Articles

HMB-001: Novel treatment for Glanzmann thrombasthenia

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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Acquired haemophilia A

BJH - volume 10, issue 4, june 2019

R.E.G. Schutgens MD, PhD, K. van Galen MD

Acquired haemophilia A is a potentially severe condition characterised by spontaneous bleeding episodes. Direct recognition and prompt treatment are mandatory. Diagnostic coagulation assays show an isolated prolonged activated partial thromboplastin time, not correcting in a mixing assay. An isolated decrease of factor VIII activity together with the presence of a neutralising antibody confirm the diagnosis. Treatment consists of cessation of a possible bleed and the eradication of the neutralising antibody.

(BELG J HEMATOL 2019;10(4):146–52)

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