This study will enroll children who have hemophilia A with inhibitors who successfully
completed immune tolerance induction per the ISTH criteria (negative inhibitor titer,
recovery >66% of expected, and half-life of >6 hours with their current FVIII concentrate).
Previous to emicizumab, there was only one option for these patients which was to continue
FVIII therapy in a prophylaxis mode to prevent bleeding. There was a sense that the ongoing
FVIII served to maintain tolerance however no evidence for this notion exists and in fact
what limited data is available suggests that continuing FVIII may not be necessary simply to
maintain tolerance.
To figure out this question, this will be a randomized, controlled 2 arm study which will
randomize patients post-successful ITI to emicizumab plus weekly FVIII (for maintenance of
tolerance) versus emicizumab alone. Patients will be followed for up to 2 years. We aim to
enroll 52 subjects. The FVIII weekly arm can use any factor VIII concentrate and emicizumab
is standard of care for inhibitor and non-inhibitor patients.