Immune tolerance induction, or ITI, in hemophilia A patients with inhibitor development against factor VIII (FVIII) appears to provide some protection against bleeding, as bleeding during ITI in patients from the PedNet registry was dependent on inhibitor titer and ITI regimen, according to Kathelijn Fischer, MD.
Of 218 registry patients who were born during 1990-2009 and who had clinically relevant inhibitors and available data on joint bleeding, 157 had bleeding for at least 3 months. They were followed for a median of 26 months starting at age 16 months, and most had high titer inhibitors (52% had titers of 5-199 BU, and 32% had titers greater than 200 BU).
The bleeding rates in 12 patients without ITI who were on prophylaxis were similar to those in 89 such patients without prophylaxis (0.3 and 0.4 bleeds/month, respectively); no significant difference was seen between the groups based on inhibitor titer, Dr. Fischer of University Medical Center Utrecht, The Netherlands reported at the annual meeting of the European Association for Haemophilia and Allied Disorders.
Similarly, the bleeding rate during ITI among those on prophylaxis did not differ significantly from the rate in those without prophylaxis (0.4 vs. 0.3/month, respectively), but the rate did increase significantly according to inhibitor titer: The rate increased from 0.05/month in the group with less than 5 BU, to 0.2/month in those with 5-199 BU, and to 0.5/month in the group with greater than 200 BU.
Further, while ITI dose did not affect bleeding, dosing frequency had a strong effect. The median rate with nondaily dosing in 36 patients vs. daily dosing in 63 patients was 0.4/month vs. 0.2/month, respectively, Dr. Fischer said.
She reported having no disclosures.