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PubMed2001

Recombinant factor IX (BeneFix) by adjusted continuous infusion: a study of stability, sterility and clinical experience.

The safety and efficacy of adjusted continuous infusion (CI) of recombinant factor IX (FIX; BeneFix) was assessed in vitro and in a clinical study. BeneFix was reconstituted at 100 IU mL-1 with or without unfractionated heparin (4 U mL-1) and stored at either 4 degrees C or room temperature. Reconstituted BeneFix retained at least 90% activity over 14 days if stored at 4 degrees C but stability was reduced at room temperature. BeneFix reconstituted in a sterile pharmacy was free of bacterial contamination. Six patients with haemophilia B received seven CIs of BeneFix to cover routine surgery and severe bleeding episodes. The CIs lasted between 3 and 10 days. In all cases, haemostasis was excellent and the desired therapeutic FIX level was easily maintained. No thrombotic episodes or inhibitor development occurred but two patients developed thrombophlebitis at the infusion site when heparin was not added to the infusion. BeneFix is not currently licensed for CI and we suggest that studies to enable licensing should be established as soon as possible.

Blood Loss, Surgical↗
PubMed2000

Factor IX mutations in South Africans and African Americans are compatible with primarily endogenous influences upon recent germline mutations.

Similar patterns of germline mutations in the factor IX gene (F9) have been observed in certain geographically and racially diverse populations. Germline mutation data have not been available from any region of Africa or from the Black race. Analysis of mutation data for Blacks is of interest, since this race has a high frequency of polymorphism compared to other races. This high frequency has been interpreted as evidence for the "out of Africa" hypothesis for the origin of humans, but it is possible that Blacks have a higher mutation rate due to genetic differences or environmental exposures. We report 26 independent mutations that were detected in patients of mixed races with hemophilia B from South Africa. The pattern of mutation in patients from this African country was similar to that of U.S. Caucasians. In addition, 22 independent mutation were detected in African American patients. The patterns of independent germline mutation in 22 African Americans (and in a combination 34 North American and African Blacks) is similar to that of U.S. Caucasians. Neither genetic differences between the Black and Caucasian races nor environmental and cultural differences between South Africa and the U.S. alter the germline pattern of mutation observed in F9. Hum Mutat 16:372, 2000.

Black People↗
PubMed2004

Effects of genetic fusion of factor IX to albumin on in vivo clearance in mice and rabbits.

Individuals with haemophilia B require replacement therapy with recombinant or plasma-derived coagulation factor IX (fIX). More benefit per injected dose might be obtained if fIX clearance could be slowed. The contribution of overall size to fIX clearance was explored, using genetic fusion to albumin. Recombinant murine fIX (MIX), and three proteins with C-terminal epitope tags were expressed in HEK 293 cells: tagged MIX (MIXT), tagged mouse serum albumin (MSAT) and MFUST, in which MIX and MSAT were fused in a single polypeptide chain. Proteins MFUST and MIXT were two- to threefold less active in clotting assays than MIX. In mice, the area under the clearance curve (AUC) was reduced for MFUST compared with MSAT or plasma-derived MSA (pd-MSA); the terminal catabolic half-life (t(0.5)) did not differ amongst the three proteins. Two minutes after injection, >40% of the injected MFUST was found in the liver, compared with <10% of either MSAT or pd-MSA. In rabbits, the AUC for MFUST was reduced compared to MIXT, MSAT, or pd-MSA, while the t(0.5) of the fusion protein fell between that of MIXT and MSAT or pd-MSA. Similar results were obtained with non-radioactive fused or non-fused recombinant human fIX in fIX knockout mice. The clearance behaviour of the fusion protein thus more closely resembled that of fIX than that of albumin despite a modest increase in terminal half-life, suggesting that fIX-specific interactions that are important in determining clearance were maintained in spite of the increased size of the fusion protein.

Animals↗
PubMed1987

MspI polymorphic site within the factor IX gene. Localization of the site and an improved method for detection.

We have localized the position of the MspI polymorphic site that exists within the factor IX gene. The location of the MspI polymorphic site is within intron D, 1.9 kb upstream from the beginning of exon V and 4 kb downstream from a known polymorphic TaqI site. The use of a specific genomic probe simplifies the interpretation of the MspI polymorphism by reducing the number of non-overlaping DNA fragments to three bands; 2.4, 3.4, and 5.8 kb.

Chromosome Mapping↗
PubMed1990

Factor IX concentrate versus prothrombin complex concentrate for the treatment of hemophilia B during surgery.

Hemophilia B patients are usually treated for the prevention and control of bleeding episodes with a plasma derivative containing the four vitamin K-dependent clotting factors (PPSB). Prothrombin complex concentrate and the French PPSB concentrate are known to be thrombogenic when used in long-term treatment of surgical patients. The present study reports two cases of thrombotic episodes following surgery in PPSB-treated hemophilia B patients. Since 1986, there has been available a factor IX (FIX) concentrate depleted of the other vitamin K-dependent clotting factors and virally inactivated by the solvent-detergent method. This preparation has been used as replacement therapy in six patients with severe hemophilia B who were to undergo orthopedic surgery. The management of the patients before and after operation was without any thrombotic complication or undesirable side effects. The present study suggests that there is a need for an FIX preparation devoid of the other vitamin K-dependent clotting factors for long-term therapy of hemophilia B patients.

Adult↗
PubMed2002

AAV-mediated factor IX gene transfer to skeletal muscle in patients with severe hemophilia B.

Hemophilia B is an X-linked coagulopathy caused by absence of functional coagulation factor IX (F.IX). Previously, we established an experimental basis for gene transfer as a method of treating the disease in mice and hemophilic dogs through intramuscular injection of a recombinant adeno-associated viral (rAAV) vector expressing F.IX. In this study we investigated the safety of this approach in patients with hemophilia B. In an open-label dose-escalation study, adult men with severe hemophilia B (F.IX < 1%) due to a missense mutation were injected at multiple intramuscular sites with an rAAV vector. At doses ranging from 2 x 10(11) vector genomes (vg)/kg to 1.8 x 10(12) vg/kg, there was no evidence of local or systemic toxicity up to 40 months after injection. Muscle biopsies of injection sites performed 2 to 10 months after vector administration confirmed gene transfer as evidenced by Southern blot and transgene expression as evidenced by immunohistochemical staining. Pre-existing high-titer antibodies to AAV did not prevent gene transfer or expression. Despite strong evidence for gene transfer and expression, circulating levels of F.IX were in all cases less than 2% and most were less than 1%. Although more extensive transduction of muscle fibers will be required to develop a therapy that reliably raises circulating levels to more than 1% in all subjects, these results of the first parenteral administration of rAAV demonstrate that administration of AAV vector by the intramuscular route is safe at the doses tested and effects gene transfer and expression in humans in a manner similar to that seen in animals.

Adult↗
PubMed1988

The Malmö polymorphism of coagulation factor IX, an immunologic polymorphism due to dimorphism of residue 148 that is in linkage disequilibrium with two other F.IX polymorphisms.

A mouse monoclonal antibody (MAB 9.9) to coagulation factor IX (F.IX) detects a polymorphism in the plasma of normal people. Its epitope has been narrowed down to less than 6 amino acids in the activation peptide of the X-linked F.IX protein. The activation peptide contains a dimorphism--Thr:Ala--at position 148 of the protein. Using synthetic oligonucleotides, we have demonstrated that (1) the F.IX which reacts with 9.9 has Thr at position 148 and (2) that which does not has Ala. Positive reactors (148thr) are designated Malmö A, and negative reactors (148ala) are designated Malmö B. The plasma levels of AA women are indistinguishable from those of A men, and both B men and BB women are null against MAB 9.9. The plasma level of Malmö A in AB women is approximately half that of AA women, and "lyonization" is clearly operating in the heterozygotes. The dimorphism is in strong linkage disequilibrium with two other intragenic RFLPs, TaqI and XmnI. Furthermore, intragenic crossing-over--including double crossing-over--appears to have occurred between the three sites. Seven of the eight possible haplotypes have been identified, five in men and two others in women. The immunoassay that identifies approximately 50% of the AB women in the pool of Malmö A females with 95% confidence identifies men unambiguously as A or B. The assay would be very useful for population-genetic studies of the Malmö epitope if the studies were limited to men.

Antibodies, Monoclonal↗
PubMed2000

Efficacy and safety of recombinant factor VIIa in the prophylaxis of bleeding in various surgical procedures in hemophilic patients with factor VIII and factor IX inhibitors.

Patients with hemophilia may develop alloantibodies (inhibitors) directed toward the substitution factor. In the long term, this complication significantly affects around 15% of hemophilia A patients and 2-5% of hemophilia B patients suffering the severe class of disease (critical functional factor level <0.01 IU/mL). The typical consequence of a newly developed inhibitor is that the patient can no longer take advantage of the principles of modern hemophilia management, including safe and early treatment of bleeding and prophylactic use of concentrate in prevention of bleeding. Moreover, problems that are normally solved by means of a surgical procedure covered by the usual concentrate will be regarded as difficult and are likely to be associated with risk of untoward bleeding if high-titer inhibitors are present. Over the past decade, considerable experience has been collected illustrating that surgery may be performed quite safely in the patient with inhibitors if hemostasis is assisted by a new hemostatic agent, an activated recombinant factor VII molecule (rFVIIa). Although only one controlled randomized surgical study has been presented, cumulated data from this and from other, less formal studies on the use of rFVIIa in hemophilic inhibitor surgery have illustrated that a vast variety of different surgical procedures can be accomplished with none of the life-threatening bleeding complications that would be anticipated if no hemostatic treatment was administered. The aim of the present review is to present a multiplicity of surgical procedures that have been carried out during the clinical development of rFVIIa. Further, an update of 21 surgical procedures in inhibitor patients from the center of the author will be reviewed and discussed.

Autoantibodies↗
PubMed1997

Stable gene transfer and expression of human blood coagulation factor IX after intramuscular injection of recombinant adeno-associated virus.

We sought to determine whether intramuscular injection of a recombinant adeno-associated virus (rAAV) vector expressing human factor IX (hF.IX) could direct expression of therapeutic levels of the transgene in experimental animals. High titer (10(12)-10(13) vector genomes/ml) rAAV expressing hF.IX was prepared, purified, and injected into hindlimb muscles of C57BL/6 mice and Rag 1 mice. In the immunocompetent C57BL/6 mice, immunofluorescence staining of muscle harvested 3 months after injection demonstrated the presence of hF.IX protein, and PCR analysis of muscle DNA was positive for AAV DNA, but no hF.IX was detected in mouse plasma. Further studies showed that these mice had developed circulating antibodies to hF.IX. In follow-up experiments in Rag 1 mice, which carry a mutation in the recombinase activating gene-1 and thus lack functional B and T cells, similar results were seen on DNA analysis of muscle, but these mice also demonstrated therapeutic levels (200-350 ng/ml) of F. IX in the plasma. The time course of F.IX expression demonstrates that levels gradually increase over a period of several weeks before reaching a plateau that is stable 6 months after injection. In other experiments we demonstrate colocalization of hF.IX and collagen IV in intersitial spaces between muscle fibers. Collagen IV has recently been identified as a F.IX-binding protein; this finding explains the unusual pattern of immunofluorescent staining for F.IX shown in these experiments. Thus rAAV can be used to direct stable expression of therapeutic levels of F.IX after intramuscular injection and is a feasible strategy for treatment of patients with hemophilia B.

Animals↗
PubMed2002

[Sal I, Nru I and Mse I restriction fragment length polymorphisms of factor IX gene in Chinese Han people].

The purpose of this study is to investigate the Sal I, Nru I and Mse I restriction fragment length polymorphisms (RFLPs) of factor IX gene in Chinese Han people. The frequencies of FIX-192 and FIX-793 for A and G, and FIX-698 for T and C were analyzed by polymerase chain reaction (PCR) in unrelated normal Chinese Han people. A sample of 214, 210 and 206 unrelated X chromosomes were analyzed for FIX-192 and FIX-793 and FIX-698, respectively. The results showed that the frequencies for FIX-192 were 0.878 for A and 0.122 for G, with a heterozygosity rate of 0.213, and the frequencies for FIX-793 were 0.552 for A and 0.448 for G, with a heterozygosity rate of 0.494, the frequencies for FIX-698 were 0.311 for T and 0.689 for C, with a heterozygosity rate of 0.429. It was concluded that the SalIand NruI and MseI RFLPs of FIX gene may be useful markers for carrier detection and prenatal diagnosis in Chinese families with hemophilia B patients.

China↗
PubMed1987

Two sisters with a distal deletion at the Xq26/Xq27 interface: DNA studies indicate that the gene locus for factor IX is present.

Two sisters with premature menopause and a small deletion of the long arm of one of their X chromosomes [del (X)(pter----q26.3:)] were investigated with polymorphic DNA probes near the breakpoint. The deleted chromosome retained the factor IX (F9) locus and the loci DXS51 (52A) and DXS100 (pX45h), which are proximal to F9. However, the factor VIII (F8) locus was not present, nor were two loci tightly linked to this locus, DXS52 (St14) and DXS15 (DX13). This deletion refines the location of the F9 locus to Xq26 or to the interface Xq26/Xq27, thus placing it more proximally than has been previously reported. The DNA obtained from these patients should be valuable in the mapping of future probes derived from this region of the X chromosome.

Adult↗
PubMed2004

Transfusion-transmitted virus is not present in factor IX concentrates commonly used to treat haemophilia B.

Transfusion-transmitted virus (TTV) is a potential cause of post-transfusion hepatitis in patients with haemophilia. Plasma-derived clotting factor concentrates currently undergo processes that are effective in removal and inactivation of viruses such as HIV, hepatitis B and C; however, their effectiveness with respect to TTV is unknown. To determine if TTV DNA is present in plasma-derived concentrates of factor IX, we tested 14 lots of Mononine and compared the results with BeneFix. Nucleic acid isolation, followed by a two-round polymerase chain reaction (PCR) and agarose gel analysis indicated that all 17 lots were negative for TTV. Although TTV may be considered an emerging pathogen, no evidence of the virus was detected in the commercially available plasma-derived concentrate of FIX most commonly used to treat haemophilia B.

Circoviridae Infections↗
PubMed1998

Calcium binding to the first EGF-like module of human factor IX in a recombinant fragment containing residues 1-85. Mutations V46E and Q50E each manifest a negligible increase in calcium affinity.

The first EGF-like module of human coagulation factor IX contains a single functionally important calcium ion binding site. We have now shown the dissociation constant for this site to be approximately 160 microM in a recombinant protein fragment consisting of residues 1-85 in human fIX. This represents a approximately 10-fold increase in affinity as compared with the isolated EGF module (residues 46-85). The Gla module (here with Glu instead of Gla) thus increases the affinity of the EGF module calcium ion binding site. Each of two mutations, V46E and Q50E, made to investigate whether the extra negative charge would increase the affinity of the calcium binding site manifested a negligible increase in affinity.

Amino Acid Sequence↗
PubMed1979

Factor IX complex.

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Disseminated Intravascular Coagulation↗
PubMed2006

Successful transduction of liver in hemophilia by AAV-Factor IX and limitations imposed by the host immune response.

We have previously shown that a single portal vein infusion of a recombinant adeno-associated viral vector (rAAV) expressing canine Factor IX (F.IX) resulted in long-term expression of therapeutic levels of F.IX in dogs with severe hemophilia B. We carried out a phase 1/2 dose-escalation clinical study to extend this approach to humans with severe hemophilia B. rAAV-2 vector expressing human F.IX was infused through the hepatic artery into seven subjects. The data show that: (i) vector infusion at doses up to 2 x 10(12) vg/kg was not associated with acute or long-lasting toxicity; (ii) therapeutic levels of F.IX were achieved at the highest dose tested; (iii) duration of expression at therapeutic levels was limited to a period of approximately 8 weeks; (iv) a gradual decline in F.IX was accompanied by a transient asymptomatic elevation of liver transaminases that resolved without treatment. Further studies suggested that destruction of transduced hepatocytes by cell-mediated immunity targeting antigens of the AAV capsid caused both the decline in F.IX and the transient transaminitis. We conclude that rAAV-2 vectors can transduce human hepatocytes in vivo to result in therapeutically relevant levels of F.IX, but that future studies in humans may require immunomodulation to achieve long-term expression.

Adult↗
PubMed1997

Persistent systemic production of human factor IX in mice by skeletal myoblast-mediated gene transfer: feasibility of repeat application to obtain therapeutic levels.

Myoblast-mediated gene transfer and its repeated applications were tested for achieving a long-term stable systemic production of human factor IX (hFIX) at a therapeutic level in SCID mice. Primary skeletal myoblasts were stably transfected with a hFIX expression plasmid vector, pdLMe4 betaA-hIXm1, which contains a hFIX minigene under the control of a beta-actin promoter with muscle creatine kinase enhancers. Myotubes derived from the myoblasts produced 1,750 ng hFIX/10(6) cells/24 hours in culture. hFIX secretion by the myoblasts and thereof derived myotubes were equally efficient, and myotubes were shown to have a sufficient secretory capacity to handle a substantially elevated production of hFIX. After intramuscular injection of 5, 10, and 20 x 10(6) myoblasts, SCID mice stably produced hFIX into the systemic circulation proportional to the number of implanted cells, and the expression levels were maintained for at least up to 10 months (end of the experiment). Additional cell injections administered to animals that originally received 10 x 10(6) cells approximately 2 months later elevated the systemic hFIX levels to an average of 182 +/- 21 ng/mL, a therapeutic level, which persisted for at least 8 months (end of the experiment). These results indicate that long-term, stable systemic production of hFIX at therapeutic levels can be achieved by repeated application of myoblast-mediated gene transfer.

Animals↗