Hemophilia is a blood disorder that is characterized by a shortage of specific clotting factors that help to form blood clots and stop bleeding.
The primary treatment for hemophilia is replacement therapy that supplies the clotting factors to hemophilia patients who lack them. Other approved hemophilia treatments include desmopressin, antibodies, and bypassing agents.
Recombinant clotting factor concentrates
Recombinant clotting factors are genetically engineered and resemble healthy human clotting factors.
For treating hemophilia A, recombinant clotting factors VIII are used, including Kovaltry, Advate, Afstyla, Nuwig, Recombinate, and Xyntha. Recombinant factors IX, which include BeneFix, Ixinity, and Rixubis, are used to treat hemophilia B.
Extended half-life products
Recombinant clotting factors can be modified in a way that makes them more stable, so they are not broken down as easily and “live” longer. The advantage of longer-living molecules is that patients can reduce the frequency of injections.
One way to increase the stability of recombinant clotting factors is by PEGylation, which involves the attachment of the molecule polyethylene glycol (PEG) to the clotting factor. Bax 855, Adynovate (which is PEGylated Advate), and N8-GP are PEGylated clotting factors approved for the treatment of hemophilia A. Refixia (N9-GP) is a PEGylated clotting factor approved for the treatment of hemophilia B.
Another approach to extend the half-life of clotting factors is with fusion to albumin, which is a protein that naturally occurs in the blood. The albumin-fused factor IX, CSL654 (Idelvion), is a treatment for hemophilia B.
The third approach is the fusion of a recombinant clotting factor to the so-called Fc fragment (fragment crystallizable region) of antibodies. Eloctate is an Fc-fused product for hemophilia A and Alprolix for hemophilia B.
Plasma-derived clotting factor concentrates
Plasma is the liquid part of blood, which contains proteins such as albumin, antibodies, and clotting factors. Clotting factors may be purified from the plasma of healthy donors and used to treat hemophilia patients. Hemofil-M is a product for hemophilia A, while AlphaNine SD and Mononine are treatments for hemophilia B.
Some products from plasma-derived clotting factors contain von Willebrand factor, another clotting protein. The medications Alphanate, Humate-P, and Koate-DVI are treatments for hemophilia A. Alphanate and Humate-P also are used for the treatment of Von Willebrand Disease, a condition in which individuals do not have sufficient amounts of von Willebrand factor.
Hemoleven is a factor XI concentrate for the treatment of hemophilia C. It is available in Europe but not in the U.S.
Desmopressin
Desmopressin resembles vasopressin, a naturally occurring hormone that stimulates the release of clotting factor VIII and von Willebrand factor. The desmopressin formulations Stimate (a nasal spray) and DDAVP (tablet form) are used to treat mild forms of hemophilia A and von Willebrand disease.
Antibodies
Hemlibra is an antibody that binds clotting factors IXa and X. By bringing these two molecules together, it facilitates clotting.
Bypassing agents
Patients who are treated with clotting factors may develop antibodies or inhibitors against these factors, which make the treatments ineffective. Bypassing agents are used as an alternative treatment in these patients. They can also be used to treat acquired hemophilia, an autoimmune condition in which immune cells mistakenly attack clotting factors.
Feiba contains several clotting factors that help convert prothrombin into thrombin. Thrombin is involved in the formation of blood clots.
NovoSeven RT resembles human clotting factor VIIa, which promotes the production of fibrin, a protein required for clot formation.
Feiba and NovoSeven RT can be used for the treatment of several forms of hemophilia.
Obizur is a recombinant factor VIII derived from pigs that is used for the treatment of acquired hemophilia A. Patients with acquired hemophilia develop antibodies against their own human factor VIII, but these antibodies do not attack pig-derived factor VIII.
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