Eradication of FIX inhibitor in haemophilia B children using low-dose immune tolerance induction with rituximab-based immunosuppressive agent(s) in China.

INTRODUCTION: Development of haemophilia B inhibitors (HBI) results in the ineffectiveness of FIX replacement therapy. Inhibitor eradication by immune tolerance induction (ITI) is therefore necessary. In HBI, ITI even at high FIX dose is less effective and has a higher risk of severe complications. AIM: To characterize clinical features and outcome of ITI on HBI. METHODS: This retrospective study was conducted in Haemophilia Paediatric Comprehensive Care Centre of China. We used low-dose ITI (25-50 FIX IU/kg/three-times-weekly to every-other-day) with domestic prothrombin complex concentrate (PCC), combined with two successive immunosuppressive (IS) regimens. RESULTS: Sixteen HBI children, representing 5.7% of all and 14.4% of our severe registered HB patients, were enroled. Seven cases reported allergic reactions (ARs) proximal to inhibitor development. The historic peak inhibitor titre was median 54.2 (range 4.7-512) BU, and 15 (93.8%) had high-titre inhibitors. Twelve patients adherent to ITI were analysable. Of the nine ITI patients who received rituximab/prednisone (IS Regimen-1), four achieved tolerization in 1.4-43.3 months. Two subsequently relapsed but re-tolerized after a second course of IS Regimen-1. During ITI, the median treated bleed was .39/month (82.7% reduction from before ITI), and the incidence of AR and nephrotic syndrome (NS) complications was each at 22% (2/9). Three ITI patients received modified 'Beutel' protocol (IS Regimen-2) using multiple-IS-drugs, and two had rapid tolerization (.8 and 1.8 months). CONCLUSIONS: Inhibitor eradication could be achieved by low-dose ITI protocol using PCC combined with IS. Larger studies are needed to confirm if ITI with IS Regimen-2 is more effective with less complications.

Bone mineral density in haemophilia - a multicentre study evaluating the impact of different replacement regimens.

AIM: The aim of this study was to investigate if prophylactic treatment in severe haemophilia impact on bone mineral densisty (BMD) in adults with haemophilia A/B. METHODS: Subjects with haemophilia (n = 120) underwent bone-density measurement and clinical data was collected. BMD in subjects with severe haemophilia on high-dose prophylaxis (n = 41) was compared to BMD in subjects with mild haemophilia (n = 33) and to severe haemophilia treated with intermediate-dose prophylaxis (n = 32) or on-demand replacement therapy (n = 14). RESULTS: Subjects with severe haemophilia on high-dose prophylaxis showed BMD at total hip comparable to subjects with mild haemophilia (median BMD 955.8 and 977.4 mg/cm2 (P = .17), respectively). No difference in BMD was found related to type of prophylactic regimen (median BMD 955.8 and 942.4 mg/cm2 , in high-dose and intermediate dose groups, respectively; P = .70). Subjects with severe disease treated on-demand had significantly lower BMD compared to subjects on a high-dose prophylactic regimen (median BMD 771.8 and 955.8 mg/cm2 (P = .001), respectively). BMD decreased significantly with age, regardless of severity of haemophilia disease. In a multivariate analysis, adjusted for disease status and age, type of prophylactic regimen was not significantly associated with osteoporosis development. CONCLUSION: We show that BMD differs in persons with severe haemophilia on propylaxis as compared to those treated on-demand, but that type of prophylactic regimen does not reflect on BMD. The difference between treatment groups was mainly explained by an age difference between groups. However, patients on prophylaxis displayed a high degree of normal BMD not far from mild haemophilia at comparative age.

Nonfactor Therapies: New Approaches to Prophylactic Treatment of Haemophilia.

For several decades, the treatment of haemophilia has relied on factor replacement therapy, which restores haemostasis by replacing the missing coagulation factor. In recent years, novel alternative therapies for the treatment of haemophilia in patients with and without inhibitors have been developed. These emergent therapies promote haemostasis by mimicking coagulation factors or inhibiting natural anticoagulants. They provide a less invasive route of administration (i.e. subcutaneous) and some offer reduced frequency of dosing (i.e. every 2 weeks, monthly) compared with the majority of factor replacement therapies, and thus have the potential to simplify treatment, increase adherence and subsequently improve outcomes for patients. Their introduction has transformed the care of haemophilia patients with inhibitors to factor VIII, with similar expectation for haemophilia B patients with inhibitors. However, these therapies also come with several new challenges including their limitation to prophylactic treatment, the observed increased incidence of thrombosis, or their impact on the natural history of the disease and potential disruption of existing treatment guidelines like the use of immune tolerance induction. Moreover, questions remain regarding the long-term impact of non-replacement therapies on joint health as well as the optimal strategy to manage breakthrough bleeds in patients with inhibitors.

Preclinical evaluation of a next-generation, subcutaneously administered, coagulation factor IX variant, dalcinonacog alfa.

INTRODUCTION: The rapid clearance of factor IX necessitates frequent intravenous administrations to achieve effective prophylaxis for patients with hemophilia B. Subcutaneous administration has historically been limited by low bioavailability and potency. Dalcinonacog alfa was developed using a rational design approach to be a subcutaneously administered, next-generation coagulation prophylactic factor IX therapy. AIM: This study aimed to investigate the pharmacokinetic, pharmacodynamic, and safety profile of dalcinonacog alfa administered subcutaneously in hemophilia B dogs. METHODS: Two hemophilia B dogs received single-dose daily subcutaneous dalcinonacog alfa injections for six days. Factor IX antigen and activity, whole blood clotting time, and activated partial thromboplastin time were measured at various time points. Additionally, safety assessments for clinical adverse events and evaluations of laboratory test results were conducted. RESULTS: There was an increase in plasma factor IX antigen with daily subcutaneous dalcinonacog alfa. Bioavailability of subcutaneous dalcinonacog alfa was 10.3% in hemophilia B dogs. Daily subcutaneous dosing of dalcinonacog alfa demonstrated the effects of bioavailability, time to maximal concentration, and half-life by reaching a steady-state activity sufficient to correct severe hemophilia to normal, after four days. CONCLUSION: The increased potency of dalcinonacog alfa facilitated the initiation and completion of the Phase 1/2 subcutaneous dosing study in individuals with hemophilia B.

Alternative treatment options for pediatric hemophilia B patients with high-responding inhibitors: A thrombin generation-guided study.

Little is known about the challenging treatment of pediatric patients with hemophilia B and inhibitors due to disease rarity. We describe three patients diagnosed in childhood and followed up to 9 years. All three had allergic reactions to Factor IX, but two were later safely treated for bleeding episodes with activated prothrombin complex concentrates (APCC = FEIBA). The third was given only recombinant activated Factor VIIa. Based on ex vivo thrombin generation analysis, a new alternative treatment of combined bypassing agents was administered for bleeding episodes and several minor surgical procedures with no treatment-associated adverse events or thrombosis.

Iranian Low-dose Escalating Prophylaxis Regimen in Children with Severe Hemophilia A and B.

Establishing an appropriate prophylaxis regimen for children with hemophilia is a critical challenge in developing countries. Barriers including availability and affordability, catheter-related complications, and inhibitor development risks have led to the introduction of new tailored prophylaxis regimens in different countries. This study emphasizes on the benefits of the Iranian low-dose escalating prophylaxis regimen in a Hemophilia Comprehensive Care Center in Iran. Referred patients with hemophilia less than 15 years of age, who were subject to prophylaxis regimen, are studied retrospectively. A once-weekly prophylaxis regimen of 25 IU/kg was started for the patients primarily. Their prophylaxis regimen was changed to 25 IU/kg twice a week and then 3 times a week when they experienced 3 joint bleedings, 4 soft tissue bleedings, or a 1 life-threatening bleed without a specific trauma history. Overall, 25 patients with severe hemophilia and at least 6-month history of on-demand (OD) treatment were studied. A mean of 1754 IU/kg/yr of coagulation factors, used for OD and prophylaxis purposes, was sufficient to decrease the mean annual bleeding rate (ABR) to 1.86 after prophylaxis. It also reduced the mean hospitalization days and the mean number of target joints to 0.24 and 0.16, respectively. Overall, 19 (76%) patients were continuing their once-weekly regimen at the end of the follow-up. None of the patients needed 3-times-a-week regimen or central venous catheterization and none developed inhibitors in the follow-up. Benefits of the Iranian low-dose escalating prophylaxis regimen prove equal to some of the previous 3-times-a-week prophylaxis regimens in reducing the ABR and hospitalizations.

Bypassing agent prophylaxis in people with hemophilia A or B with inhibitors.

BACKGROUND: People with hemophilia A or B with inhibitors are at high risk of bleeding complications. Infusion of bypassing agents, such as recombinant activated FVII (rFVIIa) and plasma-derived activated prothrombin complex concentrate, are suggested as alternative therapies to factor VIII (haemophilia A) or IX (haemophilia B) for individuals who no longer respond to these treatments because they develop inhibitory antibodies. The ultimate goal of treatment is to preserve the individual's joints, otherwise destroyed by recurrent bleeds. OBJECTIVES: To assess the effects of bypassing agent prophylaxis to prevent bleeding in people with hemophilia A or B and inhibitors. SEARCH METHODS: We searched for relevant studies from the Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched trial registries (16 February 2017) and bibliographic references of retrieved studies were reviewed for potential articles to be included in the review.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Coagulopathies Trials Register: 12 December 2016. SELECTION CRITERIA: We included randomized and quasi-randomized controlled studies (cross-over or parallel design) evaluating the effect of prophylaxis treatment with bypassing agents compared with on-demand treatment, or studies evaluating the effects of high-dose compared with low-dose prophylaxis in males of any age with hemophilia with inhibitors. DATA COLLECTION AND ANALYSIS: Two authors independently selected studies and extracted data and assessed the risk of bias according to standard Cochrane criteria. They assessed the quality of the evidence using the GRADE criteria. MAIN RESULTS: We included four randomized studies (duration 7 to 15 months) involving 116 males. Risk of bias was judged to be high in two studies due to the open-label study design and in one study due to attrition bias.Two studies compared on-demand treatment to prophylaxis with bypassing agents. In one study (34 males) prophylaxis significantly reduced mean overall bleeding rates, MD - 7.27 (95% CI -9.92 to -4.62) (low quality evidence), mean number of overall bleeding events per month, MD -1.10 (95% CI -1.54 to -0.66), mean number of hemarthrosis, MD -6.60 (95% CI -9.32 to -3.88) (low quality evidence) and mean number of joints that had hemarthrosis, MD -0.90 (95% CI -1.36 to -0.44). The meta-analysis did not conclusively demonstrate significant benefit of prophylaxis on health-related quality of life as measured by Haem-A-QoL score, EQ-5D total score and utility score, EQ-5D VAS and SF-36 physical summary and mental summary score (low quality evidence for all health-related quality of life analyses).The remaining two studies compared dose regimens. The results from one study (22 males) did not conclusively demonstrate benefit or harm of high-dose versus low-dose recombinant activated factor VIIa (rFVIIa) as a prophylaxis for overall bleeding rate, MD -0.82 (95% CI -2.27 to 0.63) (moderate quality evidence), target joint bleeding rate, MD -3.20 (95% CI -7.23 to 0.83) (moderate quality evidence) and serious adverse events, RR 9.00 (95% CI, 0.54 to 149.50) (moderate quality evidence).The overall quality of evidence was moderate to low due to imprecision from limited information provided by studies with small sample sizes and incomplete outcome data in one study. AUTHORS' CONCLUSIONS: The evidence suggests that prophylaxis with bypassing agents may be effective in reducing bleeding in males with hemophilia with inhibitors. However, there is a lack of evidence for the superiority of one agent over the other or for the optimum dosage regimen. Further studies are needed to evaluate the benefits and harms of prophylaxis treatment on health-related quality of life, as well as the effects of dose of bypassing agents on the outcomes.

Heparin supplement counteracts the prohemostatic effect of prothrombin complex concentrate and factor IX concentrate: An in vitro evaluation.

INTRODUCTION: Coagulation factor concentrates like factor IX (FIX) and prothrombin complex concentrate (PCC) can contain anticoagulant substances that may hamper their procoagulant effectiveness in the treatment of hemophilia B or reversal of oral anticoagulation, as well as the laboratory assessment thereof. The aim of the present study was to evaluate the influence of anticoagulant heparin supplement on the prohemostatic potential of different PCCs and FIX concentrates. MATERIALS AND METHODS: Prohemostatic potential was evaluated in vitro employing PT/aPTT, thrombography (TGA) and thromboelastography (TEG) with FIX deficient plasma, vitamin K antagonist (VKA)-anticoagulated plasma and plasma anticoagulated with rivaroxaban. RESULTS: Most PCCs contained heparin, while heparin was detected in 1 out of 4 examined FIX concentrates. All heparin-containing clotting factor concentrates showed severely hampered prohemostatic effects when therapeutic doses were added to anticoagulated plasmas. Upon heparin removal, comparable prohemostatic effects were observed. Of importance is the notion that the anticoagulant effect of heparin was enhanced by rivaroxaban, resulting in a 7 fold increased PT sensitivity towards heparin in the presence of 500µg/L rivaroxaban. CONCLUSIONS: Compositional differences between clotting factor concentrates should be taken into account. Therapeutic levels of heparin may be co-infused when treating emergency bleeds with high prohemostatic drug doses, particularly those recommended in the reversal of non-VKA anticoagulants such as rivaroxaban by PCC. Given the relative short half-life of heparin compared to vitamin K-dependent clotting factors, an anticoagulant heparin effect shortly after concentrate infusion should be considered clinically and while interpreting laboratory coagulation parameters.

Preclinical safety and efficacy of a new recombinant FIX drug product for treatment of hemophilia B.

Baxter has developed a new recombinant factor IX (rFIX) drug product (BAX326) for treating patients with hemophilia B, or congenital FIX deficiency. An extensive preclinical program evaluated the pharmacokinetics, efficacy, and safety of BAX326 in different species. The efficacy of BAX326 was tested in three mouse models of primary pharmacodynamics: tail-tip bleeding, carotid occlusion, and thrombelastography. The pharmacokinetics was evaluated after a single intravenous bolus injection in mice, rats, and macaques. Toxicity was assessed in rats and macaques, safety pharmacology in rabbits and macaques, and immunogenicity in mice. BAX326 was shown to be efficacious in all three primary pharmacodynamic studies (P ≤ 0.0076). Hemostatic efficacy was dose related and similar for the three lots tested. Pharmacokinetic results showed that rFIX activity and rFIX antigen concentrations declined in a bi-phasic manner, similar to a previously licensed rFIX product. BAX326 was well tolerated in rabbits and macaques at all dose levels; no thrombogenic events and no adverse clinical, respiratory, or cardiovascular effects occurred. BAX326 was also shown to have a similar immunogenicity profile to the comparator rFIX product in mice. These results demonstrate that BAX326 has a favorable preclinical safety and efficacy profile, predictive of a comparable effect to that of the previously licensed rFIX in humans.

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.

Prolonged activity of factor IX as a monomeric Fc fusion protein.

Treatment of hemophilia B requires frequent infusions of factor IX (FIX) to prophylax against bleeding episodes. Hemophilia B management would benefit from a FIX protein with an extended half-life. A recombinant fusion protein (rFIXFc) containing a single FIX molecule attached to the Fc region of immunoglobulin G was administered intravenously and found to have an extended half-life, compared with recombinant FIX (rFIX) in normal mice, rats, monkeys, and FIX-deficient mice and dogs. Recombinant FIXFc protein concentration was determined in all species, and rFIXFc activity was measured in FIX-deficient animals. The half-life of rFIXFc was approximately 3- to 4-fold longer than that of rFIX in all species. In contrast, in mice in which the neonatal Fc receptor (FcRn) was deleted, the half-life of rFIXFc was similar to rFIX, confirming the increased circulatory time was due to protection of the rFIXFc via the Fc/FcRn interaction. Whole blood clotting time in FIX-deficient mice was corrected through 144 hours for rFIXFc, compared with 72 hours for rFIX; similar results were observed in FIX-deficient dogs. Taken together, these studies show the enhanced pharmacodynamic and pharmacokinetic properties of the rFIXFc fusion protein and provide the basis for evaluating rFIXFc in patients with hemophilia B.

Prevalence and risk factors associated with decreased bone mineral density in patients with haemophilia.

Osteoporosis in adult males is an under-recognized problem. Patients with haemophilia have several predisposing factors for developing decreased bone mineral density (BMD) including prolonged periods of immobility, reduced weight bearing and co-morbidities associated with bone loss. To establish prevalence and risk factors associated with decreased BMD in patients with haemophilia. Adults with moderate or severe haemophilia A or B underwent dual-energy X-ray absorptiometry (DXA). BMD was correlated to laboratory values, joint mobility measurements and physical activity questionnaires. Thirty patients completed evaluations. The median age was 41.5 years (range 18-61). Median lowest T-score by DXA was -1.7 (range: -5.8 to +0.6), with the femoral neck being the site of the lowest T-scores. Based on World Health Organization criteria, 70% of patients had decreased BMD. Twenty-seven per cent of the participants (n = 8) had osteoporosis and 43% (n = 13) had osteopenia. Variables associated with increased bone loss included lower serum 25-hydroxyvitamin D levels (P = 0.03), lower body mass index (P = 0.047), lower activity scores (P = 0.02), decreased joint range of motion (P = 0.046), HIV (P = 0.03), HCV (P = 0.02), history of inhibitor (P = 0.01) and age (P = 0.03). Adults with haemophilia are at increased risk for developing osteoporosis. A history of HCV and HIV infections, decreased joint range-of-motion, decreased activity levels, history of an inhibitor and low body weight predict bone loss and suggest a population to target for screening. A high prevalence of vitamin D insufficiency was observed. Future studies should investigate interventions, including vitamin D supplementation, to prevent bone loss and fractures for this at-risk population.

Current European practice in immune tolerance induction therapy in patients with haemophilia and inhibitors.

The management of patients with inhibitors is an important challenge in haemophilia care. The lack of randomized controlled trials means that clinical decisions are generally based on subjective opinions, and purchasers' attention is likely to focus on the costs of treatment. In order to assess the current management of inhibitor patients and use of immune tolerance induction therapy (ITI) in Europe, we performed a survey within a European network of 21 comprehensive care centres from 14 countries (the European Haemophilia Therapy Standardisation Board). The survey identified a total of 381 patients with inhibitors attending the centres, 211 (55.4%) of whom had never been exposed to ITI. Between 1998 and 2003, the centres performed 233 procedures and 114 (48.9%) were successful. The survey demonstrated that dosing, which is the time to start and stop the ITI, the type of concentrate to use and the definition of success varied among the centres. Well-designed trials are warranted to guide decision-making, but in the absence of these studies we have developed consensus guidance for the management of inhibitor patients based on current clinical practice, as identified by the survey, and review of the literature.

Human coagulation factor FVIIa (recombinant) in the management of limb-threatening bleeds unresponsive to alternative therapies: results from the NovoSeven emergency-use programme in patients with severe haemophilia or with acquired inhibitors.

This open-label, emergency-use study evaluated the efficacy and safety of activated human coagulation factor VIIa (recombinant) (rFVIIa) (NovoSeven; Novo Nordisk Pharmaceuticals, Inc., New Jersey, USA) in treating limb-threatening joint or muscle bleeds in 17 patients with haemophilia A or B and six patients with acquired inhibitors to factor VIII or factor IX. All patients had previously failed on one or more alternative therapies. rFVIIa administration was effective or partially effective in controlling joint or muscle bleeds in 34 out of 35 (97%) bleeding episodes; in 23 patients, 14 of 17 (82%) muscle bleeds and 16 of 18 (89%) joint bleeds were effectively controlled. These findings suggest that rFVIIa is an effective and well-tolerated therapeutic option in the management of joint or muscle haemorrhage in patients with haemophilia and in patients with acquired inhibitors.

Activated recombinant human coagulation factor VII (rFVIIa) therapy for abdominal bleeding in patients with inhibitory antibodies to factor VIII.

Eight patients with inhibitors to factor VIII (4 hemophilia A and 4 nonhemophilic) were treated with recombinant activated factor VII (rFVIIa) to control severe abdominal bleeding. The recombinant factor was supplied under an open-label, emergency-use program to patients previously unresponsive to one or more alternative therapies. Therapy with rFVIIa was administered for nine separate bleeding events; one patient was treated for two separate bleeding episodes. Patients were treated for an average of 9 days and received a mean total dose of 5.2 mg of rFVIIa for control of bleeding. Treatment was considered successful and hemostasis adequate in 7 of the 9 episodes (78%). Treatment with rFVIIa was partially successful in one other episode. Four patients in this series experienced serious adverse events; all the adverse events were considered unrelated to rFVIIa therapy. The results of this limited series indicate that rFVIIa is an effective means of managing life-threatening abdominal bleeding in individuals with hemophilia or acquired antibodies to factor VIII.

Recombinant factor VIIa for patients with inhibitors to factor VIII or IX or factor VII deficiency.

Inhibitors to factor VIII (FVIII) or IX (FIX) in patients with haemophilia A or B create a challenging problem for the treatment of these patients. Recombinant FVIIa (rFVIIa; NovoSeven, Novo Nordisk A/S, Bagsvaerd, Denmark) is a realistic treatment option, owing to its specific mode of action and lack of immunogenicity. This was a multicentre, open-label, compassionate-use trial in patients with severe haemophilia A (FVIII:C < 1%) or B (FIX:C < 1%) with inhibitors, acquired antibodies to FVIII or FIX, or FVII deficiency (FVII:C < 5%), for whom alternative therapies had failed or were contraindicated. Patients received rFVIIa treatment for life- or limb-threatening bleeding episodes or for coverage during essential surgery. The mean rFVIIa dose was approximately 90 microg kg-1 for haemophilia A/B and acquired inhibitor patients, and 25 microg kg-1 for FVII-deficient patients. Efficacy data for 67 treatment episodes (45 bleeding episodes, 22 surgical procedures) are presented; seven patients were treated for a concurrent serious bleeding episode and surgical procedure. At the end of treatment, rFVIIa was effective or partially effective in 85% of serious bleeding episodes. During surgery, bleeding was assessed as none or less than or equivalent to normal in 91% of surgical procedures; postoperatively, 91% of procedures were associated with no or minimal oozing. During 60 separate treatment episodes, 26 adverse events (22 nonserious, four serious) were reported in 15 patients, during 17 bleeding episodes or surgical procedures. Only 10 were considered as having a possible, probable, or unknown relationship with rFVIIa; of these, fever (n=2) and thrombophlebitis (n=3) were the most common. There was no evidence of disseminated intravascular coagulation. In conclusion, rFVIIa is an effective, well-tolerated treatment for serious bleeding episodes and bleeding associated with surgical procedures in patients with severe haemophilia A/B with inhibitors, acquired inhibitors, or FVII deficiency.

Preclinical studies of recombinant factor IX.

Recombinant factor IX (rFIX) has been extensively evaluated in preclinical studies. Dog model study of hemophilia B indicated that rFIX was as effective as a highly purified plasma-derived replacement factor in normalizing indices of hemostasis. Pharmacokinetic studies indicated a dose-proportional profile for rFIX. Pharmacokinetic/pharmacodynamic analysis showed that increases in the plasma concentration of rFIX following administration were closely correlated with measured factor IX activity in the plasma. Appropriate in vitro and in vivo toxicology studies have been performed to support the clinical use of rFIX for the treatment of hemophilia B. Finally, experiments in a model of thrombogenicity indicated that in animals rFIX has a low thrombogenic potential. The preclinical results provided a basis for proceeding with human clinical trials.

Recombinant factor IX.

Despite the introduction of recombinant preparations of factor VIII and recombinant factor VII and VIIa, patients with other forms of hemophilia, especially hemophilia B, have remained at increased risk for blood borne viruses because of a lack of clinically utilizable preparations of recombinant factor IX. This report describes the state of current tests with a recently licensed preparation of recombinant factor IX, BeneFix, from Genetics Institute. Structurally, functionally, and therapeutically, recombinant factor IX is comparable to monoclonal plasma-derived factor IX. The only observed difference between recombinant and plasma factor IX is the recovery in pharmacokinetic studies where recombinant factor IX recovery was approximately 72% that of a plasma factor IX product. This difference is attributed to be due to minor differences in the post-translational modification of recombinant factor IX compared to plasma. These studies demonstrate that recombinant factor IX is effective in the treatment of hemophilia B and has the safety profile expected from a product prepared by recombinant technology.

[Clinical experience of urological surgery of the patients with hemostatic disorder or hemolytic disease].

This report deals with clinical experience of urologic surgery of patients with hemostatic disorder or hemolytic disease. In the past 5 years from May 1986, 14 operations were conducted in our clinic on 13 patients, consisting of 4 with von Willebrand disease (vWd), 1 with hemophilia B, 4 who had warfarin administration, 3 with essential thrombocythemia and 2 with spherocytosis. Almost all patients were treated hematologically before the urological operations. Except in 1 case, the post-operative course was favorable and under hematologic control. Massive bleeding in 1 case was obviously attributable to over-dosage of warfarin. It is difficult to determine the optimal dose of warfarin under an unstable hemostatic condition during the operation and recovery periods. However, it is possible to carry out urologic surgery for these patients under appropriate hematologic control, and ESWL was safely performed without medical treatment on 3 patients; 1 with vWd, 1 treated with warfarin and 1 with spherocytosis.