Overall strategy for IST for acquired HA. Proposed therapies are based on prognostic risk factors (FVIII clotting activity and inhibitor titers in Bethesda Units, BU). The response could be assessed as a complete response or significant and sustained improvement on the FVIII:C and/or reduction of inhibitor titers at the end of 3 to 4 weeks. In the case of failure in achieving these outcomes, the therapeutic intervention should proceed with the subsequent regimen.