Denmark-based Hemab Therapeutics announced that its Phase 2 study for sutacimig in Glanzmann thrombasthenia (GT) delivered strong, “clinically meaningful” reductions in treated bleeding, indicating “transformational potential” for the rare disease. Hemab will now move the drug to a pivotal Phase 3 trial. The results were presented orally at the 2025 American Society of Hematology Annual Meeting (ASH 2025).
Sutacimig is a first-in-class, subcutaneously administered bispecific antibody designed to enhance hemostatic plug formation by binding endogenous factor VIIa and recruiting it to activated platelets via TLT-1 on the platelet surface. If advanced successfully, sutacimig could shift GT care from crisis management toward ongoing prophylaxis, reducing bleeding episodes and improving quality of life.
Key findings from the CL-101 study
- In the weekly-dosing cohort of the CL-101 multiple-ascending dose study, sutacimig achieved an estimated 87% reduction in annualized treated bleeding rate (ATBR) (95% CI: 80%, 92%) across different bleed types and anatomical locations.
- The treatment completely eliminated bleeds requiring “high-intensity” interventions (such as recombinant factor VIIa, platelet transfusions, or plasma) during the study period — representing a 100% reduction in that bleed category.
- Safety and tolerability appeared acceptable: adverse events were mostly mild or moderate, and only one treatment-related serious event (grade 2 deep vein thrombosis) occurred, at the highest dose level (0.9 mg/kg).
- Five participants developed anti-drug antibodies (ADA) affecting pharmacokinetics/pharmacodynamics, but antibody titres resolved in one participant with continued dosing and were not associated with safety issues.
- Importantly, 82% of participants opted to enter the long-term extension study, underlining patient willingness to stay on prophylactic treatment.
Why this matters
GT is a rare, inherited bleeding disorder characterized by life-long risk of severe spontaneous or traumatic bleeds, and currently there are no approved prophylactic therapies, treatment is reactive, often involving platelet transfusions or recombinant factor VIIa during bleeding episodes.
Hemab itself is among the leading drug developers for the disease, and explored the use of hemophilia therapy Sevenfact (eptacog beta) for the condition in Phase 2 trials in partnership with French firm LFB BioPharmaceuticals. Novo Nordisk has also tested out its hemophilia drug Alhemo (concizumab) for GT in preclinical studies. However, sutacimig is the first candidate to show robust prophylactic efficacy in GT.Given the robust Phase 2 outcomes and favourable tolerability, Hemab plans to initiate a pivotal Phase 3 registration study in 2026.