PB1306 - Inhibitor recurrence following immune tolerance induction in a hemophilia A patient with inhibitor post COVID-19 infection

Background: Immune tolerance induction (ITI) in patients with congenital hemophilia A (HA) with inhibitor is successful in up to 70 %. The probability and risk factors of inhibitor recurrence following successful ITI are not well understood.

Aims: Share a case of recurrent inhibitor following successful ITI post COVID-19 infection.

Methods: A 48 years old male with nonsense mutation congenital HA , occurred high responder inhibitor during traumatic operation about 21 years of age. He had historical peak inhibitor titer 224 BU, Petterson’s score 56, HBV and HCV infection. Patient received ITI (at start titer, 3.4 BU) with Nuwiq 100 iu/kg/day for 2 years and shift to afstyla 50 iu/kg/day for year then tapping to 35 iu/kg/biw on prophylaxis therapy later. The peak titer during ITI was 167 BU and in vivo recovery was 70% with half life 7 hrs . He had received BNT vaccine two dose but got COVID-19 infection post successful ITI with FVIII < 1 % and anti-FVIII 5.6 BU three month later.

Results: This case was successful ITI under rFVIII but inhibitor recurrent was noticed post COVID-19 infection. He would be received rescue ITI with haemate-P and emicizumab.

Conclusion(s): Management of HA patients with inhibitor is still a challenge until now. As a break of COVID-19 infection or vaccination, clinician and laboratory should be aware of this potential adverse event.