Successful immune tolerance induction using efanesoctocog alfa in severe hemophilia A: a case series.
Aqsa Ashraf, Rebekah Kuhlman, Osman Khan et al.
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Case in brief
Two patients with severe hemophilia A and complex histories of FVIII inhibitors received immune tolerance induction with efanesoctocog alfa, initially at 100 U/kg three times weekly. Inhibitors became undetectable (<0.5 Bethesda Units) within 6 weeks in one patient and 3 months in the other, with FVIII recovery exceeding 90%. After dose reduction and transition to individualized once-weekly prophylaxis, both maintained functional FVIII activity and trough levels of 4%-6%; emicizumab was discontinued. They remained bleed-free without inhibitor recurrence.
What made this case unusual
Both patients had complex inhibitor histories, and efanesoctocog alfa-based immune tolerance induction was used for rescue or retreatment, with rapid inhibitor clearance followed by individualized once-weekly prophylaxis.
Diagnostic / clinical pearl
In these cases, inhibitor clearance was assessed alongside FVIII recovery; subsequent individualized prophylaxis maintained therapeutic trough levels without inhibitor recurrence.
Why it matters
The cases suggest efanesoctocog alfa-based immune tolerance induction may be a strategy to consider for patients with complex inhibitor histories, including rescue or retreatment.