Successful of Immune Tolerance Induction (R-ITI) with Simoctocog Alfa (rhFVIII) in Hemophilia a Patients and High-Titer Inhibitors

Abstract

Backgroud: The appearance of inhibitors (INH) is the most serious complication in hemophilia A (HA) patients. The primary objective is their eradication. Usually the primary ITI was performed with the same concentrate causing INH development, but which replacement factor to be use in case of ITI-R is still debatable. We report two successful cases of ITI-R with simoctocog alfa (rhFVIII) performed in two different Italian Hemophilia Centers, while three other cases are still ongoing. Case Report: Case-1: Adult man with moderate HA who developed INH after surgery and concomitant switch to another concentrate (octocog-alfa 2nd gen). The patient refused the ITI treatment immediately after the inhibitors appearance, and was then put on prophylaxis with bypassing agents for several months. First ITI was then started with pdFVIII/vWF at 200 IU/kg/day, inhibitor titer reached its historical peak (134 BU/ml) two months later and progressively decreased to 15 BU/ml, but without ever disappearing. This ITI was stopped after nineteen months. A second ITI was then tried with high dose regimen of morocotocog-alfa, but also in this case the mean INH titer remained steadily high (21 BU/ml) and this treatment was considered failed after fifteen months from the onset. A new ITI-R was then started when the INH titer was 74 BU/ml, with simoctoctocog-alfa (rhFVIII), at 200 IU/kg/day. INH progressively decreased and 7 months later disappeared ( Disclosures No relevant conflicts of interest to declare.