The International Immune Tolerance Induction Study and its follow-up study on Japanese hemophilia A patients with inhibitors.

The International Immune Tolerance Induction (I-ITI) Study in hemophilia A patients with inhibitors included 16 Japanese patients among a total of 115 test subjects. The results within this group of Japanese patients were 11 cases of I-ITI off-study, three cases of I-ITI on-study, and two cases of tolerance on prophylaxis. There was no significant difference in success rate between the low-dose and high-dose groups (Study I). Successively, independent follow-up survey in Japan was conducted in 14 cases, with consent (Study II). Ten cases were off-study at the end of the I-ITI Study. Of these 10 cases, seven of seven successful cases remained clinical successes at the end of the follow-up study, one partial success became a full success while a second relapsed, and one failure was subsequently evaluated as a partial success. Four cases that were on-study at the end of I-ITI Study were classified as three successes and one failure at the end of the follow-up study. As a result, the status at the end of follow-up study was: 11 ITI successes (78.6 %); one partial success; one failure; and one relapse. Thus, the ITI follow-up study was helpful in providing a long-term prognostic determination of inhibitors.