibody fusion protein that is known to activate platelets and cause thrombocytopenia in vivo led to rapid platelet clearance in NSG mice. Similar results were observed for these proteins in cynomolgous monkeys when dosed at 2 nmol/kg.The NSG mice with circulating human platelets were also explored to evaluate the clearance of FVIIa candidates that remain platelet-associated in vivo. To improve the pharmacokinetics, we have fused XTEN, a hydrophilic peptide that increases the dynamic radius of payload proteins, to the platelet-targeted FVIIa candidates. When tested in NSG mice model for the clearance of platelet-associated protein, addition of XTEN markedly reduced the clearance rate, resulting in several fold increase in exposure.Together these data indicate that NSG mice with circulating human platelets can be used to assess the safety and pharmacokinetics of the platelet-targeted FVIIa variants, and the method can be adapted to evaluate other agents designed to utilize platelet-targeting approaches. Disclosures:Tan:Biogen Idec: Employment, Equity Ownership. Chen:Biogen Idec: Employment, Equity Ownership. Salas:Biogen Idec: Employment, Equity Ownership. Peters:Biogen Idec: Employment, Equity Ownership. Light:Biogen Idec: Employment; Biogen Idec: Equity Ownership. Jiang:Biogen Idec: Employment; Biogen Idec: Equity Ownership.

Development of a Transgenic Mouse Model with Immune Tolerance for Human Coagulation Factor VIIa

Human factor VIIa (FVIIa) is commonly used as bypassing therapy to treat bleeding episodes in hemophilia patients with neutralizing antibodies to factors VIII (FVIII) or IX (FIX). There is a need for a suitable animal model to assess the immunogenicity of new FVIIa products during preclinical development. The aim of this study was the design of a novel transgenic mouse model with immune tolerance to human FVIIa. The model was generated by transgenic expression of human F7 cDNA. FVIIa-specific immune responses after treatment with human FVIIa were assessed by analyzing circulating antibodies, antibody producing plasma cells and CD4(+) T cells. In contrast to wild-type mice, human FVII transgenic mice did not develop antibodies when treated with human FVIIa. The immune tolerance was specific and could be broken by application of human FVIIa together with a strong stimulus of the innate immune system. Break of tolerance was associated with increased numbers of pro-inflammatory FVIIa-specific CD4(+) T cells. The new mouse model is suitable to study the influence of the innate immune system on maintenance and break of immune tolerance against FVIIa and could be used to assess the immunogenicity of new FVIIa products during pre-clinical development.

Safety of Recombinant Activated Factor VII (rFVIIa) in Patients with Congenital Hemophilia with Inhibitors: Overall Dose Exposure and Intervals Following >240 Mcg/Kg Doses Across Trial, Registry and Diary Studies,

Abstract 3316▪▪This icon denotes a clinically relevant abstract Objective:Recombinant FVIIa (rFVIIa) is indicated for the treatment of bleeding episodes in hemophilia patients with inhibitors at a dose of 90 mcg/kg every 2–3 hours, or as a single 270 mcg/kg rFVIIa dose (outside US). As patient response and bleeds are variable, treatment is often individualized by the center and by the patient/caregiver administering rFVIIa. With home treatment, it is difficult to ascertain how often patients use higher doses (>90 mcg/kg), and whether these doses are associated with increased risk of thromboembolic events (TEs). The aim of this analysis was to understand the safety of higher rFVIIa doses and the intervals to subsequent doses. Methods:Data for rFVIIa on-demand (OD) bleed treatment in inhibitor patients were obtained from 6 sources: 2 prospective randomized studies; 1 prospective observational US diary study (DOSE); the US-based Hemostasis and Thrombosis Research Society (HTRS) Registry; the international ONE Registry; and the HemoRec registry (Czech data only). Data on prophylactic (PPX) rFVIIa use was obtained from 3 sources: 1 prospective randomized trial; 1 retrospective chart review study (PRO-PACT); and the HemoRec registry (Czech data). Data on intervals between high initial/subsequent doses and any further bypassing agent dose in OD treatment were analyzed from 3 sources that reported time of administration (DOSE, ONE and HemoRec). All studies had data safety monitoring in the form of explicit surveillance, positive affirmations of lack of adverse events, or chart reviews. Overlap in patient participation in studies could not be ruled out; however, all data are believed to be non-overlapping due to study timelines. Demographics, rFVIIa dosing, and frequency of TEs were analyzed and reported using descriptive statistics. Results:A total of 481 inhibitor patients reported using 61,734 rFVIIa doses either for OD treatment or PPX. Most patients had hemophilia A (87%) and were Caucasian (79%). Age ranged from <1 to 64 years (40% >18y). All data sources included the use of rFVIIa doses higher than current US-recommendations. Overall, 52.2% of doses (45.9% in adults) were >120 mcg/kg, the highest dose referenced from previous clinical trials in the US package insert.All PatientsAdults (Age >18)# Patients481192# Bleeds3,9471,706# Prophylaxis Days43,1357,282# rFVIIa Doses (#, %)>240 mcg/kg9,27415.0%1,37112.4%>160 to 240 mcg/kg13,72322.2%2,05918.7%>120 to 160 mcg/kg9,24715.0%1,62514.7%80–120 mcg/kg25,53741.4%5,38048.8%<80 mcg/kg3,9536.4%5865.3%Total61,734100.0%11,021100.0%For the152 patients from DOSE, ONE and HemoRec included in the dosing interval analyses, age ranged from <1 to 64 y (45% >18y). Patients received 3,042 rFVIIa doses for 1,017 bleeds. These included 361 initial rFVIIa doses (36%) >240 mcg/kg, including 136 followed by a second dose of bypassing agent (130 with rFVIIa; 15 with pd-aPCC). There were 670 doses >240 mcg/kg used throughout treatments (22%), including 327 followed by a subsequent dose (311 with rFVIIa; 23 with pd-aPCC). Most subsequent doses (79%) occurred after >8 hrs.After Initial Dose >240 mcg/kgAfter Any Dose >240 mcg/kgn%n%Doses >240 mcg/kg136327Interval to next dose<3 hrs118.1%298.9%3 up to 4 hrs1410.3%185.5%4 up to 6 hrs32.2%61.8%6 up to 8 hrs64.4%175.2%8 up to 12 hrs1410.3%247.3%12 up to 18 hrs2518.4%4513.8%18 up to 24 hrs96.6%144.3%24 hrs or greater5439.7%17453.2%No TEs were reported across the 8 sources. Conclusions:A review of 61,734 cumulative rFVIIa doses in studies with explicit safety monitoring demonstrates the use and safety of rFVIIa doses >90 mcg/kg in inhibitor patients. When doses >240 mcg/kg were followed by other bypassing agent doses, the dosing interval was >8 hrs after 79% of doses and >24 hrs after 53% of doses. Unlike MedWatch and passive surveillance where underreporting is common, we expect that the explicit surveillance in these studies would adequately identify TE events. Thus, the lack of TEs supports the overall low TE occurrence (0.28%) reported in the original registration trials in inhibitor patients using ≤90 mcg/kg. These data reinforce that the arterial thrombosis risk identified in meta-analyses outside of licensed indications (critical bleeds) are unique to those populations and do not apply to inhibitor patients. Furthermore, higher doses may provide an opportunity to improve bleed treatment with less frequent injections and decreased follow-up infusions. Disclosures:Shapiro:Novo Nordisk inc.: Consultancy, Research Funding, Speakers Bureau. Off Label Use: rFVIIa use in indicated population of congential hemophilia with inhibitors at doses that differ from those in the prescribing information. Neufeld:Novo Nordisk Inc.: Consultancy, Research Funding. Blanchette:Novo Nordisk: Consultancy. Chambost:Novo Nordisk: Consultancy. Salaj:Novo Nordisk: Consultancy. Gut:Novo Nordisk Inc.: Employment. Cooper:Novo Nordisk Inc.: Employment.

Endothelial Cell Protein C Receptor-Mediated Redistribution and Tissue-Level Accumulation of Pharmacologically Administered Recombinant Human Factor VIIa

Abstract 532Recombinant factor VIIa (FVIIa) has been demonstrated to be an effective hemostatic agent for treatment of severe hemophilia patients. Recent clinical studies suggest that the prophylactic use of FVIIa markedly reduces the number of bleeding episodes in hemophilic patients with inhibitors. Clinical evidence from hemophilic patients during prophylaxis and post-prophylaxis suggest that the hemostatic effect of FVIIa surpassed the short circulatory half-life of FVIIa. At present, mechanisms by which this phenomenon occurs are not precisely known. Our laboratory has formerly established that FVIIa is capable of binding to the endothelial protein C receptor (EPCR) on endothelial cells, yet the significance of this interaction in hemostasis, and especially in prophylaxis, is not fully understood. Recent studies from our laboratory using a murine model have demonstrated that pharmacologically administered FVIIa rapidly associates with the endothelium, enters into extravasculature where it can interact with TF, and remains functionally active in tissues for an extended period of time. The aim of the present study was to determine if interaction of FVIIa with EPCR on the endothelium and subsequent EPCR-dependent transcytosis serves as a mechanism by which pharmacologically administered FVIIa is transported to tissues and retained for greater periods of time compared to its circulatory half-life. We have employed transgenic murine lines, including EPCR-over expressing, EPCR-deficient, and wild-type (WT) mice, to investigate the function of EPCR in the biodistribution of FVIIa and its extended stay in tissues. Mice were injected with human FVIIa (120 μg/kg b.w.) via tail vein and at 30 min, 3 h, 8 h, and 24 h following FVIIa administration, blood was collected via cardiac puncture and various tissues were harvested for antigen and immunohistochemical analyses. Our studies reveal that, following intravenous injection, FVIIa rapidly disappears from plasma (plasma levels of FVIIa in WT mice at 30 min and 3 h post-injection were ∼ 15% and <1%, respectively, of that which was injected) and associates with the endothelium in an EPCR-dependent manner. At 30 min post-injection, plasma levels of FVIIa were significantly higher in EPCR-deficient mice as compared to WT mice whereas plasma FVIIa levels were significantly lower in EPCR-over expressing mice compared to WT mice, suggesting that EPCR facilitates the sequestration of FVIIa from the bloodstream. This EPCR-dependent decrease in plasma FVIIa coincides with an EPCR-dependent increase in antigen levels of FVIIa in tissue homogenates. FVIIa antigen in the lungs of EPCR-over expressing mice at 30 min following FVIIa administration was approximately 6-fold higher than that which was found in WT mice. At the corresponding time, FVIIa antigen in EPCR-deficient mice was approximately 35% lower than that which was measured in WT mice. FVIIa antigen in the lung tissue of EPCR-over expressing mice remained relatively stable or slightly increased at 3, 8 and 24 h post FVIIa administration. FVIIa levels in tissue homogenates of WT and EPCR-deficient mice remained significantly lower compared to EPCR-over expressing mice at all time points. Immunohistochemical analysis of lung, skin, and bone-joint sections revealed that association of FVIIa with the endothelium is more pronounced in EPCR-over expressing mice as compared to lesser, albeit appreciable, levels in WT mice; EPCR-deficient mice showed negligible association of FVIIa with the endothelium. Association of FVIIa with the endothelium in EPCR-over expressing mice was maximal at 30 min and was thereafter progressively reduced at each time point; FVIIa association with the endothelium was undetectable at 24 h post FVIIa administration. The observation that EPCR-dependent association of FVIIa with the endothelium is most pronounced soon after injection and subsequently declines time-wise, combined with the retention of FVIIa in tissue homogenates for extended periods, implies that FVIIa bound to the endothelium enters tissues in an EPCR-dependent manner. These findings put forward an EPCR-dependent mechanism by which pharmacologically administered FVIIa can relocate to and be retained within tissues where TF resides, which conceivably may prime coagulation thereby contributing to hemostasis. Disclosures:Hedner:Novo Nordisk: Consultancy. Rao:Novo Nordisk: Research Funding.

Economical comparison of APCC vs. rFVIIa for mild‐to‐moderate bleeding episodes in haemophilia patients with inhibitors

To construct a cost-minimization model comparing activated prothrombin complex concentrates (APCC) vs. recombinant factor VIIa (rFVIIa) in haemophilia patients with inhibitors from a US third party payer perspective. A literature-based decision model was used to model inhibitor treatment costs and outcomes. As existing clinical trials fail to demonstrate differences in the relative efficacy or safety of APCC vs. rFVIIa, we assumed the same efficacy for both products in the base-case. Regimens of APCC (75 IU kg⁻¹ × 2 doses) and rFVIIa (90 μg kg⁻¹× 3 doses) were assumed according to manufacturer recommendations. If the first-line treatment failed, patients chose to continue the current treatment or switch to another drug. All costs were adjusted to 2009 US dollars. Sensitivity analyses on the infusion frequency, efficacy, unit price, switch rate, re-bleed rate and body weight were performed to assess model robustness. In the base-case, the total medical cost to treat a bleed with APCC or rFVIIa as first-line medication was US$25,969 and US$35,838, respectively. One-way sensitivity analyses showed that results were insensitive to the efficacy of rFVIIa, unit price of APCC or rFVIIa, switch rate, re-bleed rate or body weight. The rFVIIa will reach cost neutrality when the efficacy of APCC is as low as 60%, or rFVIIa is infused only twice for each line, or APCC is infused three times for each line. Two-way sensitivity analyses showed that results were quite sensitive to the assumed infusion frequency for both products. First-line APCC compared with rFVIIa can be a cost-saving alternative for home treatment of mild-to-moderate bleeds in haemophilia patients with inhibitors.

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 (5-40 K 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-5 K PEG, rFVIIa-10 K PEG, rFVIIa-20 K PEG and rFVIIa-40 K 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-10 K PEG and rFVIIa-40 K PEG of approximately 7 and 12 h, respectively. The rFVIIa-10 K PEG and rFVIIa-40 K 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.

Experience with a single dose of recombinant activated factor VII for the management of mild-to-moderate bleeds in haemophilia

Experience with a single dose of recombinant activated factor VII for the management of mild-to-moderate bleeds in haemophilia

Phase I, Randomized, Double-Blind, Placebo-Controlled, Single-Dose Escalation Study of the rFVIIa Variant (BAY 86–6150) In Hemophilia A or B with or without Inhibitors.

AbstractAbstract 3679Bleeding episodes in hemophilia A or B patients with inhibitors to factors VIII or IX are commonly managed with bypassing agents such as recombinant factor VIIa (rFVIIa). However, currently available rFVIIa treatment is associated with variable response rates and a short elimination half-life, often necessitating the administration of multiple doses to control bleeding. BAY 86–6150, a human rFVIIa variant, was developed to provide a longer-acting and more potent activated factor VII in the management of bleeding episodes in patients with hemophilia who developed inhibitors.The safety, tolerability, pharmacodynamic/pharmacokinetic (PD/PK) profiles, and immunogenicity of BAY 86–6150 in nonbleeding patients with hemophilia was investigated in a phase I, randomized, double-blind, placebo-controlled, single-dose escalation study. The patient population comprised nonbleeding men aged 18–65 years with moderate or severe hemophilia A or B with or without inhibitors. 16 patients were randomized 3:1 to escalating doses of BAY 86–6150 at 6.5, 20, 50, or 90 μg/kg (n=3 each) or placebo (n=4). Patients were followed for 50 days postdose. The objective of the trial was to evaluate the safety and tolerability of BAY 86–6150, with adverse events (AEs) as the primary endpoint. Other endpoints included PK parameters, the effects of BAY 86–6150 on hemostasis markers and coagulation, and the immunogenicity of the compound. BAY 86–6150 was not associated with clinically significant AEs or dose-limiting toxicities and the PK parameters were linear over the dose range, with a half-life of 5–7 hours. Patients demonstrated consistent, dose-dependent thrombin generation ex-vivo in platelet-poor plasma (mean peak effect 26–237 nM thrombin from 6.5–90 μg/kg). Peak thrombin levels over time paralleled the presence of BAY 86–6150 by PK analysis, indicating that the drug in circulation retained activity. There were corresponding decreases in time and duration in the activated partial thromboplastin and prothrombin time testing. In contrast, there was no dose response seen in the thrombogenicity markers evaluated including antithrombin III, prothrombin fragment 1+2, TAT, and D-dimer.One patient demonstrated antibody activity to both BAY 86–6150 and to rVIIa as determined by ELISA testing at baseline. The level of inhibition and titer remained constant when evaluated in follow-up on day 29 and day 49.The data safety monitoring board recommended progression to the highest proposed dose (90 μg/kg). The phase II/III studies are designed to evaluate the clinical efficacy and safety as well as corresponding laboratory markers. Results of the present study suggest that the novel rFVIIa agent BAY 86–6150 is safe and has increased potency and a longer half-life compared with the currently available rFVIIa therapy. BAY 86–6150 may therefore have the potential to improve the treatment of bleeding episodes in hemophilic patients with inhibitors. Disclosures:Mahlangu:Bayer Helathcare: Consultancy, Honoraria, Speakers Bureau; NovoNordisk: Consultancy, Honoraria, Speakers Bureau; IAVI: Consultancy; Maxygen: Consultancy. Coetzee:Bayer Schering Pharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Laffan:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Baxter: Honoraria, Membership on an entity's Board of Directors or advisory committees; NovoNordisk: Membership on an entity's Board of Directors or advisory committees. Windyga:Bayer HealthCare Pharmaceuticals: Research Funding; Bayer, Baxter, Behring, NovoNordisk, Octapharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Yee:Bayer HealthCare Pharmaceuticals: Research Funding. Schroeder:Bayer Schering Pharma AG: Employment, Equity Ownership. Haaning:Bayer HealthCare Pharmaceuticals: Employment, Equity Ownership. Siegel:Bayer HealthCare Pharmaceuticals: Employment, Equity Ownership. Lemm:Bayer Schering Pharma AG: Employment, Equity Ownership.

Safety, pharmacokinetics and efficacy of factor VIIa formulated with PEGylated liposomes in haemophilia A patients with inhibitors to factor VIII – an open label, exploratory, cross‐over, phase I/II study

Recombinant activated factor VIIa (FVIIa) is a bypassing agent used to treat bleeding episodes in haemophilia patients with inhibitors to factor VIII (FVIII) and factor IX. The pharmacological effect of FVIIa is short-lived and therefore with the recommended dose of 90 μg kg(-1), a bleeding episode is treated with multiple injections. A long-acting form of FVIIa that can ensure adequate haemostasis with a single infusion, without increasing the thrombotic risk, would therefore be beneficial. PEGylated liposomes (PEGLip) have been shown to bind FVIIa and to improve haemostatic efficacy in preclinical experiments. In the present phase I/II clinical trial, we assessed the safety and efficacy of PEGLip-formulated FVIIa in severe haemophilia A patients (FVIII≤1%) with inhibitors to FVIII. Each patient received one prophylactic infusion of standard FVIIa and one prophylactic infusion of PEGLip-formulated FVIIa. The order of the infusions was randomized and the two infusions were separated by a ten-day washout period. Efficacy assessed by thromboelastography revealed that PEGLip-FVIIa induced significantly shorter clotting times and produced higher clot firmnesses than standard FVIIa. Thrombin generation assays showed that PEGLip-FVIIa induced faster thrombin generation and higher peak levels of thrombin than standard FVIIa. These effects lasted up to 5 h postinfusion. Measurements of D-dimer, prothrombin fragment 1+2 and fibrinogen showed no significant differences between the PEGLip-FVIIa and standard FVIIa treatments. PEGLip-FVIIa therefore showed improved haemostatic efficacy without increased risk of thrombosis and may be further developed for the treatment for bleeding episodes in haemophilia patients with inhibitors.

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.