What is your approach to the use of porcine FVIII in acquired hemophilia A?¶
Answer: Porcine FVIII (susoctocog alfa, Obizur) is a B-domain–deleted porcine FVIII product that shares 80–85% homology with human FVIII, so it may escape the anti-human FVIII antibodies seen in acquired hemophilia A (AHA). It is considered standard for hemostatic management of bleeding in AHA, alongside bypassing agents.
- Cross-reacting inhibitors are common. Stephen et al. found that 52% of one cohort had cross-reacting anti-porcine antibodies. A higher inhibitor titer (BU) predicted both a cross-reacting inhibitor and lack of response to Obizur. If an anti-porcine inhibitor is suspected, it should be quantified.
- Dosing. The FDA label and studies use 200 U/kg, then adjust to clinical response and FVIII activity.
- Lower doses may suffice. In our experience lower doses can still give an excellent response — consistent with other published reports that lower doses can be safe and product-sparing.
- Our approach: individualize to severity of bleeding, availability of rapid coagulation testing, staff familiarity, and the probability of a cross-reacting inhibitor.
Source: International recommendations on the diagnosis and treatment of acquired hemophilia A