PB0007 - Post-partum Acquired Haemophilia A in the COVID era – building the case for Emicizumab?

Background: Both de-novo and relapse of Acquired Haemophilia A (AHA) have been reported following SARS-CoV-2 infection and vaccination suggesting virus‐induced immune dysregulation as a potential mechanism.

The current standard of care in the potentially fatal AHA, requires the use of bypassing agents (BPA) or porcine FVIII to achieve haemostasis and immunosuppression to suppress autoantibody production. The bispecific antibody emicizumab now offers the possibility to achieve the former and reduced need for the latter but is only approved solely for use in congenital haemophilia A.

Aims: We present a cluster of three AHA cases presenting between April to June 2021 at a single tertiary centre. Notably each patient received recent BNT162b2(Pfizer) vaccination.

Methods: Bypassing therapy and steroids were commenced with response in two cases. One case remained refractory to BPA, porcine FVIII, steroids and Azathioprine. Approval was sought for a subcutaneous biweekly injection of Emicizumab in order to avoid rituximab during the pandemic.

Results: In 10 months since initiation of emicizumab, no further bleeding and no thrombotic events have been reported. Factor VIII (chromogenic) is now detectable in all patients.

Conclusion(s): The close interaction between SARS‐Cov‐2 and the haemostatic system has been evident in the COVID era. The unusual clustering of cases presented here suggests that antibody responses to SARS‐Cov‐2 infection or vaccine may cross-react with coagulation factors resulting in the immunohematological phenomenon of AHA.

Furthermore, to our knowledge this is the first use of Emicizumab in acquired haemophilia in the post-partum period. As well as providing excellent haemostatic efficacy and potential cost-effectiveness, emicizumab provides several advantages for a new mother during the COVID-19 pandemic. These include a return to home, contact with family and minimal attendance at hospital as well as avoiding immunosuppression conferring increased risk of infection and loss of protection from vaccinations. We note the recent application for use of emicizumab in AHA.