Short term efficacy of recombinant porcine factor VIII in patients with factor VIII inhibitors

Acquired Haemophilia A in four north European countries: survey of 181 patients

Acquired haemophilia A (AHA) is a rare bleeding disorder caused by acquired antibodies against coagulation factor VIII. In the Nordic countries, treatment and outcomes have not been studied in recent times. To collect retrospective data on patients diagnosed with AHA in the Nordic countries between 2006 and 2018 and compare demographic data and clinical outcomes with previously published reports, data were collected by six haemophilia centres: three Swedish, one Finnish, one Danish and one Estonian. The study included 181 patients. Median age at diagnosis was 76 (range 5-99) years, with even gender distribution. Type and severity of bleeding was comparable to that in the large European Acquired Haemophilia Registry study (EACH2). Bleedings were primarily treated with activated prothrombin complex concentrate (aPCC) with a high success rate (91%). For immunosuppressive therapy, corticosteroid monotherapy was used most frequently and this may be the cause of the overall lower clinical remission rate compared to the EACH2 study (57% vs. 72%). Survey data on 181 patients collected from four north European countries showed similar demographic and clinical features as in previous studies on AHA. aPCC was used more frequently than in the EACH2 study and the overall remission rate was lower.

Recombinant porcine factor VIII: Lessons from the past and place in the management of hemophilia A with inhibitors in 2021

The most serious complication of factor VIII (FVIII) replacement therapy is the occurrence of anti-FVIII alloantibodies that can strongly reduce or abolish the effect of human FVIII products. Bypassing agents to control bleeding episodes are recommended for these patients, but their efficacy is difficult to predict and monitor. FVIII products derived from porcine plasma had an important role in the treatment of hemophilia A for 50 years, from 1954 to 2004. Indeed, porcine FVIII could achieve hemostasis in patients in whom human FVIII products were ineffective. A recombinant porcine FVIII product is now available. This highly purified protein has the same biochemical and hemostatic properties, but much lower risks of infection and toxicity compared with plasma-derived porcine FVIII. The product is licensed in the United States and Europe for the treatment of acquired hemophilia A. However, this recombinant molecule could also be of clinical interest for people with inherited hemophilia A and inhibitors, particularly for the management of bleeding episodes in people receiving emicizumab as prophylactic treatment in the absence of anti-porcine FVIII antibodies.

Recombinant porcine FVIII for bleed treatment in acquired hemophilia A: findings from a single-center, 18-patient cohort

Acquired hemophilia A (AHA) is a rare bleeding disorder in which acquired autoantibodies to endogenous factor VIII (FVIII) decrease FVIII activity and lead to a bleeding phenotype. A substantial majority of individuals who develop AHA present with severe bleeding. Effective treatment requires both immunosuppressive therapy and prompt hemostatic treatment. Bleeding is commonly treated with bypassing agents (BPAs) such as recombinant activated FVII (rFVIIa) or activated prothrombin complex concentrates Disadvantages to BPAs include the inability to monitor response with standard laboratory assays, inconsistent hemostatic efficacy, and thrombosis. Recombinant porcine FVIII (rpFVIII: Obizur, Baxter, Deerfield, IL) was approved by the US Food and Drug Administration (FDA) for bleed treatment in AHA in 2014, and has the advantage of laboratory monitoring of FVIII activity levels and known hemostatic efficacy in the presence of anti-human FVIII inhibitors and after failure of BPAs. Using an algorithm-based approach, rpFVIII has been used to successfully treat 18 patients with AHA at our center with substantially lower doses than the current FDA-recommended dosing. Additionally, data from our cohort show that the preexposure anti-porcine Bethesda titer does not reliably predict the clinical response to rpFVIII treatment and is not correlated with the anti-human Bethesda titer. We also present data showing lower total rpFVIII use for initial bleed resolution when rpVIII is used upfront, as compared with use as rescue therapy. We validated our dosing algorithm, which uses much lower than FDA-recommended doses with 14 more patients than in our previously reported patient series.

Should emicizumab be used in patients with acquired hemophilia A?

Emicizumab is currently approved to prevent bleeding in patients with congenital hemophilia A with or without neutralizing antibodies (inhibitors) against factor VIII (FVIII). Here, we present a case-based discussion of its potential use in acquired hemophilia A (AHA), a severe bleeding disorder caused by autoantibodies against FVIII. State-of-the-art management is based on bypassing agents (recombinant factor VIIa, activated prothrombin complex concentrate) and recombinant porcine FVIII; immunosuppressive therapy (corticosteroids, rituximab, cyclophosphamide) is used to suppress autoantibody formation. Case reports and one series suggest that emicizumab can reduce the risk of bleeding and the requirement for hemostatic therapy until remission of AHA is achieved. Further, it may allow to postpone the start of immunosuppressive therapy or to use less intense regimens. However, the risk-benefit assessment of emicizumab in AHA is difficult because demographic and clinical characteristics are different compared with congenital hemophilia. Prospective clinical trials are needed before the use of emicizumab can be recommended in AHA.