Low-Dose Immune Tolerance Induction Works in Severe Hemophilia A With Inhibitors Below 40 Bethesda Units

Dutch hematologists examined results of 26 years of low-dose immune tolerance induction (ITI) therapy as a treatment regimen for inhibitory alloantibodies against factor VIII in patients with severe hemophiliaA.Twenty-one patients were treated with regular infusions of low-dose factorVIII (25 to 50 IU/kg) every other day or three times a week in an attempt to obtain immune tolerance.

In 18 of the 21 patients (86 percent), low-dose ITI was successful. A successful outcome was associated with both a pre-ITI titer and a maximum titer during ITI below 40 Bethesda Units (BU)/mL (P = 0.003). The time to success was also significantly shorter if the maximum titer during ITI was below 40 BU/mL (P = 0.04). In patients with low titer inhibitors (<5 BU/mL), this effect was even stronger (P = 0.033).

The investigators suggest that all patients with severe hemophilia A and a pre-ITI inhibitor titer below 5 BU/mL should be treated with low-dose ITI therapy, and those with pre-ITI titers below 40 BU/mL may also strongly benefit.