Evaluation of Factor VIII Polysialylation: Identification of a Longer-Acting Experimental Therapy in Mice and Monkeys.

Extended half-life (EHL) factor therapies are needed to reduce the burden of prophylaxis and improve treatment adherence in patients with hemophilia. BAX 826 is a novel polysialylated full-length recombinant factor VIII [polysialyic acid (PSA) rFVIII] with improved pharmacokinetics (PK), prolonged pharmacology, and maintained safety attributes to enable longer-acting rFVIII therapy. In factor VIII (FVIII)-deficient hemophilic mice, PSArFVIII showed a substantially higher mean residence time (>2-fold) and exposure (>3-fold), and prolonged efficacy in tail-bleeding experiments (48 vs. 30 hours) compared with unmodified recombinant FVIII (rFVIII), as well as a potentially favorable immunogenicity profile. Reduced binding to a scavenger receptor (low-density lipoprotein receptor-related protein 1) and von Willebrand factor (VWF) as well as a largely VWF-independent circulation time in mice provide a rationale for prolonged BAX 826 activity. The significantly improved PK profile versus rFVIII was confirmed in cynomolgus monkeys [mean residence time: 23.4 vs. 10.1 hours; exposure (area under the curve from time 0 to infinity): 206 vs. 48.2 IU/ml⋅h] and is in line with results from rodent studies. Finally, safety and toxicity evaluations did not indicate increased thrombogenic potential, and repeated administration of BAX 826 to monkeys and rats was well tolerated. The favorable profile and mechanism of this novel experimental therapeutic demonstrated all of the requirements for an EHL-rFVIII candidate, and thus BAX 826 was entered into clinical assessment for the treatment of hemophilia A. SIGNIFICANCE STATEMENT: Prolongation of FVIII half-life aims to reduce the burden of prophylaxis and improve treatment outcomes in patients with hemophilia. This study shows that polysialylation of PSArFVIII resulted in prolongations of rFVIII circulation time and procoagulant activity, together with a favorable nonclinical safety profile of the experimental therapeutic.

Efficacy and safety of prophylaxis with BAY 81-8973 in Chinese patients with severe haemophilia A enrolled in the LEOPOLD II trial.

INTRODUCTION: BAY 81-8973 (Kovaltry® ) is a full-length, unmodified recombinant human factor VIII approved in China for prophylaxis and on-demand treatment in patients with haemophilia A. Limited access to FVIII prophylaxis in China has historically led to this population being undertreated. This subanalysis of LEOPOLD II investigated whether the efficacy and safety of BAY 81-8973 varied between Chinese and non-Chinese patients. AIM: To evaluate BAY 81-8973 efficacy and safety in Chinese patients. METHODS: LEOPOLD II enrolled males aged 12-65 years with severe haemophilia A who were receiving on-demand treatment. Patients were randomly assigned to receive BAY 81-8973 as low-dose prophylaxis (20-30 IU/kg twice-weekly), high-dose prophylaxis (30-40 IU/kg 3 times weekly) or on-demand for 1 year. RESULTS: Data were available from 23 Chinese and 57 non-Chinese patients; Chinese patients had a higher prestudy bleeding rate and were more likely to have target joints than non-Chinese patients. 74% of patients were assigned to prophylaxis. Annualized bleeding rates (ABRs) in Chinese and non-Chinese patients receiving prophylaxis were significantly lower compared to patients treated on-demand. Median ABRs for all bleeds in the last 6 months of the study were 2.0 and 1.0 for Chinese and non-Chinese patients, respectively, in the combined prophylaxis groups, and 61.3 and 58.5 in the on-demand group. A treatment-related adverse event occurred in 1 Chinese patient; no patients developed FVIII inhibitors. CONCLUSION: BAY 81-8973 prophylaxis was efficacious and well tolerated in Chinese patients with severe haemophilia A, with ABRs comparable to those in non-Chinese patients receiving prophylaxis.

BAY 94-9027, a PEGylated recombinant factor VIII, exhibits a prolonged half-life and higher area under the curve in patients with severe haemophilia A: Comprehensive pharmacokinetic assessment from clinical studies.

INTRODUCTION: Recombinant factor VIII (rFVIII) products with extended half-lives, such as BAY 94-9027, can potentially maintain higher FVIII levels for longer periods of time, thus providing improved bleeding protection vs standard-acting FVIII products. AIM: To characterize the pharmacokinetic (PK) profile of BAY 94-9027 from phase 1, phase 2/3 (PROTECT VIII) and phase 3 (PROTECT VIII Kids) clinical trials in adults, adolescents and children with severe haemophilia A METHODS: Patients with severe haemophilia A (FVIII <1%) with >50 FVIII exposure days (EDs) and no history of inhibitors were included in the phase 1 (18-65 years, ≥150 EDs), PROTECT VIII (12-65 years, ≥150 EDs) and PROTECT VIII Kids (<12 years, >50 EDs) trials. PK parameters were assessed following a 25-IU/kg or 60-IU/kg BAY 94-9027 dose in the phase 1 study after the first and repeated infusion, in PROTECT VIII after the first and repeated 60-IU/kg infusion and in PROTECT VIII Kids after a single 60-IU/kg infusion. The chromogenic assay was used to assess FVIII activity. RESULTS: Compared with sucrose-formulated rFVIII, BAY 94-9027 had reduced clearance that resulted in a ~1.4-fold increase in half-life and dose-normalized area under the curve (AUC). The BAY 94-9027 PK profile was comparable after single- and repeated-dose administrations. Dose-proportional increases were observed between 25- and 60-IU/kg administrations. BAY 94-9027 PK characteristics were age dependent, consistent with other FVIII products. CONCLUSIONS: BAY 94-9027 shows an extended half-life and increased AUC vs standard-acting FVIII products. These PK characteristics will result in higher FVIII levels for longer duration.

Defining extended half-life rFVIII-A critical review of the evidence.

INTRODUCTION: Recent haemophilia treatment advances include new recombinant FVIII (rFVIII) products with improved pharmacokinetic (PK) properties that aim to reduce the burden of prophylaxis. These treatments are commonly referred to as extended half-life rFVIII products (EHL rFVIII). There is no uniform definition of what constitutes an EHL rFVIII. Such a definition would help physicians, patients and funders understand the properties of standard and EHL rFVIIIs and thus provide clarity when selecting an EHL in clinical settings. AIM: To critically assess the published evidence on new and emerging rFVIII products in order to propose a definition to classify EHL rFVIIIs. METHODS: We systematically searched PubMed, EMBASE and regulatory authorities (FDA/EMA/Health Canada) websites for publications and regulatory submissions describing prospective crossover PK studies evaluating rFVIIIs that demonstrate improved PK parameters in adults and adolescents with severe haemophilia A. RESULTS: Following critical analyses of the published data, we developed a holistic approach to defining rFVIIIs as EHLs, which requires all of the following: (i) using technology designed to extend rFVIII half-life; (ii) lacking bioequivalence with a standard rFVIII comparator-above the FDA/EMA cut-off of 125% for the 90% confidence intervals for area under the curve ratio; and (iii) having an extended half-life ratio measured in a PK comparator crossover study. CONCLUSION: In this systematic review, a pragmatic definition of EHL rFVIII has been proposed that should provide better clarity in clinical discussions surrounding the appropriate use of rFVIII products. At present, only products using PEGylation or Fc fusion half-life extension technology meet the proposed criteria for definition of EHL rFVIII.

Analysis of the Japanese subgroup in LEOPOLD II: a phase 2/3 study of BAY 81-8973, a new recombinant factor VIII product.

BAY 81-8973, a new full length recombinant FVIII product, has been developed for prophylaxis and on-demand therapy in patients with hemophilia A. LEOPOLD II was a phase 2/3 study comparing prophylaxis versus on-demand treatment with BAY 81-8973. The analysis herein evaluated the clinical profile in Japanese subjects enrolled in LEOPOLD II. The LEOPOLD II was an open-label randomized crossover study. Our analysis evaluated the efficacy using the annualized bleeding rate, safety, and pharmacokinetics in Japanese subjects with severe hemophilia A enrolled in LEOPOLD II. The median annualized bleeding rate was 59.9/year in the on-demand group and 1.9/year in the prophylaxis group for Japanese subjects. There were no study drug-related adverse events in the Japanese subjects. None of the subjects developed FVIII inhibitors. There were no apparent clinical differences in efficacy, safety, and pharmacokinetics between the Japanese and the non-Japanese subjects. Data for the Japanese subjects showed annualized bleeding rates to be remarkably lower in the prophylaxis group compared to the on-demand group and that BAY 81-8973 exhibited a good safety profile and tolerability. These results were similar for the non-Japanese subjects. The results support adoption of BAY 81-8973 for treatment of Japanese subjects with severe hemophilia A.

BAY 81-8973 (Octocog Alfa; Kovaltry®): A Review in Haemophilia A.

BAY 81-8973 (octocog alfa; Kovaltry®) is an unmodified, full-length, recombinant factor VIII (FVIII) concentrate with the same amino acid sequence as Kogenate® FS, but produced with innovative manufacturing technologies. This narrative review discusses the clinical efficacy and tolerability of BAY 81-8973 in haemophilia A, as well as summarizing its pharmacological properties. Results of the LEOPOLD I, LEOPOLD II and LEOPOLD Kids trials demonstrated that routine prophylaxis with intravenous BAY 81-8973 was associated with a low annualized bleeding rate (ABR) in previously treated adult and paediatric patients with severe haemophilia A. In terms of the ABR, BAY 81-8973 prophylaxis was more effective than on-demand treatment. Intravenous BAY 81-8973 was generally well tolerated, with no inhibitor development reported in previously treated patients in the completed LEOPOLD trial programme. In conclusion, BAY 81-8973 is a useful option for prophylaxis and treatment in adult and paediatric patients with haemophilia A.

Efficacy and safety of BAY 81-8973, a full-length recombinant factor VIII: results from the LEOPOLD I trial.

INTRODUCTION: BAY 81-8973 (Kovaltry(®) ) is a full-length, unmodified recombinant human factor VIII (FVIII) with the same amino acid sequence as sucrose-formulated recombinant FVIII and is produced using additional advanced manufacturing technologies. AIM: To demonstrate efficacy and safety of BAY 81-8973 for treatment of bleeds and as prophylaxis based on two different potency assignments. METHODS: In LEOPOLD I (ClinicalTrials.gov identifier, NCT01029340), males aged 12-65 years with severe haemophilia A and ≥150 exposure days received BAY 81-8973 20-50 IU kg(-1) two or three times per week for 12 months. Potency was based on chromogenic substrate assay per European Pharmacopoeia and label adjusted to mimic one-stage assay potency. Patients were randomized for potency sequence and crossed over potency groups after 6 months, followed by an optional 12-month extension. Primary efficacy endpoint was annualized bleeding rate (ABR). Patients also received BAY 81-8973 during major surgeries. RESULTS: Sixty-two patients received BAY 81-8973 prophylaxis and were included in the analysis. Median ABR was 1.0 (quartile 1, 0; quartile 3, 5.1) without clinically relevant differences between potency periods. Median ABR was similar for twice-weekly vs. three times-weekly dosing (1.0 vs. 2.0). Haemostasis was maintained during 12 major surgeries. Treatment-related adverse event (AE) incidence was ≤7% overall; no patient developed inhibitors. One patient with risk factors for cardiovascular disease developed a myocardial infarction. CONCLUSIONS: BAY 81-8973 was efficacious in preventing and treating bleeding episodes, irrespective of the potency assignment method, with few treatment-related AEs. Caution should be used when treating older patients with cardiovascular risk factors.

Safety and efficacy of BAY 81-8973 for surgery in previously treated patients with haemophilia A: results of the LEOPOLD clinical trial programme.

INTRODUCTION: BAY 81-8973 is a recombinant factor VIII (rFVIII) with the same amino acid sequence as Bayer's sucrose-formulated rFVIII (rFVIII-FS) but manufactured with certain more advanced technologies. AIM: To describe surgery outcomes with BAY 81-8973 in the LEOPOLD trials. METHODS: Male patients with severe haemophilia A and no inhibitors aged 12-65 years with ≥150 exposure days (EDs) to FVIII (LEOPOLD I and II), or aged ≤12 years with ≥50 EDs to FVIII (LEOPOLD Kids), received BAY 81-8973 based on dosing recommendations for rFVIII-FS according to surgical requirements. Haemostasis-related complications, investigator/surgeon assessment of haemostasis, blood loss, need for transfusion and use of BAY 81-8973 were determined. RESULTS: In LEOPOLD I and II, 11 patients (mean age, 35.3 years) underwent 13 major surgeries. In LEOPOLD Kids, one patient (aged 6 years) underwent one major surgery. Thirty-two adult and paediatric patients underwent 46 minor surgeries. Haemostasis was rated good or excellent in all major and minor surgeries. Blood loss during surgery did not exceed expected amounts; blood transfusions were required in three of the 14 major surgeries. For major surgeries in LEOPOLD I and II, patients received a presurgical 50-IU kg(-1) dose of BAY 81-8973; median nominal dose on day of surgery was 7000 IU (107.5 IU kg(-1) ). Total BAY 81-8973 dose was 2500 IU (108.7 IU kg(-1) ) on the day of the only major surgery in LEOPOLD Kids. No haemostasis-related complications were reported. CONCLUSIONS: Haemostatic control with BAY 81-8973 during all surgeries in the LEOPOLD trials was good or excellent, with no haemostasis-related complications.

BAY 81-8973 safety and efficacy for prophylaxis and treatment of bleeds in previously treated children with severe haemophilia A: results of the LEOPOLD Kids Trial.

INTRODUCTION: BAY 81-8973, a full-length, unmodified, recombinant factor VIII (FVIII) in development for treatment of haemophilia A, has the same primary amino acid sequence as Bayer's sucrose-formulated recombinant FVIII but is produced with more advanced manufacturing technologies. AIM: To demonstrate safety and efficacy of BAY 81-8973 for prophylaxis and treatment of bleeds in previously treated children. METHODS: In this phase III, multicentre, open-label, nonrandomized study, boys aged ≤12 years with severe haemophilia A and ≥50 exposure days (EDs) to FVIII products received prophylaxis with BAY 81-8973 25-50 IU kg(-1) ≥2 times weekly for ≥50 EDs. The efficacy endpoint was annualized number of total bleeds. Adverse events (AEs) and immunogenicity were assessed. RESULTS: Fifty-one patients were treated (age: <6 years, n = 25; 6-<12 years, n = 26) with a 2× per week (43%) or >2× per week (57%) regimen at study start. Median [quartile 1; quartile 3 (Q1; Q3)] annualized number of bleeds for the combined age groups was 1.90 (0; 6.02) for total bleeds, 0 (0; 2.01) for joint bleeds and 0 (0; 0) for spontaneous bleeds. Median (Q1; Q3) annualized number of total bleeds within 48 h of previous prophylaxis infusion was 1.88 (0; 3.97) for children aged <6 years and 0 (0; 1.96) for children aged 6-<12 years. No drug-related serious AEs or inhibitors were reported. CONCLUSIONS: Prophylaxis with BAY 81-8973 using individualized prophylaxis regimens of 2× per week, 3× per week and every-other-day infusions was efficacious in prevention and treatment of bleeds in children with severe haemophilia A. Treatment with BAY 81-8973 was well tolerated.

Foro de debate: seguridad de las alternativas a la transfusión alogénica en el paciente quirúrgico y/o crítico / Forum for debate: Safety of allogeneic blood transfusion alternatives in the surgical/critically ill patient

Estos últimos años han aparecido alertas de seguridad, no siempre bien sustentadas, que cuestionan el uso de algunas alternativas farmacológicas a la transfusión de sangre alogénica y/o lo restringen en indicaciones establecidas. Asistimos también a la preconización de otras alternativas, incluyendo productos hemáticos y fármacos antifibrinolíticos, sin que haya una base científica sólida que lo justifique. Por iniciativa del Grupo de Estudios Multidisciplinares sobre Autotransfusión y del Anemia Working Group España se reunió a un panel multidisciplinar de 23 expertos del área de cuidados de la salud en un foro de debate para: 1) analizar las diferentes alertas de seguridad en torno a ciertas alternativas a la transfusión; 2) estudiar los antecedentes que las han propiciado, la evidencia que las sustentan y las consecuencias que conllevan para la práctica clínica, y 3) emitir una valoración argumentada de la seguridad de cada alternativa a la transfusión cuestionada, según el uso clínico de la misma. Los integrantes del foro mantuvieron contactos por vía telemática y una reunión presencial en la que presentaron y discutieron las conclusiones sobre cada uno de los elementos examinados. Se elaboró un primer documento que fue sometido a 4 rondas de revisión y actualización hasta alcanzar un consenso, unánime en la mayoría de los casos. Presentamos la versión final del documento, aprobada por todos los miembros del panel, esperando sea de utilidad para nuestros colegas

In recent years, several safety alerts have questioned or restricted the use of some pharmacological alternatives to allogeneic blood transfusion in established indications. In contrast, there seems to be a promotion of other alternatives, based on blood products and/or antifibrinolytic drugs, which lack a solid scientific basis. The Multidisciplinary Autotransfusion Study Group and the Anemia Working Group España convened a multidisciplinary panel of 23 experts belonging to different healthcare areas in a forum for debate to: 1) analyze the different safety alerts referred to certain transfusion alternatives; 2) study the background leading to such alternatives, the evidence supporting them, and their consequences for everyday clinical practice, and 3) issue a weighted statement on the safety of each questioned transfusion alternative, according to its clinical use. The members of the forum maintained telematics contact for the exchange of information and the distribution of tasks, and a joint meeting was held where the conclusions on each of the items examined were presented and discussed. A first version of the document was drafted, and subjected to 4 rounds of review and updating until consensus was reached (unanimously in most cases). We present the final version of the document, approved by all panel members, and hope it will be useful for our colleagues

Half-life extended factor VIII for the treatment of hemophilia A.

Prophylactic infusion of factor VIII (FVIII) prevents joint bleeding and other hemorrhages in patients with hemophilia A. Conventional FVIII concentrates have a short half-life, with an average of about 12 h in adults, ranging in individual patients between 6 and 24 h, and even shorter in younger children. Therefore, effective prophylaxis requires frequent intravenous injection, usually three times per week or every other day. Several technologies are currently under investigation to extend the half-life of FVIII, including Fc fusion (Eloctate, Elocta, efmoroctocog alfa), addition of polyethylene glycol (turoctocog alfa pegol [N8-GP], BAY 94-9027, BAX 855), and a single-chain construct (CSL627). This review summarizes characteristics of products in clinical development and discusses their potential benefits.

Turoctocog alfa (NovoEight®)--from design to clinical proof of concept.

Turoctocog alfa (NovoEight®) is a recombinant factor VIII (rFVIII) with a truncated B-domain made from the sequence coding for 10 amino acids from the N-terminus and 11 amino acids from the C-terminus of the naturally occurring B-domain. Turoctocog alfa is produced in Chinese hamster ovary (CHO) cells without addition of any human- or animal-derived materials. During secretion, some rFVIII molecules are cleaved at the C-terminal of the heavy chain (HC) at amino acid 720, and a monoclonal antibody binding C-terminal to this position is used in the purification process allowing isolation of the intact rFVIII. Viral inactivation is ensured by a detergent inactivation step as well as a 20-nm nano-filtration step. Characterisation of the purified protein demonstrated that turoctocog alfa was fully sulphated at Tyr346 and Tyr1664, which is required for optimal proteolytic activation by thrombin. Kinetic assessments confirmed that turoctocog alfa was activated by thrombin at a similar rate as seen for other rFVIII products fully sulphated at these positions. Tyr1680 was also fully sulphated in turoctocog alfa resulting in strong affinity (low nm Kd ) for binding to von Willebrand factor (VWF). Half-lives of 7.2 ± 0.9 h in F8-KO mice and 8.9 ± 1.8 h haemophilia A dogs supported that turoctocog alfa bound to VWF after infusion. Functional studies including thromboelastography analysis of human haemophilia A whole blood with added turoctocog alfa and effect studies in mice bleeding models demonstrated a dose-dependent effect of turoctocog alfa. The non-clinical data thus confirm the haemostatic effect of turoctocog alfa and, together with the comprehensive clinical evaluation, support the use as FVIII replacement therapy in patients with haemophilia A.

PEGylated therapeutic proteins for haemophilia treatment: a review for haemophilia caregivers.

PEGylation is the technology involving the covalent attachment of polyethylene glycol (PEG) to a protein-, peptide- or small-molecule drug to improve their pharmacokinetic, pharmacodynamic and immunological profiles, and thus, enhance the therapeutic effect. Today, PEGylation of proteins is a well-established technology and is being used in the treatment of a variety of clinical disorders. Several PEGylated coagulation proteins for haemophilia A and B are under development with the goal of prolonging the circulation half-life of factor VIII (FVIII) or factor IX. The prolongation of half-life, resulting in less frequent injections can provide significant benefits in improving the quality of life of subjects with haemophilia and improvement in adherence to treatment. A review of published literature on PEGylated therapeutic products currently approved for human use and a discussion of a PEGylated recombinant FVIII molecule (BAY 94-9027, Bayer HealthCare, Berkeley, CA, USA) currently being investigated in the pivotal clinical trial prior to registration is provided. Available safety information of PEGylated proteins containing high molecular weight PEG does not indicate any safety concerns to date, following long-term (chronic) use in animal models or patients. Chronic use of currently available PEGylated products has been shown to be safe, paving the way for chronic use of PEGylated coagulation products in persons with haemophilia.

Pharmacokinetics and ex vivo whole blood clot formation of a new recombinant FVIII (N8) in haemophilia A dogs.

N8, a new recombinant factor VIII (rFVIII) compound developed for the treatment of haemophilia A, is produced in Chinese hamster ovary (CHO) cells and formulated without human- or animal-derived materials. The aim of the present study was to compare the pharmacokinetics (PK) and the procoagulant effect, measured by ex vivo whole blood clot formation, of N8 and a commercial rFVIII in a cross-over study in haemophilia A dogs. N8 and Advate® (100 IU kg⁻¹) were administered intravenously to three haemophilia A dogs. Blood was sampled between 0 and 120 h postdose and FVIII:C analysed. PK parameters maximum plasma concentration, area under the curve, half-life (t(½)), clearance, mean residence time (MRT) and volume of distribution and incremental recovery were calculated. Whole blood clotting time (WBCT) and thromboelastography (TEG®) were used to determine the haemostatic potential. No adverse reactions were observed with N8 or Advate ®. N8 and Advate® exhibited similar PK parameters, with t(½) 7.7-11 h and MRT 11-14 h. Both rFVIII compounds corrected the prolonged WBCT (> 48 min) to the range of normal dogs (8-12 min), i.e. N8 to 7.5-10.5 min and Advate® to 7.5-11.5 min. N8 and Advate® also normalized the whole blood clot formation according to TEG®. The native whole blood clotting assays (WBCT, TEG®) appeared to be more sensitive to low concentrations of FVIII than assays in citrated plasma samples. In conclusion, comparison of N8 and Advate ® in haemophilia A dogs revealed similar safety, similar PK and similar effects in whole blood clot formation assays.

Novel cryoprecipitate for wound healing and skin grafts in rats.

The authors sought to evaluate the ability of locally administered enhanced cryoprecipitate (eCryo) to improve the wound healing of split thickness skin grafts (STSG) and their donor sites. An STSG (5 x 5 cm) was harvested on the back of 30 rats and divided into four areas that were then treated in one of the following groups: A: 'standard' dressing without STSG; B: eCryo without STSG; C: eCryo with STSG coverage and D: STSG alone. Macroscopic and histological assessments (histomorphometric grading scale and cellular composition) were evaluated at days 7, 14, 21 and 28 for wound healing. All wound beds as well as STSGs healed well without any complications. Eighty per cent of the STSG showed a histological graft take of >75% after 28 days. There were no statistically significant differences of macroscopic or histological results between the groups at any time point. Preparation of eCryo is easy and effective. Its use as an adhesive for STSGs is safe and shows similar results as controls. The theoretical benefits of eCryo did not show significant differences. Possible reasons as well as important findings for future research on wound healing are discussed.

Safety and pharmacokinetics of a recombinant factor VIII with pegylated liposomes in severe hemophilia A.

BACKGROUND: BAY 79-4980 is a sucrose-formulated recombinant factor VIII (rFVIII-FS) combined with pegylated liposomes to prolong activity. OBJECTIVES: To investigate the safety, tolerability, bioavailability, pharmacokinetics and pharmacodynamics of a single administration of BAY 79-4980 compared with standard rFVIII-FS in patients with severe hemophilia A. METHODS: This randomized, double-blind study consisted of two crossover substudies comparing two doses of liposomal rFVIII-FS with standard rFVIII-FS. Males (12-60 years) with severe hemophilia A received a single infusion of standard rFVIII-FS (35 IU kg(-1)) followed by a single infusion of BAY 79-4980 (13 or 22 mg kg(-1) pegylated liposomes) or vice versa, with 12 observation days and a 2-day washout period between treatments. RESULTS: Twenty-six subjects were enrolled at two centers. No serious adverse events were reported. Transient increases in complement C3a, but not CH50, were seen in subjects receiving both the low- and high-liposome-dose BAY 79-4980. Mild transient elevations of total and low-density lipoprotein cholesterol were observed. There were no clinically significant differences in clotting or laboratory parameters or in pharmacokinetic behavior between BAY 79-4980 and standard rFVIII-FS. The number of subjects with spontaneous bleeds on days 1-14 postinfusion was low, and group comparisons were inconclusive. CONCLUSIONS: Single-dose administration of BAY 79-4980 is well tolerated in patients with severe hemophilia A. Plasma pharmacokinetics of FVIII cannot explain the extended protection from bleeding observed previously with BAY 79-4980. Further studies of efficacy and long-term safety of chronic administration are planned.

Liposomal approach towards the development of a longer-acting factor VIII.

Prevention of spontaneous bleeding in patients with severe haemophilia A usually requires therapeutic infusions every 2-3 days because of the short half-life of factor VIII (FVIII). Longer-acting FVIII products that require less frequent infusions would be beneficial and might obviate the need for central catheters in most patients. Liposomal formulation can enhance the efficacy of some therapeutic products. The incorporation of high-molecular weight polyethylene glycol (PEG) can extend the circulatory half-life of the liposome. These combined approaches led to the development of BAY 79-4,980, a PEG-containing liposomal version of Kogenate FS (rFVIII-FS). Results from preclinical models and early clinical trials have shown that BAY 79-4,980 prolongs the time to the next bleed. Further clinical evaluation of the efficacy and long-term safety of BAY 79-4,980 are planned.

Preclinical pharmacology of albumin-free B-domain deleted recombinant factor VIII.

A second-generation recombinant factor VIII molecule was developed with an albumin-free formulation. In this modified form of factor VIII, the N- and C-terminal sections of the B-domain are retained and fused at serine 743 and glutamine 1638, resulting in a B-domain deleted factor VIII protein known as ReFacto (Genetics Institute, Andover, MA). Preclinical studies of ReFacto have focused on efficacy of the product for the hemophilia A patient population. The efficacy and pharmacokinetic profiles of ReFacto were similar to plasma-derived factor VIII in correcting the hemostatic defect of hemophilia A dogs. Both ReFacto and plasma-derived human factor VIII (Octonativ-M7, Pharmacia, Stockholm, Sweden) were found to associate with von Willebrand factor (vWF) after infusion into hemophilia A dogs as demonstrated by size exclusion chromatography. Infusion of either ReFacto or Octonativ-M7 quickly corrected factor VIII coagulant activity (FVIIIc), whole blood clotting time (WBCT), and activated partial thromboplastin time (aPTT). No obvious differences were seen between ReFacto and Octonativ-M7. Both ReFacto and Octonativ-M7 treatment reduced secondary bleeding time to less than 6 minutes. The clearance was faster and the volume of distribution at steady state was larger for plasma-derived factor VIII compared with ReFacto. The half-life was similar between Octonativ-M7 and ReFacto. These data predict that ReFacto will be effective in correcting human factor VIII deficiency states.

Clinical evaluation of recombinant human factor VIII (BAY w 6240) in the treatment of hemophilia A.

A pilot clinical trial was conducted in five patients with severe hemophilia A to evaluate the safety and efficacy of a recombinant human factor VIII preparation, BAY w 6240 (rFVIII). In a comparative pharmacokinetic study of rFVIII and a plasma-derived factor VIII preparation (pdFVIII), the mean t1/2 values for rFVIII at week 1 and week 13 were 16.8 and 14.4 h, while this value for pdFVIII at week -2 was 16.9 h. There were no statistical differences between these values. The mean in vivo recovery rates of rFVIII were comparable to those of pdFVIII. When rFVIII was administered prophylactically three times a week for 4 weeks, no bleeding episodes were observed. Seventy-four bleeding episodes were assessed during the 6-month treatment period. The efficacy rate of the hemostatic effect was confirmed to be 95.9%. No adverse reactions attributable to rFVIII were observed in a total of 178 infusions. Neither FVIII-inhibitors nor antibodies to foreign proteins were detected. Vital signs and laboratory findings showed no significant changes attributable to rFVIII. These results suggest that rFVIII is safe and efficacious as replacement therapy for hemophilia A.