Obizur (susoctocog alfa) is a man-made version of clotting factor VIII, of pig origin, that is approved to treat bleeding episodes in adults with acquired hemophilia.

The U.S. Food and Drug Administration approved Obizur in 2014. A year later, the European Commission authorized its use in the EU. Originally developed by Baxalta, the medication is now marketed by Takeda.

How does Obizur work?

Patients with acquired hemophilia have blood clotting problems because of the presence of antibodies that target proteins required for normal blood clotting, often one called factor VIII (FVIII).

Obizur is a recombinant, or man-made, version of FVIII produced by a gene that carries instructions to make the protein in pigs. This version mimics how human FVIII functions, but is slightly different structurally. Therefore, it can replace the human FVIII and help restore blood clotting without being recognized and deactivated by antibodies circulating in a person’s bloodstream.

Obizur in clinical trials

The approval of Obizur to treat acquired hemophilia was based on data from a multi-center Phase 2/3 trial (NCT01178294). This international study assessed the safety and efficacy of Obizur in 29 patients with acquired hemophilia. Patients were initially treated with 200 units/kg of Obizur, followed by additional doses depending on their response and FVIII activity levels. Patients also received immunosuppressive treatment during the study.

Within 24 hours, Obizur either stopped or reduced bleeding in all patients, meeting the primary endpoint, or goal, of a positive clinical response. This positive response was seen in all 18 patients evaluated at 16 hours, and in all but one who were assessed after eight hours.

Other details

Obizur is given as a shot directly into a vein. This therapy is available in single-dose bottles containing 500 units of its active ingredient per bottle. The recommended starting dose is 200 units/kg. Each dose should be taken every four to 12 hours, and frequency may be adjusted based on clinical response and FVIII levels.

Neutralizing antibodies developing against porcine FVIII is the most common adverse event associated with Obizur. In such cases, it’s recommended that alternative therapeutic options be considered in consultation with the patient’s care team.

Allergic reactions to Obizur also may occur, causing patients to experience burning at the site of injection, swelling under the skin, known as angioedema, hives, low blood pressure, chest tightness, and breathing problems, such as wheezing. In these cases, treatment should be stopped.

Obizur is not recommended for patients with congenital hemophilia A or von Willebrand disease.


Last updated: Feb. 11, 2022, by Teresa Carvalho MS


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