Abstract Number: PB0677
Meeting: ISTH 2021 Congress
Theme: Hemophilia and Rare Bleeding Disorders » Novel Biotherapeutics in Hemophilia
Background: Emicizumab, a subcutaneous factor VIII mimetic, was recently approved for severe hemophilia A patients. According to label, maintenance dosing is 6mg/kg/4 weeks, administered every 1, 2 or 4 weeks. Based on the reports of linear pharmacokinetics, a maintenance dose of 6mg/kg/4 weeks using entire vials only while varying the dosing intervals, was adopted at the Van Creveldkliniek in the Netherlands.
Aims: To evaluate emicizumab plasma concentrations and bleeding control on a maintenance dosing strategy using entire vials at 7 to 28-days’ intervals.
Methods: In a single-center study, all patients receiving emicizumab maintenance treatment for >2 months with emicizumab through concentrations available were eligible. Loading doses were exactly dosed according to the label. Maintenance treatment was 6mg/kg/4 weeks using entire vials at 7-28 days’ intervals. According to local protocol, emicizumab concentrations were measured after 2/3 and 12 months of maintenance treatment using a validated mass spectrometry-method. Bleeding data were extracted from patient files. Patients were instructed to contact the center in case of (suspected) bleeding.
Results: During the study period 33 patients had received a median of 157 days (P25-P75 (IQR) 112-391) of emicizumab maintenance treatment. Median age at treatment start was 17 years (IQR 6-51), median weight 66 kg (IQR 22-83), 30% had inhibitors and 88% severe haemophilia A. Median emicizumab dose was 5.9 mg/kg/4 weeks (IQR 5.6-6.2), administered in intervals of 7-28 days, with 42% using other intervals than 1-2x/week (Table 1). Median emicizumab concentrations were 73 µg/ml (IQR 47-82). Only 5/33 patients (15%) had concentrations <35µg/ml, including 3 confirmed non-adherent patients. Bleeding control was excellent: 79% had zero bleeds during follow-up, independent of emicizumab concentrations.
7 days |
8 days |
9 days |
12 days |
14 days |
18 days |
20 days |
21 days |
28 days |
|
30 mg | 1 | ||||||||
60 mg | 2 | 1 | 1 | 2 | 1 | 2 | |||
105 mg | 5 | 1 | 1 | 1 | 1 | ||||
120 mg | 3 | ||||||||
150 mg | 2 | 4 | 1 | 1 | |||||
165 mg | 1 | ||||||||
210 mg | 1 | ||||||||
255 mg | 1 | ||||||||
Total | 14 (42%) |
5 (15%) |
1 (3%) |
1 (3%) |
5 (15%) |
2 (6%) |
1 (3%) |
3 (9%) |
1 (3%) |
Conclusions: Dosing emicizumab using entire vials with varying intervals to achieve 6mg/kg/4weeks resulted in efficacious concentrations of emicizumab and excellent bleeding control. This dosing strategy can be applied to avoid spillage.
To cite this abstract in AMA style:
Fischer K, Donners AA, T Urbanus R, Kremer Hovinga IC, van Vulpen LF, R van der Valk P, van Galen KP, Uitslager N, Schutgens RE. Real-world Experience of Emicizumab Treatment Using Entire Vials Only [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/real-world-experience-of-emicizumab-treatment-using-entire-vials-only/. Accessed March 22, 2024.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/real-world-experience-of-emicizumab-treatment-using-entire-vials-only/