How Obizur works
Patients with acquired hemophilia have blood clotting problems due to the presence of antibodies that target the clotting factor VIII. Factor VIII is one of the proteins required for normal blood clotting. Patients with acquired hemophilia experience bleeding in the internal organs, muscles, and joints.
Obizur is a recombinant factor VIII that is synthesized by a gene that carries the instructions to make factor VIII in pigs. Obizur mimics the functioning human factor VIII but it slightly different structurally. Therefore, it can replace the human factor VIII without being recognized and deactivated by the antibodies in the patients’ blood and help in blood clotting.
Obizur in clinical trials
The approval of Obizur for the treatment of acquired hemophilia was based on data from a Phase 2/3 multicenter clinical trial (NCT01178294). This international study assessed the safety and efficacy of Obizur in 28 patients with acquired hemophilia (median age 70 years). The patients were initially treated with 200 U/kg of Obizur followed by additional doses depending on their response and factor VIII activity levels in the blood. Patients also received immunosuppressive treatment during the study.
Within 24 hours of treatment, Obizur either stopped or reduced bleeding in all patients, meeting the primary endpoint of a positive clinical response. Compared to the start of the study, a significant increase in factor VIII activity levels was reported in all the patients after 24 hours of treatment. No adverse effects were reported.
A post-marketing multi-center study (NCT02610127) is surveilling at least 60 adult patients with acquired hemophilia who are being treated with Obizur to assess the effectiveness and safety of the treatment in a real-world setting. The ongoing observational study is an attempt to collect patient data post-FDA approval to continue monitoring any safety concerns associated with Obizur use.
An ongoing non-interventional study (NCT03199794) is evaluating the effectiveness and safety of Obizur prescribed to people with acquired hemophilia by their treating physicians. The duration of this international study is 180 days. This is a real-life study enrolling approximately 50 acquired hemophilia patients, age 18 and older, in Austria, Germany, Italy, and the Netherlands.
Obizur may cause a number of side effects. These include:
- Nausea or vomiting
- Burning at the site of injection
- Low blood pressure
- Chest tightness, tingling, or rapid heartbeat
- Breathing problems like wheezing
Some patients may develop inhibitory antibodies to the porcine factor VIII, making the treatment ineffective. In such cases, it is recommended to consider alternate therapeutic options in consultation with the patient’s care team.
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