Abstract Number: VPB0208
Meeting: ISTH 2022 Congress
Background: Emicizumab prophylaxis reduces bleedings in the patients with hemophilia A (PwHA). A clinical study (HAVEN 7) including PwHA without inhibitors up to 12 months of age is currently ongoing, but it is not yet clear whether emicizumab affects infant PwHA.
Aims: To examine the coagulation potential of emicizumab in vivo or ex vivo in plasma collected from 0 to 42-month-old child PwHA (child-HA).
Methods: This study was approved by two institutional review boards and informed consent was obtained. Plasma from 27 child-HA patients up to 42 months of age, receiving emicizumab, a factor (F) VIII agent, or neither emicizumab nor FVIII agent (median age; 19 months) were enrolled. FVIII activity in PwHA receiving FVIII agents was reduced to < 1 IU/dL by the addition of anti-FVIII A2 monoclonal antibody. Samples of emicizumab-spiked plasma (ex vivo) or emicizumab-treated plasma (in vivo) were analyzed. Untreated plasma or emicizumab-treated plasma supplemented with anti-emicizumab antibody were used as reference samples, respectively. Global coagulation activity was measured and adjusted for maximum coagulation velocity (Ad|min1|) in a clot waveform analysis (CWA) and peak thrombin was measured using thrombin generation assay (TGA).
Results: Ad|min1| in 24 of the 27 cases was improved in the presence of emicizumab. The 3 child-HA which did not respond were 1, 23, and 31 months of age. Although 20 of the 27 cases showed an age-dependent increase in peak thrombin with emicizumab, 7 cases (0, 1, 1, 2, 8, 19, and 36 months) did not. An emicizumab-dependent increase in coagulant potential was shown in 18 cases by both Ad|min1| and peak thrombin, and in 8 cases by one parameter but not the other. Only 1 case (1 month of age) did not respond with either Ad|min1| or peak thrombin.
Conclusion(s): In general, emicizumab improved coagulant potential in child hemophilia A plasma evaluated by global coagulation assays.
To cite this abstract in AMA style:Takeyama M, Matsumoto N, Abe H, Harada S, Ogiwara K, Furukawa S, Soeda T, Nogami K. Coagulant potential of emicizumab in child hemophilia A patients [abstract]. https://abstracts.isth.org/abstract/coagulant-potential-of-emicizumab-in-child-hemophilia-a-patients/. Accessed October 2, 2023.
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