BJH - volume 16, issue 4, july 2025
M. Zivkovic PhD, Q. Van Thillo MD, PhD, P. Verhamme MD, PhD, R.T. Urbanus PhD, R.E.G. Schutgens MD, PhD
SUMMARY
Inherited rare bleeding disorders such as Glanzmann thrombasthenia currently lack preventive treatment options. Consequently, severe bleeding episodes are typically managed through platelet transfusions or repeated administrations of recombinant activated factor VII (rFVIIa). This article introduces HMB-001, a bispecific antibody engineered to bind endogenous FVIIa and direct it to sites of vascular injury by targeting TLT-1, a specific platelet receptor, which becomes active on the platelet surface upon injury. In preclinical studies involving non-human primates, HMB-001 was shown to extend the half-life of FVIIa, resulting in elevated plasma levels. In murine models, HMB-001 enhances the haemostatic efficacy of FVIIa by binding to the TLT-1 receptor on activated platelets. Additionally, ex vivo experiments with platelets from individuals with Glanzmann thrombasthenia demonstrate that HMB-001 facilitates the binding of FVIIa to activated platelets, thereby promoting clot formation. Collectively, these findings suggest that HMB-001 represents a promising new approach for the preventive management of bleeding in individuals with Glanzmann thrombasthenia and related disorders.
(BELG J HEMATOL 2025;16(4):169–75)
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