FRCPath Haem Part 1 MCQs-Haemostasis 461

A 22-year-old woman with Glanzmann thrombasthenia experiences recurrent spontaneous epistaxis and menorrhagia despite tranexamic acid. She has developed anti-GPIIb/IIIa antibodies following multiple platelet transfusions, making future platelet transfusions less effective. She is enrolled in the HMB-001 Phase 1/2 trial investigating a novel prophylactic therapy.

Which ONE of the following best describes the mechanism of action of HMB-001?

A. It binds activated factor X and thrombin to accelerate fibrin clot formation.

B. It is a bispecific antibody that bridges platelets and fibrin, promoting platelet incorporation into the developing clot independently of functional GPIIb/IIIa receptors.

C. It replaces the defective GPIIb/IIIa receptor on the platelet surface by gene transfer.

D. It increases plasma von Willebrand factor levels by stimulating endothelial release.

E. It inhibits fibrinolysis by blocking plasminogen activation.