Abstract Number: PB0630
Meeting: ISTH 2021 Congress
Background: Approximately 20-30% of severe hemophilia A patients develop inhibitor, causing more frequent bleeding episodes. Immune tolerance induction (ITI) therapy is a mandatory treatment option. During ITI, patients have bleeding risk, as a result, prophylaxis with bypassing agents has been reported. Emicizumab, a bispecific antibody to factor IXa and factor X, has been used as prophylactic treatment among hemophilia A patient with inhibitor.
Aims: To report the benefit of prophylactic emicizumab in enhancing ITI in a boy with severe hemophilia A and high inhibitor titer.
Methods: A descriptive report.
Results: Case report: A 2-year-old boy with severe hemophilia A developed inhibitor of 16.9 Bethesda units (BU) after receiving factor VIII concentrates to treat 2 subdural hemorrhages. At 10 years of age, he exhibited extensive intracerebral bleeding inducing obstructive hydrocephalus requiring bilateral ventriculostomy. He required aPCC 82,500 units, rFVIIa 140 mg, and plasma exchange with high dose factor VIII concentrates (54,530 units) to control bleeding resulting in being bedridden. The ITI was initiated at the inhibitor of 140 BU and historic peak inhibitor of 3,360 BU with EHL factor VIII 100 units /kg 3 times weekly. The peak inhibitor during ITI was 380 BU with one of each episode of intramuscular and joint bleeding. The inhibitor titer was 17.2 BU at the end of the first year of ITI. Then, 3 mg/kg weekly for 4 doses and 6 mg/kg every 4 weeks of emicizumab prophylaxis was added in the second year of ITI. The inhibitor further declined to 0.6 BU at the end of third year of ITI. He finally achieved a partially successful ITI at the end of 3.5 years of ITI. His factor VIII:C recovery was 60% and half-life at 5.5 hours.
Conclusions: Additional emicizumab resulting in zero bleeding was helpful in enhancing ITI in a hemophilia boy with very high inhibitor titer.
To cite this abstract in AMA style:Sirachainan N, Chuansumrit A, Parapakpenjune S, Wongwerawattanakoon P, Lertthammakiat S, Kadegasem P, Sasanakul W. Benefits of Prophylactic Emicizumab in Enhancing Immune Tolerance Induction in a Hemophiliac Boy with Very High Inhibitor Titer [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/benefits-of-prophylactic-emicizumab-in-enhancing-immune-tolerance-induction-in-a-hemophiliac-boy-with-very-high-inhibitor-titer/. Accessed December 6, 2021.
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