Study protocol for assessment of the coagulation potential of concomitantly used factor VIII concentrates in patients with haemophilia A with emicizumab prophylaxis (CAGUYAMA Study): a multicentre open-label non-randomised clinical trial

Masahiro Takeyama; Naoki Ozu; Shu Kasama; Masato Kasahara; Masanori Matsumoto; Midori Shima; Keiji Nogami

doi:10.1136/bmjopen-2023-072565

Study protocol for assessment of the coagulation potential of concomitantly used factor VIII concentrates in patients with haemophilia A with emicizumab prophylaxis (CAGUYAMA Study): a multicentre open-label non-randomised clinical trial

BMJ Open. 2023 Jul 10;13(7):e072565. doi: 10.1136/bmjopen-2023-072565.

Authors

Masahiro Takeyama¹, Naoki Ozu², Shu Kasama², Masato Kasahara², Masanori Matsumoto³, Midori Shima⁴, Keiji Nogami⁵

Affiliations

¹ Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan.
² Institute of Clinical and Translational Science, Nara Medical University, Kashihara, Nara, Japan.
³ Blood Transfusion Medicine, Nara Medical University, Kashihara, Nara, Japan.
⁴ Thrombosis and Hemostasis Research Center, Nara Medical University, Kashihara, Nara, Japan.
⁵ Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan roc-noga@naramed-u.ac.jp.

Abstract

Introduction: Emicizumab prophylaxis substantially reduces bleeding episodes in patients with haemophilia A (HA). The haemostatic efficacy of emicizumab in patients with HA is estimated as approximately 15% based on mimic activity of factor (F) VIII. Although it has been proven effective in preventing bleeding, its haemostatic effect during breakthrough bleeding or surgery is considered insufficient. Therefore, haemostatic management of emicizumab-treated patients with HA without inhibitors frequently requires FVIII replacement therapy. In haemostatic management of emicizumab-treated patients with HA, conventional FVIII dosage calculations are used in clinical practice without considering the coagulant effects of emicizumab.

Methods and analysis: In the CAGUYAMA study, 100 patients with HA without inhibitors will be enrolled for a maximum duration of 1 year, and samples of 30 events following the concomitant use of FVIII concentrates (30±5 U/kg) with emicizumab will be collected. An 'event' is defined as obtaining blood samples at preadministration and postadministration of FVIII concentrates during a breakthrough bleeding or a surgical procedure. Global coagulation assays will be used to measure the coagulation potential of the obtained samples. Clot waveform analysis (CWA) is used to identify the primary end-point, that is, the degree of improvement in the maximum coagulation rate at preadministration and post-administration of fixed-dose FVIII concentrations. The parameter obtained from CWA, which is triggered by an optimally diluted mixture of prothrombin time reagent and activated partial thromboplastin time reagent, is reported to be an excellent marker for assessing the degree of improvement of the coagulation potential in emicizumab-treated plasmas.

Ethics and dissemination: The CAGUYAMA study was approved by the Japan-Certified Review Board of Nara Medical University (Approval ID; nara0031). The study results will be communicated through publication in international scientific journals and presentations at (inter)national conferences.

Trial registration number: jRCTs051210137.

Keywords: Bleeding disorders & coagulopathies; Clinical trials; HAEMATOLOGY.

Publication types

Clinical Trial
Research Support, Non-U.S. Gov't

MeSH terms

Factor VIII / therapeutic use
Female
Hemophilia A* / drug therapy
Hemostatics*
Humans
Metrorrhagia*
Multicenter Studies as Topic

Substances

Factor VIII
emicizumab
Hemostatics