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Factor IX
See also Coagulation proteins
General information
Factor IX is used as substitution therapy in patients with hemophilia B. Although the half-lives of recombinant and plasma factor IX products are comparable, the in vivo recovery of recombinant factor IX is 28% lower than a highly purified plasma-derived product. To treat hemorrhage the dosage of recombinant factor IX needs to be 20% higher than plasma-derived products to increase the circulating factor IX activity to 1% per IU of recombinant factor IX given [ ].
General adverse effects and adverse reactions
Mild adverse reactions to factor IX include discomfort at the infusion site, fever, dizziness, allergic rhinitis, and light-headedness [ ].
Gene therapy
Trials of gene therapy in hemophilia (also known as Christmas factor) A and B, to determine safety and efficacy, are under way [ ]. Three patients with hemophilia B were treated in a phase I trial with a recombinant adenovirus-associated vector expressing human blood-coagulation factor IX [ ]. There was no evidence of formation of inhibitory antibodies against factor IX. In a phase I trial with a recombinant adenovirus-associated vector expressing human blood-coagulation factor IX, there was no evidence of germ-line transmission of vector sequences [ ].
The hazards of current vectors include insertion mutagenesis, immunogenesis, hepatotoxicity, and carcinogenic effects. In particular, retroviral vectors have a considerable carcinogenic potential. Adenoviruses, which do not integrate into the genome and consequently have only a transient effect, are considered to be safer. Also adeno-associated viruses have a low pathogenic potential in humans, as do lentiviruses.
Organs and systems
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