A new prospective, observational, case-only study will evaluate the effect of emicizumab on in vitro heparin-induced activating clotting time (ACT) increases using the i-STAT Alinity device in patients with severe hemophilia A and healthy volunteers. The recruitment process has not started yet.

The study is expected to enroll 15 adult male participants with severe hemophilia A who have been treated with emicizumab for at least 4 weeks. Those who have received an infusion of factor VIII within the past 5 days or who are using anticoagulants will not be included in the study.

ACT will be measured after in vitro spiking with unfractionated heparin of blood samples from patients with severe hemophilia A already treated with emicizumab as well as from blood samples from healthy volunteers with or without emicizumab.

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The researchers will monitor changes in in vitro heparin-induced ACT increases by emicizumab as the primary outcome measure. At present, the study protocol does not include any secondary outcome measures.

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The study is sponsored by the University Hospital, Grenoble, and is set to start in June 2023. The estimated primary completion date as well as the estimated study completion date is February 2025.

Emicizumab, a subcutaneous prophylactic treatment for patients with severe hemophilia A, provides only partial in vivo correction of plasma coagulation but significantly reduces the in vitro coagulation times involving the intrinsic pathway. As ACT is also activated through the intrinsic pathway, researchers suspect it may be shortened in people receiving the medication.

The i-STAT Alinity, a device used to monitor heparin therapies during cardiac surgeries and cardiac catheterizations, will be used to evaluate ACT for the first time in this study.


Impact of emicizumab on activated clotting time using the i-STAT Alinity Analyzer (EMISTAT). ClinicalTrials.gov. May 12, 2023. Accessed May 30, 2023.