Supplementum 293: Abstracts of the Swiss Oncology and Hematology Congress (SOHC) (Basel, Switzerland, November 19−21, 2025)

Background and objective: Glanzmann thrombasthenia (GT) is a rare inherited bleeding disorder caused by deficiency of platelet integrin IIb3, impairing platelet aggregation and clot formation.Patients present with mucocutaneous bleeding, while severe cases develop gastrointestinal (GI) and life-threatening hemorrhages.Management relies on platelet transfusions for acute episodes and recombinant factor VIIa for refractory or perioperative cases.Protein S (PS), a natural anticoagulant in blood, acts as a cofactor for activated protein C and tissue factor pathway inhibitor, and directly regulates prothrombinase and tenase complexes, thereby increasing thrombin generation (TG).We previously showed hepatic PS silencing with small interfering RNA (PS-siRNA) (Fig. A) rebalanced hemostasis in hemophilia models.This strategy may also therapeutically benefit GT.Here, we evaluated whether PS-siRNA improves TG and provides prophylactic protection against bleeding in GT.Methods: GT mice (Itgb3/) received a single subcutaneous dose of PS-siRNA or vehicle (Fig. B).After