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Background: Hereditary angioedema (HAE) due to C1-inhibitor (C1-INH) deficiency is a rare genetic disorder characterized by disabling episodes of edema that commonly affect the skin as well as the gastrointestinal tract and upper airway. Prophylactic therapy can decrease the severity and number of attacks. Long-term symptom control and rescue medication use were evaluated in patients with HAE who received subcutaneous (SC) C1-INH enrolled in an open-label extension (OLE) of the phase III COMPACT (Clinical Studies for Optimal Management of Preventing Angioedema with Low-Volume Subcutaneous C1-Inhibitor Replacement Therapy) trial, including a subgroup analysis of patients treated for ≥12 months. Methods: The OLE study evaluated patients ≥ 6 years old who had had four or more attacks over 2 consecutive months before enrollment. Patients naive for C1-INH (SC) and patients in the COMPACT rollover trial were included. The patients were randomized to receive C1-INH (SC) 40 or 60 IU/kg twice weekly for 52 weeks. U.S. patients were eligible to continue for up to 140 weeks. Results: A total of 63 patients were randomized to the U.S. Food and Drug Administration approved dose of 60 IU/kg; 24 subjects were treated for at least 12 months. For the 63 subjects, the median (range) attacks per month were 0.09 (0.0‐4.0) and per year were 1.0 (0.0‐48.0). Two-thirds of the patients used rescue medication fewer than once per year. For the 24 patients with ≥ 12 months of exposure, the median (range) attacks per month and per year were 0.017 (0.000-2.4) and 0.199 (0.000-28.94), respectively. Of these patients, 12 (50%) were attack free throughout the duration of the study, and 3 (12.5%) had fewer than one attack per year. Conclusion: Prophylaxis with C1-INH (SC) provided sustained reductions in attack frequency and decreased rescue medication use, with a substantial proportion of patients being attack free.

Background: Hereditary angioedema (HAE) due to C1 inhibitor (C1INH) deficiency is characterized by recurrent attacks of edema of the skin and mucosal tissues. Symptoms usually present during childhood (mean age at first attack, 10 years). Earlier symptom onset may predict a more severe disease course. Subcutaneous (SC) C1INH is indicated for routine prophylaxis to prevent HAE attacks in adolescents and adults. We analyzed the long-term efficacy of C1INH (SC) in subjects ≤17 years old treated in an open-label extension (OLE) of the pivotal phase III Clinical Study for Optimal Management of Preventing Angioedema with Low-Volume Subcutaneous C1 Inhibitor Replacement Therapy (COMPACT) trial. Methods: Eligible subjects (age ≥6 years, with ≥4 attacks over 2 consecutive months before entry into the OLE or placebo-controlled COMPACT trial) were treated with C1INH (SC) 40 or 60 IU/kg twice weekly for 52-140 weeks. Subgroup analyses by age (≤17 vs. >17 years) were performed for key efficacy endpoints. Results: Ten subjects were ≤17 years old [mean (range) age, 13.3 (8-16) years, 3 subjects

Objectives Acquired coagulopathy may be associated with bleeding risk. Approaches to restore haemostasis include administration of coagulation factor concentrates, but there are concerns regarding potential prothrombotic risk. The present study assessed the prothrombotic potential of four-factor prothrombin complex concentrate (4F-PCC) versus activated PCC (aPCC) and recombinant factor VIIa (rFVIIa), using three preclinical animal models. Methods The first model was a modified Wessler model of venous stasis-induced thrombosis in rabbit, focusing on dilutional coagulopathy; the second model employed the same system but focused on direct oral anticoagulant reversal (i.e. edoxaban). The third model assessed the prothrombotic impact of 4F-PCC, aPCC and rFVIIa in a rat model of ferric chloride-induced arterial thrombosis. Results In the first model, thrombi were observed at aPCC doses ≥10 IU/kg (therapeutic dose 100 IU/kg) and rFVIIa doses ≥50 μg/kg (therapeutic dose 90 μg/kg), but not 4F-PCC 50 IU/kg (therapeutic dose 50 IU/kg). The impact of 4F-PCC (up to 300 IU/kg) on thrombus formation was evident from 10 minutes post-administration, but not at 24 hours post-administration; this did not change with addition of tranexamic acid and/or fibrinogen concentrate. 4F-PCC-induced thrombus formation was lower after haemodilution versus non-haemodilution. In the second model, no prothrombotic effect was confirmed at 4F-PCC 50 IU/kg. The third model showed lower incidence of thrombus formation for 4F-PCC 50 IU/kg versus aPCC (50 U/kg) and rFVIIa (90 μg/kg). Conclusions These results suggest that 4F-PCC has a low thrombotic potential versus aPCC or rFVIIa, supporting the clinical use of 4F-PCC for the treatment of coagulopathy-mediated bleeding.

Subcutaneous C1-inhibitor (HAEGARDA, CSL Behring), is a US Food and Drug Administration (FDA)-approved, highly concentrated formulation of a plasma-derived C1-esterase inhibitor (C1-INH), which, in the phase III Clinical Studies for Optimal Management in Preventing Angioedema with Low-Volume Subcutaneous C1-inhibitor Replacement Therapy (COMPACT) trial, reduced the incidence of hereditary angioedema (HAE) attacks when given prophylactically. Data from the COMPACT trial were used to develop a repeated time-to-event model to characterize the timing and frequency of HAE attacks as a function of C1-INH activity, and then develop an exposure-response model to assess the relationship between C1-INH functional activity levels (C1-INH(f)) and the risk of an attack. The C1-INH(f) values of 33.1%, 40.3%, and 63.1% were predicted to correspond with 50%, 70%, and 90% reductions in the HAE attack risk, respectively, relative to no therapy. Based on trough C1-INH(f) values for the 40 IU/kg (40.2%) and 60 IU/kg (48.0%) C1-INH (SC) doses, the model predicted that 50% and 67% of the population, respectively, would see at least a 70% decrease in the risk of an attack.

Background For the prevention of attacks of hereditary angioedema (HAE), the efficacy and safety of subcutaneous human C1-esterase inhibitor (C1-INH[SC]; HAEGARDA, CSL Behring) was established in the 16-week Clinical Study for Optimal Management of Preventing Angioedema with Low-Volume Subcutaneous C1-Inhibitor Replacement Therapy (COMPACT). Objective To assess the long-term safety, occurrence of angioedema attacks, and use of rescue medication with C1-INH(SC). Methods Open-label, randomized, parallel-arm extension of COMPACT across 11 countries. Patients with frequent angioedema attacks, either study treatment-naive or who had completed COMPACT, were randomly assigned (1:1) to 40 IU/kg or 60 IU/kg C1-INH(SC) twice per week, with conditional uptitration to optimize prophylaxis (ClinicalTrials.gov registration no. NCT02316353). Results A total of 126 patients with a monthly attack rate of 4.3 in 3 months before entry in COMPACT were enrolled and treated for a mean of 1.5 years; 44 patients (34.9%) had more than 2 years of exposure. Mean steady-state C1-INH functional activity increased to 66.6% with 60 IU/kg. Incidence of adverse events was low and similar in both dose groups (11.3 and 8.5 events per patient-year for 40 IU/kg and 60 IU/kg, respectively). For 40 IU/kg and 60 IU/kg, median annualized attack rates were 1.3 and 1.0, respectively, and median rescue medication use was 0.2 and 0.0 times per year, respectively. Of 23 patients receiving 60 IU/kg for more than 2 years, 19 (83%) were attack-free during months 25 to 30 of treatment. Conclusions In patients with frequent HAE attacks, long-term replacement therapy with C1-INH(SC) is safe and exhibits a substantial and sustained prophylactic effect, with the vast majority of patients becoming free from debilitating disease symptoms.

Background Patients aged 65 years and older with hereditary angioedema (HAE) owing to C1-inhibitor (C1-INH) deficiency may have an altered response to treatment and are at higher risk for treatment-related adverse events (AEs) because of comorbidities and polypharmacy. Objective To investigate the safety and efficacy of subcutaneous C1 esterase inhibitor (C1-INH) in patients aged 65 years and older treated in an open-label extension of a phase 3 trial. Methods Eligible patients (≥4 attacks for more than 2 consecutive months) were randomized to receive twice-weekly subcutaneous C1-INH with a dosage of 40 IU/kg or 60 IU/kg for 52 to 140 weeks. Safety end points and efficacy outcomes were evaluated for patients aged 65 years and above and younger than 65 years. Results Of the 126 patients treated, 10 were 65 years and older (mean age [range], 68 [65-72 years]). A total of 8 of 10 patients had multiple comorbidities, and 6 of these 10 patients were taking more than 5 non–HAE-related drugs concomitantly. AEs occurring in more than 1 patient included injection site bruising (n = 2, related), injection site pain (n = 2, related), urinary tract infection (n = 2, unrelated), and diarrhea (n = 2, unrelated). No thromboembolic events or cases of anaphylaxis were reported. Two patients aged 65 years and older experienced unrelated serious AEs (dehydration and hypokalemia in 1 and pneumonia and an HAE attack leading to hospitalization in another). A total of 6 of 9 evaluable patients were responders, with a greater than or equal to 50% reduction in HAE attacks vs prestudy; 6 of 10 patients had less than 1 attack over 4 weeks and 3 were attack-free (median attack rate, 0.52 attacks per month). Conclusion Subcutaneous C1-INH was well-tolerated and effective in the management of HAE in patients aged 65 years and older with multiple comorbid conditions and polypharmacy.

Human apolipoprotein A-I preparations reconstituted with phospholipids (reconstituted high-density lipoprotein [HDL]) have been used in a large number of animal and human studies to investigate the physiological role of apolipoprotein A-I. Several of these studies observed that intravenous infusion of reconstituted HDL might cause transient elevations in plasma levels of hepatic enzymes. Here we describe the mechanism of this enzyme release. Observations from several animal models and in vitro studies suggest that the extent of hepatic transaminase release (alanine aminotransferase [ALT]) correlates with the movement of hepatic cholesterol into the blood after infusion. Both the amount of ALT release and cholesterol movement were dependent on the amount and type of phospholipid present in the reconstituted HDL. As cholesterol is known to dissolve readily in phospholipid, an HDL preparation was loaded with cholesterol before infusion into rats to assess the role of diffusion of cholesterol out of the liver and into the reconstituted HDL. Cholesterol-loaded HDL failed to withdraw cholesterol from tissues and subsequently failed to cause ALT release. To investigate further the role of cholesterol diffusion, we employed mice deficient in SR-BI, a transporter that facilitates spontaneous movement of cholesterol between cell membranes and HDL. These mice showed substantially lower movement of cholesterol into the blood and markedly lower ALT release. We conclude that initial depletion of hepatic cholesterol initiates transient ALT release in response to infusion of reconstituted HDL. This effect may be controlled by appropriate choice of the type and amount of phospholipid in reconstituted HDL. Copyright © 2015 John Wiley & Sons, Ltd.

Summary Background Recombinant factor VIIa (rFVIIa) is approved for use in controlling bleeding episodes in people with hemophilia who have developed inhibitors to replacement therapy. Due to its short half-life (t½), frequent injections are required, limiting its use as a prophylactic treatment. A novel, recombinant fusion protein linking coagulation factor VIIa with albumin (rVIIa-FP) has been developed to extend the t½ of rFVIIa. Objectives The aim of our studies was to investigate the pharmacokinetic/pharmacodynamic characteristics of rVIIa-FP in preclinical animal species. Methods Pharmacokinetic (PK) parameters were derived after single intravenous dosing in hemophilia A mice, rats, rabbits and monkeys. PK analysis was based on human FVII plasma levels determined by measuring FVII antigen levels by ELISA in mice and rats, and FVIIa activity using STACLOT® VIIa-rTF in rabbits and monkeys. Induction of thrombin generation was investigated in mice, while hemostatic activity was assessed by thrombus formation in rabbits. Results Compared with rFVIIa, rVIIa-FP displayed a prolonged t½, enhanced in vivo recovery and reduced clearance in all species investigated. In mice, 16 h after treatment with rVIIa-FP, thrombin levels were quantifiable, indicating prolonged efficacy, whereas values had approached baseline at this time after treatment with rFVIIa. After 12 h, hemostatic efficacy was negligible in rFVIIa-treated rabbits, but sustained in animals receiving rVIIa-FP. Conclusions These studies indicate that the longer t½ of rVIIa-FP compared with rFVIIa translates into extended activity. These findings suggest that rVIIa-FP has the potential to be administered less frequently than rFVIIa-containing concentrates in clinical use.

Introduction Replacement therapy with subcutaneous C1-esterase inhibitor (C1-INH[SC]) 60 IU/kg twice weekly is approved for routine prophylaxis to prevent hereditary angioedema (HAE) attacks. Coagulation and fibrinolytic parameters levels tend to be elevated in HAE patients. We evaluated the effects of C1-INH(SC) on these parameters. Methods In the COMPACT study, subjects received 40 IU/kg or 60 IU/kg of plasma-derived C1-INH(SC) and a corresponding placebo, as prophylaxis over 16 weeks each. In the open-label extension (OLE), subjects received 40 IU/kg or 60 IU/kg of C1-INH(SC) for up to 140 weeks. Exploratory analyses included the assessment of coagulation and fibrinolytic parameters (D-dimer, Prothrombin Fragments [PF] 1+2, activated Partial Thromboplastin Time [aPTT], Fibrinogen, and Prothrombin International Normalized Ratio [PT-INR]) at prescheduled visits. Results Coagulation and fibrinolytic parameters were reported above the normal range at baseline. Treatment with C1-INH(SC) 60 IU/kg resulted in median decrease from baseline for D-dimer (COMPACT [baseline to Week 14]: 605.0 to 330.0 ng/mL; OLE [baseline to Week 140]: 510.0 to 330.0 ng/mL) and PF 1+2 (COMPACT [baseline to Week 14]: 264.0 to 185.0 pmol/L; OLE [baseline to Week 140]: 218.5 to 159.0 pmol/L). The aPTT, Fibrinogen, and PT-INR levels were stable relative to baseline over the treatment period. Results refer only to the Food and Drug Administration (FDA) approved 60 IU/kg dose. Conclusions A reduction or stabilization in coagulation and fibrinolytic parameters was observed in HAE patients treated prophylactically with C1-INH(SC). No related thromboembolic events were reported during treatment with C1-INH (SC).

Background and purpose Ischemic stroke provokes severe brain damage and remains a predominant disease in industrialized countries. The coagulation factor XII (FXII)-driven contact activation system plays a central, but not yet fully defined pathogenic role in stroke development. Here, we investigated the efficacy of the FXIIa inhibitor rHA-Infestin-4 in a rat model of ischemic stroke using both a prophylactic and a therapeutic approach. Methods For prophylactic treatment, animals were treated intravenously with 100 mg/kg rHA-Infestin-4 or an equal volume of saline 15 min prior to transient middle cerebral artery occlusion (tMCAO) of 90 min. For therapeutic treatment, 100 mg/kg rHA-Infestin-4, or an equal volume of saline, was administered directly after the start of reperfusion. At 24 h after tMCAO, rats were tested for neurological deficits and blood was drawn for coagulation assays. Finally, brains were removed and analyzed for infarct area and edema formation. Results Within prophylactic rHA-Infestin-4 treatment, infarct areas and brain edema formation were reduced accompanied by better neurological scores and survival compared to controls. Following therapeutic treatment, neurological outcome and survival were still improved although overall effects were less pronounced compared to prophylaxis. Conclusions With regard to the central role of the FXII-driven contact activation system in ischemic stroke, inhibition of FXIIa may represent a new and promising treatment approach to prevent cerebral ischemia/reperfusion injury.

Summary. Background: One limitation of the direct thrombin inhibitor dabigatran is the lack of specific antidotes that allow acute bleeding events to be managed or urgent interventional procedures performed. Prothrombin complex concentrates (PCCs) have served as a standard treatment for the reversal of coumarin anticoagulation. Objectives: This study was designed to determine in an animal model whether a PCC (Beriplex P/N) can effectively reverse the effects of dabigatran. An additional objective was to evaluate markers of dabigatran-associated bleeding diathesis. Methods: Anesthetized rabbits were treated with 0.4 mg kg−1 dabigatran followed by PCC doses of 20, 35 or 50 IU kg−1 or placebo. After a standardized kidney incision, volume of blood loss and time to hemostasis were determined. Results: From an initial mean of 29 mL, blood loss progressively declined by 5.44 mL with a 95% confidence interval (CI) of 2.21–8.67 mL per 10 IU kg−1 increment in PCC dose (P = 0.002). At a PCC dose of 50 IU kg−1 blood loss was fully normalized. Increasing PCC doses shortened the median time to hemostasis from 20.0 to 5.7 min (P

Objective To evaluate the cardiorespiratory effects and plasma concentrations of medetomidine-midazolam-ketamine (MMK) combinations administered by intramuscular (IM) or subcutaneous (SC) injection in sable ferrets (Mustela putorius furo). Study design Prospective randomized experimental study. Animals Eighteen adult ferrets: weight median 1.19 (range 0.81–1.60) kg. Methods Animals were allocated to one of three groups: group IM07 received 20 μg kg−1 medetomidine, 0.5 mg kg−1 midazolam and 7 mg kg−1 ketamine IM; group IM10 20 μg kg−1 medetomidine, 0.5 mg kg−1 midazolam and 10 mg kg−1 ketamine IM; and group SC10 20 μg kg−1 medetomidine, 0.5 mg kg−1 midazolam and 10 mg kg−1 ketamine SC. Following instrumentation, cardiorespiratory parameters and plasma drug concentrations were measured every 5 minutes (T5–T30) for 30 minutes Ferrets were then euthanased. Data were analysed using anova for repeated measures. p Results Results are mean ± SD. Induction of anaesthesia (minutes) in IM07 and IM10 [2 (1)] was significantly faster than in SC10 [5 (2)]. All groups demonstrated the following: results given as groups IM07, IM10 and SC10 respectively. Mean arterial blood pressures (mmHg) were initially high [186 (13); 174 (33) and 174 (9) at T5] but decreased steadily. Pulse rates were initially 202 (20), 213 (17) and 207 (33) beats minute−1, decreasing with time. PaO2 (mmHg) was low [54.0 (8), 47.7 (10) and 38.5 (1)] at T5, although in groups IM07 and IM10 it increased over time. Plasma concentrations of all drugs were highest at T5 (36, 794 and 8264 nmol L−1 for medetomidine, midazolam and ketamine, respectively) and decreased thereafter: for both midazolam and ketamine, concentrations in IM07 and IM10 were higher than SC10. Conclusions and clinical relevance MMK combinations containing either 7 or 10 mg kg−1 ketamine and given IM are suitable combinations for anaesthetising ferrets, although the observed degree of hypoxaemia indicates that oxygen administration is vital.

Introduction Low levels of C1-esterase inhibitor (C1-INH) and concomitant reduced complement 4 (C4) concentrations have been identified in patients with hereditary angioedema (HAE). C4 constitutes a promising candidate for a biomarker of disease activity. This investigation aims to determine the relationship between C1-INH functional activity levels (C1-INH[f]) and C4 antigen concentrations in patients with HAE treated with subcutaneous (SC) C1-INH, inferring significance for clinical practice. Methods C1-INH(f) and C4 antigen levels were assayed in three clinical studies (NCT01576523, NCT01912456, NCT02316353 [COMPACT Phase 2, 3 and open-label extension studies]). The relationship between these measurements was inspected in an exploratory manner. All measurements were performed at a central laboratory using validated assays and investigated with respect to time after C1-INH(SC) administration and HAE type. C4 antigen concentration over time after C1-INH(SC) administration was characterized, and the correlation with C1-INH(f) evaluated. Results C4 antigen concentration increased gradually following C1-INH(SC) administration until ∼100 hours post-administration when concentrations declined. A linear relationship was observed between C4 antigen concentrations and C1-INH(f) in patients with type I HAE, based on the Loess fit, until C1-INH(f) of ∼50%, at which point signs of saturability became apparent (example figure shown). The relationship in patients with type II HAE was not clear. Conclusions An exploratory analysis showed a linear relationship between C1-INH(f) and C4 antigen levels in patients with type I HAE, consistent with previous reports. The interplay between C1-INH(f) and C4 should be further explored to understand the potential role of C4 monitoring in treatment decision-making.

Introduction Elderly patients ≥65 years old with hereditary angioedema (HAE) type I/II due to C1-inhibitor (C1-INH) deficiency may have an altered response to treatment and be at higher risk for treatment-related adverse events (AEs) due to comorbidities and polypharmacy. Subcutaneous (SC) C1-INH is indicated for routine prophylaxis to prevent HAE attacks in adolescents and adults. This post-hoc analysis examined the efficacy and safety of C1-INH (SC) in patients ≥65 years old treated in an open-label extension study. Methods Eligible patients (entry criteria: ≥6 years old, ≥4 attacks/8-week interval) were treated with C1-INH (SC) 40 or 60 IU/kg twice weekly and studied for ≤140 weeks. For this analysis, patients were stratified by age ( Results Of 126 patients, 10 were ≥65 years old (mean age [range], 68 years [65-72]; mean duration of treatment, 80 weeks). Elderly patients had a >70% median reduction in attacks relative to their attack rate prior to randomization, with 3 patients being completely attack free for up to 2.4 years. Overall, the most frequently reported AEs were nasopharyngitis, injection-site reactions, headache, and upper respiratory tract infection. No thromboembolic event was reported in these elderly patients. Conclusions C1-INH (SC) is safe and effective for long-term prophylaxis of HAE attacks in elderly patients aged ≥65. These findings are consistent with those from the COMPACT phase III study.

Introduction In women with hereditary angioedema (HAE) due to C1-inhibitor (C1-INH) deficiency, pregnancy can have a variable effect on disease activity. C1-INH concentrate is recommended as first-line therapy for pregnant patients with HAE. Subcutaneous C1-INH (HAEGARDA®, CSL Behring) is indicated for routine prophylaxis to prevent HAE attacks in adolescents and adults. This analysis examines outcomes in patients who became pregnant during C1-INH (SC) treatment in an open-label safety study. Methods Per study protocol, patients who became pregnant during treatment were required to discontinue the study. These patients were assessed during exposure to C1-INH in the open-label study and followed post-discontinuation to assess pregnancy outcomes. Results Four patients discontinued the study due to pregnancy as mandated by the protocol. C1-INH (SC) exposure after the last menstrual period ranged from 4 to 8 weeks (9, 10, 10, and 15 doses). Pregnancy was normal in all cases, with no related complications. All 4 women delivered live healthy infants, 1 by vaginal delivery and 3 by caesarean section at 36 to 40 weeks gestation. No congenital abnormalities were reported. With twice-weekly C1-INH (SC) treatment in the open-label study (total exposure: 25.3-43.1 weeks), 3 women had ≥50% reduction in HAE attacks relative to the number used to qualify for study entry. Three patients had Conclusions In this study, patients with HAE who were exposed to C1-INH (SC) during the first trimester of pregnancy had normal pregnancy outcomes, and all delivered healthy newborns.

Background Hereditary angioedema with C1-inhibitor deficiency (C1-INH-HAE) impairs health-related quality of life (HRQoL). Objective The objective of this study was to assess HRQoL outcomes in patients self-administering subcutaneous C1-INH (C1-INH[SC]; HAEGARDA) for routine prevention of HAE attacks. Methods Post hoc analysis of data from the placebo-controlled, crossover phase III COMPACT study (Clinical Studies for Optimal Management of Preventing Angioedema with Low-Volume Subcutaneous C1-Inhibitor Replacement Therapy). Ninety patients with C1-INH-HAE were randomized to 1 of 4 treatment sequences: C1-INH(SC) 40 or 60 IU/kg twice weekly for 16 weeks, preceded or followed by 16 weeks of twice weekly placebo injections. All HAE attacks were treated with open-label on-demand treatment as necessary. HRQoL assessments at week 14 (last visit) included the European Quality of Life-5 Dimensions Questionnaire (EQ-5D-3L), the Hospital Anxiety and Depression Scale (HADS), the Work Productivity and Activity Impairment Questionnaire (WPAI), and the Treatment Satisfaction Questionnaire for Medication (TSQM). Results Compared with placebo (on-demand treatment alone), treatment with twice weekly C1-INH(SC) (both doses combined) was associated with better EQ-5D visual analog scale general health, less HADS anxiety, less WPAI presenteeism, work productivity loss, and activity impairment, and greater TSQM effectiveness and overall treatment satisfaction. More patients self-reported a "good/excellent" response during routine prevention with C1-INH(SC) compared with on-demand only (placebo prophylaxis) management. For each HRQoL measure, a greater proportion of patients had a clinically meaningful improvement during C1-INH(SC) treatment compared with placebo. Conclusions In patients with frequent HAE attacks, a treatment strategy of routine prevention with self-administered twice weekly C1-INH(SC) had a greater impact on improving multiple HAE-related HRQoL impairments, most notably anxiety and work productivity, compared with on-demand treatment alone (placebo prophylaxis).

The objective of this study was to characterize the thrombogenicity of one pasteurized fibrinogen concentrate (Haemocomplettan P) in clinical use for over 20 years. Thrombus formation during venous stasis was assessed in rabbits receiving either 100 or 250 mg/kg Haemocomplettan P. Thrombotic adverse events possibly related to Haemocomplettan P were documented in a long-standing pharmacosurveillance program. A systematic review of thrombotic events in Haemocomplettan P clinical studies was also conducted. There was no evidence of thrombus formation during venous stasis in any Haemocomplettan P-treated animal. The pharmacosurveillance program spanned 22 years, during which a Haemocomplettan P quantity equivalent to more than 250 000 doses of 4 g each was distributed in 21 countries. Nine spontaneous reports of thrombotic adverse events possibly related to Haemocomplettan P were compiled, corresponding to an incidence rate of 3.48 events per 10 treatment episodes (95% confidence interval, 1.59-6.61 events per 10 treatment episodes). In 10 clinical studies involving 298 patients, one patient developed nonfatal venous thrombosis and pulmonary embolism to which fibrinogen concentrate may have contributed. Additionally, four other patients experienced arterial ischemic events that were likely attributable to massive hemorrhage and hypotension rather than fibrinogen replacement. Evidence from an animal model of venous stasis, a comprehensive pharmacosurveillance program, and a systematic review of clinical studies indicates that the thrombogenic potential of fibrinogen concentrate is low.

Haemostasis including blood coagulation is initiated upon vessel wall injury and indispensable to limit excessive blood loss. However, unregulated pathological coagulation may lead to vessel occlusion, causing thrombotic disorders, most notably myocardial infarction and stroke. Furthermore, blood exposure to foreign surfaces activates the intrinsic pathway of coagulation. Hence, various clinical scenarios, such as extracorporeal membrane oxygenation, require robust anticoagulation consequently leading to an increased bleeding risk. This study aimed to further assess the antithrombotic efficacy of the activated factor XII (FXIIa) inhibitor, rHA-Infestin-4, in several thrombosis models. In mice, rHA-Infestin-4 decreased occlusion rates in the mechanically-induced arterial (Folt's) and the FeCl3 -induced venous thrombosis model. rHA-Infestin-4 also protected from FeCl3 -induced arterial thrombosis and from stasis-prompted venous thrombosis in rabbits. Furthermore, rHA-Infestin-4 prevented occlusion in the arterio-venous shunt model in mice and rabbits where thrombosis was induced via a foreign surface. In contrast to heparin, the haemostatic capacity in rabbits was unaffected by rHA-Infestin-4. Using rodent and non-rodent species, our data demonstrate that the FXIIa inhibitor rHA-Infestin-4 decreased arterial, venous and foreign surface-induced thrombosis without affecting physiological haemostasis. Hence, we provide further evidence that targeting FXIIa represents a potent yet safe antithrombotic treatment approach, especially in foreign surface-triggered thrombosis.

Treatment of von Willebrand disease typically requires multiple infusions of von Willebrand factor (VWF)/factor VIII (FVIII) concentrate. Accumulation of FVIII is a clinical concern due to potential risk for thromboembolism. This study sought to determine whether VWF/FVIII concentrate of high VWF:FVIII ratio can prevent FVIII accumulation. VWF-deficient knockout mice received four 150 IU/kg VWF:ristocetin cofactor (RCo) infusions at 3-h intervals, with VWF/FVIII concentrates of a high (Haemate P/Humate-P) or low (Wilate) VWF:FVIII ratio. After each infusion, trough FVIII and VWF levels in plasma were determined. Separately, pharmacokinetic analysis was performed after single 250-IU/kg VWF:RCo infusions of each concentrate. Over the course of the four infusions, trough FVIII increased significantly in the group receiving Wilate (P

Local photodynamic therapy was used to prevent neointimal hyperplasia after stenting. Slotted tube stents were placed with 16 atmospheres in porcine femoral arteries with the external diameter to match the diameter at 10 atmospheres. Animals were randomly allocated to Group 1 (stenting only); or Group 2 with stenting, local drug delivery of a photosensitizer (5 mg Photofrin) and subsequent exposure to light (photodynamic therapy, 100 J). Fourteen days later, all vessels were excised, fixed and processed for histology. Tissue hyperplasia was observed after stenting in vessels from Group 1. In Group 2 with photodynamic therapy, the myoproliferative response was significantly reduced. Tissue hyperplasia after stenting was effectively suppressed by photodynamic therapy.

Background: Edoxaban is an oral, selective direct factor Xa inhibitor approved in Japan for venous thromboembolism prevention after orthopedic surgery. Data are lacking regarding reversal strategies for edoxaban; this study assessed whether four-factor prothrombin complex concentrate (Beriplex®/Kcentra®; CSL Behring GmbH, Marburg, Germany) can effectively reverse its effects on hemostasis using a previously described rabbit model. Methods: The study comprised assessments of thrombin generation in vitro, pharmacokinetic parameters, and edoxaban reversal in vivo. In a blinded in vivo stage, a standardized kidney incision was performed in animals (n = 11 per group) randomized to receive vehicle + saline, edoxaban (1,200 μg/kg) + saline, or edoxaban (1,200 μg/kg) + four-factor prothrombin complex concentrate (50 IU/kg). Animals were monitored for treatment impact on hemostasis and coagulation parameters. Data are median (range). Statistical tests were adjusted for multiple testing. Results: Edoxaban administration increased blood loss (30 [2 to 44] ml) and time to hemostasis (23 [8.5 to 30.0] min) compared with the control group (3 [1 to 8] ml and 3 [2.0 to 5.0] min, respectively). Biomarkers of coagulation (prothrombin time, activated partial thromboplastin time, whole blood clotting time) and thrombin generation parameters (e.g., peak thrombin, endogenous thrombin potential, lag time) were also affected by edoxaban. Administration of four-factor prothrombin complex concentrate significantly reduced time to hemostasis (to 8 [6.5 to 14.0] min, observed P < 0.0001) and total blood loss (to 9 [4 to 22] ml, observed P = 0.0050) compared with the edoxaban + saline group. Of the biomarkers tested, prothrombin time, whole blood clotting time, and endogenous thrombin potential correlated best with clinical parameters. Conclusion: In a rabbit model of hemostasis, four-factor prothrombin complex concentrate administration significantly decreased edoxaban-associated hemorrhage.

SummaryFactor VII (FVII) activating protease (FSAP) is a circulating protease with a putative function in blood coagulation and fibrinolysis. Genetic epidemiological studies have implied a role for FSAP in carotid stenosis, stroke and thrombosis. To date, no in vivo evidence is available to support these claims. We have, for the first time, used FSAP-/- mice to define its role in thrombosis and haemostasis in vivo and to characterise the molecular mechanisms involved. FeCl3–induced arterial thrombosis in carotid and mesenteric artery revealed that the occlusion time was significantly increased in FSAP-/- mice (p< 0.01) and that some FSAP-/- mice did not occlude at all. FSAP-/- mice were protected from lethal pulmonary thromboembolism induced by collagen/ epinephrine infusion (p< 0.01). Although no spontaneous bleeding was evident, in the tail bleeding assay a re-bleeding pattern was observed in FSAP-/- mice. To explain these observations at a mechanistic level we then determined how haemostasis factors and putative FSAP substrates were altered in FSAP-/- mice. Tissue factor pathway inhibitor (TFPI) levels were higher in FSAP-/- mice compared to WT mice whereas FVIIa levels were unchanged. Other coagulation factors as well as markers of platelet activation and function revealed no significant differences between WT and FSAP-/- mice. This phenotype of FSAP-/- mice could be reversed by application of exogenous FSAP. In conclusion, a lack of endogenous FSAP impaired the formation of stable, occlusive thrombi in mice. The underlying in vivo effect of FSAP is more likely to be related to the modulation of TFPI rather than FVIIa.

Introduction In vivo animal data have shown prothrombin complex concentrate (PCC) to be effective in preventing bleeding induced by excessive plasma levels of the direct thrombin inhibitor dabigatran. This animal model study was designed to determine the risk of thrombosis associated with administration of a PCC (Beriplex P/N) to reverse dabigatran-induced bleeding. Materials and methods Anesthetized rabbits were treated with initial 0, 75, 200 or 450μgkg -1 dabigatran boluses followed by continuous infusions to maintain elevated plasma dabigatran levels. At 15min after the start of dabigatran administration, PCC doses of 0, 50 or 300IUkg -1 were administered. Thereafter, coagulation in an arteriovenous (AV) shunt was evaluated and histopathologic examination for thrombotic changes performed. Venous thrombosis was also assessed in a modified Wessler model. Results At the suprapharmacologic dose of 300IUkg -1 , PCC increased thrombus weight during AV shunting, but this effect could be prevented by dabigatran at all tested doses. AV shunt occlusion after PCC administration was delayed by 75μgkg -1 dabigatran and abolished by progressively higher dabigatran doses. High-dose treatment with 300IUkg -1 PCC resulted in histologically evident low-grade pulmonary thrombi; however, that effect could be blocked by dabigatran in a dose-dependent manner (p=0.034). In rabbits treated with high-dose PCC, dabigatran inhibited thrombus formation during venous stasis. PCC effectively reversed dabigatran-induced bleeding. Conclusions In this animal study, thrombosis after PCC administration could be prevented in the presence of dabigatran. PCC reversed dabigatran-induced excessive bleeding while retaining protective anticoagulatory activity of dabigatran.

Currently used anticoagulants prevent thrombosis but increase bleeding. We show an anticoagulation therapy without bleeding risk based on a plasma protease factor XII function-neutralizing antibody. We screened for antibodies against activated factor XII (FXIIa) using phage display and demonstrated that recombinant fully human antibody 3F7 binds into the FXIIa enzymatic pocket. 3F7 interfered with FXIIa-mediated coagulation, abolished thrombus formation under flow, and blocked experimental thrombosis in mice and rabbits. We adapted an extracorporeal membrane oxygenation (ECMO) cardiopulmonary bypass system used for infant therapy to analyze clinical applicability of 3F7 in rabbits. 3F7 provided thromboprotection as efficiently as heparin, and both drugs prevented fibrin deposition and thrombosis within the extracorporeal circuit. Unlike heparin, 3F7 treatment did not impair the hemostatic capacity and did not increase bleeding from wounds. These data establish that targeting of FXIIa is a safe mode of thromboprotection in bypass systems, and provide a clinically relevant anticoagulation strategy that is not complicated by excess bleeding.

Cardiac myocyte apoptosis has been demonstrated in end-stage failing human hearts. The therapeutic utility of blocking apoptosis in congestive heart failure (CHF) has not been elucidated. This study investigated the role of caspase activation in cardiac contractility and sarcomere organization in the development of CHF. In a rabbit model of heart failure obtained by rapid ventricular pacing, we demonstrate, using in vivo transcoronary adenovirus-mediated gene delivery of the potent caspase inhibitor p35, that caspase activation is associated with a reduction in contractile force of failing myocytes by destroying sarcomeric structure. In this animal model gene transfer of p35 prevented the rise in caspase 3 activity and DNA-histone formation. Genetically manipulated hearts expressing p35 had a significant improvement in left ventricular pressure rise (+dp/dt), decreased end-diastolic chamber pressure (LVEDP), and the development of heart failure was delayed. To better understand this benefit, we examined the effects of caspase 3 on cardiomyocyte dysfunction in vitro. Microinjection of activated caspase 3 into the cytoplasm of intact myocytes induced sarcomeric disorganization and reduced contractility of the cells. These results demonstrate a direct impact of caspases on cardiac function and may lead to novel therapeutic strategies via antiapoptotic regimens.

Introduction rVIII-SingleChain (CSL627), a novel recombinant coagulation factor VIII (FVIII), is under investigation in a phase I/III clinical programme (AFFINITY) for the treatment of haemophilia A. Non-clinical studies were conducted to investigate the pharmacokinetic/pharmacodynamic profile of rVIII-SingleChain in comparison with full-length recombinant FVIII. Materials and Methods Binding affinity of rVIII-SingleChain for von Willebrand factor was investigated by surface plasmon resonance analysis. The pharmacokinetic profile of rVIII-SingleChain was compared with a marketed full-length recombinant FVIII concentrate (Advate ® ) in haemophilia A mice, von Willebrand factor knock-out mice, Crl:CD (SD) rats, rabbits and cynomolgus monkeys. Systemic FVIII activity or antigen levels were recorded. Procoagulant activity was measured in an FeCl 3 -induced arterial occlusion model and by recording thrombin generation activity (ex vivo) after administration of 200–250IU/kg rVIII-SingleChain or full-length FVIII to haemophilia A mice. Results rVIII-SingleChain displayed a high affinity for von Willebrand factor (K D =44pM vs. 139 pM for full-length recombinant FVIII). In all animal species tested, rVIII-SingleChain had more favourable pharmacokinetic properties than full-length recombinant FVIII: clearance was decreased and area under the curve and terminal half-life were enhanced vs. full-length recombinant FVIII, while in vivo recovery and volume of distribution were equivalent. rVIII-SingleChain showed a prolonged thrombin generation potential and prolonged procoagulant activity vs. full-length recombinant FVIII in an FeCl 3 -induced arterial occlusion model. Conclusions rVIII-SingleChain had a higher affinity for von Willebrand factor than full-length recombinant FVIII and displayed favourable pharmacokinetic/pharmacodynamic properties in non-clinical models.

Objective— The ability of high-density lipoprotein (HDL) to remove cholesterol from atherosclerotic plaque is thought to underlie its inverse correlation with cardiovascular risk. Our objective was to produce and characterize a human apolipoprotein AI (apoA-I) product optimized to treat clinical atherosclerotic disease. Approach and Results— A new formulation of full length, plasma-derived human apoA-I termed CSL112 was designed to maximize the cholesterol efflux from cells and exhibit favorable pharmacological properties. CSL112 is a disc-shaped particle that strongly elevates cholesterol esterification and shows good pharmacokinetics in rabbits. Infusion of CSL112 into rabbits caused a strong and immediate increase in the ATP binding cassette transporter A1 (ABCA1)-dependent efflux capacity of plasma, an increase in plasma unesterified cholesterol and rapid subsequent cholesterol esterification. In the presence of human plasma, CSL112 was significantly more potent than native HDL at enhancing cholesterol efflux from macrophages, and the efflux elevation was predominantly via the ABCA1 transporter. Consistent with this observation, addition of CSL112 to plasma led to generation of high levels of HDL-VS, a favorable substrate for ABCA1. The lipid profile of plasma did not affect these behaviors. In studies with whole human blood, CSL112 reduced expression of intercellular adhesion molecule 1 and cytokine secretion, and as with cholesterol efflux, these activities were substantially greater than those of native HDL assayed in parallel. Conclusions— CSL112 has favorable pharmacological properties and strongly elevates the ability of plasma to withdraw cholesterol from cells. Preferential elevation of ABCA1-dependent efflux may target atherosclerotic plaque for cholesterol removal and this property makes CSL112 a promising candidate therapy for acute coronary syndrome.

Background and objectives Activated clotting factor FXI (FXIa) has been postulated to play a significant role in thromboembolic events potentially associated with the administration of intravenous immunoglobulin. The purpose of this study was to demonstrate that thrombogenic agents, in particular FXIa and FXI, are depleted or inactivated in Privigen®. Materials and methods The ability of the purification process to deplete FXIa from plasma was studied. All steps of the Privigen® production were investigated for potential activation of FXI to FXIa with spiking experiments. Results Privigen® contains no procoagulant activity as determined by FXIa chromogenic assay, non-activated partial thromboplastin time (NaPTT) and thrombin generation assays (TGA, FXIa-like activity). The coagulation times were >200 s in the NaPTT test. FXIa was below the detection limit of 0·14 ng/ml (chromogenic assay) and below the quantification limit of 0·2 ng/ml (TGA). FXIa spiking experiments showed that the analytical methods used can detect traces of procoagulant activity in immunoglobulin samples. FXIa spiking and kinetic experiments during the octanoic acid fractionation step showed that a substantial reduction in FXIa specific activity (by ≥99·9% within 40 min of octanoic acid incubation) was reached already at an early stage of the manufacturing process. These results were confirmed in vivo: in a modified Wessler test, no thrombus was reported. Conclusion The Privigen® manufacturing process has the capability to remove thrombogenic factors: octanoic acid precipitation, designed to remove a variety of contaminants during immunoglobulin purification, also removes almost all FXIa from plasma and further purification steps do not activate FXI.

Summary. Background: Prophylaxis of hemophilia B, at present, requires multiple infusions of human factor (F)IX concentrates per week. A FIX molecule with a prolonged half-life has the potential to greatly improve the convenience of, and adherence to, prophylaxis. Objectives: The aim of our studies was to investigate the pharmacokinetic (PK) and pharmacodynamic (PD) profile of a recombinant fusion protein linking coagulation FIX with albumin (rIX-FP). Methods: Cynomolgus monkeys and hemophilia B dogs received single intravenous doses of rIX-FP (50–500 IU kg−1). rIX-FP plasma levels were determined by an activity-based assay (dogs only) and anti-FIX ELISA methods. Additionally, activated partial thromboplastin time (APTT) was determined in hemophilia B dogs. Data were compared with a direct study comparator (recombinant FIX [rFIX]) or previously published data. Results: The terminal half-life of rIX-FP was prolonged in both species compared with FIX reference data. In hemophilia B dogs, human FIX antigen levels remained above 0.05 IU mL−1 more than three times longer after rIX-FP (7.3 days) compared with rFIX (2.3 days), whereas respective calculations based on activity levels confirmed the observed superior profile. Prolonged PDs of rIX-FP were demonstrated with APTT

Background Extracorporeal circuit priming and intravascular volume expansion during cardiopulmonary bypass (CPB) may lead to dilutional coagulopathy and excessive diffuse postoperative bleeding. Prothrombin complex concentrate (PCC) containing clotting factors II (FII), VII (FVII), IX (FIX), and X (FX) could be of potential value in correcting dilutional coagulopathy and reducing blood loss. Methods Anaesthetized pigs underwent CPB with hypothermia for 2 h at 25°C followed by 1 h of normothermia. Approximately 1 h after CPB, animals randomly received either isotonic saline 1 ml kg −1 or PCC 30 IU kg −1 in a volume of 1 ml kg −1 . Diffuse coagulopathic bleeding was assessed as suture hole blood loss from a Gore-Tex patch placed over a full-thickness incision in the left carotid artery. Results After CPB, levels of FII, FVII, FIX, and FX declined from baseline by 32% to 48%, and PCC fully or partially reversed those deficits. Median suture hole blood loss after administration of saline placebo was 74 ml. PCC reduced suture hole bleeding by a median of 54 ml with a 95% confidence interval of 6–112 ml ( P =0.026) compared with saline. PCC, but not saline, normalized skin bleeding time. Peak thrombin generation markedly decreased after CPB, but then returned in PCC-treated animals to a level higher than baseline by 28.7 nM (14.5–41.1 nM; P =0.031). Conclusions PCC was effective in correcting dilutional coagulopathy and reducing diffuse bleeding in an in vivo large-animal CPB model. Further research is warranted on PCC as a haemostatic agent in CPB.

Introduction Fluid resuscitation after trauma often results in dilutional coagulopathy that may hinder control of bleeding and, once initial hemostasis has been secured, heighten risk of perioperative bleeding when further surgery is required. Since multiple coagulation factor deficiencies typically accompany fluid resuscitation, prothrombin complex concentrate (PCC) containing factors II, VII, IX and X may potentially offer greater hemostatic efficacy than coagulation factor monotherapy. Materials and methods Anesthetized normothermic rabbits were hemodiluted 50-60% by phased blood withdrawal and infusion of hydroxyethyl starch and erythrocytes. The animals were randomly assigned to receive saline placebo, 25 IU·kg - 1 PCC (Beriplex P/N) or 180 μg·kg - 1 activated recombinant factor VII (rFVIIa; NovoSeven). Immediately thereafter, bleeding was precipitated by a standardized kidney incision. Results PCC accelerated hemostasis compared both with saline and rFVIIa (p = 0.002 for both comparisons). The median times to hemostasis in the PCC, saline and rFVIIa groups were 12, 19 and 28 min, respectively. PCC reduced blood loss by a median of 43 mL with a 95% confidence interval (CI) of 8.0-67.5 mL vs. saline and 82 mL (CI, 35.0-110.0 mL) vs. rFVIIa. PCC augmented peak thrombin generation by a median of 104.1 n M (CI, 78.3-142.3 n M ) compared with saline and 105.8 n M (CI, 70.7-139.5 n M ) relative to rFVIIa. At the respective 180 μg·kg - 1 and 25 IU·kg - 1 doses tested, rFVIIa displayed thrombogenicity in the Wessler stasis model, while PCC did not. Conclusions In an animal model of dilutional coagulopathy and kidney trauma, PCC accelerated hemostasis and diminished blood loss compared with rFVIIa monotherapy.

Abstract —In heart failure, reduced cardiac contractility is accompanied by blunted cAMP responses to β-adrenergic stimulation. Parathyroid hormone (PTH)–related peptide and arginine vasopressin are released from the myocardium in response to increased wall stress but do not stimulate contractility or adenylyl cyclase at physiological concentrations. To bypass the defective β-adrenergic signaling cascade, recombinant P1 PTH/PTH-related peptide receptors (rPTH1-Rs) and V 2 vasopressin receptors (rV 2 -Rs), which are normally not expressed in the myocardium and which are both strongly coupled to adenylyl cyclase, and recombinant β 2 -adrenergic receptors (rβ 2 -ARs) were overexpressed in cardiomyocytes by viral gene transfer. The capacity of endogenous hormones to increase contractility via the heterologous, recombinant receptors was compared. Whereas V 2 -Rs are uniquely coupled to Gs, PTH1-Rs and β 2 -ARs are also coupled to other G proteins. Gene transfer of rPTH1-Rs or rβ 2 -ARs to adult cardiomyocytes resulted in maximally increased basal contractility, which could not be further stimulated by adding receptor agonists. Agonists at rPTH1-Rs induced increased cAMP formation and phospholipase C activity. In contrast, healthy or failing rV 2 -R–expressing cardiomyocytes showed unaltered basal contractility. Their contractility and cAMP formation increased only at agonist exposure, which did not activate phospholipase C. In summary, we found that gene transfer of PTH1-Rs to cardiomyocytes results in constitutive activity of the transgene, as does that of β 2 -ARs. In the absence of receptor agonists, rPTH1-Rs and rβ 2 -ARs increase basal contractility, coupling to 2 G proteins simultaneously. In contrast, rV 2 -Rs are uniquely coupled to Gs and are not constitutively active, retaining their property to be activated exclusively on agonist stimulation. Therefore, gene transfer of V 2 -Rs might be more suited to test the effects of cAMP-stimulating receptors in heart failure than that of PTH1-Rs or β 2 -ARs.

This study was designed to determine whether the four-factor Prothrombin Complex Concentrate (4-PCC) Beriplex® P/N (Kcentra™) can effectively reverse bleeding following edoxaban administration in a rabbit kidney injury model. The oral direct and selective factor Xa inhibitor edoxaban (Daiichi Sankyo) is currently available in Japan for the prophylaxis of venous thromboembolism (VTE) in patients undergoing major orthopedic surgery and is undergoing investigation in phase III trials for the prevention of stroke in patients with atrial fibrillation and the treatment and secondary prevetion of VTE. The primary complication of any available anticoagulant therapy is the risk of bleeding. Rapid reversal of anticoagulation may be necessary in patients requiring emergency treatment due to uncontrolled bleeding. PCCs are frequently used to reverse the effect of vitamin K antagonists such as warfarin and have also been suggested to be potentially effective in reversing the effects of the new oral anticoagulants. The present study was therefore designed to further investigate the ability of 4-PCC to reverse the anticoagulant action of edoxaban using an in vivo rabbit model of acute bleeding. Animals were treated with a high intravenous bolus dose of edoxaban (1200 µg/kg) leading to increased and prolonged bleeding following standardized kidney injury compared to vehicle administration. Parallel monitoring of biomarkers of haemostasis showed that edoxaban treatment resulted in the prolongation of prothrombin time (PT), activated partial thromboplastin time, and whole blood clotting time (WBCT), and affected the thrombin generation parameters thrombin peak, endogenous thrombin potential (ETP), lagtime and time to peak. Subsequent administration of the 4-PCC (25-75 IU/kg) resulted in a dose-dependent reversal of edoxaban induced bleeding as indicated by reduced time to haemostasis and total blood loss. Both parameters achieved statistical significance compared to placebo at the 4-PCC dose of 50 IU/kg under fully blinded study conditions. The biomarkers correlating best with 4-PCC mediated edoxaban anticoagulation reversal included PT, WBCT and ETP. In summary, 4-PCC treatment effectively decreased edoxaban induced hemorrhage in an animal model of acute bleeding at clinically relevant dose levels. Disclosures: Herzog: CSL Behring GmbH: Employment. Kaspereit:CSL Behring GmbH: Employment. Krege:CSL Behring GmbH: Employment. Pragst:CSL Behring GmbH: Employment. Morishima:Daiichi Sankyo: Employment. Schulte:CSL Behring GmbH: Employment. Dickneite:CSL Behring GmbH: Employment.

Abstract 1115 Recombinant factor VIIa (rFVIIa) is approved to control bleeding in hemophilia A and B patients who have developed inhibitory antibodies to replacement therapy and in acquired hemophilia. rFVIIa is rapidly eliminated with a terminal half-life of approximately 2.5 hours in humans. This short half life necessitates frequent injections and considerably limits prophylactic use. A recombinant fusion protein linking activated factor VII with albumin (rVIIa-FP) was engineered to extend the half life of rFVIIa. The present studies were conducted to gather knowledge about the pharmacokinetic and pharmacodynamic (PK/PD) properties of rVIIa-FP in preclinical animals models to enable a more precise estimate of the procoagulant activity of rVIIa-FP for the future clinical use in haemophilia patients with inhibitors to FVIII and FIX. Single intravenous doses of either rVIIa-FP or the licensed rFVIIa comparator, NovoSeven® were administered to mice, rabbits and monkeys. Subsequently, plasma samples were harvested at different time-points after study drug administration and systemic levels of rVIIa-FP or NovoSeven® were assessed either by FVIIa activity measurements using the Staclot® assay system or by FVII antigen measurements using an enzyme linked immunoabsorbance assay (ELISA). When investigating dose responses or duration of hemostatic activity, rVIIa-FP and NovoSeven® were administered to mice or rabbits before tail clip or induction of venous stasis, respectively. Following a single intravenous bolus application the procoagulant activity of both study drugs was assessed in both models at different time points after administration up to 24 hours to proof prolonged procoagulant effects of rVIIa-FP compared to NovoSeven®. Intriguingly, in all animal species tested the systemic bioavailability, clearance and in addition the terminal half-life (t1/2β), of rVIIa-FP were significantly better in comparison to NovoSeven®. Based on FVIIa activity measurements in plasma samples derived from monkeys the 11 fold higher area under the curve (AUC) was accompanied with a 4-fold longer t1/2β, while in vivo recovery (IVR) of rVIIa-FP exceeded that of NovoSeven® by a 70 %. In rabbits the 20 fold higher AUC was associated with a 5-fold longer t1/2β and a 4-fold higher IVR when measuring specific FVIIa activity. In mice measurements of FVII antigen revealed a 11 fold higher AUC, while t1/2β was 4 times longer and IVR was found to be doubled in comparison to NovoSeven®. The assessment of pharmacodynamic activity after dosing based on specific FVIIa activity adjusted by the Staclot® assay revealed, that the procoagulant effect of rVIIa-FP was not different from NovoSeven®, when measuring total blood loss under acute bleeding conditions after tail clip. However, when assessing late time-points after treatment the prolonged systemic availability of rVIIa-FP translated into a longer and sustained hemostatic activity of rVIIa-FP compared to NovoSeven® in both animal models. Intriguingly, ex vivo studies in hemophilia A mice showed that the 4 fold prolonged systemic availability of rVIIa-FP in plasma translates into sustained FVIIa activity when recorded as thrombin generation activity compared to NovoSeven® at 16 hours after treatment. Furthermore in rabbits, the 5 fold longer half-life translated into a significantly greater procoagulant activity as measured by thrombus formation in both jugular veins after venous stasis. In conclusion, the recombinant albumin fusion technology was successfully applied to human recombinant FVIIa for a significantly improved of PK/PD profile as observed in different pre-clinical animal species. Future clinical studies can proof whether the observed improved PK/PD characteristics will also translate into a half-life extension and a longer hemostatic effect in hemophilia patients with inhibitors to FVIII and FIX. Allowed: The entire body of the abstract, including text and tables, must not exceed 3,800 characters. Spaces are not included in this number; title, authors' names, and affiliations are counted separately. Figures are not included in the character count. Disclosures: Zollner: CSL Behring GmbH: Employment. Schuermann:CSL Behring GmbH: Employment. Raquet:CSL Behring GmbH: Employment. Mueller-Cohrs:CSL Behring GmbH: Employment. Weimer:CSL Behring GmbH: Employment. Pragst:CSL Behring GmbH: Employment. Dickneite:CSL Behring GmbH: Employment. Schulte:CSL Behring GmbH: Employment.