Hemophilia recombinant factor VIII

Natural source may carry risk of infection. Recombinant Factor VIII used to treat hemophilia A has helped reduce the incidence of HIV infection in hemophiliacs. Recombinant HbsAg is now used to immunize against hepatitis B, eliminating the risk of introducing a viral infection during vaccination. 

Clinical trials have demonstrated excellent efficacy with recombinant human factor VIII concentrates available as Recombinate and Kogenate. These recombinant factor VIII products are purified from the cell culture of plasmids, not viral DNA-transfected hamster cells and therefore do not express viral sequences. The addition of human serum albumin for stabilization, constitutes the sole possible source for human viral contamination. More recently recombinant factor IX has been genetically engineered by insertion of the human factor IX gene into a Chinese hamster ovary cell line. It has been proved to be safe and effective in the treatment of patients with hemophilia B. 

E Role in therapy Antihemophilic factor is indicated for the treatment of bleeding episodes or perioperative treatment in patients with hemophilia A. Prophylactic use has also been advocated for the prevention and/or reduction of bleeding episodes. The largest issue in treatment with antihemophilic factor is the choice of formulations because of the relative risk of viral transmission. Recombinant factor VIII has the lowest risk of transmission of blood-borne viruses, but its use may be limited due to cost and availability. 

VIII Hemophilia A 30-50% 100% for major bleeding or trauma 12 hours Recombinant factor VIII products Plasma-derived high purity concentrates Cryoprecipitate1 Some patients with mild deficiency will respond to DDAVP... 

Blood factor VIII (FVIII) is a glycoprotein with 2351 amino acids and 330 kDa. Its deficiency causes hemophilia A. The first products based on recombinant factor VIII to reach the market were Recombinate and Kogenate, expressed in CHO and BHK cells, respectively. Over the last decade, other rFVIII products were approved, with modifications to the molecule (e.g. deletion of the B-domain), in the formulation or in the production processes. 

Giles AR,Tinlin S, Hoogendoorn H, Fournel MA, Ng P, Pancham N. In vivo characterization of recombinant factor VIII in a canine model of hemophilia a (factor VIII deficiency). Blood 1988 72 335-9. 

Lusher JM, Arkin S, Abildgaard CF, et al. Recombinant factor VIII for the treatment of previously untreated patients with hemophilia A safety, efficacy, and development of inhibitors. N Engl J Med 1993 328(7) 453—9. 

In the past, hemophiliacs were treated with transfusions of a concentrated plasma fraction containing factor VIII. This therapy carried the risk of infection. Indeed, many hemophiliacs contracted hepatitis and AIDS. A safer preparation of factor VIII was urgently needed. With the use of biochemical purification and recombinant DNA techniques, the gene for factor VIII was isolated and expressed in cells grown in culture. Recombinant factor VIII purified from these cells has largely replaced plasma concentrates in treating hemophilia. 

Lyophilized factor VIII has been used as substitution therapy in patients with hemophilia A. Most, but not all, recombinant factor VIII (recFVIII) is structurally and immunologically similar to plasma-derived factor VIII, and it has been well tolerated by patients in clinical trials. A major concern about recombinant factor VIII has been the occurrence inhibitors (1). However, there is evidence that there is no difference in the occurrence of inhibitors between recombinant factor VIII and plasma-derived factor VIII (2). 

In two studies of previously untreated patients with severe hemophilia, who were given two different recombinant factor VIII products, the incidence of development of an inhibitor was comparable (about 30%) (29). 

In 31 previously untreated and minimally treated children with severe hemophilia A, who received full-length recombinant factor VIII (formulated with sucrose) for home therapy and surgery, there was no difference in the incidence of inhibitor formation compared with other recombinant products or plasma-derived products (2). 

Protein purification, introduced in the 1990s, produced high-purity concentrates with increased amounts of factor VIII or factor IX relative to the product s total protein content. Recombinant factor VIII and then factor IX also became available. The first-generation recombinant factor VIII products utilize human and animal proteins in culture and add human albumin as a protein stablilizer. Second-generation recombinant factor VIII concentrates removed albumin as a protein stabilizer, and the third-generation products lack human and animal proteins in the culture media. Finally, gene therapy for the treatment of hemophilia is now in the early stages of clinical trials. 

Bray GL, Gomperts ED, Courier S, et al. A multicenter smdy of recombinant factor VIII (Recombinate) Safety, efficacy, and inhibitor risk in previously untreated patients with hemophilia A. The Recombinate study group. Blood 1994 83 2428-2435. 

G.C. White II, S. Courier, G.L. Bray M. Lee, E. Gomperts, and the Recombinate Previously Treated Patient Study Group. A multicenter study of recombinant factor VIII (Recombinate ) in previously treated patients with hemophilia A. Thromb Hemost 1997 77 660-667. 

NZ BAY-14-2222 antihemophilic Kogenate FS Helixate FS, Kogenate SF Human recombinant factor VIII expressed in baby hamster kidney cells and purified by modified chromatography and then stabilized with sucrose Hemophilia... 

Recombinant DNA techniques have enabled the cloning of Factor VIII, which is missing from most patients with the inherited bleeding disorder hemophilia. Factor VIII is essential for proper blood clotting, and untreated hemophilia patients suffer from severe uncontrolled bleeding. Recombinant Factor VIII is used to restore clotting activity to the blood of hemophiliacs. 

Recombinant factor VIII Hemophilia B Recombinant factor IX Hemophilia A Lepirudin Heparin-inducer thrombocytopenia type II... 

The major concern associated with the use of concentrated clotting factors is the risk of viral transmission (primarily HIV and hepatitis B). This fear has somewhat attenuated the use of concentrated plasma fractions, even In diseases such as hemophilia. Ultrapure factor VIII concentrates produced using recombinant DMA technology have been approved for use. Frequently, however, the expense of these recombinant agents is the reason why the more traditional plasma Isolates are used—despite the possibility of viral transmission. 

Recombinant factor VIII Fc fusion protein Severe hemophilia A Biogen Idee... 

In past years, treatment for patients with hemophilia A has consisted of administration of cryoprecipitates (enriched in factor VIII) prepared from individual donors or lyophilized factor VIII concentrates prepared from plasma pools of up to 5000 donors. It is now possible to prepare factor Vlll by recombinant DNA technology. Such preparations are free of contaminating viruses (eg, hepatitis A, B, G, or HlV-1) found in human plasma but are at present expensive their use may increase if cost of production decreases. 

Clinical pharmacology Activated factor IX in combination with activated factor VIII activates factor X. This results ultimately in the conversion of prothrombin to thrombin. Thrombin then converts fibrinogen to fibrin, and a clot can be formed. Factor IX is the specific clotting factor deficient in patients with hemophilia B and in patients with acquired factor IX deficiencies. The administration of Coagulation Factor IX (Recombinant) increases plasma levels of factor IX and can temporarily correct the coagulation defect in these patients. 

Coagulation factors Recombinate (F VIII) Hemophilia rCHO, bleed-feed... 

Fig. 3.2. Schematic of recombinant AAV dual-vector strategies for gene therapy for hemophilia A. (A) depicts the individual expression of the 5 and 3 ends of the factor VIII protein followed by heterodimerization to generate a function protein. (B) shows concatamerized 5 and 3 vectors in the correct head-to-tail orientation. Splicing of vectors to remove the intron and inverted terminal repeats leads to expression of the entire factor VIII protein from a single mature mRNA transcript. ITR, AAV inverted terminal repeat SD, splice donor SA, splice acceptor An, poly A.

Many recombinant proteins that are not antibodies are also on the market for distinct applications (see Chapter 16). Examples are factor VIII for hemophilia A treatment (Bayer, 1993, produced from BHK cells), erythropoietin as an anti-anemic agent (Amgen, 1989, produced from CHO cells) and /1-interferon for the treatment of multiple sclerosis (Biogen and Serono, 1996, produced from CHO cells). 

Some hemophilia A and B patients develop antibodies against FVIII and FIX, respectively. This complicates the direct administration of these proteins. An alternative in these cases is treatment with active factor VII (FVIIa), which complexes with factor III in the presence of phospholipids and Ca2+, activating factor X, which, in normal patients, is activated by active factors VIII and IX. The commercial name of recombinant FVIIa expressed in BHK cells and produced by Novo-Nordisk is NovoSeven (Table 16.1). 

The first therapeutic recombinant DNA-derived coagulation protein licensed by the FDA was factor VIII for treatment of hemophilia A in 1992 [38]. This step forward was a landmark in hemophilia therapy. This biotechnology process reduced the theoretical risk of human-derived viruses and seemed to provide for an unlimited market supply although other human and animal proteins were often used in the manufacturing and formulation of many recombinant... 

Recombinant and high-purity coagulation factor products appear to have a greater tendency to induce inhibitors than human-derived concentrates of intermediate or low purity (7). These intermediate-purity or low-purity human-derived concentrates are probably more suitable for inducing immune tolerance in patients with hemophilia with inhibitors. It has been suggested that for immune tolerance a high content of Von Willebrand factor in factor VIII concentrates is required, although direct comparisons of different products have not been made (8). 

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