Recombinant porcine sequence factor VIII (rpFVIII) for acquired haemophilia A: practical clinical experience of its use in seven patients

Introduction: A recombinant porcine factor VIII B-domain-deleted product (rpFVIII; OBIZUR, Baxalta Incorporated, Deerfield, IL 60015, USA) was recently approved for treatment of bleeding episodes in adults with acquired haemophilia A (AHA) in the United States. To date, no clinical experience outside the registration study has been reported.

Aim: To describe early clinical experience using rpFVIII for AHA.

Methods: A retrospective chart review of seven patients with AHA treated with rpFVIII at four institutions from November 2014 to October 2015.

Results: The time to diagnosis of AHA ranged from 5 days to 6 weeks. Six major and one other bleed were treated with rpFVIII following unsatisfactory bypassing agent (BPA) therapy. Good haemostatic efficacy was seen in five of seven cases. rpFVIII loading doses of 100 (n = 6) or 200 U kg^-1 (n = 1) increased FVIII activity from <1 to 9% at baseline to 109-650% within 0.25-7 h in six of seven cases. Subsequent median doses ranged from 30 to 100 U kg^-1 for 3-26 days. No rpFVIII-related adverse events were reported. Three patients survived with inhibitor eradication, one with persistent inhibitor, two died with inhibitors present and one was discharged and later died from unrelated causes.

Conclusions: rpFVIII showed good haemostatic efficacy with no recurrences in most cases, with consumption substantially less than in the registration study. Treatment decisions were based on FVIII activity levels and clinical assessment. The ability to titrate rpFVIII dose using FVIII activity was considered advantageous compared with BPA therapy. Notable delays in diagnosis were observed.