Abstract Number: PB1575
Meeting: ISTH 2020 Congress
Theme: Platelet Disorders and von Willebrand Disease » VWF and von Willebrand Factor Disorders - Clinical Conditions
Background: Alloantibody formation is a rare but serious complication of replacement therapy that can be accompanied by anaphylaxis reaction following re-injection of von Willebrand factor (VWF) concentrate in patients with type 3 von Willebrand disease (VWD).
Aims: This study is aimed to evaluate the presence of inhibitor in patients with type 3 VWD.
Methods: This study conducted on 99 patients with type 3 VWD. Laboratory diagnosis was performed by factor (F) VIII coagulant activity (FVIII: C), VWF antigen, and VWF: ristocetin cofactor. VWF and FVIII inhibitor titers were determined by a modified Nijmegen-Bethesda assay.
Results: Of 99 patients, 19 (~19.5 %,) were positive for inhibitor against VWF ranged from 2 to 80 Bethesda Unit (BU); most were high-titer, high responder inhibitor (n: 10, 58%). The mean age of diagnosis and the mean age at inhibitor detection were 3.7 and 20.5 years old, respectively. Hemarthrosis was observed in 41% of patients after inhibitor development. Before inhibitor formation, the majority of the patients (94%) received on demand regimen (Haemate®, CSL Behring, Marburg, Germany), while one patient received a prophylactic regimen (Wilate®, Octapharma, Lachen, Switzerland). Twelve patients (70.5%) with inhibitor showed an anaphylactic reaction following > 12 to 300 times exposure to Haemate® and 5 cases (29.5%) showed less severe allergic reactions to Haemate®. These 5 cases were still treated with Haemate®. Three, five, and one cases were switched to on-demand regimen with Wilate®, AryoSevenTM (AryoGen, Tehran, Iran), and FEIBA® (Baxalta Inc, Lexington, USA), respectively; none of them were effective. One case refused to receive treatment. Three cases were successfully managed by prophylaxis regimen with Haemate® (25 u/kg/ twice a week), AryoSevenTM (50 µg/kg/a day), and FEIBA® (50 u/kg/twice a month).
Conclusions: Inhibitor formation can significantly exacerbate the clinical presentations, therefore, early detection of major risk factors of inhibitor formation should be considered as a preventative program.
To cite this abstract in AMA style:
Bahoush GR, Tabibian S, Baghaipour MR, Ala F, Jazebi M, Dorgalaleh A, Hantooshzadeh R, Baghaipour N. Inhibitor Development in Patients with Type 3 von Willebrand Disease, a Comprehensive Study on a Large Number of Iranian Patients [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/inhibitor-development-in-patients-with-type-3-von-willebrand-disease-a-comprehensive-study-on-a-large-number-of-iranian-patients/. Accessed March 22, 2024.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/inhibitor-development-in-patients-with-type-3-von-willebrand-disease-a-comprehensive-study-on-a-large-number-of-iranian-patients/