Hemab Reports Durable Phase 2 Results for Sutacimig in Glanzmann Thrombasthenia, Advances Toward Phase 3

Hemab Therapeutics has reported encouraging long-term clinical and preclinical data supporting the development of sutacimig for rare inherited bleeding disorders. At the International Society on Thrombosis and Haemostasis (ISTH) 2026 Congress in Paris, the company presented updated Phase 2 long-term extension (LTE) results demonstrating durable bleed reduction and a manageable safety profile in patients with Glanzmann thrombasthenia (GT). The U.S. Food and Drug Administration (FDA) has aligned with the proposed Phase 3 dose and weekly treatment regimen, with trial initiation planned for the second half of 2026.

Sutacimig Targets the Underlying Biology of Rare Bleeding Disorders

Glanzmann thrombasthenia is a rare inherited platelet disorder characterized by recurrent, sometimes life-threatening bleeding episodes. Despite the substantial disease burden, no approved prophylactic therapy currently exists, leaving most patients dependent on intravenous treatment after bleeding occurs.

Sutacimig (formerly HMB-001) is a subcutaneously administered bispecific antibody that binds endogenous Factor VIIa and activated platelets through TLT-1, increasing thrombin generation at the site of vascular injury. The therapy has received FDA Fast Track, Breakthrough Therapy, and Orphan Drug designations for GT, along with regulatory incentives in Europe and the United Kingdom.

Phase 2 Extension Shows Sustained Bleeding Reduction

Hemab presented results from the Phase 2 long-term extension (LTE) of its ongoing sutacimig study (NCT06211634) in patients with Glanzmann thrombasthenia. The LTE enrolled 34 participants treated for a median of 6.9 months, with some receiving therapy for up to 15.9 months.

Key findings included

• Ninety-two percent of participants who experienced bleeding during the run-in period achieved reductions in annualized treated bleeding rates (ATBR).
• Among patients with prior high-intensity bleeding requiring transfusions, recombinant Factor VIIa (rFVIIa), or hospitalization, the mean annualized high-intensity treated bleed rate fell by 62%.
• Patients receiving the low-dose weekly regimen achieved an approximately 84% reduction in mean ATBR.
• Three participants successfully underwent surgical or dental procedures while receiving sutacimig, with only one requiring a single post-procedure dose of rFVIIa.

Safety findings remained generally consistent with earlier studies. Most adverse events were mild to moderate, and investigators reported no treatment-related Grade 3 or higher adverse events. Three Grade 2 thromboembolic events occurred in patients receiving higher exposure regimens or those with multiple risk factors. All events responded to standard anticoagulation and were resolved or improving at data cutoff. These findings supported selection of a 0.2 mg/kg once-weekly Phase 3 dose, endorsed by the FDA.

Preclinical Findings Support Expansion into Factor VII Deficiency

Hemab also presented preclinical data evaluating sutacimig in congenital Factor VII deficiency (FVIID). Laboratory studies demonstrated restoration of thrombin generation under disease-mimicking conditions. The antibody retained predicted binding for more than 90% of severe-to-moderate FVIID variants in mutation databases and confirmed activity across 22 of 25 tested variants, supporting broad applicability for the ongoing Phase 2 study.

Natural History Studies Highlight Unmet Need

Additional analyses from the GT360 natural history study and the ATHN Transcends registry reinforced the substantial burden of GT. More than 90% of younger patients experienced at least one bleed each week, while 72% of adults aged 40 years or older continued to report weekly bleeding. Depressive symptoms occurred at rates three to four times higher than those reported in the general population.

Registry data also showed that prophylactic therapy remains uncommon. During 16.6 patient-years of prospective follow-up, only 14% of patients received prophylaxis, while 44% of bleeding episodes went untreated.

Executive Perspective

Hemab leadership said the updated clinical findings, together with real-world natural history data, support a transition from reactive management toward preventive treatment in GT. Investigators also noted that the long-term extension demonstrated sustained prophylactic benefit while providing the first successful surgical experience with sutacimig during the study, strengthening the rationale for Phase 3 evaluation.

Path Forward

Hemab plans to begin its Phase 3 trial of sutacimig in the second half of 2026 using the FDA-endorsed once-weekly dosing regimen. The company also continues to evaluate the therapy’s potential in Factor VII deficiency while advancing additional hemostasis programs, including HMB-002 for von Willebrand disease and HMB-003 for broader bleeding indications.

Reference

Hemab Therapeutics Presents Clinical and Preclinical Data from Sutacimig in Glanzmann Thrombasthenia and Factor VII Deficiency at the ISTH 2026 Congress | Tue, 07/14/2026 – 07:45