Regulatory Decision Summary for Obizur

Obizur was designed to address an important unmet medical need in patients with acquired hemophilia A (AHA). Unlike the available therapies, Obizur re-establishes the normal physiologic clotting mechanism by correction of the hemostatic defect via the intrinsic coagulation pathway even in the presence of inhibitors to human factor VIII.

Current treatment options in acquired hemophilia include bypassing agents such as recombinant factor VIIa or an activated prothrombin complex concentrate. The choice of using of a recombinant factor VIII with excipients containing no animal-derived products of the final active substance presents an advantage especially regarding viral safety.

Bypassing agents are associated with a risk of thrombotic adverse events, and do not have a useful mean of monitoring efficacy whereas Obizur has the ability to monitor efficacy by standard measures which is a major contribution to the improvement of patient care.

Data from pivotal trial OBI-1-301 support the benefit of Obizur treatment for response and effective control of serious bleeding episodes in AHA. However, there were insufficient data submitted to assess the efficacy of this product to treat subsequent bleeds or to treat bleeds in specific sites, such as intra cranial haemorrhage.

The risks of treatment with Obizur are allergic reactions, inhibitor development to porcine FVIII, and thrombogenicity.

The development of anti-porcine antibodies may reduce the efficacy of this product to treat bleeds; however, the inhibitory antibodies against porcine FVIII were not associated with increased incidence of adverse events, and the maximum increase in titers was not related to dose.

Although somehow limited, the review of the information submitted indicates that the benefit associated with the intended use of Obizur in the small intended population outweighs the potential risks.